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 device_remove_groups(led_cdev->dev, led_cdev->trigger->groups);
183 if (led_cdev->trigger->deactivate)
184 led_cdev->trigger->deactivate(led_cdev);
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 /*
198 * Some activate() calls use led_trigger_event() to initialize
199 * the brightness of the LED for which the trigger is being set.
200 * Ensure the led_cdev is visible on trig->led_cdevs for this.
201 */
202 synchronize_rcu();
203
204 /*
205 * If "set brightness to 0" is pending in workqueue,
206 * we don't want that to be reordered after ->activate()
207 */
208 flush_work(&led_cdev->set_brightness_work);
209
210 ret = 0;
211 if (trig->activate)
212 ret = trig->activate(led_cdev);
213 else
214 led_set_brightness(led_cdev, trig->brightness);
215 if (ret)
216 goto err_activate;
217
218 ret = device_add_groups(led_cdev->dev, trig->groups);
219 if (ret) {
220 dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
221 goto err_add_groups;
222 }
223 }
224
225 if (event) {
226 envp[0] = event;
227 envp[1] = NULL;
228 if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
229 dev_err(led_cdev->dev,
230 "%s: Error sending uevent\n", __func__);
231 kfree(event);
232 }
233
234 return 0;
235
236 err_add_groups:
237
238 if (trig->deactivate)
239 trig->deactivate(led_cdev);
240 err_activate:
241
242 spin_lock(&led_cdev->trigger->leddev_list_lock);
243 list_del_rcu(&led_cdev->trig_list);
244 spin_unlock(&led_cdev->trigger->leddev_list_lock);
245 synchronize_rcu();
246 led_cdev->trigger = NULL;
247 led_cdev->trigger_data = NULL;
248 led_set_brightness(led_cdev, LED_OFF);
249 kfree(event);
250
251 return ret;
252 }
253 EXPORT_SYMBOL_GPL(led_trigger_set);
254
led_trigger_remove(struct led_classdev * led_cdev)255 void led_trigger_remove(struct led_classdev *led_cdev)
256 {
257 down_write(&led_cdev->trigger_lock);
258 led_trigger_set(led_cdev, NULL);
259 up_write(&led_cdev->trigger_lock);
260 }
261 EXPORT_SYMBOL_GPL(led_trigger_remove);
262
led_trigger_set_default(struct led_classdev * led_cdev)263 void led_trigger_set_default(struct led_classdev *led_cdev)
264 {
265 struct led_trigger *trig;
266
267 if (!led_cdev->default_trigger)
268 return;
269
270 down_read(&triggers_list_lock);
271 down_write(&led_cdev->trigger_lock);
272 list_for_each_entry(trig, &trigger_list, next_trig) {
273 if (!strcmp(led_cdev->default_trigger, trig->name) &&
274 trigger_relevant(led_cdev, trig)) {
275 led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
276 led_trigger_set(led_cdev, trig);
277 break;
278 }
279 }
280 up_write(&led_cdev->trigger_lock);
281 up_read(&triggers_list_lock);
282 }
283 EXPORT_SYMBOL_GPL(led_trigger_set_default);
284
285 /* LED Trigger Interface */
286
led_trigger_register(struct led_trigger * trig)287 int 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(&trig->led_cdevs);
294
295 down_write(&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(&triggers_list_lock);
302 return -EEXIST;
303 }
304 }
305 /* Add to the list of led triggers */
306 list_add_tail(&trig->next_trig, &trigger_list);
307 up_write(&triggers_list_lock);
308
309 /* Register with any LEDs that have this as a default trigger */
310 down_read(&leds_list_lock);
311 list_for_each_entry(led_cdev, &leds_list, node) {
312 down_write(&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(&led_cdev->trigger_lock);
320 }
321 up_read(&leds_list_lock);
322
323 return 0;
324 }
325 EXPORT_SYMBOL_GPL(led_trigger_register);
326
led_trigger_unregister(struct led_trigger * trig)327 void led_trigger_unregister(struct led_trigger *trig)
328 {
329 struct led_classdev *led_cdev;
330
331 if (list_empty_careful(&trig->next_trig))
332 return;
333
334 /* Remove from the list of led triggers */
335 down_write(&triggers_list_lock);
336 list_del_init(&trig->next_trig);
337 up_write(&triggers_list_lock);
338
339 /* Remove anyone actively using this trigger */
340 down_read(&leds_list_lock);
341 list_for_each_entry(led_cdev, &leds_list, node) {
342 down_write(&led_cdev->trigger_lock);
343 if (led_cdev->trigger == trig)
344 led_trigger_set(led_cdev, NULL);
345 up_write(&led_cdev->trigger_lock);
346 }
347 up_read(&leds_list_lock);
348 }
349 EXPORT_SYMBOL_GPL(led_trigger_unregister);
350
devm_led_trigger_release(struct device * dev,void * res)351 static void devm_led_trigger_release(struct device *dev, void *res)
352 {
353 led_trigger_unregister(*(struct led_trigger **)res);
354 }
355
devm_led_trigger_register(struct device * dev,struct led_trigger * trig)356 int 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(dr);
372 else
373 devres_add(dev, dr);
374
375 return rc;
376 }
377 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
378
379 /* Simple LED Trigger Interface */
380
led_trigger_event(struct led_trigger * trig,enum led_brightness brightness)381 void 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 trig->brightness = brightness;
390
391 rcu_read_lock();
392 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
393 led_set_brightness(led_cdev, brightness);
394 rcu_read_unlock();
395 }
396 EXPORT_SYMBOL_GPL(led_trigger_event);
397
led_trigger_blink_setup(struct led_trigger * trig,unsigned long delay_on,unsigned long delay_off,int oneshot,int invert)398 static void led_trigger_blink_setup(struct led_trigger *trig,
399 unsigned long delay_on,
400 unsigned long delay_off,
401 int oneshot,
402 int invert)
403 {
404 struct led_classdev *led_cdev;
405
406 if (!trig)
407 return;
408
409 rcu_read_lock();
410 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
411 if (oneshot)
412 led_blink_set_oneshot(led_cdev, &delay_on, &delay_off,
413 invert);
414 else
415 led_blink_set_nosleep(led_cdev, delay_on, delay_off);
416 }
417 rcu_read_unlock();
418 }
419
led_trigger_blink(struct led_trigger * trig,unsigned long delay_on,unsigned long delay_off)420 void led_trigger_blink(struct led_trigger *trig,
421 unsigned long delay_on,
422 unsigned long delay_off)
423 {
424 led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
425 }
426 EXPORT_SYMBOL_GPL(led_trigger_blink);
427
led_trigger_blink_oneshot(struct led_trigger * trig,unsigned long delay_on,unsigned long delay_off,int invert)428 void led_trigger_blink_oneshot(struct led_trigger *trig,
429 unsigned long delay_on,
430 unsigned long delay_off,
431 int invert)
432 {
433 led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
434 }
435 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
436
led_trigger_register_simple(const char * name,struct led_trigger ** tp)437 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
438 {
439 struct led_trigger *trig;
440 int err;
441
442 trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
443
444 if (trig) {
445 trig->name = name;
446 err = led_trigger_register(trig);
447 if (err < 0) {
448 kfree(trig);
449 trig = NULL;
450 pr_warn("LED trigger %s failed to register (%d)\n",
451 name, err);
452 }
453 } else {
454 pr_warn("LED trigger %s failed to register (no memory)\n",
455 name);
456 }
457 *tp = trig;
458 }
459 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
460
led_trigger_unregister_simple(struct led_trigger * trig)461 void led_trigger_unregister_simple(struct led_trigger *trig)
462 {
463 if (trig)
464 led_trigger_unregister(trig);
465 kfree(trig);
466 }
467 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
468