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24d406a6bf
tty_operations->remove is normally called like:
queue_release_one_tty
->tty_shutdown
->tty_driver_remove_tty
->tty_operations->remove
However tty_shutdown() is called from queue_release_one_tty() only if
tty_operations->shutdown is NULL. But for pty, it is not.
pty_unix98_shutdown() is used there as ->shutdown.
So tty_operations->remove of pty (i.e. pty_unix98_remove()) is never
called. This results in invalid pty_count. I.e. what can be seen in
/proc/sys/kernel/pty/nr.
I see this was already reported at:
https://lkml.org/lkml/2009/11/5/370
But it was not fixed since then.
This patch is kind of a hackish way. The problem lies in ->install. We
allocate there another tty (so-called tty->link). So ->install is
called once, but ->remove twice, for both tty and tty->link. The fix
here is to count both tty and tty->link and divide the count by 2 for
user.
And to have ->remove called, let's make tty_driver_remove_tty() global
and call that from pty_unix98_shutdown() (tty_operations->shutdown).
While at it, let's document that when ->shutdown is defined,
tty_shutdown() is not called.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Alan Cox <alan@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
410 lines
14 KiB
C
410 lines
14 KiB
C
#ifndef _LINUX_TTY_DRIVER_H
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#define _LINUX_TTY_DRIVER_H
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/*
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* This structure defines the interface between the low-level tty
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* driver and the tty routines. The following routines can be
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* defined; unless noted otherwise, they are optional, and can be
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* filled in with a null pointer.
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*
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* struct tty_struct * (*lookup)(struct tty_driver *self, int idx)
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*
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* Return the tty device corresponding to idx, NULL if there is not
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* one currently in use and an ERR_PTR value on error. Called under
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* tty_mutex (for now!)
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*
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* Optional method. Default behaviour is to use the ttys array
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*
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* int (*install)(struct tty_driver *self, struct tty_struct *tty)
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*
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* Install a new tty into the tty driver internal tables. Used in
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* conjunction with lookup and remove methods.
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*
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* Optional method. Default behaviour is to use the ttys array
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*
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* void (*remove)(struct tty_driver *self, struct tty_struct *tty)
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*
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* Remove a closed tty from the tty driver internal tables. Used in
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* conjunction with lookup and remove methods.
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*
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* Optional method. Default behaviour is to use the ttys array
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*
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* int (*open)(struct tty_struct * tty, struct file * filp);
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*
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* This routine is called when a particular tty device is opened.
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* This routine is mandatory; if this routine is not filled in,
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* the attempted open will fail with ENODEV.
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*
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* Required method.
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*
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* void (*close)(struct tty_struct * tty, struct file * filp);
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*
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* This routine is called when a particular tty device is closed.
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*
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* Required method.
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*
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* void (*shutdown)(struct tty_struct * tty);
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*
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* This routine is called synchronously when a particular tty device
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* is closed for the last time freeing up the resources.
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* Note that tty_shutdown() is not called if ops->shutdown is defined.
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* This means one is responsible to take care of calling ops->remove (e.g.
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* via tty_driver_remove_tty) and releasing tty->termios.
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*
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*
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* void (*cleanup)(struct tty_struct * tty);
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*
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* This routine is called asynchronously when a particular tty device
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* is closed for the last time freeing up the resources. This is
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* actually the second part of shutdown for routines that might sleep.
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*
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*
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* int (*write)(struct tty_struct * tty,
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* const unsigned char *buf, int count);
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*
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* This routine is called by the kernel to write a series of
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* characters to the tty device. The characters may come from
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* user space or kernel space. This routine will return the
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* number of characters actually accepted for writing.
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*
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* Optional: Required for writable devices.
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*
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* int (*put_char)(struct tty_struct *tty, unsigned char ch);
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*
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* This routine is called by the kernel to write a single
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* character to the tty device. If the kernel uses this routine,
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* it must call the flush_chars() routine (if defined) when it is
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* done stuffing characters into the driver. If there is no room
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* in the queue, the character is ignored.
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*
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* Optional: Kernel will use the write method if not provided.
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*
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* Note: Do not call this function directly, call tty_put_char
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*
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* void (*flush_chars)(struct tty_struct *tty);
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*
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* This routine is called by the kernel after it has written a
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* series of characters to the tty device using put_char().
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*
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* Optional:
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*
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* Note: Do not call this function directly, call tty_driver_flush_chars
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*
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* int (*write_room)(struct tty_struct *tty);
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*
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* This routine returns the numbers of characters the tty driver
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* will accept for queuing to be written. This number is subject
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* to change as output buffers get emptied, or if the output flow
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* control is acted.
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*
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* Required if write method is provided else not needed.
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*
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* Note: Do not call this function directly, call tty_write_room
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*
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* int (*ioctl)(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
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*
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* This routine allows the tty driver to implement
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* device-specific ioctls. If the ioctl number passed in cmd
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* is not recognized by the driver, it should return ENOIOCTLCMD.
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*
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* Optional
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*
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* long (*compat_ioctl)(struct tty_struct *tty,,
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* unsigned int cmd, unsigned long arg);
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*
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* implement ioctl processing for 32 bit process on 64 bit system
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*
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* Optional
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*
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* void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
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*
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* This routine allows the tty driver to be notified when
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* device's termios settings have changed.
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*
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* Optional: Called under the termios lock
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*
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*
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* void (*set_ldisc)(struct tty_struct *tty);
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*
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* This routine allows the tty driver to be notified when the
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* device's termios settings have changed.
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*
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* Optional: Called under BKL (currently)
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*
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* void (*throttle)(struct tty_struct * tty);
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*
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* This routine notifies the tty driver that input buffers for
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* the line discipline are close to full, and it should somehow
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* signal that no more characters should be sent to the tty.
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*
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* Optional: Always invoke via tty_throttle(), called under the
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* termios lock.
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*
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* void (*unthrottle)(struct tty_struct * tty);
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*
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* This routine notifies the tty drivers that it should signals
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* that characters can now be sent to the tty without fear of
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* overrunning the input buffers of the line disciplines.
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*
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* Optional: Always invoke via tty_unthrottle(), called under the
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* termios lock.
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*
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* void (*stop)(struct tty_struct *tty);
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*
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* This routine notifies the tty driver that it should stop
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* outputting characters to the tty device.
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*
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* Optional:
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*
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* Note: Call stop_tty not this method.
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*
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* void (*start)(struct tty_struct *tty);
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*
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* This routine notifies the tty driver that it resume sending
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* characters to the tty device.
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*
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* Optional:
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*
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* Note: Call start_tty not this method.
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*
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* void (*hangup)(struct tty_struct *tty);
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*
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* This routine notifies the tty driver that it should hang up the
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* tty device.
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*
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* Optional:
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*
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* int (*break_ctl)(struct tty_struct *tty, int state);
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*
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* This optional routine requests the tty driver to turn on or
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* off BREAK status on the RS-232 port. If state is -1,
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* then the BREAK status should be turned on; if state is 0, then
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* BREAK should be turned off.
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*
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* If this routine is implemented, the high-level tty driver will
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* handle the following ioctls: TCSBRK, TCSBRKP, TIOCSBRK,
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* TIOCCBRK.
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*
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* If the driver sets TTY_DRIVER_HARDWARE_BREAK then the interface
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* will also be called with actual times and the hardware is expected
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* to do the delay work itself. 0 and -1 are still used for on/off.
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*
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* Optional: Required for TCSBRK/BRKP/etc handling.
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*
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* void (*wait_until_sent)(struct tty_struct *tty, int timeout);
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*
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* This routine waits until the device has written out all of the
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* characters in its transmitter FIFO.
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*
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* Optional: If not provided the device is assumed to have no FIFO
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*
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* Note: Usually correct to call tty_wait_until_sent
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*
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* void (*send_xchar)(struct tty_struct *tty, char ch);
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*
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* This routine is used to send a high-priority XON/XOFF
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* character to the device.
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*
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* Optional: If not provided then the write method is called under
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* the atomic write lock to keep it serialized with the ldisc.
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*
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* int (*resize)(struct tty_struct *tty, struct winsize *ws)
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*
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* Called when a termios request is issued which changes the
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* requested terminal geometry.
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*
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* Optional: the default action is to update the termios structure
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* without error. This is usually the correct behaviour. Drivers should
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* not force errors here if they are not resizable objects (eg a serial
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* line). See tty_do_resize() if you need to wrap the standard method
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* in your own logic - the usual case.
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*
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* void (*set_termiox)(struct tty_struct *tty, struct termiox *new);
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*
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* Called when the device receives a termiox based ioctl. Passes down
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* the requested data from user space. This method will not be invoked
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* unless the tty also has a valid tty->termiox pointer.
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*
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* Optional: Called under the termios lock
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*
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* int (*get_icount)(struct tty_struct *tty, struct serial_icounter *icount);
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*
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* Called when the device receives a TIOCGICOUNT ioctl. Passed a kernel
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* structure to complete. This method is optional and will only be called
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* if provided (otherwise EINVAL will be returned).
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*/
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#include <linux/fs.h>
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#include <linux/list.h>
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#include <linux/cdev.h>
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#include <linux/termios.h>
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struct tty_struct;
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struct tty_driver;
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struct serial_icounter_struct;
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struct tty_operations {
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struct tty_struct * (*lookup)(struct tty_driver *driver,
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struct inode *inode, int idx);
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int (*install)(struct tty_driver *driver, struct tty_struct *tty);
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void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
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int (*open)(struct tty_struct * tty, struct file * filp);
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void (*close)(struct tty_struct * tty, struct file * filp);
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void (*shutdown)(struct tty_struct *tty);
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void (*cleanup)(struct tty_struct *tty);
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int (*write)(struct tty_struct * tty,
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const unsigned char *buf, int count);
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int (*put_char)(struct tty_struct *tty, unsigned char ch);
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void (*flush_chars)(struct tty_struct *tty);
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int (*write_room)(struct tty_struct *tty);
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int (*chars_in_buffer)(struct tty_struct *tty);
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int (*ioctl)(struct tty_struct *tty,
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unsigned int cmd, unsigned long arg);
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long (*compat_ioctl)(struct tty_struct *tty,
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unsigned int cmd, unsigned long arg);
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void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
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void (*throttle)(struct tty_struct * tty);
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void (*unthrottle)(struct tty_struct * tty);
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void (*stop)(struct tty_struct *tty);
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void (*start)(struct tty_struct *tty);
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void (*hangup)(struct tty_struct *tty);
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int (*break_ctl)(struct tty_struct *tty, int state);
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void (*flush_buffer)(struct tty_struct *tty);
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void (*set_ldisc)(struct tty_struct *tty);
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void (*wait_until_sent)(struct tty_struct *tty, int timeout);
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void (*send_xchar)(struct tty_struct *tty, char ch);
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int (*tiocmget)(struct tty_struct *tty);
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int (*tiocmset)(struct tty_struct *tty,
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unsigned int set, unsigned int clear);
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int (*resize)(struct tty_struct *tty, struct winsize *ws);
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int (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);
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int (*get_icount)(struct tty_struct *tty,
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struct serial_icounter_struct *icount);
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#ifdef CONFIG_CONSOLE_POLL
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int (*poll_init)(struct tty_driver *driver, int line, char *options);
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int (*poll_get_char)(struct tty_driver *driver, int line);
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void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
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#endif
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const struct file_operations *proc_fops;
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};
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struct tty_driver {
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int magic; /* magic number for this structure */
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struct kref kref; /* Reference management */
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struct cdev cdev;
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struct module *owner;
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const char *driver_name;
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const char *name;
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int name_base; /* offset of printed name */
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int major; /* major device number */
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int minor_start; /* start of minor device number */
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int minor_num; /* number of *possible* devices */
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int num; /* number of devices allocated */
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short type; /* type of tty driver */
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short subtype; /* subtype of tty driver */
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struct ktermios init_termios; /* Initial termios */
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int flags; /* tty driver flags */
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struct proc_dir_entry *proc_entry; /* /proc fs entry */
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struct tty_driver *other; /* only used for the PTY driver */
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/*
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* Pointer to the tty data structures
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*/
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struct tty_struct **ttys;
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struct ktermios **termios;
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struct ktermios **termios_locked;
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void *driver_state;
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/*
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* Driver methods
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*/
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const struct tty_operations *ops;
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struct list_head tty_drivers;
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};
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extern struct list_head tty_drivers;
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extern struct tty_driver *alloc_tty_driver(int lines);
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extern void put_tty_driver(struct tty_driver *driver);
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extern void tty_set_operations(struct tty_driver *driver,
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const struct tty_operations *op);
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extern struct tty_driver *tty_find_polling_driver(char *name, int *line);
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extern void tty_driver_kref_put(struct tty_driver *driver);
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static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
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{
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kref_get(&d->kref);
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return d;
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}
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/* tty driver magic number */
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#define TTY_DRIVER_MAGIC 0x5402
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/*
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* tty driver flags
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*
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* TTY_DRIVER_RESET_TERMIOS --- requests the tty layer to reset the
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* termios setting when the last process has closed the device.
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* Used for PTY's, in particular.
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*
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* TTY_DRIVER_REAL_RAW --- if set, indicates that the driver will
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* guarantee never not to set any special character handling
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* flags if ((IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR ||
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* !INPCK)). That is, if there is no reason for the driver to
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* send notifications of parity and break characters up to the
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* line driver, it won't do so. This allows the line driver to
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* optimize for this case if this flag is set. (Note that there
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* is also a promise, if the above case is true, not to signal
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* overruns, either.)
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*
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* TTY_DRIVER_DYNAMIC_DEV --- if set, the individual tty devices need
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* to be registered with a call to tty_register_device() when the
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* device is found in the system and unregistered with a call to
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* tty_unregister_device() so the devices will be show up
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* properly in sysfs. If not set, driver->num entries will be
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* created by the tty core in sysfs when tty_register_driver() is
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* called. This is to be used by drivers that have tty devices
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* that can appear and disappear while the main tty driver is
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* registered with the tty core.
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*
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* TTY_DRIVER_DEVPTS_MEM -- don't use the standard arrays, instead
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* use dynamic memory keyed through the devpts filesystem. This
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* is only applicable to the pty driver.
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*
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* TTY_DRIVER_HARDWARE_BREAK -- hardware handles break signals. Pass
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* the requested timeout to the caller instead of using a simple
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* on/off interface.
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*
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*/
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#define TTY_DRIVER_INSTALLED 0x0001
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#define TTY_DRIVER_RESET_TERMIOS 0x0002
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#define TTY_DRIVER_REAL_RAW 0x0004
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#define TTY_DRIVER_DYNAMIC_DEV 0x0008
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#define TTY_DRIVER_DEVPTS_MEM 0x0010
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#define TTY_DRIVER_HARDWARE_BREAK 0x0020
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/* tty driver types */
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#define TTY_DRIVER_TYPE_SYSTEM 0x0001
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#define TTY_DRIVER_TYPE_CONSOLE 0x0002
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#define TTY_DRIVER_TYPE_SERIAL 0x0003
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#define TTY_DRIVER_TYPE_PTY 0x0004
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#define TTY_DRIVER_TYPE_SCC 0x0005 /* scc driver */
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#define TTY_DRIVER_TYPE_SYSCONS 0x0006
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/* system subtypes (magic, used by tty_io.c) */
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#define SYSTEM_TYPE_TTY 0x0001
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#define SYSTEM_TYPE_CONSOLE 0x0002
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#define SYSTEM_TYPE_SYSCONS 0x0003
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#define SYSTEM_TYPE_SYSPTMX 0x0004
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/* pty subtypes (magic, used by tty_io.c) */
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#define PTY_TYPE_MASTER 0x0001
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#define PTY_TYPE_SLAVE 0x0002
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/* serial subtype definitions */
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#define SERIAL_TYPE_NORMAL 1
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#endif /* #ifdef _LINUX_TTY_DRIVER_H */
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