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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.
 *
 * void (*break_ctl)(struct tty_stuct *tty, int state);
 *
 *      This optional routine requests the tty driver to turn on or
 *      off BREAK status on the RS-232 port.  If state is -1,
 *      then the BREAK status should be turned on; if state is 0, then
 *      BREAK should be turned off.
 *
 *      If this routine is implemented, the high-level tty driver will
 *      handle the following ioctls: TCSBRK, TCSBRKP, TIOCSBRK,
 *      TIOCCBRK.  Otherwise, these ioctls will be passed down to the
 *      driver to handle.
 *
 * void (*wait_until_sent)(struct tty_struct *tty, int timeout);
 *
 *      This routine waits until the device has written out all of the
 *      characters in its transmitter FIFO.
 *
 * void (*send_xchar)(struct tty_struct *tty, char ch);
 *
 *      This routine is used to send a high-priority XON/XOFF
 *      character to the device.
 */


#include <linux/fs.h>
#include <linux/list.h>
#include <linux/cdev.h>

struct tty_struct;

struct tty_operations {
        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 (*break_ctl)(struct tty_struct *tty, int state);
        void (*flush_buffer)(struct tty_struct *tty);
        void (*set_ldisc)(struct tty_struct *tty);
        void (*wait_until_sent)(struct tty_struct *tty, int timeout);
        void (*send_xchar)(struct tty_struct *tty, char ch);
        int (*read_proc)(char *page, char **start, off_t off,
                          int count, int *eof, void *data);
        int (*write_proc)(struct file *file, const char *buffer,
                          unsigned long count, void *data);
        int (*tiocmget)(struct tty_struct *tty, struct file *file);
        int (*tiocmset)(struct tty_struct *tty, struct file *file,
                        unsigned int set, unsigned int clear);
};

struct tty_driver {
        int     magic;          /* magic number for this structure */
        struct cdev cdev;
        struct module   *owner;
        const char      *driver_name;
        const char      *devfs_name;
        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 proc_dir_entry *proc_entry; /* /proc fs entry */
        struct tty_driver *other; /* only used for the PTY driver */

        /*
         * Pointer to the tty data structures
         */

        struct tty_struct **ttys;
        struct termios **termios;
        struct termios **termios_locked;
        void *driver_state;     /* only used for the PTY driver */
       
        /*
         * Interface routines from the upper tty layer to the tty
         * driver.      Will be replaced with struct tty_operations.
         */

        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 (*break_ctl)(struct tty_struct *tty, int state);
        void (*flush_buffer)(struct tty_struct *tty);
        void (*set_ldisc)(struct tty_struct *tty);
        void (*wait_until_sent)(struct tty_struct *tty, int timeout);
        void (*send_xchar)(struct tty_struct *tty, char ch);
        int (*read_proc)(char *page, char **start, off_t off,
                          int count, int *eof, void *data);
        int (*write_proc)(struct file *file, const char *buffer,
                          unsigned long count, void *data);
        int (*tiocmget)(struct tty_struct *tty, struct file *file);
        int (*tiocmset)(struct tty_struct *tty, struct file *file,
                        unsigned int set, unsigned int clear);

        struct list_head tty_drivers;
};

extern struct list_head tty_drivers;

struct tty_driver *alloc_tty_driver(int lines);
void put_tty_driver(struct tty_driver *driver);
void tty_set_operations(struct tty_driver *driver, struct tty_operations *op);

/* 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.)
 *
 * TTY_DRIVER_NO_DEVFS --- if set, do not create devfs entries. This
 *      is only used by tty_register_driver().
 *
 */

#define TTY_DRIVER_INSTALLED            0x0001
#define TTY_DRIVER_RESET_TERMIOS        0x0002
#define TTY_DRIVER_REAL_RAW             0x0004
#define TTY_DRIVER_NO_DEVFS             0x0008

/* 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 */
#define TTY_DRIVER_TYPE_SYSCONS         0x0006

/* system subtypes (magic, used by tty_io.c) */
#define SYSTEM_TYPE_TTY                 0x0001
#define SYSTEM_TYPE_CONSOLE             0x0002
#define SYSTEM_TYPE_SYSCONS             0x0003
#define SYSTEM_TYPE_SYSPTMX             0x0004

/* pty subtypes (magic, used by tty_io.c) */
#define PTY_TYPE_MASTER                 0x0001
#define PTY_TYPE_SLAVE                  0x0002

/* serial subtype definitions */
#define SERIAL_TYPE_NORMAL      1
#define SERIAL_TYPE_CALLOUT     2

#endif /* #ifdef _LINUX_TTY_DRIVER_H */