系統大全為您提供開始學習驅動的時候，是將驅動程序編譯成模塊然后用mknod命令手動建立設備節點以提供給應用程序調用。這對于剛開始調試驅動程序的時候常用的一種方法。但是，當有種需要必須在系統啟動的時候就將驅動程序就緒，來供應用層程序調用。這時就不能再手動的建立設備節點了，而必須自動的創建設備節點（不需要人為的操作）。★注冊類注冊類的目的是為了使mdev可以在/dev/目錄下建立設備節點。首先要定義一個類，利用struct?class結構體。這個結構體定義在頭文件includenux/device.h中struct?class?{const?char*?name;struct?module*?owner;struct?subsystemsubsys;struct?list_headchildren;struct?list_headdevices;struct?list_headinterfaces;struct?semaphoresem;/*?locks?both?the?children?and?interfaces?lists?*/struct?kobject*virtual_dir;struct?class_attribute*?class_attrs;struct?class_device_attribute*?class_dev_attrs;struct?device_attribute*?dev_attrs;int(*uevent)(struct?class_device?*dev,?char?**envp,???int?num_envp,?char?*buffer,?int?buffer_size);int(*dev_uevent)(struct?device?*dev,?char?**envp,?int?num_envp,char?*buffer,?int?buffer_size);void(*release)(struct?class_device?*dev);void(*class_release)(struct?class?*class);void(*dev_release)(struct?device?*dev);int(*suspend)(struct?device?*,?pm_message_t?state);int(*resume)(struct?device?*);}?然后使用?完成對類的注冊。其中第一個參數一般為：THIS_MODULE。第二個參數為：設備節點的名稱舉個例子：★創建設備節點創建設備節點的函數：
struct?device?*device_create(struct?class?*class,?struct?device?*parent,dev_t?devt,?const?char?*fmt,?...){va_list?args;struct?device?*dev?=?NULL;int?retval?=?-ENODEV;if?(class?==?NULL?||?IS_ERR(class))goto?error;dev?=?kzalloc(sizeof(*dev),?GFP_KERNEL);if?(!dev)?{retval?=?-ENOMEM;goto?error;}dev->devt?=?devt;dev->class?=?class;dev->parent?=?parent;dev->release?=?device_create_release;va_start(args,?fmt);vsnprintf(dev->bus_id,?BUS_ID_SIZE,?fmt,?args);va_end(args);retval?=?device_register(dev);if?(retval)goto?error;return?dev;error:kfree(dev);return?ERR_PTR(retval);}該函數的四個參數從左到右以此為：創建設備節點所屬的類、該設備的父節點（若果沒有就指定為NULL）、設備號、設備名稱、次設備號。★銷毀類和設備節點注意不要忘記了還要銷毀類和銷毀設備節點。銷毀類：參數為用struct?class結構體定義的變量void?class_destroy(struct?class?*cls){if?((cls?==?NULL)?||?(IS_ERR(cls)))return;class_unregister(cls);}銷毀設備節點：void?device_destroy(struct?class?*class,?dev_t?devt){struct?device?*dev?=?NULL;struct?device?*dev_tmp;down(&class->sem);list_for_each_entry(dev_tmp,?&class->devices,?node)?{if?(dev_tmp->devt?==?devt)?{dev?=?dev_tmp;break;}}up(&class->sem);if?(dev)device_unregister(dev);}★例子（自己寫的延時驅動）#include?????#include?????#include?#include?????#include?#include?#include?#include?#include?#include?#include?#include?#include?#include?#include?#include?#include?#include?#include??#define?NAME"ralink_drive_delay"#define?RALINK_GPIO_DEVNAME?"my_delay"?#define?delay_us?0?????//most?least?is?10?US#define?delay_ms?1?????//Msint?delay_MAJOR?=?109;MODULE_LICENSE("Dual?BSD/GPL");static?long?Ralink_delay_ioctl(struct?inode?*?inode,?struct?file?*?file,?unsigned?int?cmd,unsigned?long?arg){????????switch(cmd)????{????????????case?delay_us:?????????????????udelay(10?*?arg);????????????????return?0;????????????case?delay_ms:????????????????udelay(1000);????????????????return?0;????????????default:????????????????return?-1;????}}static?struct?file_operations?My_delay_fops?=?{????.owner?=?THIS_MODULE,????.ioctl?=?Ralink_delay_ioctl,};static?struct?class?*delay_class;static?int?__init?my_delay_init(void){????int?ret?=?0;????ret?=?register_chrdev(delay_MAJOR,?RALINK_GPIO_DEVNAME,&My_delay_fops);????if(ret?
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