用一个.c文件来理解bus,driver,device,sysfs的关系和driver&device的bind过程

Question

忙了一个下午，调成功了一个module.写出来可能对驱动新手有一定帮助。我本人就是新手，所以从源码中理解这些概念花了一定的功夫。
以下module可以验证device,driver,bus的关系及在sysfs的体系，及bus先match，driver再probe的过程。
同时追求代码最小化，可见bus,device,driver等对象在注册时哪些信息是必须的。

1. #include <linux/module.h>
2. #include <linux/kobject.h>
3. #include <linux/device.h>
5. /*未实现设备文件创建和文件系统驱动*/
7. static int my_bus_match(struct device* device, struct device_driver* driver);
8. static int my_driver_probe(struct device* dev);
9. static void unregister_all(void);
10. static int register_all(void);
12. MODULE_LICENSE("GPL");
14. struct bus_type my_bus_type =
15. {
16.   .name = "my_bus_type",
17.   .match= my_bus_match
18. };
20. struct my_device
21. {
22.   int id;
23.   struct device dev;
24.   int drv_id;
25. };
27. struct my_device_driver
28. {
29. int id;
30. struct device_driver drv;
31. };
33. struct my_device_driver my_driver_1 =
34. {
35.   .drv =
36.   {
37.     .name = "my_bus_driver_1",
38.     .probe = my_driver_probe,
39.     .bus = &my_bus_type,
40.   },
41.   .id = 1,
42. };
43. struct my_device_driver my_driver_2 =
44. {
45.   .drv =
46.   {
47.     .name = "my_bus_driver_2",
48.     .probe = my_driver_probe,
49.     .bus = &my_bus_type
50.   },
51.   .id = 2
52. };
54. struct my_device my_device_1 =
55. {
56.   .id=001,
57.   .drv_id = 1,
58.   .dev =
59.   {
60.     .bus = &my_bus_type,   
61.     .bus_id = "my_bus_id_1"
62.   }
63.   
64. };
65. struct my_device my_device_2 =
66. {
67.   .id=002,
68.   .drv_id = 2,
69.   .dev =
70.   {
71.     .bus = &my_bus_type,
72.     .bus_id = "my_bus_id_2"
73.   }
74. };
77. static int device_match_driver(struct my_device* mydev, struct my_device_driver* mydrv)
78. {
79.   printk("one match tested: dev_id=%d, dev.drv_id=%d, drv_id=%d, drv_name=%s\n", mydev->id,
80.          mydev->drv_id, mydrv->id, mydrv->drv.name );
81.   if(mydev->drv_id != mydrv->id)
82.        return 0;
83.   return 1;
84. }
86. static int my_bus_match(struct device* device, struct device_driver* driver)
87. {
88.   struct my_device* mydev = container_of(device, struct  my_device, dev);
89.   struct my_device_driver* mydrv = container_of(driver, struct my_device_driver, drv);
90.   printk("my_bus_match called\n");
91.   if(device_match_driver(mydev, mydrv))
92.   {
93.         printk("one matched group:dev_id=%d drv_id=%d\n", mydev->id, mydrv->id);
94.         return 1;
95.   }
96.   printk("device %d and driver %d not match\n", mydev->id, mydrv->id);
97.   return 0;
98. }
100. static int my_driver_probe(struct device* dev)
101. {
102.   struct my_device_driver* mydrv = container_of(dev->driver, struct my_device_driver, drv);
103.   struct my_device* mydev = container_of(dev, struct my_device, dev);
104.   printk("my_driver %s drive probe called\n", mydrv->drv.name);
105.   if(device_match_driver(mydev, mydrv))
106.       return 0;
107.   return 1;
108. }
109. const int errExist = -17;
110. int bus_is_registered = 0;
111. static int register_all()
112. {
113.   int res;
114.   res = bus_register(&my_bus_type);
115.   if(res)
116.   {
117.      printk("register my_bus_type failed\n");
118.      return res;
119.   }
121.   bus_is_registered = 1;
123.    /*register driver 1*/
124.    res = driver_register(&my_driver_1.drv);
125.    if(res)
126.    {
127.       printk("register my_driver_1 failed\n");
128.       return res;
129.    }
130.        
131.    /*register driver 2*/
132.    res  = driver_register(&my_driver_2.drv);  
133.    if(res)
134.    {
135.       printk("register my_driver_2 failed\n");
136.       return res;
137.    }
138.    
139.    /*add device 1*/
140.    res = device_register(&my_device_1.dev);
141.    if(res)
142.    {
143.      printk("register my_device_1 failed\n");
144.      return res;
145.    }
146.    res = device_register(&my_device_2.dev);
147.    if(res)
148.    {
149.      printk("register my_device_2 failed\n");
150.      return res;
151.    }
152.    return 0;
153. }
155. static int my_init(void)
156. {
157.   int res;
158.   printk("my_init called\n");
159.   if((res = register_all()))
160.   {
161.     if(res != errExist && bus_is_registered)
162.        bus_unregister(&my_bus_type);
163.   /* dangerous if call unregister_all();*/
164.         printk("res=%d\n",res);
166.     return res;
167.   }
168.   return 0;
169. }
171. static void unregister_all()
172. {
173. device_unregister(&my_device_1.dev);
174. device_unregister(&my_device_2.dev);
175. driver_unregister(&my_driver_1.drv);
176. driver_unregister(&my_driver_2.drv);
177. bus_unregister(&my_bus_type);
178. }
180. static void my_exit(void)
181. {
182. unregister_all();
183. }
185. module_init(my_init);
186. module_exit(my_exit);

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Answer 1

:wink:
LDD 里面讲得也不错~