linux/include/linux/tty_driver.h
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   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, 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.
  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.
  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 *      Optional:
 156 *
 157 *      Note: Call stop_tty not this method.
 158 * 
 159 * void (*start)(struct tty_struct *tty);
 160 *
 161 *      This routine notifies the tty driver that it resume sending
 162 *      characters to the tty device.
 163 *
 164 *      Optional:
 165 *
 166 *      Note: Call start_tty not this method.
 167 * 
 168 * void (*hangup)(struct tty_struct *tty);
 169 *
 170 *      This routine notifies the tty driver that it should hang up the
 171 *      tty device.
 172 *
 173 *      Optional:
 174 *
 175 * int (*break_ctl)(struct tty_struct *tty, int state);
 176 *
 177 *      This optional routine requests the tty driver to turn on or
 178 *      off BREAK status on the RS-232 port.  If state is -1,
 179 *      then the BREAK status should be turned on; if state is 0, then
 180 *      BREAK should be turned off.
 181 *
 182 *      If this routine is implemented, the high-level tty driver will
 183 *      handle the following ioctls: TCSBRK, TCSBRKP, TIOCSBRK,
 184 *      TIOCCBRK.
 185 *
 186 *      If the driver sets TTY_DRIVER_HARDWARE_BREAK then the interface
 187 *      will also be called with actual times and the hardware is expected
 188 *      to do the delay work itself. 0 and -1 are still used for on/off.
 189 *
 190 *      Optional: Required for TCSBRK/BRKP/etc handling.
 191 *
 192 * void (*wait_until_sent)(struct tty_struct *tty, int timeout);
 193 * 
 194 *      This routine waits until the device has written out all of the
 195 *      characters in its transmitter FIFO.
 196 *
 197 *      Optional: If not provided the device is assumed to have no FIFO
 198 *
 199 *      Note: Usually correct to call tty_wait_until_sent
 200 *
 201 * void (*send_xchar)(struct tty_struct *tty, char ch);
 202 *
 203 *      This routine is used to send a high-priority XON/XOFF
 204 *      character to the device.
 205 *
 206 *      Optional: If not provided then the write method is called under
 207 *      the atomic write lock to keep it serialized with the ldisc.
 208 *
 209 * int (*resize)(struct tty_struct *tty, struct winsize *ws)
 210 *
 211 *      Called when a termios request is issued which changes the
 212 *      requested terminal geometry.
 213 *
 214 *      Optional: the default action is to update the termios structure
 215 *      without error. This is usually the correct behaviour. Drivers should
 216 *      not force errors here if they are not resizable objects (eg a serial
 217 *      line). See tty_do_resize() if you need to wrap the standard method
 218 *      in your own logic - the usual case.
 219 *
 220 * void (*set_termiox)(struct tty_struct *tty, struct termiox *new);
 221 *
 222 *      Called when the device receives a termiox based ioctl. Passes down
 223 *      the requested data from user space. This method will not be invoked
 224 *      unless the tty also has a valid tty->termiox pointer.
 225 *
 226 *      Optional: Called under the termios lock
 227 *
 228 * int (*get_icount)(struct tty_struct *tty, struct serial_icounter *icount);
 229 *
 230 *      Called when the device receives a TIOCGICOUNT ioctl. Passed a kernel
 231 *      structure to complete. This method is optional and will only be called
 232 *      if provided (otherwise EINVAL will be returned).
 233 */
 234
 235#include <linux/export.h>
 236#include <linux/fs.h>
 237#include <linux/list.h>
 238#include <linux/cdev.h>
 239#include <linux/termios.h>
 240
 241struct tty_struct;
 242struct tty_driver;
 243struct serial_icounter_struct;
 244
 245struct tty_operations {
 246        struct tty_struct * (*lookup)(struct tty_driver *driver,
 247                        struct inode *inode, int idx);
 248        int  (*install)(struct tty_driver *driver, struct tty_struct *tty);
 249        void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
 250        int  (*open)(struct tty_struct * tty, struct file * filp);
 251        void (*close)(struct tty_struct * tty, struct file * filp);
 252        void (*shutdown)(struct tty_struct *tty);
 253        void (*cleanup)(struct tty_struct *tty);
 254        int  (*write)(struct tty_struct * tty,
 255                      const unsigned char *buf, int count);
 256        int  (*put_char)(struct tty_struct *tty, unsigned char ch);
 257        void (*flush_chars)(struct tty_struct *tty);
 258        int  (*write_room)(struct tty_struct *tty);
 259        int  (*chars_in_buffer)(struct tty_struct *tty);
 260        int  (*ioctl)(struct tty_struct *tty,
 261                    unsigned int cmd, unsigned long arg);
 262        long (*compat_ioctl)(struct tty_struct *tty,
 263                             unsigned int cmd, unsigned long arg);
 264        void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
 265        void (*throttle)(struct tty_struct * tty);
 266        void (*unthrottle)(struct tty_struct * tty);
 267        void (*stop)(struct tty_struct *tty);
 268        void (*start)(struct tty_struct *tty);
 269        void (*hangup)(struct tty_struct *tty);
 270        int (*break_ctl)(struct tty_struct *tty, int state);
 271        void (*flush_buffer)(struct tty_struct *tty);
 272        void (*set_ldisc)(struct tty_struct *tty);
 273        void (*wait_until_sent)(struct tty_struct *tty, int timeout);
 274        void (*send_xchar)(struct tty_struct *tty, char ch);
 275        int (*tiocmget)(struct tty_struct *tty);
 276        int (*tiocmset)(struct tty_struct *tty,
 277                        unsigned int set, unsigned int clear);
 278        int (*resize)(struct tty_struct *tty, struct winsize *ws);
 279        int (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);
 280        int (*get_icount)(struct tty_struct *tty,
 281                                struct serial_icounter_struct *icount);
 282#ifdef CONFIG_CONSOLE_POLL
 283        int (*poll_init)(struct tty_driver *driver, int line, char *options);
 284        int (*poll_get_char)(struct tty_driver *driver, int line);
 285        void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
 286#endif
 287        const struct file_operations *proc_fops;
 288};
 289
 290struct tty_driver {
 291        int     magic;          /* magic number for this structure */
 292        struct kref kref;       /* Reference management */
 293        struct cdev *cdevs;
 294        struct module   *owner;
 295        const char      *driver_name;
 296        const char      *name;
 297        int     name_base;      /* offset of printed name */
 298        int     major;          /* major device number */
 299        int     minor_start;    /* start of minor device number */
 300        unsigned int    num;    /* number of devices allocated */
 301        short   type;           /* type of tty driver */
 302        short   subtype;        /* subtype of tty driver */
 303        struct ktermios init_termios; /* Initial termios */
 304        unsigned long   flags;          /* tty driver flags */
 305        struct proc_dir_entry *proc_entry; /* /proc fs entry */
 306        struct tty_driver *other; /* only used for the PTY driver */
 307
 308        /*
 309         * Pointer to the tty data structures
 310         */
 311        struct tty_struct **ttys;
 312        struct tty_port **ports;
 313        struct ktermios **termios;
 314        void *driver_state;
 315
 316        /*
 317         * Driver methods
 318         */
 319
 320        const struct tty_operations *ops;
 321        struct list_head tty_drivers;
 322};
 323
 324extern struct list_head tty_drivers;
 325
 326extern struct tty_driver *__tty_alloc_driver(unsigned int lines,
 327                struct module *owner, unsigned long flags);
 328extern void put_tty_driver(struct tty_driver *driver);
 329extern void tty_set_operations(struct tty_driver *driver,
 330                        const struct tty_operations *op);
 331extern struct tty_driver *tty_find_polling_driver(char *name, int *line);
 332
 333extern void tty_driver_kref_put(struct tty_driver *driver);
 334
 335/* Use TTY_DRIVER_* flags below */
 336#define tty_alloc_driver(lines, flags) \
 337                __tty_alloc_driver(lines, THIS_MODULE, flags)
 338
 339/*
 340 * DEPRECATED Do not use this in new code, use tty_alloc_driver instead.
 341 * (And change the return value checks.)
 342 */
 343static inline struct tty_driver *alloc_tty_driver(unsigned int lines)
 344{
 345        struct tty_driver *ret = tty_alloc_driver(lines, 0);
 346        if (IS_ERR(ret))
 347                return NULL;
 348        return ret;
 349}
 350
 351static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
 352{
 353        kref_get(&d->kref);
 354        return d;
 355}
 356
 357/* tty driver magic number */
 358#define TTY_DRIVER_MAGIC                0x5402
 359
 360/*
 361 * tty driver flags
 362 * 
 363 * TTY_DRIVER_RESET_TERMIOS --- requests the tty layer to reset the
 364 *      termios setting when the last process has closed the device.
 365 *      Used for PTY's, in particular.
 366 * 
 367 * TTY_DRIVER_REAL_RAW --- if set, indicates that the driver will
 368 *      guarantee never not to set any special character handling
 369 *      flags if ((IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR ||
 370 *      !INPCK)).  That is, if there is no reason for the driver to
 371 *      send notifications of parity and break characters up to the
 372 *      line driver, it won't do so.  This allows the line driver to
 373 *      optimize for this case if this flag is set.  (Note that there
 374 *      is also a promise, if the above case is true, not to signal
 375 *      overruns, either.)
 376 *
 377 * TTY_DRIVER_DYNAMIC_DEV --- if set, the individual tty devices need
 378 *      to be registered with a call to tty_register_device() when the
 379 *      device is found in the system and unregistered with a call to
 380 *      tty_unregister_device() so the devices will be show up
 381 *      properly in sysfs.  If not set, driver->num entries will be
 382 *      created by the tty core in sysfs when tty_register_driver() is
 383 *      called.  This is to be used by drivers that have tty devices
 384 *      that can appear and disappear while the main tty driver is
 385 *      registered with the tty core.
 386 *
 387 * TTY_DRIVER_DEVPTS_MEM -- don't use the standard arrays, instead
 388 *      use dynamic memory keyed through the devpts filesystem.  This
 389 *      is only applicable to the pty driver.
 390 *
 391 * TTY_DRIVER_HARDWARE_BREAK -- hardware handles break signals. Pass
 392 *      the requested timeout to the caller instead of using a simple
 393 *      on/off interface.
 394 *
 395 * TTY_DRIVER_DYNAMIC_ALLOC -- do not allocate structures which are
 396 *      needed per line for this driver as it would waste memory.
 397 *      The driver will take care.
 398 *
 399 * TTY_DRIVER_UNNUMBERED_NODE -- do not create numbered /dev nodes. In
 400 *      other words create /dev/ttyprintk and not /dev/ttyprintk0.
 401 *      Applicable only when a driver for a single tty device is
 402 *      being allocated.
 403 */
 404#define TTY_DRIVER_INSTALLED            0x0001
 405#define TTY_DRIVER_RESET_TERMIOS        0x0002
 406#define TTY_DRIVER_REAL_RAW             0x0004
 407#define TTY_DRIVER_DYNAMIC_DEV          0x0008
 408#define TTY_DRIVER_DEVPTS_MEM           0x0010
 409#define TTY_DRIVER_HARDWARE_BREAK       0x0020
 410#define TTY_DRIVER_DYNAMIC_ALLOC        0x0040
 411#define TTY_DRIVER_UNNUMBERED_NODE      0x0080
 412
 413/* tty driver types */
 414#define TTY_DRIVER_TYPE_SYSTEM          0x0001
 415#define TTY_DRIVER_TYPE_CONSOLE         0x0002
 416#define TTY_DRIVER_TYPE_SERIAL          0x0003
 417#define TTY_DRIVER_TYPE_PTY             0x0004
 418#define TTY_DRIVER_TYPE_SCC             0x0005  /* scc driver */
 419#define TTY_DRIVER_TYPE_SYSCONS         0x0006
 420
 421/* system subtypes (magic, used by tty_io.c) */
 422#define SYSTEM_TYPE_TTY                 0x0001
 423#define SYSTEM_TYPE_CONSOLE             0x0002
 424#define SYSTEM_TYPE_SYSCONS             0x0003
 425#define SYSTEM_TYPE_SYSPTMX             0x0004
 426
 427/* pty subtypes (magic, used by tty_io.c) */
 428#define PTY_TYPE_MASTER                 0x0001
 429#define PTY_TYPE_SLAVE                  0x0002
 430
 431/* serial subtype definitions */
 432#define SERIAL_TYPE_NORMAL      1
 433
 434#endif /* #ifdef _LINUX_TTY_DRIVER_H */
 435
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