Root/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
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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