1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * 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/kernel.h>
15 #include <linux/module.h>
16 #include <linux/rpmsg.h>
17 #include <linux/of_device.h>
18 #include <linux/pm_domain.h>
19 #include <linux/slab.h>
20
21 #include "rpmsg_internal.h"
22
23 /**
24 * rpmsg_create_ept() - create a new rpmsg_endpoint
25 * @rpdev: rpmsg channel device
26 * @cb: rx callback handler
27 * @priv: private data for the driver's use
28 * @chinfo: channel_info with the local rpmsg address to bind with @cb
29 *
30 * Every rpmsg address in the system is bound to an rx callback (so when
31 * inbound messages arrive, they are dispatched by the rpmsg bus using the
32 * appropriate callback handler) by means of an rpmsg_endpoint struct.
33 *
34 * This function allows drivers to create such an endpoint, and by that,
35 * bind a callback, and possibly some private data too, to an rpmsg address
36 * (either one that is known in advance, or one that will be dynamically
37 * assigned for them).
38 *
39 * Simple rpmsg drivers need not call rpmsg_create_ept, because an endpoint
40 * is already created for them when they are probed by the rpmsg bus
41 * (using the rx callback provided when they registered to the rpmsg bus).
42 *
43 * So things should just work for simple drivers: they already have an
44 * endpoint, their rx callback is bound to their rpmsg address, and when
45 * relevant inbound messages arrive (i.e. messages which their dst address
46 * equals to the src address of their rpmsg channel), the driver's handler
47 * is invoked to process it.
48 *
49 * That said, more complicated drivers might need to allocate
50 * additional rpmsg addresses, and bind them to different rx callbacks.
51 * To accomplish that, those drivers need to call this function.
52 *
53 * Drivers should provide their @rpdev channel (so the new endpoint would belong
54 * to the same remote processor their channel belongs to), an rx callback
55 * function, an optional private data (which is provided back when the
56 * rx callback is invoked), and an address they want to bind with the
57 * callback. If @addr is RPMSG_ADDR_ANY, then rpmsg_create_ept will
58 * dynamically assign them an available rpmsg address (drivers should have
59 * a very good reason why not to always use RPMSG_ADDR_ANY here).
60 *
61 * Returns a pointer to the endpoint on success, or NULL on error.
62 */
63 struct rpmsg_endpoint *rpmsg_create_ept(struct rpmsg_device *rpdev,
64 rpmsg_rx_cb_t cb, void *priv,
65 struct rpmsg_channel_info chinfo)
66 {
67 if (WARN_ON(!rpdev))
68 return NULL;
69
70 return rpdev->ops->create_ept(rpdev, cb, priv, chinfo);
71 }
72 EXPORT_SYMBOL(rpmsg_create_ept);
73
74 /**
75 * rpmsg_destroy_ept() - destroy an existing rpmsg endpoint
76 * @ept: endpoing to destroy
77 *
78 * Should be used by drivers to destroy an rpmsg endpoint previously
79 * created with rpmsg_create_ept(). As with other types of "free" NULL
80 * is a valid parameter.
81 */
82 void rpmsg_destroy_ept(struct rpmsg_endpoint *ept)
83 {
84 if (ept)
85 ept->ops->destroy_ept(ept);
86 }
87 EXPORT_SYMBOL(rpmsg_destroy_ept);
88
89 /**
90 * rpmsg_send() - send a message across to the remote processor
91 * @ept: the rpmsg endpoint
92 * @data: payload of message
93 * @len: length of payload
94 *
95 * This function sends @data of length @len on the @ept endpoint.
96 * The message will be sent to the remote processor which the @ept
97 * endpoint belongs to, using @ept's address and its associated rpmsg
98 * device destination addresses.
99 * In case there are no TX buffers available, the function will block until
100 * one becomes available, or a timeout of 15 seconds elapses. When the latter
101 * happens, -ERESTARTSYS is returned.
102 *
103 * Can only be called from process context (for now).
104 *
105 * Returns 0 on success and an appropriate error value on failure.
106 */
107 int rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len)
108 {
109 if (WARN_ON(!ept))
110 return -EINVAL;
111 if (!ept->ops->send)
112 return -ENXIO;
113
114 return ept->ops->send(ept, data, len);
115 }
116 EXPORT_SYMBOL(rpmsg_send);
117
118 /**
119 * rpmsg_sendto() - send a message across to the remote processor, specify dst
120 * @ept: the rpmsg endpoint
121 * @data: payload of message
122 * @len: length of payload
123 * @dst: destination address
124 *
125 * This function sends @data of length @len to the remote @dst address.
126 * The message will be sent to the remote processor which the @ept
127 * endpoint belongs to, using @ept's address as source.
128 * In case there are no TX buffers available, the function will block until
129 * one becomes available, or a timeout of 15 seconds elapses. When the latter
130 * happens, -ERESTARTSYS is returned.
131 *
132 * Can only be called from process context (for now).
133 *
134 * Returns 0 on success and an appropriate error value on failure.
135 */
136 int rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len, u32 dst)
137 {
138 if (WARN_ON(!ept))
139 return -EINVAL;
140 if (!ept->ops->sendto)
141 return -ENXIO;
142
143 return ept->ops->sendto(ept, data, len, dst);
144 }
145 EXPORT_SYMBOL(rpmsg_sendto);
146
147 /**
148 * rpmsg_send_offchannel() - send a message using explicit src/dst addresses
149 * @ept: the rpmsg endpoint
150 * @src: source address
151 * @dst: destination address
152 * @data: payload of message
153 * @len: length of payload
154 *
155 * This function sends @data of length @len to the remote @dst address,
156 * and uses @src as the source address.
157 * The message will be sent to the remote processor which the @ept
158 * endpoint belongs to.
159 * In case there are no TX buffers available, the function will block until
160 * one becomes available, or a timeout of 15 seconds elapses. When the latter
161 * happens, -ERESTARTSYS is returned.
162 *
163 * Can only be called from process context (for now).
164 *
165 * Returns 0 on success and an appropriate error value on failure.
166 */
167 int rpmsg_send_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
168 void *data, int len)
169 {
170 if (WARN_ON(!ept))
171 return -EINVAL;
172 if (!ept->ops->send_offchannel)
173 return -ENXIO;
174
175 return ept->ops->send_offchannel(ept, src, dst, data, len);
176 }
177 EXPORT_SYMBOL(rpmsg_send_offchannel);
178
179 /**
180 * rpmsg_trysend() - send a message across to the remote processor
181 * @ept: the rpmsg endpoint
182 * @data: payload of message
183 * @len: length of payload
184 *
185 * This function sends @data of length @len on the @ept endpoint.
186 * The message will be sent to the remote processor which the @ept
187 * endpoint belongs to, using @ept's address as source and its associated
188 * rpdev's address as destination.
189 * In case there are no TX buffers available, the function will immediately
190 * return -ENOMEM without waiting until one becomes available.
191 *
192 * Can only be called from process context (for now).
193 *
194 * Returns 0 on success and an appropriate error value on failure.
195 */
196 int rpmsg_trysend(struct rpmsg_endpoint *ept, void *data, int len)
197 {
198 if (WARN_ON(!ept))
199 return -EINVAL;
200 if (!ept->ops->trysend)
201 return -ENXIO;
202
203 return ept->ops->trysend(ept, data, len);
204 }
205 EXPORT_SYMBOL(rpmsg_trysend);
206
207 /**
208 * rpmsg_trysendto() - send a message across to the remote processor, specify dst
209 * @ept: the rpmsg endpoint
210 * @data: payload of message
211 * @len: length of payload
212 * @dst: destination address
213 *
214 * This function sends @data of length @len to the remote @dst address.
215 * The message will be sent to the remote processor which the @ept
216 * endpoint belongs to, using @ept's address as source.
217 * In case there are no TX buffers available, the function will immediately
218 * return -ENOMEM without waiting until one becomes available.
219 *
220 * Can only be called from process context (for now).
221 *
222 * Returns 0 on success and an appropriate error value on failure.
223 */
224 int rpmsg_trysendto(struct rpmsg_endpoint *ept, void *data, int len, u32 dst)
225 {
226 if (WARN_ON(!ept))
227 return -EINVAL;
228 if (!ept->ops->trysendto)
229 return -ENXIO;
230
231 return ept->ops->trysendto(ept, data, len, dst);
232 }
233 EXPORT_SYMBOL(rpmsg_trysendto);
234
235 /**
236 * rpmsg_poll() - poll the endpoint's send buffers
237 * @ept: the rpmsg endpoint
238 * @filp: file for poll_wait()
239 * @wait: poll_table for poll_wait()
240 *
241 * Returns mask representing the current state of the endpoint's send buffers
242 */
243 __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
244 poll_table *wait)
245 {
246 if (WARN_ON(!ept))
247 return 0;
248 if (!ept->ops->poll)
249 return 0;
250
251 return ept->ops->poll(ept, filp, wait);
252 }
253 EXPORT_SYMBOL(rpmsg_poll);
254
255 /**
256 * rpmsg_trysend_offchannel() - send a message using explicit src/dst addresses
257 * @ept: the rpmsg endpoint
258 * @src: source address
259 * @dst: destination address
260 * @data: payload of message
261 * @len: length of payload
262 *
263 * This function sends @data of length @len to the remote @dst address,
264 * and uses @src as the source address.
265 * The message will be sent to the remote processor which the @ept
266 * endpoint belongs to.
267 * In case there are no TX buffers available, the function will immediately
268 * return -ENOMEM without waiting until one becomes available.
269 *
270 * Can only be called from process context (for now).
271 *
272 * Returns 0 on success and an appropriate error value on failure.
273 */
274 int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
275 void *data, int len)
276 {
277 if (WARN_ON(!ept))
278 return -EINVAL;
279 if (!ept->ops->trysend_offchannel)
280 return -ENXIO;
281
282 return ept->ops->trysend_offchannel(ept, src, dst, data, len);
283 }
284 EXPORT_SYMBOL(rpmsg_trysend_offchannel);
285
286 /*
287 * match an rpmsg channel with a channel info struct.
288 * this is used to make sure we're not creating rpmsg devices for channels
289 * that already exist.
290 */
291 static int rpmsg_device_match(struct device *dev, void *data)
292 {
293 struct rpmsg_channel_info *chinfo = data;
294 struct rpmsg_device *rpdev = to_rpmsg_device(dev);
295
296 if (chinfo->src != RPMSG_ADDR_ANY && chinfo->src != rpdev->src)
297 return 0;
298
299 if (chinfo->dst != RPMSG_ADDR_ANY && chinfo->dst != rpdev->dst)
300 return 0;
301
302 if (strncmp(chinfo->name, rpdev->id.name, RPMSG_NAME_SIZE))
303 return 0;
304
305 /* found a match ! */
306 return 1;
307 }
308
309 struct device *rpmsg_find_device(struct device *parent,
310 struct rpmsg_channel_info *chinfo)
311 {
312 return device_find_child(parent, chinfo, rpmsg_device_match);
313
314 }
315 EXPORT_SYMBOL(rpmsg_find_device);
316
317 /* sysfs show configuration fields */
318 #define rpmsg_show_attr(field, path, format_string) \
319 static ssize_t \
320 field##_show(struct device *dev, \
321 struct device_attribute *attr, char *buf) \
322 { \
323 struct rpmsg_device *rpdev = to_rpmsg_device(dev); \
324 \
325 return sprintf(buf, format_string, rpdev->path); \
326 } \
327 static DEVICE_ATTR_RO(field);
328
329 #define rpmsg_string_attr(field, member) \
330 static ssize_t \
331 field##_store(struct device *dev, struct device_attribute *attr, \
332 const char *buf, size_t sz) \
333 { \
334 struct rpmsg_device *rpdev = to_rpmsg_device(dev); \
335 char *new, *old; \
336 \
337 new = kstrndup(buf, sz, GFP_KERNEL); \
338 if (!new) \
339 return -ENOMEM; \
340 new[strcspn(new, "\n")] = '\0'; \
341 \
342 device_lock(dev); \
343 old = rpdev->member; \
344 if (strlen(new)) { \
345 rpdev->member = new; \
346 } else { \
347 kfree(new); \
348 rpdev->member = NULL; \
349 } \
350 device_unlock(dev); \
351 \
352 kfree(old); \
353 \
354 return sz; \
355 } \
356 static ssize_t \
357 field##_show(struct device *dev, \
358 struct device_attribute *attr, char *buf) \
359 { \
360 struct rpmsg_device *rpdev = to_rpmsg_device(dev); \
361 \
362 return sprintf(buf, "%s\n", rpdev->member); \
363 } \
364 static DEVICE_ATTR_RW(field)
365
366 /* for more info, see Documentation/ABI/testing/sysfs-bus-rpmsg */
367 rpmsg_show_attr(name, id.name, "%s\n");
368 rpmsg_show_attr(src, src, "0x%x\n");
369 rpmsg_show_attr(dst, dst, "0x%x\n");
370 rpmsg_show_attr(announce, announce ? "true" : "false", "%s\n");
371 rpmsg_string_attr(driver_override, driver_override);
372
373 static ssize_t modalias_show(struct device *dev,
374 struct device_attribute *attr, char *buf)
375 {
376 struct rpmsg_device *rpdev = to_rpmsg_device(dev);
377 ssize_t len;
378
379 len = of_device_modalias(dev, buf, PAGE_SIZE);
380 if (len != -ENODEV)
381 return len;
382
383 return sprintf(buf, RPMSG_DEVICE_MODALIAS_FMT "\n", rpdev->id.name);
384 }
385 static DEVICE_ATTR_RO(modalias);
386
387 static struct attribute *rpmsg_dev_attrs[] = {
388 &dev_attr_name.attr,
389 &dev_attr_modalias.attr,
390 &dev_attr_dst.attr,
391 &dev_attr_src.attr,
392 &dev_attr_announce.attr,
393 &dev_attr_driver_override.attr,
394 NULL,
395 };
396 ATTRIBUTE_GROUPS(rpmsg_dev);
397
398 /* rpmsg devices and drivers are matched using the service name */
399 static inline int rpmsg_id_match(const struct rpmsg_device *rpdev,
400 const struct rpmsg_device_id *id)
401 {
402 return strncmp(id->name, rpdev->id.name, RPMSG_NAME_SIZE) == 0;
403 }
404
405 /* match rpmsg channel and rpmsg driver */
406 static int rpmsg_dev_match(struct device *dev, struct device_driver *drv)
407 {
408 struct rpmsg_device *rpdev = to_rpmsg_device(dev);
409 struct rpmsg_driver *rpdrv = to_rpmsg_driver(drv);
410 const struct rpmsg_device_id *ids = rpdrv->id_table;
411 unsigned int i;
412
413 if (rpdev->driver_override)
414 return !strcmp(rpdev->driver_override, drv->name);
415
416 if (ids)
417 for (i = 0; ids[i].name[0]; i++)
418 if (rpmsg_id_match(rpdev, &ids[i]))
419 return 1;
420
421 return of_driver_match_device(dev, drv);
422 }
423
424 static int rpmsg_uevent(struct device *dev, struct kobj_uevent_env *env)
425 {
426 struct rpmsg_device *rpdev = to_rpmsg_device(dev);
427 int ret;
428
429 ret = of_device_uevent_modalias(dev, env);
430 if (ret != -ENODEV)
431 return ret;
432
433 return add_uevent_var(env, "MODALIAS=" RPMSG_DEVICE_MODALIAS_FMT,
434 rpdev->id.name);
435 }
436
437 /*
438 * when an rpmsg driver is probed with a channel, we seamlessly create
439 * it an endpoint, binding its rx callback to a unique local rpmsg
440 * address.
441 *
442 * if we need to, we also announce about this channel to the remote
443 * processor (needed in case the driver is exposing an rpmsg service).
444 */
445 static int rpmsg_dev_probe(struct device *dev)
446 {
447 struct rpmsg_device *rpdev = to_rpmsg_device(dev);
448 struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
449 struct rpmsg_channel_info chinfo = {};
450 struct rpmsg_endpoint *ept = NULL;
451 int err;
452
453 err = dev_pm_domain_attach(dev, true);
454 if (err)
455 goto out;
456
457 if (rpdrv->callback) {
458 strncpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE);
459 chinfo.src = rpdev->src;
460 chinfo.dst = RPMSG_ADDR_ANY;
461
462 ept = rpmsg_create_ept(rpdev, rpdrv->callback, NULL, chinfo);
463 if (!ept) {
464 dev_err(dev, "failed to create endpoint\n");
465 err = -ENOMEM;
466 goto out;
467 }
468
469 rpdev->ept = ept;
470 rpdev->src = ept->addr;
471 }
472
473 err = rpdrv->probe(rpdev);
474 if (err) {
475 dev_err(dev, "%s: failed: %d\n", __func__, err);
476 if (ept)
477 rpmsg_destroy_ept(ept);
478 goto out;
479 }
480
481 if (ept && rpdev->ops->announce_create)
482 err = rpdev->ops->announce_create(rpdev);
483 out:
484 return err;
485 }
486
487 static int rpmsg_dev_remove(struct device *dev)
488 {
489 struct rpmsg_device *rpdev = to_rpmsg_device(dev);
490 struct rpmsg_driver *rpdrv = to_rpmsg_driver(rpdev->dev.driver);
491 int err = 0;
492
493 if (rpdev->ops->announce_destroy)
494 err = rpdev->ops->announce_destroy(rpdev);
495
496 if (rpdrv->remove)
497 rpdrv->remove(rpdev);
498
499 dev_pm_domain_detach(dev, true);
500
501 if (rpdev->ept)
502 rpmsg_destroy_ept(rpdev->ept);
503
504 return err;
505 }
506
507 static struct bus_type rpmsg_bus = {
508 .name = "rpmsg",
509 .match = rpmsg_dev_match,
510 .dev_groups = rpmsg_dev_groups,
511 .uevent = rpmsg_uevent,
512 .probe = rpmsg_dev_probe,
513 .remove = rpmsg_dev_remove,
514 };
515
516 int rpmsg_register_device(struct rpmsg_device *rpdev)
517 {
518 struct device *dev = &rpdev->dev;
519 int ret;
520
521 dev_set_name(&rpdev->dev, "%s.%s.%d.%d", dev_name(dev->parent),
522 rpdev->id.name, rpdev->src, rpdev->dst);
523
524 rpdev->dev.bus = &rpmsg_bus;
525
526 ret = device_register(&rpdev->dev);
527 if (ret) {
528 dev_err(dev, "device_register failed: %d\n", ret);
529 put_device(&rpdev->dev);
530 }
531
532 return ret;
533 }
534 EXPORT_SYMBOL(rpmsg_register_device);
535
536 /*
537 * find an existing channel using its name + address properties,
538 * and destroy it
539 */
540 int rpmsg_unregister_device(struct device *parent,
541 struct rpmsg_channel_info *chinfo)
542 {
543 struct device *dev;
544
545 dev = rpmsg_find_device(parent, chinfo);
546 if (!dev)
547 return -EINVAL;
548
549 device_unregister(dev);
550
551 put_device(dev);
552
553 return 0;
554 }
555 EXPORT_SYMBOL(rpmsg_unregister_device);
556
557 /**
558 * __register_rpmsg_driver() - register an rpmsg driver with the rpmsg bus
559 * @rpdrv: pointer to a struct rpmsg_driver
560 * @owner: owning module/driver
561 *
562 * Returns 0 on success, and an appropriate error value on failure.
563 */
564 int __register_rpmsg_driver(struct rpmsg_driver *rpdrv, struct module *owner)
565 {
566 rpdrv->drv.bus = &rpmsg_bus;
567 rpdrv->drv.owner = owner;
568 return driver_register(&rpdrv->drv);
569 }
570 EXPORT_SYMBOL(__register_rpmsg_driver);
571
572 /**
573 * unregister_rpmsg_driver() - unregister an rpmsg driver from the rpmsg bus
574 * @rpdrv: pointer to a struct rpmsg_driver
575 *
576 * Returns 0 on success, and an appropriate error value on failure.
577 */
578 void unregister_rpmsg_driver(struct rpmsg_driver *rpdrv)
579 {
580 driver_unregister(&rpdrv->drv);
581 }
582 EXPORT_SYMBOL(unregister_rpmsg_driver);
583
584
585 static int __init rpmsg_init(void)
586 {
587 int ret;
588
589 ret = bus_register(&rpmsg_bus);
590 if (ret)
591 pr_err("failed to register rpmsg bus: %d\n", ret);
592
593 return ret;
594 }
595 postcore_initcall(rpmsg_init);
596
597 static void __exit rpmsg_fini(void)
598 {
599 bus_unregister(&rpmsg_bus);
600 }
601 module_exit(rpmsg_fini);
602
603 MODULE_DESCRIPTION("remote processor messaging bus");
604 MODULE_LICENSE("GPL v2");