drivers/leds/trigger/ledtrig-pattern.c

   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
  17 #define MAX_PATTERNS            1024
  18 /*
  19  * When doing gradual dimming, the led brightness will be updated
  20  * every 50 milliseconds.
  21  */
  22 #define UPDATE_INTERVAL         50
  23
  24 struct pattern_trig_data {
  25         struct led_classdev *led_cdev;
  26         struct led_pattern patterns[MAX_PATTERNS];
  27         struct led_pattern *curr;
  28         struct led_pattern *next;
  29         struct mutex lock;
  30         u32 npatterns;
  31         int repeat;
  32         int last_repeat;
  33         int delta_t;
  34         bool is_indefinite;
  35         bool is_hw_pattern;
  36         struct timer_list timer;
  37 };
  38
  39 static void pattern_trig_update_patterns(struct pattern_trig_data *data)
  40 {
  41         data->curr = data->next;
  42         if (!data->is_indefinite && data->curr == data->patterns)
  43                 data->repeat--;
  44
  45         if (data->next == data->patterns + data->npatterns - 1)
  46                 data->next = data->patterns;
  47         else
  48                 data->next++;
  49
  50         data->delta_t = 0;
  51 }
  52
  53 static int pattern_trig_compute_brightness(struct pattern_trig_data *data)
  54 {
  55         int step_brightness;
  56
  57         /*
  58          * If current tuple's duration is less than the dimming interval,
  59          * we should treat it as a step change of brightness instead of
  60          * doing gradual dimming.
  61          */
  62         if (data->delta_t == 0 || data->curr->delta_t < UPDATE_INTERVAL)
  63                 return data->curr->brightness;
  64
  65         step_brightness = abs(data->next->brightness - data->curr->brightness);
  66         step_brightness = data->delta_t * step_brightness / data->curr->delta_t;
  67
  68         if (data->next->brightness > data->curr->brightness)
  69                 return data->curr->brightness + step_brightness;
  70         else
  71                 return data->curr->brightness - step_brightness;
  72 }
  73
  74 static void pattern_trig_timer_function(struct timer_list *t)
  75 {
  76         struct pattern_trig_data *data = from_timer(data, t, timer);
  77
  78         for (;;) {
  79                 if (!data->is_indefinite && !data->repeat)
  80                         break;
  81
  82                 if (data->curr->brightness == data->next->brightness) {
  83                         /* Step change of brightness */
  84                         led_set_brightness(data->led_cdev,
  85                                            data->curr->brightness);
  86                         mod_timer(&data->timer,
  87                                   jiffies + msecs_to_jiffies(data->curr->delta_t));
  88                         if (!data->next->delta_t) {
  89                                 /* Skip the tuple with zero duration */
  90                                 pattern_trig_update_patterns(data);
  91                         }
  92                         /* Select next tuple */
  93                         pattern_trig_update_patterns(data);
  94                 } else {
  95                         /* Gradual dimming */
  96
  97                         /*
  98                          * If the accumulation time is larger than current
  99                          * tuple's duration, we should go next one and re-check
 100                          * if we repeated done.
 101                          */
 102                         if (data->delta_t > data->curr->delta_t) {
 103                                 pattern_trig_update_patterns(data);
 104                                 continue;
 105                         }
 106
 107                         led_set_brightness(data->led_cdev,
 108                                            pattern_trig_compute_brightness(data));
 109                         mod_timer(&data->timer,
 110                                   jiffies + msecs_to_jiffies(UPDATE_INTERVAL));
 111
 112                         /* Accumulate the gradual dimming time */
 113                         data->delta_t += UPDATE_INTERVAL;
 114                 }
 115
 116                 break;
 117         }
 118 }
 119
 120 static int pattern_trig_start_pattern(struct led_classdev *led_cdev)
 121 {
 122         struct pattern_trig_data *data = led_cdev->trigger_data;
 123
 124         if (!data->npatterns)
 125                 return 0;
 126
 127         if (data->is_hw_pattern) {
 128                 return led_cdev->pattern_set(led_cdev, data->patterns,
 129                                              data->npatterns, data->repeat);
 130         }
 131
 132         /* At least 2 tuples for software pattern. */
 133         if (data->npatterns < 2)
 134                 return -EINVAL;
 135
 136         data->delta_t = 0;
 137         data->curr = data->patterns;
 138         data->next = data->patterns + 1;
 139         data->timer.expires = jiffies;
 140         add_timer(&data->timer);
 141
 142         return 0;
 143 }
 144
 145 static ssize_t repeat_show(struct device *dev, struct device_attribute *attr,
 146                            char *buf)
 147 {
 148         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 149         struct pattern_trig_data *data = led_cdev->trigger_data;
 150         int repeat;
 151
 152         mutex_lock(&data->lock);
 153
 154         repeat = data->last_repeat;
 155
 156         mutex_unlock(&data->lock);
 157
 158         return scnprintf(buf, PAGE_SIZE, "%d\n", repeat);
 159 }
 160
 161 static ssize_t repeat_store(struct device *dev, struct device_attribute *attr,
 162                             const char *buf, size_t count)
 163 {
 164         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 165         struct pattern_trig_data *data = led_cdev->trigger_data;
 166         int err, res;
 167
 168         err = kstrtos32(buf, 10, &res);
 169         if (err)
 170                 return err;
 171
 172         /* Number 0 and negative numbers except -1 are invalid. */
 173         if (res < -1 || res == 0)
 174                 return -EINVAL;
 175
 176         mutex_lock(&data->lock);
 177
 178         del_timer_sync(&data->timer);
 179
 180         if (data->is_hw_pattern)
 181                 led_cdev->pattern_clear(led_cdev);
 182
 183         data->last_repeat = data->repeat = res;
 184         /* -1 means repeat indefinitely */
 185         if (data->repeat == -1)
 186                 data->is_indefinite = true;
 187         else
 188                 data->is_indefinite = false;
 189
 190         err = pattern_trig_start_pattern(led_cdev);
 191
 192         mutex_unlock(&data->lock);
 193         return err < 0 ? err : count;
 194 }
 195
 196 static DEVICE_ATTR_RW(repeat);
 197
 198 static ssize_t pattern_trig_show_patterns(struct pattern_trig_data *data,
 199                                           char *buf, bool hw_pattern)
 200 {
 201         ssize_t count = 0;
 202         int i;
 203
 204         mutex_lock(&data->lock);
 205
 206         if (!data->npatterns || (data->is_hw_pattern ^ hw_pattern))
 207                 goto out;
 208
 209         for (i = 0; i < data->npatterns; i++) {
 210                 count += scnprintf(buf + count, PAGE_SIZE - count,
 211                                    "%d %u ",
 212                                    data->patterns[i].brightness,
 213                                    data->patterns[i].delta_t);
 214         }
 215
 216         buf[count - 1] = '\n';
 217
 218 out:
 219         mutex_unlock(&data->lock);
 220         return count;
 221 }
 222
 223 static ssize_t pattern_trig_store_patterns(struct led_classdev *led_cdev,
 224                                            const char *buf, size_t count,
 225                                            bool hw_pattern)
 226 {
 227         struct pattern_trig_data *data = led_cdev->trigger_data;
 228         int ccount, cr, offset = 0, err = 0;
 229
 230         mutex_lock(&data->lock);
 231
 232         del_timer_sync(&data->timer);
 233
 234         if (data->is_hw_pattern)
 235                 led_cdev->pattern_clear(led_cdev);
 236
 237         data->is_hw_pattern = hw_pattern;
 238         data->npatterns = 0;
 239
 240         while (offset < count - 1 && data->npatterns < MAX_PATTERNS) {
 241                 cr = 0;
 242                 ccount = sscanf(buf + offset, "%d %u %n",
 243                                 &data->patterns[data->npatterns].brightness,
 244                                 &data->patterns[data->npatterns].delta_t, &cr);
 245                 if (ccount != 2) {
 246                         data->npatterns = 0;
 247                         err = -EINVAL;
 248                         goto out;
 249                 }
 250
 251                 offset += cr;
 252                 data->npatterns++;
 253         }
 254
 255         err = pattern_trig_start_pattern(led_cdev);
 256         if (err)
 257                 data->npatterns = 0;
 258
 259 out:
 260         mutex_unlock(&data->lock);
 261         return err < 0 ? err : count;
 262 }
 263
 264 static ssize_t pattern_show(struct device *dev, struct device_attribute *attr,
 265                             char *buf)
 266 {
 267         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 268         struct pattern_trig_data *data = led_cdev->trigger_data;
 269
 270         return pattern_trig_show_patterns(data, buf, false);
 271 }
 272
 273 static ssize_t pattern_store(struct device *dev, struct device_attribute *attr,
 274                              const char *buf, size_t count)
 275 {
 276         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 277
 278         return pattern_trig_store_patterns(led_cdev, buf, count, false);
 279 }
 280
 281 static DEVICE_ATTR_RW(pattern);
 282
 283 static ssize_t hw_pattern_show(struct device *dev,
 284                                struct device_attribute *attr, char *buf)
 285 {
 286         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 287         struct pattern_trig_data *data = led_cdev->trigger_data;
 288
 289         return pattern_trig_show_patterns(data, buf, true);
 290 }
 291
 292 static ssize_t hw_pattern_store(struct device *dev,
 293                                 struct device_attribute *attr,
 294                                 const char *buf, size_t count)
 295 {
 296         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 297
 298         return pattern_trig_store_patterns(led_cdev, buf, count, true);
 299 }
 300
 301 static DEVICE_ATTR_RW(hw_pattern);
 302
 303 static umode_t pattern_trig_attrs_mode(struct kobject *kobj,
 304                                        struct attribute *attr, int index)
 305 {
 306         struct device *dev = container_of(kobj, struct device, kobj);
 307         struct led_classdev *led_cdev = dev_get_drvdata(dev);
 308
 309         if (attr == &dev_attr_repeat.attr || attr == &dev_attr_pattern.attr)
 310                 return attr->mode;
 311         else if (attr == &dev_attr_hw_pattern.attr && led_cdev->pattern_set)
 312                 return attr->mode;
 313
 314         return 0;
 315 }
 316
 317 static struct attribute *pattern_trig_attrs[] = {
 318         &dev_attr_pattern.attr,
 319         &dev_attr_hw_pattern.attr,
 320         &dev_attr_repeat.attr,
 321         NULL
 322 };
 323
 324 static const struct attribute_group pattern_trig_group = {
 325         .attrs = pattern_trig_attrs,
 326         .is_visible = pattern_trig_attrs_mode,
 327 };
 328
 329 static const struct attribute_group *pattern_trig_groups[] = {
 330         &pattern_trig_group,
 331         NULL,
 332 };
 333
 334 static int pattern_trig_activate(struct led_classdev *led_cdev)
 335 {
 336         struct pattern_trig_data *data;
 337
 338         data = kzalloc(sizeof(*data), GFP_KERNEL);
 339         if (!data)
 340                 return -ENOMEM;
 341
 342         if (!!led_cdev->pattern_set ^ !!led_cdev->pattern_clear) {
 343                 dev_warn(led_cdev->dev,
 344                          "Hardware pattern ops validation failed\n");
 345                 led_cdev->pattern_set = NULL;
 346                 led_cdev->pattern_clear = NULL;
 347         }
 348
 349         data->is_indefinite = true;
 350         data->last_repeat = -1;
 351         mutex_init(&data->lock);
 352         data->led_cdev = led_cdev;
 353         led_set_trigger_data(led_cdev, data);
 354         timer_setup(&data->timer, pattern_trig_timer_function, 0);
 355         led_cdev->activated = true;
 356
 357         return 0;
 358 }
 359
 360 static void pattern_trig_deactivate(struct led_classdev *led_cdev)
 361 {
 362         struct pattern_trig_data *data = led_cdev->trigger_data;
 363
 364         if (!led_cdev->activated)
 365                 return;
 366
 367         if (led_cdev->pattern_clear)
 368                 led_cdev->pattern_clear(led_cdev);
 369
 370         del_timer_sync(&data->timer);
 371
 372         led_set_brightness(led_cdev, LED_OFF);
 373         kfree(data);
 374         led_cdev->activated = false;
 375 }
 376
 377 static struct led_trigger pattern_led_trigger = {
 378         .name = "pattern",
 379         .activate = pattern_trig_activate,
 380         .deactivate = pattern_trig_deactivate,
 381         .groups = pattern_trig_groups,
 382 };
 383
 384 static int __init pattern_trig_init(void)
 385 {
 386         return led_trigger_register(&pattern_led_trigger);
 387 }
 388
 389 static void __exit pattern_trig_exit(void)
 390 {
 391         led_trigger_unregister(&pattern_led_trigger);
 392 }
 393
 394 module_init(pattern_trig_init);
 395 module_exit(pattern_trig_exit);
 396
 397 MODULE_AUTHOR("Raphael Teysseyre <rteysseyre@gmail.com");
 398 MODULE_AUTHOR("Baolin Wang <baolin.wang@linaro.org");
 399 MODULE_DESCRIPTION("LED Pattern trigger");
 400 MODULE_LICENSE("GPL v2");