08b3924b24
The EP9307, EP9312, and EP9315 processors include a framebuffer peripheral. This peripheral has a dedicated pwm output called BRIGHT that can be used to control the backlight on an LCD. Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com> Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
160 lines
3.8 KiB
C
160 lines
3.8 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/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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#include <mach/hardware.h>
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#define EP93XX_RASTER_REG(x) (EP93XX_RASTER_BASE + (x))
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#define EP93XX_RASTER_BRIGHTNESS EP93XX_RASTER_REG(0x20)
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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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__raw_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 __init 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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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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/*
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* This register is located in the range already ioremap'ed by
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* the framebuffer driver. A MFD driver seems a bit of overkill
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* to handle this so use the static I/O mapping; this address
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* is already virtual.
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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 = EP93XX_RASTER_BRIGHTNESS;
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memset(&props, 0, sizeof(struct backlight_properties));
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props.max_brightness = EP93XX_MAX_BRIGHT;
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bl = backlight_device_register(dev->name, &dev->dev, ep93xxbl,
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&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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static int ep93xxbl_remove(struct platform_device *dev)
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{
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struct backlight_device *bl = platform_get_drvdata(dev);
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backlight_device_unregister(bl);
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platform_set_drvdata(dev, NULL);
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return 0;
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}
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#ifdef CONFIG_PM
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static int ep93xxbl_suspend(struct platform_device *dev, pm_message_t state)
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{
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struct backlight_device *bl = platform_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 platform_device *dev)
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{
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struct backlight_device *bl = platform_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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#else
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#define ep93xxbl_suspend NULL
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#define ep93xxbl_resume NULL
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#endif
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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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.owner = THIS_MODULE,
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},
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.probe = ep93xxbl_probe,
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.remove = __devexit_p(ep93xxbl_remove),
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.suspend = ep93xxbl_suspend,
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.resume = ep93xxbl_resume,
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};
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static int __init ep93xxbl_init(void)
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{
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return platform_driver_register(&ep93xxbl_driver);
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}
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module_init(ep93xxbl_init);
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static void __exit ep93xxbl_exit(void)
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{
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platform_driver_unregister(&ep93xxbl_driver);
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}
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module_exit(ep93xxbl_exit);
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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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