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
21 struct ep93xxbl {
22 void __iomem *mmio;
23 int brightness;
24 };
25
ep93xxbl_set(struct backlight_device * bl,int brightness)26 static 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
ep93xxbl_update_status(struct backlight_device * bl)37 static int ep93xxbl_update_status(struct backlight_device *bl)
38 {
39 return ep93xxbl_set(bl, backlight_get_brightness(bl));
40 }
41
ep93xxbl_get_brightness(struct backlight_device * bl)42 static int ep93xxbl_get_brightness(struct backlight_device *bl)
43 {
44 struct ep93xxbl *ep93xxbl = bl_get_data(bl);
45
46 return ep93xxbl->brightness;
47 }
48
49 static const struct backlight_ops ep93xxbl_ops = {
50 .update_status = ep93xxbl_update_status,
51 .get_brightness = ep93xxbl_get_brightness,
52 };
53
ep93xxbl_probe(struct platform_device * dev)54 static 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
ep93xxbl_suspend(struct device * dev)101 static 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
ep93xxbl_resume(struct device * dev)108 static 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
117 static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);
118
119 static struct platform_driver ep93xxbl_driver = {
120 .driver = {
121 .name = "ep93xx-bl",
122 .pm = &ep93xxbl_pm_ops,
123 },
124 .probe = ep93xxbl_probe,
125 };
126
127 module_platform_driver(ep93xxbl_driver);
128
129 MODULE_DESCRIPTION("EP93xx Backlight Driver");
130 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
131 MODULE_LICENSE("GPL");
132 MODULE_ALIAS("platform:ep93xx-bl");
133