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	return ep93xxbl_set(bl, backlight_get_brightness(bl));
40}
41
42static int ep93xxbl_get_brightness(struct backlight_device *bl)
43{
44	struct ep93xxbl *ep93xxbl = bl_get_data(bl);
45
46	return ep93xxbl->brightness;
47}
48
49static const struct backlight_ops ep93xxbl_ops = {
50	.update_status	= ep93xxbl_update_status,
51	.get_brightness	= ep93xxbl_get_brightness,
52};
53
54static int ep93xxbl_probe(struct platform_device *dev)
55{
56	struct ep93xxbl *ep93xxbl;
57	struct backlight_device *bl;
58	struct backlight_properties props;
59	struct resource *res;
60
61	ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL);
62	if (!ep93xxbl)
63		return -ENOMEM;
64
65	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
66	if (!res)
67		return -ENXIO;
68
69	/*
70	 * FIXME - We don't do a request_mem_region here because we are
71	 * sharing the register space with the framebuffer driver (see
72	 * drivers/video/ep93xx-fb.c) and doing so will cause the second
73	 * loaded driver to return -EBUSY.
74	 *
75	 * NOTE: No locking is required; the framebuffer does not touch
76	 * this register.
77	 */
78	ep93xxbl->mmio = devm_ioremap(&dev->dev, res->start,
79				      resource_size(res));
80	if (!ep93xxbl->mmio)
81		return -ENXIO;
82
83	memset(&props, 0, sizeof(struct backlight_properties));
84	props.type = BACKLIGHT_RAW;
85	props.max_brightness = EP93XX_MAX_BRIGHT;
86	bl = devm_backlight_device_register(&dev->dev, dev->name, &dev->dev,
87					ep93xxbl, &ep93xxbl_ops, &props);
88	if (IS_ERR(bl))
89		return PTR_ERR(bl);
90
91	bl->props.brightness = EP93XX_DEF_BRIGHT;
92
93	platform_set_drvdata(dev, bl);
94
95	ep93xxbl_update_status(bl);
96
97	return 0;
98}
99
100#ifdef CONFIG_PM_SLEEP
101static int ep93xxbl_suspend(struct device *dev)
102{
103	struct backlight_device *bl = dev_get_drvdata(dev);
104
105	return ep93xxbl_set(bl, 0);
106}
107
108static int ep93xxbl_resume(struct device *dev)
109{
110	struct backlight_device *bl = dev_get_drvdata(dev);
111
112	backlight_update_status(bl);
113	return 0;
114}
115#endif
116
117static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);
118
119static struct platform_driver ep93xxbl_driver = {
120	.driver		= {
121		.name	= "ep93xx-bl",
122		.pm	= &ep93xxbl_pm_ops,
123	},
124	.probe		= ep93xxbl_probe,
125};
126
127module_platform_driver(ep93xxbl_driver);
128
129MODULE_DESCRIPTION("EP93xx Backlight Driver");
130MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
131MODULE_LICENSE("GPL");
132MODULE_ALIAS("platform:ep93xx-bl");
133