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// SPDX-License-Identifier: GPL-2.0-only
/*
* Driver for the Cirrus EP93xx lcd backlight
*
* Copyright (c) 2010 H Hartley Sweeten <hsweeten@visionengravers.com>
*
* This driver controls the pulse width modulated brightness control output,
* BRIGHT, on the Cirrus EP9307, EP9312, and EP9315 processors.
*/
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/fb.h>
#include <linux/backlight.h>
#define EP93XX_MAX_COUNT 255
#define EP93XX_MAX_BRIGHT 255
#define EP93XX_DEF_BRIGHT 128
struct ep93xxbl {
void __iomem *mmio;
int brightness;
};
static int ep93xxbl_set(struct backlight_device *bl, int brightness)
{
struct ep93xxbl *ep93xxbl = bl_get_data(bl);
writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio);
ep93xxbl->brightness = brightness;
return 0;
}
static int ep93xxbl_update_status(struct backlight_device *bl)
{
return ep93xxbl_set(bl, backlight_get_brightness(bl));
}
static int ep93xxbl_get_brightness(struct backlight_device *bl)
{
struct ep93xxbl *ep93xxbl = bl_get_data(bl);
return ep93xxbl->brightness;
}
static const struct backlight_ops ep93xxbl_ops = {
.update_status = ep93xxbl_update_status,
.get_brightness = ep93xxbl_get_brightness,
};
static int ep93xxbl_probe(struct platform_device *dev)
{
struct ep93xxbl *ep93xxbl;
struct backlight_device *bl;
struct backlight_properties props;
struct resource *res;
ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL);
if (!ep93xxbl)
return -ENOMEM;
res = platform_get_resource(dev, IORESOURCE_MEM, 0);
if (!res)
return -ENXIO;
/*
* FIXME - We don't do a request_mem_region here because we are
* sharing the register space with the framebuffer driver (see
* drivers/video/ep93xx-fb.c) and doing so will cause the second
* loaded driver to return -EBUSY.
*
* NOTE: No locking is required; the framebuffer does not touch
* this register.
*/
ep93xxbl->mmio = devm_ioremap(&dev->dev, res->start,
resource_size(res));
if (!ep93xxbl->mmio)
return -ENXIO;
memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_RAW;
props.max_brightness = EP93XX_MAX_BRIGHT;
bl = devm_backlight_device_register(&dev->dev, dev->name, &dev->dev,
ep93xxbl, &ep93xxbl_ops, &props);
if (IS_ERR(bl))
return PTR_ERR(bl);
bl->props.brightness = EP93XX_DEF_BRIGHT;
platform_set_drvdata(dev, bl);
ep93xxbl_update_status(bl);
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int ep93xxbl_suspend(struct device *dev)
{
struct backlight_device *bl = dev_get_drvdata(dev);
return ep93xxbl_set(bl, 0);
}
static int ep93xxbl_resume(struct device *dev)
{
struct backlight_device *bl = dev_get_drvdata(dev);
backlight_update_status(bl);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);
static struct platform_driver ep93xxbl_driver = {
.driver = {
.name = "ep93xx-bl",
.pm = &ep93xxbl_pm_ops,
},
.probe = ep93xxbl_probe,
};
module_platform_driver(ep93xxbl_driver);
MODULE_DESCRIPTION("EP93xx Backlight Driver");
MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ep93xx-bl");
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