drivers/video/backlight/ep93xx_bl.c

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