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       1                 :            : /* SPDX-License-Identifier: GPL-2.0 */
       2                 :            : #ifndef _LINUX_TTY_DRIVER_H
       3                 :            : #define _LINUX_TTY_DRIVER_H
       4                 :            : 
       5                 :            : /*
       6                 :            :  * This structure defines the interface between the low-level tty
       7                 :            :  * driver and the tty routines.  The following routines can be
       8                 :            :  * defined; unless noted otherwise, they are optional, and can be
       9                 :            :  * filled in with a null pointer.
      10                 :            :  *
      11                 :            :  * struct tty_struct * (*lookup)(struct tty_driver *self, struct file *, int idx)
      12                 :            :  *
      13                 :            :  *      Return the tty device corresponding to idx, NULL if there is not
      14                 :            :  *      one currently in use and an ERR_PTR value on error. Called under
      15                 :            :  *      tty_mutex (for now!)
      16                 :            :  *
      17                 :            :  *      Optional method. Default behaviour is to use the ttys array
      18                 :            :  *
      19                 :            :  * int (*install)(struct tty_driver *self, struct tty_struct *tty)
      20                 :            :  *
      21                 :            :  *      Install a new tty into the tty driver internal tables. Used in
      22                 :            :  *      conjunction with lookup and remove methods.
      23                 :            :  *
      24                 :            :  *      Optional method. Default behaviour is to use the ttys array
      25                 :            :  *
      26                 :            :  * void (*remove)(struct tty_driver *self, struct tty_struct *tty)
      27                 :            :  *
      28                 :            :  *      Remove a closed tty from the tty driver internal tables. Used in
      29                 :            :  *      conjunction with lookup and remove methods.
      30                 :            :  *
      31                 :            :  *      Optional method. Default behaviour is to use the ttys array
      32                 :            :  *
      33                 :            :  * int  (*open)(struct tty_struct * tty, struct file * filp);
      34                 :            :  *
      35                 :            :  *      This routine is called when a particular tty device is opened.
      36                 :            :  *      This routine is mandatory; if this routine is not filled in,
      37                 :            :  *      the attempted open will fail with ENODEV.
      38                 :            :  *
      39                 :            :  *      Required method. Called with tty lock held.
      40                 :            :  *
      41                 :            :  * void (*close)(struct tty_struct * tty, struct file * filp);
      42                 :            :  *
      43                 :            :  *      This routine is called when a particular tty device is closed.
      44                 :            :  *      Note: called even if the corresponding open() failed.
      45                 :            :  *
      46                 :            :  *      Required method. Called with tty lock held.
      47                 :            :  *
      48                 :            :  * void (*shutdown)(struct tty_struct * tty);
      49                 :            :  *
      50                 :            :  *      This routine is called under the tty lock when a particular tty device
      51                 :            :  *      is closed for the last time. It executes before the tty resources
      52                 :            :  *      are freed so may execute while another function holds a tty kref.
      53                 :            :  *
      54                 :            :  * void (*cleanup)(struct tty_struct * tty);
      55                 :            :  *
      56                 :            :  *      This routine is called asynchronously when a particular tty device
      57                 :            :  *      is closed for the last time freeing up the resources. This is
      58                 :            :  *      actually the second part of shutdown for routines that might sleep.
      59                 :            :  *
      60                 :            :  *
      61                 :            :  * int (*write)(struct tty_struct * tty,
      62                 :            :  *               const unsigned char *buf, int count);
      63                 :            :  *
      64                 :            :  *      This routine is called by the kernel to write a series of
      65                 :            :  *      characters to the tty device.  The characters may come from
      66                 :            :  *      user space or kernel space.  This routine will return the
      67                 :            :  *      number of characters actually accepted for writing.
      68                 :            :  *
      69                 :            :  *      Optional: Required for writable devices.
      70                 :            :  *
      71                 :            :  * int (*put_char)(struct tty_struct *tty, unsigned char ch);
      72                 :            :  *
      73                 :            :  *      This routine is called by the kernel to write a single
      74                 :            :  *      character to the tty device.  If the kernel uses this routine,
      75                 :            :  *      it must call the flush_chars() routine (if defined) when it is
      76                 :            :  *      done stuffing characters into the driver.  If there is no room
      77                 :            :  *      in the queue, the character is ignored.
      78                 :            :  *
      79                 :            :  *      Optional: Kernel will use the write method if not provided.
      80                 :            :  *
      81                 :            :  *      Note: Do not call this function directly, call tty_put_char
      82                 :            :  *
      83                 :            :  * void (*flush_chars)(struct tty_struct *tty);
      84                 :            :  *
      85                 :            :  *      This routine is called by the kernel after it has written a
      86                 :            :  *      series of characters to the tty device using put_char().  
      87                 :            :  *
      88                 :            :  *      Optional:
      89                 :            :  *
      90                 :            :  *      Note: Do not call this function directly, call tty_driver_flush_chars
      91                 :            :  * 
      92                 :            :  * int  (*write_room)(struct tty_struct *tty);
      93                 :            :  *
      94                 :            :  *      This routine returns the numbers of characters the tty driver
      95                 :            :  *      will accept for queuing to be written.  This number is subject
      96                 :            :  *      to change as output buffers get emptied, or if the output flow
      97                 :            :  *      control is acted.
      98                 :            :  *
      99                 :            :  *      Required if write method is provided else not needed.
     100                 :            :  *
     101                 :            :  *      Note: Do not call this function directly, call tty_write_room
     102                 :            :  * 
     103                 :            :  * int  (*ioctl)(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
     104                 :            :  *
     105                 :            :  *      This routine allows the tty driver to implement
     106                 :            :  *      device-specific ioctls.  If the ioctl number passed in cmd
     107                 :            :  *      is not recognized by the driver, it should return ENOIOCTLCMD.
     108                 :            :  *
     109                 :            :  *      Optional
     110                 :            :  *
     111                 :            :  * long (*compat_ioctl)(struct tty_struct *tty,,
     112                 :            :  *                      unsigned int cmd, unsigned long arg);
     113                 :            :  *
     114                 :            :  *      implement ioctl processing for 32 bit process on 64 bit system
     115                 :            :  *
     116                 :            :  *      Optional
     117                 :            :  * 
     118                 :            :  * void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
     119                 :            :  *
     120                 :            :  *      This routine allows the tty driver to be notified when
     121                 :            :  *      device's termios settings have changed.
     122                 :            :  *
     123                 :            :  *      Optional: Called under the termios lock
     124                 :            :  *
     125                 :            :  *
     126                 :            :  * void (*set_ldisc)(struct tty_struct *tty);
     127                 :            :  *
     128                 :            :  *      This routine allows the tty driver to be notified when the
     129                 :            :  *      device's termios settings have changed.
     130                 :            :  *
     131                 :            :  *      Optional: Called under BKL (currently)
     132                 :            :  * 
     133                 :            :  * void (*throttle)(struct tty_struct * tty);
     134                 :            :  *
     135                 :            :  *      This routine notifies the tty driver that input buffers for
     136                 :            :  *      the line discipline are close to full, and it should somehow
     137                 :            :  *      signal that no more characters should be sent to the tty.
     138                 :            :  *
     139                 :            :  *      Optional: Always invoke via tty_throttle(), called under the
     140                 :            :  *      termios lock.
     141                 :            :  * 
     142                 :            :  * void (*unthrottle)(struct tty_struct * tty);
     143                 :            :  *
     144                 :            :  *      This routine notifies the tty drivers that it should signals
     145                 :            :  *      that characters can now be sent to the tty without fear of
     146                 :            :  *      overrunning the input buffers of the line disciplines.
     147                 :            :  * 
     148                 :            :  *      Optional: Always invoke via tty_unthrottle(), called under the
     149                 :            :  *      termios lock.
     150                 :            :  *
     151                 :            :  * void (*stop)(struct tty_struct *tty);
     152                 :            :  *
     153                 :            :  *      This routine notifies the tty driver that it should stop
     154                 :            :  *      outputting characters to the tty device.  
     155                 :            :  *
     156                 :            :  *      Called with ->flow_lock held. Serialized with start() method.
     157                 :            :  *
     158                 :            :  *      Optional:
     159                 :            :  *
     160                 :            :  *      Note: Call stop_tty not this method.
     161                 :            :  * 
     162                 :            :  * void (*start)(struct tty_struct *tty);
     163                 :            :  *
     164                 :            :  *      This routine notifies the tty driver that it resume sending
     165                 :            :  *      characters to the tty device.
     166                 :            :  *
     167                 :            :  *      Called with ->flow_lock held. Serialized with stop() method.
     168                 :            :  *
     169                 :            :  *      Optional:
     170                 :            :  *
     171                 :            :  *      Note: Call start_tty not this method.
     172                 :            :  * 
     173                 :            :  * void (*hangup)(struct tty_struct *tty);
     174                 :            :  *
     175                 :            :  *      This routine notifies the tty driver that it should hang up the
     176                 :            :  *      tty device.
     177                 :            :  *
     178                 :            :  *      Optional:
     179                 :            :  *
     180                 :            :  *      Called with tty lock held.
     181                 :            :  *
     182                 :            :  * int (*break_ctl)(struct tty_struct *tty, int state);
     183                 :            :  *
     184                 :            :  *      This optional routine requests the tty driver to turn on or
     185                 :            :  *      off BREAK status on the RS-232 port.  If state is -1,
     186                 :            :  *      then the BREAK status should be turned on; if state is 0, then
     187                 :            :  *      BREAK should be turned off.
     188                 :            :  *
     189                 :            :  *      If this routine is implemented, the high-level tty driver will
     190                 :            :  *      handle the following ioctls: TCSBRK, TCSBRKP, TIOCSBRK,
     191                 :            :  *      TIOCCBRK.
     192                 :            :  *
     193                 :            :  *      If the driver sets TTY_DRIVER_HARDWARE_BREAK then the interface
     194                 :            :  *      will also be called with actual times and the hardware is expected
     195                 :            :  *      to do the delay work itself. 0 and -1 are still used for on/off.
     196                 :            :  *
     197                 :            :  *      Optional: Required for TCSBRK/BRKP/etc handling.
     198                 :            :  *
     199                 :            :  * void (*wait_until_sent)(struct tty_struct *tty, int timeout);
     200                 :            :  * 
     201                 :            :  *      This routine waits until the device has written out all of the
     202                 :            :  *      characters in its transmitter FIFO.
     203                 :            :  *
     204                 :            :  *      Optional: If not provided the device is assumed to have no FIFO
     205                 :            :  *
     206                 :            :  *      Note: Usually correct to call tty_wait_until_sent
     207                 :            :  *
     208                 :            :  * void (*send_xchar)(struct tty_struct *tty, char ch);
     209                 :            :  *
     210                 :            :  *      This routine is used to send a high-priority XON/XOFF
     211                 :            :  *      character to the device.
     212                 :            :  *
     213                 :            :  *      Optional: If not provided then the write method is called under
     214                 :            :  *      the atomic write lock to keep it serialized with the ldisc.
     215                 :            :  *
     216                 :            :  * int (*resize)(struct tty_struct *tty, struct winsize *ws)
     217                 :            :  *
     218                 :            :  *      Called when a termios request is issued which changes the
     219                 :            :  *      requested terminal geometry.
     220                 :            :  *
     221                 :            :  *      Optional: the default action is to update the termios structure
     222                 :            :  *      without error. This is usually the correct behaviour. Drivers should
     223                 :            :  *      not force errors here if they are not resizable objects (eg a serial
     224                 :            :  *      line). See tty_do_resize() if you need to wrap the standard method
     225                 :            :  *      in your own logic - the usual case.
     226                 :            :  *
     227                 :            :  * void (*set_termiox)(struct tty_struct *tty, struct termiox *new);
     228                 :            :  *
     229                 :            :  *      Called when the device receives a termiox based ioctl. Passes down
     230                 :            :  *      the requested data from user space. This method will not be invoked
     231                 :            :  *      unless the tty also has a valid tty->termiox pointer.
     232                 :            :  *
     233                 :            :  *      Optional: Called under the termios lock
     234                 :            :  *
     235                 :            :  * int (*get_icount)(struct tty_struct *tty, struct serial_icounter *icount);
     236                 :            :  *
     237                 :            :  *      Called when the device receives a TIOCGICOUNT ioctl. Passed a kernel
     238                 :            :  *      structure to complete. This method is optional and will only be called
     239                 :            :  *      if provided (otherwise EINVAL will be returned).
     240                 :            :  */
     241                 :            : 
     242                 :            : #include <linux/export.h>
     243                 :            : #include <linux/fs.h>
     244                 :            : #include <linux/list.h>
     245                 :            : #include <linux/cdev.h>
     246                 :            : #include <linux/termios.h>
     247                 :            : #include <linux/seq_file.h>
     248                 :            : 
     249                 :            : struct tty_struct;
     250                 :            : struct tty_driver;
     251                 :            : struct serial_icounter_struct;
     252                 :            : struct serial_struct;
     253                 :            : 
     254                 :            : struct tty_operations {
     255                 :            :         struct tty_struct * (*lookup)(struct tty_driver *driver,
     256                 :            :                         struct file *filp, int idx);
     257                 :            :         int  (*install)(struct tty_driver *driver, struct tty_struct *tty);
     258                 :            :         void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
     259                 :            :         int  (*open)(struct tty_struct * tty, struct file * filp);
     260                 :            :         void (*close)(struct tty_struct * tty, struct file * filp);
     261                 :            :         void (*shutdown)(struct tty_struct *tty);
     262                 :            :         void (*cleanup)(struct tty_struct *tty);
     263                 :            :         int  (*write)(struct tty_struct * tty,
     264                 :            :                       const unsigned char *buf, int count);
     265                 :            :         int  (*put_char)(struct tty_struct *tty, unsigned char ch);
     266                 :            :         void (*flush_chars)(struct tty_struct *tty);
     267                 :            :         int  (*write_room)(struct tty_struct *tty);
     268                 :            :         int  (*chars_in_buffer)(struct tty_struct *tty);
     269                 :            :         int  (*ioctl)(struct tty_struct *tty,
     270                 :            :                     unsigned int cmd, unsigned long arg);
     271                 :            :         long (*compat_ioctl)(struct tty_struct *tty,
     272                 :            :                              unsigned int cmd, unsigned long arg);
     273                 :            :         void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
     274                 :            :         void (*throttle)(struct tty_struct * tty);
     275                 :            :         void (*unthrottle)(struct tty_struct * tty);
     276                 :            :         void (*stop)(struct tty_struct *tty);
     277                 :            :         void (*start)(struct tty_struct *tty);
     278                 :            :         void (*hangup)(struct tty_struct *tty);
     279                 :            :         int (*break_ctl)(struct tty_struct *tty, int state);
     280                 :            :         void (*flush_buffer)(struct tty_struct *tty);
     281                 :            :         void (*set_ldisc)(struct tty_struct *tty);
     282                 :            :         void (*wait_until_sent)(struct tty_struct *tty, int timeout);
     283                 :            :         void (*send_xchar)(struct tty_struct *tty, char ch);
     284                 :            :         int (*tiocmget)(struct tty_struct *tty);
     285                 :            :         int (*tiocmset)(struct tty_struct *tty,
     286                 :            :                         unsigned int set, unsigned int clear);
     287                 :            :         int (*resize)(struct tty_struct *tty, struct winsize *ws);
     288                 :            :         int (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);
     289                 :            :         int (*get_icount)(struct tty_struct *tty,
     290                 :            :                                 struct serial_icounter_struct *icount);
     291                 :            :         int  (*get_serial)(struct tty_struct *tty, struct serial_struct *p);
     292                 :            :         int  (*set_serial)(struct tty_struct *tty, struct serial_struct *p);
     293                 :            :         void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m);
     294                 :            : #ifdef CONFIG_CONSOLE_POLL
     295                 :            :         int (*poll_init)(struct tty_driver *driver, int line, char *options);
     296                 :            :         int (*poll_get_char)(struct tty_driver *driver, int line);
     297                 :            :         void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
     298                 :            : #endif
     299                 :            :         int (*proc_show)(struct seq_file *, void *);
     300                 :            : } __randomize_layout;
     301                 :            : 
     302                 :            : struct tty_driver {
     303                 :            :         int     magic;          /* magic number for this structure */
     304                 :            :         struct kref kref;       /* Reference management */
     305                 :            :         struct cdev **cdevs;
     306                 :            :         struct module   *owner;
     307                 :            :         const char      *driver_name;
     308                 :            :         const char      *name;
     309                 :            :         int     name_base;      /* offset of printed name */
     310                 :            :         int     major;          /* major device number */
     311                 :            :         int     minor_start;    /* start of minor device number */
     312                 :            :         unsigned int    num;    /* number of devices allocated */
     313                 :            :         short   type;           /* type of tty driver */
     314                 :            :         short   subtype;        /* subtype of tty driver */
     315                 :            :         struct ktermios init_termios; /* Initial termios */
     316                 :            :         unsigned long   flags;          /* tty driver flags */
     317                 :            :         struct proc_dir_entry *proc_entry; /* /proc fs entry */
     318                 :            :         struct tty_driver *other; /* only used for the PTY driver */
     319                 :            : 
     320                 :            :         /*
     321                 :            :          * Pointer to the tty data structures
     322                 :            :          */
     323                 :            :         struct tty_struct **ttys;
     324                 :            :         struct tty_port **ports;
     325                 :            :         struct ktermios **termios;
     326                 :            :         void *driver_state;
     327                 :            : 
     328                 :            :         /*
     329                 :            :          * Driver methods
     330                 :            :          */
     331                 :            : 
     332                 :            :         const struct tty_operations *ops;
     333                 :            :         struct list_head tty_drivers;
     334                 :            : } __randomize_layout;
     335                 :            : 
     336                 :            : extern struct list_head tty_drivers;
     337                 :            : 
     338                 :            : extern struct tty_driver *__tty_alloc_driver(unsigned int lines,
     339                 :            :                 struct module *owner, unsigned long flags);
     340                 :            : extern void put_tty_driver(struct tty_driver *driver);
     341                 :            : extern void tty_set_operations(struct tty_driver *driver,
     342                 :            :                         const struct tty_operations *op);
     343                 :            : extern struct tty_driver *tty_find_polling_driver(char *name, int *line);
     344                 :            : 
     345                 :            : extern void tty_driver_kref_put(struct tty_driver *driver);
     346                 :            : 
     347                 :            : /* Use TTY_DRIVER_* flags below */
     348                 :            : #define tty_alloc_driver(lines, flags) \
     349                 :            :                 __tty_alloc_driver(lines, THIS_MODULE, flags)
     350                 :            : 
     351                 :            : /*
     352                 :            :  * DEPRECATED Do not use this in new code, use tty_alloc_driver instead.
     353                 :            :  * (And change the return value checks.)
     354                 :            :  */
     355                 :            : static inline struct tty_driver *alloc_tty_driver(unsigned int lines)
     356                 :            : {
     357                 :          3 :         struct tty_driver *ret = tty_alloc_driver(lines, 0);
     358                 :          3 :         if (IS_ERR(ret))
     359                 :            :                 return NULL;
     360                 :            :         return ret;
     361                 :            : }
     362                 :            : 
     363                 :            : static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
     364                 :            : {
     365                 :            :         kref_get(&d->kref);
     366                 :            :         return d;
     367                 :            : }
     368                 :            : 
     369                 :            : /* tty driver magic number */
     370                 :            : #define TTY_DRIVER_MAGIC                0x5402
     371                 :            : 
     372                 :            : /*
     373                 :            :  * tty driver flags
     374                 :            :  * 
     375                 :            :  * TTY_DRIVER_RESET_TERMIOS --- requests the tty layer to reset the
     376                 :            :  *      termios setting when the last process has closed the device.
     377                 :            :  *      Used for PTY's, in particular.
     378                 :            :  * 
     379                 :            :  * TTY_DRIVER_REAL_RAW --- if set, indicates that the driver will
     380                 :            :  *      guarantee never not to set any special character handling
     381                 :            :  *      flags if ((IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR ||
     382                 :            :  *      !INPCK)).  That is, if there is no reason for the driver to
     383                 :            :  *      send notifications of parity and break characters up to the
     384                 :            :  *      line driver, it won't do so.  This allows the line driver to
     385                 :            :  *      optimize for this case if this flag is set.  (Note that there
     386                 :            :  *      is also a promise, if the above case is true, not to signal
     387                 :            :  *      overruns, either.)
     388                 :            :  *
     389                 :            :  * TTY_DRIVER_DYNAMIC_DEV --- if set, the individual tty devices need
     390                 :            :  *      to be registered with a call to tty_register_device() when the
     391                 :            :  *      device is found in the system and unregistered with a call to
     392                 :            :  *      tty_unregister_device() so the devices will be show up
     393                 :            :  *      properly in sysfs.  If not set, driver->num entries will be
     394                 :            :  *      created by the tty core in sysfs when tty_register_driver() is
     395                 :            :  *      called.  This is to be used by drivers that have tty devices
     396                 :            :  *      that can appear and disappear while the main tty driver is
     397                 :            :  *      registered with the tty core.
     398                 :            :  *
     399                 :            :  * TTY_DRIVER_DEVPTS_MEM -- don't use the standard arrays, instead
     400                 :            :  *      use dynamic memory keyed through the devpts filesystem.  This
     401                 :            :  *      is only applicable to the pty driver.
     402                 :            :  *
     403                 :            :  * TTY_DRIVER_HARDWARE_BREAK -- hardware handles break signals. Pass
     404                 :            :  *      the requested timeout to the caller instead of using a simple
     405                 :            :  *      on/off interface.
     406                 :            :  *
     407                 :            :  * TTY_DRIVER_DYNAMIC_ALLOC -- do not allocate structures which are
     408                 :            :  *      needed per line for this driver as it would waste memory.
     409                 :            :  *      The driver will take care.
     410                 :            :  *
     411                 :            :  * TTY_DRIVER_UNNUMBERED_NODE -- do not create numbered /dev nodes. In
     412                 :            :  *      other words create /dev/ttyprintk and not /dev/ttyprintk0.
     413                 :            :  *      Applicable only when a driver for a single tty device is
     414                 :            :  *      being allocated.
     415                 :            :  */
     416                 :            : #define TTY_DRIVER_INSTALLED            0x0001
     417                 :            : #define TTY_DRIVER_RESET_TERMIOS        0x0002
     418                 :            : #define TTY_DRIVER_REAL_RAW             0x0004
     419                 :            : #define TTY_DRIVER_DYNAMIC_DEV          0x0008
     420                 :            : #define TTY_DRIVER_DEVPTS_MEM           0x0010
     421                 :            : #define TTY_DRIVER_HARDWARE_BREAK       0x0020
     422                 :            : #define TTY_DRIVER_DYNAMIC_ALLOC        0x0040
     423                 :            : #define TTY_DRIVER_UNNUMBERED_NODE      0x0080
     424                 :            : 
     425                 :            : /* tty driver types */
     426                 :            : #define TTY_DRIVER_TYPE_SYSTEM          0x0001
     427                 :            : #define TTY_DRIVER_TYPE_CONSOLE         0x0002
     428                 :            : #define TTY_DRIVER_TYPE_SERIAL          0x0003
     429                 :            : #define TTY_DRIVER_TYPE_PTY             0x0004
     430                 :            : #define TTY_DRIVER_TYPE_SCC             0x0005  /* scc driver */
     431                 :            : #define TTY_DRIVER_TYPE_SYSCONS         0x0006
     432                 :            : 
     433                 :            : /* system subtypes (magic, used by tty_io.c) */
     434                 :            : #define SYSTEM_TYPE_TTY                 0x0001
     435                 :            : #define SYSTEM_TYPE_CONSOLE             0x0002
     436                 :            : #define SYSTEM_TYPE_SYSCONS             0x0003
     437                 :            : #define SYSTEM_TYPE_SYSPTMX             0x0004
     438                 :            : 
     439                 :            : /* pty subtypes (magic, used by tty_io.c) */
     440                 :            : #define PTY_TYPE_MASTER                 0x0001
     441                 :            : #define PTY_TYPE_SLAVE                  0x0002
     442                 :            : 
     443                 :            : /* serial subtype definitions */
     444                 :            : #define SERIAL_TYPE_NORMAL      1
     445                 :            : 
     446                 :            : #endif /* #ifdef _LINUX_TTY_DRIVER_H */