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/*
* Copyright (C) 2008 Atmel Corporation
*
* Backlight driver using Atmel PWM peripheral.
*
* 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/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/fb.h>
#include <linux/gpio.h>
#include <linux/backlight.h>
#include <linux/atmel_pwm.h>
#include <linux/atmel-pwm-bl.h>
#include <linux/slab.h>
struct atmel_pwm_bl {
const struct atmel_pwm_bl_platform_data *pdata;
struct backlight_device *bldev;
struct platform_device *pdev;
struct pwm_channel pwmc;
int gpio_on;
};
static void atmel_pwm_bl_set_gpio_on(struct atmel_pwm_bl *pwmbl, int on)
{
if (!gpio_is_valid(pwmbl->gpio_on))
return;
gpio_set_value(pwmbl->gpio_on, on ^ pwmbl->pdata->on_active_low);
}
static int atmel_pwm_bl_set_intensity(struct backlight_device *bd)
{
struct atmel_pwm_bl *pwmbl = bl_get_data(bd);
int intensity = bd->props.brightness;
int pwm_duty;
if (bd->props.power != FB_BLANK_UNBLANK)
intensity = 0;
if (bd->props.fb_blank != FB_BLANK_UNBLANK)
intensity = 0;
if (pwmbl->pdata->pwm_active_low)
pwm_duty = pwmbl->pdata->pwm_duty_min + intensity;
else
pwm_duty = pwmbl->pdata->pwm_duty_max - intensity;
if (pwm_duty > pwmbl->pdata->pwm_duty_max)
pwm_duty = pwmbl->pdata->pwm_duty_max;
if (pwm_duty < pwmbl->pdata->pwm_duty_min)
pwm_duty = pwmbl->pdata->pwm_duty_min;
if (!intensity) {
atmel_pwm_bl_set_gpio_on(pwmbl, 0);
pwm_channel_writel(&pwmbl->pwmc, PWM_CUPD, pwm_duty);
pwm_channel_disable(&pwmbl->pwmc);
} else {
pwm_channel_enable(&pwmbl->pwmc);
pwm_channel_writel(&pwmbl->pwmc, PWM_CUPD, pwm_duty);
atmel_pwm_bl_set_gpio_on(pwmbl, 1);
}
return 0;
}
static int atmel_pwm_bl_get_intensity(struct backlight_device *bd)
{
struct atmel_pwm_bl *pwmbl = bl_get_data(bd);
u32 cdty;
u32 intensity;
cdty = pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY);
if (pwmbl->pdata->pwm_active_low)
intensity = cdty - pwmbl->pdata->pwm_duty_min;
else
intensity = pwmbl->pdata->pwm_duty_max - cdty;
return intensity & 0xffff;
}
static int atmel_pwm_bl_init_pwm(struct atmel_pwm_bl *pwmbl)
{
unsigned long pwm_rate = pwmbl->pwmc.mck;
unsigned long prescale = DIV_ROUND_UP(pwm_rate,
(pwmbl->pdata->pwm_frequency *
pwmbl->pdata->pwm_compare_max)) - 1;
/*
* Prescale must be power of two and maximum 0xf in size because of
* hardware limit. PWM speed will be:
* PWM module clock speed / (2 ^ prescale).
*/
prescale = fls(prescale);
if (prescale > 0xf)
prescale = 0xf;
pwm_channel_writel(&pwmbl->pwmc, PWM_CMR, prescale);
pwm_channel_writel(&pwmbl->pwmc, PWM_CDTY,
pwmbl->pdata->pwm_duty_min +
pwmbl->bldev->props.brightness);
pwm_channel_writel(&pwmbl->pwmc, PWM_CPRD,
pwmbl->pdata->pwm_compare_max);
dev_info(&pwmbl->pdev->dev, "Atmel PWM backlight driver (%lu Hz)\n",
pwmbl->pwmc.mck / pwmbl->pdata->pwm_compare_max /
(1 << prescale));
return pwm_channel_enable(&pwmbl->pwmc);
}
static const struct backlight_ops atmel_pwm_bl_ops = {
.get_brightness = atmel_pwm_bl_get_intensity,
.update_status = atmel_pwm_bl_set_intensity,
};
static int atmel_pwm_bl_probe(struct platform_device *pdev)
{
struct backlight_properties props;
const struct atmel_pwm_bl_platform_data *pdata;
struct backlight_device *bldev;
struct atmel_pwm_bl *pwmbl;
unsigned long flags;
int retval;
pdata = dev_get_platdata(&pdev->dev);
if (!pdata)
return -ENODEV;
if (pdata->pwm_compare_max < pdata->pwm_duty_max ||
pdata->pwm_duty_min > pdata->pwm_duty_max ||
pdata->pwm_frequency == 0)
return -EINVAL;
pwmbl = devm_kzalloc(&pdev->dev, sizeof(struct atmel_pwm_bl),
GFP_KERNEL);
if (!pwmbl)
return -ENOMEM;
pwmbl->pdev = pdev;
pwmbl->pdata = pdata;
pwmbl->gpio_on = pdata->gpio_on;
retval = pwm_channel_alloc(pdata->pwm_channel, &pwmbl->pwmc);
if (retval)
return retval;
if (gpio_is_valid(pwmbl->gpio_on)) {
/* Turn display off by default. */
if (pdata->on_active_low)
flags = GPIOF_OUT_INIT_HIGH;
else
flags = GPIOF_OUT_INIT_LOW;
retval = devm_gpio_request_one(&pdev->dev, pwmbl->gpio_on,
flags, "gpio_atmel_pwm_bl");
if (retval)
goto err_free_pwm;
}
memset(&props, 0, sizeof(struct backlight_properties));
props.type = BACKLIGHT_RAW;
props.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min;
bldev = devm_backlight_device_register(&pdev->dev, "atmel-pwm-bl",
&pdev->dev, pwmbl, &atmel_pwm_bl_ops,
&props);
if (IS_ERR(bldev)) {
retval = PTR_ERR(bldev);
goto err_free_pwm;
}
pwmbl->bldev = bldev;
platform_set_drvdata(pdev, pwmbl);
/* Power up the backlight by default at middle intesity. */
bldev->props.power = FB_BLANK_UNBLANK;
bldev->props.brightness = bldev->props.max_brightness / 2;
retval = atmel_pwm_bl_init_pwm(pwmbl);
if (retval)
goto err_free_pwm;
atmel_pwm_bl_set_intensity(bldev);
return 0;
err_free_pwm:
pwm_channel_free(&pwmbl->pwmc);
return retval;
}
static int atmel_pwm_bl_remove(struct platform_device *pdev)
{
struct atmel_pwm_bl *pwmbl = platform_get_drvdata(pdev);
atmel_pwm_bl_set_gpio_on(pwmbl, 0);
pwm_channel_disable(&pwmbl->pwmc);
pwm_channel_free(&pwmbl->pwmc);
return 0;
}
static struct platform_driver atmel_pwm_bl_driver = {
.driver = {
.name = "atmel-pwm-bl",
},
/* REVISIT add suspend() and resume() */
.probe = atmel_pwm_bl_probe,
.remove = atmel_pwm_bl_remove,
};
module_platform_driver(atmel_pwm_bl_driver);
MODULE_AUTHOR("Hans-Christian egtvedt <hans-christian.egtvedt@atmel.com>");
MODULE_DESCRIPTION("Atmel PWM backlight driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:atmel-pwm-bl");
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