led-class.c

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/*
 * LED Class Core
 *
 * Copyright (C) 2005 John Lenz <[email protected]>
 * Copyright (C) 2005-2007 Richard Purdie <[email protected]>
 *
 * 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>
#include <linux/err.h>
#include <linux/ctype.h>
#include <linux/leds.h>
#include "leds.h"

static struct class *leds_class;

static void led_update_brightness(struct led_classdev *led_cdev)
{
    if (led_cdev->brightness_get)
        led_cdev->brightness = led_cdev->brightness_get(led_cdev);
}

static ssize_t led_brightness_show(struct device *dev,
        struct device_attribute *attr, char *buf)
{
    struct led_classdev *led_cdev = dev_get_drvdata(dev);

    /* no lock needed for this */
    led_update_brightness(led_cdev);

    return sprintf(buf, "%u\n", led_cdev->brightness);
}

static ssize_t led_brightness_store(struct device *dev,
        struct device_attribute *attr, const char *buf, size_t size)
{
    struct led_classdev *led_cdev = dev_get_drvdata(dev);
    unsigned long state;
    ssize_t ret = -EINVAL;

    ret = kstrtoul(buf, 10, &state);
    if (ret)
        return ret;

    if (state == LED_OFF)
        led_trigger_remove(led_cdev);
    __led_set_brightness(led_cdev, state);

    return size;
}

static ssize_t led_max_brightness_show(struct device *dev,
        struct device_attribute *attr, char *buf)
{
    struct led_classdev *led_cdev = dev_get_drvdata(dev);

    return sprintf(buf, "%u\n", led_cdev->max_brightness);
}

static struct device_attribute led_class_attrs[] = {
    __ATTR(brightness, 0644, led_brightness_show, led_brightness_store),
    __ATTR(max_brightness, 0444, led_max_brightness_show, NULL),
#ifdef CONFIG_LEDS_TRIGGERS
    __ATTR(trigger, 0644, led_trigger_show, led_trigger_store),
#endif
    __ATTR_NULL,
};

static void led_timer_function(unsigned long data)
{
    struct led_classdev *led_cdev = (void *)data;
    unsigned long brightness;
    unsigned long delay;

    if (!led_cdev->blink_delay_on || !led_cdev->blink_delay_off) {
        __led_set_brightness(led_cdev, LED_OFF);
        return;
    }

    if (led_cdev->flags & LED_BLINK_ONESHOT_STOP) {
        led_cdev->flags &= ~LED_BLINK_ONESHOT_STOP;
        return;
    }

    brightness = led_get_brightness(led_cdev);
    if (!brightness) {
        /* Time to switch the LED on. */
        brightness = led_cdev->blink_brightness;
        delay = led_cdev->blink_delay_on;
    } else {
        /* Store the current brightness value to be able
         * to restore it when the delay_off period is over.
         */
        led_cdev->blink_brightness = brightness;
        brightness = LED_OFF;
        delay = led_cdev->blink_delay_off;
    }

    __led_set_brightness(led_cdev, brightness);

    /* Return in next iteration if led is in one-shot mode and we are in
     * the final blink state so that the led is toggled each delay_on +
     * delay_off milliseconds in worst case.
     */
    if (led_cdev->flags & LED_BLINK_ONESHOT) {
        if (led_cdev->flags & LED_BLINK_INVERT) {
            if (brightness)
                led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
        } else {
            if (!brightness)
                led_cdev->flags |= LED_BLINK_ONESHOT_STOP;
        }
    }

    mod_timer(&led_cdev->blink_timer, jiffies + msecs_to_jiffies(delay));
}

static void set_brightness_delayed(struct work_struct *ws)
{
    struct led_classdev *led_cdev =
        container_of(ws, struct led_classdev, set_brightness_work);

    led_stop_software_blink(led_cdev);

    __led_set_brightness(led_cdev, led_cdev->delayed_set_value);
}

void led_classdev_suspend(struct led_classdev *led_cdev)
{
    led_cdev->flags |= LED_SUSPENDED;
    led_cdev->brightness_set(led_cdev, 0);
}
EXPORT_SYMBOL_GPL(led_classdev_suspend);

void led_classdev_resume(struct led_classdev *led_cdev)
{
    led_cdev->brightness_set(led_cdev, led_cdev->brightness);
    led_cdev->flags &= ~LED_SUSPENDED;
}
EXPORT_SYMBOL_GPL(led_classdev_resume);

static int led_suspend(struct device *dev, pm_message_t state)
{
    struct led_classdev *led_cdev = dev_get_drvdata(dev);

    if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
        led_classdev_suspend(led_cdev);

    return 0;
}

static int led_resume(struct device *dev)
{
    struct led_classdev *led_cdev = dev_get_drvdata(dev);

    if (led_cdev->flags & LED_CORE_SUSPENDRESUME)
        led_classdev_resume(led_cdev);

    return 0;
}

int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
{
    led_cdev->dev = device_create(leds_class, parent, 0, led_cdev,
                      "%s", led_cdev->name);
    if (IS_ERR(led_cdev->dev))
        return PTR_ERR(led_cdev->dev);

#ifdef CONFIG_LEDS_TRIGGERS
    init_rwsem(&led_cdev->trigger_lock);
#endif
    /* add to the list of leds */
    down_write(&leds_list_lock);
    list_add_tail(&led_cdev->node, &leds_list);
    up_write(&leds_list_lock);

    if (!led_cdev->max_brightness)
        led_cdev->max_brightness = LED_FULL;

    led_update_brightness(led_cdev);

    INIT_WORK(&led_cdev->set_brightness_work, set_brightness_delayed);

    init_timer(&led_cdev->blink_timer);
    led_cdev->blink_timer.function = led_timer_function;
    led_cdev->blink_timer.data = (unsigned long)led_cdev;

#ifdef CONFIG_LEDS_TRIGGERS
    led_trigger_set_default(led_cdev);
#endif

    printk(KERN_DEBUG "Registered led device: %s\n",
            led_cdev->name);

    return 0;
}
EXPORT_SYMBOL_GPL(led_classdev_register);

void led_classdev_unregister(struct led_classdev *led_cdev)
{
#ifdef CONFIG_LEDS_TRIGGERS
    down_write(&led_cdev->trigger_lock);
    if (led_cdev->trigger)
        led_trigger_set(led_cdev, NULL);
    up_write(&led_cdev->trigger_lock);
#endif

    cancel_work_sync(&led_cdev->set_brightness_work);

    /* Stop blinking */
    led_stop_software_blink(led_cdev);
    led_set_brightness(led_cdev, LED_OFF);

    device_unregister(led_cdev->dev);

    down_write(&leds_list_lock);
    list_del(&led_cdev->node);
    up_write(&leds_list_lock);
}
EXPORT_SYMBOL_GPL(led_classdev_unregister);

static int __init leds_init(void)
{
    leds_class = class_create(THIS_MODULE, "leds");
    if (IS_ERR(leds_class))
        return PTR_ERR(leds_class);
    leds_class->suspend = led_suspend;
    leds_class->resume = led_resume;
    leds_class->dev_attrs = led_class_attrs;
    return 0;
}

static void __exit leds_exit(void)
{
    class_destroy(leds_class);
}

subsys_initcall(leds_init);
module_exit(leds_exit);

MODULE_AUTHOR("John Lenz, Richard Purdie");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("LED Class Interface");