/*
 * LED Triggers Core
 *
 * Copyright 2005-2007 Openedhand Ltd.
 *
 * 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/sysdev.h>
#include <linux/timer.h>
#include <linux/rwsem.h>
#include <linux/leds.h>
#include "leds.h"

/*
 * Nests outside led_cdev->trigger_lock
 */
static DECLARE_RWSEM(triggers_list_lock);
static LIST_HEAD(trigger_list);

 /* Used by LED Class */

ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
                const char *buf, size_t count)
{
        struct led_classdev *led_cdev = dev_get_drvdata(dev);
        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")) {
                led_trigger_remove(led_cdev);
                return count;
        }

        down_read(&triggers_list_lock);
        list_for_each_entry(trig, &trigger_list, next_trig) {
                if (!strcmp(trigger_name, trig->name)) {
                        down_write(&led_cdev->trigger_lock);
                        led_trigger_set(led_cdev, trig);
                        up_write(&led_cdev->trigger_lock);

                        up_read(&triggers_list_lock);
                        return count;
                }
        }
        up_read(&triggers_list_lock);

        return -EINVAL;
}
EXPORT_SYMBOL_GPL(led_trigger_store);

ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
                char *buf)
{
        struct led_classdev *led_cdev = dev_get_drvdata(dev);
        struct led_trigger *trig;
        int len = 0;

        down_read(&triggers_list_lock);
        down_read(&led_cdev->trigger_lock);

        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);
        }
        up_read(&led_cdev->trigger_lock);
        up_read(&triggers_list_lock);

        len += sprintf(len+buf, "\n");
        return len;
}
EXPORT_SYMBOL_GPL(led_trigger_show);

/* Caller must ensure led_cdev->trigger_lock held */
void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trigger)
{
        unsigned long flags;

        /* Remove any existing trigger */
        if (led_cdev->trigger) {
                write_lock_irqsave(&led_cdev->trigger->leddev_list_lock, flags);
                list_del(&led_cdev->trig_list);
                write_unlock_irqrestore(&led_cdev->trigger->leddev_list_lock,
                        flags);
                if (led_cdev->trigger->deactivate)
                        led_cdev->trigger->deactivate(led_cdev);
                led_cdev->trigger = NULL;
                led_set_brightness(led_cdev, LED_OFF);
        }
        if (trigger) {
                write_lock_irqsave(&trigger->leddev_list_lock, flags);
                list_add_tail(&led_cdev->trig_list, &trigger->led_cdevs);
                write_unlock_irqrestore(&trigger->leddev_list_lock, flags);
                led_cdev->trigger = trigger;
                if (trigger->activate)
                        trigger->activate(led_cdev);
        }
}
EXPORT_SYMBOL_GPL(led_trigger_set);

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);
}
EXPORT_SYMBOL_GPL(led_trigger_remove);

void led_trigger_set_default(struct led_classdev *led_cdev)
{
        struct led_trigger *trig;

        if (!led_cdev->default_trigger)
                return;

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

/* LED Trigger Interface */

int led_trigger_register(struct led_trigger *trigger)
{
        struct led_classdev *led_cdev;
        struct led_trigger *trig;

        rwlock_init(&trigger->leddev_list_lock);
        INIT_LIST_HEAD(&trigger->led_cdevs);

        down_write(&triggers_list_lock);
        /* Make sure the trigger's name isn't already in use */
        list_for_each_entry(trig, &trigger_list, next_trig) {
                if (!strcmp(trig->name, trigger->name)) {
                        up_write(&triggers_list_lock);
                        return -EEXIST;
                }
        }
        /* Add to the list of led triggers */
        list_add_tail(&trigger->next_trig, &trigger_list);
        up_write(&triggers_list_lock);

        /* Register with any LEDs that have this as a default trigger */
        down_read(&leds_list_lock);
        list_for_each_entry(led_cdev, &leds_list, node) {
                down_write(&led_cdev->trigger_lock);
                if (!led_cdev->trigger && led_cdev->default_trigger &&
                            !strcmp(led_cdev->default_trigger, trigger->name))
                        led_trigger_set(led_cdev, trigger);
                up_write(&led_cdev->trigger_lock);
        }
        up_read(&leds_list_lock);

        return 0;
}
EXPORT_SYMBOL_GPL(led_trigger_register);

void led_trigger_unregister(struct led_trigger *trigger)
{
        struct led_classdev *led_cdev;

        /* Remove from the list of led triggers */
        down_write(&triggers_list_lock);
        list_del(&trigger->next_trig);
        up_write(&triggers_list_lock);

        /* Remove anyone actively using this trigger */
        down_read(&leds_list_lock);
        list_for_each_entry(led_cdev, &leds_list, node) {
                down_write(&led_cdev->trigger_lock);
                if (led_cdev->trigger == trigger)
                        led_trigger_set(led_cdev, NULL);
                up_write(&led_cdev->trigger_lock);
        }
        up_read(&leds_list_lock);
}
EXPORT_SYMBOL_GPL(led_trigger_unregister);

/* Simple LED Tigger Interface */

void led_trigger_event(struct led_trigger *trigger,
                        enum led_brightness brightness)
{
        struct list_head *entry;

        if (!trigger)
                return;

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

                led_cdev = list_entry(entry, struct led_classdev, trig_list);
                led_set_brightness(led_cdev, brightness);
        }
        read_unlock(&trigger->leddev_list_lock);
}
EXPORT_SYMBOL_GPL(led_trigger_event);

void led_trigger_register_simple(const char *name, struct led_trigger **tp)
{
        struct led_trigger *trigger;
        int err;

        trigger = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);

        if (trigger) {
                trigger->name = name;
                err = led_trigger_register(trigger);
                if (err < 0)
                        printk(KERN_WARNING "LED trigger %s failed to register"
                                " (%d)\n", name, err);
        } else
                printk(KERN_WARNING "LED trigger %s failed to register"
                        " (no memory)\n", name);

        *tp = trigger;
}
EXPORT_SYMBOL_GPL(led_trigger_register_simple);

void led_trigger_unregister_simple(struct led_trigger *trigger)
{
        if (trigger)
                led_trigger_unregister(trigger);
        kfree(trigger);
}
EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);

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