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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Driver for the Cirrus EP93xx lcd backlight4 *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 25518#define EP93XX_MAX_BRIGHT 25519#define EP93XX_DEF_BRIGHT 12820 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 are71 * sharing the register space with the framebuffer driver (see72 * drivers/video/ep93xx-fb.c) and doing so will cause the second73 * loaded driver to return -EBUSY.74 *75 * NOTE: No locking is required; the framebuffer does not touch76 * 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_SLEEP101static 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#endif116 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");133