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/*
* 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");
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