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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/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
21static void pmac_backlight_key_worker(struct work_struct *work);
22static void pmac_backlight_set_legacy_worker(struct work_struct *work);
23
24static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker);
25static 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 */
31static int pmac_backlight_key_queued;
32static 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 */
38static 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. */
43DEFINE_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 */
55struct backlight_device *pmac_backlight;
56
57int pmac_has_backlight_type(const char *type)
58{
59 struct device_node* bk_node = of_find_node_by_name(NULL, "backlight");
60 int i = of_property_match_string(bk_node, "backlight-control", type);
61
62 of_node_put(bk_node);
63 return i >= 0;
64}
65
66static void pmac_backlight_key_worker(struct work_struct *work)
67{
68 if (atomic_read(&kernel_backlight_disabled))
69 return;
70
71 mutex_lock(&pmac_backlight_mutex);
72 if (pmac_backlight) {
73 struct backlight_properties *props;
74 int brightness;
75
76 props = &pmac_backlight->props;
77
78 brightness = props->brightness +
79 ((pmac_backlight_key_queued?-1:1) *
80 (props->max_brightness / 15));
81
82 if (brightness < 0)
83 brightness = 0;
84 else if (brightness > props->max_brightness)
85 brightness = props->max_brightness;
86
87 props->brightness = brightness;
88 backlight_update_status(pmac_backlight);
89 }
90 mutex_unlock(&pmac_backlight_mutex);
91}
92
93/* This function is called in interrupt context */
94void pmac_backlight_key(int direction)
95{
96 if (atomic_read(&kernel_backlight_disabled))
97 return;
98
99 /* we can receive multiple interrupts here, but the scheduled work
100 * will run only once, with the last value
101 */
102 pmac_backlight_key_queued = direction;
103 schedule_work(&pmac_backlight_key_work);
104}
105
106static int __pmac_backlight_set_legacy_brightness(int brightness)
107{
108 int error = -ENXIO;
109
110 mutex_lock(&pmac_backlight_mutex);
111 if (pmac_backlight) {
112 struct backlight_properties *props;
113
114 props = &pmac_backlight->props;
115 props->brightness = brightness *
116 (props->max_brightness + 1) /
117 (OLD_BACKLIGHT_MAX + 1);
118
119 if (props->brightness > props->max_brightness)
120 props->brightness = props->max_brightness;
121 else if (props->brightness < 0)
122 props->brightness = 0;
123
124 backlight_update_status(pmac_backlight);
125
126 error = 0;
127 }
128 mutex_unlock(&pmac_backlight_mutex);
129
130 return error;
131}
132
133static void pmac_backlight_set_legacy_worker(struct work_struct *work)
134{
135 if (atomic_read(&kernel_backlight_disabled))
136 return;
137
138 __pmac_backlight_set_legacy_brightness(pmac_backlight_set_legacy_queued);
139}
140
141/* This function is called in interrupt context */
142void pmac_backlight_set_legacy_brightness_pmu(int brightness) {
143 if (atomic_read(&kernel_backlight_disabled))
144 return;
145
146 pmac_backlight_set_legacy_queued = brightness;
147 schedule_work(&pmac_backlight_set_legacy_work);
148}
149
150int pmac_backlight_set_legacy_brightness(int brightness)
151{
152 return __pmac_backlight_set_legacy_brightness(brightness);
153}
154
155int pmac_backlight_get_legacy_brightness(void)
156{
157 int result = -ENXIO;
158
159 mutex_lock(&pmac_backlight_mutex);
160 if (pmac_backlight) {
161 struct backlight_properties *props;
162
163 props = &pmac_backlight->props;
164
165 result = props->brightness *
166 (OLD_BACKLIGHT_MAX + 1) /
167 (props->max_brightness + 1);
168 }
169 mutex_unlock(&pmac_backlight_mutex);
170
171 return result;
172}
173
174void pmac_backlight_disable(void)
175{
176 atomic_inc(&kernel_backlight_disabled);
177}
178
179void pmac_backlight_enable(void)
180{
181 atomic_dec(&kernel_backlight_disabled);
182}
183
184EXPORT_SYMBOL_GPL(pmac_backlight);
185EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
186EXPORT_SYMBOL_GPL(pmac_has_backlight_type);