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