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/* linux/arch/arm/plat-samsung/dev-backlight.c
* Copyright (c) 2011 Samsung Electronics Co., Ltd.
* Common infrastructure for PWM Backlight for Samsung boards
* 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/gpio.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/pwm_backlight.h>
#include <linux/slab.h>
#include <plat/devs.h>
#include <plat/gpio-cfg.h>
#include <plat/backlight.h>
static int samsung_bl_init(struct device *dev)
int ret = 0;
struct platform_device *timer_dev =
container_of(dev->parent, struct platform_device, dev);
struct samsung_bl_gpio_info *bl_gpio_info =
ret = gpio_request(bl_gpio_info->no, "Backlight");
if (ret) {
printk(KERN_ERR "failed to request GPIO for LCD Backlight\n");
return ret;
/* Configure GPIO pin with specific GPIO function for PWM timer */
s3c_gpio_cfgpin(bl_gpio_info->no, bl_gpio_info->func);
return 0;
static void samsung_bl_exit(struct device *dev)
struct platform_device *timer_dev =
container_of(dev->parent, struct platform_device, dev);
struct samsung_bl_gpio_info *bl_gpio_info =
s3c_gpio_cfgpin(bl_gpio_info->no, S3C_GPIO_OUTPUT);
/* Initialize few important fields of platform_pwm_backlight_data
* structure with default values. These fields can be overridden by
* board-specific values sent from machine file.
* For ease of operation, these fields are initialized with values
* used by most samsung boards.
* Users has the option of sending info about other parameters
* for their specific boards
static struct platform_pwm_backlight_data samsung_dfl_bl_data __initdata = {
.max_brightness = 255,
.dft_brightness = 255,
.pwm_period_ns = 78770,
.init = samsung_bl_init,
.exit = samsung_bl_exit,
static struct platform_device samsung_dfl_bl_device __initdata = {
.name = "pwm-backlight",
/* samsung_bl_set - Set board specific data (if any) provided by user for
* PWM Backlight control and register specific PWM and backlight device.
* @gpio_info: structure containing GPIO info for PWM timer
* @bl_data: structure containing Backlight control data
void samsung_bl_set(struct samsung_bl_gpio_info *gpio_info,
struct platform_pwm_backlight_data *bl_data)
int ret = 0;
struct platform_device *samsung_bl_device;
struct platform_pwm_backlight_data *samsung_bl_data;
samsung_bl_device = kmemdup(&samsung_dfl_bl_device,
sizeof(struct platform_device), GFP_KERNEL);
if (!samsung_bl_device) {
printk(KERN_ERR "%s: no memory for platform dev\n", __func__);
samsung_bl_data = s3c_set_platdata(&samsung_dfl_bl_data,
sizeof(struct platform_pwm_backlight_data), samsung_bl_device);
if (!samsung_bl_data) {
printk(KERN_ERR "%s: no memory for platform dev\n", __func__);
goto err_data;
/* Copy board specific data provided by user */
samsung_bl_data->pwm_id = bl_data->pwm_id;
samsung_bl_device->dev.parent =
if (bl_data->max_brightness)
samsung_bl_data->max_brightness = bl_data->max_brightness;
if (bl_data->dft_brightness)
samsung_bl_data->dft_brightness = bl_data->dft_brightness;
if (bl_data->lth_brightness)
samsung_bl_data->lth_brightness = bl_data->lth_brightness;
if (bl_data->pwm_period_ns)
samsung_bl_data->pwm_period_ns = bl_data->pwm_period_ns;
if (bl_data->init)
samsung_bl_data->init = bl_data->init;
if (bl_data->notify)
samsung_bl_data->notify = bl_data->notify;
if (bl_data->exit)
samsung_bl_data->exit = bl_data->exit;
if (bl_data->check_fb)
samsung_bl_data->check_fb = bl_data->check_fb;
/* Keep the GPIO info for future use */
s3c_device_timer[samsung_bl_data->pwm_id].dev.platform_data = gpio_info;
/* Register the specific PWM timer dev for Backlight control */
ret = platform_device_register(
if (ret) {
printk(KERN_ERR "failed to register pwm timer for backlight: %d\n", ret);
goto err_plat_reg1;
/* Register the Backlight dev */
ret = platform_device_register(samsung_bl_device);
if (ret) {
printk(KERN_ERR "failed to register backlight device: %d\n", ret);
goto err_plat_reg2;