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