aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/video/backlight/backlight.c
blob: 9d5015e99372c4d0f9f6c67fa95f39f9d460eb85 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
/*
 * Backlight Lowlevel Control Abstraction
 *
 * Copyright (C) 2003,2004 Hewlett-Packard Company
 *
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/backlight.h>
#include <linux/notifier.h>
#include <linux/ctype.h>
#include <linux/err.h>
#include <linux/fb.h>
#include <asm/bug.h>

static ssize_t backlight_show_power(struct class_device *cdev, char *buf)
{
	int rc;
	struct backlight_device *bd = to_backlight_device(cdev);

	down(&bd->sem);
	if (likely(bd->props && bd->props->get_power))
		rc = sprintf(buf, "%d\n", bd->props->get_power(bd));
	else
		rc = -ENXIO;
	up(&bd->sem);

	return rc;
}

static ssize_t backlight_store_power(struct class_device *cdev, const char *buf, size_t count)
{
	int rc, power;
	char *endp;
	struct backlight_device *bd = to_backlight_device(cdev);

	power = simple_strtoul(buf, &endp, 0);
	if (*endp && !isspace(*endp))
		return -EINVAL;

	down(&bd->sem);
	if (likely(bd->props && bd->props->set_power)) {
		pr_debug("backlight: set power to %d\n", power);
		bd->props->set_power(bd, power);
		rc = count;
	} else
		rc = -ENXIO;
	up(&bd->sem);

	return rc;
}

static ssize_t backlight_show_brightness(struct class_device *cdev, char *buf)
{
	int rc;
	struct backlight_device *bd = to_backlight_device(cdev);

	down(&bd->sem);
	if (likely(bd->props && bd->props->get_brightness))
		rc = sprintf(buf, "%d\n", bd->props->get_brightness(bd));
	else
		rc = -ENXIO;
	up(&bd->sem);

	return rc;
}

static ssize_t backlight_store_brightness(struct class_device *cdev, const char *buf, size_t count)
{
	int rc, brightness;
	char *endp;
	struct backlight_device *bd = to_backlight_device(cdev);

	brightness = simple_strtoul(buf, &endp, 0);
	if (*endp && !isspace(*endp))
		return -EINVAL;

	down(&bd->sem);
	if (likely(bd->props && bd->props->set_brightness)) {
		pr_debug("backlight: set brightness to %d\n", brightness);
		bd->props->set_brightness(bd, brightness);
		rc = count;
	} else
		rc = -ENXIO;
	up(&bd->sem);

	return rc;
}

static ssize_t backlight_show_max_brightness(struct class_device *cdev, char *buf)
{
	int rc;
	struct backlight_device *bd = to_backlight_device(cdev);

	down(&bd->sem);
	if (likely(bd->props))
		rc = sprintf(buf, "%d\n", bd->props->max_brightness);
	else
		rc = -ENXIO;
	up(&bd->sem);

	return rc;
}

static void backlight_class_release(struct class_device *dev)
{
	struct backlight_device *bd = to_backlight_device(dev);
	kfree(bd);
}

static struct class backlight_class = {
	.name = "backlight",
	.release = backlight_class_release,
};

#define DECLARE_ATTR(_name,_mode,_show,_store)			\
{							 	\
	.attr	= { .name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE },	\
	.show	= _show,					\
	.store	= _store,					\
}

static struct class_device_attribute bl_class_device_attributes[] = {
	DECLARE_ATTR(power, 0644, backlight_show_power, backlight_store_power),
	DECLARE_ATTR(brightness, 0644, backlight_show_brightness, backlight_store_brightness),
	DECLARE_ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
};

/* This callback gets called when something important happens inside a
 * framebuffer driver. We're looking if that important event is blanking,
 * and if it is, we're switching backlight power as well ...
 */
static int fb_notifier_callback(struct notifier_block *self,
				unsigned long event, void *data)
{
	struct backlight_device *bd;
	struct fb_event *evdata =(struct fb_event *)data;

	/* If we aren't interested in this event, skip it immediately ... */
	if (event != FB_EVENT_BLANK)
		return 0;

	bd = container_of(self, struct backlight_device, fb_notif);
	down(&bd->sem);
	if (bd->props)
		if (!bd->props->check_fb || bd->props->check_fb(evdata->info))
			bd->props->set_power(bd, *(int *)evdata->data);
	up(&bd->sem);
	return 0;
}

/**
 * backlight_device_register - create and register a new object of
 *   backlight_device class.
 * @name: the name of the new object(must be the same as the name of the
 *   respective framebuffer device).
 * @devdata: an optional pointer to be stored in the class_device. The
 *   methods may retrieve it by using class_get_devdata(&bd->class_dev).
 * @bp: the backlight properties structure.
 *
 * Creates and registers new backlight class_device. Returns either an
 * ERR_PTR() or a pointer to the newly allocated device.
 */
struct backlight_device *backlight_device_register(const char *name, void *devdata,
						   struct backlight_properties *bp)
{
	int i, rc;
	struct backlight_device *new_bd;

	pr_debug("backlight_device_alloc: name=%s\n", name);

	new_bd = kmalloc(sizeof(struct backlight_device), GFP_KERNEL);
	if (unlikely(!new_bd))
		return ERR_PTR(ENOMEM);

	init_MUTEX(&new_bd->sem);
	new_bd->props = bp;
	memset(&new_bd->class_dev, 0, sizeof(new_bd->class_dev));
	new_bd->class_dev.class = &backlight_class;
	strlcpy(new_bd->class_dev.class_id, name, KOBJ_NAME_LEN);
	class_set_devdata(&new_bd->class_dev, devdata);

	rc = class_device_register(&new_bd->class_dev);
	if (unlikely(rc)) {
error:		kfree(new_bd);
		return ERR_PTR(rc);
	}

	memset(&new_bd->fb_notif, 0, sizeof(new_bd->fb_notif));
	new_bd->fb_notif.notifier_call = fb_notifier_callback;

	rc = fb_register_client(&new_bd->fb_notif);
	if (unlikely(rc))
		goto error;

	for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++) {
		rc = class_device_create_file(&new_bd->class_dev,
					      &bl_class_device_attributes[i]);
		if (unlikely(rc)) {
			while (--i >= 0)
				class_device_remove_file(&new_bd->class_dev,
							 &bl_class_device_attributes[i]);
			class_device_unregister(&new_bd->class_dev);
			/* No need to kfree(new_bd) since release() method was called */
			return ERR_PTR(rc);
		}
	}

	return new_bd;
}
EXPORT_SYMBOL(backlight_device_register);

/**
 * backlight_device_unregister - unregisters a backlight device object.
 * @bd: the backlight device object to be unregistered and freed.
 *
 * Unregisters a previously registered via backlight_device_register object.
 */
void backlight_device_unregister(struct backlight_device *bd)
{
	int i;

	if (!bd)
		return;

	pr_debug("backlight_device_unregister: name=%s\n", bd->class_dev.class_id);

	for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++)
		class_device_remove_file(&bd->class_dev,
					 &bl_class_device_attributes[i]);

	down(&bd->sem);
	bd->props = NULL;
	up(&bd->sem);

	fb_unregister_client(&bd->fb_notif);

	class_device_unregister(&bd->class_dev);
}
EXPORT_SYMBOL(backlight_device_unregister);

static void __exit backlight_class_exit(void)
{
	class_unregister(&backlight_class);
}

static int __init backlight_class_init(void)
{
	return class_register(&backlight_class);
}

/*
 * if this is compiled into the kernel, we need to ensure that the
 * class is registered before users of the class try to register lcd's
 */
postcore_initcall(backlight_class_init);
module_exit(backlight_class_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");