字符设备异步通知

driver:

#include   
#include   
#include   
#include   
#include   
#include 
 
#include   
#include   
  
struct fpga_key_dev  
{  
    struct cdev cdev;  
    dev_t devno;  
    char test[20];
    struct class *fpga_key_class; 
	struct fasync_struct *async_queue;

	int message_cdev_open;
};  
  
static int fpga_key_open(struct inode *node, struct file *fd)  
{  
	struct fpga_key_dev *dev;
	
	printk("fpga_key_open()++\n");  

	printk("node->i_cdev = %x\n", (unsigned int)node->i_cdev);
	dev = container_of(node->i_cdev, struct fpga_key_dev, cdev);
	printk("dev->cdev = %x\n", (unsigned int)&dev->cdev);
	printk("dev = %x\n", (unsigned int)dev);
	
	if (!dev->message_cdev_open) {
		dev->message_cdev_open = 1;
		fd->private_data = dev;
	}
	else{
		return -EFAULT;
	}
	
	printk("test[20] = %s\n",dev->test);
	
    printk("fpga_key_open()--\n");  
  
    return 0;  
}   
  
static ssize_t fpga_key_write(struct file *fd, const char __user *buf, size_t len, loff_t *ptr)  
{  
    char temp_buffer [20];  
    int print_size = 0;  
	struct fpga_key_dev *dev = fd->private_data;
      
    printk("fpga_key_wirte()++\n");  
    if(len > 20)  
        print_size = 20;  
    else  
        print_size = len;  
    printk("print_size = %d; len = %d\n", print_size, len);  
    if(copy_from_user(temp_buffer, buf, print_size))  
        return -EFAULT;  

	if (dev->async_queue)
		kill_fasync(&dev->async_queue, SIGIO, POLL_IN); 
	  
    printk("writing data:%s", temp_buffer);  
      
    printk("fpga_key_wirte()--\n");  
  
    return print_size;  
}  
static ssize_t fpga_key_read(struct file *fd, char __user *buf, size_t len, loff_t *ptr)  
{  
      char *temp_buffer = "Hello fpga_key_read !\n";  
      int print_size = 0;  
        
    printk("fpga_key_read()++\n");  
      
    if(len > strnlen(temp_buffer,20))  
        print_size = strnlen(temp_buffer,20);  
    else  
        print_size = len;  
    printk("print_size = %d; len = %d\n", print_size, len);  
    if(copy_to_user(buf, temp_buffer, print_size))  
        return -EFAULT;  
    printk("%s", temp_buffer);  
    printk("fpga_key_read()--\n");  
  
    return print_size;  
}  

static int fpga_key_fasync(int fd, struct file *filp, int mode)
{
	struct fpga_key_dev		*dev = filp->private_data;

	printk("fpga_key_fasync()++\n");
	
	fasync_helper(fd, filp, mode, &dev->async_queue); 

	printk("fpga_key_fasync()--\n");
	
	return 0;
}

static int fpga_key_release(struct inode *node, struct file *fd)  
{  
	struct fpga_key_dev *dev = fd->private_data;
	
	printk("fpga_key_release()++\n"); 

	dev->message_cdev_open = 0;
	fpga_key_fasync(-1, fd, 0);
	
    printk("fpga_key_release()--\n");  
    return 0;  
} 


struct file_operations meassage_operatons =  
{  
    .owner = THIS_MODULE,  
    .open = fpga_key_open,  
    .write = fpga_key_write,
    .read = fpga_key_read, 
    .fasync = fpga_key_fasync,
    .release = fpga_key_release,  
};  
  
struct fpga_key_dev fpga_key_dev;  
static int __init fpga_key_init(void)  
{  
    struct fpga_key_dev * dev;  
	char * temp_char = "hello world\n";
  
    printk("fpga_key_to_app_init(void)++\n");  
  
    dev = &fpga_key_dev;  
	strcpy(dev->test, temp_char);
	printk("%s",dev->test);
  
    alloc_chrdev_region(&dev->devno, 0, 1, "fpga_key_to_app");  
    //dev->cdev = cdev_alloc();  
    cdev_init(&dev->cdev, &meassage_operatons);  
    cdev_add(&dev->cdev, dev->devno, 1);  
    printk("dev->cdev = %x\n", (unsigned int)&dev->cdev);
	printk("dev = %x\n", (unsigned int)dev);
	
    dev->fpga_key_class = class_create(THIS_MODULE, "fpga_key_class");  
    if(IS_ERR(dev->fpga_key_class)) {  
         printk("Err: failed in creating class./n");  
         return -1;   
     }  
    device_create(dev->fpga_key_class, NULL, dev->devno, NULL, "fpga_key");  
    printk("fpga_key_to_app_init(void)--\n");      
    return 0;  
}  
static void __exit fpga_key_exit(void)  
{  
    struct fpga_key_dev *dev = &fpga_key_dev;  
  
    printk("fpga_key_to_app_exit(void)++\n");  
    device_destroy(dev->fpga_key_class, dev->devno);  
    class_destroy(dev->fpga_key_class);   
    cdev_del(&dev->cdev);  
    unregister_chrdev_region(dev->devno, 1);  
       
    printk("fpga_key_to_app_exit(void)--\n");  
}  
module_init(fpga_key_init);  
module_exit(fpga_key_exit);  
  
MODULE_LICENSE("GPL");  
MODULE_AUTHOR("Driver Monkey");  
MODULE_DESCRIPTION("Test fpga_key to App");  

App code:

#include  
#include  
#include  
#include  
#include  
#include  
#include  
#include  
  
unsigned int flag = 0;  
  
void sig_handler(int sig)  
{  
  printf("%s\n",__FUNCTION__);  
  flag++;  
}  
int main(void)  
{  
    char r_buf[20];  
    char *w_buf = "hello write!\n";  
    int r_count = 0;  
    int fd;  
    int f_flags;  
    flag++;  
    fd=open("/dev/fpga_key",O_RDWR);  
    if(fd<0)  
    {  
        perror("open");  
        return-1;  
    }  

    signal(SIGIO, sig_handler); 
    fcntl(fd, F_SETOWN, getpid());
    f_flags = fcntl(fd, F_GETFL);
    fcntl(fd, F_SETFL, FASYNC | f_flags); 
	
    while(1)
    {
	    printf("waiting \n"); 
	    sleep(2);
	    if(flag > 3)
		    break;
		printf("flag = %d\n", flag);
		
    	write(fd, w_buf, strlen(w_buf));  
    }       

    close(fd);  
  
    return 0;  
}