1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Miscellaneous procedures for dealing with the PowerMac hardware.
4 * Contains support for the backlight.
5 *
6 * Copyright (C) 2000 Benjamin Herrenschmidt
7 * Copyright (C) 2006 Michael Hanselmann <linux-kernel@hansmi.ch>
8 *
9 */
10
11 #include <linux/kernel.h>
12 #include <linux/fb.h>
13 #include <linux/backlight.h>
14 #include <linux/adb.h>
15 #include <linux/pmu.h>
16 #include <linux/atomic.h>
17 #include <linux/export.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 */
56 struct backlight_device *pmac_backlight;
57
pmac_has_backlight_type(const char * type)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
pmac_backlight_curve_lookup(struct fb_info * info,int value)75 int pmac_backlight_curve_lookup(struct fb_info *info, int value)
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
pmac_backlight_key_worker(struct work_struct * work)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 */
pmac_backlight_key(int direction)128 void pmac_backlight_key(int direction)
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
__pmac_backlight_set_legacy_brightness(int brightness)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
pmac_backlight_set_legacy_worker(struct work_struct * work)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 */
pmac_backlight_set_legacy_brightness_pmu(int brightness)176 void pmac_backlight_set_legacy_brightness_pmu(int brightness) {
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
pmac_backlight_set_legacy_brightness(int brightness)184 int pmac_backlight_set_legacy_brightness(int brightness)
185 {
186 return __pmac_backlight_set_legacy_brightness(brightness);
187 }
188
pmac_backlight_get_legacy_brightness(void)189 int pmac_backlight_get_legacy_brightness(void)
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
pmac_backlight_disable(void)208 void pmac_backlight_disable(void)
209 {
210 atomic_inc(&kernel_backlight_disabled);
211 }
212
pmac_backlight_enable(void)213 void pmac_backlight_enable(void)
214 {
215 atomic_dec(&kernel_backlight_disabled);
216 }
217
218 EXPORT_SYMBOL_GPL(pmac_backlight);
219 EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
220 EXPORT_SYMBOL_GPL(pmac_has_backlight_type);
221