Merge tag 'keys-cve-2020-26541-v3' of git://git.kernel.org/pub/scm/linux/kernel/git...
[linux-2.6-microblaze.git] / drivers / leds / 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  */
25 static DECLARE_RWSEM(triggers_list_lock);
26 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                           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)
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
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  */
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 */
158 int 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                 if (led_cdev->trigger->deactivate)
181                         led_cdev->trigger->deactivate(led_cdev);
182                 device_remove_groups(led_cdev->dev, led_cdev->trigger->groups);
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
220 err_add_groups:
221
222         if (trig->deactivate)
223                 trig->deactivate(led_cdev);
224 err_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 }
236 EXPORT_SYMBOL_GPL(led_trigger_set);
237
238 void 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 }
244 EXPORT_SYMBOL_GPL(led_trigger_remove);
245
246 void 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 }
266 EXPORT_SYMBOL_GPL(led_trigger_set_default);
267
268 void 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 }
279 EXPORT_SYMBOL_GPL(led_trigger_rename_static);
280
281 /* LED Trigger Interface */
282
283 int 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 }
321 EXPORT_SYMBOL_GPL(led_trigger_register);
322
323 void 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 }
345 EXPORT_SYMBOL_GPL(led_trigger_unregister);
346
347 static void devm_led_trigger_release(struct device *dev, void *res)
348 {
349         led_trigger_unregister(*(struct led_trigger **)res);
350 }
351
352 int 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 }
373 EXPORT_SYMBOL_GPL(devm_led_trigger_register);
374
375 /* Simple LED Trigger Interface */
376
377 void 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 }
391 EXPORT_SYMBOL_GPL(led_trigger_event);
392
393 static 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
416 void 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 }
422 EXPORT_SYMBOL_GPL(led_trigger_blink);
423
424 void 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 }
431 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
432
433 void 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 }
455 EXPORT_SYMBOL_GPL(led_trigger_register_simple);
456
457 void led_trigger_unregister_simple(struct led_trigger *trig)
458 {
459         if (trig)
460                 led_trigger_unregister(trig);
461         kfree(trig);
462 }
463 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);