Linux kernel mirror (for testing)
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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/of.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
22static void pmac_backlight_key_worker(struct work_struct *work);
23static void pmac_backlight_set_legacy_worker(struct work_struct *work);
24
25static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker);
26static 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 */
32static int pmac_backlight_key_queued;
33static 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 */
39static 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. */
44DEFINE_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 */
56struct backlight_device *pmac_backlight;
57
58int pmac_has_backlight_type(const char *type)
59{
60 struct device_node* bk_node = of_find_node_by_name(NULL, "backlight");
61 int i = of_property_match_string(bk_node, "backlight-control", type);
62
63 of_node_put(bk_node);
64 return i >= 0;
65}
66
67static void pmac_backlight_key_worker(struct work_struct *work)
68{
69 if (atomic_read(&kernel_backlight_disabled))
70 return;
71
72 mutex_lock(&pmac_backlight_mutex);
73 if (pmac_backlight) {
74 struct backlight_properties *props;
75 int brightness;
76
77 props = &pmac_backlight->props;
78
79 brightness = props->brightness +
80 ((pmac_backlight_key_queued?-1:1) *
81 (props->max_brightness / 15));
82
83 if (brightness < 0)
84 brightness = 0;
85 else if (brightness > props->max_brightness)
86 brightness = props->max_brightness;
87
88 props->brightness = brightness;
89 backlight_update_status(pmac_backlight);
90 }
91 mutex_unlock(&pmac_backlight_mutex);
92}
93
94/* This function is called in interrupt context */
95void pmac_backlight_key(int direction)
96{
97 if (atomic_read(&kernel_backlight_disabled))
98 return;
99
100 /* we can receive multiple interrupts here, but the scheduled work
101 * will run only once, with the last value
102 */
103 pmac_backlight_key_queued = direction;
104 schedule_work(&pmac_backlight_key_work);
105}
106
107static int __pmac_backlight_set_legacy_brightness(int brightness)
108{
109 int error = -ENXIO;
110
111 mutex_lock(&pmac_backlight_mutex);
112 if (pmac_backlight) {
113 struct backlight_properties *props;
114
115 props = &pmac_backlight->props;
116 props->brightness = brightness *
117 (props->max_brightness + 1) /
118 (OLD_BACKLIGHT_MAX + 1);
119
120 if (props->brightness > props->max_brightness)
121 props->brightness = props->max_brightness;
122 else if (props->brightness < 0)
123 props->brightness = 0;
124
125 backlight_update_status(pmac_backlight);
126
127 error = 0;
128 }
129 mutex_unlock(&pmac_backlight_mutex);
130
131 return error;
132}
133
134static void pmac_backlight_set_legacy_worker(struct work_struct *work)
135{
136 if (atomic_read(&kernel_backlight_disabled))
137 return;
138
139 __pmac_backlight_set_legacy_brightness(pmac_backlight_set_legacy_queued);
140}
141
142/* This function is called in interrupt context */
143void pmac_backlight_set_legacy_brightness_pmu(int brightness) {
144 if (atomic_read(&kernel_backlight_disabled))
145 return;
146
147 pmac_backlight_set_legacy_queued = brightness;
148 schedule_work(&pmac_backlight_set_legacy_work);
149}
150
151int pmac_backlight_set_legacy_brightness(int brightness)
152{
153 return __pmac_backlight_set_legacy_brightness(brightness);
154}
155
156int pmac_backlight_get_legacy_brightness(void)
157{
158 int result = -ENXIO;
159
160 mutex_lock(&pmac_backlight_mutex);
161 if (pmac_backlight) {
162 struct backlight_properties *props;
163
164 props = &pmac_backlight->props;
165
166 result = props->brightness *
167 (OLD_BACKLIGHT_MAX + 1) /
168 (props->max_brightness + 1);
169 }
170 mutex_unlock(&pmac_backlight_mutex);
171
172 return result;
173}
174
175void pmac_backlight_disable(void)
176{
177 atomic_inc(&kernel_backlight_disabled);
178}
179
180void pmac_backlight_enable(void)
181{
182 atomic_dec(&kernel_backlight_disabled);
183}
184
185EXPORT_SYMBOL_GPL(pmac_backlight);
186EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
187EXPORT_SYMBOL_GPL(pmac_has_backlight_type);