linux/drivers/leds/dell-led.c
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   1/*
   2 * dell_led.c - Dell LED Driver
   3 *
   4 * Copyright (C) 2010 Dell Inc.
   5 * Louis Davis <louis_davis@dell.com>
   6 * Jim Dailey <jim_dailey@dell.com>
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License as
  10 * published by the Free Software Foundation.
  11 *
  12 */
  13
  14#include <linux/acpi.h>
  15#include <linux/leds.h>
  16#include <linux/slab.h>
  17#include <linux/module.h>
  18
  19MODULE_AUTHOR("Louis Davis/Jim Dailey");
  20MODULE_DESCRIPTION("Dell LED Control Driver");
  21MODULE_LICENSE("GPL");
  22
  23#define DELL_LED_BIOS_GUID "F6E4FE6E-909D-47cb-8BAB-C9F6F2F8D396"
  24MODULE_ALIAS("wmi:" DELL_LED_BIOS_GUID);
  25
  26/* Error Result Codes: */
  27#define INVALID_DEVICE_ID       250
  28#define INVALID_PARAMETER       251
  29#define INVALID_BUFFER          252
  30#define INTERFACE_ERROR         253
  31#define UNSUPPORTED_COMMAND     254
  32#define UNSPECIFIED_ERROR       255
  33
  34/* Device ID */
  35#define DEVICE_ID_PANEL_BACK    1
  36
  37/* LED Commands */
  38#define CMD_LED_ON      16
  39#define CMD_LED_OFF     17
  40#define CMD_LED_BLINK   18
  41
  42struct bios_args {
  43        unsigned char length;
  44        unsigned char result_code;
  45        unsigned char device_id;
  46        unsigned char command;
  47        unsigned char on_time;
  48        unsigned char off_time;
  49};
  50
  51static int dell_led_perform_fn(u8 length,
  52                u8 result_code,
  53                u8 device_id,
  54                u8 command,
  55                u8 on_time,
  56                u8 off_time)
  57{
  58        struct bios_args *bios_return;
  59        u8 return_code;
  60        union acpi_object *obj;
  61        struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
  62        struct acpi_buffer input;
  63        acpi_status status;
  64
  65        struct bios_args args;
  66        args.length = length;
  67        args.result_code = result_code;
  68        args.device_id = device_id;
  69        args.command = command;
  70        args.on_time = on_time;
  71        args.off_time = off_time;
  72
  73        input.length = sizeof(struct bios_args);
  74        input.pointer = &args;
  75
  76        status = wmi_evaluate_method(DELL_LED_BIOS_GUID,
  77                1,
  78                1,
  79                &input,
  80                &output);
  81
  82        if (ACPI_FAILURE(status))
  83                return status;
  84
  85        obj = output.pointer;
  86
  87        if (!obj)
  88                return -EINVAL;
  89        else if (obj->type != ACPI_TYPE_BUFFER) {
  90                kfree(obj);
  91                return -EINVAL;
  92        }
  93
  94        bios_return = ((struct bios_args *)obj->buffer.pointer);
  95        return_code = bios_return->result_code;
  96
  97        kfree(obj);
  98
  99        return return_code;
 100}
 101
 102static int led_on(void)
 103{
 104        return dell_led_perform_fn(3,   /* Length of command */
 105                INTERFACE_ERROR,        /* Init to  INTERFACE_ERROR */
 106                DEVICE_ID_PANEL_BACK,   /* Device ID */
 107                CMD_LED_ON,             /* Command */
 108                0,                      /* not used */
 109                0);                     /* not used */
 110}
 111
 112static int led_off(void)
 113{
 114        return dell_led_perform_fn(3,   /* Length of command */
 115                INTERFACE_ERROR,        /* Init to  INTERFACE_ERROR */
 116                DEVICE_ID_PANEL_BACK,   /* Device ID */
 117                CMD_LED_OFF,            /* Command */
 118                0,                      /* not used */
 119                0);                     /* not used */
 120}
 121
 122static int led_blink(unsigned char on_eighths,
 123                unsigned char off_eighths)
 124{
 125        return dell_led_perform_fn(5,   /* Length of command */
 126                INTERFACE_ERROR,        /* Init to  INTERFACE_ERROR */
 127                DEVICE_ID_PANEL_BACK,   /* Device ID */
 128                CMD_LED_BLINK,          /* Command */
 129                on_eighths,             /* blink on in eigths of a second */
 130                off_eighths);           /* blink off in eights of a second */
 131}
 132
 133static void dell_led_set(struct led_classdev *led_cdev,
 134                enum led_brightness value)
 135{
 136        if (value == LED_OFF)
 137                led_off();
 138        else
 139                led_on();
 140}
 141
 142static int dell_led_blink(struct led_classdev *led_cdev,
 143                unsigned long *delay_on,
 144                unsigned long *delay_off)
 145{
 146        unsigned long on_eighths;
 147        unsigned long off_eighths;
 148
 149        /* The Dell LED delay is based on 125ms intervals.
 150           Need to round up to next interval. */
 151
 152        on_eighths = (*delay_on + 124) / 125;
 153        if (0 == on_eighths)
 154                on_eighths = 1;
 155        if (on_eighths > 255)
 156                on_eighths = 255;
 157        *delay_on = on_eighths * 125;
 158
 159        off_eighths = (*delay_off + 124) / 125;
 160        if (0 == off_eighths)
 161                off_eighths = 1;
 162        if (off_eighths > 255)
 163                off_eighths = 255;
 164        *delay_off = off_eighths * 125;
 165
 166        led_blink(on_eighths, off_eighths);
 167
 168        return 0;
 169}
 170
 171static struct led_classdev dell_led = {
 172        .name           = "dell::lid",
 173        .brightness     = LED_OFF,
 174        .max_brightness = 1,
 175        .brightness_set = dell_led_set,
 176        .blink_set      = dell_led_blink,
 177        .flags          = LED_CORE_SUSPENDRESUME,
 178};
 179
 180static int __init dell_led_init(void)
 181{
 182        int error = 0;
 183
 184        if (!wmi_has_guid(DELL_LED_BIOS_GUID))
 185                return -ENODEV;
 186
 187        error = led_off();
 188        if (error != 0)
 189                return -ENODEV;
 190
 191        return led_classdev_register(NULL, &dell_led);
 192}
 193
 194static void __exit dell_led_exit(void)
 195{
 196        led_classdev_unregister(&dell_led);
 197
 198        led_off();
 199}
 200
 201module_init(dell_led_init);
 202module_exit(dell_led_exit);
 203
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