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apple_bl.c
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1 /*
2  * Backlight Driver for Intel-based Apples
3  *
4  * Copyright (c) Red Hat <[email protected]>
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 <[email protected]>
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. */
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 __devinit 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 
199 static int __devexit apple_bl_remove(struct acpi_device *dev, int type)
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 
225 {
226  if (atomic_xchg(&apple_bl_registered, 1) == 0)
227  return acpi_bus_register_driver(&apple_bl_driver);
228 
229  return 0;
230 }
232 
234 {
235  if (atomic_xchg(&apple_bl_registered, 0) == 1)
236  acpi_bus_unregister_driver(&apple_bl_driver);
237 }
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 {
248 }
249 
250 module_init(apple_bl_init);
251 module_exit(apple_bl_exit);
252 
253 MODULE_AUTHOR("Matthew Garrett <[email protected]>");
254 MODULE_DESCRIPTION("Apple Backlight Driver");
255 MODULE_LICENSE("GPL");
256 MODULE_DEVICE_TABLE(acpi, apple_bl_ids);
257 MODULE_ALIAS("mbp_nvidia_bl");