xref: /linux/drivers/leds/led-triggers.c (revision 25489a4f556414445d342951615178368ee45cde)
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 static LIST_HEAD(trigger_list);
27 
28  /* Used by LED Class */
29 
30 static inline bool
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 
36 ssize_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(&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 	if (sysfs_streq(buf, "default")) {
58 		led_trigger_set_default(led_cdev);
59 		goto unlock;
60 	}
61 
62 	down_read(&triggers_list_lock);
63 	list_for_each_entry(trig, &trigger_list, next_trig) {
64 		if (sysfs_streq(buf, trig->name) && trigger_relevant(led_cdev, trig)) {
65 			down_write(&led_cdev->trigger_lock);
66 			led_trigger_set(led_cdev, trig);
67 			up_write(&led_cdev->trigger_lock);
68 
69 			up_read(&triggers_list_lock);
70 			goto unlock;
71 		}
72 	}
73 	/* we come here only if buf matches no trigger */
74 	ret = -EINVAL;
75 	up_read(&triggers_list_lock);
76 
77 unlock:
78 	mutex_unlock(&led_cdev->led_access);
79 	return ret;
80 }
81 EXPORT_SYMBOL_GPL(led_trigger_write);
82 
83 __printf(3, 4)
84 static 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, 0, fmt, args);
92 	else
93 		i = vscnprintf(buf, size, fmt, args);
94 	va_end(args);
95 
96 	return i;
97 }
98 
99 static 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, "%s",
104 				       led_cdev->trigger ? "none" : "[none]");
105 
106 	if (led_cdev->default_trigger)
107 		len += led_trigger_snprintf(buf + len, size - len, " 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 + len, size - len,
118 					    " %s%s%s", hit ? "[" : "",
119 					    trig->name, hit ? "]" : "");
120 	}
121 
122 	len += led_trigger_snprintf(buf + len, size - len, "\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  */
133 ssize_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(&triggers_list_lock);
143 	down_read(&led_cdev->trigger_lock);
144 
145 	len = led_trigger_format(NULL, 0, led_cdev);
146 	data = kvmalloc(len + 1, GFP_KERNEL);
147 	if (!data) {
148 		up_read(&led_cdev->trigger_lock);
149 		up_read(&triggers_list_lock);
150 		return -ENOMEM;
151 	}
152 	len = led_trigger_format(data, len + 1, led_cdev);
153 
154 	up_read(&led_cdev->trigger_lock);
155 	up_read(&triggers_list_lock);
156 
157 	len = memory_read_from_buffer(buf, count, &pos, data, len);
158 
159 	kvfree(data);
160 
161 	return len;
162 }
163 EXPORT_SYMBOL_GPL(led_trigger_read);
164 
165 /* Caller must ensure led_cdev->trigger_lock held */
166 int 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, "TRIGGER=%s", name);
178 
179 	/* Remove any existing trigger */
180 	if (led_cdev->trigger) {
181 		spin_lock(&led_cdev->trigger->leddev_list_lock);
182 		list_del_rcu(&led_cdev->trig_list);
183 		spin_unlock(&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(&led_cdev->set_brightness_work);
189 		led_stop_software_blink(led_cdev);
190 		device_remove_groups(led_cdev->dev, 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, LED_OFF);
198 	}
199 	if (trig) {
200 		spin_lock(&trig->leddev_list_lock);
201 		list_add_tail_rcu(&led_cdev->trig_list, &trig->led_cdevs);
202 		spin_unlock(&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(&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, trig->brightness);
223 		if (ret)
224 			goto err_activate;
225 
226 		ret = device_add_groups(led_cdev->dev, 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(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
237 			dev_err(led_cdev->dev,
238 				"%s: Error sending uevent\n", __func__);
239 		kfree(event);
240 	}
241 
242 	return 0;
243 
244 err_add_groups:
245 
246 	if (trig->deactivate)
247 		trig->deactivate(led_cdev);
248 err_activate:
249 
250 	spin_lock(&led_cdev->trigger->leddev_list_lock);
251 	list_del_rcu(&led_cdev->trig_list);
252 	spin_unlock(&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, LED_OFF);
257 	kfree(event);
258 
259 	return ret;
260 }
261 EXPORT_SYMBOL_GPL(led_trigger_set);
262 
263 void led_trigger_remove(struct led_classdev *led_cdev)
264 {
265 	down_write(&led_cdev->trigger_lock);
266 	led_trigger_set(led_cdev, NULL);
267 	up_write(&led_cdev->trigger_lock);
268 }
269 EXPORT_SYMBOL_GPL(led_trigger_remove);
270 
271 static 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 
284 void 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(&triggers_list_lock);
298 	down_write(&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(&led_cdev->trigger_lock);
305 	up_read(&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 }
314 EXPORT_SYMBOL_GPL(led_trigger_set_default);
315 
316 /* LED Trigger Interface */
317 
318 int 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(&trig->led_cdevs);
325 
326 	down_write(&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(&triggers_list_lock);
333 			return -EEXIST;
334 		}
335 	}
336 	/* Add to the list of led triggers */
337 	list_add_tail(&trig->next_trig, &trigger_list);
338 	up_write(&triggers_list_lock);
339 
340 	/* Register with any LEDs that have this as a default trigger */
341 	down_read(&leds_list_lock);
342 	list_for_each_entry(led_cdev, &leds_list, node) {
343 		down_write(&led_cdev->trigger_lock);
344 		if (!led_cdev->trigger && led_cdev->default_trigger)
345 			led_match_default_trigger(led_cdev, trig);
346 		up_write(&led_cdev->trigger_lock);
347 	}
348 	up_read(&leds_list_lock);
349 
350 	return 0;
351 }
352 EXPORT_SYMBOL_GPL(led_trigger_register);
353 
354 void led_trigger_unregister(struct led_trigger *trig)
355 {
356 	struct led_classdev *led_cdev;
357 
358 	if (list_empty_careful(&trig->next_trig))
359 		return;
360 
361 	/* Remove from the list of led triggers */
362 	down_write(&triggers_list_lock);
363 	list_del_init(&trig->next_trig);
364 	up_write(&triggers_list_lock);
365 
366 	/* Remove anyone actively using this trigger */
367 	down_read(&leds_list_lock);
368 	list_for_each_entry(led_cdev, &leds_list, node) {
369 		down_write(&led_cdev->trigger_lock);
370 		if (led_cdev->trigger == trig)
371 			led_trigger_set(led_cdev, NULL);
372 		up_write(&led_cdev->trigger_lock);
373 	}
374 	up_read(&leds_list_lock);
375 }
376 EXPORT_SYMBOL_GPL(led_trigger_unregister);
377 
378 static void devm_led_trigger_release(struct device *dev, void *res)
379 {
380 	led_trigger_unregister(*(struct led_trigger **)res);
381 }
382 
383 int 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(dr);
399 	else
400 		devres_add(dev, dr);
401 
402 	return rc;
403 }
404 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
405 
406 /* Simple LED Trigger Interface */
407 
408 void 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 }
423 EXPORT_SYMBOL_GPL(led_trigger_event);
424 
425 void 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 }
443 EXPORT_SYMBOL_GPL(led_mc_trigger_event);
444 
445 static 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_off,
460 					      invert);
461 		else
462 			led_blink_set_nosleep(led_cdev, delay_on, delay_off);
463 	}
464 	rcu_read_unlock();
465 }
466 
467 void 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, 0, 0);
472 }
473 EXPORT_SYMBOL_GPL(led_trigger_blink);
474 
475 void 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, 1, invert);
481 }
482 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
483 
484 void 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(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 }
506 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
507 
508 void led_trigger_unregister_simple(struct led_trigger *trig)
509 {
510 	if (trig)
511 		led_trigger_unregister(trig);
512 	kfree(trig);
513 }
514 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
515