dell-led.c

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/*
 * dell_led.c - Dell LED Driver
 *
 * Copyright (C) 2010 Dell Inc.
 * Louis Davis <[email protected]>
 * Jim Dailey <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 */

#include <linux/acpi.h>
#include <linux/leds.h>
#include <linux/slab.h>
#include <linux/module.h>

MODULE_AUTHOR("Louis Davis/Jim Dailey");
MODULE_DESCRIPTION("Dell LED Control Driver");
MODULE_LICENSE("GPL");

#define DELL_LED_BIOS_GUID "F6E4FE6E-909D-47cb-8BAB-C9F6F2F8D396"
MODULE_ALIAS("wmi:" DELL_LED_BIOS_GUID);

/* Error Result Codes: */
#define INVALID_DEVICE_ID   250
#define INVALID_PARAMETER   251
#define INVALID_BUFFER      252
#define INTERFACE_ERROR     253
#define UNSUPPORTED_COMMAND 254
#define UNSPECIFIED_ERROR   255

/* Device ID */
#define DEVICE_ID_PANEL_BACK    1

/* LED Commands */
#define CMD_LED_ON  16
#define CMD_LED_OFF 17
#define CMD_LED_BLINK   18

struct bios_args {
    unsigned char length;
    unsigned char result_code;
    unsigned char device_id;
    unsigned char command;
    unsigned char on_time;
    unsigned char off_time;
};

static int dell_led_perform_fn(u8 length,
        u8 result_code,
        u8 device_id,
        u8 command,
        u8 on_time,
        u8 off_time)
{
    struct bios_args *bios_return;
    u8 return_code;
    union acpi_object *obj;
    struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
    struct acpi_buffer input;
    acpi_status status;

    struct bios_args args;
    args.length = length;
    args.result_code = result_code;
    args.device_id = device_id;
    args.command = command;
    args.on_time = on_time;
    args.off_time = off_time;

    input.length = sizeof(struct bios_args);
    input.pointer = &args;

    status = wmi_evaluate_method(DELL_LED_BIOS_GUID,
        1,
        1,
        &input,
        &output);

    if (ACPI_FAILURE(status))
        return status;

    obj = output.pointer;

    if (!obj)
        return -EINVAL;
    else if (obj->type != ACPI_TYPE_BUFFER) {
        kfree(obj);
        return -EINVAL;
    }

    bios_return = ((struct bios_args *)obj->buffer.pointer);
    return_code = bios_return->result_code;

    kfree(obj);

    return return_code;
}

static int led_on(void)
{
    return dell_led_perform_fn(3,   /* Length of command */
        INTERFACE_ERROR,    /* Init to  INTERFACE_ERROR */
        DEVICE_ID_PANEL_BACK,   /* Device ID */
        CMD_LED_ON,     /* Command */
        0,          /* not used */
        0);         /* not used */
}

static int led_off(void)
{
    return dell_led_perform_fn(3,   /* Length of command */
        INTERFACE_ERROR,    /* Init to  INTERFACE_ERROR */
        DEVICE_ID_PANEL_BACK,   /* Device ID */
        CMD_LED_OFF,        /* Command */
        0,          /* not used */
        0);         /* not used */
}

static int led_blink(unsigned char on_eighths,
        unsigned char off_eighths)
{
    return dell_led_perform_fn(5,   /* Length of command */
        INTERFACE_ERROR,    /* Init to  INTERFACE_ERROR */
        DEVICE_ID_PANEL_BACK,   /* Device ID */
        CMD_LED_BLINK,      /* Command */
        on_eighths,     /* blink on in eigths of a second */
        off_eighths);       /* blink off in eights of a second */
}

static void dell_led_set(struct led_classdev *led_cdev,
        enum led_brightness value)
{
    if (value == LED_OFF)
        led_off();
    else
        led_on();
}

static int dell_led_blink(struct led_classdev *led_cdev,
        unsigned long *delay_on,
        unsigned long *delay_off)
{
    unsigned long on_eighths;
    unsigned long off_eighths;

    /* The Dell LED delay is based on 125ms intervals.
       Need to round up to next interval. */

    on_eighths = (*delay_on + 124) / 125;
    if (0 == on_eighths)
        on_eighths = 1;
    if (on_eighths > 255)
        on_eighths = 255;
    *delay_on = on_eighths * 125;

    off_eighths = (*delay_off + 124) / 125;
    if (0 == off_eighths)
        off_eighths = 1;
    if (off_eighths > 255)
        off_eighths = 255;
    *delay_off = off_eighths * 125;

    led_blink(on_eighths, off_eighths);

    return 0;
}

static struct led_classdev dell_led = {
    .name       = "dell::lid",
    .brightness = LED_OFF,
    .max_brightness = 1,
    .brightness_set = dell_led_set,
    .blink_set  = dell_led_blink,
    .flags      = LED_CORE_SUSPENDRESUME,
};

static int __init dell_led_init(void)
{
    int error = 0;

    if (!wmi_has_guid(DELL_LED_BIOS_GUID))
        return -ENODEV;

    error = led_off();
    if (error != 0)
        return -ENODEV;

    return led_classdev_register(NULL, &dell_led);
}

static void __exit dell_led_exit(void)
{
    led_classdev_unregister(&dell_led);

    led_off();
}

module_init(dell_led_init);
module_exit(dell_led_exit);