Linux Kernel  3.7.1
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backlight.c
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1 /*
2  * Miscellaneous procedures for dealing with the PowerMac hardware.
3  * Contains support for the backlight.
4  *
5  * Copyright (C) 2000 Benjamin Herrenschmidt
6  * Copyright (C) 2006 Michael Hanselmann <[email protected]>
7  *
8  */
9 
10 #include <linux/kernel.h>
11 #include <linux/fb.h>
12 #include <linux/backlight.h>
13 #include <linux/adb.h>
14 #include <linux/pmu.h>
15 #include <linux/atomic.h>
16 #include <linux/export.h>
17 #include <asm/prom.h>
18 #include <asm/backlight.h>
19 
20 #define OLD_BACKLIGHT_MAX 15
21 
22 static void pmac_backlight_key_worker(struct work_struct *work);
23 static void pmac_backlight_set_legacy_worker(struct work_struct *work);
24 
25 static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker);
26 static DECLARE_WORK(pmac_backlight_set_legacy_work, pmac_backlight_set_legacy_worker);
27 
28 /* Although these variables are used in interrupt context, it makes no sense to
29  * protect them. No user is able to produce enough key events per second and
30  * notice the errors that might happen.
31  */
32 static int pmac_backlight_key_queued;
33 static int pmac_backlight_set_legacy_queued;
34 
35 /* The via-pmu code allows the backlight to be grabbed, in which case the
36  * in-kernel control of the brightness needs to be disabled. This should
37  * only be used by really old PowerBooks.
38  */
39 static atomic_t kernel_backlight_disabled = ATOMIC_INIT(0);
40 
41 /* Protect the pmac_backlight variable below.
42  You should hold this lock when using the pmac_backlight pointer to
43  prevent its potential removal. */
44 DEFINE_MUTEX(pmac_backlight_mutex);
45 
46 /* Main backlight storage
47  *
48  * Backlight drivers in this variable are required to have the "ops"
49  * attribute set and to have an update_status function.
50  *
51  * We can only store one backlight here, but since Apple laptops have only one
52  * internal display, it doesn't matter. Other backlight drivers can be used
53  * independently.
54  *
55  */
57 
58 int pmac_has_backlight_type(const char *type)
59 {
60  struct device_node* bk_node = of_find_node_by_name(NULL, "backlight");
61 
62  if (bk_node) {
63  const char *prop = of_get_property(bk_node,
64  "backlight-control", NULL);
65  if (prop && strncmp(prop, type, strlen(type)) == 0) {
66  of_node_put(bk_node);
67  return 1;
68  }
69  of_node_put(bk_node);
70  }
71 
72  return 0;
73 }
74 
76 {
77  int level = (FB_BACKLIGHT_LEVELS - 1);
78 
79  if (info && info->bl_dev) {
80  int i, max = 0;
81 
82  /* Look for biggest value */
83  for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
84  max = max((int)info->bl_curve[i], max);
85 
86  /* Look for nearest value */
87  for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
88  int diff = abs(info->bl_curve[i] - value);
89  if (diff < max) {
90  max = diff;
91  level = i;
92  }
93  }
94 
95  }
96 
97  return level;
98 }
99 
100 static void pmac_backlight_key_worker(struct work_struct *work)
101 {
102  if (atomic_read(&kernel_backlight_disabled))
103  return;
104 
105  mutex_lock(&pmac_backlight_mutex);
106  if (pmac_backlight) {
107  struct backlight_properties *props;
108  int brightness;
109 
110  props = &pmac_backlight->props;
111 
112  brightness = props->brightness +
113  ((pmac_backlight_key_queued?-1:1) *
114  (props->max_brightness / 15));
115 
116  if (brightness < 0)
117  brightness = 0;
118  else if (brightness > props->max_brightness)
119  brightness = props->max_brightness;
120 
121  props->brightness = brightness;
122  backlight_update_status(pmac_backlight);
123  }
124  mutex_unlock(&pmac_backlight_mutex);
125 }
126 
127 /* This function is called in interrupt context */
129 {
130  if (atomic_read(&kernel_backlight_disabled))
131  return;
132 
133  /* we can receive multiple interrupts here, but the scheduled work
134  * will run only once, with the last value
135  */
136  pmac_backlight_key_queued = direction;
137  schedule_work(&pmac_backlight_key_work);
138 }
139 
140 static int __pmac_backlight_set_legacy_brightness(int brightness)
141 {
142  int error = -ENXIO;
143 
144  mutex_lock(&pmac_backlight_mutex);
145  if (pmac_backlight) {
146  struct backlight_properties *props;
147 
148  props = &pmac_backlight->props;
149  props->brightness = brightness *
150  (props->max_brightness + 1) /
151  (OLD_BACKLIGHT_MAX + 1);
152 
153  if (props->brightness > props->max_brightness)
154  props->brightness = props->max_brightness;
155  else if (props->brightness < 0)
156  props->brightness = 0;
157 
158  backlight_update_status(pmac_backlight);
159 
160  error = 0;
161  }
162  mutex_unlock(&pmac_backlight_mutex);
163 
164  return error;
165 }
166 
167 static void pmac_backlight_set_legacy_worker(struct work_struct *work)
168 {
169  if (atomic_read(&kernel_backlight_disabled))
170  return;
171 
172  __pmac_backlight_set_legacy_brightness(pmac_backlight_set_legacy_queued);
173 }
174 
175 /* This function is called in interrupt context */
177  if (atomic_read(&kernel_backlight_disabled))
178  return;
179 
180  pmac_backlight_set_legacy_queued = brightness;
181  schedule_work(&pmac_backlight_set_legacy_work);
182 }
183 
185 {
186  return __pmac_backlight_set_legacy_brightness(brightness);
187 }
188 
190 {
191  int result = -ENXIO;
192 
193  mutex_lock(&pmac_backlight_mutex);
194  if (pmac_backlight) {
195  struct backlight_properties *props;
196 
197  props = &pmac_backlight->props;
198 
199  result = props->brightness *
200  (OLD_BACKLIGHT_MAX + 1) /
201  (props->max_brightness + 1);
202  }
203  mutex_unlock(&pmac_backlight_mutex);
204 
205  return result;
206 }
207 
209 {
210  atomic_inc(&kernel_backlight_disabled);
211 }
212 
214 {
215  atomic_dec(&kernel_backlight_disabled);
216 }
217 
218 EXPORT_SYMBOL_GPL(pmac_backlight);
219 EXPORT_SYMBOL_GPL(pmac_backlight_mutex);