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 static 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 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 device_remove_groups(led_cdev->dev, led_cdev->trigger->groups); 183 if (led_cdev->trigger->deactivate) 184 led_cdev->trigger->deactivate(led_cdev); 185 led_cdev->trigger = NULL; 186 led_cdev->trigger_data = NULL; 187 led_cdev->activated = false; 188 led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER; 189 led_set_brightness(led_cdev, LED_OFF); 190 } 191 if (trig) { 192 spin_lock(&trig->leddev_list_lock); 193 list_add_tail_rcu(&led_cdev->trig_list, &trig->led_cdevs); 194 spin_unlock(&trig->leddev_list_lock); 195 led_cdev->trigger = trig; 196 197 /* 198 * Some activate() calls use led_trigger_event() to initialize 199 * the brightness of the LED for which the trigger is being set. 200 * Ensure the led_cdev is visible on trig->led_cdevs for this. 201 */ 202 synchronize_rcu(); 203 204 ret = 0; 205 if (trig->activate) 206 ret = trig->activate(led_cdev); 207 else 208 led_set_brightness(led_cdev, trig->brightness); 209 if (ret) 210 goto err_activate; 211 212 ret = device_add_groups(led_cdev->dev, trig->groups); 213 if (ret) { 214 dev_err(led_cdev->dev, "Failed to add trigger attributes\n"); 215 goto err_add_groups; 216 } 217 } 218 219 if (event) { 220 envp[0] = event; 221 envp[1] = NULL; 222 if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp)) 223 dev_err(led_cdev->dev, 224 "%s: Error sending uevent\n", __func__); 225 kfree(event); 226 } 227 228 return 0; 229 230 err_add_groups: 231 232 if (trig->deactivate) 233 trig->deactivate(led_cdev); 234 err_activate: 235 236 spin_lock(&led_cdev->trigger->leddev_list_lock); 237 list_del_rcu(&led_cdev->trig_list); 238 spin_unlock(&led_cdev->trigger->leddev_list_lock); 239 synchronize_rcu(); 240 led_cdev->trigger = NULL; 241 led_cdev->trigger_data = NULL; 242 led_set_brightness(led_cdev, LED_OFF); 243 kfree(event); 244 245 return ret; 246 } 247 EXPORT_SYMBOL_GPL(led_trigger_set); 248 249 void led_trigger_remove(struct led_classdev *led_cdev) 250 { 251 down_write(&led_cdev->trigger_lock); 252 led_trigger_set(led_cdev, NULL); 253 up_write(&led_cdev->trigger_lock); 254 } 255 EXPORT_SYMBOL_GPL(led_trigger_remove); 256 257 static bool led_match_default_trigger(struct led_classdev *led_cdev, 258 struct led_trigger *trig) 259 { 260 if (!strcmp(led_cdev->default_trigger, trig->name) && 261 trigger_relevant(led_cdev, trig)) { 262 led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER; 263 led_trigger_set(led_cdev, trig); 264 return true; 265 } 266 267 return false; 268 } 269 270 void led_trigger_set_default(struct led_classdev *led_cdev) 271 { 272 struct led_trigger *trig; 273 bool found = false; 274 275 if (!led_cdev->default_trigger) 276 return; 277 278 down_read(&triggers_list_lock); 279 down_write(&led_cdev->trigger_lock); 280 list_for_each_entry(trig, &trigger_list, next_trig) { 281 found = led_match_default_trigger(led_cdev, trig); 282 if (found) 283 break; 284 } 285 up_write(&led_cdev->trigger_lock); 286 up_read(&triggers_list_lock); 287 288 /* 289 * If default trigger wasn't found, maybe trigger module isn't loaded yet. 290 * Once loaded it will re-probe with all led_cdev's. 291 */ 292 if (!found) 293 request_module_nowait("ledtrig:%s", led_cdev->default_trigger); 294 } 295 EXPORT_SYMBOL_GPL(led_trigger_set_default); 296 297 /* LED Trigger Interface */ 298 299 int led_trigger_register(struct led_trigger *trig) 300 { 301 struct led_classdev *led_cdev; 302 struct led_trigger *_trig; 303 304 spin_lock_init(&trig->leddev_list_lock); 305 INIT_LIST_HEAD(&trig->led_cdevs); 306 307 down_write(&triggers_list_lock); 308 /* Make sure the trigger's name isn't already in use */ 309 list_for_each_entry(_trig, &trigger_list, next_trig) { 310 if (!strcmp(_trig->name, trig->name) && 311 (trig->trigger_type == _trig->trigger_type || 312 !trig->trigger_type || !_trig->trigger_type)) { 313 up_write(&triggers_list_lock); 314 return -EEXIST; 315 } 316 } 317 /* Add to the list of led triggers */ 318 list_add_tail(&trig->next_trig, &trigger_list); 319 up_write(&triggers_list_lock); 320 321 /* Register with any LEDs that have this as a default trigger */ 322 down_read(&leds_list_lock); 323 list_for_each_entry(led_cdev, &leds_list, node) { 324 down_write(&led_cdev->trigger_lock); 325 if (!led_cdev->trigger && led_cdev->default_trigger) 326 led_match_default_trigger(led_cdev, trig); 327 up_write(&led_cdev->trigger_lock); 328 } 329 up_read(&leds_list_lock); 330 331 return 0; 332 } 333 EXPORT_SYMBOL_GPL(led_trigger_register); 334 335 void led_trigger_unregister(struct led_trigger *trig) 336 { 337 struct led_classdev *led_cdev; 338 339 if (list_empty_careful(&trig->next_trig)) 340 return; 341 342 /* Remove from the list of led triggers */ 343 down_write(&triggers_list_lock); 344 list_del_init(&trig->next_trig); 345 up_write(&triggers_list_lock); 346 347 /* Remove anyone actively using this trigger */ 348 down_read(&leds_list_lock); 349 list_for_each_entry(led_cdev, &leds_list, node) { 350 down_write(&led_cdev->trigger_lock); 351 if (led_cdev->trigger == trig) 352 led_trigger_set(led_cdev, NULL); 353 up_write(&led_cdev->trigger_lock); 354 } 355 up_read(&leds_list_lock); 356 } 357 EXPORT_SYMBOL_GPL(led_trigger_unregister); 358 359 static void devm_led_trigger_release(struct device *dev, void *res) 360 { 361 led_trigger_unregister(*(struct led_trigger **)res); 362 } 363 364 int devm_led_trigger_register(struct device *dev, 365 struct led_trigger *trig) 366 { 367 struct led_trigger **dr; 368 int rc; 369 370 dr = devres_alloc(devm_led_trigger_release, sizeof(*dr), 371 GFP_KERNEL); 372 if (!dr) 373 return -ENOMEM; 374 375 *dr = trig; 376 377 rc = led_trigger_register(trig); 378 if (rc) 379 devres_free(dr); 380 else 381 devres_add(dev, dr); 382 383 return rc; 384 } 385 EXPORT_SYMBOL_GPL(devm_led_trigger_register); 386 387 /* Simple LED Trigger Interface */ 388 389 void led_trigger_event(struct led_trigger *trig, 390 enum led_brightness brightness) 391 { 392 struct led_classdev *led_cdev; 393 394 if (!trig) 395 return; 396 397 trig->brightness = brightness; 398 399 rcu_read_lock(); 400 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) 401 led_set_brightness(led_cdev, brightness); 402 rcu_read_unlock(); 403 } 404 EXPORT_SYMBOL_GPL(led_trigger_event); 405 406 void led_mc_trigger_event(struct led_trigger *trig, 407 unsigned int *intensity_value, unsigned int num_colors, 408 enum led_brightness brightness) 409 { 410 struct led_classdev *led_cdev; 411 412 if (!trig) 413 return; 414 415 rcu_read_lock(); 416 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) { 417 if (!(led_cdev->flags & LED_MULTI_COLOR)) 418 continue; 419 420 led_mc_set_brightness(led_cdev, intensity_value, num_colors, brightness); 421 } 422 rcu_read_unlock(); 423 } 424 EXPORT_SYMBOL_GPL(led_mc_trigger_event); 425 426 static void led_trigger_blink_setup(struct led_trigger *trig, 427 unsigned long delay_on, 428 unsigned long delay_off, 429 int oneshot, 430 int invert) 431 { 432 struct led_classdev *led_cdev; 433 434 if (!trig) 435 return; 436 437 rcu_read_lock(); 438 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) { 439 if (oneshot) 440 led_blink_set_oneshot(led_cdev, &delay_on, &delay_off, 441 invert); 442 else 443 led_blink_set_nosleep(led_cdev, delay_on, delay_off); 444 } 445 rcu_read_unlock(); 446 } 447 448 void led_trigger_blink(struct led_trigger *trig, 449 unsigned long delay_on, 450 unsigned long delay_off) 451 { 452 led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0); 453 } 454 EXPORT_SYMBOL_GPL(led_trigger_blink); 455 456 void led_trigger_blink_oneshot(struct led_trigger *trig, 457 unsigned long delay_on, 458 unsigned long delay_off, 459 int invert) 460 { 461 led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert); 462 } 463 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot); 464 465 void led_trigger_register_simple(const char *name, struct led_trigger **tp) 466 { 467 struct led_trigger *trig; 468 int err; 469 470 trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL); 471 472 if (trig) { 473 trig->name = name; 474 err = led_trigger_register(trig); 475 if (err < 0) { 476 kfree(trig); 477 trig = NULL; 478 pr_warn("LED trigger %s failed to register (%d)\n", 479 name, err); 480 } 481 } else { 482 pr_warn("LED trigger %s failed to register (no memory)\n", 483 name); 484 } 485 *tp = trig; 486 } 487 EXPORT_SYMBOL_GPL(led_trigger_register_simple); 488 489 void led_trigger_unregister_simple(struct led_trigger *trig) 490 { 491 if (trig) 492 led_trigger_unregister(trig); 493 kfree(trig); 494 } 495 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple); 496