cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ep93xx_bl.c (3213B)

      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	return ep93xxbl_set(bl, backlight_get_brightness(bl));
     40}
     41
     42static int ep93xxbl_get_brightness(struct backlight_device *bl)
     43{
     44	struct ep93xxbl *ep93xxbl = bl_get_data(bl);
     45
     46	return ep93xxbl->brightness;
     47}
     48
     49static const struct backlight_ops ep93xxbl_ops = {
     50	.update_status	= ep93xxbl_update_status,
     51	.get_brightness	= ep93xxbl_get_brightness,
     52};
     53
     54static 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
    101static 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
    108static 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
    117static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);
    118
    119static struct platform_driver ep93xxbl_driver = {
    120	.driver		= {
    121		.name	= "ep93xx-bl",
    122		.pm	= &ep93xxbl_pm_ops,
    123	},
    124	.probe		= ep93xxbl_probe,
    125};
    126
    127module_platform_driver(ep93xxbl_driver);
    128
    129MODULE_DESCRIPTION("EP93xx Backlight Driver");
    130MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
    131MODULE_LICENSE("GPL");
    132MODULE_ALIAS("platform:ep93xx-bl");