LXR linux/drivers/video/backlight/ep93xx

   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
  21struct ep93xxbl {
  22        void __iomem *mmio;
  23        int brightness;
  24};
  25
  26static 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
  37static 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
  48static int ep93xxbl_get_brightness(struct backlight_device *bl)
  49{
  50        struct ep93xxbl *ep93xxbl = bl_get_data(bl);
  51
  52        return ep93xxbl->brightness;
  53}
  54
  55static const struct backlight_ops ep93xxbl_ops = {
  56        .update_status  = ep93xxbl_update_status,
  57        .get_brightness = ep93xxbl_get_brightness,
  58};
  59
  60static 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
 107static 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
 114static 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
 123static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);
 124
 125static struct platform_driver ep93xxbl_driver = {
 126        .driver         = {
 127                .name   = "ep93xx-bl",
 128                .pm     = &ep93xxbl_pm_ops,
 129        },
 130        .probe          = ep93xxbl_probe,
 131};
 132
 133module_platform_driver(ep93xxbl_driver);
 134
 135MODULE_DESCRIPTION("EP93xx Backlight Driver");
 136MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
 137MODULE_LICENSE("GPL");
 138MODULE_ALIAS("platform:ep93xx-bl");
 139