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[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: eric miao <[email protected]> Signed-off-by: Russell King <[email protected]>
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eric miao
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Russell King
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Jul 3, 2008
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Original file line number | Diff line number | Diff line change |
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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. | ||
*/ | ||
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#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> | ||
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struct pwm_bl_data { | ||
struct pwm_device *pwm; | ||
unsigned int period; | ||
}; | ||
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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; | ||
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if (bl->props.power != FB_BLANK_UNBLANK) | ||
brightness = 0; | ||
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if (bl->props.fb_blank != FB_BLANK_UNBLANK) | ||
brightness = 0; | ||
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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; | ||
} | ||
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static int pwm_backlight_get_brightness(struct backlight_device *bl) | ||
{ | ||
return bl->props.brightness; | ||
} | ||
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static struct backlight_ops pwm_backlight_ops = { | ||
.update_status = pwm_backlight_update_status, | ||
.get_brightness = pwm_backlight_get_brightness, | ||
}; | ||
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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; | ||
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if (!data) | ||
return -EINVAL; | ||
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pb = kzalloc(sizeof(*pb), GFP_KERNEL); | ||
if (!pb) | ||
return -ENOMEM; | ||
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pb->period = data->pwm_period_ns; | ||
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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; | ||
} | ||
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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); | ||
} | ||
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bl->props.max_brightness = data->max_brightness; | ||
bl->props.brightness = data->dft_brightness; | ||
backlight_update_status(bl); | ||
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platform_set_drvdata(pdev, bl); | ||
return 0; | ||
} | ||
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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); | ||
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backlight_device_unregister(bl); | ||
pwm_config(pb->pwm, 0, pb->period); | ||
pwm_disable(pb->pwm); | ||
pwm_free(pb->pwm); | ||
kfree(pb); | ||
return 0; | ||
} | ||
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#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); | ||
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pwm_config(pb->pwm, 0, pb->period); | ||
pwm_disable(pb->pwm); | ||
return 0; | ||
} | ||
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static int pwm_backlight_resume(struct platform_device *pdev) | ||
{ | ||
struct backlight_device *bl = platform_get_drvdata(pdev); | ||
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backlight_update_status(bl); | ||
return 0; | ||
} | ||
#else | ||
#define pwm_backlight_suspend NULL | ||
#define pwm_backlight_resume NULL | ||
#endif | ||
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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, | ||
}; | ||
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static int __init pwm_backlight_init(void) | ||
{ | ||
return platform_driver_register(&pwm_backlight_driver); | ||
} | ||
module_init(pwm_backlight_init); | ||
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static void __exit pwm_backlight_exit(void) | ||
{ | ||
platform_driver_unregister(&pwm_backlight_driver); | ||
} | ||
module_exit(pwm_backlight_exit); | ||
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MODULE_DESCRIPTION("PWM based Backlight Driver"); | ||
MODULE_LICENSE("GPL"); |
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,14 @@ | ||
/* | ||
* Generic PWM backlight driver data - see drivers/video/backlight/pwm_bl.c | ||
*/ | ||
#ifndef __LINUX_PWM_BACKLIGHT_H | ||
#define __LINUX_PWM_BACKLIGHT_H | ||
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struct platform_pwm_backlight_data { | ||
int pwm_id; | ||
unsigned int max_brightness; | ||
unsigned int dft_brightness; | ||
unsigned int pwm_period_ns; | ||
}; | ||
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#endif |