字符设备驱动笔记——查询方式按键驱动（三）

second_drv.c

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/fs.h>

#include <linux/init.h>

#include <linux/delay.h>

#include <asm/uaccess.h>

#include <asm/irq.h>

#include <asm/io.h>

#include <asm/arch/regs-gpio.h>

#include <asm/hardware.h>



static struct class *seconddrv_class;

static struct class_device    *seconddrv_class_dev;



volatile unsigned long *gpfcon;

volatile unsigned long *gpfdat;



volatile unsigned long *gpgcon;

volatile unsigned long *gpgdat;



static int second_drv_open(struct inode *inode, struct file *file)

{

    /* 配置GPF0,2为输入引脚 */

    *gpfcon &= ~((0x3<<(0*2)) | (0x3<<(2*2)));



    /* 配置GPG3,11为输入引脚 */

    *gpgcon &= ~((0x3<<(3*2)) | (0x3<<(11*2)));



    return 0;

}



ssize_t second_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)

{

    /* 返回4个引脚的电平 */

    unsigned char key_vals[4];

    int regval;



    if (size != sizeof(key_vals))

        return -EINVAL;



    /* 读GPF0,2 */

    regval = *gpfdat;

    key_vals[0] = (regval & (1<<0)) ? 1 : 0;

    key_vals[1] = (regval & (1<<2)) ? 1 : 0;

    



    /* 读GPG3,11 */

    regval = *gpgdat;

    key_vals[2] = (regval & (1<<3)) ? 1 : 0;

    key_vals[3] = (regval & (1<<11)) ? 1 : 0;



    copy_to_user(buf, key_vals, sizeof(key_vals));

    

    return sizeof(key_vals);

}





static struct file_operations sencod_drv_fops = {

    .owner  =   THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */

    .open   =   second_drv_open,     

    .read    =    second_drv_read,       

};





int major;

static int second_drv_init(void)

{

    //注册

    major = register_chrdev(0, "second_drv", &sencod_drv_fops);



    //udev  mdev是udev的一个简化版本

    seconddrv_class = class_create(THIS_MODULE, "second_drv");

    seconddrv_class_dev = class_device_create(seconddrv_class, NULL, MKDEV(major, 0), NULL, "buttons"); /* /dev/buttons */



    gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);

    gpfdat = gpfcon + 1;



    gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);

    gpgdat = gpgcon + 1;



    return 0;

}



static void second_drv_exit(void)

{

    unregister_chrdev(major, "second_drv");



    class_device_unregister(seconddrv_class_dev);

    class_destroy(seconddrv_class);



    iounmap(gpfcon);

    iounmap(gpgcon);

}



module_init(second_drv_init);

module_exit(second_drv_exit);



MODULE_LICENSE("GPL");

seconddrvtest.c

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <stdio.h>



/* seconddrvtest 

  */

int main(int argc, char **argv)

{

    int fd;

    unsigned char key_vals[4];

    int cnt = 0;

    

    fd = open("/dev/buttons", O_RDWR);

    if (fd < 0)

    {

        printf("can't open!\n");

    }



    while (1)

    {

        read(fd, key_vals, sizeof(key_vals));

        if (!key_vals[0] || !key_vals[1] || !key_vals[2] || !key_vals[3])

        {

            printf("%04d key pressed: %d %d %d %d\n", cnt++, key_vals[0], key_vals[1], key_vals[2], key_vals[3]);

        }

    }

    

    return 0;

}

Makefile

KERN_DIR = /work/system/linux-2.6.22.6



all:

    make -C $(KERN_DIR) M=`pwd` modules 



clean:

    make -C $(KERN_DIR) M=`pwd` modules clean

    rm -rf modules.order



obj-m    += second_drv.o