142 lines
3.4 KiB
C
142 lines
3.4 KiB
C
/*
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* Driver for the Cirrus EP93xx lcd backlight
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*
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* Copyright (c) 2010 H Hartley Sweeten <hsweeten@visionengravers.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This driver controls the pulse width modulated brightness control output,
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* BRIGHT, on the Cirrus EP9307, EP9312, and EP9315 processors.
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*/
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/io.h>
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#include <linux/fb.h>
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#include <linux/backlight.h>
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#define EP93XX_MAX_COUNT 255
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#define EP93XX_MAX_BRIGHT 255
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#define EP93XX_DEF_BRIGHT 128
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struct ep93xxbl {
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void __iomem *mmio;
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int brightness;
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};
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static int ep93xxbl_set(struct backlight_device *bl, int brightness)
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{
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struct ep93xxbl *ep93xxbl = bl_get_data(bl);
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writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio);
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ep93xxbl->brightness = brightness;
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return 0;
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}
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static int ep93xxbl_update_status(struct backlight_device *bl)
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{
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int brightness = bl->props.brightness;
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if (bl->props.power != FB_BLANK_UNBLANK ||
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bl->props.fb_blank != FB_BLANK_UNBLANK)
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brightness = 0;
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return ep93xxbl_set(bl, brightness);
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}
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static int ep93xxbl_get_brightness(struct backlight_device *bl)
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{
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struct ep93xxbl *ep93xxbl = bl_get_data(bl);
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return ep93xxbl->brightness;
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}
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static const struct backlight_ops ep93xxbl_ops = {
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.update_status = ep93xxbl_update_status,
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.get_brightness = ep93xxbl_get_brightness,
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};
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static int ep93xxbl_probe(struct platform_device *dev)
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{
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struct ep93xxbl *ep93xxbl;
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struct backlight_device *bl;
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struct backlight_properties props;
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struct resource *res;
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ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL);
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if (!ep93xxbl)
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return -ENOMEM;
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res = platform_get_resource(dev, IORESOURCE_MEM, 0);
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if (!res)
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return -ENXIO;
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/*
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* FIXME - We don't do a request_mem_region here because we are
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* sharing the register space with the framebuffer driver (see
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* drivers/video/ep93xx-fb.c) and doing so will cause the second
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* loaded driver to return -EBUSY.
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*
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* NOTE: No locking is required; the framebuffer does not touch
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* this register.
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*/
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ep93xxbl->mmio = devm_ioremap(&dev->dev, res->start,
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resource_size(res));
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if (!ep93xxbl->mmio)
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return -ENXIO;
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memset(&props, 0, sizeof(struct backlight_properties));
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props.type = BACKLIGHT_RAW;
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props.max_brightness = EP93XX_MAX_BRIGHT;
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bl = devm_backlight_device_register(&dev->dev, dev->name, &dev->dev,
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ep93xxbl, &ep93xxbl_ops, &props);
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if (IS_ERR(bl))
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return PTR_ERR(bl);
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bl->props.brightness = EP93XX_DEF_BRIGHT;
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platform_set_drvdata(dev, bl);
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ep93xxbl_update_status(bl);
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return 0;
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}
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#ifdef CONFIG_PM_SLEEP
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static int ep93xxbl_suspend(struct device *dev)
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{
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struct backlight_device *bl = dev_get_drvdata(dev);
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return ep93xxbl_set(bl, 0);
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}
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static int ep93xxbl_resume(struct device *dev)
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{
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struct backlight_device *bl = dev_get_drvdata(dev);
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backlight_update_status(bl);
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return 0;
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}
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#endif
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static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume);
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static struct platform_driver ep93xxbl_driver = {
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.driver = {
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.name = "ep93xx-bl",
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.pm = &ep93xxbl_pm_ops,
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},
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.probe = ep93xxbl_probe,
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};
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module_platform_driver(ep93xxbl_driver);
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MODULE_DESCRIPTION("EP93xx Backlight Driver");
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MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("platform:ep93xx-bl");
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