LINUX系统下的设备驱动程序
具体到LINUX系统里，设备驱动程序所提供的这组入口点由一个结构来向系统进行说明，此结构定义为：
#include
struct file_operations {
int (*lseek)(struct inode *inode,struct file *filp,
off_t off,int pos);
int (*read)(struct inode *inode,struct file *filp,
char *buf, int count);
int (*write)(struct inode *inode,struct file *filp,
char *buf,int count);
int (*readdir)(struct inode *inode,struct file *filp,
struct dirent *dirent,int count);
int (*select)(struct inode *inode,struct file *filp,
int sel_type,select_table *wait);
int (*ioctl) (struct inode *inode,struct file *filp,
unsigned int cmd,unsigned int arg);
int (*mmap) (void);
int (*open) (struct inode *inode, struct file *filp);
void (*release) (struct inode *inode, struct file *filp);
int (*fsync) (struct inode *inode, struct file *filp);
};
其中，struct inode提供了关于特别设备文件/dev/driver（假设此设备名为driver）的信息，它的定义为：
#include
struct inode {
dev_t i_dev;
unsigned long i_ino; /* Inode number */
umode_t i_mode; /* Mode of the file */
nlink_t i_nlink;
uid_t i_uid;
gid_t i_gid;
dev_t i_rdev; /* Device major and minor numbers*/
off_t i_size;
time_t i_atime;
time_t i_mtime;
time_t i_ctime;
unsigned long i_blksize;
unsigned long i_blocks;
struct inode_operations * i_op;
struct super_block * i_sb;
struct wait_queue * i_wait;
struct file_lock * i_flock;
struct vm_area_struct * i_mmap;
struct inode * i_next, * i_prev;
struct inode * i_hash_next, * i_hash_prev;
struct inode * i_bound_to, * i_bound_by;
unsigned short i_count;
unsigned short i_flags; /* Mount flags (see fs.h) */
unsigned char i_lock;
unsigned char i_dirt;
unsigned char i_pipe;
unsigned char i_mount;
unsigned char i_seek;
unsigned char i_update;
union {
struct pipe_inode_info pipe_i;
struct minix_inode_info minix_i;
struct ext_inode_info ext_i;
struct msdos_inode_info msdos_i;
struct iso_inode_info isofs_i;
struct nfs_inode_info nfs_i;
} u;
};
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