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 		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_set_brightness(led_cdev, LED_OFF);
189 	}
190 	if (trig) {
191 		spin_lock(&trig->leddev_list_lock);
192 		list_add_tail_rcu(&led_cdev->trig_list, &trig->led_cdevs);
193 		spin_unlock(&trig->leddev_list_lock);
194 		led_cdev->trigger = trig;
195 
196 		if (trig->activate)
197 			ret = trig->activate(led_cdev);
198 		else
199 			ret = 0;
200 
201 		if (ret)
202 			goto err_activate;
203 
204 		ret = device_add_groups(led_cdev->dev, trig->groups);
205 		if (ret) {
206 			dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
207 			goto err_add_groups;
208 		}
209 	}
210 
211 	if (event) {
212 		envp[0] = event;
213 		envp[1] = NULL;
214 		if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
215 			dev_err(led_cdev->dev,
216 				"%s: Error sending uevent\n", __func__);
217 		kfree(event);
218 	}
219 
220 	return 0;
221 
222 err_add_groups:
223 
224 	if (trig->deactivate)
225 		trig->deactivate(led_cdev);
226 err_activate:
227 
228 	spin_lock(&led_cdev->trigger->leddev_list_lock);
229 	list_del_rcu(&led_cdev->trig_list);
230 	spin_unlock(&led_cdev->trigger->leddev_list_lock);
231 	synchronize_rcu();
232 	led_cdev->trigger = NULL;
233 	led_cdev->trigger_data = NULL;
234 	led_set_brightness(led_cdev, LED_OFF);
235 	kfree(event);
236 
237 	return ret;
238 }
239 EXPORT_SYMBOL_GPL(led_trigger_set);
240 
led_trigger_remove(struct led_classdev * led_cdev)241 void led_trigger_remove(struct led_classdev *led_cdev)
242 {
243 	down_write(&led_cdev->trigger_lock);
244 	led_trigger_set(led_cdev, NULL);
245 	up_write(&led_cdev->trigger_lock);
246 }
247 EXPORT_SYMBOL_GPL(led_trigger_remove);
248 
led_trigger_set_default(struct led_classdev * led_cdev)249 void led_trigger_set_default(struct led_classdev *led_cdev)
250 {
251 	struct led_trigger *trig;
252 
253 	if (!led_cdev->default_trigger)
254 		return;
255 
256 	down_read(&triggers_list_lock);
257 	down_write(&led_cdev->trigger_lock);
258 	list_for_each_entry(trig, &trigger_list, next_trig) {
259 		if (!strcmp(led_cdev->default_trigger, trig->name) &&
260 		    trigger_relevant(led_cdev, trig)) {
261 			led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
262 			led_trigger_set(led_cdev, trig);
263 			break;
264 		}
265 	}
266 	up_write(&led_cdev->trigger_lock);
267 	up_read(&triggers_list_lock);
268 }
269 EXPORT_SYMBOL_GPL(led_trigger_set_default);
270 
led_trigger_rename_static(const char * name,struct led_trigger * trig)271 void led_trigger_rename_static(const char *name, struct led_trigger *trig)
272 {
273 	/* new name must be on a temporary string to prevent races */
274 	BUG_ON(name == trig->name);
275 
276 	down_write(&triggers_list_lock);
277 	/* this assumes that trig->name was originaly allocated to
278 	 * non constant storage */
279 	strcpy((char *)trig->name, name);
280 	up_write(&triggers_list_lock);
281 }
282 EXPORT_SYMBOL_GPL(led_trigger_rename_static);
283 
284 /* LED Trigger Interface */
285 
led_trigger_register(struct led_trigger * trig)286 int led_trigger_register(struct led_trigger *trig)
287 {
288 	struct led_classdev *led_cdev;
289 	struct led_trigger *_trig;
290 
291 	spin_lock_init(&trig->leddev_list_lock);
292 	INIT_LIST_HEAD(&trig->led_cdevs);
293 
294 	down_write(&triggers_list_lock);
295 	/* Make sure the trigger's name isn't already in use */
296 	list_for_each_entry(_trig, &trigger_list, next_trig) {
297 		if (!strcmp(_trig->name, trig->name) &&
298 		    (trig->trigger_type == _trig->trigger_type ||
299 		     !trig->trigger_type || !_trig->trigger_type)) {
300 			up_write(&triggers_list_lock);
301 			return -EEXIST;
302 		}
303 	}
304 	/* Add to the list of led triggers */
305 	list_add_tail(&trig->next_trig, &trigger_list);
306 	up_write(&triggers_list_lock);
307 
308 	/* Register with any LEDs that have this as a default trigger */
309 	down_read(&leds_list_lock);
310 	list_for_each_entry(led_cdev, &leds_list, node) {
311 		down_write(&led_cdev->trigger_lock);
312 		if (!led_cdev->trigger && led_cdev->default_trigger &&
313 		    !strcmp(led_cdev->default_trigger, trig->name) &&
314 		    trigger_relevant(led_cdev, trig)) {
315 			led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
316 			led_trigger_set(led_cdev, trig);
317 		}
318 		up_write(&led_cdev->trigger_lock);
319 	}
320 	up_read(&leds_list_lock);
321 
322 	return 0;
323 }
324 EXPORT_SYMBOL_GPL(led_trigger_register);
325 
led_trigger_unregister(struct led_trigger * trig)326 void led_trigger_unregister(struct led_trigger *trig)
327 {
328 	struct led_classdev *led_cdev;
329 
330 	if (list_empty_careful(&trig->next_trig))
331 		return;
332 
333 	/* Remove from the list of led triggers */
334 	down_write(&triggers_list_lock);
335 	list_del_init(&trig->next_trig);
336 	up_write(&triggers_list_lock);
337 
338 	/* Remove anyone actively using this trigger */
339 	down_read(&leds_list_lock);
340 	list_for_each_entry(led_cdev, &leds_list, node) {
341 		down_write(&led_cdev->trigger_lock);
342 		if (led_cdev->trigger == trig)
343 			led_trigger_set(led_cdev, NULL);
344 		up_write(&led_cdev->trigger_lock);
345 	}
346 	up_read(&leds_list_lock);
347 }
348 EXPORT_SYMBOL_GPL(led_trigger_unregister);
349 
devm_led_trigger_release(struct device * dev,void * res)350 static void devm_led_trigger_release(struct device *dev, void *res)
351 {
352 	led_trigger_unregister(*(struct led_trigger **)res);
353 }
354 
devm_led_trigger_register(struct device * dev,struct led_trigger * trig)355 int devm_led_trigger_register(struct device *dev,
356 			      struct led_trigger *trig)
357 {
358 	struct led_trigger **dr;
359 	int rc;
360 
361 	dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
362 			  GFP_KERNEL);
363 	if (!dr)
364 		return -ENOMEM;
365 
366 	*dr = trig;
367 
368 	rc = led_trigger_register(trig);
369 	if (rc)
370 		devres_free(dr);
371 	else
372 		devres_add(dev, dr);
373 
374 	return rc;
375 }
376 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
377 
378 /* Simple LED Trigger Interface */
379 
led_trigger_event(struct led_trigger * trig,enum led_brightness brightness)380 void led_trigger_event(struct led_trigger *trig,
381 			enum led_brightness brightness)
382 {
383 	struct led_classdev *led_cdev;
384 
385 	if (!trig)
386 		return;
387 
388 	rcu_read_lock();
389 	list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
390 		led_set_brightness(led_cdev, brightness);
391 	rcu_read_unlock();
392 }
393 EXPORT_SYMBOL_GPL(led_trigger_event);
394 
led_trigger_blink_setup(struct led_trigger * trig,unsigned long * delay_on,unsigned long * delay_off,int oneshot,int invert)395 static void led_trigger_blink_setup(struct led_trigger *trig,
396 			     unsigned long *delay_on,
397 			     unsigned long *delay_off,
398 			     int oneshot,
399 			     int invert)
400 {
401 	struct led_classdev *led_cdev;
402 
403 	if (!trig)
404 		return;
405 
406 	rcu_read_lock();
407 	list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) {
408 		if (oneshot)
409 			led_blink_set_oneshot(led_cdev, delay_on, delay_off,
410 					      invert);
411 		else
412 			led_blink_set(led_cdev, delay_on, delay_off);
413 	}
414 	rcu_read_unlock();
415 }
416 
led_trigger_blink(struct led_trigger * trig,unsigned long * delay_on,unsigned long * delay_off)417 void led_trigger_blink(struct led_trigger *trig,
418 		       unsigned long *delay_on,
419 		       unsigned long *delay_off)
420 {
421 	led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
422 }
423 EXPORT_SYMBOL_GPL(led_trigger_blink);
424 
led_trigger_blink_oneshot(struct led_trigger * trig,unsigned long * delay_on,unsigned long * delay_off,int invert)425 void led_trigger_blink_oneshot(struct led_trigger *trig,
426 			       unsigned long *delay_on,
427 			       unsigned long *delay_off,
428 			       int invert)
429 {
430 	led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
431 }
432 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
433 
led_trigger_register_simple(const char * name,struct led_trigger ** tp)434 void led_trigger_register_simple(const char *name, struct led_trigger **tp)
435 {
436 	struct led_trigger *trig;
437 	int err;
438 
439 	trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
440 
441 	if (trig) {
442 		trig->name = name;
443 		err = led_trigger_register(trig);
444 		if (err < 0) {
445 			kfree(trig);
446 			trig = NULL;
447 			pr_warn("LED trigger %s failed to register (%d)\n",
448 				name, err);
449 		}
450 	} else {
451 		pr_warn("LED trigger %s failed to register (no memory)\n",
452 			name);
453 	}
454 	*tp = trig;
455 }
456 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
457 
led_trigger_unregister_simple(struct led_trigger * trig)458 void led_trigger_unregister_simple(struct led_trigger *trig)
459 {
460 	if (trig)
461 		led_trigger_unregister(trig);
462 	kfree(trig);
463 }
464 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
465