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