[go: nahoru, domu]
1/*
2 * Driver for the Cirrus EP93xx lcd backlight
3 *
4 * Copyright (c) 2010 H Hartley Sweeten <hsweeten@visionengravers.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This driver controls the pulse width modulated brightness control output,
11 * BRIGHT, on the Cirrus EP9307, EP9312, and EP9315 processors.
12 */
13
14#include <linux/module.h>
15#include <linux/platform_device.h>
16#include <linux/io.h>
17#include <linux/fb.h>
18#include <linux/backlight.h>
19
20#define EP93XX_MAX_COUNT		255
21#define EP93XX_MAX_BRIGHT		255
22#define EP93XX_DEF_BRIGHT		128
23
24struct ep93xxbl {
25	void __iomem *mmio;
26	int brightness;
27};
28
29static int ep93xxbl_set(struct backlight_device *bl, int brightness)
30{
31	struct ep93xxbl *ep93xxbl = bl_get_data(bl);
32
33	writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio);
34
35	ep93xxbl->brightness = brightness;
36
37	return 0;
38}
39
40static int ep93xxbl_update_status(struct backlight_device *bl)
41{
42	int brightness = bl->props.brightness;
43
44	if (bl->props.power != FB_BLANK_UNBLANK ||
45	    bl->props.fb_blank != FB_BLANK_UNBLANK)
46		brightness = 0;
47
48	return ep93xxbl_set(bl, brightness);
49}
50
51static int ep93xxbl_get_brightness(struct backlight_device *bl)
52{
53	struct ep93xxbl *ep93xxbl = bl_get_data(bl);
54
55	return ep93xxbl->brightness;
56}
57
58static const struct backlight_ops ep93xxbl_ops = {
59	.update_status	= ep93xxbl_update_status,
60	.get_brightness	= ep93xxbl_get_brightness,
61};
62
63static int ep93xxbl_probe(struct platform_device *dev)
64{
65	struct ep93xxbl *ep93xxbl;
66	struct backlight_device *bl;
67	struct backlight_properties props;
68	struct resource *res;
69
70	ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL);
71	if (!ep93xxbl)
72		return -ENOMEM;
73
74	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
75	if (!res)
76		return -ENXIO;
77
78	/*
79	 * FIXME - We don't do a request_mem_region here because we are
80	 * sharing the register space with the framebuffer driver (see
81	 * drivers/video/ep93xx-fb.c) and doing so will cause the second
82	 * loaded driver to return -EBUSY.
83	 *
84	 * NOTE: No locking is required; the framebuffer does not touch
85	 * this register.
86	 */
87	ep93xxbl->mmio = devm_ioremap(&dev->dev, res->start,
88				      resource_size(res));
89	if (!ep93xxbl->mmio)
90		return -ENXIO;
91
92	memset(&props, 0, sizeof(struct backlight_properties));
93	props.type = BACKLIGHT_RAW;
94	props.max_brightness = EP93XX_MAX_BRIGHT;
95	bl = devm_backlight_device_register(&dev->dev, dev->name, &dev->dev,
96					ep93xxbl, &ep93xxbl_ops, &props);
97	if (IS_ERR(bl))
98		return PTR_ERR(bl);
99
100	bl->props.brightness = EP93XX_DEF_BRIGHT;
101
102	platform_set_drvdata(dev, bl);
103
104	ep93xxbl_update_status(bl);
105
106	return 0;
107}
108
109#ifdef CONFIG_PM_SLEEP
110static int ep93xxbl_suspend(struct device *dev)
111{
112	struct backlight_device *bl = dev_get_drvdata(dev);
113
114	return ep93xxbl_set(bl, 0);
115}
116
117static int ep93xxbl_resume(struct device *dev)
118{
119	struct backlight_device *bl = dev_get_drvdata(dev);
120
121	backlight_update_status(bl);
122	return 0;
123}
124#endif
125
126static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);
127
128static struct platform_driver ep93xxbl_driver = {
129	.driver		= {
130		.name	= "ep93xx-bl",
131		.pm	= &ep93xxbl_pm_ops,
132	},
133	.probe		= ep93xxbl_probe,
134};
135
136module_platform_driver(ep93xxbl_driver);
137
138MODULE_DESCRIPTION("EP93xx Backlight Driver");
139MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
140MODULE_LICENSE("GPL");
141MODULE_ALIAS("platform:ep93xx-bl");
142