gpio_driver.c

嵌入式LINUX的GPIO驱动和测试代码

//一个GPIO的驱动,输出高低电平
//驱动源代码: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 //定义主设备号

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);//输出1高电平
                break;
        case IOCLEAR:
                err = at91_set_gpio_value(AT91_PIN_PB3,0);//输出0低电平
                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);