1.編寫背光驅動。文件名為my2440_backlight.c

（1）

#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?<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"?//設備名稱
#define?DEVICE_MINOR?5?//次設備號，這里我們將設備注冊為misc設備，這種設備的主設備號都為10

static?int?my2440_backlight_ioctl(struct?inode?*inode,?

??????????????????????????????????struct?file?*file,?

??????????????????????????????????unsigned?int?cmd,?

??????????????????????????????????unsigned?long?arg)
{
????switch(cmd)
????{
????????case?0:

????????????//當接收的命令為0時，就將GPG4引腳設為低電平，關閉背光
????????????s3c2410_gpio_setpin(S3C2410_GPG4,?0);?
????????????printk(DEVICE_NAME?"?turn?off!\n");
????????????return?0;
????????case?1:

????????????//當接收的命令為1時，就將GPG4引腳設為高電平，開啟背光
????????????s3c2410_gpio_setpin(S3C2410_GPG4,?1);?
????????????printk(DEVICE_NAME?"?turn?on!\n");
????????????return?0;
????????default:
????????????return?-EINVAL;
????}
}

static?struct?file_operations?dev_fops?=?
{
????.owner?=?THIS_MODULE,
????.ioctl?=?my2440_backlight_ioctl,?//這里只使用控制IO口的方式來控制背光
};

static?struct?miscdevice?misc?=
{
????.minor?=?DEVICE_MINOR,
????.name?=?DEVICE_NAME,
????.fops?=?&dev_fops,
};

static?int?__init?dev_init(void)
{
????int?ret;

????ret?=?misc_register(&misc);?//注冊成misc設備

????if(ret?<?0)
????{
????????printk("Register?misc?device?fiald!");
????????return?ret;
????}


????//將GPG4口配置成輸出口
????s3c2410_gpio_cfgpin(S3C2410_GPG4,?S3C2410_GPG4_OUTP);?

????return?ret;
}

static?void?__exit?dev_exit(void)
{
????misc_deregister(&misc);?//注銷該misc設備
}

module_init(dev_init);
module_exit(dev_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Huang?Gang");
MODULE_DESCRIPTION("Backlight?control?for?my2440");

?

（2）制作Makefile，內容為：obj-m := my2440_backlight.o
（3）make -C /root/2410kernels/linux-2.6.25.20_v1.0.4/ M=$(pwd) modules

2.背光應用程序：

?

#include?<stdio.h>
#include?<stdlib.h>
#include?<fcntl.h>
#include?<sys/ioctl.h>

int?main(int?argc,?char?**argv)
{
????int?turn;
????int?fd;
????
????//檢測命令后面帶的參數
????if(argc?==?1?||?argc?>?2)
????{
????????printf("Usage:?backlight?on|off!\n");
????????exit(1);
????}
????
????//打開背光設備
????fd?=?open("/dev/backlight",?O_RDWR);
????
????if(fd?<?0)
????{
????????printf("Open?Backlight?Device?Faild!\n");
????????exit(1);
????}
????
????//判斷輸入的參數
????if(strcmp(argv[1],?"on")?==?0)
????{
????????turn?=?1;
????}
????else?if(strcmp(argv[1],?"off")?==?0)
????{
????????turn?=?0;
????}
????else
????{
????????printf("Usage:?backlight?on|off!\n");
????????exit(1);
????}
????
????//進行IO控制
????ioctl(fd,?turn);

????//關閉背光設備
????close(fd);

????return?0;
}

?

編譯：arm-linux-gcc -o backlight_test backlight_test.c

?

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