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