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