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 */
25static DECLARE_RWSEM(triggers_list_lock);
26static LIST_HEAD(trigger_list);
27
28 /* Used by LED Class */
29
30static inline bool
31trigger_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
36ssize_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(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(s1: buf, s2: "none")) {
53 led_trigger_remove(led_cdev);
54 goto unlock;
55 }
56
57 if (sysfs_streq(s1: buf, s2: "default")) {
58 led_trigger_set_default(led_cdev);
59 goto unlock;
60 }
61
62 down_read(sem: &triggers_list_lock);
63 list_for_each_entry(trig, &trigger_list, next_trig) {
64 if (sysfs_streq(s1: buf, s2: trig->name) && trigger_relevant(led_cdev, trig)) {
65 down_write(sem: &led_cdev->trigger_lock);
66 led_trigger_set(led_cdev, trigger: trig);
67 up_write(sem: &led_cdev->trigger_lock);
68
69 up_read(sem: &triggers_list_lock);
70 goto unlock;
71 }
72 }
73 /* we come here only if buf matches no trigger */
74 ret = -EINVAL;
75 up_read(sem: &triggers_list_lock);
76
77unlock:
78 mutex_unlock(lock: &led_cdev->led_access);
79 return ret;
80}
81EXPORT_SYMBOL_GPL(led_trigger_write);
82
83__printf(3, 4)
84static 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, size: 0, fmt, args);
92 else
93 i = vscnprintf(buf, size, fmt, args);
94 va_end(args);
95
96 return i;
97}
98
99static 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, fmt: "%s",
104 led_cdev->trigger ? "none" : "[none]");
105
106 if (led_cdev->default_trigger)
107 len += led_trigger_snprintf(buf: buf + len, size: size - len, fmt: " 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: buf + len, size: size - len,
118 fmt: " %s%s%s", hit ? "[" : "",
119 trig->name, hit ? "]" : "");
120 }
121
122 len += led_trigger_snprintf(buf: buf + len, size: size - len, fmt: "\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 */
133ssize_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(sem: &triggers_list_lock);
143 down_read(sem: &led_cdev->trigger_lock);
144
145 len = led_trigger_format(NULL, size: 0, led_cdev);
146 data = kvmalloc(len + 1, GFP_KERNEL);
147 if (!data) {
148 up_read(sem: &led_cdev->trigger_lock);
149 up_read(sem: &triggers_list_lock);
150 return -ENOMEM;
151 }
152 len = led_trigger_format(buf: data, size: len + 1, led_cdev);
153
154 up_read(sem: &led_cdev->trigger_lock);
155 up_read(sem: &triggers_list_lock);
156
157 len = memory_read_from_buffer(to: buf, count, ppos: &pos, from: data, available: len);
158
159 kvfree(addr: data);
160
161 return len;
162}
163EXPORT_SYMBOL_GPL(led_trigger_read);
164
165/* Caller must ensure led_cdev->trigger_lock held */
166int 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, fmt: "TRIGGER=%s", name);
178
179 /* Remove any existing trigger */
180 if (led_cdev->trigger) {
181 spin_lock(lock: &led_cdev->trigger->leddev_list_lock);
182 list_del_rcu(entry: &led_cdev->trig_list);
183 spin_unlock(lock: &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(work: &led_cdev->set_brightness_work);
189 led_stop_software_blink(led_cdev);
190 device_remove_groups(dev: led_cdev->dev, groups: 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, brightness: LED_OFF);
198 }
199 if (trig) {
200 spin_lock(lock: &trig->leddev_list_lock);
201 list_add_tail_rcu(new: &led_cdev->trig_list, head: &trig->led_cdevs);
202 spin_unlock(lock: &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(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, brightness: trig->brightness);
223 if (ret)
224 goto err_activate;
225
226 ret = device_add_groups(dev: led_cdev->dev, groups: 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(kobj: &led_cdev->dev->kobj, action: KOBJ_CHANGE, envp))
237 dev_err(led_cdev->dev,
238 "%s: Error sending uevent\n", __func__);
239 kfree(objp: event);
240 }
241
242 return 0;
243
244err_add_groups:
245
246 if (trig->deactivate)
247 trig->deactivate(led_cdev);
248err_activate:
249
250 spin_lock(lock: &led_cdev->trigger->leddev_list_lock);
251 list_del_rcu(entry: &led_cdev->trig_list);
252 spin_unlock(lock: &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, brightness: LED_OFF);
257 kfree(objp: event);
258
259 return ret;
260}
261EXPORT_SYMBOL_GPL(led_trigger_set);
262
263void led_trigger_remove(struct led_classdev *led_cdev)
264{
265 down_write(sem: &led_cdev->trigger_lock);
266 led_trigger_set(led_cdev, NULL);
267 up_write(sem: &led_cdev->trigger_lock);
268}
269EXPORT_SYMBOL_GPL(led_trigger_remove);
270
271static 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
284void 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(sem: &triggers_list_lock);
298 down_write(sem: &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(sem: &led_cdev->trigger_lock);
305 up_read(sem: &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}
314EXPORT_SYMBOL_GPL(led_trigger_set_default);
315
316/* LED Trigger Interface */
317
318int 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(list: &trig->led_cdevs);
325
326 down_write(sem: &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(sem: &triggers_list_lock);
333 return -EEXIST;
334 }
335 }
336 /* Add to the list of led triggers */
337 list_add_tail(new: &trig->next_trig, head: &trigger_list);
338 up_write(sem: &triggers_list_lock);
339
340 /* Register with any LEDs that have this as a default trigger */
341 down_read(sem: &leds_list_lock);
342 list_for_each_entry(led_cdev, &leds_list, node) {
343 down_write(sem: &led_cdev->trigger_lock);
344 if (!led_cdev->trigger && led_cdev->default_trigger)
345 led_match_default_trigger(led_cdev, trig);
346 up_write(sem: &led_cdev->trigger_lock);
347 }
348 up_read(sem: &leds_list_lock);
349
350 return 0;
351}
352EXPORT_SYMBOL_GPL(led_trigger_register);
353
354void led_trigger_unregister(struct led_trigger *trig)
355{
356 struct led_classdev *led_cdev;
357
358 if (list_empty_careful(head: &trig->next_trig))
359 return;
360
361 /* Remove from the list of led triggers */
362 down_write(sem: &triggers_list_lock);
363 list_del_init(entry: &trig->next_trig);
364 up_write(sem: &triggers_list_lock);
365
366 /* Remove anyone actively using this trigger */
367 down_read(sem: &leds_list_lock);
368 list_for_each_entry(led_cdev, &leds_list, node) {
369 down_write(sem: &led_cdev->trigger_lock);
370 if (led_cdev->trigger == trig)
371 led_trigger_set(led_cdev, NULL);
372 up_write(sem: &led_cdev->trigger_lock);
373 }
374 up_read(sem: &leds_list_lock);
375}
376EXPORT_SYMBOL_GPL(led_trigger_unregister);
377
378static void devm_led_trigger_release(struct device *dev, void *res)
379{
380 led_trigger_unregister(*(struct led_trigger **)res);
381}
382
383int 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(res: dr);
399 else
400 devres_add(dev, res: dr);
401
402 return rc;
403}
404EXPORT_SYMBOL_GPL(devm_led_trigger_register);
405
406/* Simple LED Trigger Interface */
407
408void 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}
423EXPORT_SYMBOL_GPL(led_trigger_event);
424
425void 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}
443EXPORT_SYMBOL_GPL(led_mc_trigger_event);
444
445static 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_on, delay_off: &delay_off,
460 invert);
461 else
462 led_blink_set_nosleep(led_cdev, delay_on, delay_off);
463 }
464 rcu_read_unlock();
465}
466
467void 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, oneshot: 0, invert: 0);
472}
473EXPORT_SYMBOL_GPL(led_trigger_blink);
474
475void 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, oneshot: 1, invert);
481}
482EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
483
484void 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(objp: 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}
506EXPORT_SYMBOL_GPL(led_trigger_register_simple);
507
508void led_trigger_unregister_simple(struct led_trigger *trig)
509{
510 if (trig)
511 led_trigger_unregister(trig);
512 kfree(objp: trig);
513}
514EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
515