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 */ alloc_tty_driver(unsigned int lines)355 static inline struct tty_driver *alloc_tty_driver(unsigned int lines) 356 { 357 struct tty_driver *ret = tty_alloc_driver(lines, 0); 358 if (IS_ERR(ret)) 359 return NULL; 360 return ret; 361 } 362 tty_driver_kref_get(struct tty_driver * d)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 */ 447