/*
 * Copyright (C) 2010 Dell Inc.
 * Louis Davis <louis_davis@dell.com>
 * Jim Dailey <jim_dailey@dell.com>
 *
 * 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 acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
        struct bios_args *bios_return;
        struct acpi_buffer input;
        union acpi_object *obj;
        acpi_status status;
        u8 return_code;

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

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

        status = wmi_evaluate_method(DELL_LED_BIOS_GUID, 0, 1, &input, &output);
        if (ACPI_FAILURE(status))
                return status;

        obj = output.pointer;

        if (!obj)
                return -EINVAL;
        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 = DIV_ROUND_UP(*delay_on, 125);
        on_eighths = clamp_t(unsigned long, on_eighths, 1, 255);
        *delay_on = on_eighths * 125;

        off_eighths = DIV_ROUND_UP(*delay_off, 125);
        off_eighths = clamp_t(unsigned long, off_eighths, 1, 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);