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 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,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 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 down_read(&triggers_list_lock);
58 list_for_each_entry(trig, &trigger_list, next_trig) {
59 if (sysfs_streq(buf, trig->name) && trigger_relevant(led_cdev, trig)) {
60 down_write(&led_cdev->trigger_lock);
61 led_trigger_set(led_cdev, trig);
62 up_write(&led_cdev->trigger_lock);
63
64 up_read(&triggers_list_lock);
65 goto unlock;
66 }
67 }
68 /* we come here only if buf matches no trigger */
69 ret = -EINVAL;
70 up_read(&triggers_list_lock);
71
72 unlock:
73 mutex_unlock(&led_cdev->led_access);
74 return ret;
75 }
76 EXPORT_SYMBOL_GPL(led_trigger_write);
77
78 __printf(3, 4)
led_trigger_snprintf(char * buf,ssize_t size,const char * fmt,...)79 static 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, 0, fmt, args);
87 else
88 i = vscnprintf(buf, size, fmt, args);
89 va_end(args);
90
91 return i;
92 }
93
led_trigger_format(char * buf,size_t size,struct led_classdev * led_cdev)94 static 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, "%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 + len, size - len,
110 " %s%s%s", hit ? "[" : "",
111 trig->name, hit ? "]" : "");
112 }
113
114 len += led_trigger_snprintf(buf + len, size - len, "\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 */
led_trigger_read(struct file * filp,struct kobject * kobj,struct bin_attribute * attr,char * buf,loff_t pos,size_t count)125 ssize_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(&triggers_list_lock);
135 down_read(&led_cdev->trigger_lock);
136
137 len = led_trigger_format(NULL, 0, led_cdev);
138 data = kvmalloc(len + 1, GFP_KERNEL);
139 if (!data) {
140 up_read(&led_cdev->trigger_lock);
141 up_read(&triggers_list_lock);
142 return -ENOMEM;
143 }
144 len = led_trigger_format(data, len + 1, led_cdev);
145
146 up_read(&led_cdev->trigger_lock);
147 up_read(&triggers_list_lock);
148
149 len = memory_read_from_buffer(buf, count, &pos, data, len);
150
151 kvfree(data);
152
153 return len;
154 }
155 EXPORT_SYMBOL_GPL(led_trigger_read);
156
157 /* Caller must ensure led_cdev->trigger_lock held */
led_trigger_set(struct led_classdev * led_cdev,struct led_trigger * trig)158 int 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, "TRIGGER=%s", name);
170
171 /* Remove any existing trigger */
172 if (led_cdev->trigger) {
173 spin_lock(&led_cdev->trigger->leddev_list_lock);
174 list_del_rcu(&led_cdev->trig_list);
175 spin_unlock(&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(&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(led_cdev->dev, 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, LED_OFF);
190 }
191 if (trig) {
192 spin_lock(&trig->leddev_list_lock);
193 list_add_tail_rcu(&led_cdev->trig_list, &trig->led_cdevs);
194 spin_unlock(&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(led_cdev->dev, 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(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
216 dev_err(led_cdev->dev,
217 "%s: Error sending uevent\n", __func__);
218 kfree(event);
219 }
220
221 return 0;
222
223 err_add_groups:
224
225 if (trig->deactivate)
226 trig->deactivate(led_cdev);
227 err_activate:
228
229 spin_lock(&led_cdev->trigger->leddev_list_lock);
230 list_del_rcu(&led_cdev->trig_list);
231 spin_unlock(&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, LED_OFF);
236 kfree(event);
237
238 return ret;
239 }
240 EXPORT_SYMBOL_GPL(led_trigger_set);
241
led_trigger_remove(struct led_classdev * led_cdev)242 void led_trigger_remove(struct led_classdev *led_cdev)
243 {
244 down_write(&led_cdev->trigger_lock);
245 led_trigger_set(led_cdev, NULL);
246 up_write(&led_cdev->trigger_lock);
247 }
248 EXPORT_SYMBOL_GPL(led_trigger_remove);
249
led_trigger_set_default(struct led_classdev * led_cdev)250 void 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(&triggers_list_lock);
258 down_write(&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(&led_cdev->trigger_lock);
268 up_read(&triggers_list_lock);
269 }
270 EXPORT_SYMBOL_GPL(led_trigger_set_default);
271
272 /* LED Trigger Interface */
273
led_trigger_register(struct led_trigger * trig)274 int led_trigger_register(struct led_trigger *trig)
275 {
276 struct led_classdev *led_cdev;
277 struct led_trigger *_trig;
278
279 spin_lock_init(&trig->leddev_list_lock);
280 INIT_LIST_HEAD(&trig->led_cdevs);
281
282 down_write(&triggers_list_lock);
283 /* Make sure the trigger's name isn't already in use */
284 list_for_each_entry(_trig, &trigger_list, next_trig) {
285 if (!strcmp(_trig->name, trig->name) &&
286 (trig->trigger_type == _trig->trigger_type ||
287 !trig->trigger_type || !_trig->trigger_type)) {
288 up_write(&triggers_list_lock);
289 return -EEXIST;
290 }
291 }
292 /* Add to the list of led triggers */
293 list_add_tail(&trig->next_trig, &trigger_list);
294 up_write(&triggers_list_lock);
295
296 /* Register with any LEDs that have this as a default trigger */
297 down_read(&leds_list_lock);
298 list_for_each_entry(led_cdev, &leds_list, node) {
299 down_write(&led_cdev->trigger_lock);
300 if (!led_cdev->trigger && led_cdev->default_trigger &&
301 !strcmp(led_cdev->default_trigger, trig->name) &&
302 trigger_relevant(led_cdev, trig)) {
303 led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
304 led_trigger_set(led_cdev, trig);
305 }
306 up_write(&led_cdev->trigger_lock);
307 }
308 up_read(&leds_list_lock);
309
310 return 0;
311 }
312 EXPORT_SYMBOL_GPL(led_trigger_register);
313
led_trigger_unregister(struct led_trigger * trig)314 void led_trigger_unregister(struct led_trigger *trig)
315 {
316 struct led_classdev *led_cdev;
317
318 if (list_empty_careful(&trig->next_trig))
319 return;
320
321 /* Remove from the list of led triggers */
322 down_write(&triggers_list_lock);
323 list_del_init(&trig->next_trig);
324 up_write(&triggers_list_lock);
325
326 /* Remove anyone actively using this trigger */
327 down_read(&leds_list_lock);
328 list_for_each_entry(led_cdev, &leds_list, node) {
329 down_write(&led_cdev->trigger_lock);
330 if (led_cdev->trigger == trig)
331 led_trigger_set(led_cdev, NULL);
332 up_write(&led_cdev->trigger_lock);
333 }
334 up_read(&leds_list_lock);
335 }
336 EXPORT_SYMBOL_GPL(led_trigger_unregister);
337
devm_led_trigger_release(struct device * dev,void * res)338 static void devm_led_trigger_release(struct device *dev, void *res)
339 {
340 led_trigger_unregister(*(struct led_trigger **)res);
341 }
342
devm_led_trigger_register(struct device * dev,struct led_trigger * trig)343 int devm_led_trigger_register(struct device *dev,
344 struct led_trigger *trig)
345 {
346 struct led_trigger **dr;
347 int rc;
348
349 dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
350 GFP_KERNEL);
351 if (!dr)
352 return -ENOMEM;
353
354 *dr = trig;
355
356 rc = led_trigger_register(trig);
357 if (rc)
358 devres_free(dr);
359 else
360 devres_add(dev, dr);
361
362 return rc;
363 }
364 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
365
366 /* Simple LED Trigger Interface */
367
led_trigger_event(struct led_trigger * trig,enum led_brightness brightness)368 void led_trigger_event(struct led_trigger *trig,
369 enum led_brightness brightness)
370 {
371 struct led_classdev *led_cdev;
372
373 if (!trig)
374 return;
375
376 rcu_read_lock();
377 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
378 led_set_brightness(led_cdev, brightness);
379 rcu_read_unlock();
380 }
381 EXPORT_SYMBOL_GPL(led_trigger_event);
382
led_trigger_blink_setup(struct led_trigger * trig,unsigned long delay_on,unsigned long delay_off,int oneshot,int invert)383 static void led_trigger_blink_setup(struct led_trigger *trig,
384 unsigned long delay_on,
385 unsigned long delay_off,
386 int oneshot,
387 int invert)
388 {
389 struct led_classdev *led_cdev;
390
391 if (!trig)
392 return;
393
394 rcu_read_lock();
395 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
396 if (oneshot)
397 led_blink_set_oneshot(led_cdev, &delay_on, &delay_off,
398 invert);
399 else
400 led_blink_set_nosleep(led_cdev, delay_on, delay_off);
401 }
402 rcu_read_unlock();
403 }
404
led_trigger_blink(struct led_trigger * trig,unsigned long delay_on,unsigned long delay_off)405 void led_trigger_blink(struct led_trigger *trig,
406 unsigned long delay_on,
407 unsigned long delay_off)
408 {
409 led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
410 }
411 EXPORT_SYMBOL_GPL(led_trigger_blink);
412
led_trigger_blink_oneshot(struct led_trigger * trig,unsigned long delay_on,unsigned long delay_off,int invert)413 void led_trigger_blink_oneshot(struct led_trigger *trig,
414 unsigned long delay_on,
415 unsigned long delay_off,
416 int invert)
417 {
418 led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
419 }
420 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
421
led_trigger_register_simple(const char * name,struct led_trigger ** tp)422 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
423 {
424 struct led_trigger *trig;
425 int err;
426
427 trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
428
429 if (trig) {
430 trig->name = name;
431 err = led_trigger_register(trig);
432 if (err < 0) {
433 kfree(trig);
434 trig = NULL;
435 pr_warn("LED trigger %s failed to register (%d)\n",
436 name, err);
437 }
438 } else {
439 pr_warn("LED trigger %s failed to register (no memory)\n",
440 name);
441 }
442 *tp = trig;
443 }
444 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
445
led_trigger_unregister_simple(struct led_trigger * trig)446 void led_trigger_unregister_simple(struct led_trigger *trig)
447 {
448 if (trig)
449 led_trigger_unregister(trig);
450 kfree(trig);
451 }
452 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
453