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 int pattern_trig_store_patterns_string(struct pattern_trig_data *data, 224 const char *buf, size_t count) 225 { 226 int ccount, cr, offset = 0; 227 228 while (offset < count - 1 && data->npatterns < MAX_PATTERNS) { 229 cr = 0; 230 ccount = sscanf(buf + offset, "%d %u %n", 231 &data->patterns[data->npatterns].brightness, 232 &data->patterns[data->npatterns].delta_t, &cr); 233 if (ccount != 2) { 234 data->npatterns = 0; 235 return -EINVAL; 236 } 237 238 offset += cr; 239 data->npatterns++; 240 } 241 242 return 0; 243 } 244 245 static int pattern_trig_store_patterns_int(struct pattern_trig_data *data, 246 const u32 *buf, size_t count) 247 { 248 unsigned int i; 249 250 for (i = 0; i < count; i += 2) { 251 data->patterns[data->npatterns].brightness = buf[i]; 252 data->patterns[data->npatterns].delta_t = buf[i + 1]; 253 data->npatterns++; 254 } 255 256 return 0; 257 } 258 259 static ssize_t pattern_trig_store_patterns(struct led_classdev *led_cdev, 260 const char *buf, const u32 *buf_int, 261 size_t count, bool hw_pattern) 262 { 263 struct pattern_trig_data *data = led_cdev->trigger_data; 264 int err = 0; 265 266 mutex_lock(&data->lock); 267 268 del_timer_sync(&data->timer); 269 270 if (data->is_hw_pattern) 271 led_cdev->pattern_clear(led_cdev); 272 273 data->is_hw_pattern = hw_pattern; 274 data->npatterns = 0; 275 276 if (buf) 277 err = pattern_trig_store_patterns_string(data, buf, count); 278 else 279 err = pattern_trig_store_patterns_int(data, buf_int, count); 280 if (err) 281 goto out; 282 283 err = pattern_trig_start_pattern(led_cdev); 284 if (err) 285 data->npatterns = 0; 286 287 out: 288 mutex_unlock(&data->lock); 289 return err < 0 ? err : count; 290 } 291 292 static ssize_t pattern_show(struct device *dev, struct device_attribute *attr, 293 char *buf) 294 { 295 struct led_classdev *led_cdev = dev_get_drvdata(dev); 296 struct pattern_trig_data *data = led_cdev->trigger_data; 297 298 return pattern_trig_show_patterns(data, buf, false); 299 } 300 301 static ssize_t pattern_store(struct device *dev, struct device_attribute *attr, 302 const char *buf, size_t count) 303 { 304 struct led_classdev *led_cdev = dev_get_drvdata(dev); 305 306 return pattern_trig_store_patterns(led_cdev, buf, NULL, count, false); 307 } 308 309 static DEVICE_ATTR_RW(pattern); 310 311 static ssize_t hw_pattern_show(struct device *dev, 312 struct device_attribute *attr, char *buf) 313 { 314 struct led_classdev *led_cdev = dev_get_drvdata(dev); 315 struct pattern_trig_data *data = led_cdev->trigger_data; 316 317 return pattern_trig_show_patterns(data, buf, true); 318 } 319 320 static ssize_t hw_pattern_store(struct device *dev, 321 struct device_attribute *attr, 322 const char *buf, size_t count) 323 { 324 struct led_classdev *led_cdev = dev_get_drvdata(dev); 325 326 return pattern_trig_store_patterns(led_cdev, buf, NULL, count, true); 327 } 328 329 static DEVICE_ATTR_RW(hw_pattern); 330 331 static umode_t pattern_trig_attrs_mode(struct kobject *kobj, 332 struct attribute *attr, int index) 333 { 334 struct device *dev = container_of(kobj, struct device, kobj); 335 struct led_classdev *led_cdev = dev_get_drvdata(dev); 336 337 if (attr == &dev_attr_repeat.attr || attr == &dev_attr_pattern.attr) 338 return attr->mode; 339 else if (attr == &dev_attr_hw_pattern.attr && led_cdev->pattern_set) 340 return attr->mode; 341 342 return 0; 343 } 344 345 static struct attribute *pattern_trig_attrs[] = { 346 &dev_attr_pattern.attr, 347 &dev_attr_hw_pattern.attr, 348 &dev_attr_repeat.attr, 349 NULL 350 }; 351 352 static const struct attribute_group pattern_trig_group = { 353 .attrs = pattern_trig_attrs, 354 .is_visible = pattern_trig_attrs_mode, 355 }; 356 357 static const struct attribute_group *pattern_trig_groups[] = { 358 &pattern_trig_group, 359 NULL, 360 }; 361 362 static void pattern_init(struct led_classdev *led_cdev) 363 { 364 unsigned int size = 0; 365 u32 *pattern; 366 int err; 367 368 pattern = led_get_default_pattern(led_cdev, &size); 369 if (!pattern) 370 return; 371 372 if (size % 2) { 373 dev_warn(led_cdev->dev, "Expected pattern of tuples\n"); 374 goto out; 375 } 376 377 err = pattern_trig_store_patterns(led_cdev, NULL, pattern, size, false); 378 if (err < 0) 379 dev_warn(led_cdev->dev, 380 "Pattern initialization failed with error %d\n", err); 381 382 out: 383 kfree(pattern); 384 } 385 386 static int pattern_trig_activate(struct led_classdev *led_cdev) 387 { 388 struct pattern_trig_data *data; 389 390 data = kzalloc(sizeof(*data), GFP_KERNEL); 391 if (!data) 392 return -ENOMEM; 393 394 if (!!led_cdev->pattern_set ^ !!led_cdev->pattern_clear) { 395 dev_warn(led_cdev->dev, 396 "Hardware pattern ops validation failed\n"); 397 led_cdev->pattern_set = NULL; 398 led_cdev->pattern_clear = NULL; 399 } 400 401 data->is_indefinite = true; 402 data->last_repeat = -1; 403 mutex_init(&data->lock); 404 data->led_cdev = led_cdev; 405 led_set_trigger_data(led_cdev, data); 406 timer_setup(&data->timer, pattern_trig_timer_function, 0); 407 led_cdev->activated = true; 408 409 if (led_cdev->flags & LED_INIT_DEFAULT_TRIGGER) { 410 pattern_init(led_cdev); 411 /* 412 * Mark as initialized even on pattern_init() error because 413 * any consecutive call to it would produce the same error. 414 */ 415 led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER; 416 } 417 418 return 0; 419 } 420 421 static void pattern_trig_deactivate(struct led_classdev *led_cdev) 422 { 423 struct pattern_trig_data *data = led_cdev->trigger_data; 424 425 if (!led_cdev->activated) 426 return; 427 428 if (led_cdev->pattern_clear) 429 led_cdev->pattern_clear(led_cdev); 430 431 del_timer_sync(&data->timer); 432 433 led_set_brightness(led_cdev, LED_OFF); 434 kfree(data); 435 led_cdev->activated = false; 436 } 437 438 static struct led_trigger pattern_led_trigger = { 439 .name = "pattern", 440 .activate = pattern_trig_activate, 441 .deactivate = pattern_trig_deactivate, 442 .groups = pattern_trig_groups, 443 }; 444 445 static int __init pattern_trig_init(void) 446 { 447 return led_trigger_register(&pattern_led_trigger); 448 } 449 450 static void __exit pattern_trig_exit(void) 451 { 452 led_trigger_unregister(&pattern_led_trigger); 453 } 454 455 module_init(pattern_trig_init); 456 module_exit(pattern_trig_exit); 457 458 MODULE_AUTHOR("Raphael Teysseyre <rteysseyre@gmail.com"); 459 MODULE_AUTHOR("Baolin Wang <baolin.wang@linaro.org"); 460 MODULE_DESCRIPTION("LED Pattern trigger"); 461 MODULE_LICENSE("GPL v2"); 462