1/*
2 *  Backlight Driver for Intel-based Apples
3 *
4 *  Copyright (c) Red Hat <mjg@redhat.com>
5 *  Based on code from Pommed:
6 *  Copyright (C) 2006 Nicolas Boichat <nicolas @boichat.ch>
7 *  Copyright (C) 2006 Felipe Alfaro Solana <felipe_alfaro @linuxmail.org>
8 *  Copyright (C) 2007 Julien BLACHE <jb@jblache.org>
9 *
10 *  This program is free software; you can redistribute it and/or modify
11 *  it under the terms of the GNU General Public License version 2 as
12 *  published by the Free Software Foundation.
13 *
14 *  This driver triggers SMIs which cause the firmware to change the
15 *  backlight brightness. This is icky in many ways, but it's impractical to
16 *  get at the firmware code in order to figure out what it's actually doing.
17 */
18
19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21#include <linux/module.h>
22#include <linux/kernel.h>
23#include <linux/init.h>
24#include <linux/backlight.h>
25#include <linux/err.h>
26#include <linux/io.h>
27#include <linux/pci.h>
28#include <linux/acpi.h>
29#include <linux/atomic.h>
30#include <linux/apple_bl.h>
31
32static struct backlight_device *apple_backlight_device;
33
34struct hw_data {
35	/* I/O resource to allocate. */
36	unsigned long iostart;
37	unsigned long iolen;
38	/* Backlight operations structure. */
39	const struct backlight_ops backlight_ops;
40	void (*set_brightness)(int);
41};
42
43static const struct hw_data *hw_data;
44
45/* Module parameters. */
46static int debug;
47module_param_named(debug, debug, int, 0644);
48MODULE_PARM_DESC(debug, "Set to one to enable debugging messages.");
49
50/*
51 * Implementation for machines with Intel chipset.
52 */
53static void intel_chipset_set_brightness(int intensity)
54{
55	outb(0x04 | (intensity << 4), 0xb3);
56	outb(0xbf, 0xb2);
57}
58
59static int intel_chipset_send_intensity(struct backlight_device *bd)
60{
61	int intensity = bd->props.brightness;
62
63	if (debug)
64		pr_debug("setting brightness to %d\n", intensity);
65
66	intel_chipset_set_brightness(intensity);
67	return 0;
68}
69
70static int intel_chipset_get_intensity(struct backlight_device *bd)
71{
72	int intensity;
73
74	outb(0x03, 0xb3);
75	outb(0xbf, 0xb2);
76	intensity = inb(0xb3) >> 4;
77
78	if (debug)
79		pr_debug("read brightness of %d\n", intensity);
80
81	return intensity;
82}
83
84static const struct hw_data intel_chipset_data = {
85	.iostart = 0xb2,
86	.iolen = 2,
87	.backlight_ops	= {
88		.options	= BL_CORE_SUSPENDRESUME,
89		.get_brightness	= intel_chipset_get_intensity,
90		.update_status	= intel_chipset_send_intensity,
91	},
92	.set_brightness = intel_chipset_set_brightness,
93};
94
95/*
96 * Implementation for machines with Nvidia chipset.
97 */
98static void nvidia_chipset_set_brightness(int intensity)
99{
100	outb(0x04 | (intensity << 4), 0x52f);
101	outb(0xbf, 0x52e);
102}
103
104static int nvidia_chipset_send_intensity(struct backlight_device *bd)
105{
106	int intensity = bd->props.brightness;
107
108	if (debug)
109		pr_debug("setting brightness to %d\n", intensity);
110
111	nvidia_chipset_set_brightness(intensity);
112	return 0;
113}
114
115static int nvidia_chipset_get_intensity(struct backlight_device *bd)
116{
117	int intensity;
118
119	outb(0x03, 0x52f);
120	outb(0xbf, 0x52e);
121	intensity = inb(0x52f) >> 4;
122
123	if (debug)
124		pr_debug("read brightness of %d\n", intensity);
125
126	return intensity;
127}
128
129static const struct hw_data nvidia_chipset_data = {
130	.iostart = 0x52e,
131	.iolen = 2,
132	.backlight_ops		= {
133		.options	= BL_CORE_SUSPENDRESUME,
134		.get_brightness	= nvidia_chipset_get_intensity,
135		.update_status	= nvidia_chipset_send_intensity
136	},
137	.set_brightness = nvidia_chipset_set_brightness,
138};
139
140static int apple_bl_add(struct acpi_device *dev)
141{
142	struct backlight_properties props;
143	struct pci_dev *host;
144	int intensity;
145
146	host = pci_get_bus_and_slot(0, 0);
147
148	if (!host) {
149		pr_err("unable to find PCI host\n");
150		return -ENODEV;
151	}
152
153	if (host->vendor == PCI_VENDOR_ID_INTEL)
154		hw_data = &intel_chipset_data;
155	else if (host->vendor == PCI_VENDOR_ID_NVIDIA)
156		hw_data = &nvidia_chipset_data;
157
158	pci_dev_put(host);
159
160	if (!hw_data) {
161		pr_err("unknown hardware\n");
162		return -ENODEV;
163	}
164
165	/* Check that the hardware responds - this may not work under EFI */
166
167	intensity = hw_data->backlight_ops.get_brightness(NULL);
168
169	if (!intensity) {
170		hw_data->set_brightness(1);
171		if (!hw_data->backlight_ops.get_brightness(NULL))
172			return -ENODEV;
173
174		hw_data->set_brightness(0);
175	}
176
177	if (!request_region(hw_data->iostart, hw_data->iolen,
178			    "Apple backlight"))
179		return -ENXIO;
180
181	memset(&props, 0, sizeof(struct backlight_properties));
182	props.type = BACKLIGHT_PLATFORM;
183	props.max_brightness = 15;
184	apple_backlight_device = backlight_device_register("apple_backlight",
185				  NULL, NULL, &hw_data->backlight_ops, &props);
186
187	if (IS_ERR(apple_backlight_device)) {
188		release_region(hw_data->iostart, hw_data->iolen);
189		return PTR_ERR(apple_backlight_device);
190	}
191
192	apple_backlight_device->props.brightness =
193		hw_data->backlight_ops.get_brightness(apple_backlight_device);
194	backlight_update_status(apple_backlight_device);
195
196	return 0;
197}
198
199static int apple_bl_remove(struct acpi_device *dev)
200{
201	backlight_device_unregister(apple_backlight_device);
202
203	release_region(hw_data->iostart, hw_data->iolen);
204	hw_data = NULL;
205	return 0;
206}
207
208static const struct acpi_device_id apple_bl_ids[] = {
209	{"APP0002", 0},
210	{"", 0},
211};
212
213static struct acpi_driver apple_bl_driver = {
214	.name = "Apple backlight",
215	.ids = apple_bl_ids,
216	.ops = {
217		.add = apple_bl_add,
218		.remove = apple_bl_remove,
219	},
220};
221
222static atomic_t apple_bl_registered = ATOMIC_INIT(0);
223
224int apple_bl_register(void)
225{
226	if (atomic_xchg(&apple_bl_registered, 1) == 0)
227		return acpi_bus_register_driver(&apple_bl_driver);
228
229	return 0;
230}
231EXPORT_SYMBOL_GPL(apple_bl_register);
232
233void apple_bl_unregister(void)
234{
235	if (atomic_xchg(&apple_bl_registered, 0) == 1)
236		acpi_bus_unregister_driver(&apple_bl_driver);
237}
238EXPORT_SYMBOL_GPL(apple_bl_unregister);
239
240static int __init apple_bl_init(void)
241{
242	return apple_bl_register();
243}
244
245static void __exit apple_bl_exit(void)
246{
247	apple_bl_unregister();
248}
249
250module_init(apple_bl_init);
251module_exit(apple_bl_exit);
252
253MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
254MODULE_DESCRIPTION("Apple Backlight Driver");
255MODULE_LICENSE("GPL");
256MODULE_DEVICE_TABLE(acpi, apple_bl_ids);
257MODULE_ALIAS("mbp_nvidia_bl");
258