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 unsigned long flags; 161 char *event = NULL; 162 char *envp[2]; 163 const char *name; 164 int ret; 165 166 if (!led_cdev->trigger && !trig) 167 return 0; 168 169 name = trig ? trig->name : "none"; 170 event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name); 171 172 /* Remove any existing trigger */ 173 if (led_cdev->trigger) { 174 write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags); 175 list_del(&led_cdev->trig_list); 176 write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock, 177 flags); 178 cancel_work_sync(&led_cdev->set_brightness_work); 179 led_stop_software_blink(led_cdev); 180 if (led_cdev->trigger->deactivate) 181 led_cdev->trigger->deactivate(led_cdev); 182 device_remove_groups(led_cdev->dev, led_cdev->trigger->groups); 183 led_cdev->trigger = NULL; 184 led_cdev->trigger_data = NULL; 185 led_cdev->activated = false; 186 led_set_brightness(led_cdev, LED_OFF); 187 } 188 if (trig) { 189 write_lock_irqsave(&trig->leddev_list_lock, flags); 190 list_add_tail(&led_cdev->trig_list, &trig->led_cdevs); 191 write_unlock_irqrestore(&trig->leddev_list_lock, flags); 192 led_cdev->trigger = trig; 193 194 if (trig->activate) 195 ret = trig->activate(led_cdev); 196 else 197 ret = 0; 198 199 if (ret) 200 goto err_activate; 201 202 ret = device_add_groups(led_cdev->dev, trig->groups); 203 if (ret) { 204 dev_err(led_cdev->dev, "Failed to add trigger attributes\n"); 205 goto err_add_groups; 206 } 207 } 208 209 if (event) { 210 envp[0] = event; 211 envp[1] = NULL; 212 if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp)) 213 dev_err(led_cdev->dev, 214 "%s: Error sending uevent\n", __func__); 215 kfree(event); 216 } 217 218 return 0; 219 220 err_add_groups: 221 222 if (trig->deactivate) 223 trig->deactivate(led_cdev); 224 err_activate: 225 226 write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags); 227 list_del(&led_cdev->trig_list); 228 write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock, flags); 229 led_cdev->trigger = NULL; 230 led_cdev->trigger_data = NULL; 231 led_set_brightness(led_cdev, LED_OFF); 232 kfree(event); 233 234 return ret; 235 } 236 EXPORT_SYMBOL_GPL(led_trigger_set); 237 238 void led_trigger_remove(struct led_classdev *led_cdev) 239 { 240 down_write(&led_cdev->trigger_lock); 241 led_trigger_set(led_cdev, NULL); 242 up_write(&led_cdev->trigger_lock); 243 } 244 EXPORT_SYMBOL_GPL(led_trigger_remove); 245 246 void led_trigger_set_default(struct led_classdev *led_cdev) 247 { 248 struct led_trigger *trig; 249 250 if (!led_cdev->default_trigger) 251 return; 252 253 down_read(&triggers_list_lock); 254 down_write(&led_cdev->trigger_lock); 255 list_for_each_entry(trig, &trigger_list, next_trig) { 256 if (!strcmp(led_cdev->default_trigger, trig->name) && 257 trigger_relevant(led_cdev, trig)) { 258 led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER; 259 led_trigger_set(led_cdev, trig); 260 break; 261 } 262 } 263 up_write(&led_cdev->trigger_lock); 264 up_read(&triggers_list_lock); 265 } 266 EXPORT_SYMBOL_GPL(led_trigger_set_default); 267 268 void led_trigger_rename_static(const char *name, struct led_trigger *trig) 269 { 270 /* new name must be on a temporary string to prevent races */ 271 BUG_ON(name == trig->name); 272 273 down_write(&triggers_list_lock); 274 /* this assumes that trig->name was originaly allocated to 275 * non constant storage */ 276 strcpy((char *)trig->name, name); 277 up_write(&triggers_list_lock); 278 } 279 EXPORT_SYMBOL_GPL(led_trigger_rename_static); 280 281 /* LED Trigger Interface */ 282 283 int led_trigger_register(struct led_trigger *trig) 284 { 285 struct led_classdev *led_cdev; 286 struct led_trigger *_trig; 287 288 rwlock_init(&trig->leddev_list_lock); 289 INIT_LIST_HEAD(&trig->led_cdevs); 290 291 down_write(&triggers_list_lock); 292 /* Make sure the trigger's name isn't already in use */ 293 list_for_each_entry(_trig, &trigger_list, next_trig) { 294 if (!strcmp(_trig->name, trig->name) && 295 (trig->trigger_type == _trig->trigger_type || 296 !trig->trigger_type || !_trig->trigger_type)) { 297 up_write(&triggers_list_lock); 298 return -EEXIST; 299 } 300 } 301 /* Add to the list of led triggers */ 302 list_add_tail(&trig->next_trig, &trigger_list); 303 up_write(&triggers_list_lock); 304 305 /* Register with any LEDs that have this as a default trigger */ 306 down_read(&leds_list_lock); 307 list_for_each_entry(led_cdev, &leds_list, node) { 308 down_write(&led_cdev->trigger_lock); 309 if (!led_cdev->trigger && led_cdev->default_trigger && 310 !strcmp(led_cdev->default_trigger, trig->name) && 311 trigger_relevant(led_cdev, trig)) { 312 led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER; 313 led_trigger_set(led_cdev, trig); 314 } 315 up_write(&led_cdev->trigger_lock); 316 } 317 up_read(&leds_list_lock); 318 319 return 0; 320 } 321 EXPORT_SYMBOL_GPL(led_trigger_register); 322 323 void led_trigger_unregister(struct led_trigger *trig) 324 { 325 struct led_classdev *led_cdev; 326 327 if (list_empty_careful(&trig->next_trig)) 328 return; 329 330 /* Remove from the list of led triggers */ 331 down_write(&triggers_list_lock); 332 list_del_init(&trig->next_trig); 333 up_write(&triggers_list_lock); 334 335 /* Remove anyone actively using this trigger */ 336 down_read(&leds_list_lock); 337 list_for_each_entry(led_cdev, &leds_list, node) { 338 down_write(&led_cdev->trigger_lock); 339 if (led_cdev->trigger == trig) 340 led_trigger_set(led_cdev, NULL); 341 up_write(&led_cdev->trigger_lock); 342 } 343 up_read(&leds_list_lock); 344 } 345 EXPORT_SYMBOL_GPL(led_trigger_unregister); 346 347 static void devm_led_trigger_release(struct device *dev, void *res) 348 { 349 led_trigger_unregister(*(struct led_trigger **)res); 350 } 351 352 int devm_led_trigger_register(struct device *dev, 353 struct led_trigger *trig) 354 { 355 struct led_trigger **dr; 356 int rc; 357 358 dr = devres_alloc(devm_led_trigger_release, sizeof(*dr), 359 GFP_KERNEL); 360 if (!dr) 361 return -ENOMEM; 362 363 *dr = trig; 364 365 rc = led_trigger_register(trig); 366 if (rc) 367 devres_free(dr); 368 else 369 devres_add(dev, dr); 370 371 return rc; 372 } 373 EXPORT_SYMBOL_GPL(devm_led_trigger_register); 374 375 /* Simple LED Trigger Interface */ 376 377 void led_trigger_event(struct led_trigger *trig, 378 enum led_brightness brightness) 379 { 380 struct led_classdev *led_cdev; 381 unsigned long flags; 382 383 if (!trig) 384 return; 385 386 read_lock_irqsave(&trig->leddev_list_lock, flags); 387 list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) 388 led_set_brightness(led_cdev, brightness); 389 read_unlock_irqrestore(&trig->leddev_list_lock, flags); 390 } 391 EXPORT_SYMBOL_GPL(led_trigger_event); 392 393 static void led_trigger_blink_setup(struct led_trigger *trig, 394 unsigned long *delay_on, 395 unsigned long *delay_off, 396 int oneshot, 397 int invert) 398 { 399 struct led_classdev *led_cdev; 400 unsigned long flags; 401 402 if (!trig) 403 return; 404 405 read_lock_irqsave(&trig->leddev_list_lock, flags); 406 list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) { 407 if (oneshot) 408 led_blink_set_oneshot(led_cdev, delay_on, delay_off, 409 invert); 410 else 411 led_blink_set(led_cdev, delay_on, delay_off); 412 } 413 read_unlock_irqrestore(&trig->leddev_list_lock, flags); 414 } 415 416 void led_trigger_blink(struct led_trigger *trig, 417 unsigned long *delay_on, 418 unsigned long *delay_off) 419 { 420 led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0); 421 } 422 EXPORT_SYMBOL_GPL(led_trigger_blink); 423 424 void led_trigger_blink_oneshot(struct led_trigger *trig, 425 unsigned long *delay_on, 426 unsigned long *delay_off, 427 int invert) 428 { 429 led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert); 430 } 431 EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot); 432 433 void led_trigger_register_simple(const char *name, struct led_trigger **tp) 434 { 435 struct led_trigger *trig; 436 int err; 437 438 trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL); 439 440 if (trig) { 441 trig->name = name; 442 err = led_trigger_register(trig); 443 if (err < 0) { 444 kfree(trig); 445 trig = NULL; 446 pr_warn("LED trigger %s failed to register (%d)\n", 447 name, err); 448 } 449 } else { 450 pr_warn("LED trigger %s failed to register (no memory)\n", 451 name); 452 } 453 *tp = trig; 454 } 455 EXPORT_SYMBOL_GPL(led_trigger_register_simple); 456 457 void led_trigger_unregister_simple(struct led_trigger *trig) 458 { 459 if (trig) 460 led_trigger_unregister(trig); 461 kfree(trig); 462 } 463 EXPORT_SYMBOL_GPL(led_trigger_unregister_simple); 464