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