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 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
ep93xxbl_get_brightness(struct backlight_device * bl)48 static int ep93xxbl_get_brightness(struct backlight_device *bl)
49 {
50 struct ep93xxbl *ep93xxbl = bl_get_data(bl);
51
52 return ep93xxbl->brightness;
53 }
54
55 static const struct backlight_ops ep93xxbl_ops = {
56 .update_status = ep93xxbl_update_status,
57 .get_brightness = ep93xxbl_get_brightness,
58 };
59
ep93xxbl_probe(struct platform_device * dev)60 static 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
ep93xxbl_suspend(struct device * dev)107 static 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
ep93xxbl_resume(struct device * dev)114 static 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
123 static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);
124
125 static struct platform_driver ep93xxbl_driver = {
126 .driver = {
127 .name = "ep93xx-bl",
128 .pm = &ep93xxbl_pm_ops,
129 },
130 .probe = ep93xxbl_probe,
131 };
132
133 module_platform_driver(ep93xxbl_driver);
134
135 MODULE_DESCRIPTION("EP93xx Backlight Driver");
136 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
137 MODULE_LICENSE("GPL");
138 MODULE_ALIAS("platform:ep93xx-bl");
139
