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(x: cpu_addr)) {
173 sg_init_table(sg, 1);
174 sg_set_page(sg, page: vmalloc_to_page(addr: 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(objp: 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(kref: &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, ptr: ept, start: id_min, end: 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(lock: &vrp->endpoints_lock);
244
245 return ept;
246
247free_ept:
248 mutex_unlock(lock: &vrp->endpoints_lock);
249 kref_put(kref: &ept->refcount, release: __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(parent: &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(vrp: vch->vrp, rpdev, cb, priv, addr: 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, id: ept->addr);
297 mutex_unlock(lock: &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(lock: &ept->cb_lock);
303
304 kref_put(kref: &ept->refcount, release: __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(vrp: 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(vdev: 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, val: rpdev->ept->addr);
328 nsm.flags = cpu_to_rpmsg32(rpdev, val: RPMSG_NS_CREATE);
329
330 err = rpmsg_sendto(ept: rpdev->ept, data: &nsm, len: 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(vdev: 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, val: rpdev->ept->addr);
352 nsm.flags = cpu_to_rpmsg32(rpdev, val: RPMSG_NS_DESTROY);
353
354 err = rpmsg_sendto(ept: rpdev->ept, data: &nsm, len: 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(objp: rpdev->driver_override);
376 kfree(objp: 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(parent: dev, chinfo);
394 if (tmp) {
395 /* decrement the matched device's refcount back */
396 put_device(dev: 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(vdev: 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(vq: vrp->svq, len: &len);
451
452 mutex_unlock(lock: &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(v: &vrp->sleepers) == 1)
480 /* enable "tx-complete" interrupts before dozing off */
481 virtqueue_enable_cb(vq: vrp->svq);
482
483 mutex_unlock(lock: &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(v: &vrp->sleepers))
507 /* disable "tx-complete" interrupts */
508 virtqueue_disable_cb(vq: vrp->svq);
509
510 mutex_unlock(lock: &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, val: len);
609 msg->flags = 0;
610 msg->src = cpu_to_rpmsg32(rpdev, val: src);
611 msg->dst = cpu_to_rpmsg32(rpdev, val: 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: &sg, cpu_addr: msg, len: 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(vq: vrp->svq, sg: &sg, num: 1, data: 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(vq: vrp->svq);
640out:
641 mutex_unlock(lock: &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, wait: 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, wait: 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, wait: 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, wait: 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(vdev: vrp->vdev);
693 unsigned int msg_len = __rpmsg16_to_cpu(little_endian, val: 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, id: __rpmsg32_to_cpu(little_endian, val: msg->dst));
720
721 /* let's make sure no one deallocates ept while we use it */
722 if (ept)
723 kref_get(kref: &ept->refcount);
724
725 mutex_unlock(lock: &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, val: msg->src));
734
735 mutex_unlock(lock: &ept->cb_lock);
736
737 /* farewell, ept, we don't need you anymore */
738 kref_put(kref: &ept->refcount, release: __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: &sg, cpu_addr: msg, len: vrp->buf_size);
744
745 /* add the buffer back to the remote processor's virtqueue */
746 err = virtqueue_add_inbuf(vq: vrp->rvq, sg: &sg, num: 1, data: 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(vq: rvq, len: &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(vq: rvq, len: &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(vq: 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(error: -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(vdev: vrp->vdev);
830
831 err = rpmsg_ctrldev_register_device(rpdev: rpdev_ctrl);
832 if (err) {
833 /* vch will be free in virtio_rpmsg_release_device() */
834 return ERR_PTR(error: 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(dev: &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(idr: &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, nvqs: 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(vq: vrp->rvq) < MAX_RPMSG_NUM_BUFS / 2)
887 vrp->num_bufs = virtqueue_get_vring_size(vq: 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(dev: vdev->dev.parent,
897 size: total_buf_space, dma_handle: &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: &sg, cpu_addr, len: vrp->buf_size);
919
920 err = virtqueue_add_inbuf(vq: vrp->rvq, sg: &sg, num: 1, data: 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(vq: vrp->svq);
927
928 vdev->priv = vrp;
929
930 rpdev_ctrl = rpmsg_virtio_add_ctrl_dev(vdev);
931 if (IS_ERR(ptr: rpdev_ctrl)) {
932 err = PTR_ERR(ptr: 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(vdev: 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: 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(vq: vrp->rvq);
966
967 /* From this point on, we can notify and get callbacks. */
968 virtio_device_ready(dev: 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(vq: 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(dev: vdev->dev.parent, size: total_buf_space,
986 cpu_addr: bufs_va, dma_handle: vrp->bufs_dma);
987vqs_del:
988 vdev->config->del_vqs(vrp->vdev);
989free_vrp:
990 kfree(objp: 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(dev: vdev);
1008
1009 ret = device_for_each_child(parent: &vdev->dev, NULL, fn: 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(dev: vdev->dev.parent, size: total_buf_space,
1018 cpu_addr: vrp->rbufs, dma_handle: vrp->bufs_dma);
1019
1020 kfree(objp: 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(drv: &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");
1062

source code of linux/drivers/rpmsg/virtio_rpmsg_bus.c