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![Jacek Anaszewski](/assets/img/avatar_default.png)
Add a mechanism for locking LED subsystem sysfs interface. This patch prepares ground for addition of LED Flash Class extension, whose API will be integrated with V4L2 Flash API. Such a fusion enforces introducing a locking scheme, which will secure consistent access to the LED Flash Class device. The mechanism being introduced allows for disabling LED subsystem sysfs interface by calling led_sysfs_disable function and enabling it by calling led_sysfs_enable. The functions alter the LED_SYSFS_DISABLE flag state and must be called under mutex lock. The state of the lock is checked with use of led_sysfs_is_disabled function. Such a design allows for providing immediate feedback to the user space on whether the LED Flash Class device is available or is under V4L2 Flash sub-device control. Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com> Acked-by: Kyungmin Park <kyungmin.park@samsung.com> Cc: Richard Purdie <rpurdie@rpsys.net> Signed-off-by: Bryan Wu <cooloney@gmail.com>
342 lines
8.5 KiB
C
342 lines
8.5 KiB
C
/*
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* LED Triggers Core
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*
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* Copyright 2005-2007 Openedhand Ltd.
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*
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* Author: Richard Purdie <rpurdie@openedhand.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <linux/device.h>
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#include <linux/timer.h>
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#include <linux/rwsem.h>
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#include <linux/leds.h>
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#include <linux/slab.h>
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#include "leds.h"
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/*
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* Nests outside led_cdev->trigger_lock
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*/
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static DECLARE_RWSEM(triggers_list_lock);
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static LIST_HEAD(trigger_list);
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/* Used by LED Class */
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ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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char trigger_name[TRIG_NAME_MAX];
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struct led_trigger *trig;
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size_t len;
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int ret = count;
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mutex_lock(&led_cdev->led_access);
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if (led_sysfs_is_disabled(led_cdev)) {
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ret = -EBUSY;
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goto unlock;
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}
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trigger_name[sizeof(trigger_name) - 1] = '\0';
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strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
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len = strlen(trigger_name);
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if (len && trigger_name[len - 1] == '\n')
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trigger_name[len - 1] = '\0';
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if (!strcmp(trigger_name, "none")) {
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led_trigger_remove(led_cdev);
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goto unlock;
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}
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down_read(&triggers_list_lock);
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list_for_each_entry(trig, &trigger_list, next_trig) {
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if (!strcmp(trigger_name, trig->name)) {
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down_write(&led_cdev->trigger_lock);
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led_trigger_set(led_cdev, trig);
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up_write(&led_cdev->trigger_lock);
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up_read(&triggers_list_lock);
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goto unlock;
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}
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}
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up_read(&triggers_list_lock);
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unlock:
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mutex_unlock(&led_cdev->led_access);
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return ret;
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}
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EXPORT_SYMBOL_GPL(led_trigger_store);
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ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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struct led_trigger *trig;
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int len = 0;
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down_read(&triggers_list_lock);
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down_read(&led_cdev->trigger_lock);
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if (!led_cdev->trigger)
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len += sprintf(buf+len, "[none] ");
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else
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len += sprintf(buf+len, "none ");
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list_for_each_entry(trig, &trigger_list, next_trig) {
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if (led_cdev->trigger && !strcmp(led_cdev->trigger->name,
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trig->name))
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len += sprintf(buf+len, "[%s] ", trig->name);
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else
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len += sprintf(buf+len, "%s ", trig->name);
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}
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up_read(&led_cdev->trigger_lock);
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up_read(&triggers_list_lock);
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len += sprintf(len+buf, "\n");
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return len;
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}
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EXPORT_SYMBOL_GPL(led_trigger_show);
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/* Caller must ensure led_cdev->trigger_lock held */
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void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
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{
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unsigned long flags;
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char *event = NULL;
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char *envp[2];
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const char *name;
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name = trig ? trig->name : "none";
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event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
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/* Remove any existing trigger */
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if (led_cdev->trigger) {
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write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
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list_del(&led_cdev->trig_list);
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write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
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flags);
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cancel_work_sync(&led_cdev->set_brightness_work);
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led_stop_software_blink(led_cdev);
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if (led_cdev->trigger->deactivate)
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led_cdev->trigger->deactivate(led_cdev);
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led_cdev->trigger = NULL;
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led_set_brightness(led_cdev, LED_OFF);
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}
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if (trig) {
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write_lock_irqsave(&trig->leddev_list_lock, flags);
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list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
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write_unlock_irqrestore(&trig->leddev_list_lock, flags);
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led_cdev->trigger = trig;
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if (trig->activate)
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trig->activate(led_cdev);
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}
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if (event) {
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envp[0] = event;
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envp[1] = NULL;
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kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp);
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kfree(event);
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}
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}
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EXPORT_SYMBOL_GPL(led_trigger_set);
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void led_trigger_remove(struct led_classdev *led_cdev)
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{
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down_write(&led_cdev->trigger_lock);
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led_trigger_set(led_cdev, NULL);
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up_write(&led_cdev->trigger_lock);
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}
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EXPORT_SYMBOL_GPL(led_trigger_remove);
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void led_trigger_set_default(struct led_classdev *led_cdev)
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{
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struct led_trigger *trig;
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if (!led_cdev->default_trigger)
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return;
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down_read(&triggers_list_lock);
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down_write(&led_cdev->trigger_lock);
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list_for_each_entry(trig, &trigger_list, next_trig) {
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if (!strcmp(led_cdev->default_trigger, trig->name))
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led_trigger_set(led_cdev, trig);
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}
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up_write(&led_cdev->trigger_lock);
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up_read(&triggers_list_lock);
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}
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EXPORT_SYMBOL_GPL(led_trigger_set_default);
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void led_trigger_rename_static(const char *name, struct led_trigger *trig)
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{
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/* new name must be on a temporary string to prevent races */
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BUG_ON(name == trig->name);
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down_write(&triggers_list_lock);
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/* this assumes that trig->name was originaly allocated to
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* non constant storage */
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strcpy((char *)trig->name, name);
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up_write(&triggers_list_lock);
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}
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EXPORT_SYMBOL_GPL(led_trigger_rename_static);
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/* LED Trigger Interface */
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int led_trigger_register(struct led_trigger *trig)
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{
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struct led_classdev *led_cdev;
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struct led_trigger *_trig;
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rwlock_init(&trig->leddev_list_lock);
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INIT_LIST_HEAD(&trig->led_cdevs);
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down_write(&triggers_list_lock);
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/* Make sure the trigger's name isn't already in use */
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list_for_each_entry(_trig, &trigger_list, next_trig) {
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if (!strcmp(_trig->name, trig->name)) {
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up_write(&triggers_list_lock);
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return -EEXIST;
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}
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}
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/* Add to the list of led triggers */
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list_add_tail(&trig->next_trig, &trigger_list);
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up_write(&triggers_list_lock);
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/* Register with any LEDs that have this as a default trigger */
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down_read(&leds_list_lock);
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list_for_each_entry(led_cdev, &leds_list, node) {
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down_write(&led_cdev->trigger_lock);
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if (!led_cdev->trigger && led_cdev->default_trigger &&
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!strcmp(led_cdev->default_trigger, trig->name))
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led_trigger_set(led_cdev, trig);
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up_write(&led_cdev->trigger_lock);
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}
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up_read(&leds_list_lock);
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return 0;
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}
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EXPORT_SYMBOL_GPL(led_trigger_register);
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void led_trigger_unregister(struct led_trigger *trig)
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{
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struct led_classdev *led_cdev;
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if (list_empty_careful(&trig->next_trig))
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return;
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/* Remove from the list of led triggers */
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down_write(&triggers_list_lock);
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list_del_init(&trig->next_trig);
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up_write(&triggers_list_lock);
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/* Remove anyone actively using this trigger */
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down_read(&leds_list_lock);
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list_for_each_entry(led_cdev, &leds_list, node) {
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down_write(&led_cdev->trigger_lock);
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if (led_cdev->trigger == trig)
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led_trigger_set(led_cdev, NULL);
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up_write(&led_cdev->trigger_lock);
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}
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up_read(&leds_list_lock);
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}
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EXPORT_SYMBOL_GPL(led_trigger_unregister);
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/* Simple LED Tigger Interface */
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void led_trigger_event(struct led_trigger *trig,
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enum led_brightness brightness)
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{
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struct led_classdev *led_cdev;
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if (!trig)
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return;
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read_lock(&trig->leddev_list_lock);
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list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list)
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led_set_brightness(led_cdev, brightness);
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read_unlock(&trig->leddev_list_lock);
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}
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EXPORT_SYMBOL_GPL(led_trigger_event);
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static void led_trigger_blink_setup(struct led_trigger *trig,
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unsigned long *delay_on,
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unsigned long *delay_off,
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int oneshot,
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int invert)
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{
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struct led_classdev *led_cdev;
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if (!trig)
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return;
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read_lock(&trig->leddev_list_lock);
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list_for_each_entry(led_cdev, &trig->led_cdevs, trig_list) {
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if (oneshot)
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led_blink_set_oneshot(led_cdev, delay_on, delay_off,
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invert);
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else
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led_blink_set(led_cdev, delay_on, delay_off);
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}
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read_unlock(&trig->leddev_list_lock);
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}
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void led_trigger_blink(struct led_trigger *trig,
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unsigned long *delay_on,
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unsigned long *delay_off)
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{
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led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
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}
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EXPORT_SYMBOL_GPL(led_trigger_blink);
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void led_trigger_blink_oneshot(struct led_trigger *trig,
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unsigned long *delay_on,
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unsigned long *delay_off,
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int invert)
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{
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led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
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}
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EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
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void led_trigger_register_simple(const char *name, struct led_trigger **tp)
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{
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struct led_trigger *trig;
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int err;
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trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
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if (trig) {
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trig->name = name;
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err = led_trigger_register(trig);
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if (err < 0) {
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kfree(trig);
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trig = NULL;
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pr_warn("LED trigger %s failed to register (%d)\n",
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name, err);
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}
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} else {
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pr_warn("LED trigger %s failed to register (no memory)\n",
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name);
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}
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*tp = trig;
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}
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EXPORT_SYMBOL_GPL(led_trigger_register_simple);
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void led_trigger_unregister_simple(struct led_trigger *trig)
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{
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if (trig)
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led_trigger_unregister(trig);
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kfree(trig);
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}
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EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
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MODULE_AUTHOR("Richard Purdie");
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("LED Triggers Core");
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