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