drivers/leds/dell-led.c

   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
  19 MODULE_AUTHOR("Louis Davis/Jim Dailey");
  20 MODULE_DESCRIPTION("Dell LED Control Driver");
  21 MODULE_LICENSE("GPL");
  22
  23 #define DELL_LED_BIOS_GUID "F6E4FE6E-909D-47cb-8BAB-C9F6F2F8D396"
  24 MODULE_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
  42 struct 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
  51 static 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
 102 static 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
 112 static 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
 122 static 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
 133 static 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
 142 static 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
 171 static 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
 180 static 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
 194 static void __exit dell_led_exit(void)
 195 {
 196         led_classdev_unregister(&dell_led);
 197
 198         led_off();
 199 }
 200
 201 module_init(dell_led_init);
 202 module_exit(dell_led_exit);