drivers/video/backlight/ep93xx_bl.c

   1 /*
   2  * Driver for the Cirrus EP93xx lcd backlight
   3  *
   4  * Copyright (c) 2010 H Hartley Sweeten <hsweeten@visionengravers.com>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * This driver controls the pulse width modulated brightness control output,
  11  * BRIGHT, on the Cirrus EP9307, EP9312, and EP9315 processors.
  12  */
  13
  14
  15 #include <linux/platform_device.h>
  16 #include <linux/io.h>
  17 #include <linux/fb.h>
  18 #include <linux/backlight.h>
  19
  20 #include <mach/hardware.h>
  21
  22 #define EP93XX_RASTER_REG(x)            (EP93XX_RASTER_BASE + (x))
  23 #define EP93XX_RASTER_BRIGHTNESS        EP93XX_RASTER_REG(0x20)
  24
  25 #define EP93XX_MAX_COUNT                255
  26 #define EP93XX_MAX_BRIGHT               255
  27 #define EP93XX_DEF_BRIGHT               128
  28
  29 struct ep93xxbl {
  30         void __iomem *mmio;
  31         int brightness;
  32 };
  33
  34 static int ep93xxbl_set(struct backlight_device *bl, int brightness)
  35 {
  36         struct ep93xxbl *ep93xxbl = bl_get_data(bl);
  37
  38         __raw_writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio);
  39
  40         ep93xxbl->brightness = brightness;
  41
  42         return 0;
  43 }
  44
  45 static int ep93xxbl_update_status(struct backlight_device *bl)
  46 {
  47         int brightness = bl->props.brightness;
  48
  49         if (bl->props.power != FB_BLANK_UNBLANK ||
  50             bl->props.fb_blank != FB_BLANK_UNBLANK)
  51                 brightness = 0;
  52
  53         return ep93xxbl_set(bl, brightness);
  54 }
  55
  56 static int ep93xxbl_get_brightness(struct backlight_device *bl)
  57 {
  58         struct ep93xxbl *ep93xxbl = bl_get_data(bl);
  59
  60         return ep93xxbl->brightness;
  61 }
  62
  63 static const struct backlight_ops ep93xxbl_ops = {
  64         .update_status  = ep93xxbl_update_status,
  65         .get_brightness = ep93xxbl_get_brightness,
  66 };
  67
  68 static int __init ep93xxbl_probe(struct platform_device *dev)
  69 {
  70         struct ep93xxbl *ep93xxbl;
  71         struct backlight_device *bl;
  72         struct backlight_properties props;
  73
  74         ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL);
  75         if (!ep93xxbl)
  76                 return -ENOMEM;
  77
  78         /*
  79          * This register is located in the range already ioremap'ed by
  80          * the framebuffer driver.  A MFD driver seems a bit of overkill
  81          * to handle this so use the static I/O mapping; this address
  82          * is already virtual.
  83          *
  84          * NOTE: No locking is required; the framebuffer does not touch
  85          * this register.
  86          */
  87         ep93xxbl->mmio = EP93XX_RASTER_BRIGHTNESS;
  88
  89         memset(&props, 0, sizeof(struct backlight_properties));
  90         props.max_brightness = EP93XX_MAX_BRIGHT;
  91         bl = backlight_device_register(dev->name, &dev->dev, ep93xxbl,
  92                                        &ep93xxbl_ops, &props);
  93         if (IS_ERR(bl))
  94                 return PTR_ERR(bl);
  95
  96         bl->props.brightness = EP93XX_DEF_BRIGHT;
  97
  98         platform_set_drvdata(dev, bl);
  99
 100         ep93xxbl_update_status(bl);
 101
 102         return 0;
 103 }
 104
 105 static int ep93xxbl_remove(struct platform_device *dev)
 106 {
 107         struct backlight_device *bl = platform_get_drvdata(dev);
 108
 109         backlight_device_unregister(bl);
 110         platform_set_drvdata(dev, NULL);
 111         return 0;
 112 }
 113
 114 #ifdef CONFIG_PM
 115 static int ep93xxbl_suspend(struct platform_device *dev, pm_message_t state)
 116 {
 117         struct backlight_device *bl = platform_get_drvdata(dev);
 118
 119         return ep93xxbl_set(bl, 0);
 120 }
 121
 122 static int ep93xxbl_resume(struct platform_device *dev)
 123 {
 124         struct backlight_device *bl = platform_get_drvdata(dev);
 125
 126         backlight_update_status(bl);
 127         return 0;
 128 }
 129 #else
 130 #define ep93xxbl_suspend        NULL
 131 #define ep93xxbl_resume         NULL
 132 #endif
 133
 134 static struct platform_driver ep93xxbl_driver = {
 135         .driver         = {
 136                 .name   = "ep93xx-bl",
 137                 .owner  = THIS_MODULE,
 138         },
 139         .probe          = ep93xxbl_probe,
 140         .remove         = __devexit_p(ep93xxbl_remove),
 141         .suspend        = ep93xxbl_suspend,
 142         .resume         = ep93xxbl_resume,
 143 };
 144
 145 static int __init ep93xxbl_init(void)
 146 {
 147         return platform_driver_register(&ep93xxbl_driver);
 148 }
 149 module_init(ep93xxbl_init);
 150
 151 static void __exit ep93xxbl_exit(void)
 152 {
 153         platform_driver_unregister(&ep93xxbl_driver);
 154 }
 155 module_exit(ep93xxbl_exit);
 156
 157 MODULE_DESCRIPTION("EP93xx Backlight Driver");
 158 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
 159 MODULE_LICENSE("GPL");
 160 MODULE_ALIAS("platform:ep93xx-bl");