一個GPIO輸出高低電平的驅動源代碼

一個GPIO的驅動,輸出高低電平
驅動源代碼:GPIO_DRIVER.C
#include <linux/fs.h>
//#include <linux/iobuf.h>
#include <linux/major.h>
#include <linux/blkdev.h>
#include <linux/capability.h>
#include <linux/smp_lock.h>
#include <asm/uaccess.h>
#include <asm/hardware.h>
#include <asm/arch/AT91RM9200.h>
#include <linux/vmalloc.h>
#include <linux/delay.h>

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/config.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/sched.h>
#include <asm/io.h>
#include <asm/arch/gpio.h>
#include <linux/delay.h>

MODULE_LICENSE("GPL");

#define IOPORT_MAJOR 220 //定義主設備號

typedef char ioport_device_t;

static ioport_device_t gpio_devices[257];

#define IOWRITE                1;
#define IOCLEAR                2;

static int  gpio_open(struct inode *inode,struct file *filp)
{
        int minor;
        minor = MINOR(inode->i_rdev);

        at91_set_gpio_output(AT91_PIN_PB3,0 );
        gpio_devices[minor]++;
        return 0;
}

static int  gpio_release(struct inode *inode,struct file *filp)
{
        int minor;
        minor = MINOR(inode->i_rdev);
        if(gpio_devices[minor])
                gpio_devices[minor]--;
        return 0;
}

static int  gpio_ctl_ioctl(struct inode *inode, struct file *filp,

unsigned int command, unsigned long arg)
{
        int err = 0;
        int minor = MINOR(inode->i_rdev);
       
        switch(command)
        {
        case IOWRITE:
                err = at91_set_gpio_value(AT91_PIN_PB3,1);//輸出1高電平
                break;
        case IOCLEAR:
                err = at91_set_gpio_value(AT91_PIN_PB3,0);//輸出0低電平
                break;
}

        return err;
}

static struct file_operations gpio_ctl_fops={
    owner:                THIS_MODULE,
        ioctl:                gpio_ctl_ioctl,
        open:                gpio_open,
        release:        gpio_release,
};

static int __init gpio_init(void)
{
        register_chrdev(IOPORT_MAJOR ,"gpiotest",&gpio_ctl_fops);
        return 0;
}

static void __exit gpio_exit(void)
{
        unregister_chrdev(IOPORT_MAJOR,"gpiotest");
        return 0;
}

module_init(gpio_init);
module_exit(gpio_exit);
測試程序:
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#define DEVICE_GPIOTEST                "/dev/gpiotest"

#define IOWRITE                1;
#define IOCLEAR                2;

int main()
{
        int fd;
        int val=-1;
       
        if( (fd=open(DEVICE_GPIOTEST,O_WRITE | O_NONBLOCK)) < 0 )
        {
                perror("can not open device");
                exit(1);
        }
       
        while(1)
        {
                printf("0:set,1:clear,2:quit;");
                scanf("%d",&val);
               
                if(val==0)
                        ioctl(fd,IOWRITE,0);
                else if(val==1)
                        ioctl(fd,IOCLEAR,0);
                else if(val==2)
                  {
                        close(fd);
                        exit(1);
                }
        }
}
把生成的驅動.KO和交叉編譯的程序下載到板子的/tmp上,輸入0的時候是低電平,輸入1高電平。