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Commit 42796d37 authored by eric miao's avatar eric miao Committed by Russell King
Browse files

[ARM] pxa: add generic PWM backlight driver 



Patch mostly from Eric Miao, with minor edits by rmk to convert
Eric's driver to a generic PWM-based backlight driver.

Signed-off-by: default avatareric miao <eric.miao@marvell.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent c860d701

drivers/video/backlight/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -112,3 +112,10 @@ config BACKLIGHT_CARILLO_RANCH 
	help

	  If you have a Intel LE80578 (Carillo Ranch) say Y to enable the

	  backlight driver.



config BACKLIGHT_PWM

	tristate "Generic PWM based Backlight Driver"

	depends on BACKLIGHT_CLASS_DEVICE && HAVE_PWM

	help

	  If you have a LCD backlight adjustable by PWM, say Y to enable

	  this driver.

drivers/video/backlight/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -10,3 +10,4 @@ obj-$(CONFIG_BACKLIGHT_LOCOMO) += locomolcd.o 
obj-$(CONFIG_BACKLIGHT_OMAP1)	+= omap1_bl.o

obj-$(CONFIG_BACKLIGHT_PROGEAR) += progear_bl.o

obj-$(CONFIG_BACKLIGHT_CARILLO_RANCH) += cr_bllcd.o

obj-$(CONFIG_BACKLIGHT_PWM)	+= pwm_bl.o

drivers/video/backlight/pwm_bl.c

0 → 100644
+160 −0
Original line number Diff line number Diff line 
/*

 * linux/drivers/video/backlight/pwm_bl.c

 *

 * simple PWM based backlight control, board code has to setup

 * 1) pin configuration so PWM waveforms can output

 * 2) platform_data casts to the PWM id (0/1/2/3 on PXA)

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 */



#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/platform_device.h>

#include <linux/fb.h>

#include <linux/backlight.h>

#include <linux/err.h>

#include <linux/pwm.h>

#include <linux/pwm_backlight.h>



struct pwm_bl_data {

	struct pwm_device	*pwm;

	unsigned int		period;

};



static int pwm_backlight_update_status(struct backlight_device *bl)

{

	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);

	int brightness = bl->props.brightness;

	int max = bl->props.max_brightness;



	if (bl->props.power != FB_BLANK_UNBLANK)

		brightness = 0;



	if (bl->props.fb_blank != FB_BLANK_UNBLANK)

		brightness = 0;



	if (brightness == 0) {

		pwm_config(pb->pwm, 0, pb->period);

		pwm_disable(pb->pwm);

	} else {

		pwm_config(pb->pwm, brightness * pb->period / max, pb->period);

		pwm_enable(pb->pwm);

	}

	return 0;

}



static int pwm_backlight_get_brightness(struct backlight_device *bl)

{

	return bl->props.brightness;

}



static struct backlight_ops pwm_backlight_ops = {

	.update_status	= pwm_backlight_update_status,

	.get_brightness	= pwm_backlight_get_brightness,

};



static int pwm_backlight_probe(struct platform_device *pdev)

{

	struct platform_pwm_backlight_data *data = pdev->dev.platform_data;

	struct backlight_device *bl;

	struct pwm_bl_data *pb;



	if (!data)

		return -EINVAL;



	pb = kzalloc(sizeof(*pb), GFP_KERNEL);

	if (!pb)

		return -ENOMEM;



	pb->period = data->pwm_period_ns;



	pb->pwm = pwm_request(data->pwm_id, "backlight");

	if (pb->pwm == NULL) {

		dev_err(&pdev->dev, "unable to request PWM for backlight\n");

		kfree(pb);

		return -EBUSY;

	}



	bl = backlight_device_register(pdev->name, &pdev->dev,

			pb, &pwm_backlight_ops);

	if (IS_ERR(bl)) {

		dev_err(&pdev->dev, "failed to register backlight\n");

		pwm_free(pb->pwm);

		kfree(pb);

		return PTR_ERR(bl);

	}



	bl->props.max_brightness = data->max_brightness;

	bl->props.brightness = data->dft_brightness;

	backlight_update_status(bl);



	platform_set_drvdata(pdev, bl);

	return 0;

}



static int pwm_backlight_remove(struct platform_device *pdev)

{

	struct backlight_device *bl = platform_get_drvdata(pdev);

	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);



	backlight_device_unregister(bl);

	pwm_config(pb->pwm, 0, pb->period);

	pwm_disable(pb->pwm);

	pwm_free(pb->pwm);

	kfree(pb);

	return 0;

}



#ifdef CONFIG_PM

static int pwm_backlight_suspend(struct platform_device *pdev,

				 pm_message_t state)

{

	struct backlight_device *bl = platform_get_drvdata(pdev);

	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);



	pwm_config(pb->pwm, 0, pb->period);

	pwm_disable(pb->pwm);

	return 0;

}



static int pwm_backlight_resume(struct platform_device *pdev)

{

	struct backlight_device *bl = platform_get_drvdata(pdev);



	backlight_update_status(bl);

	return 0;

}

#else

#define pwm_backlight_suspend	NULL

#define pwm_backlight_resume	NULL

#endif



static struct platform_driver pwm_backlight_driver = {

	.driver		= {

		.name	= "pwm-backlight",

		.owner	= THIS_MODULE,

	},

	.probe		= pwm_backlight_probe,

	.remove		= pwm_backlight_remove,

	.suspend	= pwm_backlight_suspend,

	.resume		= pwm_backlight_resume,

};



static int __init pwm_backlight_init(void)

{

	return platform_driver_register(&pwm_backlight_driver);

}

module_init(pwm_backlight_init);



static void __exit pwm_backlight_exit(void)

{

	platform_driver_unregister(&pwm_backlight_driver);

}

module_exit(pwm_backlight_exit);



MODULE_DESCRIPTION("PWM based Backlight Driver");

MODULE_LICENSE("GPL");

include/linux/pwm_backlight.h

0 → 100644
+14 −0
Original line number Diff line number Diff line 
/*

 * Generic PWM backlight driver data - see drivers/video/backlight/pwm_bl.c

 */

#ifndef __LINUX_PWM_BACKLIGHT_H

#define __LINUX_PWM_BACKLIGHT_H



struct platform_pwm_backlight_data {

	int pwm_id;

	unsigned int max_brightness;

	unsigned int dft_brightness;

	unsigned int pwm_period_ns;

};



#endif