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);
26LIST_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(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
72unlock:
73	mutex_unlock(&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, 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, "%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 */
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(&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}
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	unsigned long flags;
161	char *event = NULL;
162	char *envp[2];
163	const char *name;
164	int ret;
165
166	if (!led_cdev->trigger && !trig)
167		return 0;
168
169	name = trig ? trig->name : "none";
170	event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
171
172	/* Remove any existing trigger */
173	if (led_cdev->trigger) {
174		write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
175		list_del(&led_cdev->trig_list);
176		write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
177			flags);
178		cancel_work_sync(&led_cdev->set_brightness_work);
179		led_stop_software_blink(led_cdev);
180		device_remove_groups(led_cdev->dev, led_cdev->trigger->groups);
181		if (led_cdev->trigger->deactivate)
182			led_cdev->trigger->deactivate(led_cdev);
183		led_cdev->trigger = NULL;
184		led_cdev->trigger_data = NULL;
185		led_cdev->activated = false;
186		led_set_brightness(led_cdev, LED_OFF);
187	}
188	if (trig) {
189		write_lock_irqsave(&trig->leddev_list_lock, flags);
190		list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
191		write_unlock_irqrestore(&trig->leddev_list_lock, flags);
192		led_cdev->trigger = trig;
193
194		if (trig->activate)
195			ret = trig->activate(led_cdev);
196		else
197			ret = 0;
198
199		if (ret)
200			goto err_activate;
201
202		ret = device_add_groups(led_cdev->dev, trig->groups);
203		if (ret) {
204			dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
205			goto err_add_groups;
206		}
207	}
208
209	if (event) {
210		envp[0] = event;
211		envp[1] = NULL;
212		if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
213			dev_err(led_cdev->dev,
214				"%s: Error sending uevent\n", __func__);
215		kfree(event);
216	}
217
218	return 0;
219
220err_add_groups:
221
222	if (trig->deactivate)
223		trig->deactivate(led_cdev);
224err_activate:
225
226	write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
227	list_del(&led_cdev->trig_list);
228	write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock, flags);
229	led_cdev->trigger = NULL;
230	led_cdev->trigger_data = NULL;
231	led_set_brightness(led_cdev, LED_OFF);
232	kfree(event);
233
234	return ret;
235}
236EXPORT_SYMBOL_GPL(led_trigger_set);
237
238void led_trigger_remove(struct led_classdev *led_cdev)
239{
240	down_write(&led_cdev->trigger_lock);
241	led_trigger_set(led_cdev, NULL);
242	up_write(&led_cdev->trigger_lock);
243}
244EXPORT_SYMBOL_GPL(led_trigger_remove);
245
246void led_trigger_set_default(struct led_classdev *led_cdev)
247{
248	struct led_trigger *trig;
249
250	if (!led_cdev->default_trigger)
251		return;
252
253	down_read(&triggers_list_lock);
254	down_write(&led_cdev->trigger_lock);
255	list_for_each_entry(trig, &trigger_list, next_trig) {
256		if (!strcmp(led_cdev->default_trigger, trig->name) &&
257		    trigger_relevant(led_cdev, trig)) {
258			led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
259			led_trigger_set(led_cdev, trig);
260			break;
261		}
262	}
263	up_write(&led_cdev->trigger_lock);
264	up_read(&triggers_list_lock);
265}
266EXPORT_SYMBOL_GPL(led_trigger_set_default);
267
268void led_trigger_rename_static(const char *name, struct led_trigger *trig)
269{
270	/* new name must be on a temporary string to prevent races */
271	BUG_ON(name == trig->name);
272
273	down_write(&triggers_list_lock);
274	/* this assumes that trig->name was originaly allocated to
275	 * non constant storage */
276	strcpy((char *)trig->name, name);
277	up_write(&triggers_list_lock);
278}
279EXPORT_SYMBOL_GPL(led_trigger_rename_static);
280
281/* LED Trigger Interface */
282
283int led_trigger_register(struct led_trigger *trig)
284{
285	struct led_classdev *led_cdev;
286	struct led_trigger *_trig;
287
288	rwlock_init(&trig->leddev_list_lock);
289	INIT_LIST_HEAD(&trig->led_cdevs);
290
291	down_write(&triggers_list_lock);
292	/* Make sure the trigger's name isn't already in use */
293	list_for_each_entry(_trig, &trigger_list, next_trig) {
294		if (!strcmp(_trig->name, trig->name) &&
295		    (trig->trigger_type == _trig->trigger_type ||
296		     !trig->trigger_type || !_trig->trigger_type)) {
297			up_write(&triggers_list_lock);
298			return -EEXIST;
299		}
300	}
301	/* Add to the list of led triggers */
302	list_add_tail(&trig->next_trig, &trigger_list);
303	up_write(&triggers_list_lock);
304
305	/* Register with any LEDs that have this as a default trigger */
306	down_read(&leds_list_lock);
307	list_for_each_entry(led_cdev, &leds_list, node) {
308		down_write(&led_cdev->trigger_lock);
309		if (!led_cdev->trigger && led_cdev->default_trigger &&
310		    !strcmp(led_cdev->default_trigger, trig->name) &&
311		    trigger_relevant(led_cdev, trig)) {
312			led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
313			led_trigger_set(led_cdev, trig);
314		}
315		up_write(&led_cdev->trigger_lock);
316	}
317	up_read(&leds_list_lock);
318
319	return 0;
320}
321EXPORT_SYMBOL_GPL(led_trigger_register);
322
323void led_trigger_unregister(struct led_trigger *trig)
324{
325	struct led_classdev *led_cdev;
326
327	if (list_empty_careful(&trig->next_trig))
328		return;
329
330	/* Remove from the list of led triggers */
331	down_write(&triggers_list_lock);
332	list_del_init(&trig->next_trig);
333	up_write(&triggers_list_lock);
334
335	/* Remove anyone actively using this trigger */
336	down_read(&leds_list_lock);
337	list_for_each_entry(led_cdev, &leds_list, node) {
338		down_write(&led_cdev->trigger_lock);
339		if (led_cdev->trigger == trig)
340			led_trigger_set(led_cdev, NULL);
341		up_write(&led_cdev->trigger_lock);
342	}
343	up_read(&leds_list_lock);
344}
345EXPORT_SYMBOL_GPL(led_trigger_unregister);
346
347static void devm_led_trigger_release(struct device *dev, void *res)
348{
349	led_trigger_unregister(*(struct led_trigger **)res);
350}
351
352int devm_led_trigger_register(struct device *dev,
353			      struct led_trigger *trig)
354{
355	struct led_trigger **dr;
356	int rc;
357
358	dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
359			  GFP_KERNEL);
360	if (!dr)
361		return -ENOMEM;
362
363	*dr = trig;
364
365	rc = led_trigger_register(trig);
366	if (rc)
367		devres_free(dr);
368	else
369		devres_add(dev, dr);
370
371	return rc;
372}
373EXPORT_SYMBOL_GPL(devm_led_trigger_register);
374
375/* Simple LED Trigger Interface */
376
377void led_trigger_event(struct led_trigger *trig,
378			enum led_brightness brightness)
379{
380	struct led_classdev *led_cdev;
381	unsigned long flags;
382
383	if (!trig)
384		return;
385
386	read_lock_irqsave(&trig->leddev_list_lock, flags);
387	list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
388		led_set_brightness(led_cdev, brightness);
389	read_unlock_irqrestore(&trig->leddev_list_lock, flags);
390}
391EXPORT_SYMBOL_GPL(led_trigger_event);
392
393static void led_trigger_blink_setup(struct led_trigger *trig,
394			     unsigned long *delay_on,
395			     unsigned long *delay_off,
396			     int oneshot,
397			     int invert)
398{
399	struct led_classdev *led_cdev;
400	unsigned long flags;
401
402	if (!trig)
403		return;
404
405	read_lock_irqsave(&trig->leddev_list_lock, flags);
406	list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
407		if (oneshot)
408			led_blink_set_oneshot(led_cdev, delay_on, delay_off,
409					      invert);
410		else
411			led_blink_set(led_cdev, delay_on, delay_off);
412	}
413	read_unlock_irqrestore(&trig->leddev_list_lock, flags);
414}
415
416void led_trigger_blink(struct led_trigger *trig,
417		       unsigned long *delay_on,
418		       unsigned long *delay_off)
419{
420	led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
421}
422EXPORT_SYMBOL_GPL(led_trigger_blink);
423
424void led_trigger_blink_oneshot(struct led_trigger *trig,
425			       unsigned long *delay_on,
426			       unsigned long *delay_off,
427			       int invert)
428{
429	led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
430}
431EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
432
433void led_trigger_register_simple(const char *name, struct led_trigger **tp)
434{
435	struct led_trigger *trig;
436	int err;
437
438	trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
439
440	if (trig) {
441		trig->name = name;
442		err = led_trigger_register(trig);
443		if (err < 0) {
444			kfree(trig);
445			trig = NULL;
446			pr_warn("LED trigger %s failed to register (%d)\n",
447				name, err);
448		}
449	} else {
450		pr_warn("LED trigger %s failed to register (no memory)\n",
451			name);
452	}
453	*tp = trig;
454}
455EXPORT_SYMBOL_GPL(led_trigger_register_simple);
456
457void led_trigger_unregister_simple(struct led_trigger *trig)
458{
459	if (trig)
460		led_trigger_unregister(trig);
461	kfree(trig);
462}
463EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
464