led-triggers.c

  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			  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
 77unlock:
 78	mutex_unlock(&led_cdev->led_access);
 79	return ret;
 80}
 81EXPORT_SYMBOL_GPL(led_trigger_write);
 82
 83__printf(3, 4)
 84static 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
 99static 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 */
133ssize_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}
163EXPORT_SYMBOL_GPL(led_trigger_read);
164
165/* Caller must ensure led_cdev->trigger_lock held */
166int 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
244err_add_groups:
245
246	if (trig->deactivate)
247		trig->deactivate(led_cdev);
248err_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}
261EXPORT_SYMBOL_GPL(led_trigger_set);
262
263void 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}
269EXPORT_SYMBOL_GPL(led_trigger_remove);
270
271static 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
284void 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}
314EXPORT_SYMBOL_GPL(led_trigger_set_default);
315
316/* LED Trigger Interface */
317
318int 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}
352EXPORT_SYMBOL_GPL(led_trigger_register);
353
354void 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}
376EXPORT_SYMBOL_GPL(led_trigger_unregister);
377
378static void devm_led_trigger_release(struct device *dev, void *res)
379{
380	led_trigger_unregister(*(struct led_trigger **)res);
381}
382
383int 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}
404EXPORT_SYMBOL_GPL(devm_led_trigger_register);
405
406/* Simple LED Trigger Interface */
407
408void 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}
423EXPORT_SYMBOL_GPL(led_trigger_event);
424
425void 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}
443EXPORT_SYMBOL_GPL(led_mc_trigger_event);
444
445static 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
467void 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}
473EXPORT_SYMBOL_GPL(led_trigger_blink);
474
475void 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}
482EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
483
484void 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}
506EXPORT_SYMBOL_GPL(led_trigger_register_simple);
507
508void led_trigger_unregister_simple(struct led_trigger *trig)
509{
510	if (trig)
511		led_trigger_unregister(trig);
512	kfree(trig);
513}
514EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);