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 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 if (trig->activate) 198 ret = trig->activate(led_cdev); 199 else 200 ret = 0; 201 202 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 void led_trigger_set_default(struct led_classdev *led_cdev) 251 { 252 struct led_trigger *trig; 253 254 if (!led_cdev->default_trigger) 255 return; 256 257 down_read(&triggers_list_lock); 258 down_write(&led_cdev->trigger_lock); 259 list_for_each_entry(trig, &trigger_list, next_trig) { 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 break; 265 } 266 } 267 up_write(&led_cdev->trigger_lock); 268 up_read(&triggers_list_lock); 269 } 270 EXPORT_SYMBOL_GPL(led_trigger_set_default); 271 272 void led_trigger_rename_static(const char *name, struct led_trigger *trig) 273 { 274 /* new name must be on a temporary string to prevent races */ 275 BUG_ON(name == trig->name); 276 277 down_write(&triggers_list_lock); 278 /* this assumes that trig->name was originaly allocated to 279 * non constant storage */ 280 strcpy((char *)trig->name, name); 281 up_write(&triggers_list_lock); 282 } 283 EXPORT_SYMBOL_GPL(led_trigger_rename_static); 284 285 /* LED Trigger Interface */ 286 287 int led_trigger_register(struct led_trigger *trig) 288 { 289 struct led_classdev *led_cdev; 290 struct led_trigger *_trig; 291 292 spin_lock_init(&trig->leddev_list_lock); 293 INIT_LIST_HEAD(&trig->led_cdevs); 294 295 down_write(&triggers_list_lock); 296 /* Make sure the trigger's name isn't already in use */ 297 list_for_each_entry(_trig, &trigger_list, next_trig) { 298 if (!strcmp(_trig->name, trig->name) && 299 (trig->trigger_type == _trig->trigger_type || 300 !trig->trigger_type || !_trig->trigger_type)) { 301 up_write(&triggers_list_lock); 302 return -EEXIST; 303 } 304 } 305 /* Add to the list of led triggers */ 306 list_add_tail(&trig->next_trig, &trigger_list); 307 up_write(&triggers_list_lock); 308 309 /* Register with any LEDs that have this as a default trigger */ 310 down_read(&leds_list_lock); 311 list_for_each_entry(led_cdev, &leds_list, node) { 312 down_write(&led_cdev->trigger_lock); 313 if (!led_cdev->trigger && led_cdev->default_trigger && 314 !strcmp(led_cdev->default_trigger, trig->name) && 315 trigger_relevant(led_cdev, trig)) { 316 led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER; 317 led_trigger_set(led_cdev, trig); 318 } 319 up_write(&led_cdev->trigger_lock); 320 } 321 up_read(&leds_list_lock); 322 323 return 0; 324 } 325 EXPORT_SYMBOL_GPL(led_trigger_register); 326 327 void led_trigger_unregister(struct led_trigger *trig) 328 { 329 struct led_classdev *led_cdev; 330 331 if (list_empty_careful(&trig->next_trig)) 332 return; 333 334 /* Remove from the list of led triggers */ 335 down_write(&triggers_list_lock); 336 list_del_init(&trig->next_trig); 337 up_write(&triggers_list_lock); 338 339 /* Remove anyone actively using this trigger */ 340 down_read(&leds_list_lock); 341 list_for_each_entry(led_cdev, &leds_list, node) { 342 down_write(&led_cdev->trigger_lock); 343 if (led_cdev->trigger == trig) 344 led_trigger_set(led_cdev, NULL); 345 up_write(&led_cdev->trigger_lock); 346 } 347 up_read(&leds_list_lock); 348 } 349 EXPORT_SYMBOL_GPL(led_trigger_unregister); 350 351 static void devm_led_trigger_release(struct device *dev, void *res) 352 { 353 led_trigger_unregister(*(struct led_trigger **)res); 354 } 355 356 int devm_led_trigger_register(struct device *dev, 357 struct led_trigger *trig) 358 { 359 struct led_trigger **dr; 360 int rc; 361 362 dr = devres_alloc(devm_led_trigger_release, sizeof(*dr), 363 GFP_KERNEL); 364 if (!dr) 365 return -ENOMEM; 366 367 *dr = trig; 368 369 rc = led_trigger_register(trig); 370 if (rc) 371 devres_free(dr); 372 else 373 devres_add(dev, dr); 374 375 return rc; 376 } 377 EXPORT_SYMBOL_GPL(devm_led_trigger_register); 378 379 /* Simple LED Trigger Interface */ 380 381 void led_trigger_event(struct led_trigger *trig, 382 enum led_brightness brightness) 383 { 384 struct led_classdev *led_cdev; 385 386 if (!trig) 387 return; 388 389 rcu_read_lock(); 390 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) 391 led_set_brightness(led_cdev, brightness); 392 rcu_read_unlock(); 393 } 394 EXPORT_SYMBOL_GPL(led_trigger_event); 395 396 static void led_trigger_blink_setup(struct led_trigger *trig, 397 unsigned long delay_on, 398 unsigned long delay_off, 399 int oneshot, 400 int invert) 401 { 402 struct led_classdev *led_cdev; 403 404 if (!trig) 405 return; 406 407 rcu_read_lock(); 408 list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list) { 409 if (oneshot) 410 led_blink_set_oneshot(led_cdev, &delay_on, &delay_off, 411 invert); 412 else 413 led_blink_set_nosleep(led_cdev, delay_on, delay_off); 414 } 415 rcu_read_unlock(); 416 } 417 418 void led_trigger_blink(struct led_trigger *trig, 419 unsigned long delay_on, 420 unsigned long delay_off) 421 { 422 led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0); 423 } 424 EXPORT_SYMBOL_GPL(led_trigger_blink); 425 426 void led_trigger_blink_oneshot(struct led_trigger *trig, 427 unsigned long delay_on, 428 unsigned long delay_off, 429 int invert) 430 { 431 led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert); 432 } 433 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot); 434 435 void led_trigger_register_simple(const char *name, struct led_trigger **tp) 436 { 437 struct led_trigger *trig; 438 int err; 439 440 trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL); 441 442 if (trig) { 443 trig->name = name; 444 err = led_trigger_register(trig); 445 if (err < 0) { 446 kfree(trig); 447 trig = NULL; 448 pr_warn("LED trigger %s failed to register (%d)\n", 449 name, err); 450 } 451 } else { 452 pr_warn("LED trigger %s failed to register (no memory)\n", 453 name); 454 } 455 *tp = trig; 456 } 457 EXPORT_SYMBOL_GPL(led_trigger_register_simple); 458 459 void led_trigger_unregister_simple(struct led_trigger *trig) 460 { 461 if (trig) 462 led_trigger_unregister(trig); 463 kfree(trig); 464 } 465 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple); 466