Subversion Repositories shark

#ifndef _LINUX_TTY_LDISC_H
#define _LINUX_TTY_LDISC_H

/*
 * This structure defines the interface between the tty line discipline
 * implementation and the tty routines.  The following routines can be
 * defined; unless noted otherwise, they are optional, and can be
 * filled in with a null pointer.
 *
 * int  (*open)(struct tty_struct *);
 *
 *      This function is called when the line discipline is associated
 *      with the tty.  The line discipline can use this as an
 *      opportunity to initialize any state needed by the ldisc routines.
 *
 * void (*close)(struct tty_struct *);
 *
 *      This function is called when the line discipline is being
 *      shutdown, either because the tty is being closed or because
 *      the tty is being changed to use a new line discipline
 *
 * void (*flush_buffer)(struct tty_struct *tty);
 *
 *      This function instructs the line discipline to clear its
 *      buffers of any input characters it may have queued to be
 *      delivered to the user mode process.
 *
 * ssize_t (*chars_in_buffer)(struct tty_struct *tty);
 *
 *      This function returns the number of input characters the line
 *      discipline may have queued up to be delivered to the user mode
 *      process.
 *
 * ssize_t (*read)(struct tty_struct * tty, struct file * file,
 *                 unsigned char * buf, size_t nr);
 *
 *      This function is called when the user requests to read from
 *      the tty.  The line discipline will return whatever characters
 *      it has buffered up for the user.  If this function is not
 *      defined, the user will receive an EIO error.
 *
 * ssize_t (*write)(struct tty_struct * tty, struct file * file,
 *                  const unsigned char * buf, size_t nr);
 *
 *      This function is called when the user requests to write to the
 *      tty.  The line discipline will deliver the characters to the
 *      low-level tty device for transmission, optionally performing
 *      some processing on the characters first.  If this function is
 *      not defined, the user will receive an EIO error.
 *
 * int  (*ioctl)(struct tty_struct * tty, struct file * file,
 *               unsigned int cmd, unsigned long arg);
 *
 *      This function is called when the user requests an ioctl which
 *      is not handled by the tty layer or the low-level tty driver.
 *      It is intended for ioctls which affect line discpline
 *      operation.  Note that the search order for ioctls is (1) tty
 *      layer, (2) tty low-level driver, (3) line discpline.  So a
 *      low-level driver can "grab" an ioctl request before the line
 *      discpline has a chance to see it.
 *
 * void (*set_termios)(struct tty_struct *tty, struct termios * old);
 *
 *      This function notifies the line discpline that a change has
 *      been made to the termios structure.
 *
 * int  (*poll)(struct tty_struct * tty, struct file * file,
 *                poll_table *wait);
 *
 *      This function is called when a user attempts to select/poll on a
 *      tty device.  It is solely the responsibility of the line
 *      discipline to handle poll requests.
 *
 * void (*receive_buf)(struct tty_struct *, const unsigned char *cp,
 *                     char *fp, int count);
 *
 *      This function is called by the low-level tty driver to send
 *      characters received by the hardware to the line discpline for
 *      processing.  <cp> is a pointer to the buffer of input
 *      character received by the device.  <fp> is a pointer to a
 *      pointer of flag bytes which indicate whether a character was
 *      received with a parity error, etc.
 *
 * int  (*receive_room)(struct tty_struct *);
 *
 *      This function is called by the low-level tty driver to
 *      determine how many characters the line discpline can accept.
 *      The low-level driver must not send more characters than was
 *      indicated by receive_room, or the line discpline may drop
 *      those characters.
 *
 * void (*write_wakeup)(struct tty_struct *);
 *
 *      This function is called by the low-level tty driver to signal
 *      that line discpline should try to send more characters to the
 *      low-level driver for transmission.  If the line discpline does
 *      not have any more data to send, it can just return.
 */

#include <linux/fs.h>
#include <linux/wait.h>

struct tty_ldisc {
        int     magic;
        char    *name;
        int     num;
        int     flags;
       
        /*
         * The following routines are called from above.
         */
        int     (*open)(struct tty_struct *);
        void    (*close)(struct tty_struct *);
        void    (*flush_buffer)(struct tty_struct *tty);
        ssize_t (*chars_in_buffer)(struct tty_struct *tty);
        ssize_t (*read)(struct tty_struct * tty, struct file * file,
                        unsigned char * buf, size_t nr);
        ssize_t (*write)(struct tty_struct * tty, struct file * file,
                         const unsigned char * buf, size_t nr);
        int     (*ioctl)(struct tty_struct * tty, struct file * file,
                         unsigned int cmd, unsigned long arg);
        void    (*set_termios)(struct tty_struct *tty, struct termios * old);
        unsigned int (*poll)(struct tty_struct *, struct file *,
                             struct poll_table_struct *);
       
        /*
         * The following routines are called from below.
         */
        void    (*receive_buf)(struct tty_struct *, const unsigned char *cp,
                               char *fp, int count);
        int     (*receive_room)(struct tty_struct *);
        void    (*write_wakeup)(struct tty_struct *);

        struct  module *owner;
};

#define TTY_LDISC_MAGIC 0x5403

#define LDISC_FLAG_DEFINED      0x00000001

#define MODULE_ALIAS_LDISC(ldisc) \
        MODULE_ALIAS("tty-ldisc-" __stringify(ldisc))

#endif /* _LINUX_TTY_LDISC_H */