mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-24 05:04:00 +08:00
3e074058d7
This patch adds a platform driver using the ATMEL PWM driver to control a backlight which requires a PWM signal and optional GPIO signal for discrete on/off signal. It has been tested on Favr-32 board from EarthLCD. The driver is configurable by supplying a struct with the platform data. See the include/linux/atmel-pwm-bl.h for details. The board code for Favr-32 will be submitted to the AVR32 kernel list. Signed-off-by: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com> Cc: Krzysztof Helt <krzysztof.h1@poczta.fm> Cc: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Richard Purdie <rpurdie@rpsys.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
245 lines
6.0 KiB
C
245 lines
6.0 KiB
C
/*
|
|
* 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");
|