tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
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linux
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Driver for the Cirrus EP93xx lcd backlight
4 *
5 * Copyright (c) 2010 H Hartley Sweeten <hsweeten@visionengravers.com>
6 *
7 * This driver controls the pulse width modulated brightness control output,
8 * BRIGHT, on the Cirrus EP9307, EP9312, and EP9315 processors.
9 */
10
11#include <linux/module.h>
12#include <linux/platform_device.h>
13#include <linux/io.h>
14#include <linux/fb.h>
15#include <linux/backlight.h>
16
17#define EP93XX_MAX_COUNT 255
18#define EP93XX_MAX_BRIGHT 255
19#define EP93XX_DEF_BRIGHT 128
20
21struct ep93xxbl {
22 void __iomem *mmio;
23 int brightness;
24};
25
26static int ep93xxbl_set(struct backlight_device *bl, int brightness)
27{
28 struct ep93xxbl *ep93xxbl = bl_get_data(bl);
29
30 writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio);
31
32 ep93xxbl->brightness = brightness;
33
34 return 0;
35}
36
37static int ep93xxbl_update_status(struct backlight_device *bl)
38{
39 int brightness = bl->props.brightness;
40
41 if (bl->props.power != FB_BLANK_UNBLANK ||
42 bl->props.fb_blank != FB_BLANK_UNBLANK)
43 brightness = 0;
44
45 return ep93xxbl_set(bl, brightness);
46}
47
48static int ep93xxbl_get_brightness(struct backlight_device *bl)
49{
50 struct ep93xxbl *ep93xxbl = bl_get_data(bl);
51
52 return ep93xxbl->brightness;
53}
54
55static const struct backlight_ops ep93xxbl_ops = {
56 .update_status = ep93xxbl_update_status,
57 .get_brightness = ep93xxbl_get_brightness,
58};
59
60static int ep93xxbl_probe(struct platform_device *dev)
61{
62 struct ep93xxbl *ep93xxbl;
63 struct backlight_device *bl;
64 struct backlight_properties props;
65 struct resource *res;
66
67 ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL);
68 if (!ep93xxbl)
69 return -ENOMEM;
70
71 res = platform_get_resource(dev, IORESOURCE_MEM, 0);
72 if (!res)
73 return -ENXIO;
74
75 /*
76 * FIXME - We don't do a request_mem_region here because we are
77 * sharing the register space with the framebuffer driver (see
78 * drivers/video/ep93xx-fb.c) and doing so will cause the second
79 * loaded driver to return -EBUSY.
80 *
81 * NOTE: No locking is required; the framebuffer does not touch
82 * this register.
83 */
84 ep93xxbl->mmio = devm_ioremap(&dev->dev, res->start,
85 resource_size(res));
86 if (!ep93xxbl->mmio)
87 return -ENXIO;
88
89 memset(&props, 0, sizeof(struct backlight_properties));
90 props.type = BACKLIGHT_RAW;
91 props.max_brightness = EP93XX_MAX_BRIGHT;
92 bl = devm_backlight_device_register(&dev->dev, dev->name, &dev->dev,
93 ep93xxbl, &ep93xxbl_ops, &props);
94 if (IS_ERR(bl))
95 return PTR_ERR(bl);
96
97 bl->props.brightness = EP93XX_DEF_BRIGHT;
98
99 platform_set_drvdata(dev, bl);
100
101 ep93xxbl_update_status(bl);
102
103 return 0;
104}
105
106#ifdef CONFIG_PM_SLEEP
107static int ep93xxbl_suspend(struct device *dev)
108{
109 struct backlight_device *bl = dev_get_drvdata(dev);
110
111 return ep93xxbl_set(bl, 0);
112}
113
114static int ep93xxbl_resume(struct device *dev)
115{
116 struct backlight_device *bl = dev_get_drvdata(dev);
117
118 backlight_update_status(bl);
119 return 0;
120}
121#endif
122
123static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);
124
125static struct platform_driver ep93xxbl_driver = {
126 .driver = {
127 .name = "ep93xx-bl",
128 .pm = &ep93xxbl_pm_ops,
129 },
130 .probe = ep93xxbl_probe,
131};
132
133module_platform_driver(ep93xxbl_driver);
134
135MODULE_DESCRIPTION("EP93xx Backlight Driver");
136MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
137MODULE_LICENSE("GPL");
138MODULE_ALIAS("platform:ep93xx-bl");