[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 <eric.miao@marvell.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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@ -112,3 +112,10 @@ config BACKLIGHT_CARILLO_RANCH
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help
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If you have a Intel LE80578 (Carillo Ranch) say Y to enable the
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backlight driver.
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config BACKLIGHT_PWM
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tristate "Generic PWM based Backlight Driver"
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depends on BACKLIGHT_CLASS_DEVICE && HAVE_PWM
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help
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If you have a LCD backlight adjustable by PWM, say Y to enable
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this driver.
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@ -10,3 +10,4 @@ obj-$(CONFIG_BACKLIGHT_LOCOMO) += locomolcd.o
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obj-$(CONFIG_BACKLIGHT_OMAP1) += omap1_bl.o
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obj-$(CONFIG_BACKLIGHT_PROGEAR) += progear_bl.o
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obj-$(CONFIG_BACKLIGHT_CARILLO_RANCH) += cr_bllcd.o
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obj-$(CONFIG_BACKLIGHT_PWM) += pwm_bl.o
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@ -0,0 +1,160 @@
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/*
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* linux/drivers/video/backlight/pwm_bl.c
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*
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* simple PWM based backlight control, board code has to setup
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* 1) pin configuration so PWM waveforms can output
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* 2) platform_data casts to the PWM id (0/1/2/3 on PXA)
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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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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/fb.h>
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#include <linux/backlight.h>
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#include <linux/err.h>
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#include <linux/pwm.h>
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#include <linux/pwm_backlight.h>
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struct pwm_bl_data {
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struct pwm_device *pwm;
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unsigned int period;
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};
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static int pwm_backlight_update_status(struct backlight_device *bl)
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{
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struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
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int brightness = bl->props.brightness;
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int max = bl->props.max_brightness;
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if (bl->props.power != FB_BLANK_UNBLANK)
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brightness = 0;
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if (bl->props.fb_blank != FB_BLANK_UNBLANK)
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brightness = 0;
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if (brightness == 0) {
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pwm_config(pb->pwm, 0, pb->period);
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pwm_disable(pb->pwm);
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} else {
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pwm_config(pb->pwm, brightness * pb->period / max, pb->period);
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pwm_enable(pb->pwm);
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}
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return 0;
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}
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static int pwm_backlight_get_brightness(struct backlight_device *bl)
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{
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return bl->props.brightness;
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}
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static struct backlight_ops pwm_backlight_ops = {
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.update_status = pwm_backlight_update_status,
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.get_brightness = pwm_backlight_get_brightness,
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};
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static int pwm_backlight_probe(struct platform_device *pdev)
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{
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struct platform_pwm_backlight_data *data = pdev->dev.platform_data;
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struct backlight_device *bl;
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struct pwm_bl_data *pb;
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if (!data)
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return -EINVAL;
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pb = kzalloc(sizeof(*pb), GFP_KERNEL);
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if (!pb)
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return -ENOMEM;
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pb->period = data->pwm_period_ns;
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pb->pwm = pwm_request(data->pwm_id, "backlight");
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if (pb->pwm == NULL) {
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dev_err(&pdev->dev, "unable to request PWM for backlight\n");
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kfree(pb);
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return -EBUSY;
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}
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bl = backlight_device_register(pdev->name, &pdev->dev,
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pb, &pwm_backlight_ops);
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if (IS_ERR(bl)) {
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dev_err(&pdev->dev, "failed to register backlight\n");
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pwm_free(pb->pwm);
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kfree(pb);
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return PTR_ERR(bl);
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}
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bl->props.max_brightness = data->max_brightness;
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bl->props.brightness = data->dft_brightness;
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backlight_update_status(bl);
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platform_set_drvdata(pdev, bl);
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return 0;
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}
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static int pwm_backlight_remove(struct platform_device *pdev)
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{
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struct backlight_device *bl = platform_get_drvdata(pdev);
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struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
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backlight_device_unregister(bl);
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pwm_config(pb->pwm, 0, pb->period);
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pwm_disable(pb->pwm);
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pwm_free(pb->pwm);
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kfree(pb);
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return 0;
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}
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#ifdef CONFIG_PM
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static int pwm_backlight_suspend(struct platform_device *pdev,
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pm_message_t state)
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{
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struct backlight_device *bl = platform_get_drvdata(pdev);
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struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
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pwm_config(pb->pwm, 0, pb->period);
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pwm_disable(pb->pwm);
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return 0;
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}
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static int pwm_backlight_resume(struct platform_device *pdev)
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{
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struct backlight_device *bl = platform_get_drvdata(pdev);
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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 pwm_backlight_suspend NULL
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#define pwm_backlight_resume NULL
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#endif
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static struct platform_driver pwm_backlight_driver = {
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.driver = {
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.name = "pwm-backlight",
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.owner = THIS_MODULE,
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},
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.probe = pwm_backlight_probe,
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.remove = pwm_backlight_remove,
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.suspend = pwm_backlight_suspend,
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.resume = pwm_backlight_resume,
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};
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static int __init pwm_backlight_init(void)
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{
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return platform_driver_register(&pwm_backlight_driver);
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}
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module_init(pwm_backlight_init);
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static void __exit pwm_backlight_exit(void)
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{
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platform_driver_unregister(&pwm_backlight_driver);
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}
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module_exit(pwm_backlight_exit);
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MODULE_DESCRIPTION("PWM based Backlight Driver");
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MODULE_LICENSE("GPL");
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@ -0,0 +1,14 @@
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/*
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* Generic PWM backlight driver data - see drivers/video/backlight/pwm_bl.c
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*/
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#ifndef __LINUX_PWM_BACKLIGHT_H
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#define __LINUX_PWM_BACKLIGHT_H
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struct platform_pwm_backlight_data {
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int pwm_id;
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unsigned int max_brightness;
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unsigned int dft_brightness;
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unsigned int pwm_period_ns;
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};
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#endif
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