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/of_device.h>
21#include <linux/rpmsg.h>
22#include <linux/scatterlist.h>
23#include <linux/slab.h>
24#include <linux/sched.h>
25#include <linux/virtio.h>
26#include <linux/virtio_ids.h>
27#include <linux/virtio_config.h>
28#include <linux/wait.h>
29
30#include "rpmsg_internal.h"
31
32/**
33 * struct virtproc_info - virtual remote processor state
34 * @vdev: the virtio device
35 * @rvq: rx virtqueue
36 * @svq: tx virtqueue
37 * @rbufs: kernel address of rx buffers
38 * @sbufs: kernel address of tx buffers
39 * @num_bufs: total number of buffers for rx and tx
40 * @buf_size: size of one rx or tx buffer
41 * @last_sbuf: index of last tx buffer used
42 * @bufs_dma: dma base addr of the buffers
43 * @tx_lock: protects svq, sbufs and sleepers, to allow concurrent senders.
44 * sending a message might require waking up a dozing remote
45 * processor, which involves sleeping, hence the mutex.
46 * @endpoints: idr of local endpoints, allows fast retrieval
47 * @endpoints_lock: lock of the endpoints set
48 * @sendq: wait queue of sending contexts waiting for a tx buffers
49 * @sleepers: number of senders that are waiting for a tx buffer
50 * @ns_ept: the bus's name service endpoint
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 struct rpmsg_endpoint *ns_ept;
70};
71
72/* The feature bitmap for virtio rpmsg */
73#define VIRTIO_RPMSG_F_NS 0 /* RP supports name service notifications */
74
75/**
76 * struct rpmsg_hdr - common header for all rpmsg messages
77 * @src: source address
78 * @dst: destination address
79 * @reserved: reserved for future use
80 * @len: length of payload (in bytes)
81 * @flags: message flags
82 * @data: @len bytes of message payload data
83 *
84 * Every message sent(/received) on the rpmsg bus begins with this header.
85 */
86struct rpmsg_hdr {
87 u32 src;
88 u32 dst;
89 u32 reserved;
90 u16 len;
91 u16 flags;
92 u8 data[0];
93} __packed;
94
95/**
96 * struct rpmsg_ns_msg - dynamic name service announcement message
97 * @name: name of remote service that is published
98 * @addr: address of remote service that is published
99 * @flags: indicates whether service is created or destroyed
100 *
101 * This message is sent across to publish a new service, or announce
102 * about its removal. When we receive these messages, an appropriate
103 * rpmsg channel (i.e device) is created/destroyed. In turn, the ->probe()
104 * or ->remove() handler of the appropriate rpmsg driver will be invoked
105 * (if/as-soon-as one is registered).
106 */
107struct rpmsg_ns_msg {
108 char name[RPMSG_NAME_SIZE];
109 u32 addr;
110 u32 flags;
111} __packed;
112
113/**
114 * enum rpmsg_ns_flags - dynamic name service announcement flags
115 *
116 * @RPMSG_NS_CREATE: a new remote service was just created
117 * @RPMSG_NS_DESTROY: a known remote service was just destroyed
118 */
119enum rpmsg_ns_flags {
120 RPMSG_NS_CREATE = 0,
121 RPMSG_NS_DESTROY = 1,
122};
123
124/**
125 * @vrp: the remote processor this channel belongs to
126 */
127struct virtio_rpmsg_channel {
128 struct rpmsg_device rpdev;
129
130 struct virtproc_info *vrp;
131};
132
133#define to_virtio_rpmsg_channel(_rpdev) \
134 container_of(_rpdev, struct virtio_rpmsg_channel, rpdev)
135
136/*
137 * We're allocating buffers of 512 bytes each for communications. The
138 * number of buffers will be computed from the number of buffers supported
139 * by the vring, upto a maximum of 512 buffers (256 in each direction).
140 *
141 * Each buffer will have 16 bytes for the msg header and 496 bytes for
142 * the payload.
143 *
144 * This will utilize a maximum total space of 256KB for the buffers.
145 *
146 * We might also want to add support for user-provided buffers in time.
147 * This will allow bigger buffer size flexibility, and can also be used
148 * to achieve zero-copy messaging.
149 *
150 * Note that these numbers are purely a decision of this driver - we
151 * can change this without changing anything in the firmware of the remote
152 * processor.
153 */
154#define MAX_RPMSG_NUM_BUFS (512)
155#define MAX_RPMSG_BUF_SIZE (512)
156
157/*
158 * Local addresses are dynamically allocated on-demand.
159 * We do not dynamically assign addresses from the low 1024 range,
160 * in order to reserve that address range for predefined services.
161 */
162#define RPMSG_RESERVED_ADDRESSES (1024)
163
164/* Address 53 is reserved for advertising remote services */
165#define RPMSG_NS_ADDR (53)
166
167static void virtio_rpmsg_destroy_ept(struct rpmsg_endpoint *ept);
168static int virtio_rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len);
169static int virtio_rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len,
170 u32 dst);
171static int virtio_rpmsg_send_offchannel(struct rpmsg_endpoint *ept, u32 src,
172 u32 dst, void *data, int len);
173static int virtio_rpmsg_trysend(struct rpmsg_endpoint *ept, void *data, int len);
174static int virtio_rpmsg_trysendto(struct rpmsg_endpoint *ept, void *data,
175 int len, u32 dst);
176static int virtio_rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src,
177 u32 dst, void *data, int len);
178
179static const struct rpmsg_endpoint_ops virtio_endpoint_ops = {
180 .destroy_ept = virtio_rpmsg_destroy_ept,
181 .send = virtio_rpmsg_send,
182 .sendto = virtio_rpmsg_sendto,
183 .send_offchannel = virtio_rpmsg_send_offchannel,
184 .trysend = virtio_rpmsg_trysend,
185 .trysendto = virtio_rpmsg_trysendto,
186 .trysend_offchannel = virtio_rpmsg_trysend_offchannel,
187};
188
189/**
190 * rpmsg_sg_init - initialize scatterlist according to cpu address location
191 * @sg: scatterlist to fill
192 * @cpu_addr: virtual address of the buffer
193 * @len: buffer length
194 *
195 * An internal function filling scatterlist according to virtual address
196 * location (in vmalloc or in kernel).
197 */
198static void
199rpmsg_sg_init(struct scatterlist *sg, void *cpu_addr, unsigned int len)
200{
201 if (is_vmalloc_addr(cpu_addr)) {
202 sg_init_table(sg, 1);
203 sg_set_page(sg, vmalloc_to_page(cpu_addr), len,
204 offset_in_page(cpu_addr));
205 } else {
206 WARN_ON(!virt_addr_valid(cpu_addr));
207 sg_init_one(sg, cpu_addr, len);
208 }
209}
210
211/**
212 * __ept_release() - deallocate an rpmsg endpoint
213 * @kref: the ept's reference count
214 *
215 * This function deallocates an ept, and is invoked when its @kref refcount
216 * drops to zero.
217 *
218 * Never invoke this function directly!
219 */
220static void __ept_release(struct kref *kref)
221{
222 struct rpmsg_endpoint *ept = container_of(kref, struct rpmsg_endpoint,
223 refcount);
224 /*
225 * At this point no one holds a reference to ept anymore,
226 * so we can directly free it
227 */
228 kfree(ept);
229}
230
231/* for more info, see below documentation of rpmsg_create_ept() */
232static struct rpmsg_endpoint *__rpmsg_create_ept(struct virtproc_info *vrp,
233 struct rpmsg_device *rpdev,
234 rpmsg_rx_cb_t cb,
235 void *priv, u32 addr)
236{
237 int id_min, id_max, id;
238 struct rpmsg_endpoint *ept;
239 struct device *dev = rpdev ? &rpdev->dev : &vrp->vdev->dev;
240
241 ept = kzalloc(sizeof(*ept), GFP_KERNEL);
242 if (!ept)
243 return NULL;
244
245 kref_init(&ept->refcount);
246 mutex_init(&ept->cb_lock);
247
248 ept->rpdev = rpdev;
249 ept->cb = cb;
250 ept->priv = priv;
251 ept->ops = &virtio_endpoint_ops;
252
253 /* do we need to allocate a local address ? */
254 if (addr == RPMSG_ADDR_ANY) {
255 id_min = RPMSG_RESERVED_ADDRESSES;
256 id_max = 0;
257 } else {
258 id_min = addr;
259 id_max = addr + 1;
260 }
261
262 mutex_lock(&vrp->endpoints_lock);
263
264 /* bind the endpoint to an rpmsg address (and allocate one if needed) */
265 id = idr_alloc(&vrp->endpoints, ept, id_min, id_max, GFP_KERNEL);
266 if (id < 0) {
267 dev_err(dev, "idr_alloc failed: %d\n", id);
268 goto free_ept;
269 }
270 ept->addr = id;
271
272 mutex_unlock(&vrp->endpoints_lock);
273
274 return ept;
275
276free_ept:
277 mutex_unlock(&vrp->endpoints_lock);
278 kref_put(&ept->refcount, __ept_release);
279 return NULL;
280}
281
282static struct rpmsg_endpoint *virtio_rpmsg_create_ept(struct rpmsg_device *rpdev,
283 rpmsg_rx_cb_t cb,
284 void *priv,
285 struct rpmsg_channel_info chinfo)
286{
287 struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
288
289 return __rpmsg_create_ept(vch->vrp, rpdev, cb, priv, chinfo.src);
290}
291
292/**
293 * __rpmsg_destroy_ept() - destroy an existing rpmsg endpoint
294 * @vrp: virtproc which owns this ept
295 * @ept: endpoing to destroy
296 *
297 * An internal function which destroy an ept without assuming it is
298 * bound to an rpmsg channel. This is needed for handling the internal
299 * name service endpoint, which isn't bound to an rpmsg channel.
300 * See also __rpmsg_create_ept().
301 */
302static void
303__rpmsg_destroy_ept(struct virtproc_info *vrp, struct rpmsg_endpoint *ept)
304{
305 /* make sure new inbound messages can't find this ept anymore */
306 mutex_lock(&vrp->endpoints_lock);
307 idr_remove(&vrp->endpoints, ept->addr);
308 mutex_unlock(&vrp->endpoints_lock);
309
310 /* make sure in-flight inbound messages won't invoke cb anymore */
311 mutex_lock(&ept->cb_lock);
312 ept->cb = NULL;
313 mutex_unlock(&ept->cb_lock);
314
315 kref_put(&ept->refcount, __ept_release);
316}
317
318static void virtio_rpmsg_destroy_ept(struct rpmsg_endpoint *ept)
319{
320 struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(ept->rpdev);
321
322 __rpmsg_destroy_ept(vch->vrp, ept);
323}
324
325static int virtio_rpmsg_announce_create(struct rpmsg_device *rpdev)
326{
327 struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
328 struct virtproc_info *vrp = vch->vrp;
329 struct device *dev = &rpdev->dev;
330 int err = 0;
331
332 /* need to tell remote processor's name service about this channel ? */
333 if (rpdev->announce && rpdev->ept &&
334 virtio_has_feature(vrp->vdev, VIRTIO_RPMSG_F_NS)) {
335 struct rpmsg_ns_msg nsm;
336
337 strncpy(nsm.name, rpdev->id.name, RPMSG_NAME_SIZE);
338 nsm.addr = rpdev->ept->addr;
339 nsm.flags = RPMSG_NS_CREATE;
340
341 err = rpmsg_sendto(rpdev->ept, &nsm, sizeof(nsm), RPMSG_NS_ADDR);
342 if (err)
343 dev_err(dev, "failed to announce service %d\n", err);
344 }
345
346 return err;
347}
348
349static int virtio_rpmsg_announce_destroy(struct rpmsg_device *rpdev)
350{
351 struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
352 struct virtproc_info *vrp = vch->vrp;
353 struct device *dev = &rpdev->dev;
354 int err = 0;
355
356 /* tell remote processor's name service we're removing this channel */
357 if (rpdev->announce && rpdev->ept &&
358 virtio_has_feature(vrp->vdev, VIRTIO_RPMSG_F_NS)) {
359 struct rpmsg_ns_msg nsm;
360
361 strncpy(nsm.name, rpdev->id.name, RPMSG_NAME_SIZE);
362 nsm.addr = rpdev->ept->addr;
363 nsm.flags = RPMSG_NS_DESTROY;
364
365 err = rpmsg_sendto(rpdev->ept, &nsm, sizeof(nsm), RPMSG_NS_ADDR);
366 if (err)
367 dev_err(dev, "failed to announce service %d\n", err);
368 }
369
370 return err;
371}
372
373static const struct rpmsg_device_ops virtio_rpmsg_ops = {
374 .create_ept = virtio_rpmsg_create_ept,
375 .announce_create = virtio_rpmsg_announce_create,
376 .announce_destroy = virtio_rpmsg_announce_destroy,
377};
378
379static void virtio_rpmsg_release_device(struct device *dev)
380{
381 struct rpmsg_device *rpdev = to_rpmsg_device(dev);
382 struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
383
384 kfree(vch);
385}
386
387/*
388 * create an rpmsg channel using its name and address info.
389 * this function will be used to create both static and dynamic
390 * channels.
391 */
392static struct rpmsg_device *rpmsg_create_channel(struct virtproc_info *vrp,
393 struct rpmsg_channel_info *chinfo)
394{
395 struct virtio_rpmsg_channel *vch;
396 struct rpmsg_device *rpdev;
397 struct device *tmp, *dev = &vrp->vdev->dev;
398 int ret;
399
400 /* make sure a similar channel doesn't already exist */
401 tmp = rpmsg_find_device(dev, chinfo);
402 if (tmp) {
403 /* decrement the matched device's refcount back */
404 put_device(tmp);
405 dev_err(dev, "channel %s:%x:%x already exist\n",
406 chinfo->name, chinfo->src, chinfo->dst);
407 return NULL;
408 }
409
410 vch = kzalloc(sizeof(*vch), GFP_KERNEL);
411 if (!vch)
412 return NULL;
413
414 /* Link the channel to our vrp */
415 vch->vrp = vrp;
416
417 /* Assign public information to the rpmsg_device */
418 rpdev = &vch->rpdev;
419 rpdev->src = chinfo->src;
420 rpdev->dst = chinfo->dst;
421 rpdev->ops = &virtio_rpmsg_ops;
422
423 /*
424 * rpmsg server channels has predefined local address (for now),
425 * and their existence needs to be announced remotely
426 */
427 rpdev->announce = rpdev->src != RPMSG_ADDR_ANY;
428
429 strncpy(rpdev->id.name, chinfo->name, RPMSG_NAME_SIZE);
430
431 rpdev->dev.parent = &vrp->vdev->dev;
432 rpdev->dev.release = virtio_rpmsg_release_device;
433 ret = rpmsg_register_device(rpdev);
434 if (ret)
435 return NULL;
436
437 return rpdev;
438}
439
440/* super simple buffer "allocator" that is just enough for now */
441static void *get_a_tx_buf(struct virtproc_info *vrp)
442{
443 unsigned int len;
444 void *ret;
445
446 /* support multiple concurrent senders */
447 mutex_lock(&vrp->tx_lock);
448
449 /*
450 * either pick the next unused tx buffer
451 * (half of our buffers are used for sending messages)
452 */
453 if (vrp->last_sbuf < vrp->num_bufs / 2)
454 ret = vrp->sbufs + vrp->buf_size * vrp->last_sbuf++;
455 /* or recycle a used one */
456 else
457 ret = virtqueue_get_buf(vrp->svq, &len);
458
459 mutex_unlock(&vrp->tx_lock);
460
461 return ret;
462}
463
464/**
465 * rpmsg_upref_sleepers() - enable "tx-complete" interrupts, if needed
466 * @vrp: virtual remote processor state
467 *
468 * This function is called before a sender is blocked, waiting for
469 * a tx buffer to become available.
470 *
471 * If we already have blocking senders, this function merely increases
472 * the "sleepers" reference count, and exits.
473 *
474 * Otherwise, if this is the first sender to block, we also enable
475 * virtio's tx callbacks, so we'd be immediately notified when a tx
476 * buffer is consumed (we rely on virtio's tx callback in order
477 * to wake up sleeping senders as soon as a tx buffer is used by the
478 * remote processor).
479 */
480static void rpmsg_upref_sleepers(struct virtproc_info *vrp)
481{
482 /* support multiple concurrent senders */
483 mutex_lock(&vrp->tx_lock);
484
485 /* are we the first sleeping context waiting for tx buffers ? */
486 if (atomic_inc_return(&vrp->sleepers) == 1)
487 /* enable "tx-complete" interrupts before dozing off */
488 virtqueue_enable_cb(vrp->svq);
489
490 mutex_unlock(&vrp->tx_lock);
491}
492
493/**
494 * rpmsg_downref_sleepers() - disable "tx-complete" interrupts, if needed
495 * @vrp: virtual remote processor state
496 *
497 * This function is called after a sender, that waited for a tx buffer
498 * to become available, is unblocked.
499 *
500 * If we still have blocking senders, this function merely decreases
501 * the "sleepers" reference count, and exits.
502 *
503 * Otherwise, if there are no more blocking senders, we also disable
504 * virtio's tx callbacks, to avoid the overhead incurred with handling
505 * those (now redundant) interrupts.
506 */
507static void rpmsg_downref_sleepers(struct virtproc_info *vrp)
508{
509 /* support multiple concurrent senders */
510 mutex_lock(&vrp->tx_lock);
511
512 /* are we the last sleeping context waiting for tx buffers ? */
513 if (atomic_dec_and_test(&vrp->sleepers))
514 /* disable "tx-complete" interrupts */
515 virtqueue_disable_cb(vrp->svq);
516
517 mutex_unlock(&vrp->tx_lock);
518}
519
520/**
521 * rpmsg_send_offchannel_raw() - send a message across to the remote processor
522 * @rpdev: the rpmsg channel
523 * @src: source address
524 * @dst: destination address
525 * @data: payload of message
526 * @len: length of payload
527 * @wait: indicates whether caller should block in case no TX buffers available
528 *
529 * This function is the base implementation for all of the rpmsg sending API.
530 *
531 * It will send @data of length @len to @dst, and say it's from @src. The
532 * message will be sent to the remote processor which the @rpdev channel
533 * belongs to.
534 *
535 * The message is sent using one of the TX buffers that are available for
536 * communication with this remote processor.
537 *
538 * If @wait is true, the caller will be blocked until either a TX buffer is
539 * available, or 15 seconds elapses (we don't want callers to
540 * sleep indefinitely due to misbehaving remote processors), and in that
541 * case -ERESTARTSYS is returned. The number '15' itself was picked
542 * arbitrarily; there's little point in asking drivers to provide a timeout
543 * value themselves.
544 *
545 * Otherwise, if @wait is false, and there are no TX buffers available,
546 * the function will immediately fail, and -ENOMEM will be returned.
547 *
548 * Normally drivers shouldn't use this function directly; instead, drivers
549 * should use the appropriate rpmsg_{try}send{to, _offchannel} API
550 * (see include/linux/rpmsg.h).
551 *
552 * Returns 0 on success and an appropriate error value on failure.
553 */
554static int rpmsg_send_offchannel_raw(struct rpmsg_device *rpdev,
555 u32 src, u32 dst,
556 void *data, int len, bool wait)
557{
558 struct virtio_rpmsg_channel *vch = to_virtio_rpmsg_channel(rpdev);
559 struct virtproc_info *vrp = vch->vrp;
560 struct device *dev = &rpdev->dev;
561 struct scatterlist sg;
562 struct rpmsg_hdr *msg;
563 int err;
564
565 /* bcasting isn't allowed */
566 if (src == RPMSG_ADDR_ANY || dst == RPMSG_ADDR_ANY) {
567 dev_err(dev, "invalid addr (src 0x%x, dst 0x%x)\n", src, dst);
568 return -EINVAL;
569 }
570
571 /*
572 * We currently use fixed-sized buffers, and therefore the payload
573 * length is limited.
574 *
575 * One of the possible improvements here is either to support
576 * user-provided buffers (and then we can also support zero-copy
577 * messaging), or to improve the buffer allocator, to support
578 * variable-length buffer sizes.
579 */
580 if (len > vrp->buf_size - sizeof(struct rpmsg_hdr)) {
581 dev_err(dev, "message is too big (%d)\n", len);
582 return -EMSGSIZE;
583 }
584
585 /* grab a buffer */
586 msg = get_a_tx_buf(vrp);
587 if (!msg && !wait)
588 return -ENOMEM;
589
590 /* no free buffer ? wait for one (but bail after 15 seconds) */
591 while (!msg) {
592 /* enable "tx-complete" interrupts, if not already enabled */
593 rpmsg_upref_sleepers(vrp);
594
595 /*
596 * sleep until a free buffer is available or 15 secs elapse.
597 * the timeout period is not configurable because there's
598 * little point in asking drivers to specify that.
599 * if later this happens to be required, it'd be easy to add.
600 */
601 err = wait_event_interruptible_timeout(vrp->sendq,
602 (msg = get_a_tx_buf(vrp)),
603 msecs_to_jiffies(15000));
604
605 /* disable "tx-complete" interrupts if we're the last sleeper */
606 rpmsg_downref_sleepers(vrp);
607
608 /* timeout ? */
609 if (!err) {
610 dev_err(dev, "timeout waiting for a tx buffer\n");
611 return -ERESTARTSYS;
612 }
613 }
614
615 msg->len = len;
616 msg->flags = 0;
617 msg->src = src;
618 msg->dst = dst;
619 msg->reserved = 0;
620 memcpy(msg->data, data, len);
621
622 dev_dbg(dev, "TX From 0x%x, To 0x%x, Len %d, Flags %d, Reserved %d\n",
623 msg->src, msg->dst, msg->len, msg->flags, msg->reserved);
624#if defined(CONFIG_DYNAMIC_DEBUG)
625 dynamic_hex_dump("rpmsg_virtio TX: ", DUMP_PREFIX_NONE, 16, 1,
626 msg, sizeof(*msg) + msg->len, true);
627#endif
628
629 rpmsg_sg_init(&sg, msg, sizeof(*msg) + len);
630
631 mutex_lock(&vrp->tx_lock);
632
633 /* add message to the remote processor's virtqueue */
634 err = virtqueue_add_outbuf(vrp->svq, &sg, 1, msg, GFP_KERNEL);
635 if (err) {
636 /*
637 * need to reclaim the buffer here, otherwise it's lost
638 * (memory won't leak, but rpmsg won't use it again for TX).
639 * this will wait for a buffer management overhaul.
640 */
641 dev_err(dev, "virtqueue_add_outbuf failed: %d\n", err);
642 goto out;
643 }
644
645 /* tell the remote processor it has a pending message to read */
646 virtqueue_kick(vrp->svq);
647out:
648 mutex_unlock(&vrp->tx_lock);
649 return err;
650}
651
652static int virtio_rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len)
653{
654 struct rpmsg_device *rpdev = ept->rpdev;
655 u32 src = ept->addr, dst = rpdev->dst;
656
657 return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, true);
658}
659
660static int virtio_rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len,
661 u32 dst)
662{
663 struct rpmsg_device *rpdev = ept->rpdev;
664 u32 src = ept->addr;
665
666 return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, true);
667}
668
669static int virtio_rpmsg_send_offchannel(struct rpmsg_endpoint *ept, u32 src,
670 u32 dst, void *data, int len)
671{
672 struct rpmsg_device *rpdev = ept->rpdev;
673
674 return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, true);
675}
676
677static int virtio_rpmsg_trysend(struct rpmsg_endpoint *ept, void *data, int len)
678{
679 struct rpmsg_device *rpdev = ept->rpdev;
680 u32 src = ept->addr, dst = rpdev->dst;
681
682 return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, false);
683}
684
685static int virtio_rpmsg_trysendto(struct rpmsg_endpoint *ept, void *data,
686 int len, u32 dst)
687{
688 struct rpmsg_device *rpdev = ept->rpdev;
689 u32 src = ept->addr;
690
691 return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, false);
692}
693
694static int virtio_rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src,
695 u32 dst, void *data, int len)
696{
697 struct rpmsg_device *rpdev = ept->rpdev;
698
699 return rpmsg_send_offchannel_raw(rpdev, src, dst, data, len, false);
700}
701
702static int rpmsg_recv_single(struct virtproc_info *vrp, struct device *dev,
703 struct rpmsg_hdr *msg, unsigned int len)
704{
705 struct rpmsg_endpoint *ept;
706 struct scatterlist sg;
707 int err;
708
709 dev_dbg(dev, "From: 0x%x, To: 0x%x, Len: %d, Flags: %d, Reserved: %d\n",
710 msg->src, msg->dst, msg->len, msg->flags, msg->reserved);
711#if defined(CONFIG_DYNAMIC_DEBUG)
712 dynamic_hex_dump("rpmsg_virtio RX: ", DUMP_PREFIX_NONE, 16, 1,
713 msg, sizeof(*msg) + msg->len, true);
714#endif
715
716 /*
717 * We currently use fixed-sized buffers, so trivially sanitize
718 * the reported payload length.
719 */
720 if (len > vrp->buf_size ||
721 msg->len > (len - sizeof(struct rpmsg_hdr))) {
722 dev_warn(dev, "inbound msg too big: (%d, %d)\n", len, msg->len);
723 return -EINVAL;
724 }
725
726 /* use the dst addr to fetch the callback of the appropriate user */
727 mutex_lock(&vrp->endpoints_lock);
728
729 ept = idr_find(&vrp->endpoints, msg->dst);
730
731 /* let's make sure no one deallocates ept while we use it */
732 if (ept)
733 kref_get(&ept->refcount);
734
735 mutex_unlock(&vrp->endpoints_lock);
736
737 if (ept) {
738 /* make sure ept->cb doesn't go away while we use it */
739 mutex_lock(&ept->cb_lock);
740
741 if (ept->cb)
742 ept->cb(ept->rpdev, msg->data, msg->len, ept->priv,
743 msg->src);
744
745 mutex_unlock(&ept->cb_lock);
746
747 /* farewell, ept, we don't need you anymore */
748 kref_put(&ept->refcount, __ept_release);
749 } else
750 dev_warn(dev, "msg received with no recipient\n");
751
752 /* publish the real size of the buffer */
753 rpmsg_sg_init(&sg, msg, vrp->buf_size);
754
755 /* add the buffer back to the remote processor's virtqueue */
756 err = virtqueue_add_inbuf(vrp->rvq, &sg, 1, msg, GFP_KERNEL);
757 if (err < 0) {
758 dev_err(dev, "failed to add a virtqueue buffer: %d\n", err);
759 return err;
760 }
761
762 return 0;
763}
764
765/* called when an rx buffer is used, and it's time to digest a message */
766static void rpmsg_recv_done(struct virtqueue *rvq)
767{
768 struct virtproc_info *vrp = rvq->vdev->priv;
769 struct device *dev = &rvq->vdev->dev;
770 struct rpmsg_hdr *msg;
771 unsigned int len, msgs_received = 0;
772 int err;
773
774 msg = virtqueue_get_buf(rvq, &len);
775 if (!msg) {
776 dev_err(dev, "uhm, incoming signal, but no used buffer ?\n");
777 return;
778 }
779
780 while (msg) {
781 err = rpmsg_recv_single(vrp, dev, msg, len);
782 if (err)
783 break;
784
785 msgs_received++;
786
787 msg = virtqueue_get_buf(rvq, &len);
788 }
789
790 dev_dbg(dev, "Received %u messages\n", msgs_received);
791
792 /* tell the remote processor we added another available rx buffer */
793 if (msgs_received)
794 virtqueue_kick(vrp->rvq);
795}
796
797/*
798 * This is invoked whenever the remote processor completed processing
799 * a TX msg we just sent it, and the buffer is put back to the used ring.
800 *
801 * Normally, though, we suppress this "tx complete" interrupt in order to
802 * avoid the incurred overhead.
803 */
804static void rpmsg_xmit_done(struct virtqueue *svq)
805{
806 struct virtproc_info *vrp = svq->vdev->priv;
807
808 dev_dbg(&svq->vdev->dev, "%s\n", __func__);
809
810 /* wake up potential senders that are waiting for a tx buffer */
811 wake_up_interruptible(&vrp->sendq);
812}
813
814/* invoked when a name service announcement arrives */
815static int rpmsg_ns_cb(struct rpmsg_device *rpdev, void *data, int len,
816 void *priv, u32 src)
817{
818 struct rpmsg_ns_msg *msg = data;
819 struct rpmsg_device *newch;
820 struct rpmsg_channel_info chinfo;
821 struct virtproc_info *vrp = priv;
822 struct device *dev = &vrp->vdev->dev;
823 int ret;
824
825#if defined(CONFIG_DYNAMIC_DEBUG)
826 dynamic_hex_dump("NS announcement: ", DUMP_PREFIX_NONE, 16, 1,
827 data, len, true);
828#endif
829
830 if (len != sizeof(*msg)) {
831 dev_err(dev, "malformed ns msg (%d)\n", len);
832 return -EINVAL;
833 }
834
835 /*
836 * the name service ept does _not_ belong to a real rpmsg channel,
837 * and is handled by the rpmsg bus itself.
838 * for sanity reasons, make sure a valid rpdev has _not_ sneaked
839 * in somehow.
840 */
841 if (rpdev) {
842 dev_err(dev, "anomaly: ns ept has an rpdev handle\n");
843 return -EINVAL;
844 }
845
846 /* don't trust the remote processor for null terminating the name */
847 msg->name[RPMSG_NAME_SIZE - 1] = '\0';
848
849 dev_info(dev, "%sing channel %s addr 0x%x\n",
850 msg->flags & RPMSG_NS_DESTROY ? "destroy" : "creat",
851 msg->name, msg->addr);
852
853 strncpy(chinfo.name, msg->name, sizeof(chinfo.name));
854 chinfo.src = RPMSG_ADDR_ANY;
855 chinfo.dst = msg->addr;
856
857 if (msg->flags & RPMSG_NS_DESTROY) {
858 ret = rpmsg_unregister_device(&vrp->vdev->dev, &chinfo);
859 if (ret)
860 dev_err(dev, "rpmsg_destroy_channel failed: %d\n", ret);
861 } else {
862 newch = rpmsg_create_channel(vrp, &chinfo);
863 if (!newch)
864 dev_err(dev, "rpmsg_create_channel failed\n");
865 }
866
867 return 0;
868}
869
870static int rpmsg_probe(struct virtio_device *vdev)
871{
872 vq_callback_t *vq_cbs[] = { rpmsg_recv_done, rpmsg_xmit_done };
873 static const char * const names[] = { "input", "output" };
874 struct virtqueue *vqs[2];
875 struct virtproc_info *vrp;
876 void *bufs_va;
877 int err = 0, i;
878 size_t total_buf_space;
879 bool notify;
880
881 vrp = kzalloc(sizeof(*vrp), GFP_KERNEL);
882 if (!vrp)
883 return -ENOMEM;
884
885 vrp->vdev = vdev;
886
887 idr_init(&vrp->endpoints);
888 mutex_init(&vrp->endpoints_lock);
889 mutex_init(&vrp->tx_lock);
890 init_waitqueue_head(&vrp->sendq);
891
892 /* We expect two virtqueues, rx and tx (and in this order) */
893 err = virtio_find_vqs(vdev, 2, vqs, vq_cbs, names, NULL);
894 if (err)
895 goto free_vrp;
896
897 vrp->rvq = vqs[0];
898 vrp->svq = vqs[1];
899
900 /* we expect symmetric tx/rx vrings */
901 WARN_ON(virtqueue_get_vring_size(vrp->rvq) !=
902 virtqueue_get_vring_size(vrp->svq));
903
904 /* we need less buffers if vrings are small */
905 if (virtqueue_get_vring_size(vrp->rvq) < MAX_RPMSG_NUM_BUFS / 2)
906 vrp->num_bufs = virtqueue_get_vring_size(vrp->rvq) * 2;
907 else
908 vrp->num_bufs = MAX_RPMSG_NUM_BUFS;
909
910 vrp->buf_size = MAX_RPMSG_BUF_SIZE;
911
912 total_buf_space = vrp->num_bufs * vrp->buf_size;
913
914 /* allocate coherent memory for the buffers */
915 bufs_va = dma_alloc_coherent(vdev->dev.parent,
916 total_buf_space, &vrp->bufs_dma,
917 GFP_KERNEL);
918 if (!bufs_va) {
919 err = -ENOMEM;
920 goto vqs_del;
921 }
922
923 dev_dbg(&vdev->dev, "buffers: va %p, dma %pad\n",
924 bufs_va, &vrp->bufs_dma);
925
926 /* half of the buffers is dedicated for RX */
927 vrp->rbufs = bufs_va;
928
929 /* and half is dedicated for TX */
930 vrp->sbufs = bufs_va + total_buf_space / 2;
931
932 /* set up the receive buffers */
933 for (i = 0; i < vrp->num_bufs / 2; i++) {
934 struct scatterlist sg;
935 void *cpu_addr = vrp->rbufs + i * vrp->buf_size;
936
937 rpmsg_sg_init(&sg, cpu_addr, vrp->buf_size);
938
939 err = virtqueue_add_inbuf(vrp->rvq, &sg, 1, cpu_addr,
940 GFP_KERNEL);
941 WARN_ON(err); /* sanity check; this can't really happen */
942 }
943
944 /* suppress "tx-complete" interrupts */
945 virtqueue_disable_cb(vrp->svq);
946
947 vdev->priv = vrp;
948
949 /* if supported by the remote processor, enable the name service */
950 if (virtio_has_feature(vdev, VIRTIO_RPMSG_F_NS)) {
951 /* a dedicated endpoint handles the name service msgs */
952 vrp->ns_ept = __rpmsg_create_ept(vrp, NULL, rpmsg_ns_cb,
953 vrp, RPMSG_NS_ADDR);
954 if (!vrp->ns_ept) {
955 dev_err(&vdev->dev, "failed to create the ns ept\n");
956 err = -ENOMEM;
957 goto free_coherent;
958 }
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_coherent:
983 dma_free_coherent(vdev->dev.parent, total_buf_space,
984 bufs_va, vrp->bufs_dma);
985vqs_del:
986 vdev->config->del_vqs(vrp->vdev);
987free_vrp:
988 kfree(vrp);
989 return err;
990}
991
992static int rpmsg_remove_device(struct device *dev, void *data)
993{
994 device_unregister(dev);
995
996 return 0;
997}
998
999static void rpmsg_remove(struct virtio_device *vdev)
1000{
1001 struct virtproc_info *vrp = vdev->priv;
1002 size_t total_buf_space = vrp->num_bufs * vrp->buf_size;
1003 int ret;
1004
1005 vdev->config->reset(vdev);
1006
1007 ret = device_for_each_child(&vdev->dev, NULL, rpmsg_remove_device);
1008 if (ret)
1009 dev_warn(&vdev->dev, "can't remove rpmsg device: %d\n", ret);
1010
1011 if (vrp->ns_ept)
1012 __rpmsg_destroy_ept(vrp, vrp->ns_ept);
1013
1014 idr_destroy(&vrp->endpoints);
1015
1016 vdev->config->del_vqs(vrp->vdev);
1017
1018 dma_free_coherent(vdev->dev.parent, total_buf_space,
1019 vrp->rbufs, vrp->bufs_dma);
1020
1021 kfree(vrp);
1022}
1023
1024static struct virtio_device_id id_table[] = {
1025 { VIRTIO_ID_RPMSG, VIRTIO_DEV_ANY_ID },
1026 { 0 },
1027};
1028
1029static unsigned int features[] = {
1030 VIRTIO_RPMSG_F_NS,
1031};
1032
1033static struct virtio_driver virtio_ipc_driver = {
1034 .feature_table = features,
1035 .feature_table_size = ARRAY_SIZE(features),
1036 .driver.name = KBUILD_MODNAME,
1037 .driver.owner = THIS_MODULE,
1038 .id_table = id_table,
1039 .probe = rpmsg_probe,
1040 .remove = rpmsg_remove,
1041};
1042
1043static int __init rpmsg_init(void)
1044{
1045 int ret;
1046
1047 ret = register_virtio_driver(&virtio_ipc_driver);
1048 if (ret)
1049 pr_err("failed to register virtio driver: %d\n", ret);
1050
1051 return ret;
1052}
1053subsys_initcall(rpmsg_init);
1054
1055static void __exit rpmsg_fini(void)
1056{
1057 unregister_virtio_driver(&virtio_ipc_driver);
1058}
1059module_exit(rpmsg_fini);
1060
1061MODULE_DEVICE_TABLE(virtio, id_table);
1062MODULE_DESCRIPTION("Virtio-based remote processor messaging bus");
1063MODULE_LICENSE("GPL v2");
1064