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);
26LIST_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 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(s1: buf, s2: "none")) {
53 led_trigger_remove(led_cdev);
54 goto unlock;
55 }
56
57 down_read(sem: &triggers_list_lock);
58 list_for_each_entry(trig, &trigger_list, next_trig) {
59 if (sysfs_streq(s1: buf, s2: trig->name) && trigger_relevant(led_cdev, trig)) {
60 down_write(sem: &led_cdev->trigger_lock);
61 led_trigger_set(led_cdev, trigger: trig);
62 up_write(sem: &led_cdev->trigger_lock);
63
64 up_read(sem: &triggers_list_lock);
65 goto unlock;
66 }
67 }
68 /* we come here only if buf matches no trigger */
69 ret = -EINVAL;
70 up_read(sem: &triggers_list_lock);
71
72unlock:
73 mutex_unlock(lock: &led_cdev->led_access);
74 return ret;
75}
76EXPORT_SYMBOL_GPL(led_trigger_write);
77
78__printf(3, 4)
79static int led_trigger_snprintf(char *buf, ssize_t size, const char *fmt, ...)
80{
81 va_list args;
82 int i;
83
84 va_start(args, fmt);
85 if (size <= 0)
86 i = vsnprintf(NULL, size: 0, fmt, args);
87 else
88 i = vscnprintf(buf, size, fmt, args);
89 va_end(args);
90
91 return i;
92}
93
94static int led_trigger_format(char *buf, size_t size,
95 struct led_classdev *led_cdev)
96{
97 struct led_trigger *trig;
98 int len = led_trigger_snprintf(buf, size, fmt: "%s",
99 led_cdev->trigger ? "none" : "[none]");
100
101 list_for_each_entry(trig, &trigger_list, next_trig) {
102 bool hit;
103
104 if (!trigger_relevant(led_cdev, trig))
105 continue;
106
107 hit = led_cdev->trigger && !strcmp(led_cdev->trigger->name, trig->name);
108
109 len += led_trigger_snprintf(buf: buf + len, size: size - len,
110 fmt: " %s%s%s", hit ? "[" : "",
111 trig->name, hit ? "]" : "");
112 }
113
114 len += led_trigger_snprintf(buf: buf + len, size: size - len, fmt: "\n");
115
116 return len;
117}
118
119/*
120 * It was stupid to create 10000 cpu triggers, but we are stuck with it now.
121 * Don't make that mistake again. We work around it here by creating binary
122 * attribute, which is not limited by length. This is _not_ good design, do not
123 * copy it.
124 */
125ssize_t led_trigger_read(struct file *filp, struct kobject *kobj,
126 struct bin_attribute *attr, char *buf,
127 loff_t pos, size_t count)
128{
129 struct device *dev = kobj_to_dev(kobj);
130 struct led_classdev *led_cdev = dev_get_drvdata(dev);
131 void *data;
132 int len;
133
134 down_read(sem: &triggers_list_lock);
135 down_read(sem: &led_cdev->trigger_lock);
136
137 len = led_trigger_format(NULL, size: 0, led_cdev);
138 data = kvmalloc(size: len + 1, GFP_KERNEL);
139 if (!data) {
140 up_read(sem: &led_cdev->trigger_lock);
141 up_read(sem: &triggers_list_lock);
142 return -ENOMEM;
143 }
144 len = led_trigger_format(buf: data, size: len + 1, led_cdev);
145
146 up_read(sem: &led_cdev->trigger_lock);
147 up_read(sem: &triggers_list_lock);
148
149 len = memory_read_from_buffer(to: buf, count, ppos: &pos, from: data, available: len);
150
151 kvfree(addr: data);
152
153 return len;
154}
155EXPORT_SYMBOL_GPL(led_trigger_read);
156
157/* Caller must ensure led_cdev->trigger_lock held */
158int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
159{
160 char *event = NULL;
161 char *envp[2];
162 const char *name;
163 int ret;
164
165 if (!led_cdev->trigger && !trig)
166 return 0;
167
168 name = trig ? trig->name : "none";
169 event = kasprintf(GFP_KERNEL, fmt: "TRIGGER=%s", name);
170
171 /* Remove any existing trigger */
172 if (led_cdev->trigger) {
173 spin_lock(lock: &led_cdev->trigger->leddev_list_lock);
174 list_del_rcu(entry: &led_cdev->trig_list);
175 spin_unlock(lock: &led_cdev->trigger->leddev_list_lock);
176
177 /* ensure it's no longer visible on the led_cdevs list */
178 synchronize_rcu();
179
180 cancel_work_sync(work: &led_cdev->set_brightness_work);
181 led_stop_software_blink(led_cdev);
182 if (led_cdev->trigger->deactivate)
183 led_cdev->trigger->deactivate(led_cdev);
184 device_remove_groups(dev: led_cdev->dev, groups: led_cdev->trigger->groups);
185 led_cdev->trigger = NULL;
186 led_cdev->trigger_data = NULL;
187 led_cdev->activated = false;
188 led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER;
189 led_set_brightness(led_cdev, brightness: LED_OFF);
190 }
191 if (trig) {
192 spin_lock(lock: &trig->leddev_list_lock);
193 list_add_tail_rcu(new: &led_cdev->trig_list, head: &trig->led_cdevs);
194 spin_unlock(lock: &trig->leddev_list_lock);
195 led_cdev->trigger = trig;
196
197 if (trig->activate)
198 ret = trig->activate(led_cdev);
199 else
200 ret = 0;
201
202 if (ret)
203 goto err_activate;
204
205 ret = device_add_groups(dev: led_cdev->dev, groups: trig->groups);
206 if (ret) {
207 dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
208 goto err_add_groups;
209 }
210 }
211
212 if (event) {
213 envp[0] = event;
214 envp[1] = NULL;
215 if (kobject_uevent_env(kobj: &led_cdev->dev->kobj, action: KOBJ_CHANGE, envp))
216 dev_err(led_cdev->dev,
217 "%s: Error sending uevent\n", __func__);
218 kfree(objp: event);
219 }
220
221 return 0;
222
223err_add_groups:
224
225 if (trig->deactivate)
226 trig->deactivate(led_cdev);
227err_activate:
228
229 spin_lock(lock: &led_cdev->trigger->leddev_list_lock);
230 list_del_rcu(entry: &led_cdev->trig_list);
231 spin_unlock(lock: &led_cdev->trigger->leddev_list_lock);
232 synchronize_rcu();
233 led_cdev->trigger = NULL;
234 led_cdev->trigger_data = NULL;
235 led_set_brightness(led_cdev, brightness: LED_OFF);
236 kfree(objp: event);
237
238 return ret;
239}
240EXPORT_SYMBOL_GPL(led_trigger_set);
241
242void led_trigger_remove(struct led_classdev *led_cdev)
243{
244 down_write(sem: &led_cdev->trigger_lock);
245 led_trigger_set(led_cdev, NULL);
246 up_write(sem: &led_cdev->trigger_lock);
247}
248EXPORT_SYMBOL_GPL(led_trigger_remove);
249
250void led_trigger_set_default(struct led_classdev *led_cdev)
251{
252 struct led_trigger *trig;
253
254 if (!led_cdev->default_trigger)
255 return;
256
257 down_read(sem: &triggers_list_lock);
258 down_write(sem: &led_cdev->trigger_lock);
259 list_for_each_entry(trig, &trigger_list, next_trig) {
260 if (!strcmp(led_cdev->default_trigger, trig->name) &&
261 trigger_relevant(led_cdev, trig)) {
262 led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
263 led_trigger_set(led_cdev, trig);
264 break;
265 }
266 }
267 up_write(sem: &led_cdev->trigger_lock);
268 up_read(sem: &triggers_list_lock);
269}
270EXPORT_SYMBOL_GPL(led_trigger_set_default);
271
272void led_trigger_rename_static(const char *name, struct led_trigger *trig)
273{
274 /* new name must be on a temporary string to prevent races */
275 BUG_ON(name == trig->name);
276
277 down_write(sem: &triggers_list_lock);
278 /* this assumes that trig->name was originaly allocated to
279 * non constant storage */
280 strcpy(p: (char *)trig->name, q: name);
281 up_write(sem: &triggers_list_lock);
282}
283EXPORT_SYMBOL_GPL(led_trigger_rename_static);
284
285/* LED Trigger Interface */
286
287int led_trigger_register(struct led_trigger *trig)
288{
289 struct led_classdev *led_cdev;
290 struct led_trigger *_trig;
291
292 spin_lock_init(&trig->leddev_list_lock);
293 INIT_LIST_HEAD(list: &trig->led_cdevs);
294
295 down_write(sem: &triggers_list_lock);
296 /* Make sure the trigger's name isn't already in use */
297 list_for_each_entry(_trig, &trigger_list, next_trig) {
298 if (!strcmp(_trig->name, trig->name) &&
299 (trig->trigger_type == _trig->trigger_type ||
300 !trig->trigger_type || !_trig->trigger_type)) {
301 up_write(sem: &triggers_list_lock);
302 return -EEXIST;
303 }
304 }
305 /* Add to the list of led triggers */
306 list_add_tail(new: &trig->next_trig, head: &trigger_list);
307 up_write(sem: &triggers_list_lock);
308
309 /* Register with any LEDs that have this as a default trigger */
310 down_read(sem: &leds_list_lock);
311 list_for_each_entry(led_cdev, &leds_list, node) {
312 down_write(sem: &led_cdev->trigger_lock);
313 if (!led_cdev->trigger && led_cdev->default_trigger &&
314 !strcmp(led_cdev->default_trigger, trig->name) &&
315 trigger_relevant(led_cdev, trig)) {
316 led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
317 led_trigger_set(led_cdev, trig);
318 }
319 up_write(sem: &led_cdev->trigger_lock);
320 }
321 up_read(sem: &leds_list_lock);
322
323 return 0;
324}
325EXPORT_SYMBOL_GPL(led_trigger_register);
326
327void led_trigger_unregister(struct led_trigger *trig)
328{
329 struct led_classdev *led_cdev;
330
331 if (list_empty_careful(head: &trig->next_trig))
332 return;
333
334 /* Remove from the list of led triggers */
335 down_write(sem: &triggers_list_lock);
336 list_del_init(entry: &trig->next_trig);
337 up_write(sem: &triggers_list_lock);
338
339 /* Remove anyone actively using this trigger */
340 down_read(sem: &leds_list_lock);
341 list_for_each_entry(led_cdev, &leds_list, node) {
342 down_write(sem: &led_cdev->trigger_lock);
343 if (led_cdev->trigger == trig)
344 led_trigger_set(led_cdev, NULL);
345 up_write(sem: &led_cdev->trigger_lock);
346 }
347 up_read(sem: &leds_list_lock);
348}
349EXPORT_SYMBOL_GPL(led_trigger_unregister);
350
351static void devm_led_trigger_release(struct device *dev, void *res)
352{
353 led_trigger_unregister(*(struct led_trigger **)res);
354}
355
356int devm_led_trigger_register(struct device *dev,
357 struct led_trigger *trig)
358{
359 struct led_trigger **dr;
360 int rc;
361
362 dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
363 GFP_KERNEL);
364 if (!dr)
365 return -ENOMEM;
366
367 *dr = trig;
368
369 rc = led_trigger_register(trig);
370 if (rc)
371 devres_free(res: dr);
372 else
373 devres_add(dev, res: dr);
374
375 return rc;
376}
377EXPORT_SYMBOL_GPL(devm_led_trigger_register);
378
379/* Simple LED Trigger Interface */
380
381void led_trigger_event(struct led_trigger *trig,
382 enum led_brightness brightness)
383{
384 struct led_classdev *led_cdev;
385
386 if (!trig)
387 return;
388
389 rcu_read_lock();
390 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
391 led_set_brightness(led_cdev, brightness);
392 rcu_read_unlock();
393}
394EXPORT_SYMBOL_GPL(led_trigger_event);
395
396static void led_trigger_blink_setup(struct led_trigger *trig,
397 unsigned long delay_on,
398 unsigned long delay_off,
399 int oneshot,
400 int invert)
401{
402 struct led_classdev *led_cdev;
403
404 if (!trig)
405 return;
406
407 rcu_read_lock();
408 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
409 if (oneshot)
410 led_blink_set_oneshot(led_cdev, delay_on: &delay_on, delay_off: &delay_off,
411 invert);
412 else
413 led_blink_set_nosleep(led_cdev, delay_on, delay_off);
414 }
415 rcu_read_unlock();
416}
417
418void led_trigger_blink(struct led_trigger *trig,
419 unsigned long delay_on,
420 unsigned long delay_off)
421{
422 led_trigger_blink_setup(trig, delay_on, delay_off, oneshot: 0, invert: 0);
423}
424EXPORT_SYMBOL_GPL(led_trigger_blink);
425
426void led_trigger_blink_oneshot(struct led_trigger *trig,
427 unsigned long delay_on,
428 unsigned long delay_off,
429 int invert)
430{
431 led_trigger_blink_setup(trig, delay_on, delay_off, oneshot: 1, invert);
432}
433EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
434
435void led_trigger_register_simple(const char *name, struct led_trigger **tp)
436{
437 struct led_trigger *trig;
438 int err;
439
440 trig = kzalloc(size: sizeof(struct led_trigger), GFP_KERNEL);
441
442 if (trig) {
443 trig->name = name;
444 err = led_trigger_register(trig);
445 if (err < 0) {
446 kfree(objp: trig);
447 trig = NULL;
448 pr_warn("LED trigger %s failed to register (%d)\n",
449 name, err);
450 }
451 } else {
452 pr_warn("LED trigger %s failed to register (no memory)\n",
453 name);
454 }
455 *tp = trig;
456}
457EXPORT_SYMBOL_GPL(led_trigger_register_simple);
458
459void led_trigger_unregister_simple(struct led_trigger *trig)
460{
461 if (trig)
462 led_trigger_unregister(trig);
463 kfree(objp: trig);
464}
465EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
466

source code of linux/drivers/leds/led-triggers.c