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/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/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 static void pmac_backlight_key_worker(struct work_struct *work)
75 {
76 if (atomic_read(&kernel_backlight_disabled))
77 return;
78
79 mutex_lock(&pmac_backlight_mutex);
80 if (pmac_backlight) {
81 struct backlight_properties *props;
82 int brightness;
83
84 props = &pmac_backlight->props;
85
86 brightness = props->brightness +
87 ((pmac_backlight_key_queued?-1:1) *
88 (props->max_brightness / 15));
89
90 if (brightness < 0)
91 brightness = 0;
92 else if (brightness > props->max_brightness)
93 brightness = props->max_brightness;
94
95 props->brightness = brightness;
96 backlight_update_status(pmac_backlight);
97 }
98 mutex_unlock(&pmac_backlight_mutex);
99 }
100
101 /* This function is called in interrupt context */
102 void pmac_backlight_key(int direction)
103 {
104 if (atomic_read(&kernel_backlight_disabled))
105 return;
106
107 /* we can receive multiple interrupts here, but the scheduled work
108 * will run only once, with the last value
109 */
110 pmac_backlight_key_queued = direction;
111 schedule_work(&pmac_backlight_key_work);
112 }
113
114 static int __pmac_backlight_set_legacy_brightness(int brightness)
115 {
116 int error = -ENXIO;
117
118 mutex_lock(&pmac_backlight_mutex);
119 if (pmac_backlight) {
120 struct backlight_properties *props;
121
122 props = &pmac_backlight->props;
123 props->brightness = brightness *
124 (props->max_brightness + 1) /
125 (OLD_BACKLIGHT_MAX + 1);
126
127 if (props->brightness > props->max_brightness)
128 props->brightness = props->max_brightness;
129 else if (props->brightness < 0)
130 props->brightness = 0;
131
132 backlight_update_status(pmac_backlight);
133
134 error = 0;
135 }
136 mutex_unlock(&pmac_backlight_mutex);
137
138 return error;
139 }
140
141 static void pmac_backlight_set_legacy_worker(struct work_struct *work)
142 {
143 if (atomic_read(&kernel_backlight_disabled))
144 return;
145
146 __pmac_backlight_set_legacy_brightness(pmac_backlight_set_legacy_queued);
147 }
148
149 /* This function is called in interrupt context */
150 void pmac_backlight_set_legacy_brightness_pmu(int brightness) {
151 if (atomic_read(&kernel_backlight_disabled))
152 return;
153
154 pmac_backlight_set_legacy_queued = brightness;
155 schedule_work(&pmac_backlight_set_legacy_work);
156 }
157
158 int pmac_backlight_set_legacy_brightness(int brightness)
159 {
160 return __pmac_backlight_set_legacy_brightness(brightness);
161 }
162
163 int pmac_backlight_get_legacy_brightness(void)
164 {
165 int result = -ENXIO;
166
167 mutex_lock(&pmac_backlight_mutex);
168 if (pmac_backlight) {
169 struct backlight_properties *props;
170
171 props = &pmac_backlight->props;
172
173 result = props->brightness *
174 (OLD_BACKLIGHT_MAX + 1) /
175 (props->max_brightness + 1);
176 }
177 mutex_unlock(&pmac_backlight_mutex);
178
179 return result;
180 }
181
182 void pmac_backlight_disable(void)
183 {
184 atomic_inc(&kernel_backlight_disabled);
185 }
186
187 void pmac_backlight_enable(void)
188 {
189 atomic_dec(&kernel_backlight_disabled);
190 }
191
192 EXPORT_SYMBOL_GPL(pmac_backlight);
193 EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
194 EXPORT_SYMBOL_GPL(pmac_has_backlight_type);
195
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