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/io.h>
  17 #include <linux/fb.h>
  18 #include <linux/backlight.h>
  19
  20 #define EP93XX_MAX_COUNT                255
  21 #define EP93XX_MAX_BRIGHT               255
  22 #define EP93XX_DEF_BRIGHT               128
  23
  24 struct ep93xxbl {
  25         void __iomem *mmio;
  26         int brightness;
  27 };
  28
  29 static int ep93xxbl_set(struct backlight_device *bl, int brightness)
  30 {
  31         struct ep93xxbl *ep93xxbl = bl_get_data(bl);
  32
  33         writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio);
  34
  35         ep93xxbl->brightness = brightness;
  36
  37         return 0;
  38 }
  39
  40 static int ep93xxbl_update_status(struct backlight_device *bl)
  41 {
  42         int brightness = bl->props.brightness;
  43
  44         if (bl->props.power != FB_BLANK_UNBLANK ||
  45             bl->props.fb_blank != FB_BLANK_UNBLANK)
  46                 brightness = 0;
  47
  48         return ep93xxbl_set(bl, brightness);
  49 }
  50
  51 static int ep93xxbl_get_brightness(struct backlight_device *bl)
  52 {
  53         struct ep93xxbl *ep93xxbl = bl_get_data(bl);
  54
  55         return ep93xxbl->brightness;
  56 }
  57
  58 static const struct backlight_ops ep93xxbl_ops = {
  59         .update_status  = ep93xxbl_update_status,
  60         .get_brightness = ep93xxbl_get_brightness,
  61 };
  62
  63 static int ep93xxbl_probe(struct platform_device *dev)
  64 {
  65         struct ep93xxbl *ep93xxbl;
  66         struct backlight_device *bl;
  67         struct backlight_properties props;
  68         struct resource *res;
  69
  70         ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL);
  71         if (!ep93xxbl)
  72                 return -ENOMEM;
  73
  74         res = platform_get_resource(dev, IORESOURCE_MEM, 0);
  75         if (!res)
  76                 return -ENXIO;
  77
  78         /*
  79          * FIXME - We don't do a request_mem_region here because we are
  80          * sharing the register space with the framebuffer driver (see
  81          * drivers/video/ep93xx-fb.c) and doing so will cause the second
  82          * loaded driver to return -EBUSY.
  83          *
  84          * NOTE: No locking is required; the framebuffer does not touch
  85          * this register.
  86          */
  87         ep93xxbl->mmio = devm_ioremap(&dev->dev, res->start,
  88                                       resource_size(res));
  89         if (!ep93xxbl->mmio)
  90                 return -ENXIO;
  91
  92         memset(&props, 0, sizeof(struct backlight_properties));
  93         props.type = BACKLIGHT_RAW;
  94         props.max_brightness = EP93XX_MAX_BRIGHT;
  95         bl = devm_backlight_device_register(&dev->dev, dev->name, &dev->dev,
  96                                         ep93xxbl, &ep93xxbl_ops, &props);
  97         if (IS_ERR(bl))
  98                 return PTR_ERR(bl);
  99
 100         bl->props.brightness = EP93XX_DEF_BRIGHT;
 101
 102         platform_set_drvdata(dev, bl);
 103
 104         ep93xxbl_update_status(bl);
 105
 106         return 0;
 107 }
 108
 109 #ifdef CONFIG_PM_SLEEP
 110 static int ep93xxbl_suspend(struct device *dev)
 111 {
 112         struct backlight_device *bl = dev_get_drvdata(dev);
 113
 114         return ep93xxbl_set(bl, 0);
 115 }
 116
 117 static int ep93xxbl_resume(struct device *dev)
 118 {
 119         struct backlight_device *bl = dev_get_drvdata(dev);
 120
 121         backlight_update_status(bl);
 122         return 0;
 123 }
 124 #endif
 125
 126 static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);
 127
 128 static struct platform_driver ep93xxbl_driver = {
 129         .driver         = {
 130                 .name   = "ep93xx-bl",
 131                 .pm     = &ep93xxbl_pm_ops,
 132         },
 133         .probe          = ep93xxbl_probe,
 134 };
 135
 136 module_platform_driver(ep93xxbl_driver);
 137
 138 MODULE_DESCRIPTION("EP93xx Backlight Driver");
 139 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
 140 MODULE_LICENSE("GPL");
 141 MODULE_ALIAS("platform:ep93xx-bl");