1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * LED Triggers Core
4 *
5 * Copyright 2005-2007 Openedhand Ltd.
6 *
7 * Author: Richard Purdie <rpurdie@openedhand.com>
8 */
9
10 #include <linux/export.h>
11 #include <linux/kernel.h>
12 #include <linux/list.h>
13 #include <linux/spinlock.h>
14 #include <linux/device.h>
15 #include <linux/timer.h>
16 #include <linux/rwsem.h>
17 #include <linux/leds.h>
18 #include <linux/slab.h>
19 #include <linux/mm.h>
20 #include "leds.h"
21
22 /*
23 * Nests outside led_cdev->trigger_lock
24 */
25 static DECLARE_RWSEM(triggers_list_lock);
26 static LIST_HEAD(trigger_list);
27
28 /* Used by LED Class */
29
30 static inline bool
trigger_relevant(struct led_classdev * led_cdev,struct led_trigger * trig)31 trigger_relevant(struct led_classdev *led_cdev, struct led_trigger *trig)
32 {
33 return !trig->trigger_type || trig->trigger_type == led_cdev->trigger_type;
34 }
35
led_trigger_write(struct file * filp,struct kobject * kobj,const struct bin_attribute * bin_attr,char * buf,loff_t pos,size_t count)36 ssize_t led_trigger_write(struct file *filp, struct kobject *kobj,
37 const struct bin_attribute *bin_attr, char *buf,
38 loff_t pos, size_t count)
39 {
40 struct device *dev = kobj_to_dev(kobj);
41 struct led_classdev *led_cdev = dev_get_drvdata(dev);
42 struct led_trigger *trig;
43 int ret = count;
44
45 mutex_lock(&led_cdev->led_access);
46
47 if (led_sysfs_is_disabled(led_cdev)) {
48 ret = -EBUSY;
49 goto unlock;
50 }
51
52 if (sysfs_streq(buf, "none")) {
53 led_trigger_remove(led_cdev);
54 goto unlock;
55 }
56
57 if (sysfs_streq(buf, "default")) {
58 led_trigger_set_default(led_cdev);
59 goto unlock;
60 }
61
62 down_read(&triggers_list_lock);
63 list_for_each_entry(trig, &trigger_list, next_trig) {
64 if (sysfs_streq(buf, trig->name) && trigger_relevant(led_cdev, trig)) {
65 down_write(&led_cdev->trigger_lock);
66 led_trigger_set(led_cdev, trig);
67 up_write(&led_cdev->trigger_lock);
68
69 up_read(&triggers_list_lock);
70 goto unlock;
71 }
72 }
73 /* we come here only if buf matches no trigger */
74 ret = -EINVAL;
75 up_read(&triggers_list_lock);
76
77 unlock:
78 mutex_unlock(&led_cdev->led_access);
79 return ret;
80 }
81 EXPORT_SYMBOL_GPL(led_trigger_write);
82
83 __printf(3, 4)
led_trigger_snprintf(char * buf,ssize_t size,const char * fmt,...)84 static int led_trigger_snprintf(char *buf, ssize_t size, const char *fmt, ...)
85 {
86 va_list args;
87 int i;
88
89 va_start(args, fmt);
90 if (size <= 0)
91 i = vsnprintf(NULL, 0, fmt, args);
92 else
93 i = vscnprintf(buf, size, fmt, args);
94 va_end(args);
95
96 return i;
97 }
98
led_trigger_format(char * buf,size_t size,struct led_classdev * led_cdev)99 static int led_trigger_format(char *buf, size_t size,
100 struct led_classdev *led_cdev)
101 {
102 struct led_trigger *trig;
103 int len = led_trigger_snprintf(buf, size, "%s",
104 led_cdev->trigger ? "none" : "[none]");
105
106 if (led_cdev->default_trigger)
107 len += led_trigger_snprintf(buf + len, size - len, " default");
108
109 list_for_each_entry(trig, &trigger_list, next_trig) {
110 bool hit;
111
112 if (!trigger_relevant(led_cdev, trig))
113 continue;
114
115 hit = led_cdev->trigger && !strcmp(led_cdev->trigger->name, trig->name);
116
117 len += led_trigger_snprintf(buf + len, size - len,
118 " %s%s%s", hit ? "[" : "",
119 trig->name, hit ? "]" : "");
120 }
121
122 len += led_trigger_snprintf(buf + len, size - len, "\n");
123
124 return len;
125 }
126
127 /*
128 * It was stupid to create 10000 cpu triggers, but we are stuck with it now.
129 * Don't make that mistake again. We work around it here by creating binary
130 * attribute, which is not limited by length. This is _not_ good design, do not
131 * copy it.
132 */
led_trigger_read(struct file * filp,struct kobject * kobj,const struct bin_attribute * attr,char * buf,loff_t pos,size_t count)133 ssize_t led_trigger_read(struct file *filp, struct kobject *kobj,
134 const struct bin_attribute *attr, char *buf,
135 loff_t pos, size_t count)
136 {
137 struct device *dev = kobj_to_dev(kobj);
138 struct led_classdev *led_cdev = dev_get_drvdata(dev);
139 void *data;
140 int len;
141
142 down_read(&triggers_list_lock);
143 down_read(&led_cdev->trigger_lock);
144
145 len = led_trigger_format(NULL, 0, led_cdev);
146 data = kvmalloc(len + 1, GFP_KERNEL);
147 if (!data) {
148 up_read(&led_cdev->trigger_lock);
149 up_read(&triggers_list_lock);
150 return -ENOMEM;
151 }
152 len = led_trigger_format(data, len + 1, led_cdev);
153
154 up_read(&led_cdev->trigger_lock);
155 up_read(&triggers_list_lock);
156
157 len = memory_read_from_buffer(buf, count, &pos, data, len);
158
159 kvfree(data);
160
161 return len;
162 }
163 EXPORT_SYMBOL_GPL(led_trigger_read);
164
165 /* Caller must ensure led_cdev->trigger_lock held */
led_trigger_set(struct led_classdev * led_cdev,struct led_trigger * trig)166 int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
167 {
168 char *event = NULL;
169 char *envp[2];
170 const char *name;
171 int ret;
172
173 if (!led_cdev->trigger && !trig)
174 return 0;
175
176 name = trig ? trig->name : "none";
177 event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
178
179 /* Remove any existing trigger */
180 if (led_cdev->trigger) {
181 spin_lock(&led_cdev->trigger->leddev_list_lock);
182 list_del_rcu(&led_cdev->trig_list);
183 spin_unlock(&led_cdev->trigger->leddev_list_lock);
184
185 /* ensure it's no longer visible on the led_cdevs list */
186 synchronize_rcu();
187
188 cancel_work_sync(&led_cdev->set_brightness_work);
189 led_stop_software_blink(led_cdev);
190 device_remove_groups(led_cdev->dev, led_cdev->trigger->groups);
191 if (led_cdev->trigger->deactivate)
192 led_cdev->trigger->deactivate(led_cdev);
193 led_cdev->trigger = NULL;
194 led_cdev->trigger_data = NULL;
195 led_cdev->activated = false;
196 led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER;
197 led_set_brightness(led_cdev, LED_OFF);
198 }
199 if (trig) {
200 spin_lock(&trig->leddev_list_lock);
201 list_add_tail_rcu(&led_cdev->trig_list, &trig->led_cdevs);
202 spin_unlock(&trig->leddev_list_lock);
203 led_cdev->trigger = trig;
204
205 /*
206 * Some activate() calls use led_trigger_event() to initialize
207 * the brightness of the LED for which the trigger is being set.
208 * Ensure the led_cdev is visible on trig->led_cdevs for this.
209 */
210 synchronize_rcu();
211
212 /*
213 * If "set brightness to 0" is pending in workqueue,
214 * we don't want that to be reordered after ->activate()
215 */
216 flush_work(&led_cdev->set_brightness_work);
217
218 ret = 0;
219 if (trig->activate)
220 ret = trig->activate(led_cdev);
221 else
222 led_set_brightness(led_cdev, trig->brightness);
223 if (ret)
224 goto err_activate;
225
226 ret = device_add_groups(led_cdev->dev, trig->groups);
227 if (ret) {
228 dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
229 goto err_add_groups;
230 }
231 }
232
233 if (event) {
234 envp[0] = event;
235 envp[1] = NULL;
236 if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
237 dev_err(led_cdev->dev,
238 "%s: Error sending uevent\n", __func__);
239 kfree(event);
240 }
241
242 return 0;
243
244 err_add_groups:
245
246 if (trig->deactivate)
247 trig->deactivate(led_cdev);
248 err_activate:
249
250 spin_lock(&led_cdev->trigger->leddev_list_lock);
251 list_del_rcu(&led_cdev->trig_list);
252 spin_unlock(&led_cdev->trigger->leddev_list_lock);
253 synchronize_rcu();
254 led_cdev->trigger = NULL;
255 led_cdev->trigger_data = NULL;
256 led_set_brightness(led_cdev, LED_OFF);
257 kfree(event);
258
259 return ret;
260 }
261 EXPORT_SYMBOL_GPL(led_trigger_set);
262
led_trigger_remove(struct led_classdev * led_cdev)263 void led_trigger_remove(struct led_classdev *led_cdev)
264 {
265 down_write(&led_cdev->trigger_lock);
266 led_trigger_set(led_cdev, NULL);
267 up_write(&led_cdev->trigger_lock);
268 }
269 EXPORT_SYMBOL_GPL(led_trigger_remove);
270
led_match_default_trigger(struct led_classdev * led_cdev,struct led_trigger * trig)271 static bool led_match_default_trigger(struct led_classdev *led_cdev,
272 struct led_trigger *trig)
273 {
274 if (!strcmp(led_cdev->default_trigger, trig->name) &&
275 trigger_relevant(led_cdev, trig)) {
276 led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
277 led_trigger_set(led_cdev, trig);
278 return true;
279 }
280
281 return false;
282 }
283
led_trigger_set_default(struct led_classdev * led_cdev)284 void led_trigger_set_default(struct led_classdev *led_cdev)
285 {
286 struct led_trigger *trig;
287 bool found = false;
288
289 if (!led_cdev->default_trigger)
290 return;
291
292 if (!strcmp(led_cdev->default_trigger, "none")) {
293 led_trigger_remove(led_cdev);
294 return;
295 }
296
297 down_read(&triggers_list_lock);
298 down_write(&led_cdev->trigger_lock);
299 list_for_each_entry(trig, &trigger_list, next_trig) {
300 found = led_match_default_trigger(led_cdev, trig);
301 if (found)
302 break;
303 }
304 up_write(&led_cdev->trigger_lock);
305 up_read(&triggers_list_lock);
306
307 /*
308 * If default trigger wasn't found, maybe trigger module isn't loaded yet.
309 * Once loaded it will re-probe with all led_cdev's.
310 */
311 if (!found)
312 request_module_nowait("ledtrig:%s", led_cdev->default_trigger);
313 }
314 EXPORT_SYMBOL_GPL(led_trigger_set_default);
315
316 /* LED Trigger Interface */
317
led_trigger_register(struct led_trigger * trig)318 int led_trigger_register(struct led_trigger *trig)
319 {
320 struct led_classdev *led_cdev;
321 struct led_trigger *_trig;
322
323 spin_lock_init(&trig->leddev_list_lock);
324 INIT_LIST_HEAD(&trig->led_cdevs);
325
326 down_write(&triggers_list_lock);
327 /* Make sure the trigger's name isn't already in use */
328 list_for_each_entry(_trig, &trigger_list, next_trig) {
329 if (!strcmp(_trig->name, trig->name) &&
330 (trig->trigger_type == _trig->trigger_type ||
331 !trig->trigger_type || !_trig->trigger_type)) {
332 up_write(&triggers_list_lock);
333 return -EEXIST;
334 }
335 }
336 /* Add to the list of led triggers */
337 list_add_tail(&trig->next_trig, &trigger_list);
338 up_write(&triggers_list_lock);
339
340 /* Register with any LEDs that have this as a default trigger */
341 down_read(&leds_list_lock);
342 list_for_each_entry(led_cdev, &leds_list, node) {
343 down_write(&led_cdev->trigger_lock);
344 if (!led_cdev->trigger && led_cdev->default_trigger)
345 led_match_default_trigger(led_cdev, trig);
346 up_write(&led_cdev->trigger_lock);
347 }
348 up_read(&leds_list_lock);
349
350 return 0;
351 }
352 EXPORT_SYMBOL_GPL(led_trigger_register);
353
led_trigger_unregister(struct led_trigger * trig)354 void led_trigger_unregister(struct led_trigger *trig)
355 {
356 struct led_classdev *led_cdev;
357
358 if (list_empty_careful(&trig->next_trig))
359 return;
360
361 /* Remove from the list of led triggers */
362 down_write(&triggers_list_lock);
363 list_del_init(&trig->next_trig);
364 up_write(&triggers_list_lock);
365
366 /* Remove anyone actively using this trigger */
367 down_read(&leds_list_lock);
368 list_for_each_entry(led_cdev, &leds_list, node) {
369 down_write(&led_cdev->trigger_lock);
370 if (led_cdev->trigger == trig)
371 led_trigger_set(led_cdev, NULL);
372 up_write(&led_cdev->trigger_lock);
373 }
374 up_read(&leds_list_lock);
375 }
376 EXPORT_SYMBOL_GPL(led_trigger_unregister);
377
devm_led_trigger_release(struct device * dev,void * res)378 static void devm_led_trigger_release(struct device *dev, void *res)
379 {
380 led_trigger_unregister(*(struct led_trigger **)res);
381 }
382
devm_led_trigger_register(struct device * dev,struct led_trigger * trig)383 int devm_led_trigger_register(struct device *dev,
384 struct led_trigger *trig)
385 {
386 struct led_trigger **dr;
387 int rc;
388
389 dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
390 GFP_KERNEL);
391 if (!dr)
392 return -ENOMEM;
393
394 *dr = trig;
395
396 rc = led_trigger_register(trig);
397 if (rc)
398 devres_free(dr);
399 else
400 devres_add(dev, dr);
401
402 return rc;
403 }
404 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
405
406 /* Simple LED Trigger Interface */
407
led_trigger_event(struct led_trigger * trig,enum led_brightness brightness)408 void led_trigger_event(struct led_trigger *trig,
409 enum led_brightness brightness)
410 {
411 struct led_classdev *led_cdev;
412
413 if (!trig)
414 return;
415
416 trig->brightness = brightness;
417
418 rcu_read_lock();
419 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
420 led_set_brightness(led_cdev, brightness);
421 rcu_read_unlock();
422 }
423 EXPORT_SYMBOL_GPL(led_trigger_event);
424
led_mc_trigger_event(struct led_trigger * trig,unsigned int * intensity_value,unsigned int num_colors,enum led_brightness brightness)425 void led_mc_trigger_event(struct led_trigger *trig,
426 unsigned int *intensity_value, unsigned int num_colors,
427 enum led_brightness brightness)
428 {
429 struct led_classdev *led_cdev;
430
431 if (!trig)
432 return;
433
434 rcu_read_lock();
435 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
436 if (!(led_cdev->flags & LED_MULTI_COLOR))
437 continue;
438
439 led_mc_set_brightness(led_cdev, intensity_value, num_colors, brightness);
440 }
441 rcu_read_unlock();
442 }
443 EXPORT_SYMBOL_GPL(led_mc_trigger_event);
444
led_trigger_blink_setup(struct led_trigger * trig,unsigned long delay_on,unsigned long delay_off,int oneshot,int invert)445 static void led_trigger_blink_setup(struct led_trigger *trig,
446 unsigned long delay_on,
447 unsigned long delay_off,
448 int oneshot,
449 int invert)
450 {
451 struct led_classdev *led_cdev;
452
453 if (!trig)
454 return;
455
456 rcu_read_lock();
457 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
458 if (oneshot)
459 led_blink_set_oneshot(led_cdev, &delay_on, &delay_off,
460 invert);
461 else
462 led_blink_set_nosleep(led_cdev, delay_on, delay_off);
463 }
464 rcu_read_unlock();
465 }
466
led_trigger_blink(struct led_trigger * trig,unsigned long delay_on,unsigned long delay_off)467 void led_trigger_blink(struct led_trigger *trig,
468 unsigned long delay_on,
469 unsigned long delay_off)
470 {
471 led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
472 }
473 EXPORT_SYMBOL_GPL(led_trigger_blink);
474
led_trigger_blink_oneshot(struct led_trigger * trig,unsigned long delay_on,unsigned long delay_off,int invert)475 void led_trigger_blink_oneshot(struct led_trigger *trig,
476 unsigned long delay_on,
477 unsigned long delay_off,
478 int invert)
479 {
480 led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
481 }
482 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
483
led_trigger_register_simple(const char * name,struct led_trigger ** tp)484 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
485 {
486 struct led_trigger *trig;
487 int err;
488
489 trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
490
491 if (trig) {
492 trig->name = name;
493 err = led_trigger_register(trig);
494 if (err < 0) {
495 kfree(trig);
496 trig = NULL;
497 pr_warn("LED trigger %s failed to register (%d)\n",
498 name, err);
499 }
500 } else {
501 pr_warn("LED trigger %s failed to register (no memory)\n",
502 name);
503 }
504 *tp = trig;
505 }
506 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
507
led_trigger_unregister_simple(struct led_trigger * trig)508 void led_trigger_unregister_simple(struct led_trigger *trig)
509 {
510 if (trig)
511 led_trigger_unregister(trig);
512 kfree(trig);
513 }
514 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
515