dell-led.c
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/*
* dell_led.c - Dell LED Driver
*
* 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 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);