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