1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Driver for the Cirrus EP93xx lcd backlight
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (c) 2010 H Hartley Sweeten <hsweeten@visionengravers.com>
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * This driver controls the pulse width modulated brightness control output,
8*4882a593Smuzhiyun * BRIGHT, on the Cirrus EP9307, EP9312, and EP9315 processors.
9*4882a593Smuzhiyun */
10*4882a593Smuzhiyun
11*4882a593Smuzhiyun #include <linux/module.h>
12*4882a593Smuzhiyun #include <linux/platform_device.h>
13*4882a593Smuzhiyun #include <linux/io.h>
14*4882a593Smuzhiyun #include <linux/fb.h>
15*4882a593Smuzhiyun #include <linux/backlight.h>
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun #define EP93XX_MAX_COUNT 255
18*4882a593Smuzhiyun #define EP93XX_MAX_BRIGHT 255
19*4882a593Smuzhiyun #define EP93XX_DEF_BRIGHT 128
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun struct ep93xxbl {
22*4882a593Smuzhiyun void __iomem *mmio;
23*4882a593Smuzhiyun int brightness;
24*4882a593Smuzhiyun };
25*4882a593Smuzhiyun
ep93xxbl_set(struct backlight_device * bl,int brightness)26*4882a593Smuzhiyun static int ep93xxbl_set(struct backlight_device *bl, int brightness)
27*4882a593Smuzhiyun {
28*4882a593Smuzhiyun struct ep93xxbl *ep93xxbl = bl_get_data(bl);
29*4882a593Smuzhiyun
30*4882a593Smuzhiyun writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio);
31*4882a593Smuzhiyun
32*4882a593Smuzhiyun ep93xxbl->brightness = brightness;
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun return 0;
35*4882a593Smuzhiyun }
36*4882a593Smuzhiyun
ep93xxbl_update_status(struct backlight_device * bl)37*4882a593Smuzhiyun static int ep93xxbl_update_status(struct backlight_device *bl)
38*4882a593Smuzhiyun {
39*4882a593Smuzhiyun return ep93xxbl_set(bl, backlight_get_brightness(bl));
40*4882a593Smuzhiyun }
41*4882a593Smuzhiyun
ep93xxbl_get_brightness(struct backlight_device * bl)42*4882a593Smuzhiyun static int ep93xxbl_get_brightness(struct backlight_device *bl)
43*4882a593Smuzhiyun {
44*4882a593Smuzhiyun struct ep93xxbl *ep93xxbl = bl_get_data(bl);
45*4882a593Smuzhiyun
46*4882a593Smuzhiyun return ep93xxbl->brightness;
47*4882a593Smuzhiyun }
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun static const struct backlight_ops ep93xxbl_ops = {
50*4882a593Smuzhiyun .update_status = ep93xxbl_update_status,
51*4882a593Smuzhiyun .get_brightness = ep93xxbl_get_brightness,
52*4882a593Smuzhiyun };
53*4882a593Smuzhiyun
ep93xxbl_probe(struct platform_device * dev)54*4882a593Smuzhiyun static int ep93xxbl_probe(struct platform_device *dev)
55*4882a593Smuzhiyun {
56*4882a593Smuzhiyun struct ep93xxbl *ep93xxbl;
57*4882a593Smuzhiyun struct backlight_device *bl;
58*4882a593Smuzhiyun struct backlight_properties props;
59*4882a593Smuzhiyun struct resource *res;
60*4882a593Smuzhiyun
61*4882a593Smuzhiyun ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL);
62*4882a593Smuzhiyun if (!ep93xxbl)
63*4882a593Smuzhiyun return -ENOMEM;
64*4882a593Smuzhiyun
65*4882a593Smuzhiyun res = platform_get_resource(dev, IORESOURCE_MEM, 0);
66*4882a593Smuzhiyun if (!res)
67*4882a593Smuzhiyun return -ENXIO;
68*4882a593Smuzhiyun
69*4882a593Smuzhiyun /*
70*4882a593Smuzhiyun * FIXME - We don't do a request_mem_region here because we are
71*4882a593Smuzhiyun * sharing the register space with the framebuffer driver (see
72*4882a593Smuzhiyun * drivers/video/ep93xx-fb.c) and doing so will cause the second
73*4882a593Smuzhiyun * loaded driver to return -EBUSY.
74*4882a593Smuzhiyun *
75*4882a593Smuzhiyun * NOTE: No locking is required; the framebuffer does not touch
76*4882a593Smuzhiyun * this register.
77*4882a593Smuzhiyun */
78*4882a593Smuzhiyun ep93xxbl->mmio = devm_ioremap(&dev->dev, res->start,
79*4882a593Smuzhiyun resource_size(res));
80*4882a593Smuzhiyun if (!ep93xxbl->mmio)
81*4882a593Smuzhiyun return -ENXIO;
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun memset(&props, 0, sizeof(struct backlight_properties));
84*4882a593Smuzhiyun props.type = BACKLIGHT_RAW;
85*4882a593Smuzhiyun props.max_brightness = EP93XX_MAX_BRIGHT;
86*4882a593Smuzhiyun bl = devm_backlight_device_register(&dev->dev, dev->name, &dev->dev,
87*4882a593Smuzhiyun ep93xxbl, &ep93xxbl_ops, &props);
88*4882a593Smuzhiyun if (IS_ERR(bl))
89*4882a593Smuzhiyun return PTR_ERR(bl);
90*4882a593Smuzhiyun
91*4882a593Smuzhiyun bl->props.brightness = EP93XX_DEF_BRIGHT;
92*4882a593Smuzhiyun
93*4882a593Smuzhiyun platform_set_drvdata(dev, bl);
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun ep93xxbl_update_status(bl);
96*4882a593Smuzhiyun
97*4882a593Smuzhiyun return 0;
98*4882a593Smuzhiyun }
99*4882a593Smuzhiyun
100*4882a593Smuzhiyun #ifdef CONFIG_PM_SLEEP
ep93xxbl_suspend(struct device * dev)101*4882a593Smuzhiyun static int ep93xxbl_suspend(struct device *dev)
102*4882a593Smuzhiyun {
103*4882a593Smuzhiyun struct backlight_device *bl = dev_get_drvdata(dev);
104*4882a593Smuzhiyun
105*4882a593Smuzhiyun return ep93xxbl_set(bl, 0);
106*4882a593Smuzhiyun }
107*4882a593Smuzhiyun
ep93xxbl_resume(struct device * dev)108*4882a593Smuzhiyun static int ep93xxbl_resume(struct device *dev)
109*4882a593Smuzhiyun {
110*4882a593Smuzhiyun struct backlight_device *bl = dev_get_drvdata(dev);
111*4882a593Smuzhiyun
112*4882a593Smuzhiyun backlight_update_status(bl);
113*4882a593Smuzhiyun return 0;
114*4882a593Smuzhiyun }
115*4882a593Smuzhiyun #endif
116*4882a593Smuzhiyun
117*4882a593Smuzhiyun static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);
118*4882a593Smuzhiyun
119*4882a593Smuzhiyun static struct platform_driver ep93xxbl_driver = {
120*4882a593Smuzhiyun .driver = {
121*4882a593Smuzhiyun .name = "ep93xx-bl",
122*4882a593Smuzhiyun .pm = &ep93xxbl_pm_ops,
123*4882a593Smuzhiyun },
124*4882a593Smuzhiyun .probe = ep93xxbl_probe,
125*4882a593Smuzhiyun };
126*4882a593Smuzhiyun
127*4882a593Smuzhiyun module_platform_driver(ep93xxbl_driver);
128*4882a593Smuzhiyun
129*4882a593Smuzhiyun MODULE_DESCRIPTION("EP93xx Backlight Driver");
130*4882a593Smuzhiyun MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
131*4882a593Smuzhiyun MODULE_LICENSE("GPL");
132*4882a593Smuzhiyun MODULE_ALIAS("platform:ep93xx-bl");
133