leds-ot200.c

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/*
 * Bachmann ot200 leds driver.
 *
 * Author: Sebastian Andrzej Siewior <[email protected]>
 *         Christian Gmeiner <[email protected]>
 *
 * License: GPL as published by the FSF.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/leds.h>
#include <linux/io.h>
#include <linux/module.h>


struct ot200_led {
    struct led_classdev cdev;
    const char *name;
    unsigned long port;
    u8 mask;
};

/*
 * The device has three leds on the back panel (led_err, led_init and led_run)
 * and can handle up to seven leds on the front panel.
 */

static struct ot200_led leds[] = {
    {
        .name = "led_run",
        .port = 0x5a,
        .mask = BIT(0),
    },
    {
        .name = "led_init",
        .port = 0x5a,
        .mask = BIT(1),
    },
    {
        .name = "led_err",
        .port = 0x5a,
        .mask = BIT(2),
    },
    {
        .name = "led_1",
        .port = 0x49,
        .mask = BIT(7),
    },
    {
        .name = "led_2",
        .port = 0x49,
        .mask = BIT(6),
    },
    {
        .name = "led_3",
        .port = 0x49,
        .mask = BIT(5),
    },
    {
        .name = "led_4",
        .port = 0x49,
        .mask = BIT(4),
    },
    {
        .name = "led_5",
        .port = 0x49,
        .mask = BIT(3),
    },
    {
        .name = "led_6",
        .port = 0x49,
        .mask = BIT(2),
    },
    {
        .name = "led_7",
        .port = 0x49,
        .mask = BIT(1),
    }
};

static DEFINE_SPINLOCK(value_lock);

/*
 * we need to store the current led states, as it is not
 * possible to read the current led state via inb().
 */
static u8 leds_back;
static u8 leds_front;

static void ot200_led_brightness_set(struct led_classdev *led_cdev,
        enum led_brightness value)
{
    struct ot200_led *led = container_of(led_cdev, struct ot200_led, cdev);
    u8 *val;
    unsigned long flags;

    spin_lock_irqsave(&value_lock, flags);

    if (led->port == 0x49)
        val = &leds_front;
    else if (led->port == 0x5a)
        val = &leds_back;
    else
        BUG();

    if (value == LED_OFF)
        *val &= ~led->mask;
    else
        *val |= led->mask;

    outb(*val, led->port);
    spin_unlock_irqrestore(&value_lock, flags);
}

static int __devinit ot200_led_probe(struct platform_device *pdev)
{
    int i;
    int ret;

    for (i = 0; i < ARRAY_SIZE(leds); i++) {

        leds[i].cdev.name = leds[i].name;
        leds[i].cdev.brightness_set = ot200_led_brightness_set;

        ret = led_classdev_register(&pdev->dev, &leds[i].cdev);
        if (ret < 0)
            goto err;
    }

    leds_front = 0;     /* turn off all front leds */
    leds_back = BIT(1); /* turn on init led */
    outb(leds_front, 0x49);
    outb(leds_back, 0x5a);

    return 0;

err:
    for (i = i - 1; i >= 0; i--)
        led_classdev_unregister(&leds[i].cdev);

    return ret;
}

static int __devexit ot200_led_remove(struct platform_device *pdev)
{
    int i;

    for (i = 0; i < ARRAY_SIZE(leds); i++)
        led_classdev_unregister(&leds[i].cdev);

    return 0;
}

static struct platform_driver ot200_led_driver = {
    .probe      = ot200_led_probe,
    .remove     = __devexit_p(ot200_led_remove),
    .driver     = {
        .name   = "leds-ot200",
        .owner  = THIS_MODULE,
    },
};

module_platform_driver(ot200_led_driver);

MODULE_AUTHOR("Sebastian A. Siewior <[email protected]>");
MODULE_DESCRIPTION("ot200 LED driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:leds-ot200");