嵌入式实践教程--设备树下的platform驱动

1 struct bus_type platform_bus_type = { 
2   .name = "platform", 
3   .dev_groups = platform_dev_groups,
4   .match = platform_match, 
5   .uevent = platform_uevent, 
6   .pm = &platform_dev_pm_ops, 
 };

1 static int platform_match(struct device *dev,
struct device_driver *drv)
2 { 3 struct platform_device *pdev = to_platform_device(dev);
4 struct platform_driver *pdrv = to_platform_driver(drv);
5 
6 /*When driver_override is set,only bind to the matching driver*/
7 if (pdev->driver_override) 8 return !strcmp(pdev->driver_override, drv->name);
9 
10 /* Attempt an OF style match first */
11 if (of_driver_match_device(dev, drv))
12 return 1;
13
14 /* Then try ACPI style match */
15 if (acpi_driver_match_device(dev, drv))
16 return 1;
17
18 /* Then try to match against the id table */
19 if (pdrv->id_table)
20 return platform_match_id(pdrv->id_table, pdev) != NULL;
21
22 /* fall-back to driver name match */
23 return (strcmp(pdev->name, drv->name) == 0);
24 }

platform 驱动框架如下所示：
示例代码 54.2.2.5 platform 驱动框架
/* 设备结构体 */
1 struct xxx_dev{ 2 struct cdev cdev; 3 /* 设备结构体其他具体内容 */
4 };
5 
6 struct xxx_dev xxxdev; /* 定义个设备结构体变量 */
7 
8 static int xxx_open(struct inode *inode, struct file *filp) 9 { 
10 /* 函数具体内容 */
11 return 0;
12 }
13
14 static ssize_t xxx_write(struct file *filp, const char __user *buf,
size_t cnt, loff_t *offt)
15 {
16 /* 函数具体内容 */
17 return 0;
18 }
19
20 /*
21 * 字符设备驱动操作集
22 */
23 static struct file_operations xxx_fops = {
24 .owner = THIS_MODULE,
25 .open = xxx_open,
26 .write = xxx_write,
27 };
28
29 /*
30 * platform 驱动的 probe 函数
31 * 驱动与设备匹配成功以后此函数就会执行
32 */
33 static int xxx_probe(struct platform_device *dev)
34 { 
35 ......
36 cdev_init(&xxxdev.cdev, &xxx_fops); /* 注册字符设备驱动 */
37 /* 函数具体内容 */
38 return 0;
39 }
40
41 static int xxx_remove(struct platform_device *dev)
42 {
43 ......
44 cdev_del(&xxxdev.cdev);/* 删除 cdev */
45 /* 函数具体内容 */
46 return 0;
47 }
48
49 /* 匹配列表 */
50 static const struct of_device_id xxx_of_match[] = {
51 { .compatible = "xxx-gpio" },
52 { /* Sentinel */ }
53 };
54
55 /* 
56 * platform 平台驱动结构体
57 */
58 static struct platform_driver xxx_driver = {
59 .driver = {
60 .name = "xxx",
61 .of_match_table = xxx_of_match,
62 },
63 .probe = xxx_probe,
64 .remove = xxx_remove,
65 };
66 
67 /* 驱动模块加载 */
68 static int __init xxxdriver_init(void)
69 {
70 return platform_driver_register(&xxx_driver);
71 }
72
73 /* 驱动模块卸载 */
74 static void __exit xxxdriver_exit(void)
75 {
76 platform_driver_unregister(&xxx_driver);
77 }
78
79 module_init(xxxdriver_init);
80 module_exit(xxxdriver_exit);
81 MODULE_LICENSE("GPL");
82 MODULE_AUTHOR("zuozhongkai")