2 * dell_led.c - Dell LED Driver
4 * Copyright (C) 2010 Dell Inc.
5 * Louis Davis <louis_davis@dell.com>
6 * Jim Dailey <jim_dailey@dell.com>
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.
14 #include <linux/acpi.h>
15 #include <linux/leds.h>
17 MODULE_AUTHOR("Louis Davis/Jim Dailey");
18 MODULE_DESCRIPTION("Dell LED Control Driver");
19 MODULE_LICENSE("GPL");
21 #define DELL_LED_BIOS_GUID "F6E4FE6E-909D-47cb-8BAB-C9F6F2F8D396"
22 MODULE_ALIAS("wmi:" DELL_LED_BIOS_GUID);
24 /* Error Result Codes: */
25 #define INVALID_DEVICE_ID 250
26 #define INVALID_PARAMETER 251
27 #define INVALID_BUFFER 252
28 #define INTERFACE_ERROR 253
29 #define UNSUPPORTED_COMMAND 254
30 #define UNSPECIFIED_ERROR 255
33 #define DEVICE_ID_PANEL_BACK 1
37 #define CMD_LED_OFF 17
38 #define CMD_LED_BLINK 18
42 unsigned char result_code;
43 unsigned char device_id;
44 unsigned char command;
45 unsigned char on_time;
46 unsigned char off_time;
49 static int dell_led_perform_fn(u8 length,
56 struct bios_args *bios_return;
58 union acpi_object *obj;
59 struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
60 struct acpi_buffer input;
63 struct bios_args args;
65 args.result_code = result_code;
66 args.device_id = device_id;
67 args.command = command;
68 args.on_time = on_time;
69 args.off_time = off_time;
71 input.length = sizeof(struct bios_args);
72 input.pointer = &args;
74 status = wmi_evaluate_method(DELL_LED_BIOS_GUID,
80 if (ACPI_FAILURE(status))
87 else if (obj->type != ACPI_TYPE_BUFFER) {
92 bios_return = ((struct bios_args *)obj->buffer.pointer);
93 return_code = bios_return->result_code;
100 static int led_on(void)
102 return dell_led_perform_fn(3, /* Length of command */
103 INTERFACE_ERROR, /* Init to INTERFACE_ERROR */
104 DEVICE_ID_PANEL_BACK, /* Device ID */
105 CMD_LED_ON, /* Command */
110 static int led_off(void)
112 return dell_led_perform_fn(3, /* Length of command */
113 INTERFACE_ERROR, /* Init to INTERFACE_ERROR */
114 DEVICE_ID_PANEL_BACK, /* Device ID */
115 CMD_LED_OFF, /* Command */
120 static int led_blink(unsigned char on_eighths,
121 unsigned char off_eighths)
123 return dell_led_perform_fn(5, /* Length of command */
124 INTERFACE_ERROR, /* Init to INTERFACE_ERROR */
125 DEVICE_ID_PANEL_BACK, /* Device ID */
126 CMD_LED_BLINK, /* Command */
127 on_eighths, /* blink on in eigths of a second */
128 off_eighths); /* blink off in eights of a second */
131 static void dell_led_set(struct led_classdev *led_cdev,
132 enum led_brightness value)
134 if (value == LED_OFF)
140 static int dell_led_blink(struct led_classdev *led_cdev,
141 unsigned long *delay_on,
142 unsigned long *delay_off)
144 unsigned long on_eighths;
145 unsigned long off_eighths;
147 /* The Dell LED delay is based on 125ms intervals.
148 Need to round up to next interval. */
150 on_eighths = (*delay_on + 124) / 125;
153 if (on_eighths > 255)
155 *delay_on = on_eighths * 125;
157 off_eighths = (*delay_off + 124) / 125;
158 if (0 == off_eighths)
160 if (off_eighths > 255)
162 *delay_off = off_eighths * 125;
164 led_blink(on_eighths, off_eighths);
169 static struct led_classdev dell_led = {
171 .brightness = LED_OFF,
173 .brightness_set = dell_led_set,
174 .blink_set = dell_led_blink,
175 .flags = LED_CORE_SUSPENDRESUME,
178 static int __init dell_led_init(void)
182 if (!wmi_has_guid(DELL_LED_BIOS_GUID))
189 return led_classdev_register(NULL, &dell_led);
192 static void __exit dell_led_exit(void)
194 led_classdev_unregister(&dell_led);
199 module_init(dell_led_init);
200 module_exit(dell_led_exit);