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/kernel.h>
11#include <linux/fb.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/prom.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
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
75int 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
100static 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 */
128void 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
140static 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
167static 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 */
176void 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
184int pmac_backlight_set_legacy_brightness(int brightness)
185{
186	return __pmac_backlight_set_legacy_brightness(brightness);
187}
188
189int pmac_backlight_get_legacy_brightness()
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
208void pmac_backlight_disable()
209{
210	atomic_inc(&kernel_backlight_disabled);
211}
212
213void pmac_backlight_enable()
214{
215	atomic_dec(&kernel_backlight_disabled);
216}
217
218EXPORT_SYMBOL_GPL(pmac_backlight);
219EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
220EXPORT_SYMBOL_GPL(pmac_has_backlight_type);
221