请教关于并行端口驱动的问题？

w651134

1. 
   
2. 这是代码：
   
3. #include <linux/fs.h>
   
4. #include <linux/cdev.h>
   
5. #include <linux/parport.h>
   
6. #include <asm/uaccess.h>
   
7. #include <linux/platform_device.h>
   
8. #define DEVICE_NAME    "led1"
   
9. 
   
10. static dev_t dev_number;          /* Allotted device number */
    
11. static struct class *led_class;   /* Class to which this device
    
12.                                      belongs */
    
13. struct cdev led_cdev;             /* Associated cdev */
    
14. struct pardevice *pdev;           /* Parallel port device */
    
15. 
    
16. /* LED open */
    
17. int
    
18. led_open(struct inode *inode, struct file *file)
    
19. {
    
20.   return 0;
    
21. }
    
22. 
    
23. /* Write to the LED */
    
24. ssize_t
    
25. led_write(struct file *file, const char *buf,
    
26.           size_t count, loff_t *ppos)
    
27. {
    
28.   char kbuf;
    
29.   if (copy_from_user(&kbuf, buf, 1)) return -EFAULT;
    
30.   /* Claim the port */
    
31. 
    
32.    parport_claim_or_block(pdev);
    
33.   /* Write to the device */
    
34.    parport_write_data(pdev->port, kbuf);
    
35.   /* Release the port */
    
36.   parport_release(pdev);
    
37.   return count;
    
38. }
    
39. /* Release the device */
    
40. int
    
41. led_release(struct inode *inode, struct file *file)
    
42. {
    
43.   return 0;
    
44. }
    
45. 
    
46. /* File Operations */
    
47. static struct file_operations led_fops = {
    
48.   .owner = THIS_MODULE,
    
49.   .open = led_open,
    
50.   .write = led_write,
    
51.   .release = led_release,
    
52. };
    
53. /*
    
54. static int
    
55. led_preempt(void *handle)
    
56. {
    
57.   return 1;
    
58. }
    
59. */
    
60. /* Parport attach method */
    
61. static void
    
62. led_attach(struct parport *port)
    
63. {
    
64.   /* Register the parallel LED device with parport */
    
65.   pdev = parport_register_device(port, DEVICE_NAME,
    
66.                                  NULL, NULL,
    
67.                                  NULL, 0, NULL);
    
68.   if (pdev == NULL) printk("Bad register\n");
    
69. else
    
70. printk("well register\n");
    
71. }
    
72. 
    
73. /* Parport detach method */
    
74. static void
    
75. led_detach(struct parport *port)
    
76. {
    
77.   /* Do nothing */
    
78. }
    
79. 
    
80. /* Parport driver operations */
    
81. static struct parport_driver led_driver = {
    
82.   .name   = "led1",
    
83.   .attach = led_attach,
    
84.   .detach = led_detach,
    
85. };
    
86. /* Driver Initialization */
    
87. int __init
    
88. led_init(void)
    
89. {
    
90.   /* Request dynamic allocation of a device major number */
    
91.   if (alloc_chrdev_region(&dev_number, 0, 1, DEVICE_NAME)
    
92.                           < 0) {
    
93.     printk(KERN_DEBUG "Can't register device\n");
    
94.     return -1;
    
95.   }
    
96.   /* Create the led class */
    
97.   led_class = class_create(THIS_MODULE, DEVICE_NAME);
    
98.   if (IS_ERR(led_class)) printk("Bad class create\n");
    
99. 
    
100.   /* Connect the file operations with the cdev */
     
101.   cdev_init(&led_cdev, &led_fops);
     
102. 
     
103.   led_cdev.owner = THIS_MODULE;
     
104. 
     
105.   /* Connect the major/minor number to the cdev */
     
106.   if (cdev_add(&led_cdev, dev_number, 1)) {
     
107.     printk("Bad cdev add\n");
     
108.     return 1;
     
109.   }
     
110. 
     
111. 
     
112.   class_device_create(led_class, NULL, dev_number,
     
113.                                  NULL, DEVICE_NAME);
     
114.   /* Register this driver with parport */
     
115.   if (parport_register_driver(&led_driver)) {
     
116.     printk(KERN_ERR "Bad Parport Register\n");
     
117.     return -EIO;
     
118.   }
     
119. 
     
120.   printk("LED Driver Initialized.\n");
     
121.   return 0;
     
122. }
     
123. 
     
124. /* Driver Exit */
     
125. void __exit
     
126. led_cleanup(void)
     
127. {
     
128.   unregister_chrdev_region(MAJOR(dev_number), 1);
     
129.   class_device_destroy(led_class, MKDEV(MAJOR(dev_number), 0));
     
130.   class_destroy(led_class);
     
131.   return;
     
132. }
     
133. 
     
134. module_init(led_init);
     
135. module_exit(led_cleanup);
     
136. 
     
137. MODULE_LICENSE("GPL");

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