mini2440 backlight驱动--linux-3.10.59

/* linux/drivers/video/mini2440_backlight.c

* Copyright (c) 2013 Feng Guoqing

*

* mini2440 LCD backlight Driver

*

* This file is subject to the terms and conditions of the GNU General Public

* License. See the file COPYING in the main directory of this archive for

* more details.

*

*/

#include <linux/errno.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/slab.h>

#include <linux/input.h>

#include <linux/init.h>

#include <linux/serio.h>

#include <linux/delay.h>

#include <linux/clk.h>

#include <linux/miscdevice.h>

#include <linux/gpio.h>

#include <asm/io.h>

#include <asm/irq.h>

#include <asm/uaccess.h>

#include <mach/regs-clock.h>

#include <plat/regs-timer.h>

#include <mach/regs-gpio.h>

#include <linux/cdev.h>

#define DEVICE_NAME "backlight"

static unsigned int bl_state;

static inline void set_bl(int state) {

bl_state = !!state;

gpio_set_value(S3C2410_GPG(4), bl_state);

}

static inline unsigned int get_bl(void) {

return bl_state;

}

static ssize_t dev_write(struct file *file, const char *buffer,

size_t count, loff_t * ppos) {

unsigned char ch;

int ret;

if (count == 0) {

return count;

}

ret = copy_from_user(&ch, buffer, sizeof ch) ? -EFAULT : 0;

if (ret) {

return ret;

}

ch &= 0x01;

set_bl(ch);

return count;

}

static ssize_t dev_read(struct file *filp, char *buffer,

size_t count, loff_t *ppos) {

int ret;

unsigned char str[] = {'0', '1' };

if (count == 0) {

return 0;

}

ret = copy_to_user(buffer, str + get_bl(),sizeof(unsigned char) ) ? -EFAULT : 0;

if (ret) {

return ret;

}

return sizeof(unsigned char);

}

static struct file_operations dev_fops = {

owner: THIS_MODULE,

read:dev_read,

write: dev_write,

};

static struct miscdevice misc = {

.minor = MISC_DYNAMIC_MINOR,

.name = DEVICE_NAME,

.fops = &dev_fops,

};

static int __init dev_init(void)

{

int ret;

ret = misc_register(&misc);

printk(DEVICE_NAME"\tinitialized\n");

s3c_gpio_cfgpin(S3C2410_GPG(4), S3C2410_GPIO_OUTPUT);

set_bl(1);

return ret;

}

static void __exit dev_exit(void)

{

misc_deregister(&misc);

}

module_init(dev_init);

module_exit(dev_exit);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("FriendlyARM Inc.");