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#ifndef _LINUX_TTY_DRIVER_H

#define _LINUX_TTY_DRIVER_H

/*

 * This structure defines the interface between the low-level tty

 * driver 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 * tty, struct file * filp);

 *

 *      This routine is called when a particular tty device is opened.

 *      This routine is mandatory; if this routine is not filled in,

 *      the attempted open will fail with ENODEV.

 *

 * void (*close)(struct tty_struct * tty, struct file * filp);

 *

 *      This routine is called when a particular tty device is closed.

 *

 * int (*write)(struct tty_struct * tty, int from_user,

 *               const unsigned char *buf, int count);

 *

 *      This routine is called by the kernel to write a series of

 *      characters to the tty device.  The characters may come from

 *      user space or kernel space.  This routine will return the

 *      number of characters actually accepted for writing.  This

 *      routine is mandatory.

 *

 * void (*put_char)(struct tty_struct *tty, unsigned char ch);

 *

 *      This routine is called by the kernel to write a single

 *      character to the tty device.  If the kernel uses this routine,

 *      it must call the flush_chars() routine (if defined) when it is

 *      done stuffing characters into the driver.  If there is no room

 *      in the queue, the character is ignored.

 *

 * void (*flush_chars)(struct tty_struct *tty);

 *

 *      This routine is called by the kernel after it has written a

 *      series of characters to the tty device using put_char().

 *

 * int  (*write_room)(struct tty_struct *tty);

 *

 *      This routine returns the numbers of characters the tty driver

 *      will accept for queuing to be written.  This number is subject

 *      to change as output buffers get emptied, or if the output flow

 *      control is acted.

 *

 * int  (*ioctl)(struct tty_struct *tty, struct file * file,

 *          unsigned int cmd, unsigned long arg);

 *

 *      This routine allows the tty driver to implement

 *      device-specific ioctl's.  If the ioctl number passed in cmd

 *      is not recognized by the driver, it should return ENOIOCTLCMD.

 *

 * void (*set_termios)(struct tty_struct *tty, struct termios * old);

 *

 *      This routine allows the tty driver to be notified when

 *      device's termios settings have changed.  Note that a

 *      well-designed tty driver should be prepared to accept the case

 *      where old == NULL, and try to do something rational.

 *

 * void (*set_ldisc)(struct tty_struct *tty);

 *

 *      This routine allows the tty driver to be notified when the

 *      device's termios settings have changed.

 *

 * void (*throttle)(struct tty_struct * tty);

 *

 *      This routine notifies the tty driver that input buffers for

 *      the line discipline are close to full, and it should somehow

 *      signal that no more characters should be sent to the tty.

 *

 * void (*unthrottle)(struct tty_struct * tty);

 *

 *      This routine notifies the tty drivers that it should signals

 *      that characters can now be sent to the tty without fear of

 *      overrunning the input buffers of the line disciplines.

 *

 * void (*stop)(struct tty_struct *tty);

 *

 *      This routine notifies the tty driver that it should stop

 *      outputting characters to the tty device.

 *

 * void (*start)(struct tty_struct *tty);

 *

 *      This routine notifies the tty driver that it resume sending

 *      characters to the tty device.

 *

 * void (*hangup)(struct tty_struct *tty);

 *

 *      This routine notifies the tty driver that it should hangup the

 *      tty device.

 *

 */

#include <linux/fs.h>

struct tty_driver {

        int     magic;          /* magic number for this structure */

        const char      *name;

        int     name_base;      /* offset of printed name */

        short   major;          /* major device number */

        short   minor_start;    /* start of minor device number*/

        short   num;            /* number of devices */

        short   type;           /* type of tty driver */

        short   subtype;        /* subtype of tty driver */

        struct termios init_termios; /* Initial termios */

        int     flags;          /* tty driver flags */

        int     *refcount;      /* for loadable tty drivers */

        struct tty_driver *other; /* only used for the PTY driver */

        /*

         * Pointer to the tty data structures

         */

        struct tty_struct **table;

        struct termios **termios;

        struct termios **termios_locked;

        /*

         * Interface routines from the upper tty layer to the tty

         * driver.

         */

        int  (*open)(struct tty_struct * tty, struct file * filp);

        void (*close)(struct tty_struct * tty, struct file * filp);

        int  (*write)(struct tty_struct * tty, int from_user,

                      const unsigned char *buf, int count);

        void (*put_char)(struct tty_struct *tty, unsigned char ch);

        void (*flush_chars)(struct tty_struct *tty);

        int  (*write_room)(struct tty_struct *tty);

        int  (*chars_in_buffer)(struct tty_struct *tty);

        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);

        void (*throttle)(struct tty_struct * tty);

        void (*unthrottle)(struct tty_struct * tty);

        void (*stop)(struct tty_struct *tty);

        void (*start)(struct tty_struct *tty);

        void (*hangup)(struct tty_struct *tty);

        void (*flush_buffer)(struct tty_struct *tty);

        void (*set_ldisc)(struct tty_struct *tty);

        /*

         * linked list pointers

         */

        struct tty_driver *next;

        struct tty_driver *prev;

};

/* tty driver magic number */

#define TTY_DRIVER_MAGIC                0x5402

/*

 * tty driver flags

 *

 * TTY_DRIVER_RESET_TERMIOS --- requests the tty layer to reset the

 *      termios setting when the last process has closed the device.

 *      Used for PTY's, in particular.

 *

 * TTY_DRIVER_REAL_RAW --- if set, indicates that the driver will

 *      guarantee never not to set any special character handling

 *      flags if ((IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR ||

 *      !INPCK)).  That is, if there is no reason for the driver to

 *      send notifications of parity and break characters up to the

 *      line driver, it won't do so.  This allows the line driver to

 *      optimize for this case if this flag is set.  (Note that there

 *      is also a promise, if the above case is true, not to signal

 *      overruns, either.)

 */

#define TTY_DRIVER_INSTALLED            0x0001

#define TTY_DRIVER_RESET_TERMIOS        0x0002

#define TTY_DRIVER_REAL_RAW             0x0004

/* tty driver types */

#define TTY_DRIVER_TYPE_SYSTEM          0x0001

#define TTY_DRIVER_TYPE_CONSOLE         0x0002

#define TTY_DRIVER_TYPE_SERIAL          0x0003

#define TTY_DRIVER_TYPE_PTY             0x0004

#define TTY_DRIVER_TYPE_SCC             0x0005  /* scc driver */

/* system subtypes (magic, used by tty_io.c) */

#define SYSTEM_TYPE_TTY                 0x0001

#define SYSTEM_TYPE_CONSOLE             0x0002

/* pty subtypes (magic, used by tty_io.c) */

#define PTY_TYPE_MASTER                 0x0001

#define PTY_TYPE_SLAVE                  0x0002

#endif /* #ifdef _LINUX_TTY_DRIVER_H */