デバイスドライバの基本関数

static ssize_t
xx_write(struct file * file, const char * buf,
                        size_t count, loff_t *ppos)

static ssize_t
xx_read(struct file * file, char * buf,
                       size_t count, loff_t *ppos)

static int
xx_open(struct inode * inode, struct file * file)

static int
xx_release(struct inode * inode, struct file * file)

static int
xx_ioctl(struct inode *inode, struct file *file,
                    unsigned int cmd, unsigned long arg)