1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Virtio-based remote processor messaging bus
   4 *
   5 * Copyright (C) 2011 Texas Instruments, Inc.
   6 * Copyright (C) 2011 Google, Inc.
   7 *
   8 * Ohad Ben-Cohen <ohad@wizery.com>
   9 * Brian Swetland <swetland@google.com>
  10 */
  11
  12#define pr_fmt(fmt) "%s: " fmt, __func__
  13
  14#include <linux/dma-mapping.h>
  15#include <linux/idr.h>
  16#include <linux/jiffies.h>
  17#include <linux/kernel.h>
  18#include <linux/module.h>
  19#include <linux/mutex.h>
  20#include <linux/rpmsg.h>
  21#include <linux/rpmsg/byteorder.h>
  22#include <linux/rpmsg/ns.h>
  23#include <linux/scatterlist.h>
  24#include <linux/slab.h>
  25#include <linux/sched.h>
  26#include <linux/virtio.h>
  27#include <linux/virtio_ids.h>
  28#include <linux/virtio_config.h>
  29#include <linux/wait.h>
  30
  31#include "rpmsg_internal.h"
  32
  33/**
  34 * struct virtproc_info - virtual remote processor state
  35 * @vdev:	the virtio device
  36 * @rvq:	rx virtqueue
  37 * @svq:	tx virtqueue
  38 * @rbufs:	kernel address of rx buffers
  39 * @sbufs:	kernel address of tx buffers
  40 * @num_bufs:	total number of buffers for rx and tx
  41 * @buf_size:   size of one rx or tx buffer
  42 * @last_sbuf:	index of last tx buffer used
  43 * @bufs_dma:	dma base addr of the buffers
  44 * @tx_lock:	protects svq, sbufs and sleepers, to allow concurrent senders.
  45 *		sending a message might require waking up a dozing remote
  46 *		processor, which involves sleeping, hence the mutex.
  47 * @endpoints:	idr of local endpoints, allows fast retrieval
  48 * @endpoints_lock: lock of the endpoints set
  49 * @sendq:	wait queue of sending contexts waiting for a tx buffers
  50 * @sleepers:	number of senders that are waiting for a tx buffer
  51 *
  52 * This structure stores the rpmsg state of a given virtio remote processor
  53 * device (there might be several virtio proc devices for each physical
  54 * remote processor).
  55 */
  56struct virtproc_info {
  57	struct virtio_device *vdev;
  58	struct virtqueue *rvq, *svq;
  59	void *rbufs, *sbufs;
  60	unsigned int num_bufs;
  61	unsigned int buf_size;
  62	int last_sbuf;
  63	dma_addr_t bufs_dma;
  64	struct mutex tx_lock;
  65	struct idr endpoints;
  66	struct mutex endpoints_lock;
  67	wait_queue_head_t sendq;
  68	atomic_t sleepers;
  69};
  70
  71/* The feature bitmap for virtio rpmsg */
  72#define VIRTIO_RPMSG_F_NS	0 /* RP supports name service notifications */
  73
  74/**
  75 * struct rpmsg_hdr - common header for all rpmsg messages
  76 * @src: source address
  77 * @dst: destination address
  78 * @reserved: reserved for future use
  79 * @len: length of payload (in bytes)
  80 * @flags: message flags
  81 * @data: @len bytes of message payload data
  82 *
  83 * Every message sent(/received) on the rpmsg bus begins with this header.
  84 */
  85struct rpmsg_hdr {
  86	__rpmsg32 src;
  87	__rpmsg32 dst;
  88	__rpmsg32 reserved;
  89	__rpmsg16 len;
  90	__rpmsg16 flags;
  91	u8 data[];
  92} __packed;
  93
  94
  95/**
  96 * struct virtio_rpmsg_channel - rpmsg channel descriptor
  97 * @rpdev: the rpmsg channel device
  98 * @vrp: the virtio remote processor device this channel belongs to
  99 *
 100 * This structure stores the channel that links the rpmsg device to the virtio
 101 * remote processor device.
 102 */
 103struct virtio_rpmsg_channel {
 104	struct rpmsg_device rpdev;
 105
 106	struct virtproc_info *vrp;
 107};
 108
 109#define to_virtio_rpmsg_channel(_rpdev) \
 110	container_of(_rpdev, struct virtio_rpmsg_channel, rpdev)
 111
 112/*
 113 * We're allocating buffers of 512 bytes each for communications. The
 114 * number of buffers will be computed from the number of buffers supported
 115 * by the vring, upto a maximum of 512 buffers (256 in each direction).
 116 *
 117 * Each buffer will have 16 bytes for the msg header and 496 bytes for
 118 * the payload.
 119 *
 120 * This will utilize a maximum total space of 256KB for the buffers.
 121 *
 122 * We might also want to add support for user-provided buffers in time.
 123 * This will allow bigger buffer size flexibility, and can also be used
 124 * to achieve zero-copy messaging.
 125 *
 126 * Note that these numbers are purely a decision of this driver - we
 127 * can change this without changing anything in the firmware of the remote
 128 * processor.
 129 */
 130#define MAX_RPMSG_NUM_BUFS	(512)
 131#define MAX_RPMSG_BUF_SIZE	(512)
 132
 133/*
 134 * Local addresses are dynamically allocated on-demand.
 135 * We do not dynamically assign addresses from the low 1024 range,
 136 * in order to reserve that address range for predefined services.
 137 */
 138#define RPMSG_RESERVED_ADDRESSES	(1024)
 139
 140static void virtio_rpmsg_destroy_ept(struct rpmsg_endpoint *ept);
 141static int virtio_rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len);
 142static int virtio_rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len,
 143			       u32 dst);
 144static int virtio_rpmsg_send_offchannel(struct rpmsg_endpoint *ept, u32 src,
 145					u32 dst, void *data, int len);
 146static int virtio_rpmsg_trysend(struct rpmsg_endpoint *ept, void *data, int len);
 147static int virtio_rpmsg_trysendto(struct rpmsg_endpoint *ept, void *data,
 148				  int len, u32 dst);
 149static int virtio_rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src,
 150					   u32 dst, void *data, int len);
 151static ssize_t virtio_rpmsg_get_mtu(struct rpmsg_endpoint *ept);
 152static struct rpmsg_device *__rpmsg_create_channel(struct virtproc_info *vrp,
 153						   struct rpmsg_channel_info *chinfo);
 154
 155static const struct rpmsg_endpoint_ops virtio_endpoint_ops = {
 156	.destroy_ept = virtio_rpmsg_destroy_ept,
 157	.send = virtio_rpmsg_send,
 158	.sendto = virtio_rpmsg_sendto,
 159	.send_offchannel = virtio_rpmsg_send_offchannel,
 160	.trysend = virtio_rpmsg_trysend,
 161	.trysendto = virtio_rpmsg_trysendto,
 162	.trysend_offchannel = virtio_rpmsg_trysend_offchannel,
 163	.get_mtu = virtio_rpmsg_get_mtu,
 164};
 165
 166/**
 167 * rpmsg_sg_init - initialize scatterlist according to cpu address location
 168 * @sg: scatterlist to fill
 169 * @cpu_addr: virtual address of the buffer
 170 * @len: buffer length
 171 *
 172 * An internal function filling scatterlist according to virtual address
 173 * location (in vmalloc or in kernel).
 174 */
 175static void
 176rpmsg_sg_init(struct scatterlist *sg, void *cpu_addr, unsigned int len)
 177{
 178	if (is_vmalloc_addr(cpu_addr)) {
 179		sg_init_table(sg, 1);
 180		sg_set_page(sg, vmalloc_to_page(cpu_addr), len,
 181			    offset_in_page(cpu_addr));
 182	} else {
 183		WARN_ON(!virt_addr_valid(cpu_addr));
 184		sg_init_one(sg, cpu_addr, len);
 185	}
 186}
 187
 188/**
 189 * __ept_release() - deallocate an rpmsg endpoint
 190 * @kref: the ept's reference count
 191 *
 192 * This function deallocates an ept, and is invoked when its @kref refcount
 193 * drops to zero.
 194 *
 195 * Never invoke this function directly!
 196 */
 197static void __ept_release(struct kref *kref)
 198{
 199	struct rpmsg_endpoint *ept = container_of(kref, struct rpmsg_endpoint,
 200						  refcount);
 201	/*
 202	 * At this point no one holds a reference to ept anymore,
 203	 * so we can directly free it
 204	 */
 205	kfree(ept);
 206}
 207
 208/* for more info, see below documentation of rpmsg_create_ept() */
 209static struct rpmsg_endpoint *__rpmsg_create_ept(struct virtproc_info *vrp,
 210						 struct rpmsg_device *rpdev,
 211						 rpmsg_rx_cb_t cb,
 212						 void *priv, u32 addr)
 213{
 214	int id_min, id_max, id;
 215	struct rpmsg_endpoint *ept;
 216	struct device *dev = rpdev ? &rpdev->dev : &vrp->vdev->dev;
 217
 218	ept = kzalloc(sizeof(*ept), GFP_KERNEL);
 219	if (!ept)
 220		return NULL;
 221
 222	kref_init(&ept->refcount);
 223	mutex_init(&ept->cb_lock);
 224
 225	ept->rpdev = rpdev;
 226	ept->cb = cb;
 227	ept->priv = priv;
 228	ept->ops = &virtio_endpoint_ops;
 229
 230	/* do we need to allocate a local address ? */
 231	if (addr == RPMSG_ADDR_ANY) {
 232		id_min = RPMSG_RESERVED_ADDRESSES;
 233		id_max = 0;
 234	} else {
 235		id_min = addr;
 236		id_max = addr + 1;
 237	}
 238
 239	mutex_lock(&vrp->endpoints_lock);
 240
 241	/* bind the endpoint to an rpmsg address (and allocate one if needed) */
 242	id = idr_alloc(&vrp->endpoints, ept, id_min, id_max, GFP_KERNEL);
 243	if (id < 0) {
 244		dev_err(dev, "idr_alloc failed: %d\n", id);
 245		goto free_ept;
 246	}
 247	ept->addr = id;
 248
 249	mutex_unlock(&vrp->endpoints_lock);
 250
 251	return ept;
 252
 253free_ept:
 254	mutex_unlock(&vrp->endpoints_lock);
 255	kref_put(&ept->refcount, __ept_release);
 256	return NULL;
 257}
 258
 259static struct rpmsg_device *virtio_rpmsg_create_channel(struct rpmsg_device *rpdev,
 260							struct rpmsg_channel_info *chinfo)
 261{
 262	struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
 263	struct virtproc_info *vrp = vch->vrp;
 264
 265	return __rpmsg_create_channel(vrp, chinfo);
 266}
 267
 268static int virtio_rpmsg_release_channel(struct rpmsg_device *rpdev,
 269					struct rpmsg_channel_info *chinfo)
 270{
 271	struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
 272	struct virtproc_info *vrp = vch->vrp;
 273
 274	return rpmsg_unregister_device(&vrp->vdev->dev, chinfo);
 275}
 276
 277static struct rpmsg_endpoint *virtio_rpmsg_create_ept(struct rpmsg_device *rpdev,
 278						      rpmsg_rx_cb_t cb,
 279						      void *priv,
 280						      struct rpmsg_channel_info chinfo)
 281{
 282	struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
 283
 284	return __rpmsg_create_ept(vch->vrp, rpdev, cb, priv, chinfo.src);
 285}
 286
 287/**
 288 * __rpmsg_destroy_ept() - destroy an existing rpmsg endpoint
 289 * @vrp: virtproc which owns this ept
 290 * @ept: endpoing to destroy
 291 *
 292 * An internal function which destroy an ept without assuming it is
 293 * bound to an rpmsg channel. This is needed for handling the internal
 294 * name service endpoint, which isn't bound to an rpmsg channel.
 295 * See also __rpmsg_create_ept().
 296 */
 297static void
 298__rpmsg_destroy_ept(struct virtproc_info *vrp, struct rpmsg_endpoint *ept)
 299{
 300	/* make sure new inbound messages can't find this ept anymore */
 301	mutex_lock(&vrp->endpoints_lock);
 302	idr_remove(&vrp->endpoints, ept->addr);
 303	mutex_unlock(&vrp->endpoints_lock);
 304
 305	/* make sure in-flight inbound messages won't invoke cb anymore */
 306	mutex_lock(&ept->cb_lock);
 307	ept->cb = NULL;
 308	mutex_unlock(&ept->cb_lock);
 309
 310	kref_put(&ept->refcount, __ept_release);
 311}
 312
 313static void virtio_rpmsg_destroy_ept(struct rpmsg_endpoint *ept)
 314{
 315	struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(ept->rpdev);
 316
 317	__rpmsg_destroy_ept(vch->vrp, ept);
 318}
 319
 320static int virtio_rpmsg_announce_create(struct rpmsg_device *rpdev)
 321{
 322	struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
 323	struct virtproc_info *vrp = vch->vrp;
 324	struct device *dev = &rpdev->dev;
 325	int err = 0;
 326
 327	/* need to tell remote processor's name service about this channel ? */
 328	if (rpdev->announce && rpdev->ept &&
 329	    virtio_has_feature(vrp->vdev, VIRTIO_RPMSG_F_NS)) {
 330		struct rpmsg_ns_msg nsm;
 331
 332		strscpy_pad(nsm.name, rpdev->id.name, sizeof(nsm.name));
 333		nsm.addr = cpu_to_rpmsg32(rpdev, rpdev->ept->addr);
 334		nsm.flags = cpu_to_rpmsg32(rpdev, RPMSG_NS_CREATE);
 335
 336		err = rpmsg_sendto(rpdev->ept, &nsm, sizeof(nsm), RPMSG_NS_ADDR);
 337		if (err)
 338			dev_err(dev, "failed to announce service %d\n", err);
 339	}
 340
 341	return err;
 342}
 343
 344static int virtio_rpmsg_announce_destroy(struct rpmsg_device *rpdev)
 345{
 346	struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
 347	struct virtproc_info *vrp = vch->vrp;
 348	struct device *dev = &rpdev->dev;
 349	int err = 0;
 350
 351	/* tell remote processor's name service we're removing this channel */
 352	if (rpdev->announce && rpdev->ept &&
 353	    virtio_has_feature(vrp->vdev, VIRTIO_RPMSG_F_NS)) {
 354		struct rpmsg_ns_msg nsm;
 355
 356		strscpy_pad(nsm.name, rpdev->id.name, sizeof(nsm.name));
 357		nsm.addr = cpu_to_rpmsg32(rpdev, rpdev->ept->addr);
 358		nsm.flags = cpu_to_rpmsg32(rpdev, RPMSG_NS_DESTROY);
 359
 360		err = rpmsg_sendto(rpdev->ept, &nsm, sizeof(nsm), RPMSG_NS_ADDR);
 361		if (err)
 362			dev_err(dev, "failed to announce service %d\n", err);
 363	}
 364
 365	return err;
 366}
 367
 368static const struct rpmsg_device_ops virtio_rpmsg_ops = {
 369	.create_channel = virtio_rpmsg_create_channel,
 370	.release_channel = virtio_rpmsg_release_channel,
 371	.create_ept = virtio_rpmsg_create_ept,
 372	.announce_create = virtio_rpmsg_announce_create,
 373	.announce_destroy = virtio_rpmsg_announce_destroy,
 374};
 375
 376static void virtio_rpmsg_release_device(struct device *dev)
 377{
 378	struct rpmsg_device *rpdev = to_rpmsg_device(dev);
 379	struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
 380
 381	kfree(rpdev->driver_override);
 382	kfree(vch);
 383}
 384
 385/*
 386 * create an rpmsg channel using its name and address info.
 387 * this function will be used to create both static and dynamic
 388 * channels.
 389 */
 390static struct rpmsg_device *__rpmsg_create_channel(struct virtproc_info *vrp,
 391						   struct rpmsg_channel_info *chinfo)
 392{
 393	struct virtio_rpmsg_channel *vch;
 394	struct rpmsg_device *rpdev;
 395	struct device *tmp, *dev = &vrp->vdev->dev;
 396	int ret;
 397
 398	/* make sure a similar channel doesn't already exist */
 399	tmp = rpmsg_find_device(dev, chinfo);
 400	if (tmp) {
 401		/* decrement the matched device's refcount back */
 402		put_device(tmp);
 403		dev_err(dev, "channel %s:%x:%x already exist\n",
 404				chinfo->name, chinfo->src, chinfo->dst);
 405		return NULL;
 406	}
 407
 408	vch = kzalloc(sizeof(*vch), GFP_KERNEL);
 409	if (!vch)
 410		return NULL;
 411
 412	/* Link the channel to our vrp */
 413	vch->vrp = vrp;
 414
 415	/* Assign public information to the rpmsg_device */
 416	rpdev = &vch->rpdev;
 417	rpdev->src = chinfo->src;
 418	rpdev->dst = chinfo->dst;
 419	rpdev->ops = &virtio_rpmsg_ops;
 420	rpdev->little_endian = virtio_is_little_endian(vrp->vdev);
 421
 422	/*
 423	 * rpmsg server channels has predefined local address (for now),
 424	 * and their existence needs to be announced remotely
 425	 */
 426	rpdev->announce = rpdev->src != RPMSG_ADDR_ANY;
 427
 428	strscpy(rpdev->id.name, chinfo->name, sizeof(rpdev->id.name));
 429
 430	rpdev->dev.parent = &vrp->vdev->dev;
 431	rpdev->dev.release = virtio_rpmsg_release_device;
 432	ret = rpmsg_register_device(rpdev);
 433	if (ret)
 434		return NULL;
 435
 436	return rpdev;
 437}
 438
 439/* super simple buffer "allocator" that is just enough for now */
 440static void *get_a_tx_buf(struct virtproc_info *vrp)
 441{
 442	unsigned int len;
 443	void *ret;
 444
 445	/* support multiple concurrent senders */
 446	mutex_lock(&vrp->tx_lock);
 447
 448	/*
 449	 * either pick the next unused tx buffer
 450	 * (half of our buffers are used for sending messages)
 451	 */
 452	if (vrp->last_sbuf < vrp->num_bufs / 2)
 453		ret = vrp->sbufs + vrp->buf_size * vrp->last_sbuf++;
 454	/* or recycle a used one */
 455	else
 456		ret = virtqueue_get_buf(vrp->svq, &len);
 457
 458	mutex_unlock(&vrp->tx_lock);
 459
 460	return ret;
 461}
 462
 463/**
 464 * rpmsg_upref_sleepers() - enable "tx-complete" interrupts, if needed
 465 * @vrp: virtual remote processor state
 466 *
 467 * This function is called before a sender is blocked, waiting for
 468 * a tx buffer to become available.
 469 *
 470 * If we already have blocking senders, this function merely increases
 471 * the "sleepers" reference count, and exits.
 472 *
 473 * Otherwise, if this is the first sender to block, we also enable
 474 * virtio's tx callbacks, so we'd be immediately notified when a tx
 475 * buffer is consumed (we rely on virtio's tx callback in order
 476 * to wake up sleeping senders as soon as a tx buffer is used by the
 477 * remote processor).
 478 */
 479static void rpmsg_upref_sleepers(struct virtproc_info *vrp)
 480{
 481	/* support multiple concurrent senders */
 482	mutex_lock(&vrp->tx_lock);
 483
 484	/* are we the first sleeping context waiting for tx buffers ? */
 485	if (atomic_inc_return(&vrp->sleepers) == 1)
 486		/* enable "tx-complete" interrupts before dozing off */
 487		virtqueue_enable_cb(vrp->svq);
 488
 489	mutex_unlock(&vrp->tx_lock);
 490}
 491
 492/**
 493 * rpmsg_downref_sleepers() - disable "tx-complete" interrupts, if needed
 494 * @vrp: virtual remote processor state
 495 *
 496 * This function is called after a sender, that waited for a tx buffer
 497 * to become available, is unblocked.
 498 *
 499 * If we still have blocking senders, this function merely decreases
 500 * the "sleepers" reference count, and exits.
 501 *
 502 * Otherwise, if there are no more blocking senders, we also disable
 503 * virtio's tx callbacks, to avoid the overhead incurred with handling
 504 * those (now redundant) interrupts.
 505 */
 506static void rpmsg_downref_sleepers(struct virtproc_info *vrp)
 507{
 508	/* support multiple concurrent senders */
 509	mutex_lock(&vrp->tx_lock);
 510
 511	/* are we the last sleeping context waiting for tx buffers ? */
 512	if (atomic_dec_and_test(&vrp->sleepers))
 513		/* disable "tx-complete" interrupts */
 514		virtqueue_disable_cb(vrp->svq);
 515
 516	mutex_unlock(&vrp->tx_lock);
 517}
 518
 519/**
 520 * rpmsg_send_offchannel_raw() - send a message across to the remote processor
 521 * @rpdev: the rpmsg channel
 522 * @src: source address
 523 * @dst: destination address
 524 * @data: payload of message
 525 * @len: length of payload
 526 * @wait: indicates whether caller should block in case no TX buffers available
 527 *
 528 * This function is the base implementation for all of the rpmsg sending API.
 529 *
 530 * It will send @data of length @len to @dst, and say it's from @src. The
 531 * message will be sent to the remote processor which the @rpdev channel
 532 * belongs to.
 533 *
 534 * The message is sent using one of the TX buffers that are available for
 535 * communication with this remote processor.
 536 *
 537 * If @wait is true, the caller will be blocked until either a TX buffer is
 538 * available, or 15 seconds elapses (we don't want callers to
 539 * sleep indefinitely due to misbehaving remote processors), and in that
 540 * case -ERESTARTSYS is returned. The number '15' itself was picked
 541 * arbitrarily; there's little point in asking drivers to provide a timeout
 542 * value themselves.
 543 *
 544 * Otherwise, if @wait is false, and there are no TX buffers available,
 545 * the function will immediately fail, and -ENOMEM will be returned.
 546 *
 547 * Normally drivers shouldn't use this function directly; instead, drivers
 548 * should use the appropriate rpmsg_{try}send{to, _offchannel} API
 549 * (see include/linux/rpmsg.h).
 550 *
 551 * Return: 0 on success and an appropriate error value on failure.
 552 */
 553static int rpmsg_send_offchannel_raw(struct rpmsg_device *rpdev,
 554				     u32 src, u32 dst,
 555				     void *data, int len, bool wait)
 556{
 557	struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
 558	struct virtproc_info *vrp = vch->vrp;
 559	struct device *dev = &rpdev->dev;
 560	struct scatterlist sg;
 561	struct rpmsg_hdr *msg;
 562	int err;
 563
 564	/* bcasting isn't allowed */
 565	if (src == RPMSG_ADDR_ANY || dst == RPMSG_ADDR_ANY) {
 566		dev_err(dev, "invalid addr (src 0x%x, dst 0x%x)\n", src, dst);
 567		return -EINVAL;
 568	}
 569
 570	/*
 571	 * We currently use fixed-sized buffers, and therefore the payload
 572	 * length is limited.
 573	 *
 574	 * One of the possible improvements here is either to support
 575	 * user-provided buffers (and then we can also support zero-copy
 576	 * messaging), or to improve the buffer allocator, to support
 577	 * variable-length buffer sizes.
 578	 */
 579	if (len > vrp->buf_size - sizeof(struct rpmsg_hdr)) {
 580		dev_err(dev, "message is too big (%d)\n", len);
 581		return -EMSGSIZE;
 582	}
 583
 584	/* grab a buffer */
 585	msg = get_a_tx_buf(vrp);
 586	if (!msg && !wait)
 587		return -ENOMEM;
 588
 589	/* no free buffer ? wait for one (but bail after 15 seconds) */
 590	while (!msg) {
 591		/* enable "tx-complete" interrupts, if not already enabled */
 592		rpmsg_upref_sleepers(vrp);
 593
 594		/*
 595		 * sleep until a free buffer is available or 15 secs elapse.
 596		 * the timeout period is not configurable because there's
 597		 * little point in asking drivers to specify that.
 598		 * if later this happens to be required, it'd be easy to add.
 599		 */
 600		err = wait_event_interruptible_timeout(vrp->sendq,
 601					(msg = get_a_tx_buf(vrp)),
 602					msecs_to_jiffies(15000));
 603
 604		/* disable "tx-complete" interrupts if we're the last sleeper */
 605		rpmsg_downref_sleepers(vrp);
 606
 607		/* timeout ? */
 608		if (!err) {
 609			dev_err(dev, "timeout waiting for a tx buffer\n");
 610			return -ERESTARTSYS;
 611		}
 612	}
 613
 614	msg->len = cpu_to_rpmsg16(rpdev, len);
 615	msg->flags = 0;
 616	msg->src = cpu_to_rpmsg32(rpdev, src);
 617	msg->dst = cpu_to_rpmsg32(rpdev, dst);
 618	msg->reserved = 0;
 619	memcpy(msg->data, data, len);
 620
 621	dev_dbg(dev, "TX From 0x%x, To 0x%x, Len %d, Flags %d, Reserved %d\n",
 622		src, dst, len, msg->flags, msg->reserved);
 623#if defined(CONFIG_DYNAMIC_DEBUG)
 624	dynamic_hex_dump("rpmsg_virtio TX: ", DUMP_PREFIX_NONE, 16, 1,
 625			 msg, sizeof(*msg) + len, true);
 626#endif
 627
 628	rpmsg_sg_init(&sg, msg, sizeof(*msg) + len);
 629
 630	mutex_lock(&vrp->tx_lock);
 631
 632	/* add message to the remote processor's virtqueue */
 633	err = virtqueue_add_outbuf(vrp->svq, &sg, 1, msg, GFP_KERNEL);
 634	if (err) {
 635		/*
 636		 * need to reclaim the buffer here, otherwise it's lost
 637		 * (memory won't leak, but rpmsg won't use it again for TX).
 638		 * this will wait for a buffer management overhaul.
 639		 */
 640		dev_err(dev, "virtqueue_add_outbuf failed: %d\n", err);
 641		goto out;
 642	}
 643
 644	/* tell the remote processor it has a pending message to read */
 645	virtqueue_kick(vrp->svq);
 646out:
 647	mutex_unlock(&vrp->tx_lock);
 648	return err;
 649}
 650
 651static int virtio_rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len)
 652{
 653	struct rpmsg_device *rpdev = ept->rpdev;
 654	u32 src = ept->addr, dst = rpdev->dst;
 655
 656	return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, true);
 657}
 658
 659static int virtio_rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len,
 660			       u32 dst)
 661{
 662	struct rpmsg_device *rpdev = ept->rpdev;
 663	u32 src = ept->addr;
 664
 665	return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, true);
 666}
 667
 668static int virtio_rpmsg_send_offchannel(struct rpmsg_endpoint *ept, u32 src,
 669					u32 dst, void *data, int len)
 670{
 671	struct rpmsg_device *rpdev = ept->rpdev;
 672
 673	return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, true);
 674}
 675
 676static int virtio_rpmsg_trysend(struct rpmsg_endpoint *ept, void *data, int len)
 677{
 678	struct rpmsg_device *rpdev = ept->rpdev;
 679	u32 src = ept->addr, dst = rpdev->dst;
 680
 681	return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, false);
 682}
 683
 684static int virtio_rpmsg_trysendto(struct rpmsg_endpoint *ept, void *data,
 685				  int len, u32 dst)
 686{
 687	struct rpmsg_device *rpdev = ept->rpdev;
 688	u32 src = ept->addr;
 689
 690	return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, false);
 691}
 692
 693static int virtio_rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src,
 694					   u32 dst, void *data, int len)
 695{
 696	struct rpmsg_device *rpdev = ept->rpdev;
 697
 698	return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, false);
 699}
 700
 701static ssize_t virtio_rpmsg_get_mtu(struct rpmsg_endpoint *ept)
 702{
 703	struct rpmsg_device *rpdev = ept->rpdev;
 704	struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
 705
 706	return vch->vrp->buf_size - sizeof(struct rpmsg_hdr);
 707}
 708
 709static int rpmsg_recv_single(struct virtproc_info *vrp, struct device *dev,
 710			     struct rpmsg_hdr *msg, unsigned int len)
 711{
 712	struct rpmsg_endpoint *ept;
 713	struct scatterlist sg;
 714	bool little_endian = virtio_is_little_endian(vrp->vdev);
 715	unsigned int msg_len = __rpmsg16_to_cpu(little_endian, msg->len);
 716	int err;
 717
 718	dev_dbg(dev, "From: 0x%x, To: 0x%x, Len: %d, Flags: %d, Reserved: %d\n",
 719		__rpmsg32_to_cpu(little_endian, msg->src),
 720		__rpmsg32_to_cpu(little_endian, msg->dst), msg_len,
 721		__rpmsg16_to_cpu(little_endian, msg->flags),
 722		__rpmsg32_to_cpu(little_endian, msg->reserved));
 723#if defined(CONFIG_DYNAMIC_DEBUG)
 724	dynamic_hex_dump("rpmsg_virtio RX: ", DUMP_PREFIX_NONE, 16, 1,
 725			 msg, sizeof(*msg) + msg_len, true);
 726#endif
 727
 728	/*
 729	 * We currently use fixed-sized buffers, so trivially sanitize
 730	 * the reported payload length.
 731	 */
 732	if (len > vrp->buf_size ||
 733	    msg_len > (len - sizeof(struct rpmsg_hdr))) {
 734		dev_warn(dev, "inbound msg too big: (%d, %d)\n", len, msg_len);
 735		return -EINVAL;
 736	}
 737
 738	/* use the dst addr to fetch the callback of the appropriate user */
 739	mutex_lock(&vrp->endpoints_lock);
 740
 741	ept = idr_find(&vrp->endpoints, __rpmsg32_to_cpu(little_endian, msg->dst));
 742
 743	/* let's make sure no one deallocates ept while we use it */
 744	if (ept)
 745		kref_get(&ept->refcount);
 746
 747	mutex_unlock(&vrp->endpoints_lock);
 748
 749	if (ept) {
 750		/* make sure ept->cb doesn't go away while we use it */
 751		mutex_lock(&ept->cb_lock);
 752
 753		if (ept->cb)
 754			ept->cb(ept->rpdev, msg->data, msg_len, ept->priv,
 755				__rpmsg32_to_cpu(little_endian, msg->src));
 756
 757		mutex_unlock(&ept->cb_lock);
 758
 759		/* farewell, ept, we don't need you anymore */
 760		kref_put(&ept->refcount, __ept_release);
 761	} else
 762		dev_warn_ratelimited(dev, "msg received with no recipient\n");
 763
 764	/* publish the real size of the buffer */
 765	rpmsg_sg_init(&sg, msg, vrp->buf_size);
 766
 767	/* add the buffer back to the remote processor's virtqueue */
 768	err = virtqueue_add_inbuf(vrp->rvq, &sg, 1, msg, GFP_KERNEL);
 769	if (err < 0) {
 770		dev_err(dev, "failed to add a virtqueue buffer: %d\n", err);
 771		return err;
 772	}
 773
 774	return 0;
 775}
 776
 777/* called when an rx buffer is used, and it's time to digest a message */
 778static void rpmsg_recv_done(struct virtqueue *rvq)
 779{
 780	struct virtproc_info *vrp = rvq->vdev->priv;
 781	struct device *dev = &rvq->vdev->dev;
 782	struct rpmsg_hdr *msg;
 783	unsigned int len, msgs_received = 0;
 784	int err;
 785
 786	msg = virtqueue_get_buf(rvq, &len);
 787	if (!msg) {
 788		dev_err(dev, "uhm, incoming signal, but no used buffer ?\n");
 789		return;
 790	}
 791
 792	while (msg) {
 793		err = rpmsg_recv_single(vrp, dev, msg, len);
 794		if (err)
 795			break;
 796
 797		msgs_received++;
 798
 799		msg = virtqueue_get_buf(rvq, &len);
 800	}
 801
 802	dev_dbg(dev, "Received %u messages\n", msgs_received);
 803
 804	/* tell the remote processor we added another available rx buffer */
 805	if (msgs_received)
 806		virtqueue_kick(vrp->rvq);
 807}
 808
 809/*
 810 * This is invoked whenever the remote processor completed processing
 811 * a TX msg we just sent it, and the buffer is put back to the used ring.
 812 *
 813 * Normally, though, we suppress this "tx complete" interrupt in order to
 814 * avoid the incurred overhead.
 815 */
 816static void rpmsg_xmit_done(struct virtqueue *svq)
 817{
 818	struct virtproc_info *vrp = svq->vdev->priv;
 819
 820	dev_dbg(&svq->vdev->dev, "%s\n", __func__);
 821
 822	/* wake up potential senders that are waiting for a tx buffer */
 823	wake_up_interruptible(&vrp->sendq);
 824}
 825
 826/*
 827 * Called to expose to user a /dev/rpmsg_ctrlX interface allowing to
 828 * create endpoint-to-endpoint communication without associated RPMsg channel.
 829 * The endpoints are rattached to the ctrldev RPMsg device.
 830 */
 831static struct rpmsg_device *rpmsg_virtio_add_ctrl_dev(struct virtio_device *vdev)
 832{
 833	struct virtproc_info *vrp = vdev->priv;
 834	struct virtio_rpmsg_channel *vch;
 835	struct rpmsg_device *rpdev_ctrl;
 836	int err = 0;
 837
 838	vch = kzalloc(sizeof(*vch), GFP_KERNEL);
 839	if (!vch)
 840		return ERR_PTR(-ENOMEM);
 841
 842	/* Link the channel to the vrp */
 843	vch->vrp = vrp;
 844
 845	/* Assign public information to the rpmsg_device */
 846	rpdev_ctrl = &vch->rpdev;
 847	rpdev_ctrl->ops = &virtio_rpmsg_ops;
 848
 849	rpdev_ctrl->dev.parent = &vrp->vdev->dev;
 850	rpdev_ctrl->dev.release = virtio_rpmsg_release_device;
 851	rpdev_ctrl->little_endian = virtio_is_little_endian(vrp->vdev);
 852
 853	err = rpmsg_ctrldev_register_device(rpdev_ctrl);
 854	if (err) {
 855		/* vch will be free in virtio_rpmsg_release_device() */
 856		return ERR_PTR(err);
 857	}
 858
 859	return rpdev_ctrl;
 860}
 861
 862static void rpmsg_virtio_del_ctrl_dev(struct rpmsg_device *rpdev_ctrl)
 863{
 864	if (!rpdev_ctrl)
 865		return;
 866	device_unregister(&rpdev_ctrl->dev);
 867}
 868
 869static int rpmsg_probe(struct virtio_device *vdev)
 870{
 871	vq_callback_t *vq_cbs[] = { rpmsg_recv_done, rpmsg_xmit_done };
 872	static const char * const names[] = { "input", "output" };
 
 
 873	struct virtqueue *vqs[2];
 874	struct virtproc_info *vrp;
 875	struct virtio_rpmsg_channel *vch = NULL;
 876	struct rpmsg_device *rpdev_ns, *rpdev_ctrl;
 877	void *bufs_va;
 878	int err = 0, i;
 879	size_t total_buf_space;
 880	bool notify;
 881
 882	vrp = kzalloc(sizeof(*vrp), GFP_KERNEL);
 883	if (!vrp)
 884		return -ENOMEM;
 885
 886	vrp->vdev = vdev;
 887
 888	idr_init(&vrp->endpoints);
 889	mutex_init(&vrp->endpoints_lock);
 890	mutex_init(&vrp->tx_lock);
 891	init_waitqueue_head(&vrp->sendq);
 892
 893	/* We expect two virtqueues, rx and tx (and in this order) */
 894	err = virtio_find_vqs(vdev, 2, vqs, vq_cbs, names, NULL);
 895	if (err)
 896		goto free_vrp;
 897
 898	vrp->rvq = vqs[0];
 899	vrp->svq = vqs[1];
 900
 901	/* we expect symmetric tx/rx vrings */
 902	WARN_ON(virtqueue_get_vring_size(vrp->rvq) !=
 903		virtqueue_get_vring_size(vrp->svq));
 904
 905	/* we need less buffers if vrings are small */
 906	if (virtqueue_get_vring_size(vrp->rvq) < MAX_RPMSG_NUM_BUFS / 2)
 907		vrp->num_bufs = virtqueue_get_vring_size(vrp->rvq) * 2;
 908	else
 909		vrp->num_bufs = MAX_RPMSG_NUM_BUFS;
 910
 911	vrp->buf_size = MAX_RPMSG_BUF_SIZE;
 912
 913	total_buf_space = vrp->num_bufs * vrp->buf_size;
 914
 915	/* allocate coherent memory for the buffers */
 916	bufs_va = dma_alloc_coherent(vdev->dev.parent,
 917				     total_buf_space, &vrp->bufs_dma,
 918				     GFP_KERNEL);
 919	if (!bufs_va) {
 920		err = -ENOMEM;
 921		goto vqs_del;
 922	}
 923
 924	dev_dbg(&vdev->dev, "buffers: va %pK, dma %pad\n",
 925		bufs_va, &vrp->bufs_dma);
 926
 927	/* half of the buffers is dedicated for RX */
 928	vrp->rbufs = bufs_va;
 929
 930	/* and half is dedicated for TX */
 931	vrp->sbufs = bufs_va + total_buf_space / 2;
 932
 933	/* set up the receive buffers */
 934	for (i = 0; i < vrp->num_bufs / 2; i++) {
 935		struct scatterlist sg;
 936		void *cpu_addr = vrp->rbufs + i * vrp->buf_size;
 937
 938		rpmsg_sg_init(&sg, cpu_addr, vrp->buf_size);
 939
 940		err = virtqueue_add_inbuf(vrp->rvq, &sg, 1, cpu_addr,
 941					  GFP_KERNEL);
 942		WARN_ON(err); /* sanity check; this can't really happen */
 943	}
 944
 945	/* suppress "tx-complete" interrupts */
 946	virtqueue_disable_cb(vrp->svq);
 947
 948	vdev->priv = vrp;
 949
 950	rpdev_ctrl = rpmsg_virtio_add_ctrl_dev(vdev);
 951	if (IS_ERR(rpdev_ctrl)) {
 952		err = PTR_ERR(rpdev_ctrl);
 953		goto free_coherent;
 954	}
 955
 956	/* if supported by the remote processor, enable the name service */
 957	if (virtio_has_feature(vdev, VIRTIO_RPMSG_F_NS)) {
 958		vch = kzalloc(sizeof(*vch), GFP_KERNEL);
 959		if (!vch) {
 960			err = -ENOMEM;
 961			goto free_ctrldev;
 962		}
 963
 964		/* Link the channel to our vrp */
 965		vch->vrp = vrp;
 966
 967		/* Assign public information to the rpmsg_device */
 968		rpdev_ns = &vch->rpdev;
 969		rpdev_ns->ops = &virtio_rpmsg_ops;
 970		rpdev_ns->little_endian = virtio_is_little_endian(vrp->vdev);
 971
 972		rpdev_ns->dev.parent = &vrp->vdev->dev;
 973		rpdev_ns->dev.release = virtio_rpmsg_release_device;
 974
 975		err = rpmsg_ns_register_device(rpdev_ns);
 976		if (err)
 977			/* vch will be free in virtio_rpmsg_release_device() */
 978			goto free_ctrldev;
 979	}
 980
 981	/*
 982	 * Prepare to kick but don't notify yet - we can't do this before
 983	 * device is ready.
 984	 */
 985	notify = virtqueue_kick_prepare(vrp->rvq);
 986
 987	/* From this point on, we can notify and get callbacks. */
 988	virtio_device_ready(vdev);
 989
 990	/* tell the remote processor it can start sending messages */
 991	/*
 992	 * this might be concurrent with callbacks, but we are only
 993	 * doing notify, not a full kick here, so that's ok.
 994	 */
 995	if (notify)
 996		virtqueue_notify(vrp->rvq);
 997
 998	dev_info(&vdev->dev, "rpmsg host is online\n");
 999
1000	return 0;
1001
1002free_ctrldev:
1003	rpmsg_virtio_del_ctrl_dev(rpdev_ctrl);
1004free_coherent:
1005	dma_free_coherent(vdev->dev.parent, total_buf_space,
1006			  bufs_va, vrp->bufs_dma);
1007vqs_del:
1008	vdev->config->del_vqs(vrp->vdev);
1009free_vrp:
1010	kfree(vrp);
1011	return err;
1012}
1013
1014static int rpmsg_remove_device(struct device *dev, void *data)
1015{
1016	device_unregister(dev);
1017
1018	return 0;
1019}
1020
1021static void rpmsg_remove(struct virtio_device *vdev)
1022{
1023	struct virtproc_info *vrp = vdev->priv;
1024	size_t total_buf_space = vrp->num_bufs * vrp->buf_size;
1025	int ret;
1026
1027	virtio_reset_device(vdev);
1028
1029	ret = device_for_each_child(&vdev->dev, NULL, rpmsg_remove_device);
1030	if (ret)
1031		dev_warn(&vdev->dev, "can't remove rpmsg device: %d\n", ret);
1032
1033	idr_destroy(&vrp->endpoints);
1034
1035	vdev->config->del_vqs(vrp->vdev);
1036
1037	dma_free_coherent(vdev->dev.parent, total_buf_space,
1038			  vrp->rbufs, vrp->bufs_dma);
1039
1040	kfree(vrp);
1041}
1042
1043static struct virtio_device_id id_table[] = {
1044	{ VIRTIO_ID_RPMSG, VIRTIO_DEV_ANY_ID },
1045	{ 0 },
1046};
1047
1048static unsigned int features[] = {
1049	VIRTIO_RPMSG_F_NS,
1050};
1051
1052static struct virtio_driver virtio_ipc_driver = {
1053	.feature_table	= features,
1054	.feature_table_size = ARRAY_SIZE(features),
1055	.driver.name	= KBUILD_MODNAME,
1056	.driver.owner	= THIS_MODULE,
1057	.id_table	= id_table,
1058	.probe		= rpmsg_probe,
1059	.remove		= rpmsg_remove,
1060};
1061
1062static int __init rpmsg_init(void)
1063{
1064	int ret;
1065
1066	ret = register_virtio_driver(&virtio_ipc_driver);
1067	if (ret)
1068		pr_err("failed to register virtio driver: %d\n", ret);
1069
1070	return ret;
1071}
1072subsys_initcall(rpmsg_init);
1073
1074static void __exit rpmsg_fini(void)
1075{
1076	unregister_virtio_driver(&virtio_ipc_driver);
1077}
1078module_exit(rpmsg_fini);
1079
1080MODULE_DEVICE_TABLE(virtio, id_table);
1081MODULE_DESCRIPTION("Virtio-based remote processor messaging bus");
1082MODULE_LICENSE("GPL v2");