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 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
250static bool led_match_default_trigger(struct led_classdev *led_cdev,
251 struct led_trigger *trig)
252{
253 if (!strcmp(led_cdev->default_trigger, trig->name) &&
254 trigger_relevant(led_cdev, trig)) {
255 led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
256 led_trigger_set(led_cdev, trig);
257 return true;
258 }
259
260 return false;
261}
262
263void led_trigger_set_default(struct led_classdev *led_cdev)
264{
265 struct led_trigger *trig;
266 bool found = false;
267
268 if (!led_cdev->default_trigger)
269 return;
270
271 down_read(sem: &triggers_list_lock);
272 down_write(sem: &led_cdev->trigger_lock);
273 list_for_each_entry(trig, &trigger_list, next_trig) {
274 found = led_match_default_trigger(led_cdev, trig);
275 if (found)
276 break;
277 }
278 up_write(sem: &led_cdev->trigger_lock);
279 up_read(sem: &triggers_list_lock);
280
281 /*
282 * If default trigger wasn't found, maybe trigger module isn't loaded yet.
283 * Once loaded it will re-probe with all led_cdev's.
284 */
285 if (!found)
286 request_module_nowait("ledtrig:%s", led_cdev->default_trigger);
287}
288EXPORT_SYMBOL_GPL(led_trigger_set_default);
289
290/* LED Trigger Interface */
291
292int led_trigger_register(struct led_trigger *trig)
293{
294 struct led_classdev *led_cdev;
295 struct led_trigger *_trig;
296
297 spin_lock_init(&trig->leddev_list_lock);
298 INIT_LIST_HEAD(list: &trig->led_cdevs);
299
300 down_write(sem: &triggers_list_lock);
301 /* Make sure the trigger's name isn't already in use */
302 list_for_each_entry(_trig, &trigger_list, next_trig) {
303 if (!strcmp(_trig->name, trig->name) &&
304 (trig->trigger_type == _trig->trigger_type ||
305 !trig->trigger_type || !_trig->trigger_type)) {
306 up_write(sem: &triggers_list_lock);
307 return -EEXIST;
308 }
309 }
310 /* Add to the list of led triggers */
311 list_add_tail(new: &trig->next_trig, head: &trigger_list);
312 up_write(sem: &triggers_list_lock);
313
314 /* Register with any LEDs that have this as a default trigger */
315 down_read(sem: &leds_list_lock);
316 list_for_each_entry(led_cdev, &leds_list, node) {
317 down_write(sem: &led_cdev->trigger_lock);
318 if (!led_cdev->trigger && led_cdev->default_trigger)
319 led_match_default_trigger(led_cdev, trig);
320 up_write(sem: &led_cdev->trigger_lock);
321 }
322 up_read(sem: &leds_list_lock);
323
324 return 0;
325}
326EXPORT_SYMBOL_GPL(led_trigger_register);
327
328void led_trigger_unregister(struct led_trigger *trig)
329{
330 struct led_classdev *led_cdev;
331
332 if (list_empty_careful(head: &trig->next_trig))
333 return;
334
335 /* Remove from the list of led triggers */
336 down_write(sem: &triggers_list_lock);
337 list_del_init(entry: &trig->next_trig);
338 up_write(sem: &triggers_list_lock);
339
340 /* Remove anyone actively using this 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 == trig)
345 led_trigger_set(led_cdev, NULL);
346 up_write(sem: &led_cdev->trigger_lock);
347 }
348 up_read(sem: &leds_list_lock);
349}
350EXPORT_SYMBOL_GPL(led_trigger_unregister);
351
352static void devm_led_trigger_release(struct device *dev, void *res)
353{
354 led_trigger_unregister(*(struct led_trigger **)res);
355}
356
357int devm_led_trigger_register(struct device *dev,
358 struct led_trigger *trig)
359{
360 struct led_trigger **dr;
361 int rc;
362
363 dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
364 GFP_KERNEL);
365 if (!dr)
366 return -ENOMEM;
367
368 *dr = trig;
369
370 rc = led_trigger_register(trig);
371 if (rc)
372 devres_free(res: dr);
373 else
374 devres_add(dev, res: dr);
375
376 return rc;
377}
378EXPORT_SYMBOL_GPL(devm_led_trigger_register);
379
380/* Simple LED Trigger Interface */
381
382void led_trigger_event(struct led_trigger *trig,
383 enum led_brightness brightness)
384{
385 struct led_classdev *led_cdev;
386
387 if (!trig)
388 return;
389
390 rcu_read_lock();
391 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
392 led_set_brightness(led_cdev, brightness);
393 rcu_read_unlock();
394}
395EXPORT_SYMBOL_GPL(led_trigger_event);
396
397static void led_trigger_blink_setup(struct led_trigger *trig,
398 unsigned long delay_on,
399 unsigned long delay_off,
400 int oneshot,
401 int invert)
402{
403 struct led_classdev *led_cdev;
404
405 if (!trig)
406 return;
407
408 rcu_read_lock();
409 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
410 if (oneshot)
411 led_blink_set_oneshot(led_cdev, delay_on: &delay_on, delay_off: &delay_off,
412 invert);
413 else
414 led_blink_set_nosleep(led_cdev, delay_on, delay_off);
415 }
416 rcu_read_unlock();
417}
418
419void led_trigger_blink(struct led_trigger *trig,
420 unsigned long delay_on,
421 unsigned long delay_off)
422{
423 led_trigger_blink_setup(trig, delay_on, delay_off, oneshot: 0, invert: 0);
424}
425EXPORT_SYMBOL_GPL(led_trigger_blink);
426
427void led_trigger_blink_oneshot(struct led_trigger *trig,
428 unsigned long delay_on,
429 unsigned long delay_off,
430 int invert)
431{
432 led_trigger_blink_setup(trig, delay_on, delay_off, oneshot: 1, invert);
433}
434EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
435
436void led_trigger_register_simple(const char *name, struct led_trigger **tp)
437{
438 struct led_trigger *trig;
439 int err;
440
441 trig = kzalloc(size: sizeof(struct led_trigger), GFP_KERNEL);
442
443 if (trig) {
444 trig->name = name;
445 err = led_trigger_register(trig);
446 if (err < 0) {
447 kfree(objp: trig);
448 trig = NULL;
449 pr_warn("LED trigger %s failed to register (%d)\n",
450 name, err);
451 }
452 } else {
453 pr_warn("LED trigger %s failed to register (no memory)\n",
454 name);
455 }
456 *tp = trig;
457}
458EXPORT_SYMBOL_GPL(led_trigger_register_simple);
459
460void led_trigger_unregister_simple(struct led_trigger *trig)
461{
462 if (trig)
463 led_trigger_unregister(trig);
464 kfree(objp: trig);
465}
466EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
467

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