1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Copyright (C) 2004 Hollis Blanchard <hollisb@us.ibm.com>, IBM
   4 */
   5
   6/* Host Virtual Serial Interface (HVSI) is a protocol between the hosted OS
   7 * and the service processor on IBM pSeries servers. On these servers, there
   8 * are no serial ports under the OS's control, and sometimes there is no other
   9 * console available either. However, the service processor has two standard
  10 * serial ports, so this over-complicated protocol allows the OS to control
  11 * those ports by proxy.
  12 *
  13 * Besides data, the procotol supports the reading/writing of the serial
  14 * port's DTR line, and the reading of the CD line. This is to allow the OS to
  15 * control a modem attached to the service processor's serial port. Note that
  16 * the OS cannot change the speed of the port through this protocol.
  17 */
  18
  19#undef DEBUG
  20
  21#include <linux/console.h>
  22#include <linux/ctype.h>
  23#include <linux/delay.h>
  24#include <linux/init.h>
  25#include <linux/interrupt.h>
  26#include <linux/module.h>
  27#include <linux/major.h>
  28#include <linux/kernel.h>
  29#include <linux/of_irq.h>
  30#include <linux/spinlock.h>
  31#include <linux/sysrq.h>
  32#include <linux/tty.h>
  33#include <linux/tty_flip.h>
  34#include <asm/hvcall.h>
  35#include <asm/hvconsole.h>
 
  36#include <linux/uaccess.h>
  37#include <asm/vio.h>
  38#include <asm/param.h>
  39#include <asm/hvsi.h>
  40
  41#define HVSI_MAJOR	229
  42#define HVSI_MINOR	128
  43#define MAX_NR_HVSI_CONSOLES 4
  44
  45#define HVSI_TIMEOUT (5*HZ)
  46#define HVSI_VERSION 1
  47#define HVSI_MAX_PACKET 256
  48#define HVSI_MAX_READ 16
  49#define HVSI_MAX_OUTGOING_DATA 12
  50#define N_OUTBUF 12
  51
  52/*
  53 * we pass data via two 8-byte registers, so we would like our char arrays
  54 * properly aligned for those loads.
  55 */
  56#define __ALIGNED__	__attribute__((__aligned__(sizeof(long))))
  57
  58struct hvsi_struct {
  59	struct tty_port port;
  60	struct delayed_work writer;
  61	struct work_struct handshaker;
  62	wait_queue_head_t emptyq; /* woken when outbuf is emptied */
  63	wait_queue_head_t stateq; /* woken when HVSI state changes */
  64	spinlock_t lock;
  65	int index;
  66	uint8_t throttle_buf[128];
  67	uint8_t outbuf[N_OUTBUF]; /* to implement write_room and chars_in_buffer */
  68	/* inbuf is for packet reassembly. leave a little room for leftovers. */
  69	uint8_t inbuf[HVSI_MAX_PACKET + HVSI_MAX_READ];
  70	uint8_t *inbuf_end;
  71	int n_throttle;
  72	int n_outbuf;
  73	uint32_t vtermno;
  74	uint32_t virq;
  75	atomic_t seqno; /* HVSI packet sequence number */
  76	uint16_t mctrl;
  77	uint8_t state;  /* HVSI protocol state */
  78	uint8_t flags;
  79#ifdef CONFIG_MAGIC_SYSRQ
  80	uint8_t sysrq;
  81#endif /* CONFIG_MAGIC_SYSRQ */
  82};
  83static struct hvsi_struct hvsi_ports[MAX_NR_HVSI_CONSOLES];
  84
  85static struct tty_driver *hvsi_driver;
  86static int hvsi_count;
  87static int (*hvsi_wait)(struct hvsi_struct *hp, int state);
  88
  89enum HVSI_PROTOCOL_STATE {
  90	HVSI_CLOSED,
  91	HVSI_WAIT_FOR_VER_RESPONSE,
  92	HVSI_WAIT_FOR_VER_QUERY,
  93	HVSI_OPEN,
  94	HVSI_WAIT_FOR_MCTRL_RESPONSE,
  95	HVSI_FSP_DIED,
  96};
  97#define HVSI_CONSOLE 0x1
  98
  99static inline int is_console(struct hvsi_struct *hp)
 100{
 101	return hp->flags & HVSI_CONSOLE;
 102}
 103
 104static inline int is_open(struct hvsi_struct *hp)
 105{
 106	/* if we're waiting for an mctrl then we're already open */
 107	return (hp->state == HVSI_OPEN)
 108			|| (hp->state == HVSI_WAIT_FOR_MCTRL_RESPONSE);
 109}
 110
 111static inline void print_state(struct hvsi_struct *hp)
 112{
 113#ifdef DEBUG
 114	static const char *state_names[] = {
 115		"HVSI_CLOSED",
 116		"HVSI_WAIT_FOR_VER_RESPONSE",
 117		"HVSI_WAIT_FOR_VER_QUERY",
 118		"HVSI_OPEN",
 119		"HVSI_WAIT_FOR_MCTRL_RESPONSE",
 120		"HVSI_FSP_DIED",
 121	};
 122	const char *name = (hp->state < ARRAY_SIZE(state_names))
 123		? state_names[hp->state] : "UNKNOWN";
 124
 125	pr_debug("hvsi%i: state = %s\n", hp->index, name);
 126#endif /* DEBUG */
 127}
 128
 129static inline void __set_state(struct hvsi_struct *hp, int state)
 130{
 131	hp->state = state;
 132	print_state(hp);
 133	wake_up_all(&hp->stateq);
 134}
 135
 136static inline void set_state(struct hvsi_struct *hp, int state)
 137{
 138	unsigned long flags;
 139
 140	spin_lock_irqsave(&hp->lock, flags);
 141	__set_state(hp, state);
 142	spin_unlock_irqrestore(&hp->lock, flags);
 143}
 144
 145static inline int len_packet(const uint8_t *packet)
 146{
 147	return (int)((struct hvsi_header *)packet)->len;
 148}
 149
 150static inline int is_header(const uint8_t *packet)
 151{
 152	struct hvsi_header *header = (struct hvsi_header *)packet;
 153	return header->type >= VS_QUERY_RESPONSE_PACKET_HEADER;
 154}
 155
 156static inline int got_packet(const struct hvsi_struct *hp, uint8_t *packet)
 157{
 158	if (hp->inbuf_end < packet + sizeof(struct hvsi_header))
 159		return 0; /* don't even have the packet header */
 160
 161	if (hp->inbuf_end < (packet + len_packet(packet)))
 162		return 0; /* don't have the rest of the packet */
 163
 164	return 1;
 165}
 166
 167/* shift remaining bytes in packetbuf down */
 168static void compact_inbuf(struct hvsi_struct *hp, uint8_t *read_to)
 169{
 170	int remaining = (int)(hp->inbuf_end - read_to);
 171
 172	pr_debug("%s: %i chars remain\n", __func__, remaining);
 173
 174	if (read_to != hp->inbuf)
 175		memmove(hp->inbuf, read_to, remaining);
 176
 177	hp->inbuf_end = hp->inbuf + remaining;
 178}
 179
 180#ifdef DEBUG
 181#define dbg_dump_packet(packet) dump_packet(packet)
 182#define dbg_dump_hex(data, len) dump_hex(data, len)
 183#else
 184#define dbg_dump_packet(packet) do { } while (0)
 185#define dbg_dump_hex(data, len) do { } while (0)
 186#endif
 187
 188static void dump_hex(const uint8_t *data, int len)
 189{
 190	int i;
 191
 192	printk("    ");
 193	for (i=0; i < len; i++)
 194		printk("%.2x", data[i]);
 195
 196	printk("\n    ");
 197	for (i=0; i < len; i++) {
 198		if (isprint(data[i]))
 199			printk("%c", data[i]);
 200		else
 201			printk(".");
 202	}
 203	printk("\n");
 204}
 205
 206static void dump_packet(uint8_t *packet)
 207{
 208	struct hvsi_header *header = (struct hvsi_header *)packet;
 209
 210	printk("type 0x%x, len %i, seqno %i:\n", header->type, header->len,
 211			header->seqno);
 212
 213	dump_hex(packet, header->len);
 214}
 215
 216static int hvsi_read(struct hvsi_struct *hp, char *buf, int count)
 217{
 218	unsigned long got;
 219
 220	got = hvc_get_chars(hp->vtermno, buf, count);
 221
 222	return got;
 223}
 224
 225static void hvsi_recv_control(struct hvsi_struct *hp, uint8_t *packet,
 226	struct tty_struct *tty, struct hvsi_struct **to_handshake)
 227{
 228	struct hvsi_control *header = (struct hvsi_control *)packet;
 229
 230	switch (be16_to_cpu(header->verb)) {
 231		case VSV_MODEM_CTL_UPDATE:
 232			if ((be32_to_cpu(header->word) & HVSI_TSCD) == 0) {
 233				/* CD went away; no more connection */
 234				pr_debug("hvsi%i: CD dropped\n", hp->index);
 235				hp->mctrl &= TIOCM_CD;
 236				if (tty && !C_CLOCAL(tty))
 237					tty_hangup(tty);
 238			}
 239			break;
 240		case VSV_CLOSE_PROTOCOL:
 241			pr_debug("hvsi%i: service processor came back\n", hp->index);
 242			if (hp->state != HVSI_CLOSED) {
 243				*to_handshake = hp;
 244			}
 245			break;
 246		default:
 247			printk(KERN_WARNING "hvsi%i: unknown HVSI control packet: ",
 248				hp->index);
 249			dump_packet(packet);
 250			break;
 251	}
 252}
 253
 254static void hvsi_recv_response(struct hvsi_struct *hp, uint8_t *packet)
 255{
 256	struct hvsi_query_response *resp = (struct hvsi_query_response *)packet;
 257	uint32_t mctrl_word;
 258
 259	switch (hp->state) {
 260		case HVSI_WAIT_FOR_VER_RESPONSE:
 261			__set_state(hp, HVSI_WAIT_FOR_VER_QUERY);
 262			break;
 263		case HVSI_WAIT_FOR_MCTRL_RESPONSE:
 264			hp->mctrl = 0;
 265			mctrl_word = be32_to_cpu(resp->u.mctrl_word);
 266			if (mctrl_word & HVSI_TSDTR)
 267				hp->mctrl |= TIOCM_DTR;
 268			if (mctrl_word & HVSI_TSCD)
 269				hp->mctrl |= TIOCM_CD;
 270			__set_state(hp, HVSI_OPEN);
 271			break;
 272		default:
 273			printk(KERN_ERR "hvsi%i: unexpected query response: ", hp->index);
 274			dump_packet(packet);
 275			break;
 276	}
 277}
 278
 279/* respond to service processor's version query */
 280static int hvsi_version_respond(struct hvsi_struct *hp, uint16_t query_seqno)
 281{
 282	struct hvsi_query_response packet __ALIGNED__;
 283	int wrote;
 284
 285	packet.hdr.type = VS_QUERY_RESPONSE_PACKET_HEADER;
 286	packet.hdr.len = sizeof(struct hvsi_query_response);
 287	packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
 288	packet.verb = cpu_to_be16(VSV_SEND_VERSION_NUMBER);
 289	packet.u.version = HVSI_VERSION;
 290	packet.query_seqno = cpu_to_be16(query_seqno+1);
 291
 292	pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
 293	dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
 294
 295	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
 296	if (wrote != packet.hdr.len) {
 297		printk(KERN_ERR "hvsi%i: couldn't send query response!\n",
 298			hp->index);
 299		return -EIO;
 300	}
 301
 302	return 0;
 303}
 304
 305static void hvsi_recv_query(struct hvsi_struct *hp, uint8_t *packet)
 306{
 307	struct hvsi_query *query = (struct hvsi_query *)packet;
 308
 309	switch (hp->state) {
 310		case HVSI_WAIT_FOR_VER_QUERY:
 311			hvsi_version_respond(hp, be16_to_cpu(query->hdr.seqno));
 312			__set_state(hp, HVSI_OPEN);
 313			break;
 314		default:
 315			printk(KERN_ERR "hvsi%i: unexpected query: ", hp->index);
 316			dump_packet(packet);
 317			break;
 318	}
 319}
 320
 321static void hvsi_insert_chars(struct hvsi_struct *hp, const char *buf, int len)
 322{
 323	int i;
 324
 325	for (i=0; i < len; i++) {
 326		char c = buf[i];
 327#ifdef CONFIG_MAGIC_SYSRQ
 328		if (c == '\0') {
 329			hp->sysrq = 1;
 330			continue;
 331		} else if (hp->sysrq) {
 332			handle_sysrq(c);
 333			hp->sysrq = 0;
 334			continue;
 335		}
 336#endif /* CONFIG_MAGIC_SYSRQ */
 337		tty_insert_flip_char(&hp->port, c, 0);
 338	}
 339}
 340
 341/*
 342 * We could get 252 bytes of data at once here. But the tty layer only
 343 * throttles us at TTY_THRESHOLD_THROTTLE (128) bytes, so we could overflow
 344 * it. Accordingly we won't send more than 128 bytes at a time to the flip
 345 * buffer, which will give the tty buffer a chance to throttle us. Should the
 346 * value of TTY_THRESHOLD_THROTTLE change in n_tty.c, this code should be
 347 * revisited.
 348 */
 349#define TTY_THRESHOLD_THROTTLE 128
 350static bool hvsi_recv_data(struct hvsi_struct *hp, const uint8_t *packet)
 351{
 352	const struct hvsi_header *header = (const struct hvsi_header *)packet;
 353	const uint8_t *data = packet + sizeof(struct hvsi_header);
 354	int datalen = header->len - sizeof(struct hvsi_header);
 355	int overflow = datalen - TTY_THRESHOLD_THROTTLE;
 356
 357	pr_debug("queueing %i chars '%.*s'\n", datalen, datalen, data);
 358
 359	if (datalen == 0)
 360		return false;
 361
 362	if (overflow > 0) {
 363		pr_debug("%s: got >TTY_THRESHOLD_THROTTLE bytes\n", __func__);
 364		datalen = TTY_THRESHOLD_THROTTLE;
 365	}
 366
 367	hvsi_insert_chars(hp, data, datalen);
 368
 369	if (overflow > 0) {
 370		/*
 371		 * we still have more data to deliver, so we need to save off the
 372		 * overflow and send it later
 373		 */
 374		pr_debug("%s: deferring overflow\n", __func__);
 375		memcpy(hp->throttle_buf, data + TTY_THRESHOLD_THROTTLE, overflow);
 376		hp->n_throttle = overflow;
 377	}
 378
 379	return true;
 380}
 381
 382/*
 383 * Returns true/false indicating data successfully read from hypervisor.
 384 * Used both to get packets for tty connections and to advance the state
 385 * machine during console handshaking (in which case tty = NULL and we ignore
 386 * incoming data).
 387 */
 388static int hvsi_load_chunk(struct hvsi_struct *hp, struct tty_struct *tty,
 389		struct hvsi_struct **handshake)
 390{
 391	uint8_t *packet = hp->inbuf;
 392	int chunklen;
 393	bool flip = false;
 394
 395	*handshake = NULL;
 396
 397	chunklen = hvsi_read(hp, hp->inbuf_end, HVSI_MAX_READ);
 398	if (chunklen == 0) {
 399		pr_debug("%s: 0-length read\n", __func__);
 400		return 0;
 401	}
 402
 403	pr_debug("%s: got %i bytes\n", __func__, chunklen);
 404	dbg_dump_hex(hp->inbuf_end, chunklen);
 405
 406	hp->inbuf_end += chunklen;
 407
 408	/* handle all completed packets */
 409	while ((packet < hp->inbuf_end) && got_packet(hp, packet)) {
 410		struct hvsi_header *header = (struct hvsi_header *)packet;
 411
 412		if (!is_header(packet)) {
 413			printk(KERN_ERR "hvsi%i: got malformed packet\n", hp->index);
 414			/* skip bytes until we find a header or run out of data */
 415			while ((packet < hp->inbuf_end) && (!is_header(packet)))
 416				packet++;
 417			continue;
 418		}
 419
 420		pr_debug("%s: handling %i-byte packet\n", __func__,
 421				len_packet(packet));
 422		dbg_dump_packet(packet);
 423
 424		switch (header->type) {
 425			case VS_DATA_PACKET_HEADER:
 426				if (!is_open(hp))
 427					break;
 428				flip = hvsi_recv_data(hp, packet);
 429				break;
 430			case VS_CONTROL_PACKET_HEADER:
 431				hvsi_recv_control(hp, packet, tty, handshake);
 432				break;
 433			case VS_QUERY_RESPONSE_PACKET_HEADER:
 434				hvsi_recv_response(hp, packet);
 435				break;
 436			case VS_QUERY_PACKET_HEADER:
 437				hvsi_recv_query(hp, packet);
 438				break;
 439			default:
 440				printk(KERN_ERR "hvsi%i: unknown HVSI packet type 0x%x\n",
 441						hp->index, header->type);
 442				dump_packet(packet);
 443				break;
 444		}
 445
 446		packet += len_packet(packet);
 447
 448		if (*handshake) {
 449			pr_debug("%s: handshake\n", __func__);
 450			break;
 451		}
 452	}
 453
 454	compact_inbuf(hp, packet);
 455
 456	if (flip)
 457		tty_flip_buffer_push(&hp->port);
 458
 459	return 1;
 460}
 461
 462static void hvsi_send_overflow(struct hvsi_struct *hp)
 463{
 464	pr_debug("%s: delivering %i bytes overflow\n", __func__,
 465			hp->n_throttle);
 466
 467	hvsi_insert_chars(hp, hp->throttle_buf, hp->n_throttle);
 468	hp->n_throttle = 0;
 469}
 470
 471/*
 472 * must get all pending data because we only get an irq on empty->non-empty
 473 * transition
 474 */
 475static irqreturn_t hvsi_interrupt(int irq, void *arg)
 476{
 477	struct hvsi_struct *hp = (struct hvsi_struct *)arg;
 478	struct hvsi_struct *handshake;
 479	struct tty_struct *tty;
 480	unsigned long flags;
 481	int again = 1;
 482
 483	pr_debug("%s\n", __func__);
 484
 485	tty = tty_port_tty_get(&hp->port);
 486
 487	while (again) {
 488		spin_lock_irqsave(&hp->lock, flags);
 489		again = hvsi_load_chunk(hp, tty, &handshake);
 490		spin_unlock_irqrestore(&hp->lock, flags);
 491
 492		if (handshake) {
 493			pr_debug("hvsi%i: attempting re-handshake\n", handshake->index);
 494			schedule_work(&handshake->handshaker);
 495		}
 496	}
 497
 498	spin_lock_irqsave(&hp->lock, flags);
 499	if (tty && hp->n_throttle && !tty_throttled(tty)) {
 500		/* we weren't hung up and we weren't throttled, so we can
 501		 * deliver the rest now */
 502		hvsi_send_overflow(hp);
 503		tty_flip_buffer_push(&hp->port);
 504	}
 505	spin_unlock_irqrestore(&hp->lock, flags);
 506
 507	tty_kref_put(tty);
 508
 509	return IRQ_HANDLED;
 510}
 511
 512/* for boot console, before the irq handler is running */
 513static int __init poll_for_state(struct hvsi_struct *hp, int state)
 514{
 515	unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;
 516
 517	for (;;) {
 518		hvsi_interrupt(hp->virq, (void *)hp); /* get pending data */
 519
 520		if (hp->state == state)
 521			return 0;
 522
 523		mdelay(5);
 524		if (time_after(jiffies, end_jiffies))
 525			return -EIO;
 526	}
 527}
 528
 529/* wait for irq handler to change our state */
 530static int wait_for_state(struct hvsi_struct *hp, int state)
 531{
 532	int ret = 0;
 533
 534	if (!wait_event_timeout(hp->stateq, (hp->state == state), HVSI_TIMEOUT))
 535		ret = -EIO;
 536
 537	return ret;
 538}
 539
 540static int hvsi_query(struct hvsi_struct *hp, uint16_t verb)
 541{
 542	struct hvsi_query packet __ALIGNED__;
 543	int wrote;
 544
 545	packet.hdr.type = VS_QUERY_PACKET_HEADER;
 546	packet.hdr.len = sizeof(struct hvsi_query);
 547	packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
 548	packet.verb = cpu_to_be16(verb);
 549
 550	pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
 551	dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
 552
 553	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
 554	if (wrote != packet.hdr.len) {
 555		printk(KERN_ERR "hvsi%i: couldn't send query (%i)!\n", hp->index,
 556			wrote);
 557		return -EIO;
 558	}
 559
 560	return 0;
 561}
 562
 563static int hvsi_get_mctrl(struct hvsi_struct *hp)
 564{
 565	int ret;
 566
 567	set_state(hp, HVSI_WAIT_FOR_MCTRL_RESPONSE);
 568	hvsi_query(hp, VSV_SEND_MODEM_CTL_STATUS);
 569
 570	ret = hvsi_wait(hp, HVSI_OPEN);
 571	if (ret < 0) {
 572		printk(KERN_ERR "hvsi%i: didn't get modem flags\n", hp->index);
 573		set_state(hp, HVSI_OPEN);
 574		return ret;
 575	}
 576
 577	pr_debug("%s: mctrl 0x%x\n", __func__, hp->mctrl);
 578
 579	return 0;
 580}
 581
 582/* note that we can only set DTR */
 583static int hvsi_set_mctrl(struct hvsi_struct *hp, uint16_t mctrl)
 584{
 585	struct hvsi_control packet __ALIGNED__;
 586	int wrote;
 587
 588	packet.hdr.type = VS_CONTROL_PACKET_HEADER;
 589	packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
 590	packet.hdr.len = sizeof(struct hvsi_control);
 591	packet.verb = cpu_to_be16(VSV_SET_MODEM_CTL);
 592	packet.mask = cpu_to_be32(HVSI_TSDTR);
 593
 594	if (mctrl & TIOCM_DTR)
 595		packet.word = cpu_to_be32(HVSI_TSDTR);
 596
 597	pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
 598	dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
 599
 600	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
 601	if (wrote != packet.hdr.len) {
 602		printk(KERN_ERR "hvsi%i: couldn't set DTR!\n", hp->index);
 603		return -EIO;
 604	}
 605
 606	return 0;
 607}
 608
 609static void hvsi_drain_input(struct hvsi_struct *hp)
 610{
 611	uint8_t buf[HVSI_MAX_READ] __ALIGNED__;
 612	unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;
 613
 614	while (time_before(end_jiffies, jiffies))
 615		if (0 == hvsi_read(hp, buf, HVSI_MAX_READ))
 616			break;
 617}
 618
 619static int hvsi_handshake(struct hvsi_struct *hp)
 620{
 621	int ret;
 622
 623	/*
 624	 * We could have a CLOSE or other data waiting for us before we even try
 625	 * to open; try to throw it all away so we don't get confused. (CLOSE
 626	 * is the first message sent up the pipe when the FSP comes online. We
 627	 * need to distinguish between "it came up a while ago and we're the first
 628	 * user" and "it was just reset before it saw our handshake packet".)
 629	 */
 630	hvsi_drain_input(hp);
 631
 632	set_state(hp, HVSI_WAIT_FOR_VER_RESPONSE);
 633	ret = hvsi_query(hp, VSV_SEND_VERSION_NUMBER);
 634	if (ret < 0) {
 635		printk(KERN_ERR "hvsi%i: couldn't send version query\n", hp->index);
 636		return ret;
 637	}
 638
 639	ret = hvsi_wait(hp, HVSI_OPEN);
 640	if (ret < 0)
 641		return ret;
 642
 643	return 0;
 644}
 645
 646static void hvsi_handshaker(struct work_struct *work)
 647{
 648	struct hvsi_struct *hp =
 649		container_of(work, struct hvsi_struct, handshaker);
 650
 651	if (hvsi_handshake(hp) >= 0)
 652		return;
 653
 654	printk(KERN_ERR "hvsi%i: re-handshaking failed\n", hp->index);
 655	if (is_console(hp)) {
 656		/*
 657		 * ttys will re-attempt the handshake via hvsi_open, but
 658		 * the console will not.
 659		 */
 660		printk(KERN_ERR "hvsi%i: lost console!\n", hp->index);
 661	}
 662}
 663
 664static int hvsi_put_chars(struct hvsi_struct *hp, const char *buf, int count)
 665{
 666	struct hvsi_data packet __ALIGNED__;
 667	int ret;
 668
 669	BUG_ON(count > HVSI_MAX_OUTGOING_DATA);
 670
 671	packet.hdr.type = VS_DATA_PACKET_HEADER;
 672	packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
 673	packet.hdr.len = count + sizeof(struct hvsi_header);
 674	memcpy(&packet.data, buf, count);
 675
 676	ret = hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
 677	if (ret == packet.hdr.len) {
 678		/* return the number of chars written, not the packet length */
 679		return count;
 680	}
 681	return ret; /* return any errors */
 682}
 683
 684static void hvsi_close_protocol(struct hvsi_struct *hp)
 685{
 686	struct hvsi_control packet __ALIGNED__;
 687
 688	packet.hdr.type = VS_CONTROL_PACKET_HEADER;
 689	packet.hdr.seqno = cpu_to_be16(atomic_inc_return(&hp->seqno));
 690	packet.hdr.len = 6;
 691	packet.verb = cpu_to_be16(VSV_CLOSE_PROTOCOL);
 692
 693	pr_debug("%s: sending %i bytes\n", __func__, packet.hdr.len);
 694	dbg_dump_hex((uint8_t*)&packet, packet.hdr.len);
 695
 696	hvc_put_chars(hp->vtermno, (char *)&packet, packet.hdr.len);
 697}
 698
 699static int hvsi_open(struct tty_struct *tty, struct file *filp)
 700{
 701	struct hvsi_struct *hp;
 702	unsigned long flags;
 703	int ret;
 704
 705	pr_debug("%s\n", __func__);
 706
 707	hp = &hvsi_ports[tty->index];
 708
 709	tty->driver_data = hp;
 710
 711	mb();
 712	if (hp->state == HVSI_FSP_DIED)
 713		return -EIO;
 714
 715	tty_port_tty_set(&hp->port, tty);
 716	spin_lock_irqsave(&hp->lock, flags);
 717	hp->port.count++;
 718	atomic_set(&hp->seqno, 0);
 719	h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
 720	spin_unlock_irqrestore(&hp->lock, flags);
 721
 722	if (is_console(hp))
 723		return 0; /* this has already been handshaked as the console */
 724
 725	ret = hvsi_handshake(hp);
 726	if (ret < 0) {
 727		printk(KERN_ERR "%s: HVSI handshaking failed\n", tty->name);
 728		return ret;
 729	}
 730
 731	ret = hvsi_get_mctrl(hp);
 732	if (ret < 0) {
 733		printk(KERN_ERR "%s: couldn't get initial modem flags\n", tty->name);
 734		return ret;
 735	}
 736
 737	ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
 738	if (ret < 0) {
 739		printk(KERN_ERR "%s: couldn't set DTR\n", tty->name);
 740		return ret;
 741	}
 742
 743	return 0;
 744}
 745
 746/* wait for hvsi_write_worker to empty hp->outbuf */
 747static void hvsi_flush_output(struct hvsi_struct *hp)
 748{
 749	wait_event_timeout(hp->emptyq, (hp->n_outbuf <= 0), HVSI_TIMEOUT);
 750
 751	/* 'writer' could still be pending if it didn't see n_outbuf = 0 yet */
 752	cancel_delayed_work_sync(&hp->writer);
 753	flush_work(&hp->handshaker);
 754
 755	/*
 756	 * it's also possible that our timeout expired and hvsi_write_worker
 757	 * didn't manage to push outbuf. poof.
 758	 */
 759	hp->n_outbuf = 0;
 760}
 761
 762static void hvsi_close(struct tty_struct *tty, struct file *filp)
 763{
 764	struct hvsi_struct *hp = tty->driver_data;
 765	unsigned long flags;
 766
 767	pr_debug("%s\n", __func__);
 768
 769	if (tty_hung_up_p(filp))
 770		return;
 771
 772	spin_lock_irqsave(&hp->lock, flags);
 773
 774	if (--hp->port.count == 0) {
 775		tty_port_tty_set(&hp->port, NULL);
 776		hp->inbuf_end = hp->inbuf; /* discard remaining partial packets */
 777
 778		/* only close down connection if it is not the console */
 779		if (!is_console(hp)) {
 780			h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE); /* no more irqs */
 781			__set_state(hp, HVSI_CLOSED);
 782			/*
 783			 * any data delivered to the tty layer after this will be
 784			 * discarded (except for XON/XOFF)
 785			 */
 786			tty->closing = 1;
 787
 788			spin_unlock_irqrestore(&hp->lock, flags);
 789
 790			/* let any existing irq handlers finish. no more will start. */
 791			synchronize_irq(hp->virq);
 792
 793			/* hvsi_write_worker will re-schedule until outbuf is empty. */
 794			hvsi_flush_output(hp);
 795
 796			/* tell FSP to stop sending data */
 797			hvsi_close_protocol(hp);
 798
 799			/*
 800			 * drain anything FSP is still in the middle of sending, and let
 801			 * hvsi_handshake drain the rest on the next open.
 802			 */
 803			hvsi_drain_input(hp);
 804
 805			spin_lock_irqsave(&hp->lock, flags);
 806		}
 807	} else if (hp->port.count < 0)
 808		printk(KERN_ERR "hvsi_close %lu: oops, count is %d\n",
 809		       hp - hvsi_ports, hp->port.count);
 810
 811	spin_unlock_irqrestore(&hp->lock, flags);
 812}
 813
 814static void hvsi_hangup(struct tty_struct *tty)
 815{
 816	struct hvsi_struct *hp = tty->driver_data;
 817	unsigned long flags;
 818
 819	pr_debug("%s\n", __func__);
 820
 821	tty_port_tty_set(&hp->port, NULL);
 822
 823	spin_lock_irqsave(&hp->lock, flags);
 824	hp->port.count = 0;
 825	hp->n_outbuf = 0;
 826	spin_unlock_irqrestore(&hp->lock, flags);
 827}
 828
 829/* called with hp->lock held */
 830static void hvsi_push(struct hvsi_struct *hp)
 831{
 832	int n;
 833
 834	if (hp->n_outbuf <= 0)
 835		return;
 836
 837	n = hvsi_put_chars(hp, hp->outbuf, hp->n_outbuf);
 838	if (n > 0) {
 839		/* success */
 840		pr_debug("%s: wrote %i chars\n", __func__, n);
 841		hp->n_outbuf = 0;
 842	} else if (n == -EIO) {
 843		__set_state(hp, HVSI_FSP_DIED);
 844		printk(KERN_ERR "hvsi%i: service processor died\n", hp->index);
 845	}
 846}
 847
 848/* hvsi_write_worker will keep rescheduling itself until outbuf is empty */
 849static void hvsi_write_worker(struct work_struct *work)
 850{
 851	struct hvsi_struct *hp =
 852		container_of(work, struct hvsi_struct, writer.work);
 853	unsigned long flags;
 854#ifdef DEBUG
 855	static long start_j = 0;
 856
 857	if (start_j == 0)
 858		start_j = jiffies;
 859#endif /* DEBUG */
 860
 861	spin_lock_irqsave(&hp->lock, flags);
 862
 863	pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
 864
 865	if (!is_open(hp)) {
 866		/*
 867		 * We could have a non-open connection if the service processor died
 868		 * while we were busily scheduling ourselves. In that case, it could
 869		 * be minutes before the service processor comes back, so only try
 870		 * again once a second.
 871		 */
 872		schedule_delayed_work(&hp->writer, HZ);
 873		goto out;
 874	}
 875
 876	hvsi_push(hp);
 877	if (hp->n_outbuf > 0)
 878		schedule_delayed_work(&hp->writer, 10);
 879	else {
 880#ifdef DEBUG
 881		pr_debug("%s: outbuf emptied after %li jiffies\n", __func__,
 882				jiffies - start_j);
 883		start_j = 0;
 884#endif /* DEBUG */
 885		wake_up_all(&hp->emptyq);
 886		tty_port_tty_wakeup(&hp->port);
 887	}
 888
 889out:
 890	spin_unlock_irqrestore(&hp->lock, flags);
 891}
 892
 893static unsigned int hvsi_write_room(struct tty_struct *tty)
 894{
 895	struct hvsi_struct *hp = tty->driver_data;
 896
 897	return N_OUTBUF - hp->n_outbuf;
 898}
 899
 900static unsigned int hvsi_chars_in_buffer(struct tty_struct *tty)
 901{
 902	struct hvsi_struct *hp = tty->driver_data;
 903
 904	return hp->n_outbuf;
 905}
 906
 907static ssize_t hvsi_write(struct tty_struct *tty, const u8 *source,
 908			  size_t count)
 909{
 910	struct hvsi_struct *hp = tty->driver_data;
 
 911	unsigned long flags;
 912	size_t total = 0;
 913	size_t origcount = count;
 914
 915	spin_lock_irqsave(&hp->lock, flags);
 916
 917	pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
 918
 919	if (!is_open(hp)) {
 920		/* we're either closing or not yet open; don't accept data */
 921		pr_debug("%s: not open\n", __func__);
 922		goto out;
 923	}
 924
 925	/*
 926	 * when the hypervisor buffer (16K) fills, data will stay in hp->outbuf
 927	 * and hvsi_write_worker will be scheduled. subsequent hvsi_write() calls
 928	 * will see there is no room in outbuf and return.
 929	 */
 930	while ((count > 0) && (hvsi_write_room(tty) > 0)) {
 931		size_t chunksize = min_t(size_t, count, hvsi_write_room(tty));
 932
 933		BUG_ON(hp->n_outbuf < 0);
 934		memcpy(hp->outbuf + hp->n_outbuf, source, chunksize);
 935		hp->n_outbuf += chunksize;
 936
 937		total += chunksize;
 938		source += chunksize;
 939		count -= chunksize;
 940		hvsi_push(hp);
 941	}
 942
 943	if (hp->n_outbuf > 0) {
 944		/*
 945		 * we weren't able to write it all to the hypervisor.
 946		 * schedule another push attempt.
 947		 */
 948		schedule_delayed_work(&hp->writer, 10);
 949	}
 950
 951out:
 952	spin_unlock_irqrestore(&hp->lock, flags);
 953
 954	if (total != origcount)
 955		pr_debug("%s: wanted %zu, only wrote %zu\n", __func__,
 956			 origcount, total);
 957
 958	return total;
 959}
 960
 961/*
 962 * I have never seen throttle or unthrottle called, so this little throttle
 963 * buffering scheme may or may not work.
 964 */
 965static void hvsi_throttle(struct tty_struct *tty)
 966{
 967	struct hvsi_struct *hp = tty->driver_data;
 968
 969	pr_debug("%s\n", __func__);
 970
 971	h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE);
 972}
 973
 974static void hvsi_unthrottle(struct tty_struct *tty)
 975{
 976	struct hvsi_struct *hp = tty->driver_data;
 977	unsigned long flags;
 978
 979	pr_debug("%s\n", __func__);
 980
 981	spin_lock_irqsave(&hp->lock, flags);
 982	if (hp->n_throttle) {
 983		hvsi_send_overflow(hp);
 984		tty_flip_buffer_push(&hp->port);
 985	}
 986	spin_unlock_irqrestore(&hp->lock, flags);
 987
 988
 989	h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
 990}
 991
 992static int hvsi_tiocmget(struct tty_struct *tty)
 993{
 994	struct hvsi_struct *hp = tty->driver_data;
 995
 996	hvsi_get_mctrl(hp);
 997	return hp->mctrl;
 998}
 999
1000static int hvsi_tiocmset(struct tty_struct *tty,
1001				unsigned int set, unsigned int clear)
1002{
1003	struct hvsi_struct *hp = tty->driver_data;
1004	unsigned long flags;
1005	uint16_t new_mctrl;
1006
1007	/* we can only alter DTR */
1008	clear &= TIOCM_DTR;
1009	set &= TIOCM_DTR;
1010
1011	spin_lock_irqsave(&hp->lock, flags);
1012
1013	new_mctrl = (hp->mctrl & ~clear) | set;
1014
1015	if (hp->mctrl != new_mctrl) {
1016		hvsi_set_mctrl(hp, new_mctrl);
1017		hp->mctrl = new_mctrl;
1018	}
1019	spin_unlock_irqrestore(&hp->lock, flags);
1020
1021	return 0;
1022}
1023
1024
1025static const struct tty_operations hvsi_ops = {
1026	.open = hvsi_open,
1027	.close = hvsi_close,
1028	.write = hvsi_write,
1029	.hangup = hvsi_hangup,
1030	.write_room = hvsi_write_room,
1031	.chars_in_buffer = hvsi_chars_in_buffer,
1032	.throttle = hvsi_throttle,
1033	.unthrottle = hvsi_unthrottle,
1034	.tiocmget = hvsi_tiocmget,
1035	.tiocmset = hvsi_tiocmset,
1036};
1037
1038static int __init hvsi_init(void)
1039{
1040	struct tty_driver *driver;
1041	int i, ret;
1042
1043	driver = tty_alloc_driver(hvsi_count, TTY_DRIVER_REAL_RAW);
1044	if (IS_ERR(driver))
1045		return PTR_ERR(driver);
1046
1047	driver->driver_name = "hvsi";
1048	driver->name = "hvsi";
1049	driver->major = HVSI_MAJOR;
1050	driver->minor_start = HVSI_MINOR;
1051	driver->type = TTY_DRIVER_TYPE_SYSTEM;
1052	driver->init_termios = tty_std_termios;
1053	driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL;
1054	driver->init_termios.c_ispeed = 9600;
1055	driver->init_termios.c_ospeed = 9600;
1056	tty_set_operations(driver, &hvsi_ops);
 
1057
1058	for (i=0; i < hvsi_count; i++) {
1059		struct hvsi_struct *hp = &hvsi_ports[i];
1060		int ret = 1;
1061
1062		tty_port_link_device(&hp->port, driver, i);
1063
1064		ret = request_irq(hp->virq, hvsi_interrupt, 0, "hvsi", hp);
1065		if (ret)
1066			printk(KERN_ERR "HVSI: couldn't reserve irq 0x%x (error %i)\n",
1067				hp->virq, ret);
1068	}
1069	hvsi_wait = wait_for_state; /* irqs active now */
1070
1071	ret = tty_register_driver(driver);
1072	if (ret) {
1073		pr_err("Couldn't register hvsi console driver\n");
1074		goto err_free_irq;
1075	}
1076
1077	hvsi_driver = driver;
1078
1079	printk(KERN_DEBUG "HVSI: registered %i devices\n", hvsi_count);
1080
1081	return 0;
1082err_free_irq:
1083	hvsi_wait = poll_for_state;
1084	for (i = 0; i < hvsi_count; i++) {
1085		struct hvsi_struct *hp = &hvsi_ports[i];
1086
1087		free_irq(hp->virq, hp);
1088	}
1089	tty_driver_kref_put(driver);
1090
1091	return ret;
1092}
1093device_initcall(hvsi_init);
1094
1095/***** console (not tty) code: *****/
1096
1097static void hvsi_console_print(struct console *console, const char *buf,
1098		unsigned int count)
1099{
1100	struct hvsi_struct *hp = &hvsi_ports[console->index];
1101	char c[HVSI_MAX_OUTGOING_DATA] __ALIGNED__;
1102	unsigned int i = 0, n = 0;
1103	int ret, donecr = 0;
1104
1105	mb();
1106	if (!is_open(hp))
1107		return;
1108
1109	/*
1110	 * ugh, we have to translate LF -> CRLF ourselves, in place.
1111	 * copied from hvc_console.c:
1112	 */
1113	while (count > 0 || i > 0) {
1114		if (count > 0 && i < sizeof(c)) {
1115			if (buf[n] == '\n' && !donecr) {
1116				c[i++] = '\r';
1117				donecr = 1;
1118			} else {
1119				c[i++] = buf[n++];
1120				donecr = 0;
1121				--count;
1122			}
1123		} else {
1124			ret = hvsi_put_chars(hp, c, i);
1125			if (ret < 0)
1126				i = 0;
1127			i -= ret;
1128		}
1129	}
1130}
1131
1132static struct tty_driver *hvsi_console_device(struct console *console,
1133	int *index)
1134{
1135	*index = console->index;
1136	return hvsi_driver;
1137}
1138
1139static int __init hvsi_console_setup(struct console *console, char *options)
1140{
1141	struct hvsi_struct *hp;
1142	int ret;
1143
1144	if (console->index < 0 || console->index >= hvsi_count)
1145		return -EINVAL;
1146	hp = &hvsi_ports[console->index];
1147
1148	/* give the FSP a chance to change the baud rate when we re-open */
1149	hvsi_close_protocol(hp);
1150
1151	ret = hvsi_handshake(hp);
1152	if (ret < 0)
1153		return ret;
1154
1155	ret = hvsi_get_mctrl(hp);
1156	if (ret < 0)
1157		return ret;
1158
1159	ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
1160	if (ret < 0)
1161		return ret;
1162
1163	hp->flags |= HVSI_CONSOLE;
1164
1165	return 0;
1166}
1167
1168static struct console hvsi_console = {
1169	.name		= "hvsi",
1170	.write		= hvsi_console_print,
1171	.device		= hvsi_console_device,
1172	.setup		= hvsi_console_setup,
1173	.flags		= CON_PRINTBUFFER,
1174	.index		= -1,
1175};
1176
1177static int __init hvsi_console_init(void)
1178{
1179	struct device_node *vty;
1180
1181	hvsi_wait = poll_for_state; /* no irqs yet; must poll */
1182
1183	/* search device tree for vty nodes */
1184	for_each_compatible_node(vty, "serial", "hvterm-protocol") {
1185		struct hvsi_struct *hp;
1186		const __be32 *vtermno, *irq;
1187
1188		vtermno = of_get_property(vty, "reg", NULL);
1189		irq = of_get_property(vty, "interrupts", NULL);
1190		if (!vtermno || !irq)
1191			continue;
1192
1193		if (hvsi_count >= MAX_NR_HVSI_CONSOLES) {
1194			of_node_put(vty);
1195			break;
1196		}
1197
1198		hp = &hvsi_ports[hvsi_count];
1199		INIT_DELAYED_WORK(&hp->writer, hvsi_write_worker);
1200		INIT_WORK(&hp->handshaker, hvsi_handshaker);
1201		init_waitqueue_head(&hp->emptyq);
1202		init_waitqueue_head(&hp->stateq);
1203		spin_lock_init(&hp->lock);
1204		tty_port_init(&hp->port);
1205		hp->index = hvsi_count;
1206		hp->inbuf_end = hp->inbuf;
1207		hp->state = HVSI_CLOSED;
1208		hp->vtermno = be32_to_cpup(vtermno);
1209		hp->virq = irq_create_mapping(NULL, be32_to_cpup(irq));
1210		if (hp->virq == 0) {
1211			printk(KERN_ERR "%s: couldn't create irq mapping for 0x%x\n",
1212			       __func__, be32_to_cpup(irq));
1213			tty_port_destroy(&hp->port);
1214			continue;
1215		}
1216
1217		hvsi_count++;
1218	}
1219
1220	if (hvsi_count)
1221		register_console(&hvsi_console);
1222	return 0;
1223}
1224console_initcall(hvsi_console_init);