1/*
   2 * Copyright © 2014 Red Hat
   3 *
   4 * Permission to use, copy, modify, distribute, and sell this software and its
   5 * documentation for any purpose is hereby granted without fee, provided that
   6 * the above copyright notice appear in all copies and that both that copyright
   7 * notice and this permission notice appear in supporting documentation, and
   8 * that the name of the copyright holders not be used in advertising or
   9 * publicity pertaining to distribution of the software without specific,
  10 * written prior permission.  The copyright holders make no representations
  11 * about the suitability of this software for any purpose.  It is provided "as
  12 * is" without express or implied warranty.
  13 *
  14 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  15 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  16 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  17 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  18 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  19 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  20 * OF THIS SOFTWARE.
  21 */
  22
  23#include <linux/delay.h>
  24#include <linux/errno.h>
  25#include <linux/i2c.h>
  26#include <linux/init.h>
  27#include <linux/kernel.h>
  28#include <linux/sched.h>
  29#include <linux/seq_file.h>
  30#include <linux/iopoll.h>
  31
  32#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
  33#include <linux/stacktrace.h>
  34#include <linux/sort.h>
  35#include <linux/timekeeping.h>
  36#include <linux/math64.h>
  37#endif
  38
  39#include <drm/drm_atomic.h>
  40#include <drm/drm_atomic_helper.h>
  41#include <drm/drm_dp_mst_helper.h>
  42#include <drm/drm_drv.h>
  43#include <drm/drm_print.h>
  44#include <drm/drm_probe_helper.h>
  45
  46#include "drm_crtc_helper_internal.h"
  47#include "drm_dp_mst_topology_internal.h"
  48
  49/**
  50 * DOC: dp mst helper
  51 *
  52 * These functions contain parts of the DisplayPort 1.2a MultiStream Transport
  53 * protocol. The helpers contain a topology manager and bandwidth manager.
  54 * The helpers encapsulate the sending and received of sideband msgs.
  55 */
  56struct drm_dp_pending_up_req {
  57	struct drm_dp_sideband_msg_hdr hdr;
  58	struct drm_dp_sideband_msg_req_body msg;
  59	struct list_head next;
  60};
  61
  62static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
  63				  char *buf);
  64
  65static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port);
  66
  67static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
  68				     int id,
  69				     struct drm_dp_payload *payload);
  70
  71static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
  72				 struct drm_dp_mst_port *port,
  73				 int offset, int size, u8 *bytes);
  74static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
  75				  struct drm_dp_mst_port *port,
  76				  int offset, int size, u8 *bytes);
  77
  78static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
  79				    struct drm_dp_mst_branch *mstb);
  80
  81static void
  82drm_dp_send_clear_payload_id_table(struct drm_dp_mst_topology_mgr *mgr,
  83				   struct drm_dp_mst_branch *mstb);
  84
  85static int drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
  86					   struct drm_dp_mst_branch *mstb,
  87					   struct drm_dp_mst_port *port);
  88static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
  89				 u8 *guid);
  90
  91static int drm_dp_mst_register_i2c_bus(struct drm_dp_mst_port *port);
  92static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_mst_port *port);
  93static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr);
  94
  95#define DBG_PREFIX "[dp_mst]"
  96
  97#define DP_STR(x) [DP_ ## x] = #x
  98
  99static const char *drm_dp_mst_req_type_str(u8 req_type)
 100{
 101	static const char * const req_type_str[] = {
 102		DP_STR(GET_MSG_TRANSACTION_VERSION),
 103		DP_STR(LINK_ADDRESS),
 104		DP_STR(CONNECTION_STATUS_NOTIFY),
 105		DP_STR(ENUM_PATH_RESOURCES),
 106		DP_STR(ALLOCATE_PAYLOAD),
 107		DP_STR(QUERY_PAYLOAD),
 108		DP_STR(RESOURCE_STATUS_NOTIFY),
 109		DP_STR(CLEAR_PAYLOAD_ID_TABLE),
 110		DP_STR(REMOTE_DPCD_READ),
 111		DP_STR(REMOTE_DPCD_WRITE),
 112		DP_STR(REMOTE_I2C_READ),
 113		DP_STR(REMOTE_I2C_WRITE),
 114		DP_STR(POWER_UP_PHY),
 115		DP_STR(POWER_DOWN_PHY),
 116		DP_STR(SINK_EVENT_NOTIFY),
 117		DP_STR(QUERY_STREAM_ENC_STATUS),
 118	};
 119
 120	if (req_type >= ARRAY_SIZE(req_type_str) ||
 121	    !req_type_str[req_type])
 122		return "unknown";
 123
 124	return req_type_str[req_type];
 125}
 126
 127#undef DP_STR
 128#define DP_STR(x) [DP_NAK_ ## x] = #x
 129
 130static const char *drm_dp_mst_nak_reason_str(u8 nak_reason)
 131{
 132	static const char * const nak_reason_str[] = {
 133		DP_STR(WRITE_FAILURE),
 134		DP_STR(INVALID_READ),
 135		DP_STR(CRC_FAILURE),
 136		DP_STR(BAD_PARAM),
 137		DP_STR(DEFER),
 138		DP_STR(LINK_FAILURE),
 139		DP_STR(NO_RESOURCES),
 140		DP_STR(DPCD_FAIL),
 141		DP_STR(I2C_NAK),
 142		DP_STR(ALLOCATE_FAIL),
 143	};
 144
 145	if (nak_reason >= ARRAY_SIZE(nak_reason_str) ||
 146	    !nak_reason_str[nak_reason])
 147		return "unknown";
 148
 149	return nak_reason_str[nak_reason];
 150}
 151
 152#undef DP_STR
 153#define DP_STR(x) [DRM_DP_SIDEBAND_TX_ ## x] = #x
 154
 155static const char *drm_dp_mst_sideband_tx_state_str(int state)
 156{
 157	static const char * const sideband_reason_str[] = {
 158		DP_STR(QUEUED),
 159		DP_STR(START_SEND),
 160		DP_STR(SENT),
 161		DP_STR(RX),
 162		DP_STR(TIMEOUT),
 163	};
 164
 165	if (state >= ARRAY_SIZE(sideband_reason_str) ||
 166	    !sideband_reason_str[state])
 167		return "unknown";
 168
 169	return sideband_reason_str[state];
 170}
 171
 172static int
 173drm_dp_mst_rad_to_str(const u8 rad[8], u8 lct, char *out, size_t len)
 174{
 175	int i;
 176	u8 unpacked_rad[16];
 177
 178	for (i = 0; i < lct; i++) {
 179		if (i % 2)
 180			unpacked_rad[i] = rad[i / 2] >> 4;
 181		else
 182			unpacked_rad[i] = rad[i / 2] & BIT_MASK(4);
 183	}
 184
 185	/* TODO: Eventually add something to printk so we can format the rad
 186	 * like this: 1.2.3
 187	 */
 188	return snprintf(out, len, "%*phC", lct, unpacked_rad);
 189}
 190
 191/* sideband msg handling */
 192static u8 drm_dp_msg_header_crc4(const uint8_t *data, size_t num_nibbles)
 193{
 194	u8 bitmask = 0x80;
 195	u8 bitshift = 7;
 196	u8 array_index = 0;
 197	int number_of_bits = num_nibbles * 4;
 198	u8 remainder = 0;
 199
 200	while (number_of_bits != 0) {
 201		number_of_bits--;
 202		remainder <<= 1;
 203		remainder |= (data[array_index] & bitmask) >> bitshift;
 204		bitmask >>= 1;
 205		bitshift--;
 206		if (bitmask == 0) {
 207			bitmask = 0x80;
 208			bitshift = 7;
 209			array_index++;
 210		}
 211		if ((remainder & 0x10) == 0x10)
 212			remainder ^= 0x13;
 213	}
 214
 215	number_of_bits = 4;
 216	while (number_of_bits != 0) {
 217		number_of_bits--;
 218		remainder <<= 1;
 219		if ((remainder & 0x10) != 0)
 220			remainder ^= 0x13;
 221	}
 222
 223	return remainder;
 224}
 225
 226static u8 drm_dp_msg_data_crc4(const uint8_t *data, u8 number_of_bytes)
 227{
 228	u8 bitmask = 0x80;
 229	u8 bitshift = 7;
 230	u8 array_index = 0;
 231	int number_of_bits = number_of_bytes * 8;
 232	u16 remainder = 0;
 233
 234	while (number_of_bits != 0) {
 235		number_of_bits--;
 236		remainder <<= 1;
 237		remainder |= (data[array_index] & bitmask) >> bitshift;
 238		bitmask >>= 1;
 239		bitshift--;
 240		if (bitmask == 0) {
 241			bitmask = 0x80;
 242			bitshift = 7;
 243			array_index++;
 244		}
 245		if ((remainder & 0x100) == 0x100)
 246			remainder ^= 0xd5;
 247	}
 248
 249	number_of_bits = 8;
 250	while (number_of_bits != 0) {
 251		number_of_bits--;
 252		remainder <<= 1;
 253		if ((remainder & 0x100) != 0)
 254			remainder ^= 0xd5;
 255	}
 256
 257	return remainder & 0xff;
 258}
 259static inline u8 drm_dp_calc_sb_hdr_size(struct drm_dp_sideband_msg_hdr *hdr)
 260{
 261	u8 size = 3;
 262
 263	size += (hdr->lct / 2);
 264	return size;
 265}
 266
 267static void drm_dp_encode_sideband_msg_hdr(struct drm_dp_sideband_msg_hdr *hdr,
 268					   u8 *buf, int *len)
 269{
 270	int idx = 0;
 271	int i;
 272	u8 crc4;
 273
 274	buf[idx++] = ((hdr->lct & 0xf) << 4) | (hdr->lcr & 0xf);
 275	for (i = 0; i < (hdr->lct / 2); i++)
 276		buf[idx++] = hdr->rad[i];
 277	buf[idx++] = (hdr->broadcast << 7) | (hdr->path_msg << 6) |
 278		(hdr->msg_len & 0x3f);
 279	buf[idx++] = (hdr->somt << 7) | (hdr->eomt << 6) | (hdr->seqno << 4);
 280
 281	crc4 = drm_dp_msg_header_crc4(buf, (idx * 2) - 1);
 282	buf[idx - 1] |= (crc4 & 0xf);
 283
 284	*len = idx;
 285}
 286
 287static bool drm_dp_decode_sideband_msg_hdr(struct drm_dp_sideband_msg_hdr *hdr,
 288					   u8 *buf, int buflen, u8 *hdrlen)
 289{
 290	u8 crc4;
 291	u8 len;
 292	int i;
 293	u8 idx;
 294
 295	if (buf[0] == 0)
 296		return false;
 297	len = 3;
 298	len += ((buf[0] & 0xf0) >> 4) / 2;
 299	if (len > buflen)
 300		return false;
 301	crc4 = drm_dp_msg_header_crc4(buf, (len * 2) - 1);
 302
 303	if ((crc4 & 0xf) != (buf[len - 1] & 0xf)) {
 304		DRM_DEBUG_KMS("crc4 mismatch 0x%x 0x%x\n", crc4, buf[len - 1]);
 305		return false;
 306	}
 307
 308	hdr->lct = (buf[0] & 0xf0) >> 4;
 309	hdr->lcr = (buf[0] & 0xf);
 310	idx = 1;
 311	for (i = 0; i < (hdr->lct / 2); i++)
 312		hdr->rad[i] = buf[idx++];
 313	hdr->broadcast = (buf[idx] >> 7) & 0x1;
 314	hdr->path_msg = (buf[idx] >> 6) & 0x1;
 315	hdr->msg_len = buf[idx] & 0x3f;
 316	idx++;
 317	hdr->somt = (buf[idx] >> 7) & 0x1;
 318	hdr->eomt = (buf[idx] >> 6) & 0x1;
 319	hdr->seqno = (buf[idx] >> 4) & 0x1;
 320	idx++;
 321	*hdrlen = idx;
 322	return true;
 323}
 324
 325void
 326drm_dp_encode_sideband_req(const struct drm_dp_sideband_msg_req_body *req,
 327			   struct drm_dp_sideband_msg_tx *raw)
 328{
 329	int idx = 0;
 330	int i;
 331	u8 *buf = raw->msg;
 332
 333	buf[idx++] = req->req_type & 0x7f;
 334
 335	switch (req->req_type) {
 336	case DP_ENUM_PATH_RESOURCES:
 337	case DP_POWER_DOWN_PHY:
 338	case DP_POWER_UP_PHY:
 339		buf[idx] = (req->u.port_num.port_number & 0xf) << 4;
 340		idx++;
 341		break;
 342	case DP_ALLOCATE_PAYLOAD:
 343		buf[idx] = (req->u.allocate_payload.port_number & 0xf) << 4 |
 344			(req->u.allocate_payload.number_sdp_streams & 0xf);
 345		idx++;
 346		buf[idx] = (req->u.allocate_payload.vcpi & 0x7f);
 347		idx++;
 348		buf[idx] = (req->u.allocate_payload.pbn >> 8);
 349		idx++;
 350		buf[idx] = (req->u.allocate_payload.pbn & 0xff);
 351		idx++;
 352		for (i = 0; i < req->u.allocate_payload.number_sdp_streams / 2; i++) {
 353			buf[idx] = ((req->u.allocate_payload.sdp_stream_sink[i * 2] & 0xf) << 4) |
 354				(req->u.allocate_payload.sdp_stream_sink[i * 2 + 1] & 0xf);
 355			idx++;
 356		}
 357		if (req->u.allocate_payload.number_sdp_streams & 1) {
 358			i = req->u.allocate_payload.number_sdp_streams - 1;
 359			buf[idx] = (req->u.allocate_payload.sdp_stream_sink[i] & 0xf) << 4;
 360			idx++;
 361		}
 362		break;
 363	case DP_QUERY_PAYLOAD:
 364		buf[idx] = (req->u.query_payload.port_number & 0xf) << 4;
 365		idx++;
 366		buf[idx] = (req->u.query_payload.vcpi & 0x7f);
 367		idx++;
 368		break;
 369	case DP_REMOTE_DPCD_READ:
 370		buf[idx] = (req->u.dpcd_read.port_number & 0xf) << 4;
 371		buf[idx] |= ((req->u.dpcd_read.dpcd_address & 0xf0000) >> 16) & 0xf;
 372		idx++;
 373		buf[idx] = (req->u.dpcd_read.dpcd_address & 0xff00) >> 8;
 374		idx++;
 375		buf[idx] = (req->u.dpcd_read.dpcd_address & 0xff);
 376		idx++;
 377		buf[idx] = (req->u.dpcd_read.num_bytes);
 378		idx++;
 379		break;
 380
 381	case DP_REMOTE_DPCD_WRITE:
 382		buf[idx] = (req->u.dpcd_write.port_number & 0xf) << 4;
 383		buf[idx] |= ((req->u.dpcd_write.dpcd_address & 0xf0000) >> 16) & 0xf;
 384		idx++;
 385		buf[idx] = (req->u.dpcd_write.dpcd_address & 0xff00) >> 8;
 386		idx++;
 387		buf[idx] = (req->u.dpcd_write.dpcd_address & 0xff);
 388		idx++;
 389		buf[idx] = (req->u.dpcd_write.num_bytes);
 390		idx++;
 391		memcpy(&buf[idx], req->u.dpcd_write.bytes, req->u.dpcd_write.num_bytes);
 392		idx += req->u.dpcd_write.num_bytes;
 393		break;
 394	case DP_REMOTE_I2C_READ:
 395		buf[idx] = (req->u.i2c_read.port_number & 0xf) << 4;
 396		buf[idx] |= (req->u.i2c_read.num_transactions & 0x3);
 397		idx++;
 398		for (i = 0; i < (req->u.i2c_read.num_transactions & 0x3); i++) {
 399			buf[idx] = req->u.i2c_read.transactions[i].i2c_dev_id & 0x7f;
 400			idx++;
 401			buf[idx] = req->u.i2c_read.transactions[i].num_bytes;
 402			idx++;
 403			memcpy(&buf[idx], req->u.i2c_read.transactions[i].bytes, req->u.i2c_read.transactions[i].num_bytes);
 404			idx += req->u.i2c_read.transactions[i].num_bytes;
 405
 406			buf[idx] = (req->u.i2c_read.transactions[i].no_stop_bit & 0x1) << 4;
 407			buf[idx] |= (req->u.i2c_read.transactions[i].i2c_transaction_delay & 0xf);
 408			idx++;
 409		}
 410		buf[idx] = (req->u.i2c_read.read_i2c_device_id) & 0x7f;
 411		idx++;
 412		buf[idx] = (req->u.i2c_read.num_bytes_read);
 413		idx++;
 414		break;
 415
 416	case DP_REMOTE_I2C_WRITE:
 417		buf[idx] = (req->u.i2c_write.port_number & 0xf) << 4;
 418		idx++;
 419		buf[idx] = (req->u.i2c_write.write_i2c_device_id) & 0x7f;
 420		idx++;
 421		buf[idx] = (req->u.i2c_write.num_bytes);
 422		idx++;
 423		memcpy(&buf[idx], req->u.i2c_write.bytes, req->u.i2c_write.num_bytes);
 424		idx += req->u.i2c_write.num_bytes;
 425		break;
 426	}
 427	raw->cur_len = idx;
 428}
 429EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_encode_sideband_req);
 430
 431/* Decode a sideband request we've encoded, mainly used for debugging */
 432int
 433drm_dp_decode_sideband_req(const struct drm_dp_sideband_msg_tx *raw,
 434			   struct drm_dp_sideband_msg_req_body *req)
 435{
 436	const u8 *buf = raw->msg;
 437	int i, idx = 0;
 438
 439	req->req_type = buf[idx++] & 0x7f;
 440	switch (req->req_type) {
 441	case DP_ENUM_PATH_RESOURCES:
 442	case DP_POWER_DOWN_PHY:
 443	case DP_POWER_UP_PHY:
 444		req->u.port_num.port_number = (buf[idx] >> 4) & 0xf;
 445		break;
 446	case DP_ALLOCATE_PAYLOAD:
 447		{
 448			struct drm_dp_allocate_payload *a =
 449				&req->u.allocate_payload;
 450
 451			a->number_sdp_streams = buf[idx] & 0xf;
 452			a->port_number = (buf[idx] >> 4) & 0xf;
 453
 454			WARN_ON(buf[++idx] & 0x80);
 455			a->vcpi = buf[idx] & 0x7f;
 456
 457			a->pbn = buf[++idx] << 8;
 458			a->pbn |= buf[++idx];
 459
 460			idx++;
 461			for (i = 0; i < a->number_sdp_streams; i++) {
 462				a->sdp_stream_sink[i] =
 463					(buf[idx + (i / 2)] >> ((i % 2) ? 0 : 4)) & 0xf;
 464			}
 465		}
 466		break;
 467	case DP_QUERY_PAYLOAD:
 468		req->u.query_payload.port_number = (buf[idx] >> 4) & 0xf;
 469		WARN_ON(buf[++idx] & 0x80);
 470		req->u.query_payload.vcpi = buf[idx] & 0x7f;
 471		break;
 472	case DP_REMOTE_DPCD_READ:
 473		{
 474			struct drm_dp_remote_dpcd_read *r = &req->u.dpcd_read;
 475
 476			r->port_number = (buf[idx] >> 4) & 0xf;
 477
 478			r->dpcd_address = (buf[idx] << 16) & 0xf0000;
 479			r->dpcd_address |= (buf[++idx] << 8) & 0xff00;
 480			r->dpcd_address |= buf[++idx] & 0xff;
 481
 482			r->num_bytes = buf[++idx];
 483		}
 484		break;
 485	case DP_REMOTE_DPCD_WRITE:
 486		{
 487			struct drm_dp_remote_dpcd_write *w =
 488				&req->u.dpcd_write;
 489
 490			w->port_number = (buf[idx] >> 4) & 0xf;
 491
 492			w->dpcd_address = (buf[idx] << 16) & 0xf0000;
 493			w->dpcd_address |= (buf[++idx] << 8) & 0xff00;
 494			w->dpcd_address |= buf[++idx] & 0xff;
 495
 496			w->num_bytes = buf[++idx];
 497
 498			w->bytes = kmemdup(&buf[++idx], w->num_bytes,
 499					   GFP_KERNEL);
 500			if (!w->bytes)
 501				return -ENOMEM;
 502		}
 503		break;
 504	case DP_REMOTE_I2C_READ:
 505		{
 506			struct drm_dp_remote_i2c_read *r = &req->u.i2c_read;
 507			struct drm_dp_remote_i2c_read_tx *tx;
 508			bool failed = false;
 509
 510			r->num_transactions = buf[idx] & 0x3;
 511			r->port_number = (buf[idx] >> 4) & 0xf;
 512			for (i = 0; i < r->num_transactions; i++) {
 513				tx = &r->transactions[i];
 514
 515				tx->i2c_dev_id = buf[++idx] & 0x7f;
 516				tx->num_bytes = buf[++idx];
 517				tx->bytes = kmemdup(&buf[++idx],
 518						    tx->num_bytes,
 519						    GFP_KERNEL);
 520				if (!tx->bytes) {
 521					failed = true;
 522					break;
 523				}
 524				idx += tx->num_bytes;
 525				tx->no_stop_bit = (buf[idx] >> 5) & 0x1;
 526				tx->i2c_transaction_delay = buf[idx] & 0xf;
 527			}
 528
 529			if (failed) {
 530				for (i = 0; i < r->num_transactions; i++) {
 531					tx = &r->transactions[i];
 532					kfree(tx->bytes);
 533				}
 534				return -ENOMEM;
 535			}
 536
 537			r->read_i2c_device_id = buf[++idx] & 0x7f;
 538			r->num_bytes_read = buf[++idx];
 539		}
 540		break;
 541	case DP_REMOTE_I2C_WRITE:
 542		{
 543			struct drm_dp_remote_i2c_write *w = &req->u.i2c_write;
 544
 545			w->port_number = (buf[idx] >> 4) & 0xf;
 546			w->write_i2c_device_id = buf[++idx] & 0x7f;
 547			w->num_bytes = buf[++idx];
 548			w->bytes = kmemdup(&buf[++idx], w->num_bytes,
 549					   GFP_KERNEL);
 550			if (!w->bytes)
 551				return -ENOMEM;
 552		}
 553		break;
 554	}
 555
 556	return 0;
 557}
 558EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_decode_sideband_req);
 559
 560void
 561drm_dp_dump_sideband_msg_req_body(const struct drm_dp_sideband_msg_req_body *req,
 562				  int indent, struct drm_printer *printer)
 563{
 564	int i;
 565
 566#define P(f, ...) drm_printf_indent(printer, indent, f, ##__VA_ARGS__)
 567	if (req->req_type == DP_LINK_ADDRESS) {
 568		/* No contents to print */
 569		P("type=%s\n", drm_dp_mst_req_type_str(req->req_type));
 570		return;
 571	}
 572
 573	P("type=%s contents:\n", drm_dp_mst_req_type_str(req->req_type));
 574	indent++;
 575
 576	switch (req->req_type) {
 577	case DP_ENUM_PATH_RESOURCES:
 578	case DP_POWER_DOWN_PHY:
 579	case DP_POWER_UP_PHY:
 580		P("port=%d\n", req->u.port_num.port_number);
 581		break;
 582	case DP_ALLOCATE_PAYLOAD:
 583		P("port=%d vcpi=%d pbn=%d sdp_streams=%d %*ph\n",
 584		  req->u.allocate_payload.port_number,
 585		  req->u.allocate_payload.vcpi, req->u.allocate_payload.pbn,
 586		  req->u.allocate_payload.number_sdp_streams,
 587		  req->u.allocate_payload.number_sdp_streams,
 588		  req->u.allocate_payload.sdp_stream_sink);
 589		break;
 590	case DP_QUERY_PAYLOAD:
 591		P("port=%d vcpi=%d\n",
 592		  req->u.query_payload.port_number,
 593		  req->u.query_payload.vcpi);
 594		break;
 595	case DP_REMOTE_DPCD_READ:
 596		P("port=%d dpcd_addr=%05x len=%d\n",
 597		  req->u.dpcd_read.port_number, req->u.dpcd_read.dpcd_address,
 598		  req->u.dpcd_read.num_bytes);
 599		break;
 600	case DP_REMOTE_DPCD_WRITE:
 601		P("port=%d addr=%05x len=%d: %*ph\n",
 602		  req->u.dpcd_write.port_number,
 603		  req->u.dpcd_write.dpcd_address,
 604		  req->u.dpcd_write.num_bytes, req->u.dpcd_write.num_bytes,
 605		  req->u.dpcd_write.bytes);
 606		break;
 607	case DP_REMOTE_I2C_READ:
 608		P("port=%d num_tx=%d id=%d size=%d:\n",
 609		  req->u.i2c_read.port_number,
 610		  req->u.i2c_read.num_transactions,
 611		  req->u.i2c_read.read_i2c_device_id,
 612		  req->u.i2c_read.num_bytes_read);
 613
 614		indent++;
 615		for (i = 0; i < req->u.i2c_read.num_transactions; i++) {
 616			const struct drm_dp_remote_i2c_read_tx *rtx =
 617				&req->u.i2c_read.transactions[i];
 618
 619			P("%d: id=%03d size=%03d no_stop_bit=%d tx_delay=%03d: %*ph\n",
 620			  i, rtx->i2c_dev_id, rtx->num_bytes,
 621			  rtx->no_stop_bit, rtx->i2c_transaction_delay,
 622			  rtx->num_bytes, rtx->bytes);
 623		}
 624		break;
 625	case DP_REMOTE_I2C_WRITE:
 626		P("port=%d id=%d size=%d: %*ph\n",
 627		  req->u.i2c_write.port_number,
 628		  req->u.i2c_write.write_i2c_device_id,
 629		  req->u.i2c_write.num_bytes, req->u.i2c_write.num_bytes,
 630		  req->u.i2c_write.bytes);
 631		break;
 632	default:
 633		P("???\n");
 634		break;
 635	}
 636#undef P
 637}
 638EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_dump_sideband_msg_req_body);
 639
 640static inline void
 641drm_dp_mst_dump_sideband_msg_tx(struct drm_printer *p,
 642				const struct drm_dp_sideband_msg_tx *txmsg)
 643{
 644	struct drm_dp_sideband_msg_req_body req;
 645	char buf[64];
 646	int ret;
 647	int i;
 648
 649	drm_dp_mst_rad_to_str(txmsg->dst->rad, txmsg->dst->lct, buf,
 650			      sizeof(buf));
 651	drm_printf(p, "txmsg cur_offset=%x cur_len=%x seqno=%x state=%s path_msg=%d dst=%s\n",
 652		   txmsg->cur_offset, txmsg->cur_len, txmsg->seqno,
 653		   drm_dp_mst_sideband_tx_state_str(txmsg->state),
 654		   txmsg->path_msg, buf);
 655
 656	ret = drm_dp_decode_sideband_req(txmsg, &req);
 657	if (ret) {
 658		drm_printf(p, "<failed to decode sideband req: %d>\n", ret);
 659		return;
 660	}
 661	drm_dp_dump_sideband_msg_req_body(&req, 1, p);
 662
 663	switch (req.req_type) {
 664	case DP_REMOTE_DPCD_WRITE:
 665		kfree(req.u.dpcd_write.bytes);
 666		break;
 667	case DP_REMOTE_I2C_READ:
 668		for (i = 0; i < req.u.i2c_read.num_transactions; i++)
 669			kfree(req.u.i2c_read.transactions[i].bytes);
 670		break;
 671	case DP_REMOTE_I2C_WRITE:
 672		kfree(req.u.i2c_write.bytes);
 673		break;
 674	}
 675}
 676
 677static void drm_dp_crc_sideband_chunk_req(u8 *msg, u8 len)
 678{
 679	u8 crc4;
 680
 681	crc4 = drm_dp_msg_data_crc4(msg, len);
 682	msg[len] = crc4;
 683}
 684
 685static void drm_dp_encode_sideband_reply(struct drm_dp_sideband_msg_reply_body *rep,
 686					 struct drm_dp_sideband_msg_tx *raw)
 687{
 688	int idx = 0;
 689	u8 *buf = raw->msg;
 690
 691	buf[idx++] = (rep->reply_type & 0x1) << 7 | (rep->req_type & 0x7f);
 692
 693	raw->cur_len = idx;
 694}
 695
 696static int drm_dp_sideband_msg_set_header(struct drm_dp_sideband_msg_rx *msg,
 697					  struct drm_dp_sideband_msg_hdr *hdr,
 698					  u8 hdrlen)
 699{
 700	/*
 701	 * ignore out-of-order messages or messages that are part of a
 702	 * failed transaction
 703	 */
 704	if (!hdr->somt && !msg->have_somt)
 705		return false;
 706
 707	/* get length contained in this portion */
 708	msg->curchunk_idx = 0;
 709	msg->curchunk_len = hdr->msg_len;
 710	msg->curchunk_hdrlen = hdrlen;
 711
 712	/* we have already gotten an somt - don't bother parsing */
 713	if (hdr->somt && msg->have_somt)
 714		return false;
 715
 716	if (hdr->somt) {
 717		memcpy(&msg->initial_hdr, hdr,
 718		       sizeof(struct drm_dp_sideband_msg_hdr));
 719		msg->have_somt = true;
 720	}
 721	if (hdr->eomt)
 722		msg->have_eomt = true;
 723
 724	return true;
 725}
 726
 727/* this adds a chunk of msg to the builder to get the final msg */
 728static bool drm_dp_sideband_append_payload(struct drm_dp_sideband_msg_rx *msg,
 729					   u8 *replybuf, u8 replybuflen)
 730{
 731	u8 crc4;
 732
 733	memcpy(&msg->chunk[msg->curchunk_idx], replybuf, replybuflen);
 734	msg->curchunk_idx += replybuflen;
 735
 736	if (msg->curchunk_idx >= msg->curchunk_len) {
 737		/* do CRC */
 738		crc4 = drm_dp_msg_data_crc4(msg->chunk, msg->curchunk_len - 1);
 739		if (crc4 != msg->chunk[msg->curchunk_len - 1])
 740			print_hex_dump(KERN_DEBUG, "wrong crc",
 741				       DUMP_PREFIX_NONE, 16, 1,
 742				       msg->chunk,  msg->curchunk_len, false);
 743		/* copy chunk into bigger msg */
 744		memcpy(&msg->msg[msg->curlen], msg->chunk, msg->curchunk_len - 1);
 745		msg->curlen += msg->curchunk_len - 1;
 746	}
 747	return true;
 748}
 749
 750static bool drm_dp_sideband_parse_link_address(struct drm_dp_sideband_msg_rx *raw,
 751					       struct drm_dp_sideband_msg_reply_body *repmsg)
 752{
 753	int idx = 1;
 754	int i;
 755
 756	memcpy(repmsg->u.link_addr.guid, &raw->msg[idx], 16);
 757	idx += 16;
 758	repmsg->u.link_addr.nports = raw->msg[idx] & 0xf;
 759	idx++;
 760	if (idx > raw->curlen)
 761		goto fail_len;
 762	for (i = 0; i < repmsg->u.link_addr.nports; i++) {
 763		if (raw->msg[idx] & 0x80)
 764			repmsg->u.link_addr.ports[i].input_port = 1;
 765
 766		repmsg->u.link_addr.ports[i].peer_device_type = (raw->msg[idx] >> 4) & 0x7;
 767		repmsg->u.link_addr.ports[i].port_number = (raw->msg[idx] & 0xf);
 768
 769		idx++;
 770		if (idx > raw->curlen)
 771			goto fail_len;
 772		repmsg->u.link_addr.ports[i].mcs = (raw->msg[idx] >> 7) & 0x1;
 773		repmsg->u.link_addr.ports[i].ddps = (raw->msg[idx] >> 6) & 0x1;
 774		if (repmsg->u.link_addr.ports[i].input_port == 0)
 775			repmsg->u.link_addr.ports[i].legacy_device_plug_status = (raw->msg[idx] >> 5) & 0x1;
 776		idx++;
 777		if (idx > raw->curlen)
 778			goto fail_len;
 779		if (repmsg->u.link_addr.ports[i].input_port == 0) {
 780			repmsg->u.link_addr.ports[i].dpcd_revision = (raw->msg[idx]);
 781			idx++;
 782			if (idx > raw->curlen)
 783				goto fail_len;
 784			memcpy(repmsg->u.link_addr.ports[i].peer_guid, &raw->msg[idx], 16);
 785			idx += 16;
 786			if (idx > raw->curlen)
 787				goto fail_len;
 788			repmsg->u.link_addr.ports[i].num_sdp_streams = (raw->msg[idx] >> 4) & 0xf;
 789			repmsg->u.link_addr.ports[i].num_sdp_stream_sinks = (raw->msg[idx] & 0xf);
 790			idx++;
 791
 792		}
 793		if (idx > raw->curlen)
 794			goto fail_len;
 795	}
 796
 797	return true;
 798fail_len:
 799	DRM_DEBUG_KMS("link address reply parse length fail %d %d\n", idx, raw->curlen);
 800	return false;
 801}
 802
 803static bool drm_dp_sideband_parse_remote_dpcd_read(struct drm_dp_sideband_msg_rx *raw,
 804						   struct drm_dp_sideband_msg_reply_body *repmsg)
 805{
 806	int idx = 1;
 807
 808	repmsg->u.remote_dpcd_read_ack.port_number = raw->msg[idx] & 0xf;
 809	idx++;
 810	if (idx > raw->curlen)
 811		goto fail_len;
 812	repmsg->u.remote_dpcd_read_ack.num_bytes = raw->msg[idx];
 813	idx++;
 814	if (idx > raw->curlen)
 815		goto fail_len;
 816
 817	memcpy(repmsg->u.remote_dpcd_read_ack.bytes, &raw->msg[idx], repmsg->u.remote_dpcd_read_ack.num_bytes);
 818	return true;
 819fail_len:
 820	DRM_DEBUG_KMS("link address reply parse length fail %d %d\n", idx, raw->curlen);
 821	return false;
 822}
 823
 824static bool drm_dp_sideband_parse_remote_dpcd_write(struct drm_dp_sideband_msg_rx *raw,
 825						      struct drm_dp_sideband_msg_reply_body *repmsg)
 826{
 827	int idx = 1;
 828
 829	repmsg->u.remote_dpcd_write_ack.port_number = raw->msg[idx] & 0xf;
 830	idx++;
 831	if (idx > raw->curlen)
 832		goto fail_len;
 833	return true;
 834fail_len:
 835	DRM_DEBUG_KMS("parse length fail %d %d\n", idx, raw->curlen);
 836	return false;
 837}
 838
 839static bool drm_dp_sideband_parse_remote_i2c_read_ack(struct drm_dp_sideband_msg_rx *raw,
 840						      struct drm_dp_sideband_msg_reply_body *repmsg)
 841{
 842	int idx = 1;
 843
 844	repmsg->u.remote_i2c_read_ack.port_number = (raw->msg[idx] & 0xf);
 845	idx++;
 846	if (idx > raw->curlen)
 847		goto fail_len;
 848	repmsg->u.remote_i2c_read_ack.num_bytes = raw->msg[idx];
 849	idx++;
 850	/* TODO check */
 851	memcpy(repmsg->u.remote_i2c_read_ack.bytes, &raw->msg[idx], repmsg->u.remote_i2c_read_ack.num_bytes);
 852	return true;
 853fail_len:
 854	DRM_DEBUG_KMS("remote i2c reply parse length fail %d %d\n", idx, raw->curlen);
 855	return false;
 856}
 857
 858static bool drm_dp_sideband_parse_enum_path_resources_ack(struct drm_dp_sideband_msg_rx *raw,
 859							  struct drm_dp_sideband_msg_reply_body *repmsg)
 860{
 861	int idx = 1;
 862
 863	repmsg->u.path_resources.port_number = (raw->msg[idx] >> 4) & 0xf;
 864	repmsg->u.path_resources.fec_capable = raw->msg[idx] & 0x1;
 865	idx++;
 866	if (idx > raw->curlen)
 867		goto fail_len;
 868	repmsg->u.path_resources.full_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
 869	idx += 2;
 870	if (idx > raw->curlen)
 871		goto fail_len;
 872	repmsg->u.path_resources.avail_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
 873	idx += 2;
 874	if (idx > raw->curlen)
 875		goto fail_len;
 876	return true;
 877fail_len:
 878	DRM_DEBUG_KMS("enum resource parse length fail %d %d\n", idx, raw->curlen);
 879	return false;
 880}
 881
 882static bool drm_dp_sideband_parse_allocate_payload_ack(struct drm_dp_sideband_msg_rx *raw,
 883							  struct drm_dp_sideband_msg_reply_body *repmsg)
 884{
 885	int idx = 1;
 886
 887	repmsg->u.allocate_payload.port_number = (raw->msg[idx] >> 4) & 0xf;
 888	idx++;
 889	if (idx > raw->curlen)
 890		goto fail_len;
 891	repmsg->u.allocate_payload.vcpi = raw->msg[idx];
 892	idx++;
 893	if (idx > raw->curlen)
 894		goto fail_len;
 895	repmsg->u.allocate_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
 896	idx += 2;
 897	if (idx > raw->curlen)
 898		goto fail_len;
 899	return true;
 900fail_len:
 901	DRM_DEBUG_KMS("allocate payload parse length fail %d %d\n", idx, raw->curlen);
 902	return false;
 903}
 904
 905static bool drm_dp_sideband_parse_query_payload_ack(struct drm_dp_sideband_msg_rx *raw,
 906						    struct drm_dp_sideband_msg_reply_body *repmsg)
 907{
 908	int idx = 1;
 909
 910	repmsg->u.query_payload.port_number = (raw->msg[idx] >> 4) & 0xf;
 911	idx++;
 912	if (idx > raw->curlen)
 913		goto fail_len;
 914	repmsg->u.query_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
 915	idx += 2;
 916	if (idx > raw->curlen)
 917		goto fail_len;
 918	return true;
 919fail_len:
 920	DRM_DEBUG_KMS("query payload parse length fail %d %d\n", idx, raw->curlen);
 921	return false;
 922}
 923
 924static bool drm_dp_sideband_parse_power_updown_phy_ack(struct drm_dp_sideband_msg_rx *raw,
 925						       struct drm_dp_sideband_msg_reply_body *repmsg)
 926{
 927	int idx = 1;
 928
 929	repmsg->u.port_number.port_number = (raw->msg[idx] >> 4) & 0xf;
 930	idx++;
 931	if (idx > raw->curlen) {
 932		DRM_DEBUG_KMS("power up/down phy parse length fail %d %d\n",
 933			      idx, raw->curlen);
 934		return false;
 935	}
 936	return true;
 937}
 938
 939static bool drm_dp_sideband_parse_reply(struct drm_dp_sideband_msg_rx *raw,
 940					struct drm_dp_sideband_msg_reply_body *msg)
 941{
 942	memset(msg, 0, sizeof(*msg));
 943	msg->reply_type = (raw->msg[0] & 0x80) >> 7;
 944	msg->req_type = (raw->msg[0] & 0x7f);
 945
 946	if (msg->reply_type == DP_SIDEBAND_REPLY_NAK) {
 947		memcpy(msg->u.nak.guid, &raw->msg[1], 16);
 948		msg->u.nak.reason = raw->msg[17];
 949		msg->u.nak.nak_data = raw->msg[18];
 950		return false;
 951	}
 952
 953	switch (msg->req_type) {
 954	case DP_LINK_ADDRESS:
 955		return drm_dp_sideband_parse_link_address(raw, msg);
 956	case DP_QUERY_PAYLOAD:
 957		return drm_dp_sideband_parse_query_payload_ack(raw, msg);
 958	case DP_REMOTE_DPCD_READ:
 959		return drm_dp_sideband_parse_remote_dpcd_read(raw, msg);
 960	case DP_REMOTE_DPCD_WRITE:
 961		return drm_dp_sideband_parse_remote_dpcd_write(raw, msg);
 962	case DP_REMOTE_I2C_READ:
 963		return drm_dp_sideband_parse_remote_i2c_read_ack(raw, msg);
 964	case DP_ENUM_PATH_RESOURCES:
 965		return drm_dp_sideband_parse_enum_path_resources_ack(raw, msg);
 966	case DP_ALLOCATE_PAYLOAD:
 967		return drm_dp_sideband_parse_allocate_payload_ack(raw, msg);
 968	case DP_POWER_DOWN_PHY:
 969	case DP_POWER_UP_PHY:
 970		return drm_dp_sideband_parse_power_updown_phy_ack(raw, msg);
 971	case DP_CLEAR_PAYLOAD_ID_TABLE:
 972		return true; /* since there's nothing to parse */
 973	default:
 974		DRM_ERROR("Got unknown reply 0x%02x (%s)\n", msg->req_type,
 975			  drm_dp_mst_req_type_str(msg->req_type));
 976		return false;
 977	}
 978}
 979
 980static bool drm_dp_sideband_parse_connection_status_notify(struct drm_dp_sideband_msg_rx *raw,
 981							   struct drm_dp_sideband_msg_req_body *msg)
 982{
 983	int idx = 1;
 984
 985	msg->u.conn_stat.port_number = (raw->msg[idx] & 0xf0) >> 4;
 986	idx++;
 987	if (idx > raw->curlen)
 988		goto fail_len;
 989
 990	memcpy(msg->u.conn_stat.guid, &raw->msg[idx], 16);
 991	idx += 16;
 992	if (idx > raw->curlen)
 993		goto fail_len;
 994
 995	msg->u.conn_stat.legacy_device_plug_status = (raw->msg[idx] >> 6) & 0x1;
 996	msg->u.conn_stat.displayport_device_plug_status = (raw->msg[idx] >> 5) & 0x1;
 997	msg->u.conn_stat.message_capability_status = (raw->msg[idx] >> 4) & 0x1;
 998	msg->u.conn_stat.input_port = (raw->msg[idx] >> 3) & 0x1;
 999	msg->u.conn_stat.peer_device_type = (raw->msg[idx] & 0x7);
1000	idx++;
1001	return true;
1002fail_len:
1003	DRM_DEBUG_KMS("connection status reply parse length fail %d %d\n", idx, raw->curlen);
1004	return false;
1005}
1006
1007static bool drm_dp_sideband_parse_resource_status_notify(struct drm_dp_sideband_msg_rx *raw,
1008							   struct drm_dp_sideband_msg_req_body *msg)
1009{
1010	int idx = 1;
1011
1012	msg->u.resource_stat.port_number = (raw->msg[idx] & 0xf0) >> 4;
1013	idx++;
1014	if (idx > raw->curlen)
1015		goto fail_len;
1016
1017	memcpy(msg->u.resource_stat.guid, &raw->msg[idx], 16);
1018	idx += 16;
1019	if (idx > raw->curlen)
1020		goto fail_len;
1021
1022	msg->u.resource_stat.available_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
1023	idx++;
1024	return true;
1025fail_len:
1026	DRM_DEBUG_KMS("resource status reply parse length fail %d %d\n", idx, raw->curlen);
1027	return false;
1028}
1029
1030static bool drm_dp_sideband_parse_req(struct drm_dp_sideband_msg_rx *raw,
1031				      struct drm_dp_sideband_msg_req_body *msg)
1032{
1033	memset(msg, 0, sizeof(*msg));
1034	msg->req_type = (raw->msg[0] & 0x7f);
1035
1036	switch (msg->req_type) {
1037	case DP_CONNECTION_STATUS_NOTIFY:
1038		return drm_dp_sideband_parse_connection_status_notify(raw, msg);
1039	case DP_RESOURCE_STATUS_NOTIFY:
1040		return drm_dp_sideband_parse_resource_status_notify(raw, msg);
1041	default:
1042		DRM_ERROR("Got unknown request 0x%02x (%s)\n", msg->req_type,
1043			  drm_dp_mst_req_type_str(msg->req_type));
1044		return false;
1045	}
1046}
1047
1048static void build_dpcd_write(struct drm_dp_sideband_msg_tx *msg,
1049			     u8 port_num, u32 offset, u8 num_bytes, u8 *bytes)
1050{
1051	struct drm_dp_sideband_msg_req_body req;
1052
1053	req.req_type = DP_REMOTE_DPCD_WRITE;
1054	req.u.dpcd_write.port_number = port_num;
1055	req.u.dpcd_write.dpcd_address = offset;
1056	req.u.dpcd_write.num_bytes = num_bytes;
1057	req.u.dpcd_write.bytes = bytes;
1058	drm_dp_encode_sideband_req(&req, msg);
1059}
1060
1061static void build_link_address(struct drm_dp_sideband_msg_tx *msg)
1062{
1063	struct drm_dp_sideband_msg_req_body req;
1064
1065	req.req_type = DP_LINK_ADDRESS;
1066	drm_dp_encode_sideband_req(&req, msg);
1067}
1068
1069static void build_clear_payload_id_table(struct drm_dp_sideband_msg_tx *msg)
1070{
1071	struct drm_dp_sideband_msg_req_body req;
1072
1073	req.req_type = DP_CLEAR_PAYLOAD_ID_TABLE;
1074	drm_dp_encode_sideband_req(&req, msg);
1075}
1076
1077static int build_enum_path_resources(struct drm_dp_sideband_msg_tx *msg,
1078				     int port_num)
1079{
1080	struct drm_dp_sideband_msg_req_body req;
1081
1082	req.req_type = DP_ENUM_PATH_RESOURCES;
1083	req.u.port_num.port_number = port_num;
1084	drm_dp_encode_sideband_req(&req, msg);
1085	msg->path_msg = true;
1086	return 0;
1087}
1088
1089static void build_allocate_payload(struct drm_dp_sideband_msg_tx *msg,
1090				   int port_num,
1091				   u8 vcpi, uint16_t pbn,
1092				   u8 number_sdp_streams,
1093				   u8 *sdp_stream_sink)
1094{
1095	struct drm_dp_sideband_msg_req_body req;
1096
1097	memset(&req, 0, sizeof(req));
1098	req.req_type = DP_ALLOCATE_PAYLOAD;
1099	req.u.allocate_payload.port_number = port_num;
1100	req.u.allocate_payload.vcpi = vcpi;
1101	req.u.allocate_payload.pbn = pbn;
1102	req.u.allocate_payload.number_sdp_streams = number_sdp_streams;
1103	memcpy(req.u.allocate_payload.sdp_stream_sink, sdp_stream_sink,
1104		   number_sdp_streams);
1105	drm_dp_encode_sideband_req(&req, msg);
1106	msg->path_msg = true;
1107}
1108
1109static void build_power_updown_phy(struct drm_dp_sideband_msg_tx *msg,
1110				   int port_num, bool power_up)
1111{
1112	struct drm_dp_sideband_msg_req_body req;
1113
1114	if (power_up)
1115		req.req_type = DP_POWER_UP_PHY;
1116	else
1117		req.req_type = DP_POWER_DOWN_PHY;
1118
1119	req.u.port_num.port_number = port_num;
1120	drm_dp_encode_sideband_req(&req, msg);
1121	msg->path_msg = true;
1122}
1123
1124static int drm_dp_mst_assign_payload_id(struct drm_dp_mst_topology_mgr *mgr,
1125					struct drm_dp_vcpi *vcpi)
1126{
1127	int ret, vcpi_ret;
1128
1129	mutex_lock(&mgr->payload_lock);
1130	ret = find_first_zero_bit(&mgr->payload_mask, mgr->max_payloads + 1);
1131	if (ret > mgr->max_payloads) {
1132		ret = -EINVAL;
1133		DRM_DEBUG_KMS("out of payload ids %d\n", ret);
1134		goto out_unlock;
1135	}
1136
1137	vcpi_ret = find_first_zero_bit(&mgr->vcpi_mask, mgr->max_payloads + 1);
1138	if (vcpi_ret > mgr->max_payloads) {
1139		ret = -EINVAL;
1140		DRM_DEBUG_KMS("out of vcpi ids %d\n", ret);
1141		goto out_unlock;
1142	}
1143
1144	set_bit(ret, &mgr->payload_mask);
1145	set_bit(vcpi_ret, &mgr->vcpi_mask);
1146	vcpi->vcpi = vcpi_ret + 1;
1147	mgr->proposed_vcpis[ret - 1] = vcpi;
1148out_unlock:
1149	mutex_unlock(&mgr->payload_lock);
1150	return ret;
1151}
1152
1153static void drm_dp_mst_put_payload_id(struct drm_dp_mst_topology_mgr *mgr,
1154				      int vcpi)
1155{
1156	int i;
1157
1158	if (vcpi == 0)
1159		return;
1160
1161	mutex_lock(&mgr->payload_lock);
1162	DRM_DEBUG_KMS("putting payload %d\n", vcpi);
1163	clear_bit(vcpi - 1, &mgr->vcpi_mask);
1164
1165	for (i = 0; i < mgr->max_payloads; i++) {
1166		if (mgr->proposed_vcpis[i] &&
1167		    mgr->proposed_vcpis[i]->vcpi == vcpi) {
1168			mgr->proposed_vcpis[i] = NULL;
1169			clear_bit(i + 1, &mgr->payload_mask);
1170		}
1171	}
1172	mutex_unlock(&mgr->payload_lock);
1173}
1174
1175static bool check_txmsg_state(struct drm_dp_mst_topology_mgr *mgr,
1176			      struct drm_dp_sideband_msg_tx *txmsg)
1177{
1178	unsigned int state;
1179
1180	/*
1181	 * All updates to txmsg->state are protected by mgr->qlock, and the two
1182	 * cases we check here are terminal states. For those the barriers
1183	 * provided by the wake_up/wait_event pair are enough.
1184	 */
1185	state = READ_ONCE(txmsg->state);
1186	return (state == DRM_DP_SIDEBAND_TX_RX ||
1187		state == DRM_DP_SIDEBAND_TX_TIMEOUT);
1188}
1189
1190static int drm_dp_mst_wait_tx_reply(struct drm_dp_mst_branch *mstb,
1191				    struct drm_dp_sideband_msg_tx *txmsg)
1192{
1193	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
1194	unsigned long wait_timeout = msecs_to_jiffies(4000);
1195	unsigned long wait_expires = jiffies + wait_timeout;
1196	int ret;
1197
1198	for (;;) {
1199		/*
1200		 * If the driver provides a way for this, change to
1201		 * poll-waiting for the MST reply interrupt if we didn't receive
1202		 * it for 50 msec. This would cater for cases where the HPD
1203		 * pulse signal got lost somewhere, even though the sink raised
1204		 * the corresponding MST interrupt correctly. One example is the
1205		 * Club 3D CAC-1557 TypeC -> DP adapter which for some reason
1206		 * filters out short pulses with a duration less than ~540 usec.
1207		 *
1208		 * The poll period is 50 msec to avoid missing an interrupt
1209		 * after the sink has cleared it (after a 110msec timeout
1210		 * since it raised the interrupt).
1211		 */
1212		ret = wait_event_timeout(mgr->tx_waitq,
1213					 check_txmsg_state(mgr, txmsg),
1214					 mgr->cbs->poll_hpd_irq ?
1215						msecs_to_jiffies(50) :
1216						wait_timeout);
1217
1218		if (ret || !mgr->cbs->poll_hpd_irq ||
1219		    time_after(jiffies, wait_expires))
1220			break;
1221
1222		mgr->cbs->poll_hpd_irq(mgr);
1223	}
1224
1225	mutex_lock(&mgr->qlock);
1226	if (ret > 0) {
1227		if (txmsg->state == DRM_DP_SIDEBAND_TX_TIMEOUT) {
1228			ret = -EIO;
1229			goto out;
1230		}
1231	} else {
1232		DRM_DEBUG_KMS("timedout msg send %p %d %d\n", txmsg, txmsg->state, txmsg->seqno);
1233
1234		/* dump some state */
1235		ret = -EIO;
1236
1237		/* remove from q */
1238		if (txmsg->state == DRM_DP_SIDEBAND_TX_QUEUED ||
1239		    txmsg->state == DRM_DP_SIDEBAND_TX_START_SEND ||
1240		    txmsg->state == DRM_DP_SIDEBAND_TX_SENT)
1241			list_del(&txmsg->next);
1242	}
1243out:
1244	if (unlikely(ret == -EIO) && drm_debug_enabled(DRM_UT_DP)) {
1245		struct drm_printer p = drm_debug_printer(DBG_PREFIX);
1246
1247		drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
1248	}
1249	mutex_unlock(&mgr->qlock);
1250
1251	drm_dp_mst_kick_tx(mgr);
1252	return ret;
1253}
1254
1255static struct drm_dp_mst_branch *drm_dp_add_mst_branch_device(u8 lct, u8 *rad)
1256{
1257	struct drm_dp_mst_branch *mstb;
1258
1259	mstb = kzalloc(sizeof(*mstb), GFP_KERNEL);
1260	if (!mstb)
1261		return NULL;
1262
1263	mstb->lct = lct;
1264	if (lct > 1)
1265		memcpy(mstb->rad, rad, lct / 2);
1266	INIT_LIST_HEAD(&mstb->ports);
1267	kref_init(&mstb->topology_kref);
1268	kref_init(&mstb->malloc_kref);
1269	return mstb;
1270}
1271
1272static void drm_dp_free_mst_branch_device(struct kref *kref)
1273{
1274	struct drm_dp_mst_branch *mstb =
1275		container_of(kref, struct drm_dp_mst_branch, malloc_kref);
1276
1277	if (mstb->port_parent)
1278		drm_dp_mst_put_port_malloc(mstb->port_parent);
1279
1280	kfree(mstb);
1281}
1282
1283/**
1284 * DOC: Branch device and port refcounting
1285 *
1286 * Topology refcount overview
1287 * ~~~~~~~~~~~~~~~~~~~~~~~~~~
1288 *
1289 * The refcounting schemes for &struct drm_dp_mst_branch and &struct
1290 * drm_dp_mst_port are somewhat unusual. Both ports and branch devices have
1291 * two different kinds of refcounts: topology refcounts, and malloc refcounts.
1292 *
1293 * Topology refcounts are not exposed to drivers, and are handled internally
1294 * by the DP MST helpers. The helpers use them in order to prevent the
1295 * in-memory topology state from being changed in the middle of critical
1296 * operations like changing the internal state of payload allocations. This
1297 * means each branch and port will be considered to be connected to the rest
1298 * of the topology until its topology refcount reaches zero. Additionally,
1299 * for ports this means that their associated &struct drm_connector will stay
1300 * registered with userspace until the port's refcount reaches 0.
1301 *
1302 * Malloc refcount overview
1303 * ~~~~~~~~~~~~~~~~~~~~~~~~
1304 *
1305 * Malloc references are used to keep a &struct drm_dp_mst_port or &struct
1306 * drm_dp_mst_branch allocated even after all of its topology references have
1307 * been dropped, so that the driver or MST helpers can safely access each
1308 * branch's last known state before it was disconnected from the topology.
1309 * When the malloc refcount of a port or branch reaches 0, the memory
1310 * allocation containing the &struct drm_dp_mst_branch or &struct
1311 * drm_dp_mst_port respectively will be freed.
1312 *
1313 * For &struct drm_dp_mst_branch, malloc refcounts are not currently exposed
1314 * to drivers. As of writing this documentation, there are no drivers that
1315 * have a usecase for accessing &struct drm_dp_mst_branch outside of the MST
1316 * helpers. Exposing this API to drivers in a race-free manner would take more
1317 * tweaking of the refcounting scheme, however patches are welcome provided
1318 * there is a legitimate driver usecase for this.
1319 *
1320 * Refcount relationships in a topology
1321 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1322 *
1323 * Let's take a look at why the relationship between topology and malloc
1324 * refcounts is designed the way it is.
1325 *
1326 * .. kernel-figure:: dp-mst/topology-figure-1.dot
1327 *
1328 *    An example of topology and malloc refs in a DP MST topology with two
1329 *    active payloads. Topology refcount increments are indicated by solid
1330 *    lines, and malloc refcount increments are indicated by dashed lines.
1331 *    Each starts from the branch which incremented the refcount, and ends at
1332 *    the branch to which the refcount belongs to, i.e. the arrow points the
1333 *    same way as the C pointers used to reference a structure.
1334 *
1335 * As you can see in the above figure, every branch increments the topology
1336 * refcount of its children, and increments the malloc refcount of its
1337 * parent. Additionally, every payload increments the malloc refcount of its
1338 * assigned port by 1.
1339 *
1340 * So, what would happen if MSTB #3 from the above figure was unplugged from
1341 * the system, but the driver hadn't yet removed payload #2 from port #3? The
1342 * topology would start to look like the figure below.
1343 *
1344 * .. kernel-figure:: dp-mst/topology-figure-2.dot
1345 *
1346 *    Ports and branch devices which have been released from memory are
1347 *    colored grey, and references which have been removed are colored red.
1348 *
1349 * Whenever a port or branch device's topology refcount reaches zero, it will
1350 * decrement the topology refcounts of all its children, the malloc refcount
1351 * of its parent, and finally its own malloc refcount. For MSTB #4 and port
1352 * #4, this means they both have been disconnected from the topology and freed
1353 * from memory. But, because payload #2 is still holding a reference to port
1354 * #3, port #3 is removed from the topology but its &struct drm_dp_mst_port
1355 * is still accessible from memory. This also means port #3 has not yet
1356 * decremented the malloc refcount of MSTB #3, so its &struct
1357 * drm_dp_mst_branch will also stay allocated in memory until port #3's
1358 * malloc refcount reaches 0.
1359 *
1360 * This relationship is necessary because in order to release payload #2, we
1361 * need to be able to figure out the last relative of port #3 that's still
1362 * connected to the topology. In this case, we would travel up the topology as
1363 * shown below.
1364 *
1365 * .. kernel-figure:: dp-mst/topology-figure-3.dot
1366 *
1367 * And finally, remove payload #2 by communicating with port #2 through
1368 * sideband transactions.
1369 */
1370
1371/**
1372 * drm_dp_mst_get_mstb_malloc() - Increment the malloc refcount of a branch
1373 * device
1374 * @mstb: The &struct drm_dp_mst_branch to increment the malloc refcount of
1375 *
1376 * Increments &drm_dp_mst_branch.malloc_kref. When
1377 * &drm_dp_mst_branch.malloc_kref reaches 0, the memory allocation for @mstb
1378 * will be released and @mstb may no longer be used.
1379 *
1380 * See also: drm_dp_mst_put_mstb_malloc()
1381 */
1382static void
1383drm_dp_mst_get_mstb_malloc(struct drm_dp_mst_branch *mstb)
1384{
1385	kref_get(&mstb->malloc_kref);
1386	DRM_DEBUG("mstb %p (%d)\n", mstb, kref_read(&mstb->malloc_kref));
1387}
1388
1389/**
1390 * drm_dp_mst_put_mstb_malloc() - Decrement the malloc refcount of a branch
1391 * device
1392 * @mstb: The &struct drm_dp_mst_branch to decrement the malloc refcount of
1393 *
1394 * Decrements &drm_dp_mst_branch.malloc_kref. When
1395 * &drm_dp_mst_branch.malloc_kref reaches 0, the memory allocation for @mstb
1396 * will be released and @mstb may no longer be used.
1397 *
1398 * See also: drm_dp_mst_get_mstb_malloc()
1399 */
1400static void
1401drm_dp_mst_put_mstb_malloc(struct drm_dp_mst_branch *mstb)
1402{
1403	DRM_DEBUG("mstb %p (%d)\n", mstb, kref_read(&mstb->malloc_kref) - 1);
1404	kref_put(&mstb->malloc_kref, drm_dp_free_mst_branch_device);
1405}
1406
1407static void drm_dp_free_mst_port(struct kref *kref)
1408{
1409	struct drm_dp_mst_port *port =
1410		container_of(kref, struct drm_dp_mst_port, malloc_kref);
1411
1412	drm_dp_mst_put_mstb_malloc(port->parent);
1413	kfree(port);
1414}
1415
1416/**
1417 * drm_dp_mst_get_port_malloc() - Increment the malloc refcount of an MST port
1418 * @port: The &struct drm_dp_mst_port to increment the malloc refcount of
1419 *
1420 * Increments &drm_dp_mst_port.malloc_kref. When &drm_dp_mst_port.malloc_kref
1421 * reaches 0, the memory allocation for @port will be released and @port may
1422 * no longer be used.
1423 *
1424 * Because @port could potentially be freed at any time by the DP MST helpers
1425 * if &drm_dp_mst_port.malloc_kref reaches 0, including during a call to this
1426 * function, drivers that which to make use of &struct drm_dp_mst_port should
1427 * ensure that they grab at least one main malloc reference to their MST ports
1428 * in &drm_dp_mst_topology_cbs.add_connector. This callback is called before
1429 * there is any chance for &drm_dp_mst_port.malloc_kref to reach 0.
1430 *
1431 * See also: drm_dp_mst_put_port_malloc()
1432 */
1433void
1434drm_dp_mst_get_port_malloc(struct drm_dp_mst_port *port)
1435{
1436	kref_get(&port->malloc_kref);
1437	DRM_DEBUG("port %p (%d)\n", port, kref_read(&port->malloc_kref));
1438}
1439EXPORT_SYMBOL(drm_dp_mst_get_port_malloc);
1440
1441/**
1442 * drm_dp_mst_put_port_malloc() - Decrement the malloc refcount of an MST port
1443 * @port: The &struct drm_dp_mst_port to decrement the malloc refcount of
1444 *
1445 * Decrements &drm_dp_mst_port.malloc_kref. When &drm_dp_mst_port.malloc_kref
1446 * reaches 0, the memory allocation for @port will be released and @port may
1447 * no longer be used.
1448 *
1449 * See also: drm_dp_mst_get_port_malloc()
1450 */
1451void
1452drm_dp_mst_put_port_malloc(struct drm_dp_mst_port *port)
1453{
1454	DRM_DEBUG("port %p (%d)\n", port, kref_read(&port->malloc_kref) - 1);
1455	kref_put(&port->malloc_kref, drm_dp_free_mst_port);
1456}
1457EXPORT_SYMBOL(drm_dp_mst_put_port_malloc);
1458
1459#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
1460
1461#define STACK_DEPTH 8
1462
1463static noinline void
1464__topology_ref_save(struct drm_dp_mst_topology_mgr *mgr,
1465		    struct drm_dp_mst_topology_ref_history *history,
1466		    enum drm_dp_mst_topology_ref_type type)
1467{
1468	struct drm_dp_mst_topology_ref_entry *entry = NULL;
1469	depot_stack_handle_t backtrace;
1470	ulong stack_entries[STACK_DEPTH];
1471	uint n;
1472	int i;
1473
1474	n = stack_trace_save(stack_entries, ARRAY_SIZE(stack_entries), 1);
1475	backtrace = stack_depot_save(stack_entries, n, GFP_KERNEL);
1476	if (!backtrace)
1477		return;
1478
1479	/* Try to find an existing entry for this backtrace */
1480	for (i = 0; i < history->len; i++) {
1481		if (history->entries[i].backtrace == backtrace) {
1482			entry = &history->entries[i];
1483			break;
1484		}
1485	}
1486
1487	/* Otherwise add one */
1488	if (!entry) {
1489		struct drm_dp_mst_topology_ref_entry *new;
1490		int new_len = history->len + 1;
1491
1492		new = krealloc(history->entries, sizeof(*new) * new_len,
1493			       GFP_KERNEL);
1494		if (!new)
1495			return;
1496
1497		entry = &new[history->len];
1498		history->len = new_len;
1499		history->entries = new;
1500
1501		entry->backtrace = backtrace;
1502		entry->type = type;
1503		entry->count = 0;
1504	}
1505	entry->count++;
1506	entry->ts_nsec = ktime_get_ns();
1507}
1508
1509static int
1510topology_ref_history_cmp(const void *a, const void *b)
1511{
1512	const struct drm_dp_mst_topology_ref_entry *entry_a = a, *entry_b = b;
1513
1514	if (entry_a->ts_nsec > entry_b->ts_nsec)
1515		return 1;
1516	else if (entry_a->ts_nsec < entry_b->ts_nsec)
1517		return -1;
1518	else
1519		return 0;
1520}
1521
1522static inline const char *
1523topology_ref_type_to_str(enum drm_dp_mst_topology_ref_type type)
1524{
1525	if (type == DRM_DP_MST_TOPOLOGY_REF_GET)
1526		return "get";
1527	else
1528		return "put";
1529}
1530
1531static void
1532__dump_topology_ref_history(struct drm_dp_mst_topology_ref_history *history,
1533			    void *ptr, const char *type_str)
1534{
1535	struct drm_printer p = drm_debug_printer(DBG_PREFIX);
1536	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
1537	int i;
1538
1539	if (!buf)
1540		return;
1541
1542	if (!history->len)
1543		goto out;
1544
1545	/* First, sort the list so that it goes from oldest to newest
1546	 * reference entry
1547	 */
1548	sort(history->entries, history->len, sizeof(*history->entries),
1549	     topology_ref_history_cmp, NULL);
1550
1551	drm_printf(&p, "%s (%p) topology count reached 0, dumping history:\n",
1552		   type_str, ptr);
1553
1554	for (i = 0; i < history->len; i++) {
1555		const struct drm_dp_mst_topology_ref_entry *entry =
1556			&history->entries[i];
1557		ulong *entries;
1558		uint nr_entries;
1559		u64 ts_nsec = entry->ts_nsec;
1560		u32 rem_nsec = do_div(ts_nsec, 1000000000);
1561
1562		nr_entries = stack_depot_fetch(entry->backtrace, &entries);
1563		stack_trace_snprint(buf, PAGE_SIZE, entries, nr_entries, 4);
1564
1565		drm_printf(&p, "  %d %ss (last at %5llu.%06u):\n%s",
1566			   entry->count,
1567			   topology_ref_type_to_str(entry->type),
1568			   ts_nsec, rem_nsec / 1000, buf);
1569	}
1570
1571	/* Now free the history, since this is the only time we expose it */
1572	kfree(history->entries);
1573out:
1574	kfree(buf);
1575}
1576
1577static __always_inline void
1578drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb)
1579{
1580	__dump_topology_ref_history(&mstb->topology_ref_history, mstb,
1581				    "MSTB");
1582}
1583
1584static __always_inline void
1585drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port)
1586{
1587	__dump_topology_ref_history(&port->topology_ref_history, port,
1588				    "Port");
1589}
1590
1591static __always_inline void
1592save_mstb_topology_ref(struct drm_dp_mst_branch *mstb,
1593		       enum drm_dp_mst_topology_ref_type type)
1594{
1595	__topology_ref_save(mstb->mgr, &mstb->topology_ref_history, type);
1596}
1597
1598static __always_inline void
1599save_port_topology_ref(struct drm_dp_mst_port *port,
1600		       enum drm_dp_mst_topology_ref_type type)
1601{
1602	__topology_ref_save(port->mgr, &port->topology_ref_history, type);
1603}
1604
1605static inline void
1606topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr)
1607{
1608	mutex_lock(&mgr->topology_ref_history_lock);
1609}
1610
1611static inline void
1612topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr)
1613{
1614	mutex_unlock(&mgr->topology_ref_history_lock);
1615}
1616#else
1617static inline void
1618topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr) {}
1619static inline void
1620topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr) {}
1621static inline void
1622drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb) {}
1623static inline void
1624drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port) {}
1625#define save_mstb_topology_ref(mstb, type)
1626#define save_port_topology_ref(port, type)
1627#endif
1628
1629static void drm_dp_destroy_mst_branch_device(struct kref *kref)
1630{
1631	struct drm_dp_mst_branch *mstb =
1632		container_of(kref, struct drm_dp_mst_branch, topology_kref);
1633	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
1634
1635	drm_dp_mst_dump_mstb_topology_history(mstb);
1636
1637	INIT_LIST_HEAD(&mstb->destroy_next);
1638
1639	/*
1640	 * This can get called under mgr->mutex, so we need to perform the
1641	 * actual destruction of the mstb in another worker
1642	 */
1643	mutex_lock(&mgr->delayed_destroy_lock);
1644	list_add(&mstb->destroy_next, &mgr->destroy_branch_device_list);
1645	mutex_unlock(&mgr->delayed_destroy_lock);
1646	queue_work(mgr->delayed_destroy_wq, &mgr->delayed_destroy_work);
1647}
1648
1649/**
1650 * drm_dp_mst_topology_try_get_mstb() - Increment the topology refcount of a
1651 * branch device unless it's zero
1652 * @mstb: &struct drm_dp_mst_branch to increment the topology refcount of
1653 *
1654 * Attempts to grab a topology reference to @mstb, if it hasn't yet been
1655 * removed from the topology (e.g. &drm_dp_mst_branch.topology_kref has
1656 * reached 0). Holding a topology reference implies that a malloc reference
1657 * will be held to @mstb as long as the user holds the topology reference.
1658 *
1659 * Care should be taken to ensure that the user has at least one malloc
1660 * reference to @mstb. If you already have a topology reference to @mstb, you
1661 * should use drm_dp_mst_topology_get_mstb() instead.
1662 *
1663 * See also:
1664 * drm_dp_mst_topology_get_mstb()
1665 * drm_dp_mst_topology_put_mstb()
1666 *
1667 * Returns:
1668 * * 1: A topology reference was grabbed successfully
1669 * * 0: @port is no longer in the topology, no reference was grabbed
1670 */
1671static int __must_check
1672drm_dp_mst_topology_try_get_mstb(struct drm_dp_mst_branch *mstb)
1673{
1674	int ret;
1675
1676	topology_ref_history_lock(mstb->mgr);
1677	ret = kref_get_unless_zero(&mstb->topology_kref);
1678	if (ret) {
1679		DRM_DEBUG("mstb %p (%d)\n",
1680			  mstb, kref_read(&mstb->topology_kref));
1681		save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET);
1682	}
1683
1684	topology_ref_history_unlock(mstb->mgr);
1685
1686	return ret;
1687}
1688
1689/**
1690 * drm_dp_mst_topology_get_mstb() - Increment the topology refcount of a
1691 * branch device
1692 * @mstb: The &struct drm_dp_mst_branch to increment the topology refcount of
1693 *
1694 * Increments &drm_dp_mst_branch.topology_refcount without checking whether or
1695 * not it's already reached 0. This is only valid to use in scenarios where
1696 * you are already guaranteed to have at least one active topology reference
1697 * to @mstb. Otherwise, drm_dp_mst_topology_try_get_mstb() must be used.
1698 *
1699 * See also:
1700 * drm_dp_mst_topology_try_get_mstb()
1701 * drm_dp_mst_topology_put_mstb()
1702 */
1703static void drm_dp_mst_topology_get_mstb(struct drm_dp_mst_branch *mstb)
1704{
1705	topology_ref_history_lock(mstb->mgr);
1706
1707	save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET);
1708	WARN_ON(kref_read(&mstb->topology_kref) == 0);
1709	kref_get(&mstb->topology_kref);
1710	DRM_DEBUG("mstb %p (%d)\n", mstb, kref_read(&mstb->topology_kref));
1711
1712	topology_ref_history_unlock(mstb->mgr);
1713}
1714
1715/**
1716 * drm_dp_mst_topology_put_mstb() - release a topology reference to a branch
1717 * device
1718 * @mstb: The &struct drm_dp_mst_branch to release the topology reference from
1719 *
1720 * Releases a topology reference from @mstb by decrementing
1721 * &drm_dp_mst_branch.topology_kref.
1722 *
1723 * See also:
1724 * drm_dp_mst_topology_try_get_mstb()
1725 * drm_dp_mst_topology_get_mstb()
1726 */
1727static void
1728drm_dp_mst_topology_put_mstb(struct drm_dp_mst_branch *mstb)
1729{
1730	topology_ref_history_lock(mstb->mgr);
1731
1732	DRM_DEBUG("mstb %p (%d)\n",
1733		  mstb, kref_read(&mstb->topology_kref) - 1);
1734	save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_PUT);
1735
1736	topology_ref_history_unlock(mstb->mgr);
1737	kref_put(&mstb->topology_kref, drm_dp_destroy_mst_branch_device);
1738}
1739
1740static void drm_dp_destroy_port(struct kref *kref)
1741{
1742	struct drm_dp_mst_port *port =
1743		container_of(kref, struct drm_dp_mst_port, topology_kref);
1744	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
1745
1746	drm_dp_mst_dump_port_topology_history(port);
1747
1748	/* There's nothing that needs locking to destroy an input port yet */
1749	if (port->input) {
1750		drm_dp_mst_put_port_malloc(port);
1751		return;
1752	}
1753
1754	kfree(port->cached_edid);
1755
1756	/*
1757	 * we can't destroy the connector here, as we might be holding the
1758	 * mode_config.mutex from an EDID retrieval
1759	 */
1760	mutex_lock(&mgr->delayed_destroy_lock);
1761	list_add(&port->next, &mgr->destroy_port_list);
1762	mutex_unlock(&mgr->delayed_destroy_lock);
1763	queue_work(mgr->delayed_destroy_wq, &mgr->delayed_destroy_work);
1764}
1765
1766/**
1767 * drm_dp_mst_topology_try_get_port() - Increment the topology refcount of a
1768 * port unless it's zero
1769 * @port: &struct drm_dp_mst_port to increment the topology refcount of
1770 *
1771 * Attempts to grab a topology reference to @port, if it hasn't yet been
1772 * removed from the topology (e.g. &drm_dp_mst_port.topology_kref has reached
1773 * 0). Holding a topology reference implies that a malloc reference will be
1774 * held to @port as long as the user holds the topology reference.
1775 *
1776 * Care should be taken to ensure that the user has at least one malloc
1777 * reference to @port. If you already have a topology reference to @port, you
1778 * should use drm_dp_mst_topology_get_port() instead.
1779 *
1780 * See also:
1781 * drm_dp_mst_topology_get_port()
1782 * drm_dp_mst_topology_put_port()
1783 *
1784 * Returns:
1785 * * 1: A topology reference was grabbed successfully
1786 * * 0: @port is no longer in the topology, no reference was grabbed
1787 */
1788static int __must_check
1789drm_dp_mst_topology_try_get_port(struct drm_dp_mst_port *port)
1790{
1791	int ret;
1792
1793	topology_ref_history_lock(port->mgr);
1794	ret = kref_get_unless_zero(&port->topology_kref);
1795	if (ret) {
1796		DRM_DEBUG("port %p (%d)\n",
1797			  port, kref_read(&port->topology_kref));
1798		save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET);
1799	}
1800
1801	topology_ref_history_unlock(port->mgr);
1802	return ret;
1803}
1804
1805/**
1806 * drm_dp_mst_topology_get_port() - Increment the topology refcount of a port
1807 * @port: The &struct drm_dp_mst_port to increment the topology refcount of
1808 *
1809 * Increments &drm_dp_mst_port.topology_refcount without checking whether or
1810 * not it's already reached 0. This is only valid to use in scenarios where
1811 * you are already guaranteed to have at least one active topology reference
1812 * to @port. Otherwise, drm_dp_mst_topology_try_get_port() must be used.
1813 *
1814 * See also:
1815 * drm_dp_mst_topology_try_get_port()
1816 * drm_dp_mst_topology_put_port()
1817 */
1818static void drm_dp_mst_topology_get_port(struct drm_dp_mst_port *port)
1819{
1820	topology_ref_history_lock(port->mgr);
1821
1822	WARN_ON(kref_read(&port->topology_kref) == 0);
1823	kref_get(&port->topology_kref);
1824	DRM_DEBUG("port %p (%d)\n", port, kref_read(&port->topology_kref));
1825	save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET);
1826
1827	topology_ref_history_unlock(port->mgr);
1828}
1829
1830/**
1831 * drm_dp_mst_topology_put_port() - release a topology reference to a port
1832 * @port: The &struct drm_dp_mst_port to release the topology reference from
1833 *
1834 * Releases a topology reference from @port by decrementing
1835 * &drm_dp_mst_port.topology_kref.
1836 *
1837 * See also:
1838 * drm_dp_mst_topology_try_get_port()
1839 * drm_dp_mst_topology_get_port()
1840 */
1841static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port)
1842{
1843	topology_ref_history_lock(port->mgr);
1844
1845	DRM_DEBUG("port %p (%d)\n",
1846		  port, kref_read(&port->topology_kref) - 1);
1847	save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_PUT);
1848
1849	topology_ref_history_unlock(port->mgr);
1850	kref_put(&port->topology_kref, drm_dp_destroy_port);
1851}
1852
1853static struct drm_dp_mst_branch *
1854drm_dp_mst_topology_get_mstb_validated_locked(struct drm_dp_mst_branch *mstb,
1855					      struct drm_dp_mst_branch *to_find)
1856{
1857	struct drm_dp_mst_port *port;
1858	struct drm_dp_mst_branch *rmstb;
1859
1860	if (to_find == mstb)
1861		return mstb;
1862
1863	list_for_each_entry(port, &mstb->ports, next) {
1864		if (port->mstb) {
1865			rmstb = drm_dp_mst_topology_get_mstb_validated_locked(
1866			    port->mstb, to_find);
1867			if (rmstb)
1868				return rmstb;
1869		}
1870	}
1871	return NULL;
1872}
1873
1874static struct drm_dp_mst_branch *
1875drm_dp_mst_topology_get_mstb_validated(struct drm_dp_mst_topology_mgr *mgr,
1876				       struct drm_dp_mst_branch *mstb)
1877{
1878	struct drm_dp_mst_branch *rmstb = NULL;
1879
1880	mutex_lock(&mgr->lock);
1881	if (mgr->mst_primary) {
1882		rmstb = drm_dp_mst_topology_get_mstb_validated_locked(
1883		    mgr->mst_primary, mstb);
1884
1885		if (rmstb && !drm_dp_mst_topology_try_get_mstb(rmstb))
1886			rmstb = NULL;
1887	}
1888	mutex_unlock(&mgr->lock);
1889	return rmstb;
1890}
1891
1892static struct drm_dp_mst_port *
1893drm_dp_mst_topology_get_port_validated_locked(struct drm_dp_mst_branch *mstb,
1894					      struct drm_dp_mst_port *to_find)
1895{
1896	struct drm_dp_mst_port *port, *mport;
1897
1898	list_for_each_entry(port, &mstb->ports, next) {
1899		if (port == to_find)
1900			return port;
1901
1902		if (port->mstb) {
1903			mport = drm_dp_mst_topology_get_port_validated_locked(
1904			    port->mstb, to_find);
1905			if (mport)
1906				return mport;
1907		}
1908	}
1909	return NULL;
1910}
1911
1912static struct drm_dp_mst_port *
1913drm_dp_mst_topology_get_port_validated(struct drm_dp_mst_topology_mgr *mgr,
1914				       struct drm_dp_mst_port *port)
1915{
1916	struct drm_dp_mst_port *rport = NULL;
1917
1918	mutex_lock(&mgr->lock);
1919	if (mgr->mst_primary) {
1920		rport = drm_dp_mst_topology_get_port_validated_locked(
1921		    mgr->mst_primary, port);
1922
1923		if (rport && !drm_dp_mst_topology_try_get_port(rport))
1924			rport = NULL;
1925	}
1926	mutex_unlock(&mgr->lock);
1927	return rport;
1928}
1929
1930static struct drm_dp_mst_port *drm_dp_get_port(struct drm_dp_mst_branch *mstb, u8 port_num)
1931{
1932	struct drm_dp_mst_port *port;
1933	int ret;
1934
1935	list_for_each_entry(port, &mstb->ports, next) {
1936		if (port->port_num == port_num) {
1937			ret = drm_dp_mst_topology_try_get_port(port);
1938			return ret ? port : NULL;
1939		}
1940	}
1941
1942	return NULL;
1943}
1944
1945/*
1946 * calculate a new RAD for this MST branch device
1947 * if parent has an LCT of 2 then it has 1 nibble of RAD,
1948 * if parent has an LCT of 3 then it has 2 nibbles of RAD,
1949 */
1950static u8 drm_dp_calculate_rad(struct drm_dp_mst_port *port,
1951				 u8 *rad)
1952{
1953	int parent_lct = port->parent->lct;
1954	int shift = 4;
1955	int idx = (parent_lct - 1) / 2;
1956
1957	if (parent_lct > 1) {
1958		memcpy(rad, port->parent->rad, idx + 1);
1959		shift = (parent_lct % 2) ? 4 : 0;
1960	} else
1961		rad[0] = 0;
1962
1963	rad[idx] |= port->port_num << shift;
1964	return parent_lct + 1;
1965}
1966
1967static bool drm_dp_mst_is_end_device(u8 pdt, bool mcs)
1968{
1969	switch (pdt) {
1970	case DP_PEER_DEVICE_DP_LEGACY_CONV:
1971	case DP_PEER_DEVICE_SST_SINK:
1972		return true;
1973	case DP_PEER_DEVICE_MST_BRANCHING:
1974		/* For sst branch device */
1975		if (!mcs)
1976			return true;
1977
1978		return false;
1979	}
1980	return true;
1981}
1982
1983static int
1984drm_dp_port_set_pdt(struct drm_dp_mst_port *port, u8 new_pdt,
1985		    bool new_mcs)
1986{
1987	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
1988	struct drm_dp_mst_branch *mstb;
1989	u8 rad[8], lct;
1990	int ret = 0;
1991
1992	if (port->pdt == new_pdt && port->mcs == new_mcs)
1993		return 0;
1994
1995	/* Teardown the old pdt, if there is one */
1996	if (port->pdt != DP_PEER_DEVICE_NONE) {
1997		if (drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
1998			/*
1999			 * If the new PDT would also have an i2c bus,
2000			 * don't bother with reregistering it
2001			 */
2002			if (new_pdt != DP_PEER_DEVICE_NONE &&
2003			    drm_dp_mst_is_end_device(new_pdt, new_mcs)) {
2004				port->pdt = new_pdt;
2005				port->mcs = new_mcs;
2006				return 0;
2007			}
2008
2009			/* remove i2c over sideband */
2010			drm_dp_mst_unregister_i2c_bus(port);
2011		} else {
2012			mutex_lock(&mgr->lock);
2013			drm_dp_mst_topology_put_mstb(port->mstb);
2014			port->mstb = NULL;
2015			mutex_unlock(&mgr->lock);
2016		}
2017	}
2018
2019	port->pdt = new_pdt;
2020	port->mcs = new_mcs;
2021
2022	if (port->pdt != DP_PEER_DEVICE_NONE) {
2023		if (drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
2024			/* add i2c over sideband */
2025			ret = drm_dp_mst_register_i2c_bus(port);
2026		} else {
2027			lct = drm_dp_calculate_rad(port, rad);
2028			mstb = drm_dp_add_mst_branch_device(lct, rad);
2029			if (!mstb) {
2030				ret = -ENOMEM;
2031				DRM_ERROR("Failed to create MSTB for port %p",
2032					  port);
2033				goto out;
2034			}
2035
2036			mutex_lock(&mgr->lock);
2037			port->mstb = mstb;
2038			mstb->mgr = port->mgr;
2039			mstb->port_parent = port;
2040
2041			/*
2042			 * Make sure this port's memory allocation stays
2043			 * around until its child MSTB releases it
2044			 */
2045			drm_dp_mst_get_port_malloc(port);
2046			mutex_unlock(&mgr->lock);
2047
2048			/* And make sure we send a link address for this */
2049			ret = 1;
2050		}
2051	}
2052
2053out:
2054	if (ret < 0)
2055		port->pdt = DP_PEER_DEVICE_NONE;
2056	return ret;
2057}
2058
2059/**
2060 * drm_dp_mst_dpcd_read() - read a series of bytes from the DPCD via sideband
2061 * @aux: Fake sideband AUX CH
2062 * @offset: address of the (first) register to read
2063 * @buffer: buffer to store the register values
2064 * @size: number of bytes in @buffer
2065 *
2066 * Performs the same functionality for remote devices via
2067 * sideband messaging as drm_dp_dpcd_read() does for local
2068 * devices via actual AUX CH.
2069 *
2070 * Return: Number of bytes read, or negative error code on failure.
2071 */
2072ssize_t drm_dp_mst_dpcd_read(struct drm_dp_aux *aux,
2073			     unsigned int offset, void *buffer, size_t size)
2074{
2075	struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port,
2076						    aux);
2077
2078	return drm_dp_send_dpcd_read(port->mgr, port,
2079				     offset, size, buffer);
2080}
2081
2082/**
2083 * drm_dp_mst_dpcd_write() - write a series of bytes to the DPCD via sideband
2084 * @aux: Fake sideband AUX CH
2085 * @offset: address of the (first) register to write
2086 * @buffer: buffer containing the values to write
2087 * @size: number of bytes in @buffer
2088 *
2089 * Performs the same functionality for remote devices via
2090 * sideband messaging as drm_dp_dpcd_write() does for local
2091 * devices via actual AUX CH.
2092 *
2093 * Return: number of bytes written on success, negative error code on failure.
2094 */
2095ssize_t drm_dp_mst_dpcd_write(struct drm_dp_aux *aux,
2096			      unsigned int offset, void *buffer, size_t size)
2097{
2098	struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port,
2099						    aux);
2100
2101	return drm_dp_send_dpcd_write(port->mgr, port,
2102				      offset, size, buffer);
2103}
2104
2105static int drm_dp_check_mstb_guid(struct drm_dp_mst_branch *mstb, u8 *guid)
2106{
2107	int ret = 0;
2108
2109	memcpy(mstb->guid, guid, 16);
2110
2111	if (!drm_dp_validate_guid(mstb->mgr, mstb->guid)) {
2112		if (mstb->port_parent) {
2113			ret = drm_dp_send_dpcd_write(mstb->mgr,
2114						     mstb->port_parent,
2115						     DP_GUID, 16, mstb->guid);
2116		} else {
2117			ret = drm_dp_dpcd_write(mstb->mgr->aux,
2118						DP_GUID, mstb->guid, 16);
2119		}
2120	}
2121
2122	if (ret < 16 && ret > 0)
2123		return -EPROTO;
2124
2125	return ret == 16 ? 0 : ret;
2126}
2127
2128static void build_mst_prop_path(const struct drm_dp_mst_branch *mstb,
2129				int pnum,
2130				char *proppath,
2131				size_t proppath_size)
2132{
2133	int i;
2134	char temp[8];
2135
2136	snprintf(proppath, proppath_size, "mst:%d", mstb->mgr->conn_base_id);
2137	for (i = 0; i < (mstb->lct - 1); i++) {
2138		int shift = (i % 2) ? 0 : 4;
2139		int port_num = (mstb->rad[i / 2] >> shift) & 0xf;
2140
2141		snprintf(temp, sizeof(temp), "-%d", port_num);
2142		strlcat(proppath, temp, proppath_size);
2143	}
2144	snprintf(temp, sizeof(temp), "-%d", pnum);
2145	strlcat(proppath, temp, proppath_size);
2146}
2147
2148/**
2149 * drm_dp_mst_connector_late_register() - Late MST connector registration
2150 * @connector: The MST connector
2151 * @port: The MST port for this connector
2152 *
2153 * Helper to register the remote aux device for this MST port. Drivers should
2154 * call this from their mst connector's late_register hook to enable MST aux
2155 * devices.
2156 *
2157 * Return: 0 on success, negative error code on failure.
2158 */
2159int drm_dp_mst_connector_late_register(struct drm_connector *connector,
2160				       struct drm_dp_mst_port *port)
2161{
2162	DRM_DEBUG_KMS("registering %s remote bus for %s\n",
2163		      port->aux.name, connector->kdev->kobj.name);
2164
2165	port->aux.dev = connector->kdev;
2166	return drm_dp_aux_register_devnode(&port->aux);
2167}
2168EXPORT_SYMBOL(drm_dp_mst_connector_late_register);
2169
2170/**
2171 * drm_dp_mst_connector_early_unregister() - Early MST connector unregistration
2172 * @connector: The MST connector
2173 * @port: The MST port for this connector
2174 *
2175 * Helper to unregister the remote aux device for this MST port, registered by
2176 * drm_dp_mst_connector_late_register(). Drivers should call this from their mst
2177 * connector's early_unregister hook.
2178 */
2179void drm_dp_mst_connector_early_unregister(struct drm_connector *connector,
2180					   struct drm_dp_mst_port *port)
2181{
2182	DRM_DEBUG_KMS("unregistering %s remote bus for %s\n",
2183		      port->aux.name, connector->kdev->kobj.name);
2184	drm_dp_aux_unregister_devnode(&port->aux);
2185}
2186EXPORT_SYMBOL(drm_dp_mst_connector_early_unregister);
2187
2188static void
2189drm_dp_mst_port_add_connector(struct drm_dp_mst_branch *mstb,
2190			      struct drm_dp_mst_port *port)
2191{
2192	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
2193	char proppath[255];
2194	int ret;
2195
2196	build_mst_prop_path(mstb, port->port_num, proppath, sizeof(proppath));
2197	port->connector = mgr->cbs->add_connector(mgr, port, proppath);
2198	if (!port->connector) {
2199		ret = -ENOMEM;
2200		goto error;
2201	}
2202
2203	if (port->pdt != DP_PEER_DEVICE_NONE &&
2204	    drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
2205		port->cached_edid = drm_get_edid(port->connector,
2206						 &port->aux.ddc);
2207		drm_connector_set_tile_property(port->connector);
2208	}
2209
2210	drm_connector_register(port->connector);
2211	return;
2212
2213error:
2214	DRM_ERROR("Failed to create connector for port %p: %d\n", port, ret);
2215}
2216
2217/*
2218 * Drop a topology reference, and unlink the port from the in-memory topology
2219 * layout
2220 */
2221static void
2222drm_dp_mst_topology_unlink_port(struct drm_dp_mst_topology_mgr *mgr,
2223				struct drm_dp_mst_port *port)
2224{
2225	mutex_lock(&mgr->lock);
2226	port->parent->num_ports--;
2227	list_del(&port->next);
2228	mutex_unlock(&mgr->lock);
2229	drm_dp_mst_topology_put_port(port);
2230}
2231
2232static struct drm_dp_mst_port *
2233drm_dp_mst_add_port(struct drm_device *dev,
2234		    struct drm_dp_mst_topology_mgr *mgr,
2235		    struct drm_dp_mst_branch *mstb, u8 port_number)
2236{
2237	struct drm_dp_mst_port *port = kzalloc(sizeof(*port), GFP_KERNEL);
2238
2239	if (!port)
2240		return NULL;
2241
2242	kref_init(&port->topology_kref);
2243	kref_init(&port->malloc_kref);
2244	port->parent = mstb;
2245	port->port_num = port_number;
2246	port->mgr = mgr;
2247	port->aux.name = "DPMST";
2248	port->aux.dev = dev->dev;
2249	port->aux.is_remote = true;
2250
2251	/* initialize the MST downstream port's AUX crc work queue */
2252	drm_dp_remote_aux_init(&port->aux);
2253
2254	/*
2255	 * Make sure the memory allocation for our parent branch stays
2256	 * around until our own memory allocation is released
2257	 */
2258	drm_dp_mst_get_mstb_malloc(mstb);
2259
2260	return port;
2261}
2262
2263static int
2264drm_dp_mst_handle_link_address_port(struct drm_dp_mst_branch *mstb,
2265				    struct drm_device *dev,
2266				    struct drm_dp_link_addr_reply_port *port_msg)
2267{
2268	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
2269	struct drm_dp_mst_port *port;
2270	int old_ddps = 0, ret;
2271	u8 new_pdt = DP_PEER_DEVICE_NONE;
2272	bool new_mcs = 0;
2273	bool created = false, send_link_addr = false, changed = false;
2274
2275	port = drm_dp_get_port(mstb, port_msg->port_number);
2276	if (!port) {
2277		port = drm_dp_mst_add_port(dev, mgr, mstb,
2278					   port_msg->port_number);
2279		if (!port)
2280			return -ENOMEM;
2281		created = true;
2282		changed = true;
2283	} else if (!port->input && port_msg->input_port && port->connector) {
2284		/* Since port->connector can't be changed here, we create a
2285		 * new port if input_port changes from 0 to 1
2286		 */
2287		drm_dp_mst_topology_unlink_port(mgr, port);
2288		drm_dp_mst_topology_put_port(port);
2289		port = drm_dp_mst_add_port(dev, mgr, mstb,
2290					   port_msg->port_number);
2291		if (!port)
2292			return -ENOMEM;
2293		changed = true;
2294		created = true;
2295	} else if (port->input && !port_msg->input_port) {
2296		changed = true;
2297	} else if (port->connector) {
2298		/* We're updating a port that's exposed to userspace, so do it
2299		 * under lock
2300		 */
2301		drm_modeset_lock(&mgr->base.lock, NULL);
2302
2303		old_ddps = port->ddps;
2304		changed = port->ddps != port_msg->ddps ||
2305			(port->ddps &&
2306			 (port->ldps != port_msg->legacy_device_plug_status ||
2307			  port->dpcd_rev != port_msg->dpcd_revision ||
2308			  port->mcs != port_msg->mcs ||
2309			  port->pdt != port_msg->peer_device_type ||
2310			  port->num_sdp_stream_sinks !=
2311			  port_msg->num_sdp_stream_sinks));
2312	}
2313
2314	port->input = port_msg->input_port;
2315	if (!port->input)
2316		new_pdt = port_msg->peer_device_type;
2317	new_mcs = port_msg->mcs;
2318	port->ddps = port_msg->ddps;
2319	port->ldps = port_msg->legacy_device_plug_status;
2320	port->dpcd_rev = port_msg->dpcd_revision;
2321	port->num_sdp_streams = port_msg->num_sdp_streams;
2322	port->num_sdp_stream_sinks = port_msg->num_sdp_stream_sinks;
2323
2324	/* manage mstb port lists with mgr lock - take a reference
2325	   for this list */
2326	if (created) {
2327		mutex_lock(&mgr->lock);
2328		drm_dp_mst_topology_get_port(port);
2329		list_add(&port->next, &mstb->ports);
2330		mstb->num_ports++;
2331		mutex_unlock(&mgr->lock);
2332	}
2333
2334	/*
2335	 * Reprobe PBN caps on both hotplug, and when re-probing the link
2336	 * for our parent mstb
2337	 */
2338	if (old_ddps != port->ddps || !created) {
2339		if (port->ddps && !port->input) {
2340			ret = drm_dp_send_enum_path_resources(mgr, mstb,
2341							      port);
2342			if (ret == 1)
2343				changed = true;
2344		} else {
2345			port->full_pbn = 0;
2346		}
2347	}
2348
2349	ret = drm_dp_port_set_pdt(port, new_pdt, new_mcs);
2350	if (ret == 1) {
2351		send_link_addr = true;
2352	} else if (ret < 0) {
2353		DRM_ERROR("Failed to change PDT on port %p: %d\n",
2354			  port, ret);
2355		goto fail;
2356	}
2357
2358	/*
2359	 * If this port wasn't just created, then we're reprobing because
2360	 * we're coming out of suspend. In this case, always resend the link
2361	 * address if there's an MSTB on this port
2362	 */
2363	if (!created && port->pdt == DP_PEER_DEVICE_MST_BRANCHING &&
2364	    port->mcs)
2365		send_link_addr = true;
2366
2367	if (port->connector)
2368		drm_modeset_unlock(&mgr->base.lock);
2369	else if (!port->input)
2370		drm_dp_mst_port_add_connector(mstb, port);
2371
2372	if (send_link_addr && port->mstb) {
2373		ret = drm_dp_send_link_address(mgr, port->mstb);
2374		if (ret == 1) /* MSTB below us changed */
2375			changed = true;
2376		else if (ret < 0)
2377			goto fail_put;
2378	}
2379
2380	/* put reference to this port */
2381	drm_dp_mst_topology_put_port(port);
2382	return changed;
2383
2384fail:
2385	drm_dp_mst_topology_unlink_port(mgr, port);
2386	if (port->connector)
2387		drm_modeset_unlock(&mgr->base.lock);
2388fail_put:
2389	drm_dp_mst_topology_put_port(port);
2390	return ret;
2391}
2392
2393static void
2394drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch *mstb,
2395			    struct drm_dp_connection_status_notify *conn_stat)
2396{
2397	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
2398	struct drm_dp_mst_port *port;
2399	int old_ddps, old_input, ret, i;
2400	u8 new_pdt;
2401	bool new_mcs;
2402	bool dowork = false, create_connector = false;
2403
2404	port = drm_dp_get_port(mstb, conn_stat->port_number);
2405	if (!port)
2406		return;
2407
2408	if (port->connector) {
2409		if (!port->input && conn_stat->input_port) {
2410			/*
2411			 * We can't remove a connector from an already exposed
2412			 * port, so just throw the port out and make sure we
2413			 * reprobe the link address of it's parent MSTB
2414			 */
2415			drm_dp_mst_topology_unlink_port(mgr, port);
2416			mstb->link_address_sent = false;
2417			dowork = true;
2418			goto out;
2419		}
2420
2421		/* Locking is only needed if the port's exposed to userspace */
2422		drm_modeset_lock(&mgr->base.lock, NULL);
2423	} else if (port->input && !conn_stat->input_port) {
2424		create_connector = true;
2425		/* Reprobe link address so we get num_sdp_streams */
2426		mstb->link_address_sent = false;
2427		dowork = true;
2428	}
2429
2430	old_ddps = port->ddps;
2431	old_input = port->input;
2432	port->input = conn_stat->input_port;
2433	port->ldps = conn_stat->legacy_device_plug_status;
2434	port->ddps = conn_stat->displayport_device_plug_status;
2435
2436	if (old_ddps != port->ddps) {
2437		if (port->ddps && !port->input)
2438			drm_dp_send_enum_path_resources(mgr, mstb, port);
2439		else
2440			port->full_pbn = 0;
2441	}
2442
2443	new_pdt = port->input ? DP_PEER_DEVICE_NONE : conn_stat->peer_device_type;
2444	new_mcs = conn_stat->message_capability_status;
2445	ret = drm_dp_port_set_pdt(port, new_pdt, new_mcs);
2446	if (ret == 1) {
2447		dowork = true;
2448	} else if (ret < 0) {
2449		DRM_ERROR("Failed to change PDT for port %p: %d\n",
2450			  port, ret);
2451		dowork = false;
2452	}
2453
2454	if (!old_input && old_ddps != port->ddps && !port->ddps) {
2455		for (i = 0; i < mgr->max_payloads; i++) {
2456			struct drm_dp_vcpi *vcpi = mgr->proposed_vcpis[i];
2457			struct drm_dp_mst_port *port_validated;
2458
2459			if (!vcpi)
2460				continue;
2461
2462			port_validated =
2463				container_of(vcpi, struct drm_dp_mst_port, vcpi);
2464			port_validated =
2465				drm_dp_mst_topology_get_port_validated(mgr, port_validated);
2466			if (!port_validated) {
2467				mutex_lock(&mgr->payload_lock);
2468				vcpi->num_slots = 0;
2469				mutex_unlock(&mgr->payload_lock);
2470			} else {
2471				drm_dp_mst_topology_put_port(port_validated);
2472			}
2473		}
2474	}
2475
2476	if (port->connector)
2477		drm_modeset_unlock(&mgr->base.lock);
2478	else if (create_connector)
2479		drm_dp_mst_port_add_connector(mstb, port);
2480
2481out:
2482	drm_dp_mst_topology_put_port(port);
2483	if (dowork)
2484		queue_work(system_long_wq, &mstb->mgr->work);
2485}
2486
2487static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_topology_mgr *mgr,
2488							       u8 lct, u8 *rad)
2489{
2490	struct drm_dp_mst_branch *mstb;
2491	struct drm_dp_mst_port *port;
2492	int i, ret;
2493	/* find the port by iterating down */
2494
2495	mutex_lock(&mgr->lock);
2496	mstb = mgr->mst_primary;
2497
2498	if (!mstb)
2499		goto out;
2500
2501	for (i = 0; i < lct - 1; i++) {
2502		int shift = (i % 2) ? 0 : 4;
2503		int port_num = (rad[i / 2] >> shift) & 0xf;
2504
2505		list_for_each_entry(port, &mstb->ports, next) {
2506			if (port->port_num == port_num) {
2507				mstb = port->mstb;
2508				if (!mstb) {
2509					DRM_ERROR("failed to lookup MSTB with lct %d, rad %02x\n", lct, rad[0]);
2510					goto out;
2511				}
2512
2513				break;
2514			}
2515		}
2516	}
2517	ret = drm_dp_mst_topology_try_get_mstb(mstb);
2518	if (!ret)
2519		mstb = NULL;
2520out:
2521	mutex_unlock(&mgr->lock);
2522	return mstb;
2523}
2524
2525static struct drm_dp_mst_branch *get_mst_branch_device_by_guid_helper(
2526	struct drm_dp_mst_branch *mstb,
2527	const uint8_t *guid)
2528{
2529	struct drm_dp_mst_branch *found_mstb;
2530	struct drm_dp_mst_port *port;
2531
2532	if (memcmp(mstb->guid, guid, 16) == 0)
2533		return mstb;
2534
2535
2536	list_for_each_entry(port, &mstb->ports, next) {
2537		if (!port->mstb)
2538			continue;
2539
2540		found_mstb = get_mst_branch_device_by_guid_helper(port->mstb, guid);
2541
2542		if (found_mstb)
2543			return found_mstb;
2544	}
2545
2546	return NULL;
2547}
2548
2549static struct drm_dp_mst_branch *
2550drm_dp_get_mst_branch_device_by_guid(struct drm_dp_mst_topology_mgr *mgr,
2551				     const uint8_t *guid)
2552{
2553	struct drm_dp_mst_branch *mstb;
2554	int ret;
2555
2556	/* find the port by iterating down */
2557	mutex_lock(&mgr->lock);
2558
2559	mstb = get_mst_branch_device_by_guid_helper(mgr->mst_primary, guid);
2560	if (mstb) {
2561		ret = drm_dp_mst_topology_try_get_mstb(mstb);
2562		if (!ret)
2563			mstb = NULL;
2564	}
2565
2566	mutex_unlock(&mgr->lock);
2567	return mstb;
2568}
2569
2570static int drm_dp_check_and_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
2571					       struct drm_dp_mst_branch *mstb)
2572{
2573	struct drm_dp_mst_port *port;
2574	int ret;
2575	bool changed = false;
2576
2577	if (!mstb->link_address_sent) {
2578		ret = drm_dp_send_link_address(mgr, mstb);
2579		if (ret == 1)
2580			changed = true;
2581		else if (ret < 0)
2582			return ret;
2583	}
2584
2585	list_for_each_entry(port, &mstb->ports, next) {
2586		struct drm_dp_mst_branch *mstb_child = NULL;
2587
2588		if (port->input || !port->ddps)
2589			continue;
2590
2591		if (port->mstb)
2592			mstb_child = drm_dp_mst_topology_get_mstb_validated(
2593			    mgr, port->mstb);
2594
2595		if (mstb_child) {
2596			ret = drm_dp_check_and_send_link_address(mgr,
2597								 mstb_child);
2598			drm_dp_mst_topology_put_mstb(mstb_child);
2599			if (ret == 1)
2600				changed = true;
2601			else if (ret < 0)
2602				return ret;
2603		}
2604	}
2605
2606	return changed;
2607}
2608
2609static void drm_dp_mst_link_probe_work(struct work_struct *work)
2610{
2611	struct drm_dp_mst_topology_mgr *mgr =
2612		container_of(work, struct drm_dp_mst_topology_mgr, work);
2613	struct drm_device *dev = mgr->dev;
2614	struct drm_dp_mst_branch *mstb;
2615	int ret;
2616	bool clear_payload_id_table;
2617
2618	mutex_lock(&mgr->probe_lock);
2619
2620	mutex_lock(&mgr->lock);
2621	clear_payload_id_table = !mgr->payload_id_table_cleared;
2622	mgr->payload_id_table_cleared = true;
2623
2624	mstb = mgr->mst_primary;
2625	if (mstb) {
2626		ret = drm_dp_mst_topology_try_get_mstb(mstb);
2627		if (!ret)
2628			mstb = NULL;
2629	}
2630	mutex_unlock(&mgr->lock);
2631	if (!mstb) {
2632		mutex_unlock(&mgr->probe_lock);
2633		return;
2634	}
2635
2636	/*
2637	 * Certain branch devices seem to incorrectly report an available_pbn
2638	 * of 0 on downstream sinks, even after clearing the
2639	 * DP_PAYLOAD_ALLOCATE_* registers in
2640	 * drm_dp_mst_topology_mgr_set_mst(). Namely, the CableMatters USB-C
2641	 * 2x DP hub. Sending a CLEAR_PAYLOAD_ID_TABLE message seems to make
2642	 * things work again.
2643	 */
2644	if (clear_payload_id_table) {
2645		DRM_DEBUG_KMS("Clearing payload ID table\n");
2646		drm_dp_send_clear_payload_id_table(mgr, mstb);
2647	}
2648
2649	ret = drm_dp_check_and_send_link_address(mgr, mstb);
2650	drm_dp_mst_topology_put_mstb(mstb);
2651
2652	mutex_unlock(&mgr->probe_lock);
2653	if (ret)
2654		drm_kms_helper_hotplug_event(dev);
2655}
2656
2657static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
2658				 u8 *guid)
2659{
2660	u64 salt;
2661
2662	if (memchr_inv(guid, 0, 16))
2663		return true;
2664
2665	salt = get_jiffies_64();
2666
2667	memcpy(&guid[0], &salt, sizeof(u64));
2668	memcpy(&guid[8], &salt, sizeof(u64));
2669
2670	return false;
2671}
2672
2673static void build_dpcd_read(struct drm_dp_sideband_msg_tx *msg,
2674			    u8 port_num, u32 offset, u8 num_bytes)
2675{
2676	struct drm_dp_sideband_msg_req_body req;
2677
2678	req.req_type = DP_REMOTE_DPCD_READ;
2679	req.u.dpcd_read.port_number = port_num;
2680	req.u.dpcd_read.dpcd_address = offset;
2681	req.u.dpcd_read.num_bytes = num_bytes;
2682	drm_dp_encode_sideband_req(&req, msg);
2683}
2684
2685static int drm_dp_send_sideband_msg(struct drm_dp_mst_topology_mgr *mgr,
2686				    bool up, u8 *msg, int len)
2687{
2688	int ret;
2689	int regbase = up ? DP_SIDEBAND_MSG_UP_REP_BASE : DP_SIDEBAND_MSG_DOWN_REQ_BASE;
2690	int tosend, total, offset;
2691	int retries = 0;
2692
2693retry:
2694	total = len;
2695	offset = 0;
2696	do {
2697		tosend = min3(mgr->max_dpcd_transaction_bytes, 16, total);
2698
2699		ret = drm_dp_dpcd_write(mgr->aux, regbase + offset,
2700					&msg[offset],
2701					tosend);
2702		if (ret != tosend) {
2703			if (ret == -EIO && retries < 5) {
2704				retries++;
2705				goto retry;
2706			}
2707			DRM_DEBUG_KMS("failed to dpcd write %d %d\n", tosend, ret);
2708
2709			return -EIO;
2710		}
2711		offset += tosend;
2712		total -= tosend;
2713	} while (total > 0);
2714	return 0;
2715}
2716
2717static int set_hdr_from_dst_qlock(struct drm_dp_sideband_msg_hdr *hdr,
2718				  struct drm_dp_sideband_msg_tx *txmsg)
2719{
2720	struct drm_dp_mst_branch *mstb = txmsg->dst;
2721	u8 req_type;
2722
2723	req_type = txmsg->msg[0] & 0x7f;
2724	if (req_type == DP_CONNECTION_STATUS_NOTIFY ||
2725		req_type == DP_RESOURCE_STATUS_NOTIFY)
2726		hdr->broadcast = 1;
2727	else
2728		hdr->broadcast = 0;
2729	hdr->path_msg = txmsg->path_msg;
2730	hdr->lct = mstb->lct;
2731	hdr->lcr = mstb->lct - 1;
2732	if (mstb->lct > 1)
2733		memcpy(hdr->rad, mstb->rad, mstb->lct / 2);
2734
2735	return 0;
2736}
2737/*
2738 * process a single block of the next message in the sideband queue
2739 */
2740static int process_single_tx_qlock(struct drm_dp_mst_topology_mgr *mgr,
2741				   struct drm_dp_sideband_msg_tx *txmsg,
2742				   bool up)
2743{
2744	u8 chunk[48];
2745	struct drm_dp_sideband_msg_hdr hdr;
2746	int len, space, idx, tosend;
2747	int ret;
2748
2749	if (txmsg->state == DRM_DP_SIDEBAND_TX_SENT)
2750		return 0;
2751
2752	memset(&hdr, 0, sizeof(struct drm_dp_sideband_msg_hdr));
2753
2754	if (txmsg->state == DRM_DP_SIDEBAND_TX_QUEUED)
2755		txmsg->state = DRM_DP_SIDEBAND_TX_START_SEND;
2756
2757	/* make hdr from dst mst */
2758	ret = set_hdr_from_dst_qlock(&hdr, txmsg);
2759	if (ret < 0)
2760		return ret;
2761
2762	/* amount left to send in this message */
2763	len = txmsg->cur_len - txmsg->cur_offset;
2764
2765	/* 48 - sideband msg size - 1 byte for data CRC, x header bytes */
2766	space = 48 - 1 - drm_dp_calc_sb_hdr_size(&hdr);
2767
2768	tosend = min(len, space);
2769	if (len == txmsg->cur_len)
2770		hdr.somt = 1;
2771	if (space >= len)
2772		hdr.eomt = 1;
2773
2774
2775	hdr.msg_len = tosend + 1;
2776	drm_dp_encode_sideband_msg_hdr(&hdr, chunk, &idx);
2777	memcpy(&chunk[idx], &txmsg->msg[txmsg->cur_offset], tosend);
2778	/* add crc at end */
2779	drm_dp_crc_sideband_chunk_req(&chunk[idx], tosend);
2780	idx += tosend + 1;
2781
2782	ret = drm_dp_send_sideband_msg(mgr, up, chunk, idx);
2783	if (unlikely(ret) && drm_debug_enabled(DRM_UT_DP)) {
2784		struct drm_printer p = drm_debug_printer(DBG_PREFIX);
2785
2786		drm_printf(&p, "sideband msg failed to send\n");
2787		drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
2788		return ret;
2789	}
2790
2791	txmsg->cur_offset += tosend;
2792	if (txmsg->cur_offset == txmsg->cur_len) {
2793		txmsg->state = DRM_DP_SIDEBAND_TX_SENT;
2794		return 1;
2795	}
2796	return 0;
2797}
2798
2799static void process_single_down_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
2800{
2801	struct drm_dp_sideband_msg_tx *txmsg;
2802	int ret;
2803
2804	WARN_ON(!mutex_is_locked(&mgr->qlock));
2805
2806	/* construct a chunk from the first msg in the tx_msg queue */
2807	if (list_empty(&mgr->tx_msg_downq))
2808		return;
2809
2810	txmsg = list_first_entry(&mgr->tx_msg_downq,
2811				 struct drm_dp_sideband_msg_tx, next);
2812	ret = process_single_tx_qlock(mgr, txmsg, false);
2813	if (ret < 0) {
2814		DRM_DEBUG_KMS("failed to send msg in q %d\n", ret);
2815		list_del(&txmsg->next);
2816		txmsg->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
2817		wake_up_all(&mgr->tx_waitq);
2818	}
2819}
2820
2821static void drm_dp_queue_down_tx(struct drm_dp_mst_topology_mgr *mgr,
2822				 struct drm_dp_sideband_msg_tx *txmsg)
2823{
2824	mutex_lock(&mgr->qlock);
2825	list_add_tail(&txmsg->next, &mgr->tx_msg_downq);
2826
2827	if (drm_debug_enabled(DRM_UT_DP)) {
2828		struct drm_printer p = drm_debug_printer(DBG_PREFIX);
2829
2830		drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
2831	}
2832
2833	if (list_is_singular(&mgr->tx_msg_downq))
2834		process_single_down_tx_qlock(mgr);
2835	mutex_unlock(&mgr->qlock);
2836}
2837
2838static void
2839drm_dp_dump_link_address(struct drm_dp_link_address_ack_reply *reply)
2840{
2841	struct drm_dp_link_addr_reply_port *port_reply;
2842	int i;
2843
2844	for (i = 0; i < reply->nports; i++) {
2845		port_reply = &reply->ports[i];
2846		DRM_DEBUG_KMS("port %d: input %d, pdt: %d, pn: %d, dpcd_rev: %02x, mcs: %d, ddps: %d, ldps %d, sdp %d/%d\n",
2847			      i,
2848			      port_reply->input_port,
2849			      port_reply->peer_device_type,
2850			      port_reply->port_number,
2851			      port_reply->dpcd_revision,
2852			      port_reply->mcs,
2853			      port_reply->ddps,
2854			      port_reply->legacy_device_plug_status,
2855			      port_reply->num_sdp_streams,
2856			      port_reply->num_sdp_stream_sinks);
2857	}
2858}
2859
2860static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
2861				     struct drm_dp_mst_branch *mstb)
2862{
2863	struct drm_dp_sideband_msg_tx *txmsg;
2864	struct drm_dp_link_address_ack_reply *reply;
2865	struct drm_dp_mst_port *port, *tmp;
2866	int i, ret, port_mask = 0;
2867	bool changed = false;
2868
2869	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2870	if (!txmsg)
2871		return -ENOMEM;
2872
2873	txmsg->dst = mstb;
2874	build_link_address(txmsg);
2875
2876	mstb->link_address_sent = true;
2877	drm_dp_queue_down_tx(mgr, txmsg);
2878
2879	/* FIXME: Actually do some real error handling here */
2880	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
2881	if (ret <= 0) {
2882		DRM_ERROR("Sending link address failed with %d\n", ret);
2883		goto out;
2884	}
2885	if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
2886		DRM_ERROR("link address NAK received\n");
2887		ret = -EIO;
2888		goto out;
2889	}
2890
2891	reply = &txmsg->reply.u.link_addr;
2892	DRM_DEBUG_KMS("link address reply: %d\n", reply->nports);
2893	drm_dp_dump_link_address(reply);
2894
2895	ret = drm_dp_check_mstb_guid(mstb, reply->guid);
2896	if (ret) {
2897		char buf[64];
2898
2899		drm_dp_mst_rad_to_str(mstb->rad, mstb->lct, buf, sizeof(buf));
2900		DRM_ERROR("GUID check on %s failed: %d\n",
2901			  buf, ret);
2902		goto out;
2903	}
2904
2905	for (i = 0; i < reply->nports; i++) {
2906		port_mask |= BIT(reply->ports[i].port_number);
2907		ret = drm_dp_mst_handle_link_address_port(mstb, mgr->dev,
2908							  &reply->ports[i]);
2909		if (ret == 1)
2910			changed = true;
2911		else if (ret < 0)
2912			goto out;
2913	}
2914
2915	/* Prune any ports that are currently a part of mstb in our in-memory
2916	 * topology, but were not seen in this link address. Usually this
2917	 * means that they were removed while the topology was out of sync,
2918	 * e.g. during suspend/resume
2919	 */
2920	mutex_lock(&mgr->lock);
2921	list_for_each_entry_safe(port, tmp, &mstb->ports, next) {
2922		if (port_mask & BIT(port->port_num))
2923			continue;
2924
2925		DRM_DEBUG_KMS("port %d was not in link address, removing\n",
2926			      port->port_num);
2927		list_del(&port->next);
2928		drm_dp_mst_topology_put_port(port);
2929		changed = true;
2930	}
2931	mutex_unlock(&mgr->lock);
2932
2933out:
2934	if (ret <= 0)
2935		mstb->link_address_sent = false;
2936	kfree(txmsg);
2937	return ret < 0 ? ret : changed;
2938}
2939
2940static void
2941drm_dp_send_clear_payload_id_table(struct drm_dp_mst_topology_mgr *mgr,
2942				   struct drm_dp_mst_branch *mstb)
2943{
2944	struct drm_dp_sideband_msg_tx *txmsg;
2945	int ret;
2946
2947	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2948	if (!txmsg)
2949		return;
2950
2951	txmsg->dst = mstb;
2952	build_clear_payload_id_table(txmsg);
2953
2954	drm_dp_queue_down_tx(mgr, txmsg);
2955
2956	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
2957	if (ret > 0 && txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
2958		DRM_DEBUG_KMS("clear payload table id nak received\n");
2959
2960	kfree(txmsg);
2961}
2962
2963static int
2964drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
2965				struct drm_dp_mst_branch *mstb,
2966				struct drm_dp_mst_port *port)
2967{
2968	struct drm_dp_enum_path_resources_ack_reply *path_res;
2969	struct drm_dp_sideband_msg_tx *txmsg;
2970	int ret;
2971
2972	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2973	if (!txmsg)
2974		return -ENOMEM;
2975
2976	txmsg->dst = mstb;
2977	build_enum_path_resources(txmsg, port->port_num);
2978
2979	drm_dp_queue_down_tx(mgr, txmsg);
2980
2981	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
2982	if (ret > 0) {
2983		ret = 0;
2984		path_res = &txmsg->reply.u.path_resources;
2985
2986		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
2987			DRM_DEBUG_KMS("enum path resources nak received\n");
2988		} else {
2989			if (port->port_num != path_res->port_number)
2990				DRM_ERROR("got incorrect port in response\n");
2991
2992			DRM_DEBUG_KMS("enum path resources %d: %d %d\n",
2993				      path_res->port_number,
2994				      path_res->full_payload_bw_number,
2995				      path_res->avail_payload_bw_number);
2996
2997			/*
2998			 * If something changed, make sure we send a
2999			 * hotplug
3000			 */
3001			if (port->full_pbn != path_res->full_payload_bw_number ||
3002			    port->fec_capable != path_res->fec_capable)
3003				ret = 1;
3004
3005			port->full_pbn = path_res->full_payload_bw_number;
3006			port->fec_capable = path_res->fec_capable;
3007		}
3008	}
3009
3010	kfree(txmsg);
3011	return ret;
3012}
3013
3014static struct drm_dp_mst_port *drm_dp_get_last_connected_port_to_mstb(struct drm_dp_mst_branch *mstb)
3015{
3016	if (!mstb->port_parent)
3017		return NULL;
3018
3019	if (mstb->port_parent->mstb != mstb)
3020		return mstb->port_parent;
3021
3022	return drm_dp_get_last_connected_port_to_mstb(mstb->port_parent->parent);
3023}
3024
3025/*
3026 * Searches upwards in the topology starting from mstb to try to find the
3027 * closest available parent of mstb that's still connected to the rest of the
3028 * topology. This can be used in order to perform operations like releasing
3029 * payloads, where the branch device which owned the payload may no longer be
3030 * around and thus would require that the payload on the last living relative
3031 * be freed instead.
3032 */
3033static struct drm_dp_mst_branch *
3034drm_dp_get_last_connected_port_and_mstb(struct drm_dp_mst_topology_mgr *mgr,
3035					struct drm_dp_mst_branch *mstb,
3036					int *port_num)
3037{
3038	struct drm_dp_mst_branch *rmstb = NULL;
3039	struct drm_dp_mst_port *found_port;
3040
3041	mutex_lock(&mgr->lock);
3042	if (!mgr->mst_primary)
3043		goto out;
3044
3045	do {
3046		found_port = drm_dp_get_last_connected_port_to_mstb(mstb);
3047		if (!found_port)
3048			break;
3049
3050		if (drm_dp_mst_topology_try_get_mstb(found_port->parent)) {
3051			rmstb = found_port->parent;
3052			*port_num = found_port->port_num;
3053		} else {
3054			/* Search again, starting from this parent */
3055			mstb = found_port->parent;
3056		}
3057	} while (!rmstb);
3058out:
3059	mutex_unlock(&mgr->lock);
3060	return rmstb;
3061}
3062
3063static int drm_dp_payload_send_msg(struct drm_dp_mst_topology_mgr *mgr,
3064				   struct drm_dp_mst_port *port,
3065				   int id,
3066				   int pbn)
3067{
3068	struct drm_dp_sideband_msg_tx *txmsg;
3069	struct drm_dp_mst_branch *mstb;
3070	int ret, port_num;
3071	u8 sinks[DRM_DP_MAX_SDP_STREAMS];
3072	int i;
3073
3074	port_num = port->port_num;
3075	mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
3076	if (!mstb) {
3077		mstb = drm_dp_get_last_connected_port_and_mstb(mgr,
3078							       port->parent,
3079							       &port_num);
3080
3081		if (!mstb)
3082			return -EINVAL;
3083	}
3084
3085	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3086	if (!txmsg) {
3087		ret = -ENOMEM;
3088		goto fail_put;
3089	}
3090
3091	for (i = 0; i < port->num_sdp_streams; i++)
3092		sinks[i] = i;
3093
3094	txmsg->dst = mstb;
3095	build_allocate_payload(txmsg, port_num,
3096			       id,
3097			       pbn, port->num_sdp_streams, sinks);
3098
3099	drm_dp_queue_down_tx(mgr, txmsg);
3100
3101	/*
3102	 * FIXME: there is a small chance that between getting the last
3103	 * connected mstb and sending the payload message, the last connected
3104	 * mstb could also be removed from the topology. In the future, this
3105	 * needs to be fixed by restarting the
3106	 * drm_dp_get_last_connected_port_and_mstb() search in the event of a
3107	 * timeout if the topology is still connected to the system.
3108	 */
3109	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3110	if (ret > 0) {
3111		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
3112			ret = -EINVAL;
3113		else
3114			ret = 0;
3115	}
3116	kfree(txmsg);
3117fail_put:
3118	drm_dp_mst_topology_put_mstb(mstb);
3119	return ret;
3120}
3121
3122int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr,
3123				 struct drm_dp_mst_port *port, bool power_up)
3124{
3125	struct drm_dp_sideband_msg_tx *txmsg;
3126	int ret;
3127
3128	port = drm_dp_mst_topology_get_port_validated(mgr, port);
3129	if (!port)
3130		return -EINVAL;
3131
3132	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3133	if (!txmsg) {
3134		drm_dp_mst_topology_put_port(port);
3135		return -ENOMEM;
3136	}
3137
3138	txmsg->dst = port->parent;
3139	build_power_updown_phy(txmsg, port->port_num, power_up);
3140	drm_dp_queue_down_tx(mgr, txmsg);
3141
3142	ret = drm_dp_mst_wait_tx_reply(port->parent, txmsg);
3143	if (ret > 0) {
3144		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
3145			ret = -EINVAL;
3146		else
3147			ret = 0;
3148	}
3149	kfree(txmsg);
3150	drm_dp_mst_topology_put_port(port);
3151
3152	return ret;
3153}
3154EXPORT_SYMBOL(drm_dp_send_power_updown_phy);
3155
3156static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
3157				       int id,
3158				       struct drm_dp_payload *payload)
3159{
3160	int ret;
3161
3162	ret = drm_dp_dpcd_write_payload(mgr, id, payload);
3163	if (ret < 0) {
3164		payload->payload_state = 0;
3165		return ret;
3166	}
3167	payload->payload_state = DP_PAYLOAD_LOCAL;
3168	return 0;
3169}
3170
3171static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
3172				       struct drm_dp_mst_port *port,
3173				       int id,
3174				       struct drm_dp_payload *payload)
3175{
3176	int ret;
3177
3178	ret = drm_dp_payload_send_msg(mgr, port, id, port->vcpi.pbn);
3179	if (ret < 0)
3180		return ret;
3181	payload->payload_state = DP_PAYLOAD_REMOTE;
3182	return ret;
3183}
3184
3185static int drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
3186					struct drm_dp_mst_port *port,
3187					int id,
3188					struct drm_dp_payload *payload)
3189{
3190	DRM_DEBUG_KMS("\n");
3191	/* it's okay for these to fail */
3192	if (port) {
3193		drm_dp_payload_send_msg(mgr, port, id, 0);
3194	}
3195
3196	drm_dp_dpcd_write_payload(mgr, id, payload);
3197	payload->payload_state = DP_PAYLOAD_DELETE_LOCAL;
3198	return 0;
3199}
3200
3201static int drm_dp_destroy_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
3202					int id,
3203					struct drm_dp_payload *payload)
3204{
3205	payload->payload_state = 0;
3206	return 0;
3207}
3208
3209/**
3210 * drm_dp_update_payload_part1() - Execute payload update part 1
3211 * @mgr: manager to use.
3212 *
3213 * This iterates over all proposed virtual channels, and tries to
3214 * allocate space in the link for them. For 0->slots transitions,
3215 * this step just writes the VCPI to the MST device. For slots->0
3216 * transitions, this writes the updated VCPIs and removes the
3217 * remote VC payloads.
3218 *
3219 * after calling this the driver should generate ACT and payload
3220 * packets.
3221 */
3222int drm_dp_update_payload_part1(struct drm_dp_mst_topology_mgr *mgr)
3223{
3224	struct drm_dp_payload req_payload;
3225	struct drm_dp_mst_port *port;
3226	int i, j;
3227	int cur_slots = 1;
3228
3229	mutex_lock(&mgr->payload_lock);
3230	for (i = 0; i < mgr->max_payloads; i++) {
3231		struct drm_dp_vcpi *vcpi = mgr->proposed_vcpis[i];
3232		struct drm_dp_payload *payload = &mgr->payloads[i];
3233		bool put_port = false;
3234
3235		/* solve the current payloads - compare to the hw ones
3236		   - update the hw view */
3237		req_payload.start_slot = cur_slots;
3238		if (vcpi) {
3239			port = container_of(vcpi, struct drm_dp_mst_port,
3240					    vcpi);
3241
3242			/* Validated ports don't matter if we're releasing
3243			 * VCPI
3244			 */
3245			if (vcpi->num_slots) {
3246				port = drm_dp_mst_topology_get_port_validated(
3247				    mgr, port);
3248				if (!port) {
3249					mutex_unlock(&mgr->payload_lock);
3250					return -EINVAL;
3251				}
3252				put_port = true;
3253			}
3254
3255			req_payload.num_slots = vcpi->num_slots;
3256			req_payload.vcpi = vcpi->vcpi;
3257		} else {
3258			port = NULL;
3259			req_payload.num_slots = 0;
3260		}
3261
3262		payload->start_slot = req_payload.start_slot;
3263		/* work out what is required to happen with this payload */
3264		if (payload->num_slots != req_payload.num_slots) {
3265
3266			/* need to push an update for this payload */
3267			if (req_payload.num_slots) {
3268				drm_dp_create_payload_step1(mgr, vcpi->vcpi,
3269							    &req_payload);
3270				payload->num_slots = req_payload.num_slots;
3271				payload->vcpi = req_payload.vcpi;
3272
3273			} else if (payload->num_slots) {
3274				payload->num_slots = 0;
3275				drm_dp_destroy_payload_step1(mgr, port,
3276							     payload->vcpi,
3277							     payload);
3278				req_payload.payload_state =
3279					payload->payload_state;
3280				payload->start_slot = 0;
3281			}
3282			payload->payload_state = req_payload.payload_state;
3283		}
3284		cur_slots += req_payload.num_slots;
3285
3286		if (put_port)
3287			drm_dp_mst_topology_put_port(port);
3288	}
3289
3290	for (i = 0; i < mgr->max_payloads; /* do nothing */) {
3291		if (mgr->payloads[i].payload_state != DP_PAYLOAD_DELETE_LOCAL) {
3292			i++;
3293			continue;
3294		}
3295
3296		DRM_DEBUG_KMS("removing payload %d\n", i);
3297		for (j = i; j < mgr->max_payloads - 1; j++) {
3298			mgr->payloads[j] = mgr->payloads[j + 1];
3299			mgr->proposed_vcpis[j] = mgr->proposed_vcpis[j + 1];
3300
3301			if (mgr->proposed_vcpis[j] &&
3302			    mgr->proposed_vcpis[j]->num_slots) {
3303				set_bit(j + 1, &mgr->payload_mask);
3304			} else {
3305				clear_bit(j + 1, &mgr->payload_mask);
3306			}
3307		}
3308
3309		memset(&mgr->payloads[mgr->max_payloads - 1], 0,
3310		       sizeof(struct drm_dp_payload));
3311		mgr->proposed_vcpis[mgr->max_payloads - 1] = NULL;
3312		clear_bit(mgr->max_payloads, &mgr->payload_mask);
3313	}
3314	mutex_unlock(&mgr->payload_lock);
3315
3316	return 0;
3317}
3318EXPORT_SYMBOL(drm_dp_update_payload_part1);
3319
3320/**
3321 * drm_dp_update_payload_part2() - Execute payload update part 2
3322 * @mgr: manager to use.
3323 *
3324 * This iterates over all proposed virtual channels, and tries to
3325 * allocate space in the link for them. For 0->slots transitions,
3326 * this step writes the remote VC payload commands. For slots->0
3327 * this just resets some internal state.
3328 */
3329int drm_dp_update_payload_part2(struct drm_dp_mst_topology_mgr *mgr)
3330{
3331	struct drm_dp_mst_port *port;
3332	int i;
3333	int ret = 0;
3334
3335	mutex_lock(&mgr->payload_lock);
3336	for (i = 0; i < mgr->max_payloads; i++) {
3337
3338		if (!mgr->proposed_vcpis[i])
3339			continue;
3340
3341		port = container_of(mgr->proposed_vcpis[i], struct drm_dp_mst_port, vcpi);
3342
3343		DRM_DEBUG_KMS("payload %d %d\n", i, mgr->payloads[i].payload_state);
3344		if (mgr->payloads[i].payload_state == DP_PAYLOAD_LOCAL) {
3345			ret = drm_dp_create_payload_step2(mgr, port, mgr->proposed_vcpis[i]->vcpi, &mgr->payloads[i]);
3346		} else if (mgr->payloads[i].payload_state == DP_PAYLOAD_DELETE_LOCAL) {
3347			ret = drm_dp_destroy_payload_step2(mgr, mgr->proposed_vcpis[i]->vcpi, &mgr->payloads[i]);
3348		}
3349		if (ret) {
3350			mutex_unlock(&mgr->payload_lock);
3351			return ret;
3352		}
3353	}
3354	mutex_unlock(&mgr->payload_lock);
3355	return 0;
3356}
3357EXPORT_SYMBOL(drm_dp_update_payload_part2);
3358
3359static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
3360				 struct drm_dp_mst_port *port,
3361				 int offset, int size, u8 *bytes)
3362{
3363	int ret = 0;
3364	struct drm_dp_sideband_msg_tx *txmsg;
3365	struct drm_dp_mst_branch *mstb;
3366
3367	mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
3368	if (!mstb)
3369		return -EINVAL;
3370
3371	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3372	if (!txmsg) {
3373		ret = -ENOMEM;
3374		goto fail_put;
3375	}
3376
3377	build_dpcd_read(txmsg, port->port_num, offset, size);
3378	txmsg->dst = port->parent;
3379
3380	drm_dp_queue_down_tx(mgr, txmsg);
3381
3382	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3383	if (ret < 0)
3384		goto fail_free;
3385
3386	/* DPCD read should never be NACKed */
3387	if (txmsg->reply.reply_type == 1) {
3388		DRM_ERROR("mstb %p port %d: DPCD read on addr 0x%x for %d bytes NAKed\n",
3389			  mstb, port->port_num, offset, size);
3390		ret = -EIO;
3391		goto fail_free;
3392	}
3393
3394	if (txmsg->reply.u.remote_dpcd_read_ack.num_bytes != size) {
3395		ret = -EPROTO;
3396		goto fail_free;
3397	}
3398
3399	ret = min_t(size_t, txmsg->reply.u.remote_dpcd_read_ack.num_bytes,
3400		    size);
3401	memcpy(bytes, txmsg->reply.u.remote_dpcd_read_ack.bytes, ret);
3402
3403fail_free:
3404	kfree(txmsg);
3405fail_put:
3406	drm_dp_mst_topology_put_mstb(mstb);
3407
3408	return ret;
3409}
3410
3411static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
3412				  struct drm_dp_mst_port *port,
3413				  int offset, int size, u8 *bytes)
3414{
3415	int ret;
3416	struct drm_dp_sideband_msg_tx *txmsg;
3417	struct drm_dp_mst_branch *mstb;
3418
3419	mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
3420	if (!mstb)
3421		return -EINVAL;
3422
3423	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3424	if (!txmsg) {
3425		ret = -ENOMEM;
3426		goto fail_put;
3427	}
3428
3429	build_dpcd_write(txmsg, port->port_num, offset, size, bytes);
3430	txmsg->dst = mstb;
3431
3432	drm_dp_queue_down_tx(mgr, txmsg);
3433
3434	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3435	if (ret > 0) {
3436		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
3437			ret = -EIO;
3438		else
3439			ret = size;
3440	}
3441
3442	kfree(txmsg);
3443fail_put:
3444	drm_dp_mst_topology_put_mstb(mstb);
3445	return ret;
3446}
3447
3448static int drm_dp_encode_up_ack_reply(struct drm_dp_sideband_msg_tx *msg, u8 req_type)
3449{
3450	struct drm_dp_sideband_msg_reply_body reply;
3451
3452	reply.reply_type = DP_SIDEBAND_REPLY_ACK;
3453	reply.req_type = req_type;
3454	drm_dp_encode_sideband_reply(&reply, msg);
3455	return 0;
3456}
3457
3458static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr,
3459				    struct drm_dp_mst_branch *mstb,
3460				    int req_type, bool broadcast)
3461{
3462	struct drm_dp_sideband_msg_tx *txmsg;
3463
3464	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3465	if (!txmsg)
3466		return -ENOMEM;
3467
3468	txmsg->dst = mstb;
3469	drm_dp_encode_up_ack_reply(txmsg, req_type);
3470
3471	mutex_lock(&mgr->qlock);
3472	/* construct a chunk from the first msg in the tx_msg queue */
3473	process_single_tx_qlock(mgr, txmsg, true);
3474	mutex_unlock(&mgr->qlock);
3475
3476	kfree(txmsg);
3477	return 0;
3478}
3479
3480static int drm_dp_get_vc_payload_bw(u8 dp_link_bw, u8  dp_link_count)
3481{
3482	if (dp_link_bw == 0 || dp_link_count == 0)
3483		DRM_DEBUG_KMS("invalid link bandwidth in DPCD: %x (link count: %d)\n",
3484			      dp_link_bw, dp_link_count);
3485
3486	return dp_link_bw * dp_link_count / 2;
3487}
3488
3489/**
3490 * drm_dp_mst_topology_mgr_set_mst() - Set the MST state for a topology manager
3491 * @mgr: manager to set state for
3492 * @mst_state: true to enable MST on this connector - false to disable.
3493 *
3494 * This is called by the driver when it detects an MST capable device plugged
3495 * into a DP MST capable port, or when a DP MST capable device is unplugged.
3496 */
3497int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state)
3498{
3499	int ret = 0;
3500	struct drm_dp_mst_branch *mstb = NULL;
3501
3502	mutex_lock(&mgr->payload_lock);
3503	mutex_lock(&mgr->lock);
3504	if (mst_state == mgr->mst_state)
3505		goto out_unlock;
3506
3507	mgr->mst_state = mst_state;
3508	/* set the device into MST mode */
3509	if (mst_state) {
3510		struct drm_dp_payload reset_pay;
3511
3512		WARN_ON(mgr->mst_primary);
3513
3514		/* get dpcd info */
3515		ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd, DP_RECEIVER_CAP_SIZE);
3516		if (ret != DP_RECEIVER_CAP_SIZE) {
3517			DRM_DEBUG_KMS("failed to read DPCD\n");
3518			goto out_unlock;
3519		}
3520
3521		mgr->pbn_div = drm_dp_get_vc_payload_bw(mgr->dpcd[1],
3522							mgr->dpcd[2] & DP_MAX_LANE_COUNT_MASK);
3523		if (mgr->pbn_div == 0) {
3524			ret = -EINVAL;
3525			goto out_unlock;
3526		}
3527
3528		/* add initial branch device at LCT 1 */
3529		mstb = drm_dp_add_mst_branch_device(1, NULL);
3530		if (mstb == NULL) {
3531			ret = -ENOMEM;
3532			goto out_unlock;
3533		}
3534		mstb->mgr = mgr;
3535
3536		/* give this the main reference */
3537		mgr->mst_primary = mstb;
3538		drm_dp_mst_topology_get_mstb(mgr->mst_primary);
3539
3540		ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
3541					 DP_MST_EN |
3542					 DP_UP_REQ_EN |
3543					 DP_UPSTREAM_IS_SRC);
3544		if (ret < 0)
3545			goto out_unlock;
3546
3547		reset_pay.start_slot = 0;
3548		reset_pay.num_slots = 0x3f;
3549		drm_dp_dpcd_write_payload(mgr, 0, &reset_pay);
3550
3551		queue_work(system_long_wq, &mgr->work);
3552
3553		ret = 0;
3554	} else {
3555		/* disable MST on the device */
3556		mstb = mgr->mst_primary;
3557		mgr->mst_primary = NULL;
3558		/* this can fail if the device is gone */
3559		drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0);
3560		ret = 0;
3561		memset(mgr->payloads, 0,
3562		       mgr->max_payloads * sizeof(mgr->payloads[0]));
3563		memset(mgr->proposed_vcpis, 0,
3564		       mgr->max_payloads * sizeof(mgr->proposed_vcpis[0]));
3565		mgr->payload_mask = 0;
3566		set_bit(0, &mgr->payload_mask);
3567		mgr->vcpi_mask = 0;
3568		mgr->payload_id_table_cleared = false;
3569	}
3570
3571out_unlock:
3572	mutex_unlock(&mgr->lock);
3573	mutex_unlock(&mgr->payload_lock);
3574	if (mstb)
3575		drm_dp_mst_topology_put_mstb(mstb);
3576	return ret;
3577
3578}
3579EXPORT_SYMBOL(drm_dp_mst_topology_mgr_set_mst);
3580
3581static void
3582drm_dp_mst_topology_mgr_invalidate_mstb(struct drm_dp_mst_branch *mstb)
3583{
3584	struct drm_dp_mst_port *port;
3585
3586	/* The link address will need to be re-sent on resume */
3587	mstb->link_address_sent = false;
3588
3589	list_for_each_entry(port, &mstb->ports, next)
3590		if (port->mstb)
3591			drm_dp_mst_topology_mgr_invalidate_mstb(port->mstb);
3592}
3593
3594/**
3595 * drm_dp_mst_topology_mgr_suspend() - suspend the MST manager
3596 * @mgr: manager to suspend
3597 *
3598 * This function tells the MST device that we can't handle UP messages
3599 * anymore. This should stop it from sending any since we are suspended.
3600 */
3601void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr)
3602{
3603	mutex_lock(&mgr->lock);
3604	drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
3605			   DP_MST_EN | DP_UPSTREAM_IS_SRC);
3606	mutex_unlock(&mgr->lock);
3607	flush_work(&mgr->up_req_work);
3608	flush_work(&mgr->work);
3609	flush_work(&mgr->delayed_destroy_work);
3610
3611	mutex_lock(&mgr->lock);
3612	if (mgr->mst_state && mgr->mst_primary)
3613		drm_dp_mst_topology_mgr_invalidate_mstb(mgr->mst_primary);
3614	mutex_unlock(&mgr->lock);
3615}
3616EXPORT_SYMBOL(drm_dp_mst_topology_mgr_suspend);
3617
3618/**
3619 * drm_dp_mst_topology_mgr_resume() - resume the MST manager
3620 * @mgr: manager to resume
3621 * @sync: whether or not to perform topology reprobing synchronously
3622 *
3623 * This will fetch DPCD and see if the device is still there,
3624 * if it is, it will rewrite the MSTM control bits, and return.
3625 *
3626 * If the device fails this returns -1, and the driver should do
3627 * a full MST reprobe, in case we were undocked.
3628 *
3629 * During system resume (where it is assumed that the driver will be calling
3630 * drm_atomic_helper_resume()) this function should be called beforehand with
3631 * @sync set to true. In contexts like runtime resume where the driver is not
3632 * expected to be calling drm_atomic_helper_resume(), this function should be
3633 * called with @sync set to false in order to avoid deadlocking.
3634 *
3635 * Returns: -1 if the MST topology was removed while we were suspended, 0
3636 * otherwise.
3637 */
3638int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr,
3639				   bool sync)
3640{
3641	int ret;
3642	u8 guid[16];
3643
3644	mutex_lock(&mgr->lock);
3645	if (!mgr->mst_primary)
3646		goto out_fail;
3647
3648	ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd,
3649			       DP_RECEIVER_CAP_SIZE);
3650	if (ret != DP_RECEIVER_CAP_SIZE) {
3651		DRM_DEBUG_KMS("dpcd read failed - undocked during suspend?\n");
3652		goto out_fail;
3653	}
3654
3655	ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
3656				 DP_MST_EN |
3657				 DP_UP_REQ_EN |
3658				 DP_UPSTREAM_IS_SRC);
3659	if (ret < 0) {
3660		DRM_DEBUG_KMS("mst write failed - undocked during suspend?\n");
3661		goto out_fail;
3662	}
3663
3664	/* Some hubs forget their guids after they resume */
3665	ret = drm_dp_dpcd_read(mgr->aux, DP_GUID, guid, 16);
3666	if (ret != 16) {
3667		DRM_DEBUG_KMS("dpcd read failed - undocked during suspend?\n");
3668		goto out_fail;
3669	}
3670
3671	ret = drm_dp_check_mstb_guid(mgr->mst_primary, guid);
3672	if (ret) {
3673		DRM_DEBUG_KMS("check mstb failed - undocked during suspend?\n");
3674		goto out_fail;
3675	}
3676
3677	/*
3678	 * For the final step of resuming the topology, we need to bring the
3679	 * state of our in-memory topology back into sync with reality. So,
3680	 * restart the probing process as if we're probing a new hub
3681	 */
3682	queue_work(system_long_wq, &mgr->work);
3683	mutex_unlock(&mgr->lock);
3684
3685	if (sync) {
3686		DRM_DEBUG_KMS("Waiting for link probe work to finish re-syncing topology...\n");
3687		flush_work(&mgr->work);
3688	}
3689
3690	return 0;
3691
3692out_fail:
3693	mutex_unlock(&mgr->lock);
3694	return -1;
3695}
3696EXPORT_SYMBOL(drm_dp_mst_topology_mgr_resume);
3697
3698static bool
3699drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up,
3700		      struct drm_dp_mst_branch **mstb)
3701{
3702	int len;
3703	u8 replyblock[32];
3704	int replylen, curreply;
3705	int ret;
3706	u8 hdrlen;
3707	struct drm_dp_sideband_msg_hdr hdr;
3708	struct drm_dp_sideband_msg_rx *msg =
3709		up ? &mgr->up_req_recv : &mgr->down_rep_recv;
3710	int basereg = up ? DP_SIDEBAND_MSG_UP_REQ_BASE :
3711			   DP_SIDEBAND_MSG_DOWN_REP_BASE;
3712
3713	if (!up)
3714		*mstb = NULL;
3715
3716	len = min(mgr->max_dpcd_transaction_bytes, 16);
3717	ret = drm_dp_dpcd_read(mgr->aux, basereg, replyblock, len);
3718	if (ret != len) {
3719		DRM_DEBUG_KMS("failed to read DPCD down rep %d %d\n", len, ret);
3720		return false;
3721	}
3722
3723	ret = drm_dp_decode_sideband_msg_hdr(&hdr, replyblock, len, &hdrlen);
3724	if (ret == false) {
3725		print_hex_dump(KERN_DEBUG, "failed hdr", DUMP_PREFIX_NONE, 16,
3726			       1, replyblock, len, false);
3727		DRM_DEBUG_KMS("ERROR: failed header\n");
3728		return false;
3729	}
3730
3731	if (!up) {
3732		/* Caller is responsible for giving back this reference */
3733		*mstb = drm_dp_get_mst_branch_device(mgr, hdr.lct, hdr.rad);
3734		if (!*mstb) {
3735			DRM_DEBUG_KMS("Got MST reply from unknown device %d\n",
3736				      hdr.lct);
3737			return false;
3738		}
3739	}
3740
3741	if (!drm_dp_sideband_msg_set_header(msg, &hdr, hdrlen)) {
3742		DRM_DEBUG_KMS("sideband msg set header failed %d\n",
3743			      replyblock[0]);
3744		return false;
3745	}
3746
3747	replylen = min(msg->curchunk_len, (u8)(len - hdrlen));
3748	ret = drm_dp_sideband_append_payload(msg, replyblock + hdrlen, replylen);
3749	if (!ret) {
3750		DRM_DEBUG_KMS("sideband msg build failed %d\n", replyblock[0]);
3751		return false;
3752	}
3753
3754	replylen = msg->curchunk_len + msg->curchunk_hdrlen - len;
3755	curreply = len;
3756	while (replylen > 0) {
3757		len = min3(replylen, mgr->max_dpcd_transaction_bytes, 16);
3758		ret = drm_dp_dpcd_read(mgr->aux, basereg + curreply,
3759				    replyblock, len);
3760		if (ret != len) {
3761			DRM_DEBUG_KMS("failed to read a chunk (len %d, ret %d)\n",
3762				      len, ret);
3763			return false;
3764		}
3765
3766		ret = drm_dp_sideband_append_payload(msg, replyblock, len);
3767		if (!ret) {
3768			DRM_DEBUG_KMS("failed to build sideband msg\n");
3769			return false;
3770		}
3771
3772		curreply += len;
3773		replylen -= len;
3774	}
3775	return true;
3776}
3777
3778static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr)
3779{
3780	struct drm_dp_sideband_msg_tx *txmsg;
3781	struct drm_dp_mst_branch *mstb = NULL;
3782	struct drm_dp_sideband_msg_rx *msg = &mgr->down_rep_recv;
3783
3784	if (!drm_dp_get_one_sb_msg(mgr, false, &mstb))
3785		goto out;
3786
3787	/* Multi-packet message transmission, don't clear the reply */
3788	if (!msg->have_eomt)
3789		goto out;
3790
3791	/* find the message */
3792	mutex_lock(&mgr->qlock);
3793	txmsg = list_first_entry_or_null(&mgr->tx_msg_downq,
3794					 struct drm_dp_sideband_msg_tx, next);
3795	mutex_unlock(&mgr->qlock);
3796
3797	/* Were we actually expecting a response, and from this mstb? */
3798	if (!txmsg || txmsg->dst != mstb) {
3799		struct drm_dp_sideband_msg_hdr *hdr;
3800
3801		hdr = &msg->initial_hdr;
3802		DRM_DEBUG_KMS("Got MST reply with no msg %p %d %d %02x %02x\n",
3803			      mstb, hdr->seqno, hdr->lct, hdr->rad[0],
3804			      msg->msg[0]);
3805		goto out_clear_reply;
3806	}
3807
3808	drm_dp_sideband_parse_reply(msg, &txmsg->reply);
3809
3810	if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
3811		DRM_DEBUG_KMS("Got NAK reply: req 0x%02x (%s), reason 0x%02x (%s), nak data 0x%02x\n",
3812			      txmsg->reply.req_type,
3813			      drm_dp_mst_req_type_str(txmsg->reply.req_type),
3814			      txmsg->reply.u.nak.reason,
3815			      drm_dp_mst_nak_reason_str(txmsg->reply.u.nak.reason),
3816			      txmsg->reply.u.nak.nak_data);
3817	}
3818
3819	memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
3820	drm_dp_mst_topology_put_mstb(mstb);
3821
3822	mutex_lock(&mgr->qlock);
3823	txmsg->state = DRM_DP_SIDEBAND_TX_RX;
3824	list_del(&txmsg->next);
3825	mutex_unlock(&mgr->qlock);
3826
3827	wake_up_all(&mgr->tx_waitq);
3828
3829	return 0;
3830
3831out_clear_reply:
3832	memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
3833out:
3834	if (mstb)
3835		drm_dp_mst_topology_put_mstb(mstb);
3836
3837	return 0;
3838}
3839
3840static inline bool
3841drm_dp_mst_process_up_req(struct drm_dp_mst_topology_mgr *mgr,
3842			  struct drm_dp_pending_up_req *up_req)
3843{
3844	struct drm_dp_mst_branch *mstb = NULL;
3845	struct drm_dp_sideband_msg_req_body *msg = &up_req->msg;
3846	struct drm_dp_sideband_msg_hdr *hdr = &up_req->hdr;
3847	bool hotplug = false;
3848
3849	if (hdr->broadcast) {
3850		const u8 *guid = NULL;
3851
3852		if (msg->req_type == DP_CONNECTION_STATUS_NOTIFY)
3853			guid = msg->u.conn_stat.guid;
3854		else if (msg->req_type == DP_RESOURCE_STATUS_NOTIFY)
3855			guid = msg->u.resource_stat.guid;
3856
3857		if (guid)
3858			mstb = drm_dp_get_mst_branch_device_by_guid(mgr, guid);
3859	} else {
3860		mstb = drm_dp_get_mst_branch_device(mgr, hdr->lct, hdr->rad);
3861	}
3862
3863	if (!mstb) {
3864		DRM_DEBUG_KMS("Got MST reply from unknown device %d\n",
3865			      hdr->lct);
3866		return false;
3867	}
3868
3869	/* TODO: Add missing handler for DP_RESOURCE_STATUS_NOTIFY events */
3870	if (msg->req_type == DP_CONNECTION_STATUS_NOTIFY) {
3871		drm_dp_mst_handle_conn_stat(mstb, &msg->u.conn_stat);
3872		hotplug = true;
3873	}
3874
3875	drm_dp_mst_topology_put_mstb(mstb);
3876	return hotplug;
3877}
3878
3879static void drm_dp_mst_up_req_work(struct work_struct *work)
3880{
3881	struct drm_dp_mst_topology_mgr *mgr =
3882		container_of(work, struct drm_dp_mst_topology_mgr,
3883			     up_req_work);
3884	struct drm_dp_pending_up_req *up_req;
3885	bool send_hotplug = false;
3886
3887	mutex_lock(&mgr->probe_lock);
3888	while (true) {
3889		mutex_lock(&mgr->up_req_lock);
3890		up_req = list_first_entry_or_null(&mgr->up_req_list,
3891						  struct drm_dp_pending_up_req,
3892						  next);
3893		if (up_req)
3894			list_del(&up_req->next);
3895		mutex_unlock(&mgr->up_req_lock);
3896
3897		if (!up_req)
3898			break;
3899
3900		send_hotplug |= drm_dp_mst_process_up_req(mgr, up_req);
3901		kfree(up_req);
3902	}
3903	mutex_unlock(&mgr->probe_lock);
3904
3905	if (send_hotplug)
3906		drm_kms_helper_hotplug_event(mgr->dev);
3907}
3908
3909static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
3910{
3911	struct drm_dp_pending_up_req *up_req;
3912
3913	if (!drm_dp_get_one_sb_msg(mgr, true, NULL))
3914		goto out;
3915
3916	if (!mgr->up_req_recv.have_eomt)
3917		return 0;
3918
3919	up_req = kzalloc(sizeof(*up_req), GFP_KERNEL);
3920	if (!up_req) {
3921		DRM_ERROR("Not enough memory to process MST up req\n");
3922		return -ENOMEM;
3923	}
3924	INIT_LIST_HEAD(&up_req->next);
3925
3926	drm_dp_sideband_parse_req(&mgr->up_req_recv, &up_req->msg);
3927
3928	if (up_req->msg.req_type != DP_CONNECTION_STATUS_NOTIFY &&
3929	    up_req->msg.req_type != DP_RESOURCE_STATUS_NOTIFY) {
3930		DRM_DEBUG_KMS("Received unknown up req type, ignoring: %x\n",
3931			      up_req->msg.req_type);
3932		kfree(up_req);
3933		goto out;
3934	}
3935
3936	drm_dp_send_up_ack_reply(mgr, mgr->mst_primary, up_req->msg.req_type,
3937				 false);
3938
3939	if (up_req->msg.req_type == DP_CONNECTION_STATUS_NOTIFY) {
3940		const struct drm_dp_connection_status_notify *conn_stat =
3941			&up_req->msg.u.conn_stat;
3942
3943		DRM_DEBUG_KMS("Got CSN: pn: %d ldps:%d ddps: %d mcs: %d ip: %d pdt: %d\n",
3944			      conn_stat->port_number,
3945			      conn_stat->legacy_device_plug_status,
3946			      conn_stat->displayport_device_plug_status,
3947			      conn_stat->message_capability_status,
3948			      conn_stat->input_port,
3949			      conn_stat->peer_device_type);
3950	} else if (up_req->msg.req_type == DP_RESOURCE_STATUS_NOTIFY) {
3951		const struct drm_dp_resource_status_notify *res_stat =
3952			&up_req->msg.u.resource_stat;
3953
3954		DRM_DEBUG_KMS("Got RSN: pn: %d avail_pbn %d\n",
3955			      res_stat->port_number,
3956			      res_stat->available_pbn);
3957	}
3958
3959	up_req->hdr = mgr->up_req_recv.initial_hdr;
3960	mutex_lock(&mgr->up_req_lock);
3961	list_add_tail(&up_req->next, &mgr->up_req_list);
3962	mutex_unlock(&mgr->up_req_lock);
3963	queue_work(system_long_wq, &mgr->up_req_work);
3964
3965out:
3966	memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
3967	return 0;
3968}
3969
3970/**
3971 * drm_dp_mst_hpd_irq() - MST hotplug IRQ notify
3972 * @mgr: manager to notify irq for.
3973 * @esi: 4 bytes from SINK_COUNT_ESI
3974 * @handled: whether the hpd interrupt was consumed or not
3975 *
3976 * This should be called from the driver when it detects a short IRQ,
3977 * along with the value of the DEVICE_SERVICE_IRQ_VECTOR_ESI0. The
3978 * topology manager will process the sideband messages received as a result
3979 * of this.
3980 */
3981int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled)
3982{
3983	int ret = 0;
3984	int sc;
3985	*handled = false;
3986	sc = esi[0] & 0x3f;
3987
3988	if (sc != mgr->sink_count) {
3989		mgr->sink_count = sc;
3990		*handled = true;
3991	}
3992
3993	if (esi[1] & DP_DOWN_REP_MSG_RDY) {
3994		ret = drm_dp_mst_handle_down_rep(mgr);
3995		*handled = true;
3996	}
3997
3998	if (esi[1] & DP_UP_REQ_MSG_RDY) {
3999		ret |= drm_dp_mst_handle_up_req(mgr);
4000		*handled = true;
4001	}
4002
4003	drm_dp_mst_kick_tx(mgr);
4004	return ret;
4005}
4006EXPORT_SYMBOL(drm_dp_mst_hpd_irq);
4007
4008/**
4009 * drm_dp_mst_detect_port() - get connection status for an MST port
4010 * @connector: DRM connector for this port
4011 * @ctx: The acquisition context to use for grabbing locks
4012 * @mgr: manager for this port
4013 * @port: pointer to a port
4014 *
4015 * This returns the current connection state for a port.
4016 */
4017int
4018drm_dp_mst_detect_port(struct drm_connector *connector,
4019		       struct drm_modeset_acquire_ctx *ctx,
4020		       struct drm_dp_mst_topology_mgr *mgr,
4021		       struct drm_dp_mst_port *port)
4022{
4023	int ret;
4024
4025	/* we need to search for the port in the mgr in case it's gone */
4026	port = drm_dp_mst_topology_get_port_validated(mgr, port);
4027	if (!port)
4028		return connector_status_disconnected;
4029
4030	ret = drm_modeset_lock(&mgr->base.lock, ctx);
4031	if (ret)
4032		goto out;
4033
4034	ret = connector_status_disconnected;
4035
4036	if (!port->ddps)
4037		goto out;
4038
4039	switch (port->pdt) {
4040	case DP_PEER_DEVICE_NONE:
4041	case DP_PEER_DEVICE_MST_BRANCHING:
4042		if (!port->mcs)
4043			ret = connector_status_connected;
4044		break;
4045
4046	case DP_PEER_DEVICE_SST_SINK:
4047		ret = connector_status_connected;
4048		/* for logical ports - cache the EDID */
4049		if (port->port_num >= 8 && !port->cached_edid) {
4050			port->cached_edid = drm_get_edid(connector, &port->aux.ddc);
4051		}
4052		break;
4053	case DP_PEER_DEVICE_DP_LEGACY_CONV:
4054		if (port->ldps)
4055			ret = connector_status_connected;
4056		break;
4057	}
4058out:
4059	drm_dp_mst_topology_put_port(port);
4060	return ret;
4061}
4062EXPORT_SYMBOL(drm_dp_mst_detect_port);
4063
4064/**
4065 * drm_dp_mst_get_edid() - get EDID for an MST port
4066 * @connector: toplevel connector to get EDID for
4067 * @mgr: manager for this port
4068 * @port: unverified pointer to a port.
4069 *
4070 * This returns an EDID for the port connected to a connector,
4071 * It validates the pointer still exists so the caller doesn't require a
4072 * reference.
4073 */
4074struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
4075{
4076	struct edid *edid = NULL;
4077
4078	/* we need to search for the port in the mgr in case it's gone */
4079	port = drm_dp_mst_topology_get_port_validated(mgr, port);
4080	if (!port)
4081		return NULL;
4082
4083	if (port->cached_edid)
4084		edid = drm_edid_duplicate(port->cached_edid);
4085	else {
4086		edid = drm_get_edid(connector, &port->aux.ddc);
4087	}
4088	port->has_audio = drm_detect_monitor_audio(edid);
4089	drm_dp_mst_topology_put_port(port);
4090	return edid;
4091}
4092EXPORT_SYMBOL(drm_dp_mst_get_edid);
4093
4094/**
4095 * drm_dp_find_vcpi_slots() - Find VCPI slots for this PBN value
4096 * @mgr: manager to use
4097 * @pbn: payload bandwidth to convert into slots.
4098 *
4099 * Calculate the number of VCPI slots that will be required for the given PBN
4100 * value. This function is deprecated, and should not be used in atomic
4101 * drivers.
4102 *
4103 * RETURNS:
4104 * The total slots required for this port, or error.
4105 */
4106int drm_dp_find_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,
4107			   int pbn)
4108{
4109	int num_slots;
4110
4111	num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
4112
4113	/* max. time slots - one slot for MTP header */
4114	if (num_slots > 63)
4115		return -ENOSPC;
4116	return num_slots;
4117}
4118EXPORT_SYMBOL(drm_dp_find_vcpi_slots);
4119
4120static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
4121			    struct drm_dp_vcpi *vcpi, int pbn, int slots)
4122{
4123	int ret;
4124
4125	/* max. time slots - one slot for MTP header */
4126	if (slots > 63)
4127		return -ENOSPC;
4128
4129	vcpi->pbn = pbn;
4130	vcpi->aligned_pbn = slots * mgr->pbn_div;
4131	vcpi->num_slots = slots;
4132
4133	ret = drm_dp_mst_assign_payload_id(mgr, vcpi);
4134	if (ret < 0)
4135		return ret;
4136	return 0;
4137}
4138
4139/**
4140 * drm_dp_atomic_find_vcpi_slots() - Find and add VCPI slots to the state
4141 * @state: global atomic state
4142 * @mgr: MST topology manager for the port
4143 * @port: port to find vcpi slots for
4144 * @pbn: bandwidth required for the mode in PBN
4145 * @pbn_div: divider for DSC mode that takes FEC into account
4146 *
4147 * Allocates VCPI slots to @port, replacing any previous VCPI allocations it
4148 * may have had. Any atomic drivers which support MST must call this function
4149 * in their &drm_encoder_helper_funcs.atomic_check() callback to change the
4150 * current VCPI allocation for the new state, but only when
4151 * &drm_crtc_state.mode_changed or &drm_crtc_state.connectors_changed is set
4152 * to ensure compatibility with userspace applications that still use the
4153 * legacy modesetting UAPI.
4154 *
4155 * Allocations set by this function are not checked against the bandwidth
4156 * restraints of @mgr until the driver calls drm_dp_mst_atomic_check().
4157 *
4158 * Additionally, it is OK to call this function multiple times on the same
4159 * @port as needed. It is not OK however, to call this function and
4160 * drm_dp_atomic_release_vcpi_slots() in the same atomic check phase.
4161 *
4162 * See also:
4163 * drm_dp_atomic_release_vcpi_slots()
4164 * drm_dp_mst_atomic_check()
4165 *
4166 * Returns:
4167 * Total slots in the atomic state assigned for this port, or a negative error
4168 * code if the port no longer exists
4169 */
4170int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
4171				  struct drm_dp_mst_topology_mgr *mgr,
4172				  struct drm_dp_mst_port *port, int pbn,
4173				  int pbn_div)
4174{
4175	struct drm_dp_mst_topology_state *topology_state;
4176	struct drm_dp_vcpi_allocation *pos, *vcpi = NULL;
4177	int prev_slots, prev_bw, req_slots;
4178
4179	topology_state = drm_atomic_get_mst_topology_state(state, mgr);
4180	if (IS_ERR(topology_state))
4181		return PTR_ERR(topology_state);
4182
4183	/* Find the current allocation for this port, if any */
4184	list_for_each_entry(pos, &topology_state->vcpis, next) {
4185		if (pos->port == port) {
4186			vcpi = pos;
4187			prev_slots = vcpi->vcpi;
4188			prev_bw = vcpi->pbn;
4189
4190			/*
4191			 * This should never happen, unless the driver tries
4192			 * releasing and allocating the same VCPI allocation,
4193			 * which is an error
4194			 */
4195			if (WARN_ON(!prev_slots)) {
4196				DRM_ERROR("cannot allocate and release VCPI on [MST PORT:%p] in the same state\n",
4197					  port);
4198				return -EINVAL;
4199			}
4200
4201			break;
4202		}
4203	}
4204	if (!vcpi) {
4205		prev_slots = 0;
4206		prev_bw = 0;
4207	}
4208
4209	if (pbn_div <= 0)
4210		pbn_div = mgr->pbn_div;
4211
4212	req_slots = DIV_ROUND_UP(pbn, pbn_div);
4213
4214	DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] [MST PORT:%p] VCPI %d -> %d\n",
4215			 port->connector->base.id, port->connector->name,
4216			 port, prev_slots, req_slots);
4217	DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] [MST PORT:%p] PBN %d -> %d\n",
4218			 port->connector->base.id, port->connector->name,
4219			 port, prev_bw, pbn);
4220
4221	/* Add the new allocation to the state */
4222	if (!vcpi) {
4223		vcpi = kzalloc(sizeof(*vcpi), GFP_KERNEL);
4224		if (!vcpi)
4225			return -ENOMEM;
4226
4227		drm_dp_mst_get_port_malloc(port);
4228		vcpi->port = port;
4229		list_add(&vcpi->next, &topology_state->vcpis);
4230	}
4231	vcpi->vcpi = req_slots;
4232	vcpi->pbn = pbn;
4233
4234	return req_slots;
4235}
4236EXPORT_SYMBOL(drm_dp_atomic_find_vcpi_slots);
4237
4238/**
4239 * drm_dp_atomic_release_vcpi_slots() - Release allocated vcpi slots
4240 * @state: global atomic state
4241 * @mgr: MST topology manager for the port
4242 * @port: The port to release the VCPI slots from
4243 *
4244 * Releases any VCPI slots that have been allocated to a port in the atomic
4245 * state. Any atomic drivers which support MST must call this function in
4246 * their &drm_connector_helper_funcs.atomic_check() callback when the
4247 * connector will no longer have VCPI allocated (e.g. because its CRTC was
4248 * removed) when it had VCPI allocated in the previous atomic state.
4249 *
4250 * It is OK to call this even if @port has been removed from the system.
4251 * Additionally, it is OK to call this function multiple times on the same
4252 * @port as needed. It is not OK however, to call this function and
4253 * drm_dp_atomic_find_vcpi_slots() on the same @port in a single atomic check
4254 * phase.
4255 *
4256 * See also:
4257 * drm_dp_atomic_find_vcpi_slots()
4258 * drm_dp_mst_atomic_check()
4259 *
4260 * Returns:
4261 * 0 if all slots for this port were added back to
4262 * &drm_dp_mst_topology_state.avail_slots or negative error code
4263 */
4264int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
4265				     struct drm_dp_mst_topology_mgr *mgr,
4266				     struct drm_dp_mst_port *port)
4267{
4268	struct drm_dp_mst_topology_state *topology_state;
4269	struct drm_dp_vcpi_allocation *pos;
4270	bool found = false;
4271
4272	topology_state = drm_atomic_get_mst_topology_state(state, mgr);
4273	if (IS_ERR(topology_state))
4274		return PTR_ERR(topology_state);
4275
4276	list_for_each_entry(pos, &topology_state->vcpis, next) {
4277		if (pos->port == port) {
4278			found = true;
4279			break;
4280		}
4281	}
4282	if (WARN_ON(!found)) {
4283		DRM_ERROR("no VCPI for [MST PORT:%p] found in mst state %p\n",
4284			  port, &topology_state->base);
4285		return -EINVAL;
4286	}
4287
4288	DRM_DEBUG_ATOMIC("[MST PORT:%p] VCPI %d -> 0\n", port, pos->vcpi);
4289	if (pos->vcpi) {
4290		drm_dp_mst_put_port_malloc(port);
4291		pos->vcpi = 0;
4292		pos->pbn = 0;
4293	}
4294
4295	return 0;
4296}
4297EXPORT_SYMBOL(drm_dp_atomic_release_vcpi_slots);
4298
4299/**
4300 * drm_dp_mst_allocate_vcpi() - Allocate a virtual channel
4301 * @mgr: manager for this port
4302 * @port: port to allocate a virtual channel for.
4303 * @pbn: payload bandwidth number to request
4304 * @slots: returned number of slots for this PBN.
4305 */
4306bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
4307			      struct drm_dp_mst_port *port, int pbn, int slots)
4308{
4309	int ret;
4310
4311	if (slots < 0)
4312		return false;
4313
4314	port = drm_dp_mst_topology_get_port_validated(mgr, port);
4315	if (!port)
4316		return false;
4317
4318	if (port->vcpi.vcpi > 0) {
4319		DRM_DEBUG_KMS("payload: vcpi %d already allocated for pbn %d - requested pbn %d\n",
4320			      port->vcpi.vcpi, port->vcpi.pbn, pbn);
4321		if (pbn == port->vcpi.pbn) {
4322			drm_dp_mst_topology_put_port(port);
4323			return true;
4324		}
4325	}
4326
4327	ret = drm_dp_init_vcpi(mgr, &port->vcpi, pbn, slots);
4328	if (ret) {
4329		DRM_DEBUG_KMS("failed to init vcpi slots=%d max=63 ret=%d\n",
4330			      DIV_ROUND_UP(pbn, mgr->pbn_div), ret);
4331		drm_dp_mst_topology_put_port(port);
4332		goto out;
4333	}
4334	DRM_DEBUG_KMS("initing vcpi for pbn=%d slots=%d\n",
4335		      pbn, port->vcpi.num_slots);
4336
4337	/* Keep port allocated until its payload has been removed */
4338	drm_dp_mst_get_port_malloc(port);
4339	drm_dp_mst_topology_put_port(port);
4340	return true;
4341out:
4342	return false;
4343}
4344EXPORT_SYMBOL(drm_dp_mst_allocate_vcpi);
4345
4346int drm_dp_mst_get_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
4347{
4348	int slots = 0;
4349
4350	port = drm_dp_mst_topology_get_port_validated(mgr, port);
4351	if (!port)
4352		return slots;
4353
4354	slots = port->vcpi.num_slots;
4355	drm_dp_mst_topology_put_port(port);
4356	return slots;
4357}
4358EXPORT_SYMBOL(drm_dp_mst_get_vcpi_slots);
4359
4360/**
4361 * drm_dp_mst_reset_vcpi_slots() - Reset number of slots to 0 for VCPI
4362 * @mgr: manager for this port
4363 * @port: unverified pointer to a port.
4364 *
4365 * This just resets the number of slots for the ports VCPI for later programming.
4366 */
4367void drm_dp_mst_reset_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
4368{
4369	/*
4370	 * A port with VCPI will remain allocated until its VCPI is
4371	 * released, no verified ref needed
4372	 */
4373
4374	port->vcpi.num_slots = 0;
4375}
4376EXPORT_SYMBOL(drm_dp_mst_reset_vcpi_slots);
4377
4378/**
4379 * drm_dp_mst_deallocate_vcpi() - deallocate a VCPI
4380 * @mgr: manager for this port
4381 * @port: port to deallocate vcpi for
4382 *
4383 * This can be called unconditionally, regardless of whether
4384 * drm_dp_mst_allocate_vcpi() succeeded or not.
4385 */
4386void drm_dp_mst_deallocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
4387				struct drm_dp_mst_port *port)
4388{
4389	if (!port->vcpi.vcpi)
4390		return;
4391
4392	drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi);
4393	port->vcpi.num_slots = 0;
4394	port->vcpi.pbn = 0;
4395	port->vcpi.aligned_pbn = 0;
4396	port->vcpi.vcpi = 0;
4397	drm_dp_mst_put_port_malloc(port);
4398}
4399EXPORT_SYMBOL(drm_dp_mst_deallocate_vcpi);
4400
4401static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
4402				     int id, struct drm_dp_payload *payload)
4403{
4404	u8 payload_alloc[3], status;
4405	int ret;
4406	int retries = 0;
4407
4408	drm_dp_dpcd_writeb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS,
4409			   DP_PAYLOAD_TABLE_UPDATED);
4410
4411	payload_alloc[0] = id;
4412	payload_alloc[1] = payload->start_slot;
4413	payload_alloc[2] = payload->num_slots;
4414
4415	ret = drm_dp_dpcd_write(mgr->aux, DP_PAYLOAD_ALLOCATE_SET, payload_alloc, 3);
4416	if (ret != 3) {
4417		DRM_DEBUG_KMS("failed to write payload allocation %d\n", ret);
4418		goto fail;
4419	}
4420
4421retry:
4422	ret = drm_dp_dpcd_readb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
4423	if (ret < 0) {
4424		DRM_DEBUG_KMS("failed to read payload table status %d\n", ret);
4425		goto fail;
4426	}
4427
4428	if (!(status & DP_PAYLOAD_TABLE_UPDATED)) {
4429		retries++;
4430		if (retries < 20) {
4431			usleep_range(10000, 20000);
4432			goto retry;
4433		}
4434		DRM_DEBUG_KMS("status not set after read payload table status %d\n", status);
4435		ret = -EINVAL;
4436		goto fail;
4437	}
4438	ret = 0;
4439fail:
4440	return ret;
4441}
4442
4443static int do_get_act_status(struct drm_dp_aux *aux)
4444{
4445	int ret;
4446	u8 status;
4447
4448	ret = drm_dp_dpcd_readb(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
4449	if (ret < 0)
4450		return ret;
4451
4452	return status;
4453}
4454
4455/**
4456 * drm_dp_check_act_status() - Polls for ACT handled status.
4457 * @mgr: manager to use
4458 *
4459 * Tries waiting for the MST hub to finish updating it's payload table by
4460 * polling for the ACT handled bit for up to 3 seconds (yes-some hubs really
4461 * take that long).
4462 *
4463 * Returns:
4464 * 0 if the ACT was handled in time, negative error code on failure.
4465 */
4466int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr)
4467{
4468	/*
4469	 * There doesn't seem to be any recommended retry count or timeout in
4470	 * the MST specification. Since some hubs have been observed to take
4471	 * over 1 second to update their payload allocations under certain
4472	 * conditions, we use a rather large timeout value.
4473	 */
4474	const int timeout_ms = 3000;
4475	int ret, status;
4476
4477	ret = readx_poll_timeout(do_get_act_status, mgr->aux, status,
4478				 status & DP_PAYLOAD_ACT_HANDLED || status < 0,
4479				 200, timeout_ms * USEC_PER_MSEC);
4480	if (ret < 0 && status >= 0) {
4481		DRM_ERROR("Failed to get ACT after %dms, last status: %02x\n",
4482			  timeout_ms, status);
4483		return -EINVAL;
4484	} else if (status < 0) {
4485		/*
4486		 * Failure here isn't unexpected - the hub may have
4487		 * just been unplugged
4488		 */
4489		DRM_DEBUG_KMS("Failed to read payload table status: %d\n",
4490			      status);
4491		return status;
4492	}
4493
4494	return 0;
4495}
4496EXPORT_SYMBOL(drm_dp_check_act_status);
4497
4498/**
4499 * drm_dp_calc_pbn_mode() - Calculate the PBN for a mode.
4500 * @clock: dot clock for the mode
4501 * @bpp: bpp for the mode.
4502 * @dsc: DSC mode. If true, bpp has units of 1/16 of a bit per pixel
4503 *
4504 * This uses the formula in the spec to calculate the PBN value for a mode.
4505 */
4506int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc)
4507{
4508	/*
4509	 * margin 5300ppm + 300ppm ~ 0.6% as per spec, factor is 1.006
4510	 * The unit of 54/64Mbytes/sec is an arbitrary unit chosen based on
4511	 * common multiplier to render an integer PBN for all link rate/lane
4512	 * counts combinations
4513	 * calculate
4514	 * peak_kbps *= (1006/1000)
4515	 * peak_kbps *= (64/54)
4516	 * peak_kbps *= 8    convert to bytes
4517	 *
4518	 * If the bpp is in units of 1/16, further divide by 16. Put this
4519	 * factor in the numerator rather than the denominator to avoid
4520	 * integer overflow
4521	 */
4522
4523	if (dsc)
4524		return DIV_ROUND_UP_ULL(mul_u32_u32(clock * (bpp / 16), 64 * 1006),
4525					8 * 54 * 1000 * 1000);
4526
4527	return DIV_ROUND_UP_ULL(mul_u32_u32(clock * bpp, 64 * 1006),
4528				8 * 54 * 1000 * 1000);
4529}
4530EXPORT_SYMBOL(drm_dp_calc_pbn_mode);
4531
4532/* we want to kick the TX after we've ack the up/down IRQs. */
4533static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr)
4534{
4535	queue_work(system_long_wq, &mgr->tx_work);
4536}
4537
4538static void drm_dp_mst_dump_mstb(struct seq_file *m,
4539				 struct drm_dp_mst_branch *mstb)
4540{
4541	struct drm_dp_mst_port *port;
4542	int tabs = mstb->lct;
4543	char prefix[10];
4544	int i;
4545
4546	for (i = 0; i < tabs; i++)
4547		prefix[i] = '\t';
4548	prefix[i] = '\0';
4549
4550	seq_printf(m, "%smst: %p, %d\n", prefix, mstb, mstb->num_ports);
4551	list_for_each_entry(port, &mstb->ports, next) {
4552		seq_printf(m, "%sport: %d: input: %d: pdt: %d, ddps: %d ldps: %d, sdp: %d/%d, %p, conn: %p\n", prefix, port->port_num, port->input, port->pdt, port->ddps, port->ldps, port->num_sdp_streams, port->num_sdp_stream_sinks, port, port->connector);
4553		if (port->mstb)
4554			drm_dp_mst_dump_mstb(m, port->mstb);
4555	}
4556}
4557
4558#define DP_PAYLOAD_TABLE_SIZE		64
4559
4560static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
4561				  char *buf)
4562{
4563	int i;
4564
4565	for (i = 0; i < DP_PAYLOAD_TABLE_SIZE; i += 16) {
4566		if (drm_dp_dpcd_read(mgr->aux,
4567				     DP_PAYLOAD_TABLE_UPDATE_STATUS + i,
4568				     &buf[i], 16) != 16)
4569			return false;
4570	}
4571	return true;
4572}
4573
4574static void fetch_monitor_name(struct drm_dp_mst_topology_mgr *mgr,
4575			       struct drm_dp_mst_port *port, char *name,
4576			       int namelen)
4577{
4578	struct edid *mst_edid;
4579
4580	mst_edid = drm_dp_mst_get_edid(port->connector, mgr, port);
4581	drm_edid_get_monitor_name(mst_edid, name, namelen);
4582}
4583
4584/**
4585 * drm_dp_mst_dump_topology(): dump topology to seq file.
4586 * @m: seq_file to dump output to
4587 * @mgr: manager to dump current topology for.
4588 *
4589 * helper to dump MST topology to a seq file for debugfs.
4590 */
4591void drm_dp_mst_dump_topology(struct seq_file *m,
4592			      struct drm_dp_mst_topology_mgr *mgr)
4593{
4594	int i;
4595	struct drm_dp_mst_port *port;
4596
4597	mutex_lock(&mgr->lock);
4598	if (mgr->mst_primary)
4599		drm_dp_mst_dump_mstb(m, mgr->mst_primary);
4600
4601	/* dump VCPIs */
4602	mutex_unlock(&mgr->lock);
4603
4604	mutex_lock(&mgr->payload_lock);
4605	seq_printf(m, "vcpi: %lx %lx %d\n", mgr->payload_mask, mgr->vcpi_mask,
4606		mgr->max_payloads);
4607
4608	for (i = 0; i < mgr->max_payloads; i++) {
4609		if (mgr->proposed_vcpis[i]) {
4610			char name[14];
4611
4612			port = container_of(mgr->proposed_vcpis[i], struct drm_dp_mst_port, vcpi);
4613			fetch_monitor_name(mgr, port, name, sizeof(name));
4614			seq_printf(m, "vcpi %d: %d %d %d sink name: %s\n", i,
4615				   port->port_num, port->vcpi.vcpi,
4616				   port->vcpi.num_slots,
4617				   (*name != 0) ? name :  "Unknown");
4618		} else
4619			seq_printf(m, "vcpi %d:unused\n", i);
4620	}
4621	for (i = 0; i < mgr->max_payloads; i++) {
4622		seq_printf(m, "payload %d: %d, %d, %d\n",
4623			   i,
4624			   mgr->payloads[i].payload_state,
4625			   mgr->payloads[i].start_slot,
4626			   mgr->payloads[i].num_slots);
4627
4628
4629	}
4630	mutex_unlock(&mgr->payload_lock);
4631
4632	mutex_lock(&mgr->lock);
4633	if (mgr->mst_primary) {
4634		u8 buf[DP_PAYLOAD_TABLE_SIZE];
4635		int ret;
4636
4637		ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, buf, DP_RECEIVER_CAP_SIZE);
4638		if (ret) {
4639			seq_printf(m, "dpcd read failed\n");
4640			goto out;
4641		}
4642		seq_printf(m, "dpcd: %*ph\n", DP_RECEIVER_CAP_SIZE, buf);
4643
4644		ret = drm_dp_dpcd_read(mgr->aux, DP_FAUX_CAP, buf, 2);
4645		if (ret) {
4646			seq_printf(m, "faux/mst read failed\n");
4647			goto out;
4648		}
4649		seq_printf(m, "faux/mst: %*ph\n", 2, buf);
4650
4651		ret = drm_dp_dpcd_read(mgr->aux, DP_MSTM_CTRL, buf, 1);
4652		if (ret) {
4653			seq_printf(m, "mst ctrl read failed\n");
4654			goto out;
4655		}
4656		seq_printf(m, "mst ctrl: %*ph\n", 1, buf);
4657
4658		/* dump the standard OUI branch header */
4659		ret = drm_dp_dpcd_read(mgr->aux, DP_BRANCH_OUI, buf, DP_BRANCH_OUI_HEADER_SIZE);
4660		if (ret) {
4661			seq_printf(m, "branch oui read failed\n");
4662			goto out;
4663		}
4664		seq_printf(m, "branch oui: %*phN devid: ", 3, buf);
4665
4666		for (i = 0x3; i < 0x8 && buf[i]; i++)
4667			seq_printf(m, "%c", buf[i]);
4668		seq_printf(m, " revision: hw: %x.%x sw: %x.%x\n",
4669			   buf[0x9] >> 4, buf[0x9] & 0xf, buf[0xa], buf[0xb]);
4670		if (dump_dp_payload_table(mgr, buf))
4671			seq_printf(m, "payload table: %*ph\n", DP_PAYLOAD_TABLE_SIZE, buf);
4672	}
4673
4674out:
4675	mutex_unlock(&mgr->lock);
4676
4677}
4678EXPORT_SYMBOL(drm_dp_mst_dump_topology);
4679
4680static void drm_dp_tx_work(struct work_struct *work)
4681{
4682	struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct drm_dp_mst_topology_mgr, tx_work);
4683
4684	mutex_lock(&mgr->qlock);
4685	if (!list_empty(&mgr->tx_msg_downq))
4686		process_single_down_tx_qlock(mgr);
4687	mutex_unlock(&mgr->qlock);
4688}
4689
4690static inline void
4691drm_dp_delayed_destroy_port(struct drm_dp_mst_port *port)
4692{
4693	drm_dp_port_set_pdt(port, DP_PEER_DEVICE_NONE, port->mcs);
4694
4695	if (port->connector) {
4696		drm_connector_unregister(port->connector);
4697		drm_connector_put(port->connector);
4698	}
4699
4700	drm_dp_mst_put_port_malloc(port);
4701}
4702
4703static inline void
4704drm_dp_delayed_destroy_mstb(struct drm_dp_mst_branch *mstb)
4705{
4706	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
4707	struct drm_dp_mst_port *port, *port_tmp;
4708	struct drm_dp_sideband_msg_tx *txmsg, *txmsg_tmp;
4709	bool wake_tx = false;
4710
4711	mutex_lock(&mgr->lock);
4712	list_for_each_entry_safe(port, port_tmp, &mstb->ports, next) {
4713		list_del(&port->next);
4714		drm_dp_mst_topology_put_port(port);
4715	}
4716	mutex_unlock(&mgr->lock);
4717
4718	/* drop any tx slot msg */
4719	mutex_lock(&mstb->mgr->qlock);
4720	list_for_each_entry_safe(txmsg, txmsg_tmp, &mgr->tx_msg_downq, next) {
4721		if (txmsg->dst != mstb)
4722			continue;
4723
4724		txmsg->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
4725		list_del(&txmsg->next);
4726		wake_tx = true;
4727	}
4728	mutex_unlock(&mstb->mgr->qlock);
4729
4730	if (wake_tx)
4731		wake_up_all(&mstb->mgr->tx_waitq);
4732
4733	drm_dp_mst_put_mstb_malloc(mstb);
4734}
4735
4736static void drm_dp_delayed_destroy_work(struct work_struct *work)
4737{
4738	struct drm_dp_mst_topology_mgr *mgr =
4739		container_of(work, struct drm_dp_mst_topology_mgr,
4740			     delayed_destroy_work);
4741	bool send_hotplug = false, go_again;
4742
4743	/*
4744	 * Not a regular list traverse as we have to drop the destroy
4745	 * connector lock before destroying the mstb/port, to avoid AB->BA
4746	 * ordering between this lock and the config mutex.
4747	 */
4748	do {
4749		go_again = false;
4750
4751		for (;;) {
4752			struct drm_dp_mst_branch *mstb;
4753
4754			mutex_lock(&mgr->delayed_destroy_lock);
4755			mstb = list_first_entry_or_null(&mgr->destroy_branch_device_list,
4756							struct drm_dp_mst_branch,
4757							destroy_next);
4758			if (mstb)
4759				list_del(&mstb->destroy_next);
4760			mutex_unlock(&mgr->delayed_destroy_lock);
4761
4762			if (!mstb)
4763				break;
4764
4765			drm_dp_delayed_destroy_mstb(mstb);
4766			go_again = true;
4767		}
4768
4769		for (;;) {
4770			struct drm_dp_mst_port *port;
4771
4772			mutex_lock(&mgr->delayed_destroy_lock);
4773			port = list_first_entry_or_null(&mgr->destroy_port_list,
4774							struct drm_dp_mst_port,
4775							next);
4776			if (port)
4777				list_del(&port->next);
4778			mutex_unlock(&mgr->delayed_destroy_lock);
4779
4780			if (!port)
4781				break;
4782
4783			drm_dp_delayed_destroy_port(port);
4784			send_hotplug = true;
4785			go_again = true;
4786		}
4787	} while (go_again);
4788
4789	if (send_hotplug)
4790		drm_kms_helper_hotplug_event(mgr->dev);
4791}
4792
4793static struct drm_private_state *
4794drm_dp_mst_duplicate_state(struct drm_private_obj *obj)
4795{
4796	struct drm_dp_mst_topology_state *state, *old_state =
4797		to_dp_mst_topology_state(obj->state);
4798	struct drm_dp_vcpi_allocation *pos, *vcpi;
4799
4800	state = kmemdup(old_state, sizeof(*state), GFP_KERNEL);
4801	if (!state)
4802		return NULL;
4803
4804	__drm_atomic_helper_private_obj_duplicate_state(obj, &state->base);
4805
4806	INIT_LIST_HEAD(&state->vcpis);
4807
4808	list_for_each_entry(pos, &old_state->vcpis, next) {
4809		/* Prune leftover freed VCPI allocations */
4810		if (!pos->vcpi)
4811			continue;
4812
4813		vcpi = kmemdup(pos, sizeof(*vcpi), GFP_KERNEL);
4814		if (!vcpi)
4815			goto fail;
4816
4817		drm_dp_mst_get_port_malloc(vcpi->port);
4818		list_add(&vcpi->next, &state->vcpis);
4819	}
4820
4821	return &state->base;
4822
4823fail:
4824	list_for_each_entry_safe(pos, vcpi, &state->vcpis, next) {
4825		drm_dp_mst_put_port_malloc(pos->port);
4826		kfree(pos);
4827	}
4828	kfree(state);
4829
4830	return NULL;
4831}
4832
4833static void drm_dp_mst_destroy_state(struct drm_private_obj *obj,
4834				     struct drm_private_state *state)
4835{
4836	struct drm_dp_mst_topology_state *mst_state =
4837		to_dp_mst_topology_state(state);
4838	struct drm_dp_vcpi_allocation *pos, *tmp;
4839
4840	list_for_each_entry_safe(pos, tmp, &mst_state->vcpis, next) {
4841		/* We only keep references to ports with non-zero VCPIs */
4842		if (pos->vcpi)
4843			drm_dp_mst_put_port_malloc(pos->port);
4844		kfree(pos);
4845	}
4846
4847	kfree(mst_state);
4848}
4849
4850static bool drm_dp_mst_port_downstream_of_branch(struct drm_dp_mst_port *port,
4851						 struct drm_dp_mst_branch *branch)
4852{
4853	while (port->parent) {
4854		if (port->parent == branch)
4855			return true;
4856
4857		if (port->parent->port_parent)
4858			port = port->parent->port_parent;
4859		else
4860			break;
4861	}
4862	return false;
4863}
4864
4865static int
4866drm_dp_mst_atomic_check_port_bw_limit(struct drm_dp_mst_port *port,
4867				      struct drm_dp_mst_topology_state *state);
4868
4869static int
4870drm_dp_mst_atomic_check_mstb_bw_limit(struct drm_dp_mst_branch *mstb,
4871				      struct drm_dp_mst_topology_state *state)
4872{
4873	struct drm_dp_vcpi_allocation *vcpi;
4874	struct drm_dp_mst_port *port;
4875	int pbn_used = 0, ret;
4876	bool found = false;
4877
4878	/* Check that we have at least one port in our state that's downstream
4879	 * of this branch, otherwise we can skip this branch
4880	 */
4881	list_for_each_entry(vcpi, &state->vcpis, next) {
4882		if (!vcpi->pbn ||
4883		    !drm_dp_mst_port_downstream_of_branch(vcpi->port, mstb))
4884			continue;
4885
4886		found = true;
4887		break;
4888	}
4889	if (!found)
4890		return 0;
4891
4892	if (mstb->port_parent)
4893		DRM_DEBUG_ATOMIC("[MSTB:%p] [MST PORT:%p] Checking bandwidth limits on [MSTB:%p]\n",
4894				 mstb->port_parent->parent, mstb->port_parent,
4895				 mstb);
4896	else
4897		DRM_DEBUG_ATOMIC("[MSTB:%p] Checking bandwidth limits\n",
4898				 mstb);
4899
4900	list_for_each_entry(port, &mstb->ports, next) {
4901		ret = drm_dp_mst_atomic_check_port_bw_limit(port, state);
4902		if (ret < 0)
4903			return ret;
4904
4905		pbn_used += ret;
4906	}
4907
4908	return pbn_used;
4909}
4910
4911static int
4912drm_dp_mst_atomic_check_port_bw_limit(struct drm_dp_mst_port *port,
4913				      struct drm_dp_mst_topology_state *state)
4914{
4915	struct drm_dp_vcpi_allocation *vcpi;
4916	int pbn_used = 0;
4917
4918	if (port->pdt == DP_PEER_DEVICE_NONE)
4919		return 0;
4920
4921	if (drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
4922		bool found = false;
4923
4924		list_for_each_entry(vcpi, &state->vcpis, next) {
4925			if (vcpi->port != port)
4926				continue;
4927			if (!vcpi->pbn)
4928				return 0;
4929
4930			found = true;
4931			break;
4932		}
4933		if (!found)
4934			return 0;
4935
4936		/* This should never happen, as it means we tried to
4937		 * set a mode before querying the full_pbn
4938		 */
4939		if (WARN_ON(!port->full_pbn))
4940			return -EINVAL;
4941
4942		pbn_used = vcpi->pbn;
4943	} else {
4944		pbn_used = drm_dp_mst_atomic_check_mstb_bw_limit(port->mstb,
4945								 state);
4946		if (pbn_used <= 0)
4947			return pbn_used;
4948	}
4949
4950	if (pbn_used > port->full_pbn) {
4951		DRM_DEBUG_ATOMIC("[MSTB:%p] [MST PORT:%p] required PBN of %d exceeds port limit of %d\n",
4952				 port->parent, port, pbn_used,
4953				 port->full_pbn);
4954		return -ENOSPC;
4955	}
4956
4957	DRM_DEBUG_ATOMIC("[MSTB:%p] [MST PORT:%p] uses %d out of %d PBN\n",
4958			 port->parent, port, pbn_used, port->full_pbn);
4959
4960	return pbn_used;
4961}
4962
4963static inline int
4964drm_dp_mst_atomic_check_vcpi_alloc_limit(struct drm_dp_mst_topology_mgr *mgr,
4965					 struct drm_dp_mst_topology_state *mst_state)
4966{
4967	struct drm_dp_vcpi_allocation *vcpi;
4968	int avail_slots = 63, payload_count = 0;
4969
4970	list_for_each_entry(vcpi, &mst_state->vcpis, next) {
4971		/* Releasing VCPI is always OK-even if the port is gone */
4972		if (!vcpi->vcpi) {
4973			DRM_DEBUG_ATOMIC("[MST PORT:%p] releases all VCPI slots\n",
4974					 vcpi->port);
4975			continue;
4976		}
4977
4978		DRM_DEBUG_ATOMIC("[MST PORT:%p] requires %d vcpi slots\n",
4979				 vcpi->port, vcpi->vcpi);
4980
4981		avail_slots -= vcpi->vcpi;
4982		if (avail_slots < 0) {
4983			DRM_DEBUG_ATOMIC("[MST PORT:%p] not enough VCPI slots in mst state %p (avail=%d)\n",
4984					 vcpi->port, mst_state,
4985					 avail_slots + vcpi->vcpi);
4986			return -ENOSPC;
4987		}
4988
4989		if (++payload_count > mgr->max_payloads) {
4990			DRM_DEBUG_ATOMIC("[MST MGR:%p] state %p has too many payloads (max=%d)\n",
4991					 mgr, mst_state, mgr->max_payloads);
4992			return -EINVAL;
4993		}
4994	}
4995	DRM_DEBUG_ATOMIC("[MST MGR:%p] mst state %p VCPI avail=%d used=%d\n",
4996			 mgr, mst_state, avail_slots,
4997			 63 - avail_slots);
4998
4999	return 0;
5000}
5001
5002/**
5003 * drm_dp_mst_add_affected_dsc_crtcs
5004 * @state: Pointer to the new struct drm_dp_mst_topology_state
5005 * @mgr: MST topology manager
5006 *
5007 * Whenever there is a change in mst topology
5008 * DSC configuration would have to be recalculated
5009 * therefore we need to trigger modeset on all affected
5010 * CRTCs in that topology
5011 *
5012 * See also:
5013 * drm_dp_mst_atomic_enable_dsc()
5014 */
5015int drm_dp_mst_add_affected_dsc_crtcs(struct drm_atomic_state *state, struct drm_dp_mst_topology_mgr *mgr)
5016{
5017	struct drm_dp_mst_topology_state *mst_state;
5018	struct drm_dp_vcpi_allocation *pos;
5019	struct drm_connector *connector;
5020	struct drm_connector_state *conn_state;
5021	struct drm_crtc *crtc;
5022	struct drm_crtc_state *crtc_state;
5023
5024	mst_state = drm_atomic_get_mst_topology_state(state, mgr);
5025
5026	if (IS_ERR(mst_state))
5027		return -EINVAL;
5028
5029	list_for_each_entry(pos, &mst_state->vcpis, next) {
5030
5031		connector = pos->port->connector;
5032
5033		if (!connector)
5034			return -EINVAL;
5035
5036		conn_state = drm_atomic_get_connector_state(state, connector);
5037
5038		if (IS_ERR(conn_state))
5039			return PTR_ERR(conn_state);
5040
5041		crtc = conn_state->crtc;
5042
5043		if (!crtc)
5044			continue;
5045
5046		if (!drm_dp_mst_dsc_aux_for_port(pos->port))
5047			continue;
5048
5049		crtc_state = drm_atomic_get_crtc_state(mst_state->base.state, crtc);
5050
5051		if (IS_ERR(crtc_state))
5052			return PTR_ERR(crtc_state);
5053
5054		DRM_DEBUG_ATOMIC("[MST MGR:%p] Setting mode_changed flag on CRTC %p\n",
5055				 mgr, crtc);
5056
5057		crtc_state->mode_changed = true;
5058	}
5059	return 0;
5060}
5061EXPORT_SYMBOL(drm_dp_mst_add_affected_dsc_crtcs);
5062
5063/**
5064 * drm_dp_mst_atomic_enable_dsc - Set DSC Enable Flag to On/Off
5065 * @state: Pointer to the new drm_atomic_state
5066 * @port: Pointer to the affected MST Port
5067 * @pbn: Newly recalculated bw required for link with DSC enabled
5068 * @pbn_div: Divider to calculate correct number of pbn per slot
5069 * @enable: Boolean flag to enable or disable DSC on the port
5070 *
5071 * This function enables DSC on the given Port
5072 * by recalculating its vcpi from pbn provided
5073 * and sets dsc_enable flag to keep track of which
5074 * ports have DSC enabled
5075 *
5076 */
5077int drm_dp_mst_atomic_enable_dsc(struct drm_atomic_state *state,
5078				 struct drm_dp_mst_port *port,
5079				 int pbn, int pbn_div,
5080				 bool enable)
5081{
5082	struct drm_dp_mst_topology_state *mst_state;
5083	struct drm_dp_vcpi_allocation *pos;
5084	bool found = false;
5085	int vcpi = 0;
5086
5087	mst_state = drm_atomic_get_mst_topology_state(state, port->mgr);
5088
5089	if (IS_ERR(mst_state))
5090		return PTR_ERR(mst_state);
5091
5092	list_for_each_entry(pos, &mst_state->vcpis, next) {
5093		if (pos->port == port) {
5094			found = true;
5095			break;
5096		}
5097	}
5098
5099	if (!found) {
5100		DRM_DEBUG_ATOMIC("[MST PORT:%p] Couldn't find VCPI allocation in mst state %p\n",
5101				 port, mst_state);
5102		return -EINVAL;
5103	}
5104
5105	if (pos->dsc_enabled == enable) {
5106		DRM_DEBUG_ATOMIC("[MST PORT:%p] DSC flag is already set to %d, returning %d VCPI slots\n",
5107				 port, enable, pos->vcpi);
5108		vcpi = pos->vcpi;
5109	}
5110
5111	if (enable) {
5112		vcpi = drm_dp_atomic_find_vcpi_slots(state, port->mgr, port, pbn, pbn_div);
5113		DRM_DEBUG_ATOMIC("[MST PORT:%p] Enabling DSC flag, reallocating %d VCPI slots on the port\n",
5114				 port, vcpi);
5115		if (vcpi < 0)
5116			return -EINVAL;
5117	}
5118
5119	pos->dsc_enabled = enable;
5120
5121	return vcpi;
5122}
5123EXPORT_SYMBOL(drm_dp_mst_atomic_enable_dsc);
5124/**
5125 * drm_dp_mst_atomic_check - Check that the new state of an MST topology in an
5126 * atomic update is valid
5127 * @state: Pointer to the new &struct drm_dp_mst_topology_state
5128 *
5129 * Checks the given topology state for an atomic update to ensure that it's
5130 * valid. This includes checking whether there's enough bandwidth to support
5131 * the new VCPI allocations in the atomic update.
5132 *
5133 * Any atomic drivers supporting DP MST must make sure to call this after
5134 * checking the rest of their state in their
5135 * &drm_mode_config_funcs.atomic_check() callback.
5136 *
5137 * See also:
5138 * drm_dp_atomic_find_vcpi_slots()
5139 * drm_dp_atomic_release_vcpi_slots()
5140 *
5141 * Returns:
5142 *
5143 * 0 if the new state is valid, negative error code otherwise.
5144 */
5145int drm_dp_mst_atomic_check(struct drm_atomic_state *state)
5146{
5147	struct drm_dp_mst_topology_mgr *mgr;
5148	struct drm_dp_mst_topology_state *mst_state;
5149	int i, ret = 0;
5150
5151	for_each_new_mst_mgr_in_state(state, mgr, mst_state, i) {
5152		if (!mgr->mst_state)
5153			continue;
5154
5155		ret = drm_dp_mst_atomic_check_vcpi_alloc_limit(mgr, mst_state);
5156		if (ret)
5157			break;
5158
5159		mutex_lock(&mgr->lock);
5160		ret = drm_dp_mst_atomic_check_mstb_bw_limit(mgr->mst_primary,
5161							    mst_state);
5162		mutex_unlock(&mgr->lock);
5163		if (ret < 0)
5164			break;
5165		else
5166			ret = 0;
5167	}
5168
5169	return ret;
5170}
5171EXPORT_SYMBOL(drm_dp_mst_atomic_check);
5172
5173const struct drm_private_state_funcs drm_dp_mst_topology_state_funcs = {
5174	.atomic_duplicate_state = drm_dp_mst_duplicate_state,
5175	.atomic_destroy_state = drm_dp_mst_destroy_state,
5176};
5177EXPORT_SYMBOL(drm_dp_mst_topology_state_funcs);
5178
5179/**
5180 * drm_atomic_get_mst_topology_state: get MST topology state
5181 *
5182 * @state: global atomic state
5183 * @mgr: MST topology manager, also the private object in this case
5184 *
5185 * This function wraps drm_atomic_get_priv_obj_state() passing in the MST atomic
5186 * state vtable so that the private object state returned is that of a MST
5187 * topology object. Also, drm_atomic_get_private_obj_state() expects the caller
5188 * to care of the locking, so warn if don't hold the connection_mutex.
5189 *
5190 * RETURNS:
5191 *
5192 * The MST topology state or error pointer.
5193 */
5194struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
5195								    struct drm_dp_mst_topology_mgr *mgr)
5196{
5197	return to_dp_mst_topology_state(drm_atomic_get_private_obj_state(state, &mgr->base));
5198}
5199EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
5200
5201/**
5202 * drm_dp_mst_topology_mgr_init - initialise a topology manager
5203 * @mgr: manager struct to initialise
5204 * @dev: device providing this structure - for i2c addition.
5205 * @aux: DP helper aux channel to talk to this device
5206 * @max_dpcd_transaction_bytes: hw specific DPCD transaction limit
5207 * @max_payloads: maximum number of payloads this GPU can source
5208 * @conn_base_id: the connector object ID the MST device is connected to.
5209 *
5210 * Return 0 for success, or negative error code on failure
5211 */
5212int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
5213				 struct drm_device *dev, struct drm_dp_aux *aux,
5214				 int max_dpcd_transaction_bytes,
5215				 int max_payloads, int conn_base_id)
5216{
5217	struct drm_dp_mst_topology_state *mst_state;
5218
5219	mutex_init(&mgr->lock);
5220	mutex_init(&mgr->qlock);
5221	mutex_init(&mgr->payload_lock);
5222	mutex_init(&mgr->delayed_destroy_lock);
5223	mutex_init(&mgr->up_req_lock);
5224	mutex_init(&mgr->probe_lock);
5225#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
5226	mutex_init(&mgr->topology_ref_history_lock);
5227#endif
5228	INIT_LIST_HEAD(&mgr->tx_msg_downq);
5229	INIT_LIST_HEAD(&mgr->destroy_port_list);
5230	INIT_LIST_HEAD(&mgr->destroy_branch_device_list);
5231	INIT_LIST_HEAD(&mgr->up_req_list);
5232
5233	/*
5234	 * delayed_destroy_work will be queued on a dedicated WQ, so that any
5235	 * requeuing will be also flushed when deiniting the topology manager.
5236	 */
5237	mgr->delayed_destroy_wq = alloc_ordered_workqueue("drm_dp_mst_wq", 0);
5238	if (mgr->delayed_destroy_wq == NULL)
5239		return -ENOMEM;
5240
5241	INIT_WORK(&mgr->work, drm_dp_mst_link_probe_work);
5242	INIT_WORK(&mgr->tx_work, drm_dp_tx_work);
5243	INIT_WORK(&mgr->delayed_destroy_work, drm_dp_delayed_destroy_work);
5244	INIT_WORK(&mgr->up_req_work, drm_dp_mst_up_req_work);
5245	init_waitqueue_head(&mgr->tx_waitq);
5246	mgr->dev = dev;
5247	mgr->aux = aux;
5248	mgr->max_dpcd_transaction_bytes = max_dpcd_transaction_bytes;
5249	mgr->max_payloads = max_payloads;
5250	mgr->conn_base_id = conn_base_id;
5251	if (max_payloads + 1 > sizeof(mgr->payload_mask) * 8 ||
5252	    max_payloads + 1 > sizeof(mgr->vcpi_mask) * 8)
5253		return -EINVAL;
5254	mgr->payloads = kcalloc(max_payloads, sizeof(struct drm_dp_payload), GFP_KERNEL);
5255	if (!mgr->payloads)
5256		return -ENOMEM;
5257	mgr->proposed_vcpis = kcalloc(max_payloads, sizeof(struct drm_dp_vcpi *), GFP_KERNEL);
5258	if (!mgr->proposed_vcpis)
5259		return -ENOMEM;
5260	set_bit(0, &mgr->payload_mask);
5261
5262	mst_state = kzalloc(sizeof(*mst_state), GFP_KERNEL);
5263	if (mst_state == NULL)
5264		return -ENOMEM;
5265
5266	mst_state->mgr = mgr;
5267	INIT_LIST_HEAD(&mst_state->vcpis);
5268
5269	drm_atomic_private_obj_init(dev, &mgr->base,
5270				    &mst_state->base,
5271				    &drm_dp_mst_topology_state_funcs);
5272
5273	return 0;
5274}
5275EXPORT_SYMBOL(drm_dp_mst_topology_mgr_init);
5276
5277/**
5278 * drm_dp_mst_topology_mgr_destroy() - destroy topology manager.
5279 * @mgr: manager to destroy
5280 */
5281void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr)
5282{
5283	drm_dp_mst_topology_mgr_set_mst(mgr, false);
5284	flush_work(&mgr->work);
5285	/* The following will also drain any requeued work on the WQ. */
5286	if (mgr->delayed_destroy_wq) {
5287		destroy_workqueue(mgr->delayed_destroy_wq);
5288		mgr->delayed_destroy_wq = NULL;
5289	}
5290	mutex_lock(&mgr->payload_lock);
5291	kfree(mgr->payloads);
5292	mgr->payloads = NULL;
5293	kfree(mgr->proposed_vcpis);
5294	mgr->proposed_vcpis = NULL;
5295	mutex_unlock(&mgr->payload_lock);
5296	mgr->dev = NULL;
5297	mgr->aux = NULL;
5298	drm_atomic_private_obj_fini(&mgr->base);
5299	mgr->funcs = NULL;
5300
5301	mutex_destroy(&mgr->delayed_destroy_lock);
5302	mutex_destroy(&mgr->payload_lock);
5303	mutex_destroy(&mgr->qlock);
5304	mutex_destroy(&mgr->lock);
5305	mutex_destroy(&mgr->up_req_lock);
5306	mutex_destroy(&mgr->probe_lock);
5307#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
5308	mutex_destroy(&mgr->topology_ref_history_lock);
5309#endif
5310}
5311EXPORT_SYMBOL(drm_dp_mst_topology_mgr_destroy);
5312
5313static bool remote_i2c_read_ok(const struct i2c_msg msgs[], int num)
5314{
5315	int i;
5316
5317	if (num - 1 > DP_REMOTE_I2C_READ_MAX_TRANSACTIONS)
5318		return false;
5319
5320	for (i = 0; i < num - 1; i++) {
5321		if (msgs[i].flags & I2C_M_RD ||
5322		    msgs[i].len > 0xff)
5323			return false;
5324	}
5325
5326	return msgs[num - 1].flags & I2C_M_RD &&
5327		msgs[num - 1].len <= 0xff;
5328}
5329
5330/* I2C device */
5331static int drm_dp_mst_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
5332			       int num)
5333{
5334	struct drm_dp_aux *aux = adapter->algo_data;
5335	struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port, aux);
5336	struct drm_dp_mst_branch *mstb;
5337	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
5338	unsigned int i;
5339	struct drm_dp_sideband_msg_req_body msg;
5340	struct drm_dp_sideband_msg_tx *txmsg = NULL;
5341	int ret;
5342
5343	mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
5344	if (!mstb)
5345		return -EREMOTEIO;
5346
5347	if (!remote_i2c_read_ok(msgs, num)) {
5348		DRM_DEBUG_KMS("Unsupported I2C transaction for MST device\n");
5349		ret = -EIO;
5350		goto out;
5351	}
5352
5353	memset(&msg, 0, sizeof(msg));
5354	msg.req_type = DP_REMOTE_I2C_READ;
5355	msg.u.i2c_read.num_transactions = num - 1;
5356	msg.u.i2c_read.port_number = port->port_num;
5357	for (i = 0; i < num - 1; i++) {
5358		msg.u.i2c_read.transactions[i].i2c_dev_id = msgs[i].addr;
5359		msg.u.i2c_read.transactions[i].num_bytes = msgs[i].len;
5360		msg.u.i2c_read.transactions[i].bytes = msgs[i].buf;
5361		msg.u.i2c_read.transactions[i].no_stop_bit = !(msgs[i].flags & I2C_M_STOP);
5362	}
5363	msg.u.i2c_read.read_i2c_device_id = msgs[num - 1].addr;
5364	msg.u.i2c_read.num_bytes_read = msgs[num - 1].len;
5365
5366	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
5367	if (!txmsg) {
5368		ret = -ENOMEM;
5369		goto out;
5370	}
5371
5372	txmsg->dst = mstb;
5373	drm_dp_encode_sideband_req(&msg, txmsg);
5374
5375	drm_dp_queue_down_tx(mgr, txmsg);
5376
5377	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
5378	if (ret > 0) {
5379
5380		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
5381			ret = -EREMOTEIO;
5382			goto out;
5383		}
5384		if (txmsg->reply.u.remote_i2c_read_ack.num_bytes != msgs[num - 1].len) {
5385			ret = -EIO;
5386			goto out;
5387		}
5388		memcpy(msgs[num - 1].buf, txmsg->reply.u.remote_i2c_read_ack.bytes, msgs[num - 1].len);
5389		ret = num;
5390	}
5391out:
5392	kfree(txmsg);
5393	drm_dp_mst_topology_put_mstb(mstb);
5394	return ret;
5395}
5396
5397static u32 drm_dp_mst_i2c_functionality(struct i2c_adapter *adapter)
5398{
5399	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
5400	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
5401	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
5402	       I2C_FUNC_10BIT_ADDR;
5403}
5404
5405static const struct i2c_algorithm drm_dp_mst_i2c_algo = {
5406	.functionality = drm_dp_mst_i2c_functionality,
5407	.master_xfer = drm_dp_mst_i2c_xfer,
5408};
5409
5410/**
5411 * drm_dp_mst_register_i2c_bus() - register an I2C adapter for I2C-over-AUX
5412 * @port: The port to add the I2C bus on
5413 *
5414 * Returns 0 on success or a negative error code on failure.
5415 */
5416static int drm_dp_mst_register_i2c_bus(struct drm_dp_mst_port *port)
5417{
5418	struct drm_dp_aux *aux = &port->aux;
5419	struct device *parent_dev = port->mgr->dev->dev;
5420
5421	aux->ddc.algo = &drm_dp_mst_i2c_algo;
5422	aux->ddc.algo_data = aux;
5423	aux->ddc.retries = 3;
5424
5425	aux->ddc.class = I2C_CLASS_DDC;
5426	aux->ddc.owner = THIS_MODULE;
5427	/* FIXME: set the kdev of the port's connector as parent */
5428	aux->ddc.dev.parent = parent_dev;
5429	aux->ddc.dev.of_node = parent_dev->of_node;
5430
5431	strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(parent_dev),
5432		sizeof(aux->ddc.name));
5433
5434	return i2c_add_adapter(&aux->ddc);
5435}
5436
5437/**
5438 * drm_dp_mst_unregister_i2c_bus() - unregister an I2C-over-AUX adapter
5439 * @port: The port to remove the I2C bus from
5440 */
5441static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_mst_port *port)
5442{
5443	i2c_del_adapter(&port->aux.ddc);
5444}
5445
5446/**
5447 * drm_dp_mst_is_virtual_dpcd() - Is the given port a virtual DP Peer Device
5448 * @port: The port to check
5449 *
5450 * A single physical MST hub object can be represented in the topology
5451 * by multiple branches, with virtual ports between those branches.
5452 *
5453 * As of DP1.4, An MST hub with internal (virtual) ports must expose
5454 * certain DPCD registers over those ports. See sections 2.6.1.1.1
5455 * and 2.6.1.1.2 of Display Port specification v1.4 for details.
5456 *
5457 * May acquire mgr->lock
5458 *
5459 * Returns:
5460 * true if the port is a virtual DP peer device, false otherwise
5461 */
5462static bool drm_dp_mst_is_virtual_dpcd(struct drm_dp_mst_port *port)
5463{
5464	struct drm_dp_mst_port *downstream_port;
5465
5466	if (!port || port->dpcd_rev < DP_DPCD_REV_14)
5467		return false;
5468
5469	/* Virtual DP Sink (Internal Display Panel) */
5470	if (port->port_num >= 8)
5471		return true;
5472
5473	/* DP-to-HDMI Protocol Converter */
5474	if (port->pdt == DP_PEER_DEVICE_DP_LEGACY_CONV &&
5475	    !port->mcs &&
5476	    port->ldps)
5477		return true;
5478
5479	/* DP-to-DP */
5480	mutex_lock(&port->mgr->lock);
5481	if (port->pdt == DP_PEER_DEVICE_MST_BRANCHING &&
5482	    port->mstb &&
5483	    port->mstb->num_ports == 2) {
5484		list_for_each_entry(downstream_port, &port->mstb->ports, next) {
5485			if (downstream_port->pdt == DP_PEER_DEVICE_SST_SINK &&
5486			    !downstream_port->input) {
5487				mutex_unlock(&port->mgr->lock);
5488				return true;
5489			}
5490		}
5491	}
5492	mutex_unlock(&port->mgr->lock);
5493
5494	return false;
5495}
5496
5497/**
5498 * drm_dp_mst_dsc_aux_for_port() - Find the correct aux for DSC
5499 * @port: The port to check. A leaf of the MST tree with an attached display.
5500 *
5501 * Depending on the situation, DSC may be enabled via the endpoint aux,
5502 * the immediately upstream aux, or the connector's physical aux.
5503 *
5504 * This is both the correct aux to read DSC_CAPABILITY and the
5505 * correct aux to write DSC_ENABLED.
5506 *
5507 * This operation can be expensive (up to four aux reads), so
5508 * the caller should cache the return.
5509 *
5510 * Returns:
5511 * NULL if DSC cannot be enabled on this port, otherwise the aux device
5512 */
5513struct drm_dp_aux *drm_dp_mst_dsc_aux_for_port(struct drm_dp_mst_port *port)
5514{
5515	struct drm_dp_mst_port *immediate_upstream_port;
5516	struct drm_dp_mst_port *fec_port;
5517	struct drm_dp_desc desc = {};
5518	u8 endpoint_fec;
5519	u8 endpoint_dsc;
5520
5521	if (!port)
5522		return NULL;
5523
5524	if (port->parent->port_parent)
5525		immediate_upstream_port = port->parent->port_parent;
5526	else
5527		immediate_upstream_port = NULL;
5528
5529	fec_port = immediate_upstream_port;
5530	while (fec_port) {
5531		/*
5532		 * Each physical link (i.e. not a virtual port) between the
5533		 * output and the primary device must support FEC
5534		 */
5535		if (!drm_dp_mst_is_virtual_dpcd(fec_port) &&
5536		    !fec_port->fec_capable)
5537			return NULL;
5538
5539		fec_port = fec_port->parent->port_parent;
5540	}
5541
5542	/* DP-to-DP peer device */
5543	if (drm_dp_mst_is_virtual_dpcd(immediate_upstream_port)) {
5544		u8 upstream_dsc;
5545
5546		if (drm_dp_dpcd_read(&port->aux,
5547				     DP_DSC_SUPPORT, &endpoint_dsc, 1) != 1)
5548			return NULL;
5549		if (drm_dp_dpcd_read(&port->aux,
5550				     DP_FEC_CAPABILITY, &endpoint_fec, 1) != 1)
5551			return NULL;
5552		if (drm_dp_dpcd_read(&immediate_upstream_port->aux,
5553				     DP_DSC_SUPPORT, &upstream_dsc, 1) != 1)
5554			return NULL;
5555
5556		/* Enpoint decompression with DP-to-DP peer device */
5557		if ((endpoint_dsc & DP_DSC_DECOMPRESSION_IS_SUPPORTED) &&
5558		    (endpoint_fec & DP_FEC_CAPABLE) &&
5559		    (upstream_dsc & 0x2) /* DSC passthrough */)
5560			return &port->aux;
5561
5562		/* Virtual DPCD decompression with DP-to-DP peer device */
5563		return &immediate_upstream_port->aux;
5564	}
5565
5566	/* Virtual DPCD decompression with DP-to-HDMI or Virtual DP Sink */
5567	if (drm_dp_mst_is_virtual_dpcd(port))
5568		return &port->aux;
5569
5570	/*
5571	 * Synaptics quirk
5572	 * Applies to ports for which:
5573	 * - Physical aux has Synaptics OUI
5574	 * - DPv1.4 or higher
5575	 * - Port is on primary branch device
5576	 * - Not a VGA adapter (DP_DWN_STRM_PORT_TYPE_ANALOG)
5577	 */
5578	if (drm_dp_read_desc(port->mgr->aux, &desc, true))
5579		return NULL;
5580
5581	if (drm_dp_has_quirk(&desc, 0,
5582			     DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) &&
5583	    port->mgr->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14 &&
5584	    port->parent == port->mgr->mst_primary) {
5585		u8 downstreamport;
5586
5587		if (drm_dp_dpcd_read(&port->aux, DP_DOWNSTREAMPORT_PRESENT,
5588				     &downstreamport, 1) < 0)
5589			return NULL;
5590
5591		if ((downstreamport & DP_DWN_STRM_PORT_PRESENT) &&
5592		   ((downstreamport & DP_DWN_STRM_PORT_TYPE_MASK)
5593		     != DP_DWN_STRM_PORT_TYPE_ANALOG))
5594			return port->mgr->aux;
5595	}
5596
5597	/*
5598	 * The check below verifies if the MST sink
5599	 * connected to the GPU is capable of DSC -
5600	 * therefore the endpoint needs to be
5601	 * both DSC and FEC capable.
5602	 */
5603	if (drm_dp_dpcd_read(&port->aux,
5604	   DP_DSC_SUPPORT, &endpoint_dsc, 1) != 1)
5605		return NULL;
5606	if (drm_dp_dpcd_read(&port->aux,
5607	   DP_FEC_CAPABILITY, &endpoint_fec, 1) != 1)
5608		return NULL;
5609	if ((endpoint_dsc & DP_DSC_DECOMPRESSION_IS_SUPPORTED) &&
5610	   (endpoint_fec & DP_FEC_CAPABLE))
5611		return &port->aux;
5612
5613	return NULL;
5614}
5615EXPORT_SYMBOL(drm_dp_mst_dsc_aux_for_port);