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![Heiner Kallweit](/assets/img/avatar_default.png)
If a simple trigger is assigned to a LED, then the LED may be off until the next led_trigger_event() call. This may be an issue for simple triggers with rare led_trigger_event() calls, e.g. power supply charging indicators (drivers/power/supply/power_supply_leds.c). Therefore persist the brightness value of the last led_trigger_event() call and use this value if the trigger is assigned to a LED. In addition add a getter for the trigger brightness value. Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> Reviewed-by: Takashi Iwai <tiwai@suse.de> Link: https://lore.kernel.org/r/b1358b25-3f30-458d-8240-5705ae007a8a@gmail.com Signed-off-by: Lee Jones <lee@kernel.org>
469 lines
11 KiB
C
469 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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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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#include <linux/export.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 <linux/mm.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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static inline bool
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trigger_relevant(struct led_classdev *led_cdev, struct led_trigger *trig)
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{
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return !trig->trigger_type || trig->trigger_type == led_cdev->trigger_type;
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}
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ssize_t led_trigger_write(struct file *filp, struct kobject *kobj,
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struct bin_attribute *bin_attr, char *buf,
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loff_t pos, size_t count)
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{
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struct device *dev = kobj_to_dev(kobj);
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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 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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if (sysfs_streq(buf, "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 (sysfs_streq(buf, trig->name) && trigger_relevant(led_cdev, trig)) {
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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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/* we come here only if buf matches no trigger */
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ret = -EINVAL;
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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_write);
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__printf(3, 4)
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static int led_trigger_snprintf(char *buf, ssize_t size, const char *fmt, ...)
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{
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va_list args;
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int i;
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va_start(args, fmt);
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if (size <= 0)
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i = vsnprintf(NULL, 0, fmt, args);
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else
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i = vscnprintf(buf, size, fmt, args);
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va_end(args);
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return i;
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}
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static int led_trigger_format(char *buf, size_t size,
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struct led_classdev *led_cdev)
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{
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struct led_trigger *trig;
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int len = led_trigger_snprintf(buf, size, "%s",
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led_cdev->trigger ? "none" : "[none]");
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list_for_each_entry(trig, &trigger_list, next_trig) {
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bool hit;
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if (!trigger_relevant(led_cdev, trig))
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continue;
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hit = led_cdev->trigger && !strcmp(led_cdev->trigger->name, trig->name);
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len += led_trigger_snprintf(buf + len, size - len,
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" %s%s%s", hit ? "[" : "",
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trig->name, hit ? "]" : "");
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}
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len += led_trigger_snprintf(buf + len, size - len, "\n");
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return len;
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}
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/*
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* It was stupid to create 10000 cpu triggers, but we are stuck with it now.
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* Don't make that mistake again. We work around it here by creating binary
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* attribute, which is not limited by length. This is _not_ good design, do not
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* copy it.
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*/
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ssize_t led_trigger_read(struct file *filp, struct kobject *kobj,
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struct bin_attribute *attr, char *buf,
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loff_t pos, size_t count)
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{
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struct device *dev = kobj_to_dev(kobj);
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struct led_classdev *led_cdev = dev_get_drvdata(dev);
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void *data;
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int len;
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down_read(&triggers_list_lock);
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down_read(&led_cdev->trigger_lock);
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len = led_trigger_format(NULL, 0, led_cdev);
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data = kvmalloc(len + 1, GFP_KERNEL);
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if (!data) {
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up_read(&led_cdev->trigger_lock);
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up_read(&triggers_list_lock);
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return -ENOMEM;
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}
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len = led_trigger_format(data, len + 1, led_cdev);
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up_read(&led_cdev->trigger_lock);
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up_read(&triggers_list_lock);
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len = memory_read_from_buffer(buf, count, &pos, data, len);
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kvfree(data);
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return len;
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}
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EXPORT_SYMBOL_GPL(led_trigger_read);
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/* Caller must ensure led_cdev->trigger_lock held */
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int led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trig)
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{
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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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int ret;
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if (!led_cdev->trigger && !trig)
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return 0;
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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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spin_lock(&led_cdev->trigger->leddev_list_lock);
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list_del_rcu(&led_cdev->trig_list);
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spin_unlock(&led_cdev->trigger->leddev_list_lock);
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/* ensure it's no longer visible on the led_cdevs list */
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synchronize_rcu();
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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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device_remove_groups(led_cdev->dev, led_cdev->trigger->groups);
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led_cdev->trigger = NULL;
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led_cdev->trigger_data = NULL;
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led_cdev->activated = false;
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led_cdev->flags &= ~LED_INIT_DEFAULT_TRIGGER;
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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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spin_lock(&trig->leddev_list_lock);
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list_add_tail_rcu(&led_cdev->trig_list, &trig->led_cdevs);
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spin_unlock(&trig->leddev_list_lock);
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led_cdev->trigger = trig;
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ret = 0;
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if (trig->activate)
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ret = trig->activate(led_cdev);
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else
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led_set_brightness(led_cdev, trig->brightness);
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if (ret)
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goto err_activate;
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ret = device_add_groups(led_cdev->dev, trig->groups);
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if (ret) {
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dev_err(led_cdev->dev, "Failed to add trigger attributes\n");
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goto err_add_groups;
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}
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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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if (kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp))
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dev_err(led_cdev->dev,
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"%s: Error sending uevent\n", __func__);
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kfree(event);
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}
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return 0;
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err_add_groups:
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if (trig->deactivate)
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trig->deactivate(led_cdev);
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err_activate:
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spin_lock(&led_cdev->trigger->leddev_list_lock);
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list_del_rcu(&led_cdev->trig_list);
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spin_unlock(&led_cdev->trigger->leddev_list_lock);
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synchronize_rcu();
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led_cdev->trigger = NULL;
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led_cdev->trigger_data = NULL;
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led_set_brightness(led_cdev, LED_OFF);
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kfree(event);
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return ret;
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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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static bool led_match_default_trigger(struct led_classdev *led_cdev,
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struct led_trigger *trig)
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{
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if (!strcmp(led_cdev->default_trigger, trig->name) &&
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trigger_relevant(led_cdev, trig)) {
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led_cdev->flags |= LED_INIT_DEFAULT_TRIGGER;
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led_trigger_set(led_cdev, trig);
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return true;
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}
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return false;
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}
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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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bool found = false;
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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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found = led_match_default_trigger(led_cdev, trig);
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if (found)
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break;
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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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* If default trigger wasn't found, maybe trigger module isn't loaded yet.
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* Once loaded it will re-probe with all led_cdev's.
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*/
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if (!found)
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request_module_nowait("ledtrig:%s", led_cdev->default_trigger);
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}
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EXPORT_SYMBOL_GPL(led_trigger_set_default);
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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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spin_lock_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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(trig->trigger_type == _trig->trigger_type ||
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!trig->trigger_type || !_trig->trigger_type)) {
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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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led_match_default_trigger(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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static void devm_led_trigger_release(struct device *dev, void *res)
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{
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led_trigger_unregister(*(struct led_trigger **)res);
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}
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int devm_led_trigger_register(struct device *dev,
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struct led_trigger *trig)
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{
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struct led_trigger **dr;
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int rc;
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dr = devres_alloc(devm_led_trigger_release, sizeof(*dr),
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GFP_KERNEL);
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if (!dr)
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return -ENOMEM;
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*dr = trig;
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rc = led_trigger_register(trig);
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if (rc)
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devres_free(dr);
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else
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devres_add(dev, dr);
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return rc;
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}
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EXPORT_SYMBOL_GPL(devm_led_trigger_register);
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/* Simple LED Trigger 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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trig->brightness = brightness;
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rcu_read_lock();
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list_for_each_entry_rcu(led_cdev, &trig->led_cdevs, trig_list)
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led_set_brightness(led_cdev, brightness);
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rcu_read_unlock();
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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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rcu_read_lock();
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list_for_each_entry_rcu(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_nosleep(led_cdev, delay_on, delay_off);
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}
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rcu_read_unlock();
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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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