include/linux/tty_driver.h

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