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 #include <linux/module.h>
20 #include <linux/kernel.h>
21 #include <linux/init.h>
22 #include <linux/backlight.h>
23 #include <linux/err.h>
24 #include <linux/io.h>
25 #include <linux/pci.h>
26 #include <linux/acpi.h>
27 #include <linux/atomic.h>
28 #include <linux/apple_bl.h>
29 
30 static struct backlight_device *apple_backlight_device;
31 
32 struct hw_data {
33 	/* I/O resource to allocate. */
34 	unsigned long iostart;
35 	unsigned long iolen;
36 	/* Backlight operations structure. */
37 	const struct backlight_ops backlight_ops;
38 	void (*set_brightness)(int);
39 };
40 
41 static const struct hw_data *hw_data;
42 
43 #define DRIVER "apple_backlight: "
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 		printk(KERN_DEBUG DRIVER "setting brightness to %d\n",
65 		       intensity);
66 
67 	intel_chipset_set_brightness(intensity);
68 	return 0;
69 }
70 
71 static int intel_chipset_get_intensity(struct backlight_device *bd)
72 {
73 	int intensity;
74 
75 	outb(0x03, 0xb3);
76 	outb(0xbf, 0xb2);
77 	intensity = inb(0xb3) >> 4;
78 
79 	if (debug)
80 		printk(KERN_DEBUG DRIVER "read brightness of %d\n",
81 		       intensity);
82 
83 	return intensity;
84 }
85 
86 static const struct hw_data intel_chipset_data = {
87 	.iostart = 0xb2,
88 	.iolen = 2,
89 	.backlight_ops	= {
90 		.options	= BL_CORE_SUSPENDRESUME,
91 		.get_brightness	= intel_chipset_get_intensity,
92 		.update_status	= intel_chipset_send_intensity,
93 	},
94 	.set_brightness = intel_chipset_set_brightness,
95 };
96 
97 /*
98  * Implementation for machines with Nvidia chipset.
99  */
100 static void nvidia_chipset_set_brightness(int intensity)
101 {
102 	outb(0x04 | (intensity << 4), 0x52f);
103 	outb(0xbf, 0x52e);
104 }
105 
106 static int nvidia_chipset_send_intensity(struct backlight_device *bd)
107 {
108 	int intensity = bd->props.brightness;
109 
110 	if (debug)
111 		printk(KERN_DEBUG DRIVER "setting brightness to %d\n",
112 		       intensity);
113 
114 	nvidia_chipset_set_brightness(intensity);
115 	return 0;
116 }
117 
118 static int nvidia_chipset_get_intensity(struct backlight_device *bd)
119 {
120 	int intensity;
121 
122 	outb(0x03, 0x52f);
123 	outb(0xbf, 0x52e);
124 	intensity = inb(0x52f) >> 4;
125 
126 	if (debug)
127 		printk(KERN_DEBUG DRIVER "read brightness of %d\n",
128 		       intensity);
129 
130 	return intensity;
131 }
132 
133 static const struct hw_data nvidia_chipset_data = {
134 	.iostart = 0x52e,
135 	.iolen = 2,
136 	.backlight_ops		= {
137 		.options	= BL_CORE_SUSPENDRESUME,
138 		.get_brightness	= nvidia_chipset_get_intensity,
139 		.update_status	= nvidia_chipset_send_intensity
140 	},
141 	.set_brightness = nvidia_chipset_set_brightness,
142 };
143 
144 static int __devinit apple_bl_add(struct acpi_device *dev)
145 {
146 	struct backlight_properties props;
147 	struct pci_dev *host;
148 	int intensity;
149 
150 	host = pci_get_bus_and_slot(0, 0);
151 
152 	if (!host) {
153 		printk(KERN_ERR DRIVER "unable to find PCI host\n");
154 		return -ENODEV;
155 	}
156 
157 	if (host->vendor == PCI_VENDOR_ID_INTEL)
158 		hw_data = &intel_chipset_data;
159 	else if (host->vendor == PCI_VENDOR_ID_NVIDIA)
160 		hw_data = &nvidia_chipset_data;
161 
162 	pci_dev_put(host);
163 
164 	if (!hw_data) {
165 		printk(KERN_ERR DRIVER "unknown hardware\n");
166 		return -ENODEV;
167 	}
168 
169 	/* Check that the hardware responds - this may not work under EFI */
170 
171 	intensity = hw_data->backlight_ops.get_brightness(NULL);
172 
173 	if (!intensity) {
174 		hw_data->set_brightness(1);
175 		if (!hw_data->backlight_ops.get_brightness(NULL))
176 			return -ENODEV;
177 
178 		hw_data->set_brightness(0);
179 	}
180 
181 	if (!request_region(hw_data->iostart, hw_data->iolen,
182 			    "Apple backlight"))
183 		return -ENXIO;
184 
185 	memset(&props, 0, sizeof(struct backlight_properties));
186 	props.type = BACKLIGHT_PLATFORM;
187 	props.max_brightness = 15;
188 	apple_backlight_device = backlight_device_register("apple_backlight",
189 				  NULL, NULL, &hw_data->backlight_ops, &props);
190 
191 	if (IS_ERR(apple_backlight_device)) {
192 		release_region(hw_data->iostart, hw_data->iolen);
193 		return PTR_ERR(apple_backlight_device);
194 	}
195 
196 	apple_backlight_device->props.brightness =
197 		hw_data->backlight_ops.get_brightness(apple_backlight_device);
198 	backlight_update_status(apple_backlight_device);
199 
200 	return 0;
201 }
202 
203 static int __devexit apple_bl_remove(struct acpi_device *dev, int type)
204 {
205 	backlight_device_unregister(apple_backlight_device);
206 
207 	release_region(hw_data->iostart, hw_data->iolen);
208 	hw_data = NULL;
209 	return 0;
210 }
211 
212 static const struct acpi_device_id apple_bl_ids[] = {
213 	{"APP0002", 0},
214 	{"", 0},
215 };
216 
217 static struct acpi_driver apple_bl_driver = {
218 	.name = "Apple backlight",
219 	.ids = apple_bl_ids,
220 	.ops = {
221 		.add = apple_bl_add,
222 		.remove = apple_bl_remove,
223 	},
224 };
225 
226 static atomic_t apple_bl_registered = ATOMIC_INIT(0);
227 
228 int apple_bl_register(void)
229 {
230 	if (atomic_xchg(&apple_bl_registered, 1) == 0)
231 		return acpi_bus_register_driver(&apple_bl_driver);
232 
233 	return 0;
234 }
235 EXPORT_SYMBOL_GPL(apple_bl_register);
236 
237 void apple_bl_unregister(void)
238 {
239 	if (atomic_xchg(&apple_bl_registered, 0) == 1)
240 		acpi_bus_unregister_driver(&apple_bl_driver);
241 }
242 EXPORT_SYMBOL_GPL(apple_bl_unregister);
243 
244 static int __init apple_bl_init(void)
245 {
246 	return apple_bl_register();
247 }
248 
249 static void __exit apple_bl_exit(void)
250 {
251 	apple_bl_unregister();
252 }
253 
254 module_init(apple_bl_init);
255 module_exit(apple_bl_exit);
256 
257 MODULE_AUTHOR("Matthew Garrett <mjg@redhat.com>");
258 MODULE_DESCRIPTION("Apple Backlight Driver");
259 MODULE_LICENSE("GPL");
260 MODULE_DEVICE_TABLE(acpi, apple_bl_ids);
261 MODULE_ALIAS("mbp_nvidia_bl");
262