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 
32 static struct backlight_device *apple_backlight_device;
33 
34 struct 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 
43 static const struct hw_data *hw_data;
44 
45 /* Module parameters. */
46 static int debug;
47 module_param_named(debug, debug, int, 0644);
48 MODULE_PARM_DESC(debug, "Set to one to enable debugging messages.");
49 
50 /*
51  * Implementation for machines with Intel chipset.
52  */
53 static void intel_chipset_set_brightness(int intensity)
54 {
55 	outb(0x04 | (intensity << 4), 0xb3);
56 	outb(0xbf, 0xb2);
57 }
58 
59 static 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 
70 static 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 
84 static 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  */
98 static void nvidia_chipset_set_brightness(int intensity)
99 {
100 	outb(0x04 | (intensity << 4), 0x52f);
101 	outb(0xbf, 0x52e);
102 }
103 
104 static 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 
115 static 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 
129 static 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 
140 static 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_domain_bus_and_slot(0, 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 
199 static 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 
208 static const struct acpi_device_id apple_bl_ids[] = {
209 	{"APP0002", 0},
210 	{"", 0},
211 };
212 
213 static 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 
222 static atomic_t apple_bl_registered = ATOMIC_INIT(0);
223 
224 int 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 }
231 EXPORT_SYMBOL_GPL(apple_bl_register);
232 
233 void apple_bl_unregister(void)
234 {
235 	if (atomic_xchg(&apple_bl_registered, 0) == 1)
236 		acpi_bus_unregister_driver(&apple_bl_driver);
237 }
238 EXPORT_SYMBOL_GPL(apple_bl_unregister);
239 
240 static int __init apple_bl_init(void)
241 {
242 	return apple_bl_register();
243 }
244 
245 static void __exit apple_bl_exit(void)
246 {
247 	apple_bl_unregister();
248 }
249 
250 module_init(apple_bl_init);
251 module_exit(apple_bl_exit);
252 
253 MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
254 MODULE_DESCRIPTION("Apple Backlight Driver");
255 MODULE_LICENSE("GPL");
256 MODULE_DEVICE_TABLE(acpi, apple_bl_ids);
257 MODULE_ALIAS("mbp_nvidia_bl");
258