virtio_rpmsg_bus.c

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