led-triggers.c 8.1 KB
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/*
 * LED Triggers Core
 *
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 * Copyright 2005-2007 Openedhand Ltd.
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 *
 * Author: Richard Purdie <rpurdie@openedhand.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#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"

/*
 * Nests outside led_cdev->trigger_lock
 */
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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,
		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];
	struct led_trigger *trig;
	size_t len;

	trigger_name[sizeof(trigger_name) - 1] = '\0';
	strncpy(trigger_name, buf, sizeof(trigger_name) - 1);
	len = strlen(trigger_name);

	if (len && trigger_name[len - 1] == '\n')
		trigger_name[len - 1] = '\0';

	if (!strcmp(trigger_name, "none")) {
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		led_trigger_remove(led_cdev);
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		return count;
	}

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	down_read(&triggers_list_lock);
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	list_for_each_entry(trig, &trigger_list, next_trig) {
		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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			return count;
		}
	}
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	up_read(&triggers_list_lock);
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	return -EINVAL;
}
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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,
		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;
	int len = 0;

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	down_read(&triggers_list_lock);
	down_read(&led_cdev->trigger_lock);
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	if (!led_cdev->trigger)
		len += sprintf(buf+len, "[none] ");
	else
		len += sprintf(buf+len, "none ");

	list_for_each_entry(trig, &trigger_list, next_trig) {
		if (led_cdev->trigger && !strcmp(led_cdev->trigger->name,
							trig->name))
			len += sprintf(buf+len, "[%s] ", trig->name);
		else
			len += sprintf(buf+len, "%s ", trig->name);
	}
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	up_read(&led_cdev->trigger_lock);
	up_read(&triggers_list_lock);
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	len += sprintf(len+buf, "\n");
	return len;
}
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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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{
	unsigned long flags;
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	char *event = NULL;
	char *envp[2];
	const char *name;

	name = trig ? trig->name : "none";
	event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
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	/* Remove any existing trigger */
	if (led_cdev->trigger) {
		write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
		list_del(&led_cdev->trig_list);
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		write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
			flags);
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		cancel_work_sync(&led_cdev->set_brightness_work);
		led_stop_software_blink(led_cdev);
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		if (led_cdev->trigger->deactivate)
			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) {
		write_lock_irqsave(&trig->leddev_list_lock, flags);
		list_add_tail(&led_cdev->trig_list, &trig->led_cdevs);
		write_unlock_irqrestore(&trig->leddev_list_lock, flags);
		led_cdev->trigger = trig;
		if (trig->activate)
			trig->activate(led_cdev);
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	}
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	if (event) {
		envp[0] = event;
		envp[1] = NULL;
		kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp);
		kfree(event);
	}
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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)
{
	down_write(&led_cdev->trigger_lock);
	led_trigger_set(led_cdev, NULL);
	up_write(&led_cdev->trigger_lock);
}
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EXPORT_SYMBOL_GPL(led_trigger_remove);
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void led_trigger_set_default(struct led_classdev *led_cdev)
{
	struct led_trigger *trig;

	if (!led_cdev->default_trigger)
		return;

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	down_read(&triggers_list_lock);
	down_write(&led_cdev->trigger_lock);
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	list_for_each_entry(trig, &trigger_list, next_trig) {
		if (!strcmp(led_cdev->default_trigger, trig->name))
			led_trigger_set(led_cdev, trig);
	}
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	up_write(&led_cdev->trigger_lock);
	up_read(&triggers_list_lock);
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}
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EXPORT_SYMBOL_GPL(led_trigger_set_default);

/* LED Trigger Interface */
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int led_trigger_register(struct led_trigger *trig)
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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);
	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) {
		if (!strcmp(_trig->name, trig->name)) {
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			up_write(&triggers_list_lock);
			return -EEXIST;
		}
	}
	/* 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))
			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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EXPORT_SYMBOL_GPL(led_trigger_register);
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void led_trigger_unregister(struct led_trigger *trig)
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{
	struct led_classdev *led_cdev;

	/* Remove from the list of led triggers */
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	down_write(&triggers_list_lock);
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	list_del(&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 list_head *entry;

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	if (!trig)
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		return;

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	read_lock(&trig->leddev_list_lock);
	list_for_each(entry, &trig->led_cdevs) {
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		struct led_classdev *led_cdev;

		led_cdev = list_entry(entry, struct led_classdev, trig_list);
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		led_set_brightness(led_cdev, brightness);
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	}
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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,
			     unsigned long *delay_off,
			     int oneshot,
			     int invert)
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{
	struct list_head *entry;

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	if (!trig)
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		return;

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	read_lock(&trig->leddev_list_lock);
	list_for_each(entry, &trig->led_cdevs) {
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		struct led_classdev *led_cdev;

		led_cdev = list_entry(entry, struct led_classdev, trig_list);
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		if (oneshot)
			led_blink_set_oneshot(led_cdev, delay_on, delay_off,
					      invert);
		else
			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,
		       unsigned long *delay_on,
		       unsigned long *delay_off)
{
	led_trigger_blink_setup(trig, delay_on, delay_off, 0, 0);
}
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EXPORT_SYMBOL_GPL(led_trigger_blink);

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void led_trigger_blink_oneshot(struct led_trigger *trig,
			       unsigned long *delay_on,
			       unsigned long *delay_off,
			       int invert)
{
	led_trigger_blink_setup(trig, delay_on, delay_off, 1, invert);
}
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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	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) {
		trig->name = name;
		err = led_trigger_register(trig);
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		if (err < 0) {
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			kfree(trig);
			trig = NULL;
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			printk(KERN_WARNING "LED trigger %s failed to register"
				" (%d)\n", name, err);
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		}
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	} else
		printk(KERN_WARNING "LED trigger %s failed to register"
			" (no memory)\n", name);

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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)
		led_trigger_unregister(trig);
	kfree(trig);
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}
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EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);

MODULE_AUTHOR("Richard Purdie");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LED Triggers Core");