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