Merge branch 'for-linus' of git://oss.sgi.com/xfs/xfs
[linux-2.6] / arch / powerpc / platforms / powermac / backlight.c
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 <linux-kernel@hansmi.ch>
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 <asm/atomic.h>
16 #include <asm/prom.h>
17 #include <asm/backlight.h>
18
19 #define OLD_BACKLIGHT_MAX 15
20
21 static void pmac_backlight_key_worker(struct work_struct *work);
22 static void pmac_backlight_set_legacy_worker(struct work_struct *work);
23
24 static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker);
25 static DECLARE_WORK(pmac_backlight_set_legacy_work, pmac_backlight_set_legacy_worker);
26
27 /* Although these variables are used in interrupt context, it makes no sense to
28  * protect them. No user is able to produce enough key events per second and
29  * notice the errors that might happen.
30  */
31 static int pmac_backlight_key_queued;
32 static int pmac_backlight_set_legacy_queued;
33
34 /* The via-pmu code allows the backlight to be grabbed, in which case the
35  * in-kernel control of the brightness needs to be disabled. This should
36  * only be used by really old PowerBooks.
37  */
38 static atomic_t kernel_backlight_disabled = ATOMIC_INIT(0);
39
40 /* Protect the pmac_backlight variable below.
41    You should hold this lock when using the pmac_backlight pointer to
42    prevent its potential removal. */
43 DEFINE_MUTEX(pmac_backlight_mutex);
44
45 /* Main backlight storage
46  *
47  * Backlight drivers in this variable are required to have the "ops"
48  * attribute set and to have an update_status function.
49  *
50  * We can only store one backlight here, but since Apple laptops have only one
51  * internal display, it doesn't matter. Other backlight drivers can be used
52  * independently.
53  *
54  */
55 struct backlight_device *pmac_backlight;
56
57 int pmac_has_backlight_type(const char *type)
58 {
59         struct device_node* bk_node = of_find_node_by_name(NULL, "backlight");
60
61         if (bk_node) {
62                 const char *prop = of_get_property(bk_node,
63                                 "backlight-control", NULL);
64                 if (prop && strncmp(prop, type, strlen(type)) == 0) {
65                         of_node_put(bk_node);
66                         return 1;
67                 }
68                 of_node_put(bk_node);
69         }
70
71         return 0;
72 }
73
74 int pmac_backlight_curve_lookup(struct fb_info *info, int value)
75 {
76         int level = (FB_BACKLIGHT_LEVELS - 1);
77
78         if (info && info->bl_dev) {
79                 int i, max = 0;
80
81                 /* Look for biggest value */
82                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
83                         max = max((int)info->bl_curve[i], max);
84
85                 /* Look for nearest value */
86                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
87                         int diff = abs(info->bl_curve[i] - value);
88                         if (diff < max) {
89                                 max = diff;
90                                 level = i;
91                         }
92                 }
93
94         }
95
96         return level;
97 }
98
99 static void pmac_backlight_key_worker(struct work_struct *work)
100 {
101         if (atomic_read(&kernel_backlight_disabled))
102                 return;
103
104         mutex_lock(&pmac_backlight_mutex);
105         if (pmac_backlight) {
106                 struct backlight_properties *props;
107                 int brightness;
108
109                 props = &pmac_backlight->props;
110
111                 brightness = props->brightness +
112                         ((pmac_backlight_key_queued?-1:1) *
113                          (props->max_brightness / 15));
114
115                 if (brightness < 0)
116                         brightness = 0;
117                 else if (brightness > props->max_brightness)
118                         brightness = props->max_brightness;
119
120                 props->brightness = brightness;
121                 backlight_update_status(pmac_backlight);
122         }
123         mutex_unlock(&pmac_backlight_mutex);
124 }
125
126 /* This function is called in interrupt context */
127 void pmac_backlight_key(int direction)
128 {
129         if (atomic_read(&kernel_backlight_disabled))
130                 return;
131
132         /* we can receive multiple interrupts here, but the scheduled work
133          * will run only once, with the last value
134          */
135         pmac_backlight_key_queued = direction;
136         schedule_work(&pmac_backlight_key_work);
137 }
138
139 static int __pmac_backlight_set_legacy_brightness(int brightness)
140 {
141         int error = -ENXIO;
142
143         mutex_lock(&pmac_backlight_mutex);
144         if (pmac_backlight) {
145                 struct backlight_properties *props;
146
147                 props = &pmac_backlight->props;
148                 props->brightness = brightness *
149                         (props->max_brightness + 1) /
150                         (OLD_BACKLIGHT_MAX + 1);
151
152                 if (props->brightness > props->max_brightness)
153                         props->brightness = props->max_brightness;
154                 else if (props->brightness < 0)
155                         props->brightness = 0;
156
157                 backlight_update_status(pmac_backlight);
158
159                 error = 0;
160         }
161         mutex_unlock(&pmac_backlight_mutex);
162
163         return error;
164 }
165
166 static void pmac_backlight_set_legacy_worker(struct work_struct *work)
167 {
168         if (atomic_read(&kernel_backlight_disabled))
169                 return;
170
171         __pmac_backlight_set_legacy_brightness(pmac_backlight_set_legacy_queued);
172 }
173
174 /* This function is called in interrupt context */
175 void pmac_backlight_set_legacy_brightness_pmu(int brightness) {
176         if (atomic_read(&kernel_backlight_disabled))
177                 return;
178
179         pmac_backlight_set_legacy_queued = brightness;
180         schedule_work(&pmac_backlight_set_legacy_work);
181 }
182
183 int pmac_backlight_set_legacy_brightness(int brightness)
184 {
185         return __pmac_backlight_set_legacy_brightness(brightness);
186 }
187
188 int pmac_backlight_get_legacy_brightness()
189 {
190         int result = -ENXIO;
191
192         mutex_lock(&pmac_backlight_mutex);
193         if (pmac_backlight) {
194                 struct backlight_properties *props;
195
196                 props = &pmac_backlight->props;
197
198                 result = props->brightness *
199                         (OLD_BACKLIGHT_MAX + 1) /
200                         (props->max_brightness + 1);
201         }
202         mutex_unlock(&pmac_backlight_mutex);
203
204         return result;
205 }
206
207 void pmac_backlight_disable()
208 {
209         atomic_inc(&kernel_backlight_disabled);
210 }
211
212 void pmac_backlight_enable()
213 {
214         atomic_dec(&kernel_backlight_disabled);
215 }
216
217 EXPORT_SYMBOL_GPL(pmac_backlight);
218 EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
219 EXPORT_SYMBOL_GPL(pmac_has_backlight_type);