Merge master.kernel.org:/pub/scm/linux/kernel/git/perex/alsa
[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/config.h>
11 #include <linux/kernel.h>
12 #include <linux/fb.h>
13 #include <linux/backlight.h>
14 #include <asm/prom.h>
15 #include <asm/backlight.h>
16
17 #define OLD_BACKLIGHT_MAX 15
18
19 /* Protect the pmac_backlight variable */
20 DEFINE_MUTEX(pmac_backlight_mutex);
21
22 /* Main backlight storage
23  *
24  * Backlight drivers in this variable are required to have the "props"
25  * attribute set and to have an update_status function.
26  *
27  * We can only store one backlight here, but since Apple laptops have only one
28  * internal display, it doesn't matter. Other backlight drivers can be used
29  * independently.
30  *
31  * Lock ordering:
32  * pmac_backlight_mutex (global, main backlight)
33  *   pmac_backlight->sem (backlight class)
34  */
35 struct backlight_device *pmac_backlight;
36
37 int pmac_has_backlight_type(const char *type)
38 {
39         struct device_node* bk_node = find_devices("backlight");
40
41         if (bk_node) {
42                 char *prop = get_property(bk_node, "backlight-control", NULL);
43                 if (prop && strncmp(prop, type, strlen(type)) == 0)
44                         return 1;
45         }
46
47         return 0;
48 }
49
50 int pmac_backlight_curve_lookup(struct fb_info *info, int value)
51 {
52         int level = (FB_BACKLIGHT_LEVELS - 1);
53
54         if (info && info->bl_dev) {
55                 int i, max = 0;
56
57                 /* Look for biggest value */
58                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
59                         max = max((int)info->bl_curve[i], max);
60
61                 /* Look for nearest value */
62                 for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
63                         int diff = abs(info->bl_curve[i] - value);
64                         if (diff < max) {
65                                 max = diff;
66                                 level = i;
67                         }
68                 }
69
70         }
71
72         return level;
73 }
74
75 static void pmac_backlight_key(int direction)
76 {
77         mutex_lock(&pmac_backlight_mutex);
78         if (pmac_backlight) {
79                 struct backlight_properties *props;
80                 int brightness;
81
82                 down(&pmac_backlight->sem);
83                 props = pmac_backlight->props;
84
85                 brightness = props->brightness +
86                         ((direction?-1:1) * (props->max_brightness / 15));
87
88                 if (brightness < 0)
89                         brightness = 0;
90                 else if (brightness > props->max_brightness)
91                         brightness = props->max_brightness;
92
93                 props->brightness = brightness;
94                 props->update_status(pmac_backlight);
95
96                 up(&pmac_backlight->sem);
97         }
98         mutex_unlock(&pmac_backlight_mutex);
99 }
100
101 void pmac_backlight_key_up()
102 {
103         pmac_backlight_key(0);
104 }
105
106 void pmac_backlight_key_down()
107 {
108         pmac_backlight_key(1);
109 }
110
111 int pmac_backlight_set_legacy_brightness(int brightness)
112 {
113         int error = -ENXIO;
114
115         mutex_lock(&pmac_backlight_mutex);
116         if (pmac_backlight) {
117                 struct backlight_properties *props;
118
119                 down(&pmac_backlight->sem);
120                 props = pmac_backlight->props;
121                 props->brightness = brightness *
122                         (props->max_brightness + 1) /
123                         (OLD_BACKLIGHT_MAX + 1);
124
125                 if (props->brightness > props->max_brightness)
126                         props->brightness = props->max_brightness;
127                 else if (props->brightness < 0)
128                         props->brightness = 0;
129
130                 props->update_status(pmac_backlight);
131                 up(&pmac_backlight->sem);
132
133                 error = 0;
134         }
135         mutex_unlock(&pmac_backlight_mutex);
136
137         return error;
138 }
139
140 int pmac_backlight_get_legacy_brightness()
141 {
142         int result = -ENXIO;
143
144         mutex_lock(&pmac_backlight_mutex);
145         if (pmac_backlight) {
146                 struct backlight_properties *props;
147
148                 down(&pmac_backlight->sem);
149                 props = pmac_backlight->props;
150
151                 result = props->brightness *
152                         (OLD_BACKLIGHT_MAX + 1) /
153                         (props->max_brightness + 1);
154
155                 up(&pmac_backlight->sem);
156         }
157         mutex_unlock(&pmac_backlight_mutex);
158
159         return result;
160 }