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 | |
26 | static int ep93xxbl_set(struct backlight_device *bl, int brightness) |
27 | { |
28 | struct ep93xxbl *ep93xxbl = bl_get_data(bl_dev: bl); |
29 | |
30 | writel(val: (brightness << 8) | EP93XX_MAX_COUNT, addr: ep93xxbl->mmio); |
31 | |
32 | ep93xxbl->brightness = brightness; |
33 | |
34 | return 0; |
35 | } |
36 | |
37 | static int ep93xxbl_update_status(struct backlight_device *bl) |
38 | { |
39 | return ep93xxbl_set(bl, brightness: backlight_get_brightness(bd: bl)); |
40 | } |
41 | |
42 | static int ep93xxbl_get_brightness(struct backlight_device *bl) |
43 | { |
44 | struct ep93xxbl *ep93xxbl = bl_get_data(bl_dev: 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 | |
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->dev, size: 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->dev, offset: res->start, |
79 | size: 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->name, parent: &dev->dev, |
87 | devdata: ep93xxbl, ops: &ep93xxbl_ops, props: &props); |
88 | if (IS_ERR(ptr: bl)) |
89 | return PTR_ERR(ptr: bl); |
90 | |
91 | bl->props.brightness = EP93XX_DEF_BRIGHT; |
92 | |
93 | platform_set_drvdata(pdev: dev, data: bl); |
94 | |
95 | ep93xxbl_update_status(bl); |
96 | |
97 | return 0; |
98 | } |
99 | |
100 | #ifdef CONFIG_PM_SLEEP |
101 | static int ep93xxbl_suspend(struct device *dev) |
102 | { |
103 | struct backlight_device *bl = dev_get_drvdata(dev); |
104 | |
105 | return ep93xxbl_set(bl, brightness: 0); |
106 | } |
107 | |
108 | static int ep93xxbl_resume(struct device *dev) |
109 | { |
110 | struct backlight_device *bl = dev_get_drvdata(dev); |
111 | |
112 | backlight_update_status(bd: 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 | |