chardev.h

这是一个我经过研究学习,理解了别人得程序,感觉很不错的源程序.

#ifndef CHARDEV_H
#define CHARDEV_H

#include <linux/ioctl.h>
#include "sysdep.h"

#undef PDEBUG
#ifdef CHARDEV_DEBUG
#  ifdef __KERNEL__
#    define PDEBUG(fmt,args...) printk(KERNEL_DEBUG "mychardev:" fmt, ##args)
#  else
#    define PDEBUG(fmt,args...) fprintf(stderr,fmt,##args)
#  endif
#else
#  define PDEBUG(fmt,args...) /* nothing */
#endif

#undef PDEBUGG
#define PDEBUGG(fmt,args...)  /* nothing */

#ifndef CHARDEV_MAJOR
#define CHARDEV_MAJOR 0       /* dynamic major by default */
#endif

#ifndef CHARDEV_BUFLEN
#define CHARDEV_BUFLEN 4000
#endif

typedef struct CHAR_DEV {
  char *data;
  struct semaphore sem;
} CHAR_DEV;

extern int chardev_major;
extern long chardev_buflen;

extern int chardev_trim(CHAR_DEV *dev);
extern int chardev_init_module(void);
extern void chardev_cleanup_module(void);

extern int chardev_open(struct inode *inode, struct file *filp);
extern int chardev_release(struct inode *inode, struct file *filp);
extern ssize_t chardev_read(struct file *filp, char *buf, size_t count, loff_t *f_pos);
extern ssize_t chardev_write(struct file *filp, const char *buf, size_t count, loff_t *f_pos);
#endif