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	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
223err_add_groups:
224
225	if (trig->deactivate)
226		trig->deactivate(led_cdev);
227err_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}
240EXPORT_SYMBOL_GPL(led_trigger_set);
241
242void 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}
248EXPORT_SYMBOL_GPL(led_trigger_remove);
249
250void 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}
270EXPORT_SYMBOL_GPL(led_trigger_set_default);
271
272void led_trigger_rename_static(const char *name, struct led_trigger *trig)
273{
274	/* new name must be on a temporary string to prevent races */
275	BUG_ON(name == trig->name);
276
277	down_write(&triggers_list_lock);
278	/* this assumes that trig->name was originaly allocated to
279	 * non constant storage */
280	strcpy((char *)trig->name, name);
281	up_write(&triggers_list_lock);
282}
283EXPORT_SYMBOL_GPL(led_trigger_rename_static);
284
285/* LED Trigger Interface */
286
287int 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}
325EXPORT_SYMBOL_GPL(led_trigger_register);
326
327void 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}
349EXPORT_SYMBOL_GPL(led_trigger_unregister);
350
351static void devm_led_trigger_release(struct device *dev, void *res)
352{
353	led_trigger_unregister(*(struct led_trigger **)res);
354}
355
356int 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}
377EXPORT_SYMBOL_GPL(devm_led_trigger_register);
378
379/* Simple LED Trigger Interface */
380
381void 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	rcu_read_lock();
390	list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
391		led_set_brightness(led_cdev, brightness);
392	rcu_read_unlock();
393}
394EXPORT_SYMBOL_GPL(led_trigger_event);
395
396static void led_trigger_blink_setup(struct led_trigger *trig,
397			     unsigned long delay_on,
398			     unsigned long delay_off,
399			     int oneshot,
400			     int invert)
401{
402	struct led_classdev *led_cdev;
403
404	if (!trig)
405		return;
406
407	rcu_read_lock();
408	list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
409		if (oneshot)
410			led_blink_set_oneshot(led_cdev, &delay_on, &delay_off,
411					      invert);
412		else
413			led_blink_set_nosleep(led_cdev, delay_on, delay_off);
414	}
415	rcu_read_unlock();
416}
417
418void led_trigger_blink(struct led_trigger *trig,
419		       unsigned long delay_on,
420		       unsigned long delay_off)
421{
422	led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
423}
424EXPORT_SYMBOL_GPL(led_trigger_blink);
425
426void led_trigger_blink_oneshot(struct led_trigger *trig,
427			       unsigned long delay_on,
428			       unsigned long delay_off,
429			       int invert)
430{
431	led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
432}
433EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
434
435void led_trigger_register_simple(const char *name, struct led_trigger **tp)
436{
437	struct led_trigger *trig;
438	int err;
439
440	trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
441
442	if (trig) {
443		trig->name = name;
444		err = led_trigger_register(trig);
445		if (err < 0) {
446			kfree(trig);
447			trig = NULL;
448			pr_warn("LED trigger %s failed to register (%d)\n",
449				name, err);
450		}
451	} else {
452		pr_warn("LED trigger %s failed to register (no memory)\n",
453			name);
454	}
455	*tp = trig;
456}
457EXPORT_SYMBOL_GPL(led_trigger_register_simple);
458
459void led_trigger_unregister_simple(struct led_trigger *trig)
460{
461	if (trig)
462		led_trigger_unregister(trig);
463	kfree(trig);
464}
465EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
466