LCOV - code coverage report
Current view: top level - include/linux - tty_driver.h (source / functions) Hit Total Coverage
Test: coverage.info Lines: 1 2 50.0 %
Date: 2023-07-19 18:55:55 Functions: 0 0 -

          Line data    Source code
       1             : /* SPDX-License-Identifier: GPL-2.0 */
       2             : #ifndef _LINUX_TTY_DRIVER_H
       3             : #define _LINUX_TTY_DRIVER_H
       4             : 
       5             : #include <linux/export.h>
       6             : #include <linux/fs.h>
       7             : #include <linux/kref.h>
       8             : #include <linux/list.h>
       9             : #include <linux/cdev.h>
      10             : #include <linux/uaccess.h>
      11             : #include <linux/termios.h>
      12             : #include <linux/seq_file.h>
      13             : 
      14             : struct tty_struct;
      15             : struct tty_driver;
      16             : struct serial_icounter_struct;
      17             : struct serial_struct;
      18             : 
      19             : /**
      20             :  * struct tty_operations -- interface between driver and tty
      21             :  *
      22             :  * @lookup: ``struct tty_struct *()(struct tty_driver *self, struct file *,
      23             :  *                                  int idx)``
      24             :  *
      25             :  *      Return the tty device corresponding to @idx, %NULL if there is not
      26             :  *      one currently in use and an %ERR_PTR value on error. Called under
      27             :  *      %tty_mutex (for now!)
      28             :  *
      29             :  *      Optional method. Default behaviour is to use the @self->ttys array.
      30             :  *
      31             :  * @install: ``int ()(struct tty_driver *self, struct tty_struct *tty)``
      32             :  *
      33             :  *      Install a new @tty into the @self's internal tables. Used in
      34             :  *      conjunction with @lookup and @remove methods.
      35             :  *
      36             :  *      Optional method. Default behaviour is to use the @self->ttys array.
      37             :  *
      38             :  * @remove: ``void ()(struct tty_driver *self, struct tty_struct *tty)``
      39             :  *
      40             :  *      Remove a closed @tty from the @self's internal tables. Used in
      41             :  *      conjunction with @lookup and @remove methods.
      42             :  *
      43             :  *      Optional method. Default behaviour is to use the @self->ttys array.
      44             :  *
      45             :  * @open: ``int ()(struct tty_struct *tty, struct file *)``
      46             :  *
      47             :  *      This routine is called when a particular @tty device is opened. This
      48             :  *      routine is mandatory; if this routine is not filled in, the attempted
      49             :  *      open will fail with %ENODEV.
      50             :  *
      51             :  *      Required method. Called with tty lock held. May sleep.
      52             :  *
      53             :  * @close: ``void ()(struct tty_struct *tty, struct file *)``
      54             :  *
      55             :  *      This routine is called when a particular @tty device is closed. At the
      56             :  *      point of return from this call the driver must make no further ldisc
      57             :  *      calls of any kind.
      58             :  *
      59             :  *      Remark: called even if the corresponding @open() failed.
      60             :  *
      61             :  *      Required method. Called with tty lock held. May sleep.
      62             :  *
      63             :  * @shutdown: ``void ()(struct tty_struct *tty)``
      64             :  *
      65             :  *      This routine is called under the tty lock when a particular @tty device
      66             :  *      is closed for the last time. It executes before the @tty resources
      67             :  *      are freed so may execute while another function holds a @tty kref.
      68             :  *
      69             :  * @cleanup: ``void ()(struct tty_struct *tty)``
      70             :  *
      71             :  *      This routine is called asynchronously when a particular @tty device
      72             :  *      is closed for the last time freeing up the resources. This is
      73             :  *      actually the second part of shutdown for routines that might sleep.
      74             :  *
      75             :  * @write: ``int ()(struct tty_struct *tty, const unsigned char *buf,
      76             :  *                  int count)``
      77             :  *
      78             :  *      This routine is called by the kernel to write a series (@count) of
      79             :  *      characters (@buf) to the @tty device. The characters may come from
      80             :  *      user space or kernel space.  This routine will return the
      81             :  *      number of characters actually accepted for writing.
      82             :  *
      83             :  *      May occur in parallel in special cases. Because this includes panic
      84             :  *      paths drivers generally shouldn't try and do clever locking here.
      85             :  *
      86             :  *      Optional: Required for writable devices. May not sleep.
      87             :  *
      88             :  * @put_char: ``int ()(struct tty_struct *tty, unsigned char ch)``
      89             :  *
      90             :  *      This routine is called by the kernel to write a single character @ch to
      91             :  *      the @tty device. If the kernel uses this routine, it must call the
      92             :  *      @flush_chars() routine (if defined) when it is done stuffing characters
      93             :  *      into the driver. If there is no room in the queue, the character is
      94             :  *      ignored.
      95             :  *
      96             :  *      Optional: Kernel will use the @write method if not provided. Do not
      97             :  *      call this function directly, call tty_put_char().
      98             :  *
      99             :  * @flush_chars: ``void ()(struct tty_struct *tty)``
     100             :  *
     101             :  *      This routine is called by the kernel after it has written a
     102             :  *      series of characters to the tty device using @put_char().
     103             :  *
     104             :  *      Optional. Do not call this function directly, call
     105             :  *      tty_driver_flush_chars().
     106             :  *
     107             :  * @write_room: ``unsigned int ()(struct tty_struct *tty)``
     108             :  *
     109             :  *      This routine returns the numbers of characters the @tty driver
     110             :  *      will accept for queuing to be written.  This number is subject
     111             :  *      to change as output buffers get emptied, or if the output flow
     112             :  *      control is acted.
     113             :  *
     114             :  *      The ldisc is responsible for being intelligent about multi-threading of
     115             :  *      write_room/write calls
     116             :  *
     117             :  *      Required if @write method is provided else not needed. Do not call this
     118             :  *      function directly, call tty_write_room()
     119             :  *
     120             :  * @chars_in_buffer: ``unsigned int ()(struct tty_struct *tty)``
     121             :  *
     122             :  *      This routine returns the number of characters in the device private
     123             :  *      output queue. Used in tty_wait_until_sent() and for poll()
     124             :  *      implementation.
     125             :  *
     126             :  *      Optional: if not provided, it is assumed there is no queue on the
     127             :  *      device. Do not call this function directly, call tty_chars_in_buffer().
     128             :  *
     129             :  * @ioctl: ``int ()(struct tty_struct *tty, unsigned int cmd,
     130             :  *                  unsigned long arg)``
     131             :  *
     132             :  *      This routine allows the @tty driver to implement device-specific
     133             :  *      ioctls. If the ioctl number passed in @cmd is not recognized by the
     134             :  *      driver, it should return %ENOIOCTLCMD.
     135             :  *
     136             :  *      Optional.
     137             :  *
     138             :  * @compat_ioctl: ``long ()(struct tty_struct *tty, unsigned int cmd,
     139             :  *                        unsigned long arg)``
     140             :  *
     141             :  *      Implement ioctl processing for 32 bit process on 64 bit system.
     142             :  *
     143             :  *      Optional.
     144             :  *
     145             :  * @set_termios: ``void ()(struct tty_struct *tty, const struct ktermios *old)``
     146             :  *
     147             :  *      This routine allows the @tty driver to be notified when device's
     148             :  *      termios settings have changed. New settings are in @tty->termios.
     149             :  *      Previous settings are passed in the @old argument.
     150             :  *
     151             :  *      The API is defined such that the driver should return the actual modes
     152             :  *      selected. This means that the driver is responsible for modifying any
     153             :  *      bits in @tty->termios it cannot fulfill to indicate the actual modes
     154             :  *      being used.
     155             :  *
     156             :  *      Optional. Called under the @tty->termios_rwsem. May sleep.
     157             :  *
     158             :  * @set_ldisc: ``void ()(struct tty_struct *tty)``
     159             :  *
     160             :  *      This routine allows the @tty driver to be notified when the device's
     161             :  *      line discipline is being changed. At the point this is done the
     162             :  *      discipline is not yet usable.
     163             :  *
     164             :  *      Optional. Called under the @tty->ldisc_sem and @tty->termios_rwsem.
     165             :  *
     166             :  * @throttle: ``void ()(struct tty_struct *tty)``
     167             :  *
     168             :  *      This routine notifies the @tty driver that input buffers for the line
     169             :  *      discipline are close to full, and it should somehow signal that no more
     170             :  *      characters should be sent to the @tty.
     171             :  *
     172             :  *      Serialization including with @unthrottle() is the job of the ldisc
     173             :  *      layer.
     174             :  *
     175             :  *      Optional: Always invoke via tty_throttle_safe(). Called under the
     176             :  *      @tty->termios_rwsem.
     177             :  *
     178             :  * @unthrottle: ``void ()(struct tty_struct *tty)``
     179             :  *
     180             :  *      This routine notifies the @tty driver that it should signal that
     181             :  *      characters can now be sent to the @tty without fear of overrunning the
     182             :  *      input buffers of the line disciplines.
     183             :  *
     184             :  *      Optional. Always invoke via tty_unthrottle(). Called under the
     185             :  *      @tty->termios_rwsem.
     186             :  *
     187             :  * @stop: ``void ()(struct tty_struct *tty)``
     188             :  *
     189             :  *      This routine notifies the @tty driver that it should stop outputting
     190             :  *      characters to the tty device.
     191             :  *
     192             :  *      Called with @tty->flow.lock held. Serialized with @start() method.
     193             :  *
     194             :  *      Optional. Always invoke via stop_tty().
     195             :  *
     196             :  * @start: ``void ()(struct tty_struct *tty)``
     197             :  *
     198             :  *      This routine notifies the @tty driver that it resumed sending
     199             :  *      characters to the @tty device.
     200             :  *
     201             :  *      Called with @tty->flow.lock held. Serialized with stop() method.
     202             :  *
     203             :  *      Optional. Always invoke via start_tty().
     204             :  *
     205             :  * @hangup: ``void ()(struct tty_struct *tty)``
     206             :  *
     207             :  *      This routine notifies the @tty driver that it should hang up the @tty
     208             :  *      device.
     209             :  *
     210             :  *      Optional. Called with tty lock held.
     211             :  *
     212             :  * @break_ctl: ``int ()(struct tty_struct *tty, int state)``
     213             :  *
     214             :  *      This optional routine requests the @tty driver to turn on or off BREAK
     215             :  *      status on the RS-232 port. If @state is -1, then the BREAK status
     216             :  *      should be turned on; if @state is 0, then BREAK should be turned off.
     217             :  *
     218             :  *      If this routine is implemented, the high-level tty driver will handle
     219             :  *      the following ioctls: %TCSBRK, %TCSBRKP, %TIOCSBRK, %TIOCCBRK.
     220             :  *
     221             :  *      If the driver sets %TTY_DRIVER_HARDWARE_BREAK in tty_alloc_driver(),
     222             :  *      then the interface will also be called with actual times and the
     223             :  *      hardware is expected to do the delay work itself. 0 and -1 are still
     224             :  *      used for on/off.
     225             :  *
     226             :  *      Optional: Required for %TCSBRK/%BRKP/etc. handling. May sleep.
     227             :  *
     228             :  * @flush_buffer: ``void ()(struct tty_struct *tty)``
     229             :  *
     230             :  *      This routine discards device private output buffer. Invoked on close,
     231             :  *      hangup, to implement %TCOFLUSH ioctl and similar.
     232             :  *
     233             :  *      Optional: if not provided, it is assumed there is no queue on the
     234             :  *      device. Do not call this function directly, call
     235             :  *      tty_driver_flush_buffer().
     236             :  *
     237             :  * @wait_until_sent: ``void ()(struct tty_struct *tty, int timeout)``
     238             :  *
     239             :  *      This routine waits until the device has written out all of the
     240             :  *      characters in its transmitter FIFO. Or until @timeout (in jiffies) is
     241             :  *      reached.
     242             :  *
     243             :  *      Optional: If not provided, the device is assumed to have no FIFO.
     244             :  *      Usually correct to invoke via tty_wait_until_sent(). May sleep.
     245             :  *
     246             :  * @send_xchar: ``void ()(struct tty_struct *tty, char ch)``
     247             :  *
     248             :  *      This routine is used to send a high-priority XON/XOFF character (@ch)
     249             :  *      to the @tty device.
     250             :  *
     251             :  *      Optional: If not provided, then the @write method is called under
     252             :  *      the @tty->atomic_write_lock to keep it serialized with the ldisc.
     253             :  *
     254             :  * @tiocmget: ``int ()(struct tty_struct *tty)``
     255             :  *
     256             :  *      This routine is used to obtain the modem status bits from the @tty
     257             :  *      driver.
     258             :  *
     259             :  *      Optional: If not provided, then %ENOTTY is returned from the %TIOCMGET
     260             :  *      ioctl. Do not call this function directly, call tty_tiocmget().
     261             :  *
     262             :  * @tiocmset: ``int ()(struct tty_struct *tty,
     263             :  *                     unsigned int set, unsigned int clear)``
     264             :  *
     265             :  *      This routine is used to set the modem status bits to the @tty driver.
     266             :  *      First, @clear bits should be cleared, then @set bits set.
     267             :  *
     268             :  *      Optional: If not provided, then %ENOTTY is returned from the %TIOCMSET
     269             :  *      ioctl. Do not call this function directly, call tty_tiocmset().
     270             :  *
     271             :  * @resize: ``int ()(struct tty_struct *tty, struct winsize *ws)``
     272             :  *
     273             :  *      Called when a termios request is issued which changes the requested
     274             :  *      terminal geometry to @ws.
     275             :  *
     276             :  *      Optional: the default action is to update the termios structure
     277             :  *      without error. This is usually the correct behaviour. Drivers should
     278             :  *      not force errors here if they are not resizable objects (e.g. a serial
     279             :  *      line). See tty_do_resize() if you need to wrap the standard method
     280             :  *      in your own logic -- the usual case.
     281             :  *
     282             :  * @get_icount: ``int ()(struct tty_struct *tty,
     283             :  *                       struct serial_icounter *icount)``
     284             :  *
     285             :  *      Called when the @tty device receives a %TIOCGICOUNT ioctl. Passed a
     286             :  *      kernel structure @icount to complete.
     287             :  *
     288             :  *      Optional: called only if provided, otherwise %ENOTTY will be returned.
     289             :  *
     290             :  * @get_serial: ``int ()(struct tty_struct *tty, struct serial_struct *p)``
     291             :  *
     292             :  *      Called when the @tty device receives a %TIOCGSERIAL ioctl. Passed a
     293             :  *      kernel structure @p (&struct serial_struct) to complete.
     294             :  *
     295             :  *      Optional: called only if provided, otherwise %ENOTTY will be returned.
     296             :  *      Do not call this function directly, call tty_tiocgserial().
     297             :  *
     298             :  * @set_serial: ``int ()(struct tty_struct *tty, struct serial_struct *p)``
     299             :  *
     300             :  *      Called when the @tty device receives a %TIOCSSERIAL ioctl. Passed a
     301             :  *      kernel structure @p (&struct serial_struct) to set the values from.
     302             :  *
     303             :  *      Optional: called only if provided, otherwise %ENOTTY will be returned.
     304             :  *      Do not call this function directly, call tty_tiocsserial().
     305             :  *
     306             :  * @show_fdinfo: ``void ()(struct tty_struct *tty, struct seq_file *m)``
     307             :  *
     308             :  *      Called when the @tty device file descriptor receives a fdinfo request
     309             :  *      from VFS (to show in /proc/<pid>/fdinfo/). @m should be filled with
     310             :  *      information.
     311             :  *
     312             :  *      Optional: called only if provided, otherwise nothing is written to @m.
     313             :  *      Do not call this function directly, call tty_show_fdinfo().
     314             :  *
     315             :  * @poll_init: ``int ()(struct tty_driver *driver, int line, char *options)``
     316             :  *
     317             :  *      kgdboc support (Documentation/dev-tools/kgdb.rst). This routine is
     318             :  *      called to initialize the HW for later use by calling @poll_get_char or
     319             :  *      @poll_put_char.
     320             :  *
     321             :  *      Optional: called only if provided, otherwise skipped as a non-polling
     322             :  *      driver.
     323             :  *
     324             :  * @poll_get_char: ``int ()(struct tty_driver *driver, int line)``
     325             :  *
     326             :  *      kgdboc support (see @poll_init). @driver should read a character from a
     327             :  *      tty identified by @line and return it.
     328             :  *
     329             :  *      Optional: called only if @poll_init provided.
     330             :  *
     331             :  * @poll_put_char: ``void ()(struct tty_driver *driver, int line, char ch)``
     332             :  *
     333             :  *      kgdboc support (see @poll_init). @driver should write character @ch to
     334             :  *      a tty identified by @line.
     335             :  *
     336             :  *      Optional: called only if @poll_init provided.
     337             :  *
     338             :  * @proc_show: ``int ()(struct seq_file *m, void *driver)``
     339             :  *
     340             :  *      Driver @driver (cast to &struct tty_driver) can show additional info in
     341             :  *      /proc/tty/driver/<driver_name>. It is enough to fill in the information
     342             :  *      into @m.
     343             :  *
     344             :  *      Optional: called only if provided, otherwise no /proc entry created.
     345             :  *
     346             :  * This structure defines the interface between the low-level tty driver and
     347             :  * the tty routines. These routines can be defined. Unless noted otherwise,
     348             :  * they are optional, and can be filled in with a %NULL pointer.
     349             :  */
     350             : struct tty_operations {
     351             :         struct tty_struct * (*lookup)(struct tty_driver *driver,
     352             :                         struct file *filp, int idx);
     353             :         int  (*install)(struct tty_driver *driver, struct tty_struct *tty);
     354             :         void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
     355             :         int  (*open)(struct tty_struct * tty, struct file * filp);
     356             :         void (*close)(struct tty_struct * tty, struct file * filp);
     357             :         void (*shutdown)(struct tty_struct *tty);
     358             :         void (*cleanup)(struct tty_struct *tty);
     359             :         int  (*write)(struct tty_struct * tty,
     360             :                       const unsigned char *buf, int count);
     361             :         int  (*put_char)(struct tty_struct *tty, unsigned char ch);
     362             :         void (*flush_chars)(struct tty_struct *tty);
     363             :         unsigned int (*write_room)(struct tty_struct *tty);
     364             :         unsigned int (*chars_in_buffer)(struct tty_struct *tty);
     365             :         int  (*ioctl)(struct tty_struct *tty,
     366             :                     unsigned int cmd, unsigned long arg);
     367             :         long (*compat_ioctl)(struct tty_struct *tty,
     368             :                              unsigned int cmd, unsigned long arg);
     369             :         void (*set_termios)(struct tty_struct *tty, const struct ktermios *old);
     370             :         void (*throttle)(struct tty_struct * tty);
     371             :         void (*unthrottle)(struct tty_struct * tty);
     372             :         void (*stop)(struct tty_struct *tty);
     373             :         void (*start)(struct tty_struct *tty);
     374             :         void (*hangup)(struct tty_struct *tty);
     375             :         int (*break_ctl)(struct tty_struct *tty, int state);
     376             :         void (*flush_buffer)(struct tty_struct *tty);
     377             :         void (*set_ldisc)(struct tty_struct *tty);
     378             :         void (*wait_until_sent)(struct tty_struct *tty, int timeout);
     379             :         void (*send_xchar)(struct tty_struct *tty, char ch);
     380             :         int (*tiocmget)(struct tty_struct *tty);
     381             :         int (*tiocmset)(struct tty_struct *tty,
     382             :                         unsigned int set, unsigned int clear);
     383             :         int (*resize)(struct tty_struct *tty, struct winsize *ws);
     384             :         int (*get_icount)(struct tty_struct *tty,
     385             :                                 struct serial_icounter_struct *icount);
     386             :         int  (*get_serial)(struct tty_struct *tty, struct serial_struct *p);
     387             :         int  (*set_serial)(struct tty_struct *tty, struct serial_struct *p);
     388             :         void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m);
     389             : #ifdef CONFIG_CONSOLE_POLL
     390             :         int (*poll_init)(struct tty_driver *driver, int line, char *options);
     391             :         int (*poll_get_char)(struct tty_driver *driver, int line);
     392             :         void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
     393             : #endif
     394             :         int (*proc_show)(struct seq_file *m, void *driver);
     395             : } __randomize_layout;
     396             : 
     397             : /**
     398             :  * struct tty_driver -- driver for TTY devices
     399             :  *
     400             :  * @kref: reference counting. Reaching zero frees all the internals and the
     401             :  *        driver.
     402             :  * @cdevs: allocated/registered character /dev devices
     403             :  * @owner: modules owning this driver. Used drivers cannot be rmmod'ed.
     404             :  *         Automatically set by tty_alloc_driver().
     405             :  * @driver_name: name of the driver used in /proc/tty
     406             :  * @name: used for constructing /dev node name
     407             :  * @name_base: used as a number base for constructing /dev node name
     408             :  * @major: major /dev device number (zero for autoassignment)
     409             :  * @minor_start: the first minor /dev device number
     410             :  * @num: number of devices allocated
     411             :  * @type: type of tty driver (%TTY_DRIVER_TYPE_)
     412             :  * @subtype: subtype of tty driver (%SYSTEM_TYPE_, %PTY_TYPE_, %SERIAL_TYPE_)
     413             :  * @init_termios: termios to set to each tty initially (e.g. %tty_std_termios)
     414             :  * @flags: tty driver flags (%TTY_DRIVER_)
     415             :  * @proc_entry: proc fs entry, used internally
     416             :  * @other: driver of the linked tty; only used for the PTY driver
     417             :  * @ttys: array of active &struct tty_struct, set by tty_standard_install()
     418             :  * @ports: array of &struct tty_port; can be set during initialization by
     419             :  *         tty_port_link_device() and similar
     420             :  * @termios: storage for termios at each TTY close for the next open
     421             :  * @driver_state: pointer to driver's arbitrary data
     422             :  * @ops: driver hooks for TTYs. Set them using tty_set_operations(). Use &struct
     423             :  *       tty_port helpers in them as much as possible.
     424             :  * @tty_drivers: used internally to link tty_drivers together
     425             :  *
     426             :  * The usual handling of &struct tty_driver is to allocate it by
     427             :  * tty_alloc_driver(), set up all the necessary members, and register it by
     428             :  * tty_register_driver(). At last, the driver is torn down by calling
     429             :  * tty_unregister_driver() followed by tty_driver_kref_put().
     430             :  *
     431             :  * The fields required to be set before calling tty_register_driver() include
     432             :  * @driver_name, @name, @type, @subtype, @init_termios, and @ops.
     433             :  */
     434             : struct tty_driver {
     435             :         struct kref kref;
     436             :         struct cdev **cdevs;
     437             :         struct module   *owner;
     438             :         const char      *driver_name;
     439             :         const char      *name;
     440             :         int     name_base;
     441             :         int     major;
     442             :         int     minor_start;
     443             :         unsigned int    num;
     444             :         short   type;
     445             :         short   subtype;
     446             :         struct ktermios init_termios;
     447             :         unsigned long   flags;
     448             :         struct proc_dir_entry *proc_entry;
     449             :         struct tty_driver *other;
     450             : 
     451             :         /*
     452             :          * Pointer to the tty data structures
     453             :          */
     454             :         struct tty_struct **ttys;
     455             :         struct tty_port **ports;
     456             :         struct ktermios **termios;
     457             :         void *driver_state;
     458             : 
     459             :         /*
     460             :          * Driver methods
     461             :          */
     462             : 
     463             :         const struct tty_operations *ops;
     464             :         struct list_head tty_drivers;
     465             : } __randomize_layout;
     466             : 
     467             : extern struct list_head tty_drivers;
     468             : 
     469             : struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
     470             :                 unsigned long flags);
     471             : struct tty_driver *tty_find_polling_driver(char *name, int *line);
     472             : 
     473             : void tty_driver_kref_put(struct tty_driver *driver);
     474             : 
     475             : /* Use TTY_DRIVER_* flags below */
     476             : #define tty_alloc_driver(lines, flags) \
     477             :                 __tty_alloc_driver(lines, THIS_MODULE, flags)
     478             : 
     479             : static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
     480             : {
     481           0 :         kref_get(&d->kref);
     482             :         return d;
     483             : }
     484             : 
     485             : static inline void tty_set_operations(struct tty_driver *driver,
     486             :                 const struct tty_operations *op)
     487             : {
     488           5 :         driver->ops = op;
     489             : }
     490             : 
     491             : /**
     492             :  * DOC: TTY Driver Flags
     493             :  *
     494             :  * TTY_DRIVER_RESET_TERMIOS
     495             :  *      Requests the tty layer to reset the termios setting when the last
     496             :  *      process has closed the device. Used for PTYs, in particular.
     497             :  *
     498             :  * TTY_DRIVER_REAL_RAW
     499             :  *      Indicates that the driver will guarantee not to set any special
     500             :  *      character handling flags if this is set for the tty:
     501             :  *
     502             :  *      ``(IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR || !INPCK)``
     503             :  *
     504             :  *      That is, if there is no reason for the driver to
     505             :  *      send notifications of parity and break characters up to the line
     506             :  *      driver, it won't do so.  This allows the line driver to optimize for
     507             :  *      this case if this flag is set.  (Note that there is also a promise, if
     508             :  *      the above case is true, not to signal overruns, either.)
     509             :  *
     510             :  * TTY_DRIVER_DYNAMIC_DEV
     511             :  *      The individual tty devices need to be registered with a call to
     512             :  *      tty_register_device() when the device is found in the system and
     513             :  *      unregistered with a call to tty_unregister_device() so the devices will
     514             :  *      be show up properly in sysfs.  If not set, all &tty_driver.num entries
     515             :  *      will be created by the tty core in sysfs when tty_register_driver() is
     516             :  *      called.  This is to be used by drivers that have tty devices that can
     517             :  *      appear and disappear while the main tty driver is registered with the
     518             :  *      tty core.
     519             :  *
     520             :  * TTY_DRIVER_DEVPTS_MEM
     521             :  *      Don't use the standard arrays (&tty_driver.ttys and
     522             :  *      &tty_driver.termios), instead use dynamic memory keyed through the
     523             :  *      devpts filesystem. This is only applicable to the PTY driver.
     524             :  *
     525             :  * TTY_DRIVER_HARDWARE_BREAK
     526             :  *      Hardware handles break signals. Pass the requested timeout to the
     527             :  *      &tty_operations.break_ctl instead of using a simple on/off interface.
     528             :  *
     529             :  * TTY_DRIVER_DYNAMIC_ALLOC
     530             :  *      Do not allocate structures which are needed per line for this driver
     531             :  *      (&tty_driver.ports) as it would waste memory. The driver will take
     532             :  *      care. This is only applicable to the PTY driver.
     533             :  *
     534             :  * TTY_DRIVER_UNNUMBERED_NODE
     535             :  *      Do not create numbered ``/dev`` nodes. For example, create
     536             :  *      ``/dev/ttyprintk`` and not ``/dev/ttyprintk0``. Applicable only when a
     537             :  *      driver for a single tty device is being allocated.
     538             :  */
     539             : #define TTY_DRIVER_INSTALLED            0x0001
     540             : #define TTY_DRIVER_RESET_TERMIOS        0x0002
     541             : #define TTY_DRIVER_REAL_RAW             0x0004
     542             : #define TTY_DRIVER_DYNAMIC_DEV          0x0008
     543             : #define TTY_DRIVER_DEVPTS_MEM           0x0010
     544             : #define TTY_DRIVER_HARDWARE_BREAK       0x0020
     545             : #define TTY_DRIVER_DYNAMIC_ALLOC        0x0040
     546             : #define TTY_DRIVER_UNNUMBERED_NODE      0x0080
     547             : 
     548             : /* tty driver types */
     549             : #define TTY_DRIVER_TYPE_SYSTEM          0x0001
     550             : #define TTY_DRIVER_TYPE_CONSOLE         0x0002
     551             : #define TTY_DRIVER_TYPE_SERIAL          0x0003
     552             : #define TTY_DRIVER_TYPE_PTY             0x0004
     553             : #define TTY_DRIVER_TYPE_SCC             0x0005  /* scc driver */
     554             : #define TTY_DRIVER_TYPE_SYSCONS         0x0006
     555             : 
     556             : /* system subtypes (magic, used by tty_io.c) */
     557             : #define SYSTEM_TYPE_TTY                 0x0001
     558             : #define SYSTEM_TYPE_CONSOLE             0x0002
     559             : #define SYSTEM_TYPE_SYSCONS             0x0003
     560             : #define SYSTEM_TYPE_SYSPTMX             0x0004
     561             : 
     562             : /* pty subtypes (magic, used by tty_io.c) */
     563             : #define PTY_TYPE_MASTER                 0x0001
     564             : #define PTY_TYPE_SLAVE                  0x0002
     565             : 
     566             : /* serial subtype definitions */
     567             : #define SERIAL_TYPE_NORMAL      1
     568             : 
     569             : int tty_register_driver(struct tty_driver *driver);
     570             : void tty_unregister_driver(struct tty_driver *driver);
     571             : struct device *tty_register_device(struct tty_driver *driver, unsigned index,
     572             :                 struct device *dev);
     573             : struct device *tty_register_device_attr(struct tty_driver *driver,
     574             :                 unsigned index, struct device *device, void *drvdata,
     575             :                 const struct attribute_group **attr_grp);
     576             : void tty_unregister_device(struct tty_driver *driver, unsigned index);
     577             : 
     578             : #ifdef CONFIG_PROC_FS
     579             : void proc_tty_register_driver(struct tty_driver *);
     580             : void proc_tty_unregister_driver(struct tty_driver *);
     581             : #else
     582             : static inline void proc_tty_register_driver(struct tty_driver *d) {}
     583             : static inline void proc_tty_unregister_driver(struct tty_driver *d) {}
     584             : #endif
     585             : 
     586             : #endif /* #ifdef _LINUX_TTY_DRIVER_H */

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