设备模型跟踪所有系统所知道的设备。进行跟踪的主要原因是让驱动程序协调与设备之间的关系。
先看驱动程序的结构体,仅仅贴出一些重要的成员:
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/*linux/device.h*/
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struct device_driver {
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const char *name; //驱动函数的名字,在对应总线的driver目录下显示
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struct bus_type *bus; //指定该驱动程序所操作的总线类型,必须设置,不然会注册失败
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struct module *owner;
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const char *mod_name; /* used for built-in modules */
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int (*probe) (struct device *dev); //探测函数,以后会讲
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int (*remove) (struct device *dev); //卸载函数,当设备从系统中删除时调用,以后讲
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void (*shutdown) (struct device *dev); //当系统关机是调用
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int (*suspend) (struct device *dev, pm_message_t state);
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int (*resume) (struct device *dev);
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struct attribute_group **groups;
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struct dev_pm_ops *pm;
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struct driver_private *p;
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};
驱动注册/注销
int driver_register(struct device_driver *drv) 注册驱动
void driver_unregister(struct device_driver *drv) 注销驱动
驱动属性
驱动的属性使用struct driver_attribute 来描述:
struct driver_attribute {
struct attribute attr;
ssize_t (*show)(struct device_driver *drv,char *buf);
ssize_t (*store)(struct device_driver *drv,const char *buf, size_t count);
}
int driver_create_file(struct device_driver * drv,struct driver_attribute * attr) 创建属性
void driver_remove_file(struct device_driver * drv,struct driver_attribute * attr) 删除属性
源码实例:
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#include <linux/device.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/string.h>
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extern struct bus_type my_bus_type;
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/*当驱动找到对应的设备时会执行该函数*/
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static int my_probe(struct device *dev)
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{
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printk("Driver found device which my driver can handle!\n");
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return 0;
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}
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static int my_remove(struct device *dev)
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{
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printk("Driver found device unpluged!\n");
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return 0;
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}
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struct device_driver my_driver = {
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.name = "my_dev",
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.bus = &my_bus_type,
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.probe = my_probe,
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.remove = my_remove,
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};
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static ssize_t mydriver_show(struct device_driver *driver, char *buf)
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{
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return sprintf(buf, "%s\n", "This is my driver!");
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}
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static DRIVER_ATTR(drv, S_IRUGO, mydriver_show, NULL);
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static int __init my_driver_init(void)
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{
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int ret = 0;
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/*注册驱动*/
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driver_register(&my_driver);
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/*创建属性文件*/
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driver_create_file(&my_driver, &driver_attr_drv);
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return ret;
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}
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static void my_driver_exit(void)
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{
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driver_unregister(&my_driver);
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}
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module_init(my_driver_init);
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module_exit(my_driver_exit);
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MODULE_AUTHOR("David Xie");
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MODULE_LICENSE("GPL");
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