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1// SPDX-License-Identifier: GPL-2.0
2
3/*
4 * LED pattern trigger
5 *
6 * Idea discussed with Pavel Machek. Raphael Teysseyre implemented
7 * the first version, Baolin Wang simplified and improved the approach.
8 */
9
10#include <linux/kernel.h>
11#include <linux/leds.h>
12#include <linux/module.h>
13#include <linux/mutex.h>
14#include <linux/slab.h>
15#include <linux/timer.h>
16#include <linux/hrtimer.h>
17
18#define MAX_PATTERNS 1024
19/*
20 * When doing gradual dimming, the led brightness will be updated
21 * every 50 milliseconds.
22 */
23#define UPDATE_INTERVAL 50
24
25enum pattern_type {
26 PATTERN_TYPE_SW, /* Use standard timer for software pattern */
27 PATTERN_TYPE_HR, /* Use hrtimer for software pattern */
28 PATTERN_TYPE_HW, /* Hardware pattern */
29};
30
31struct pattern_trig_data {
32 struct led_classdev *led_cdev;
33 struct led_pattern patterns[MAX_PATTERNS];
34 struct led_pattern *curr;
35 struct led_pattern *next;
36 struct mutex lock;
37 u32 npatterns;
38 int repeat;
39 int last_repeat;
40 int delta_t;
41 bool is_indefinite;
42 enum pattern_type type;
43 struct timer_list timer;
44 struct hrtimer hrtimer;
45};
46
47static void pattern_trig_update_patterns(struct pattern_trig_data *data)
48{
49 data->curr = data->next;
50 if (!data->is_indefinite && data->curr == data->patterns)
51 data->repeat--;
52
53 if (data->next == data->patterns + data->npatterns - 1)
54 data->next = data->patterns;
55 else
56 data->next++;
57
58 data->delta_t = 0;
59}
60
61static int pattern_trig_compute_brightness(struct pattern_trig_data *data)
62{
63 int step_brightness;
64
65 /*
66 * If current tuple's duration is less than the dimming interval,
67 * we should treat it as a step change of brightness instead of
68 * doing gradual dimming.
69 */
70 if (data->delta_t == 0 || data->curr->delta_t < UPDATE_INTERVAL)
71 return data->curr->brightness;
72
73 step_brightness = abs(data->next->brightness - data->curr->brightness);
74 step_brightness = data->delta_t * step_brightness / data->curr->delta_t;
75
76 if (data->next->brightness > data->curr->brightness)
77 return data->curr->brightness + step_brightness;
78 else
79 return data->curr->brightness - step_brightness;
80}
81
82static void pattern_trig_timer_start(struct pattern_trig_data *data)
83{
84 if (data->type == PATTERN_TYPE_HR) {
85 hrtimer_start(&data->hrtimer, ns_to_ktime(0), HRTIMER_MODE_REL);
86 } else {
87 data->timer.expires = jiffies;
88 add_timer(&data->timer);
89 }
90}
91
92static void pattern_trig_timer_cancel(struct pattern_trig_data *data)
93{
94 if (data->type == PATTERN_TYPE_HR)
95 hrtimer_cancel(&data->hrtimer);
96 else
97 timer_delete_sync(&data->timer);
98}
99
100static void pattern_trig_timer_restart(struct pattern_trig_data *data,
101 unsigned long interval)
102{
103 if (data->type == PATTERN_TYPE_HR)
104 hrtimer_forward_now(&data->hrtimer, ms_to_ktime(interval));
105 else
106 mod_timer(&data->timer, jiffies + msecs_to_jiffies(interval));
107}
108
109static void pattern_trig_timer_common_function(struct pattern_trig_data *data)
110{
111 for (;;) {
112 if (!data->is_indefinite && !data->repeat)
113 break;
114
115 if (data->curr->brightness == data->next->brightness) {
116 /* Step change of brightness */
117 led_set_brightness(data->led_cdev,
118 data->curr->brightness);
119 pattern_trig_timer_restart(data, data->curr->delta_t);
120 if (!data->next->delta_t) {
121 /* Skip the tuple with zero duration */
122 pattern_trig_update_patterns(data);
123 }
124 /* Select next tuple */
125 pattern_trig_update_patterns(data);
126 } else {
127 /* Gradual dimming */
128
129 /*
130 * If the accumulation time is larger than current
131 * tuple's duration, we should go next one and re-check
132 * if we repeated done.
133 */
134 if (data->delta_t > data->curr->delta_t) {
135 pattern_trig_update_patterns(data);
136 continue;
137 }
138
139 led_set_brightness(data->led_cdev,
140 pattern_trig_compute_brightness(data));
141 pattern_trig_timer_restart(data, UPDATE_INTERVAL);
142
143 /* Accumulate the gradual dimming time */
144 data->delta_t += UPDATE_INTERVAL;
145 }
146
147 break;
148 }
149}
150
151static void pattern_trig_timer_function(struct timer_list *t)
152{
153 struct pattern_trig_data *data = timer_container_of(data, t, timer);
154
155 return pattern_trig_timer_common_function(data);
156}
157
158static enum hrtimer_restart pattern_trig_hrtimer_function(struct hrtimer *t)
159{
160 struct pattern_trig_data *data =
161 container_of(t, struct pattern_trig_data, hrtimer);
162
163 pattern_trig_timer_common_function(data);
164 if (!data->is_indefinite && !data->repeat)
165 return HRTIMER_NORESTART;
166
167 return HRTIMER_RESTART;
168}
169
170static int pattern_trig_start_pattern(struct led_classdev *led_cdev)
171{
172 struct pattern_trig_data *data = led_cdev->trigger_data;
173
174 if (!data->npatterns)
175 return 0;
176
177 if (data->type == PATTERN_TYPE_HW) {
178 return led_cdev->pattern_set(led_cdev, data->patterns,
179 data->npatterns, data->repeat);
180 }
181
182 /* At least 2 tuples for software pattern. */
183 if (data->npatterns < 2)
184 return -EINVAL;
185
186 data->delta_t = 0;
187 data->curr = data->patterns;
188 data->next = data->patterns + 1;
189 pattern_trig_timer_start(data);
190
191 return 0;
192}
193
194static ssize_t repeat_show(struct device *dev, struct device_attribute *attr,
195 char *buf)
196{
197 struct led_classdev *led_cdev = dev_get_drvdata(dev);
198 struct pattern_trig_data *data = led_cdev->trigger_data;
199 int repeat;
200
201 mutex_lock(&data->lock);
202
203 repeat = data->last_repeat;
204
205 mutex_unlock(&data->lock);
206
207 return sysfs_emit(buf, "%d\n", repeat);
208}
209
210static ssize_t repeat_store(struct device *dev, struct device_attribute *attr,
211 const char *buf, size_t count)
212{
213 struct led_classdev *led_cdev = dev_get_drvdata(dev);
214 struct pattern_trig_data *data = led_cdev->trigger_data;
215 int err, res;
216
217 err = kstrtos32(buf, 10, &res);
218 if (err)
219 return err;
220
221 /* Number 0 and negative numbers except -1 are invalid. */
222 if (res < -1 || res == 0)
223 return -EINVAL;
224
225 mutex_lock(&data->lock);
226
227 pattern_trig_timer_cancel(data);
228
229 if (data->type == PATTERN_TYPE_HW)
230 led_cdev->pattern_clear(led_cdev);
231
232 data->last_repeat = data->repeat = res;
233 /* -1 means repeat indefinitely */
234 if (data->repeat == -1)
235 data->is_indefinite = true;
236 else
237 data->is_indefinite = false;
238
239 err = pattern_trig_start_pattern(led_cdev);
240
241 mutex_unlock(&data->lock);
242 return err < 0 ? err : count;
243}
244
245static DEVICE_ATTR_RW(repeat);
246
247static ssize_t pattern_trig_show_patterns(struct pattern_trig_data *data,
248 char *buf, enum pattern_type type)
249{
250 ssize_t count = 0;
251 int i;
252
253 mutex_lock(&data->lock);
254
255 if (!data->npatterns || data->type != type)
256 goto out;
257
258 for (i = 0; i < data->npatterns; i++) {
259 count += scnprintf(buf + count, PAGE_SIZE - count,
260 "%d %u ",
261 data->patterns[i].brightness,
262 data->patterns[i].delta_t);
263 }
264
265 buf[count - 1] = '\n';
266
267out:
268 mutex_unlock(&data->lock);
269 return count;
270}
271
272static int pattern_trig_store_patterns_string(struct pattern_trig_data *data,
273 const char *buf, size_t count)
274{
275 int ccount, cr, offset = 0;
276
277 while (offset < count - 1 && data->npatterns < MAX_PATTERNS) {
278 cr = 0;
279 ccount = sscanf(buf + offset, "%u %u %n",
280 &data->patterns[data->npatterns].brightness,
281 &data->patterns[data->npatterns].delta_t, &cr);
282
283 if (ccount != 2 ||
284 data->patterns[data->npatterns].brightness > data->led_cdev->max_brightness) {
285 data->npatterns = 0;
286 return -EINVAL;
287 }
288
289 offset += cr;
290 data->npatterns++;
291 }
292
293 return 0;
294}
295
296static int pattern_trig_store_patterns_int(struct pattern_trig_data *data,
297 const u32 *buf, size_t count)
298{
299 unsigned int i;
300
301 for (i = 0; i < count; i += 2) {
302 data->patterns[data->npatterns].brightness = buf[i];
303 data->patterns[data->npatterns].delta_t = buf[i + 1];
304 data->npatterns++;
305 }
306
307 return 0;
308}
309
310static ssize_t pattern_trig_store_patterns(struct led_classdev *led_cdev,
311 const char *buf, const u32 *buf_int,
312 size_t count, enum pattern_type type)
313{
314 struct pattern_trig_data *data = led_cdev->trigger_data;
315 int err = 0;
316
317 mutex_lock(&data->lock);
318
319 pattern_trig_timer_cancel(data);
320
321 if (data->type == PATTERN_TYPE_HW)
322 led_cdev->pattern_clear(led_cdev);
323
324 data->type = type;
325 data->npatterns = 0;
326
327 if (buf)
328 err = pattern_trig_store_patterns_string(data, buf, count);
329 else
330 err = pattern_trig_store_patterns_int(data, buf_int, count);
331 if (err)
332 goto out;
333
334 err = pattern_trig_start_pattern(led_cdev);
335 if (err)
336 data->npatterns = 0;
337
338out:
339 mutex_unlock(&data->lock);
340 return err < 0 ? err : count;
341}
342
343static ssize_t pattern_show(struct device *dev, struct device_attribute *attr,
344 char *buf)
345{
346 struct led_classdev *led_cdev = dev_get_drvdata(dev);
347 struct pattern_trig_data *data = led_cdev->trigger_data;
348
349 return pattern_trig_show_patterns(data, buf, PATTERN_TYPE_SW);
350}
351
352static ssize_t pattern_store(struct device *dev, struct device_attribute *attr,
353 const char *buf, size_t count)
354{
355 struct led_classdev *led_cdev = dev_get_drvdata(dev);
356
357 return pattern_trig_store_patterns(led_cdev, buf, NULL, count,
358 PATTERN_TYPE_SW);
359}
360
361static DEVICE_ATTR_RW(pattern);
362
363static ssize_t hw_pattern_show(struct device *dev,
364 struct device_attribute *attr, char *buf)
365{
366 struct led_classdev *led_cdev = dev_get_drvdata(dev);
367 struct pattern_trig_data *data = led_cdev->trigger_data;
368
369 return pattern_trig_show_patterns(data, buf, PATTERN_TYPE_HW);
370}
371
372static ssize_t hw_pattern_store(struct device *dev,
373 struct device_attribute *attr,
374 const char *buf, size_t count)
375{
376 struct led_classdev *led_cdev = dev_get_drvdata(dev);
377
378 return pattern_trig_store_patterns(led_cdev, buf, NULL, count,
379 PATTERN_TYPE_HW);
380}
381
382static DEVICE_ATTR_RW(hw_pattern);
383
384static ssize_t hr_pattern_show(struct device *dev,
385 struct device_attribute *attr, char *buf)
386{
387 struct led_classdev *led_cdev = dev_get_drvdata(dev);
388 struct pattern_trig_data *data = led_cdev->trigger_data;
389
390 return pattern_trig_show_patterns(data, buf, PATTERN_TYPE_HR);
391}
392
393static ssize_t hr_pattern_store(struct device *dev,
394 struct device_attribute *attr,
395 const char *buf, size_t count)
396{
397 struct led_classdev *led_cdev = dev_get_drvdata(dev);
398
399 return pattern_trig_store_patterns(led_cdev, buf, NULL, count,
400 PATTERN_TYPE_HR);
401}
402
403static DEVICE_ATTR_RW(hr_pattern);
404
405static umode_t pattern_trig_attrs_mode(struct kobject *kobj,
406 struct attribute *attr, int index)
407{
408 struct device *dev = kobj_to_dev(kobj);
409 struct led_classdev *led_cdev = dev_get_drvdata(dev);
410
411 if (attr == &dev_attr_repeat.attr || attr == &dev_attr_pattern.attr)
412 return attr->mode;
413 else if (attr == &dev_attr_hr_pattern.attr)
414 return attr->mode;
415 else if (attr == &dev_attr_hw_pattern.attr && led_cdev->pattern_set)
416 return attr->mode;
417
418 return 0;
419}
420
421static struct attribute *pattern_trig_attrs[] = {
422 &dev_attr_pattern.attr,
423 &dev_attr_hw_pattern.attr,
424 &dev_attr_hr_pattern.attr,
425 &dev_attr_repeat.attr,
426 NULL
427};
428
429static const struct attribute_group pattern_trig_group = {
430 .attrs = pattern_trig_attrs,
431 .is_visible = pattern_trig_attrs_mode,
432};
433
434static const struct attribute_group *pattern_trig_groups[] = {
435 &pattern_trig_group,
436 NULL,
437};
438
439static void pattern_init(struct led_classdev *led_cdev)
440{
441 unsigned int size = 0;
442 u32 *pattern;
443 int err;
444
445 pattern = led_get_default_pattern(led_cdev, &size);
446 if (!pattern)
447 return;
448
449 if (size % 2) {
450 dev_warn(led_cdev->dev, "Expected pattern of tuples\n");
451 goto out;
452 }
453
454 err = pattern_trig_store_patterns(led_cdev, NULL, pattern, size,
455 PATTERN_TYPE_SW);
456 if (err < 0)
457 dev_warn(led_cdev->dev,
458 "Pattern initialization failed with error %d\n", err);
459
460out:
461 kfree(pattern);
462}
463
464static int pattern_trig_activate(struct led_classdev *led_cdev)
465{
466 struct pattern_trig_data *data;
467
468 data = kzalloc_obj(*data);
469 if (!data)
470 return -ENOMEM;
471
472 if (!!led_cdev->pattern_set ^ !!led_cdev->pattern_clear) {
473 dev_warn(led_cdev->dev,
474 "Hardware pattern ops validation failed\n");
475 led_cdev->pattern_set = NULL;
476 led_cdev->pattern_clear = NULL;
477 }
478
479 data->type = PATTERN_TYPE_SW;
480 data->is_indefinite = true;
481 data->last_repeat = -1;
482 mutex_init(&data->lock);
483 data->led_cdev = led_cdev;
484 led_set_trigger_data(led_cdev, data);
485 timer_setup(&data->timer, pattern_trig_timer_function, 0);
486 hrtimer_setup(&data->hrtimer, pattern_trig_hrtimer_function, CLOCK_MONOTONIC,
487 HRTIMER_MODE_REL);
488 led_cdev->activated = true;
489
490 if (led_cdev->flags & LED_INIT_DEFAULT_TRIGGER) {
491 pattern_init(led_cdev);
492 /*
493 * Mark as initialized even on pattern_init() error because
494 * any consecutive call to it would produce the same error.
495 */
496 led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER;
497 }
498
499 return 0;
500}
501
502static void pattern_trig_deactivate(struct led_classdev *led_cdev)
503{
504 struct pattern_trig_data *data = led_cdev->trigger_data;
505
506 if (!led_cdev->activated)
507 return;
508
509 if (led_cdev->pattern_clear)
510 led_cdev->pattern_clear(led_cdev);
511
512 timer_shutdown_sync(&data->timer);
513 hrtimer_cancel(&data->hrtimer);
514
515 led_set_brightness(led_cdev, LED_OFF);
516 kfree(data);
517 led_cdev->activated = false;
518}
519
520static struct led_trigger pattern_led_trigger = {
521 .name = "pattern",
522 .activate = pattern_trig_activate,
523 .deactivate = pattern_trig_deactivate,
524 .groups = pattern_trig_groups,
525};
526
527static int __init pattern_trig_init(void)
528{
529 return led_trigger_register(&pattern_led_trigger);
530}
531
532static void __exit pattern_trig_exit(void)
533{
534 led_trigger_unregister(&pattern_led_trigger);
535}
536
537module_init(pattern_trig_init);
538module_exit(pattern_trig_exit);
539
540MODULE_AUTHOR("Raphael Teysseyre <[email protected]>");
541MODULE_AUTHOR("Baolin Wang <[email protected]>");
542MODULE_DESCRIPTION("LED Pattern trigger");
543MODULE_LICENSE("GPL v2");