嵌入式Linux之我行——LCD背光驱动在2440上的实例开发

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

#include
#include
#include
#include
#include
#include
#include

#defineDEVICE_NAME"backlight"//设备名称
#defineDEVICE_MINOR5//次设备号，这里我们将设备注册为misc设备，这种设备的主设备号都为10

staticintmy2440_backlight_ioctl(structinode*inode,

structfile*file,

unsignedintcmd,

unsignedlongarg)
{
switch(cmd)
{
case0:

//当接收的命令为0时，就将GPG4引脚设为低电平，关闭背光
s3c2410_gpio_setpin(S3C2410_GPG4,0);
printk(DEVICE_NAME" turn off!n");
return0;
case1:

//当接收的命令为1时，就将GPG4引脚设为高电平，开启背光
s3c2410_gpio_setpin(S3C2410_GPG4,1);
printk(DEVICE_NAME" turn on!n");
return0;
default:
return-EINVAL;
}
}

staticstructfile_operations dev_fops=
{
.owner=THIS_MODULE,
.ioctl=my2440_backlight_ioctl,//这里只使用控制IO口的方式来控制背光
};

staticstructmiscdevice misc=
{
.minor=DEVICE_MINOR,
.name=DEVICE_NAME,
.fops=&dev_fops,
};

staticint__init dev_init(void)
{
intret;

ret=misc_register(&misc);//注册成misc设备

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

//将GPG4口配置成输出口
s3c2410_gpio_cfgpin(S3C2410_GPG4,S3C2410_GPG4_OUTP);

returnret;
}

staticvoid__exit dev_exit(void)
{
misc_deregister(&misc);//注销该misc设备
}

module_init(dev_init);
module_exit(dev_exit);

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

#cp -f my2440_backlight.c linux-2.6.30.4/drivers/video/backlight/

#gedit linux-2.6.30.4/drivers/video/backlight/Kconfig

configMY2440_LCD_BACKLIGHT
tristate"My2440 LCD Backlight Controls"
dependsonBACKLIGHT_LCD_SUPPORT
default y

#gedit linux-2.6.30.4/drivers/video/backlight/Makefile

obj-$(CONFIG_MY2440_LCD_BACKLIGHT)+=my2440_backlight.o

Device Drivers --->
Graphics support --->
[*] Backlight & LCD device support --->
--- Backlight & LCD device support
<*> My2440 LCD Backlight Controls (NEW)
< > Lowlevel LCD controls
< > Lowlevel Backlight controls

#mknod /dev/backlight c 10 5

#include
#include
#include
#include

intmain(intargc,char**argv)
{
intturn;
intfd;

//检测命令后面带的参数
if(argc==1||argc>2)
{
printf("Usage: backlight on|off!n");
exit(1);
}

//打开背光设备
fd=open("/dev/backlight",O_RDWR);

if(fd<0)
{
printf("Open Backlight Device Faild!n");
exit(1);
}

//判断输入的参数
if(strcmp(argv[1],"on")==0)
{
turn=1;
}
elseif(strcmp(argv[1],"off")==0)
{
turn=0;
}
else
{
printf("Usage: backlight on|off!n");
exit(1);
}

//进行IO控制
ioctl(fd,turn);

//关闭背光设备
close(fd);

return0;
}

#arm-linux-gcc -o backlight_test backlight_test.c