1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * System Control and Management Interface (SCMI) Message Protocol bus layer
4 *
5 * Copyright (C) 2018-2021 ARM Ltd.
6 */
7
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10 #include <linux/atomic.h>
11 #include <linux/types.h>
12 #include <linux/module.h>
13 #include <linux/of.h>
14 #include <linux/kernel.h>
15 #include <linux/slab.h>
16 #include <linux/device.h>
17
18 #include "common.h"
19
20 #define SCMI_UEVENT_MODALIAS_FMT "%s:%02x:%s"
21
22 BLOCKING_NOTIFIER_HEAD(scmi_requested_devices_nh);
23 EXPORT_SYMBOL_GPL(scmi_requested_devices_nh);
24
25 static DEFINE_IDA(scmi_bus_id);
26
27 static DEFINE_IDR(scmi_requested_devices);
28 /* Protect access to scmi_requested_devices */
29 static DEFINE_MUTEX(scmi_requested_devices_mtx);
30
31 struct scmi_requested_dev {
32 const struct scmi_device_id *id_table;
33 struct list_head node;
34 };
35
36 /* Track globally the creation of SCMI SystemPower related devices */
37 static atomic_t scmi_syspower_registered = ATOMIC_INIT(0);
38
39 /**
40 * scmi_protocol_device_request - Helper to request a device
41 *
42 * @id_table: A protocol/name pair descriptor for the device to be created.
43 *
44 * This helper let an SCMI driver request specific devices identified by the
45 * @id_table to be created for each active SCMI instance.
46 *
47 * The requested device name MUST NOT be already existent for this protocol;
48 * at first the freshly requested @id_table is annotated in the IDR table
49 * @scmi_requested_devices and then the requested device is advertised to any
50 * registered party via the @scmi_requested_devices_nh notification chain.
51 *
52 * Return: 0 on Success
53 */
scmi_protocol_device_request(const struct scmi_device_id * id_table)54 static int scmi_protocol_device_request(const struct scmi_device_id *id_table)
55 {
56 int ret = 0;
57 struct list_head *head, *phead = NULL;
58 struct scmi_requested_dev *rdev;
59
60 pr_debug("Requesting SCMI device (%s) for protocol %x\n",
61 id_table->name, id_table->protocol_id);
62
63 if (IS_ENABLED(CONFIG_ARM_SCMI_RAW_MODE_SUPPORT) &&
64 !IS_ENABLED(CONFIG_ARM_SCMI_RAW_MODE_SUPPORT_COEX)) {
65 pr_warn("SCMI Raw mode active. Rejecting '%s'/0x%02X\n",
66 id_table->name, id_table->protocol_id);
67 return -EINVAL;
68 }
69
70 /*
71 * Find the matching protocol rdev list and then search of any
72 * existent equally named device...fails if any duplicate found.
73 */
74 mutex_lock(&scmi_requested_devices_mtx);
75 phead = idr_find(&scmi_requested_devices, id_table->protocol_id);
76 if (phead) {
77 head = phead;
78 list_for_each_entry(rdev, head, node) {
79 if (!strcmp(rdev->id_table->name, id_table->name)) {
80 pr_err("Ignoring duplicate request [%d] %s\n",
81 rdev->id_table->protocol_id,
82 rdev->id_table->name);
83 ret = -EINVAL;
84 goto out;
85 }
86 }
87 }
88
89 /*
90 * No duplicate found for requested id_table, so let's create a new
91 * requested device entry for this new valid request.
92 */
93 rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
94 if (!rdev) {
95 ret = -ENOMEM;
96 goto out;
97 }
98 rdev->id_table = id_table;
99
100 /*
101 * Append the new requested device table descriptor to the head of the
102 * related protocol list, eventually creating such head if not already
103 * there.
104 */
105 if (!phead) {
106 phead = kzalloc(sizeof(*phead), GFP_KERNEL);
107 if (!phead) {
108 kfree(rdev);
109 ret = -ENOMEM;
110 goto out;
111 }
112 INIT_LIST_HEAD(phead);
113
114 ret = idr_alloc(&scmi_requested_devices, (void *)phead,
115 id_table->protocol_id,
116 id_table->protocol_id + 1, GFP_KERNEL);
117 if (ret != id_table->protocol_id) {
118 pr_err("Failed to save SCMI device - ret:%d\n", ret);
119 kfree(rdev);
120 kfree(phead);
121 ret = -EINVAL;
122 goto out;
123 }
124 ret = 0;
125 }
126 list_add(&rdev->node, phead);
127
128 out:
129 mutex_unlock(&scmi_requested_devices_mtx);
130
131 if (!ret)
132 blocking_notifier_call_chain(&scmi_requested_devices_nh,
133 SCMI_BUS_NOTIFY_DEVICE_REQUEST,
134 (void *)rdev->id_table);
135
136 return ret;
137 }
138
scmi_protocol_table_register(const struct scmi_device_id * id_table)139 static int scmi_protocol_table_register(const struct scmi_device_id *id_table)
140 {
141 int ret = 0;
142 const struct scmi_device_id *entry;
143
144 for (entry = id_table; entry->name && ret == 0; entry++)
145 ret = scmi_protocol_device_request(entry);
146
147 return ret;
148 }
149
150 /**
151 * scmi_protocol_device_unrequest - Helper to unrequest a device
152 *
153 * @id_table: A protocol/name pair descriptor for the device to be unrequested.
154 *
155 * The unrequested device, described by the provided id_table, is at first
156 * removed from the IDR @scmi_requested_devices and then the removal is
157 * advertised to any registered party via the @scmi_requested_devices_nh
158 * notification chain.
159 */
scmi_protocol_device_unrequest(const struct scmi_device_id * id_table)160 static void scmi_protocol_device_unrequest(const struct scmi_device_id *id_table)
161 {
162 struct list_head *phead;
163
164 pr_debug("Unrequesting SCMI device (%s) for protocol %x\n",
165 id_table->name, id_table->protocol_id);
166
167 mutex_lock(&scmi_requested_devices_mtx);
168 phead = idr_find(&scmi_requested_devices, id_table->protocol_id);
169 if (phead) {
170 struct scmi_requested_dev *victim, *tmp;
171
172 list_for_each_entry_safe(victim, tmp, phead, node) {
173 if (!strcmp(victim->id_table->name, id_table->name)) {
174 list_del(&victim->node);
175
176 mutex_unlock(&scmi_requested_devices_mtx);
177 blocking_notifier_call_chain(&scmi_requested_devices_nh,
178 SCMI_BUS_NOTIFY_DEVICE_UNREQUEST,
179 (void *)victim->id_table);
180 kfree(victim);
181 mutex_lock(&scmi_requested_devices_mtx);
182 break;
183 }
184 }
185
186 if (list_empty(phead)) {
187 idr_remove(&scmi_requested_devices,
188 id_table->protocol_id);
189 kfree(phead);
190 }
191 }
192 mutex_unlock(&scmi_requested_devices_mtx);
193 }
194
195 static void
scmi_protocol_table_unregister(const struct scmi_device_id * id_table)196 scmi_protocol_table_unregister(const struct scmi_device_id *id_table)
197 {
198 const struct scmi_device_id *entry;
199
200 for (entry = id_table; entry->name; entry++)
201 scmi_protocol_device_unrequest(entry);
202 }
203
scmi_dev_match_by_id_table(struct scmi_device * scmi_dev,const struct scmi_device_id * id_table)204 static int scmi_dev_match_by_id_table(struct scmi_device *scmi_dev,
205 const struct scmi_device_id *id_table)
206 {
207 if (!id_table || !id_table->name)
208 return 0;
209
210 /* Always skip transport devices from matching */
211 for (; id_table->protocol_id && id_table->name; id_table++)
212 if (id_table->protocol_id == scmi_dev->protocol_id &&
213 strncmp(scmi_dev->name, "__scmi_transport_device", 23) &&
214 !strcmp(id_table->name, scmi_dev->name))
215 return 1;
216 return 0;
217 }
218
scmi_dev_match_id(struct scmi_device * scmi_dev,const struct scmi_driver * scmi_drv)219 static int scmi_dev_match_id(struct scmi_device *scmi_dev,
220 const struct scmi_driver *scmi_drv)
221 {
222 return scmi_dev_match_by_id_table(scmi_dev, scmi_drv->id_table);
223 }
224
scmi_dev_match(struct device * dev,const struct device_driver * drv)225 static int scmi_dev_match(struct device *dev, const struct device_driver *drv)
226 {
227 const struct scmi_driver *scmi_drv = to_scmi_driver(drv);
228 struct scmi_device *scmi_dev = to_scmi_dev(dev);
229
230 return scmi_dev_match_id(scmi_dev, scmi_drv);
231 }
232
scmi_match_by_id_table(struct device * dev,const void * data)233 static int scmi_match_by_id_table(struct device *dev, const void *data)
234 {
235 struct scmi_device *scmi_dev = to_scmi_dev(dev);
236 const struct scmi_device_id *id_table = data;
237
238 return scmi_dev_match_by_id_table(scmi_dev, id_table);
239 }
240
scmi_child_dev_find(struct device * parent,int prot_id,const char * name)241 static struct scmi_device *scmi_child_dev_find(struct device *parent,
242 int prot_id, const char *name)
243 {
244 struct scmi_device_id id_table[2] = { 0 };
245 struct device *dev;
246
247 id_table[0].protocol_id = prot_id;
248 id_table[0].name = name;
249
250 dev = device_find_child(parent, &id_table, scmi_match_by_id_table);
251 if (!dev)
252 return NULL;
253
254 /* Drop the refcnt bumped implicitly by device_find_child */
255 put_device(dev);
256
257 return to_scmi_dev(dev);
258 }
259
scmi_dev_probe(struct device * dev)260 static int scmi_dev_probe(struct device *dev)
261 {
262 struct scmi_driver *scmi_drv = to_scmi_driver(dev->driver);
263 struct scmi_device *scmi_dev = to_scmi_dev(dev);
264
265 if (!scmi_dev->handle)
266 return -EPROBE_DEFER;
267
268 return scmi_drv->probe(scmi_dev);
269 }
270
scmi_dev_remove(struct device * dev)271 static void scmi_dev_remove(struct device *dev)
272 {
273 struct scmi_driver *scmi_drv = to_scmi_driver(dev->driver);
274 struct scmi_device *scmi_dev = to_scmi_dev(dev);
275
276 if (scmi_drv->remove)
277 scmi_drv->remove(scmi_dev);
278 }
279
scmi_device_uevent(const struct device * dev,struct kobj_uevent_env * env)280 static int scmi_device_uevent(const struct device *dev, struct kobj_uevent_env *env)
281 {
282 const struct scmi_device *scmi_dev = to_scmi_dev(dev);
283
284 return add_uevent_var(env, "MODALIAS=" SCMI_UEVENT_MODALIAS_FMT,
285 dev_name(&scmi_dev->dev), scmi_dev->protocol_id,
286 scmi_dev->name);
287 }
288
modalias_show(struct device * dev,struct device_attribute * attr,char * buf)289 static ssize_t modalias_show(struct device *dev,
290 struct device_attribute *attr, char *buf)
291 {
292 struct scmi_device *scmi_dev = to_scmi_dev(dev);
293
294 return sysfs_emit(buf, SCMI_UEVENT_MODALIAS_FMT,
295 dev_name(&scmi_dev->dev), scmi_dev->protocol_id,
296 scmi_dev->name);
297 }
298 static DEVICE_ATTR_RO(modalias);
299
protocol_id_show(struct device * dev,struct device_attribute * attr,char * buf)300 static ssize_t protocol_id_show(struct device *dev,
301 struct device_attribute *attr, char *buf)
302 {
303 struct scmi_device *scmi_dev = to_scmi_dev(dev);
304
305 return sprintf(buf, "0x%02x\n", scmi_dev->protocol_id);
306 }
307 static DEVICE_ATTR_RO(protocol_id);
308
name_show(struct device * dev,struct device_attribute * attr,char * buf)309 static ssize_t name_show(struct device *dev, struct device_attribute *attr,
310 char *buf)
311 {
312 struct scmi_device *scmi_dev = to_scmi_dev(dev);
313
314 return sprintf(buf, "%s\n", scmi_dev->name);
315 }
316 static DEVICE_ATTR_RO(name);
317
318 static struct attribute *scmi_device_attributes_attrs[] = {
319 &dev_attr_protocol_id.attr,
320 &dev_attr_name.attr,
321 &dev_attr_modalias.attr,
322 NULL,
323 };
324 ATTRIBUTE_GROUPS(scmi_device_attributes);
325
scmi_pm_suspend(struct device * dev)326 static int scmi_pm_suspend(struct device *dev)
327 {
328 const struct device_driver *drv = dev->driver;
329
330 if (drv && drv->pm && drv->pm->suspend)
331 return drv->pm->suspend(dev);
332
333 return 0;
334 }
335
scmi_pm_resume(struct device * dev)336 static int scmi_pm_resume(struct device *dev)
337 {
338 const struct device_driver *drv = dev->driver;
339
340 if (drv && drv->pm && drv->pm->resume)
341 return drv->pm->resume(dev);
342
343 return 0;
344 }
345
346 static const struct dev_pm_ops scmi_dev_pm_ops = {
347 .suspend = pm_sleep_ptr(scmi_pm_suspend),
348 .resume = pm_sleep_ptr(scmi_pm_resume),
349 };
350
351 const struct bus_type scmi_bus_type = {
352 .name = "scmi_protocol",
353 .match = scmi_dev_match,
354 .probe = scmi_dev_probe,
355 .remove = scmi_dev_remove,
356 .uevent = scmi_device_uevent,
357 .dev_groups = scmi_device_attributes_groups,
358 .pm = &scmi_dev_pm_ops,
359 };
360 EXPORT_SYMBOL_GPL(scmi_bus_type);
361
scmi_driver_register(struct scmi_driver * driver,struct module * owner,const char * mod_name)362 int scmi_driver_register(struct scmi_driver *driver, struct module *owner,
363 const char *mod_name)
364 {
365 int retval;
366
367 if (!driver->probe)
368 return -EINVAL;
369
370 retval = scmi_protocol_table_register(driver->id_table);
371 if (retval)
372 return retval;
373
374 driver->driver.bus = &scmi_bus_type;
375 driver->driver.name = driver->name;
376 driver->driver.owner = owner;
377 driver->driver.mod_name = mod_name;
378
379 retval = driver_register(&driver->driver);
380 if (!retval)
381 pr_debug("Registered new scmi driver %s\n", driver->name);
382
383 return retval;
384 }
385 EXPORT_SYMBOL_GPL(scmi_driver_register);
386
scmi_driver_unregister(struct scmi_driver * driver)387 void scmi_driver_unregister(struct scmi_driver *driver)
388 {
389 driver_unregister(&driver->driver);
390 scmi_protocol_table_unregister(driver->id_table);
391 }
392 EXPORT_SYMBOL_GPL(scmi_driver_unregister);
393
scmi_device_release(struct device * dev)394 static void scmi_device_release(struct device *dev)
395 {
396 struct scmi_device *scmi_dev = to_scmi_dev(dev);
397
398 kfree_const(scmi_dev->name);
399 kfree(scmi_dev);
400 }
401
__scmi_device_destroy(struct scmi_device * scmi_dev)402 static void __scmi_device_destroy(struct scmi_device *scmi_dev)
403 {
404 pr_debug("(%s) Destroying SCMI device '%s' for protocol 0x%x (%s)\n",
405 of_node_full_name(scmi_dev->dev.parent->of_node),
406 dev_name(&scmi_dev->dev), scmi_dev->protocol_id,
407 scmi_dev->name);
408
409 if (scmi_dev->protocol_id == SCMI_PROTOCOL_SYSTEM)
410 atomic_set(&scmi_syspower_registered, 0);
411
412 ida_free(&scmi_bus_id, scmi_dev->id);
413 device_unregister(&scmi_dev->dev);
414 }
415
416 static struct scmi_device *
__scmi_device_create(struct device_node * np,struct device * parent,int protocol,const char * name)417 __scmi_device_create(struct device_node *np, struct device *parent,
418 int protocol, const char *name)
419 {
420 int id, retval;
421 struct scmi_device *scmi_dev;
422
423 /*
424 * If the same protocol/name device already exist under the same parent
425 * (i.e. SCMI instance) just return the existent device.
426 * This avoids any race between the SCMI driver, creating devices for
427 * each DT defined protocol at probe time, and the concurrent
428 * registration of SCMI drivers.
429 */
430 scmi_dev = scmi_child_dev_find(parent, protocol, name);
431 if (scmi_dev)
432 return scmi_dev;
433
434 /*
435 * Ignore any possible subsequent failures while creating the device
436 * since we are doomed anyway at that point; not using a mutex which
437 * spans across this whole function to keep things simple and to avoid
438 * to serialize all the __scmi_device_create calls across possibly
439 * different SCMI server instances (parent)
440 */
441 if (protocol == SCMI_PROTOCOL_SYSTEM &&
442 atomic_cmpxchg(&scmi_syspower_registered, 0, 1)) {
443 dev_warn(parent,
444 "SCMI SystemPower protocol device must be unique !\n");
445 return NULL;
446 }
447
448 scmi_dev = kzalloc(sizeof(*scmi_dev), GFP_KERNEL);
449 if (!scmi_dev)
450 return NULL;
451
452 scmi_dev->name = kstrdup_const(name ?: "unknown", GFP_KERNEL);
453 if (!scmi_dev->name) {
454 kfree(scmi_dev);
455 return NULL;
456 }
457
458 id = ida_alloc_min(&scmi_bus_id, 1, GFP_KERNEL);
459 if (id < 0) {
460 kfree_const(scmi_dev->name);
461 kfree(scmi_dev);
462 return NULL;
463 }
464
465 scmi_dev->id = id;
466 scmi_dev->protocol_id = protocol;
467 scmi_dev->dev.parent = parent;
468 device_set_node(&scmi_dev->dev, of_fwnode_handle(np));
469 scmi_dev->dev.bus = &scmi_bus_type;
470 scmi_dev->dev.release = scmi_device_release;
471 dev_set_name(&scmi_dev->dev, "scmi_dev.%d", id);
472
473 retval = device_register(&scmi_dev->dev);
474 if (retval)
475 goto put_dev;
476
477 pr_debug("(%s) Created SCMI device '%s' for protocol 0x%x (%s)\n",
478 of_node_full_name(parent->of_node),
479 dev_name(&scmi_dev->dev), protocol, name);
480
481 return scmi_dev;
482 put_dev:
483 put_device(&scmi_dev->dev);
484 ida_free(&scmi_bus_id, id);
485 return NULL;
486 }
487
488 static struct scmi_device *
_scmi_device_create(struct device_node * np,struct device * parent,int protocol,const char * name)489 _scmi_device_create(struct device_node *np, struct device *parent,
490 int protocol, const char *name)
491 {
492 struct scmi_device *sdev;
493
494 sdev = __scmi_device_create(np, parent, protocol, name);
495 if (!sdev)
496 pr_err("(%s) Failed to create device for protocol 0x%x (%s)\n",
497 of_node_full_name(parent->of_node), protocol, name);
498
499 return sdev;
500 }
501
502 /**
503 * scmi_device_create - A method to create one or more SCMI devices
504 *
505 * @np: A reference to the device node to use for the new device(s)
506 * @parent: The parent device to use identifying a specific SCMI instance
507 * @protocol: The SCMI protocol to be associated with this device
508 * @name: The requested-name of the device to be created; this is optional
509 * and if no @name is provided, all the devices currently known to
510 * be requested on the SCMI bus for @protocol will be created.
511 *
512 * This method can be invoked to create a single well-defined device (like
513 * a transport device or a device requested by an SCMI driver loaded after
514 * the core SCMI stack has been probed), or to create all the devices currently
515 * known to have been requested by the loaded SCMI drivers for a specific
516 * protocol (typically during SCMI core protocol enumeration at probe time).
517 *
518 * Return: The created device (or one of them if @name was NOT provided and
519 * multiple devices were created) or NULL if no device was created;
520 * note that NULL indicates an error ONLY in case a specific @name
521 * was provided: when @name param was not provided, a number of devices
522 * could have been potentially created for a whole protocol, unless no
523 * device was found to have been requested for that specific protocol.
524 */
scmi_device_create(struct device_node * np,struct device * parent,int protocol,const char * name)525 struct scmi_device *scmi_device_create(struct device_node *np,
526 struct device *parent, int protocol,
527 const char *name)
528 {
529 struct list_head *phead;
530 struct scmi_requested_dev *rdev;
531 struct scmi_device *scmi_dev = NULL;
532
533 if (name)
534 return _scmi_device_create(np, parent, protocol, name);
535
536 mutex_lock(&scmi_requested_devices_mtx);
537 phead = idr_find(&scmi_requested_devices, protocol);
538 /* Nothing to do. */
539 if (!phead) {
540 mutex_unlock(&scmi_requested_devices_mtx);
541 return NULL;
542 }
543
544 /* Walk the list of requested devices for protocol and create them */
545 list_for_each_entry(rdev, phead, node) {
546 struct scmi_device *sdev;
547
548 sdev = _scmi_device_create(np, parent,
549 rdev->id_table->protocol_id,
550 rdev->id_table->name);
551 if (sdev)
552 scmi_dev = sdev;
553 }
554
555 mutex_unlock(&scmi_requested_devices_mtx);
556
557 return scmi_dev;
558 }
559 EXPORT_SYMBOL_GPL(scmi_device_create);
560
scmi_device_destroy(struct device * parent,int protocol,const char * name)561 void scmi_device_destroy(struct device *parent, int protocol, const char *name)
562 {
563 struct scmi_device *scmi_dev;
564
565 scmi_dev = scmi_child_dev_find(parent, protocol, name);
566 if (scmi_dev)
567 __scmi_device_destroy(scmi_dev);
568 }
569 EXPORT_SYMBOL_GPL(scmi_device_destroy);
570
__scmi_devices_unregister(struct device * dev,void * data)571 static int __scmi_devices_unregister(struct device *dev, void *data)
572 {
573 struct scmi_device *scmi_dev = to_scmi_dev(dev);
574
575 __scmi_device_destroy(scmi_dev);
576 return 0;
577 }
578
scmi_devices_unregister(void)579 static void scmi_devices_unregister(void)
580 {
581 bus_for_each_dev(&scmi_bus_type, NULL, NULL, __scmi_devices_unregister);
582 }
583
scmi_bus_init(void)584 static int __init scmi_bus_init(void)
585 {
586 int retval;
587
588 retval = bus_register(&scmi_bus_type);
589 if (retval)
590 pr_err("SCMI protocol bus register failed (%d)\n", retval);
591
592 pr_info("SCMI protocol bus registered\n");
593
594 return retval;
595 }
596 subsys_initcall(scmi_bus_init);
597
scmi_bus_exit(void)598 static void __exit scmi_bus_exit(void)
599 {
600 /*
601 * Destroy all remaining devices: just in case the drivers were
602 * manually unbound and at first and then the modules unloaded.
603 */
604 scmi_devices_unregister();
605 bus_unregister(&scmi_bus_type);
606 ida_destroy(&scmi_bus_id);
607 }
608 module_exit(scmi_bus_exit);
609
610 MODULE_ALIAS("scmi-core");
611 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
612 MODULE_DESCRIPTION("ARM SCMI protocol bus");
613 MODULE_LICENSE("GPL");
614