字符设备学习2

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

static struct class *firstdrv_class;
static struct class_device *firstdrv_class_dev;

volatile unsigned long *gdfcon = NULL;
volatile unsigned long *gdfdat = NULL;
static int first_drv_open(struct inode *inode, struct file *file)
{
    *gdfcon &= ~((0x3 <<(4*2)) | (0x3 <<(5*2)) |( 0x3 << (6*2)));
    *gdfcon |= ((0x1<<(4*2)) | (0x1 <<(5*2)) | (0x1 << (6*2)));  // 设置引脚输出
    return 0;
}
static ssize_t first_drv_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
    int val;
    copy_from_user(&val,buf,count);  //copy_to_user()
    if(val == 1)
    {
    //点灯

    *gdfdat &= ~((1<<4) | (1<<5) | (1<<6));
    }
    else
    {
    //关灯
    *gdfdat  |= ((1<<4) | (1<<5) | (1<<6));
    }
    return 0;
}


static struct file_operations first_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   =   first_drv_open,     
.write = first_drv_write,   
};




int major;
static int first_drv_init(void)
{
    major = register_chrdev(0, "first_drv", &first_drv_fops); // 注册, 告诉内核
    firstdrv_class = class_create(THIS_MODULE, "firstdrv");
    firstdrv_class_dev = class_device_create(firstdrv_class, NULL, MKDEV(major, 0), NULL, "xyz"); /* /dev/xyz */
    gdfcon =(volatile unsigned long*)ioremap(0x56000050,16);
    gdfdat = gdfcon +1;
    return 0;
}


static void first_drv_exit(void)
{
    unregister_chrdev(major, "first_drv"); // 卸载
    class_device_unregister(firstdrv_class_dev);
    class_destroy(firstdrv_class);
    iounmap(gdfcon);

}

module_init(first_drv_init);
module_exit(first_drv_exit);

MODULE_LICENSE("GPL");

1 . 物理地址与虚拟地址映射
      gdfcon =(volatile unsigned long*)ioremap(0x56000050,16);
测试函数：

#include
#include   
#include    
#include
int main(int argc,char **argv)
{
int fd = open("/dev/xyz",O_RDWR);
int val;
if(argc != 2)
{
printf(" please entery ./main on or off\n");
return -1;
}
if(strcmp(argv[1],"on") == 0)
{
val = 1;
}
else
{
val = 0;
}
write(fd,&val,4);
close(fd);
}