/*
* 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/clk.h>
#include <linux/gpio.h>
#include <linux/backlight.h>
#include <linux/atmel_pwm.h>
#include <linux/atmel-pwm-bl.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 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) {
if (pwmbl->gpio_on != -1) {
gpio_set_value(pwmbl->gpio_on,
0 ^ pwmbl->pdata->on_active_low);
}
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);
if (pwmbl->gpio_on != -1) {
gpio_set_value(pwmbl->gpio_on,
1 ^ pwmbl->pdata->on_active_low);
}
}
return 0;
}
static int atmel_pwm_bl_get_intensity(struct backlight_device *bd)
{
struct atmel_pwm_bl *pwmbl = bl_get_data(bd);
u8 intensity;
if (pwmbl->pdata->pwm_active_low) {
intensity = pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY) -
pwmbl->pdata->pwm_duty_min;
} else {
intensity = pwmbl->pdata->pwm_duty_max -
pwm_channel_readl(&pwmbl->pwmc, PWM_CDTY);
}
return intensity;
}
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 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)
{
const struct atmel_pwm_bl_platform_data *pdata;
struct backlight_device *bldev;
struct atmel_pwm_bl *pwmbl;
int retval;
pwmbl = kzalloc(sizeof(struct atmel_pwm_bl), GFP_KERNEL);
if (!pwmbl)
return -ENOMEM;
pwmbl->pdev = pdev;
pdata = pdev->dev.platform_data;
if (!pdata) {
retval = -ENODEV;
goto err_free_mem;
}
if (pdata->pwm_compare_max < pdata->pwm_duty_max ||
pdata->pwm_duty_min > pdata->pwm_duty_max ||
pdata->pwm_frequency == 0) {
retval = -EINVAL;
goto err_free_mem;
}
pwmbl->pdata = pdata;
pwmbl->gpio_on = pdata->gpio_on;
retval = pwm_channel_alloc(pdata->pwm_channel, &pwmbl->pwmc);
if (retval)
goto err_free_mem;
if (pwmbl->gpio_on != -1) {
retval = gpio_request(pwmbl->gpio_on, "gpio_atmel_pwm_bl");
if (retval) {
pwmbl->gpio_on = -1;
goto err_free_pwm;
}
/* Turn display off by defatult. */
retval = gpio_direction_output(pwmbl->gpio_on,
0 ^ pdata->on_active_low);
if (retval)
goto err_free_gpio;
}
bldev = backlight_device_register("atmel-pwm-bl",
&pdev->dev, pwmbl, &atmel_pwm_bl_ops);
if (IS_ERR(bldev)) {
retval = PTR_ERR(bldev);
goto err_free_gpio;
}
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.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min;
bldev->props.brightness = bldev->props.max_brightness / 2;
retval = atmel_pwm_bl_init_pwm(pwmbl);
if (retval)
goto err_free_bl_dev;
atmel_pwm_bl_set_intensity(bldev);
return 0;
err_free_bl_dev:
platform_set_drvdata(pdev, NULL);
backlight_device_unregister(bldev);
err_free_gpio:
if (pwmbl->gpio_on != -1)
gpio_free(pwmbl->gpio_on);
err_free_pwm:
pwm_channel_free(&pwmbl->pwmc);
err_free_mem:
kfree(pwmbl);
return retval;
}
static int __exit atmel_pwm_bl_remove(struct platform_device *pdev)
{
struct atmel_pwm_bl *pwmbl = platform_get_drvdata(pdev);
if (pwmbl->gpio_on != -1) {
gpio_set_value(pwmbl->gpio_on, 0);
gpio_free(pwmbl->gpio_on);
}
pwm_channel_disable(&pwmbl->pwmc);
pwm_channel_free(&pwmbl->pwmc);
backlight_device_unregister(pwmbl->bldev);
platform_set_drvdata(pdev, NULL);
kfree(pwmbl);
return 0;
}
static struct platform_driver atmel_pwm_bl_driver = {
.driver = {
.name = "atmel-pwm-bl",
},
/* REVISIT add suspend() and resume() */
.remove = __exit_p(atmel_pwm_bl_remove),
};
static int __init atmel_pwm_bl_init(void)
{
return platform_driver_probe(&atmel_pwm_bl_driver, atmel_pwm_bl_probe);
}
module_init(atmel_pwm_bl_init);
static void __exit atmel_pwm_bl_exit(void)
{
platform_driver_unregister(&atmel_pwm_bl_driver);
}
module_exit(atmel_pwm_bl_exit);
MODULE_AUTHOR("Hans-Christian egtvedt <hans-christian.egtvedt@atmel.com>");
MODULE_DESCRIPTION("Atmel PWM backlight driver");
MODULE_LICENSE("GPL");
