1 /* 2 * linux/include/linux/console.h 3 * 4 * Copyright (C) 1993 Hamish Macdonald 5 * 6 * This file is subject to the terms and conditions of the GNU General Public 7 * License. See the file COPYING in the main directory of this archive 8 * for more details. 9 * 10 * Changed: 11 * 10-Mar-94: Arno Griffioen: Conversion for vt100 emulator port from PC LINUX 12 */ 13 14 #ifndef _LINUX_CONSOLE_H_ 15 #define _LINUX_CONSOLE_H_ 1 16 17 #include <linux/atomic.h> 18 #include <linux/bits.h> 19 #include <linux/irq_work.h> 20 #include <linux/rculist.h> 21 #include <linux/rcuwait.h> 22 #include <linux/types.h> 23 #include <linux/vesa.h> 24 25 struct vc_data; 26 struct console_font_op; 27 struct console_font; 28 struct module; 29 struct tty_struct; 30 struct notifier_block; 31 32 enum con_scroll { 33 SM_UP, 34 SM_DOWN, 35 }; 36 37 enum vc_intensity; 38 39 /** 40 * struct consw - callbacks for consoles 41 * 42 * @owner: the module to get references of when this console is used 43 * @con_startup: set up the console and return its name (like VGA, EGA, ...) 44 * @con_init: initialize the console on @vc. @init is true for the very first 45 * call on this @vc. 46 * @con_deinit: deinitialize the console from @vc. 47 * @con_clear: erase @count characters at [@x, @y] on @vc. @count >= 1. 48 * @con_putc: emit one character with attributes @ca to [@x, @y] on @vc. 49 * (optional -- @con_putcs would be called instead) 50 * @con_putcs: emit @count characters with attributes @s to [@x, @y] on @vc. 51 * @con_cursor: enable/disable cursor depending on @enable 52 * @con_scroll: move lines from @top to @bottom in direction @dir by @lines. 53 * Return true if no generic handling should be done. 54 * Invoked by csi_M and printing to the console. 55 * @con_switch: notifier about the console switch; it is supposed to return 56 * true if a redraw is needed. 57 * @con_blank: blank/unblank the console. The target mode is passed in @blank. 58 * @mode_switch is set if changing from/to text/graphics. The hook 59 * is supposed to return true if a redraw is needed. 60 * @con_font_set: set console @vc font to @font with height @vpitch. @flags can 61 * be %KD_FONT_FLAG_DONT_RECALC. (optional) 62 * @con_font_get: fetch the current font on @vc of height @vpitch into @font. 63 * (optional) 64 * @con_font_default: set default font on @vc. @name can be %NULL or font name 65 * to search for. @font can be filled back. (optional) 66 * @con_resize: resize the @vc console to @width x @height. @from_user is true 67 * when this change comes from the user space. 68 * @con_set_palette: sets the palette of the console @vc to @table (optional) 69 * @con_scrolldelta: the contents of the console should be scrolled by @lines. 70 * Invoked by user. (optional) 71 * @con_set_origin: set origin (see &vc_data::vc_origin) of the @vc. If not 72 * provided or returns false, the origin is set to 73 * @vc->vc_screenbuf. (optional) 74 * @con_save_screen: save screen content into @vc->vc_screenbuf. Called e.g. 75 * upon entering graphics. (optional) 76 * @con_build_attr: build attributes based on @color, @intensity and other 77 * parameters. The result is used for both normal and erase 78 * characters. (optional) 79 * @con_invert_region: invert a region of length @count on @vc starting at @p. 80 * (optional) 81 * @con_debug_enter: prepare the console for the debugger. This includes, but 82 * is not limited to, unblanking the console, loading an 83 * appropriate palette, and allowing debugger generated output. 84 * (optional) 85 * @con_debug_leave: restore the console to its pre-debug state as closely as 86 * possible. (optional) 87 */ 88 struct consw { 89 struct module *owner; 90 const char *(*con_startup)(void); 91 void (*con_init)(struct vc_data *vc, bool init); 92 void (*con_deinit)(struct vc_data *vc); 93 void (*con_clear)(struct vc_data *vc, unsigned int y, 94 unsigned int x, unsigned int count); 95 void (*con_putc)(struct vc_data *vc, u16 ca, unsigned int y, 96 unsigned int x); 97 void (*con_putcs)(struct vc_data *vc, const u16 *s, 98 unsigned int count, unsigned int ypos, 99 unsigned int xpos); 100 void (*con_cursor)(struct vc_data *vc, bool enable); 101 bool (*con_scroll)(struct vc_data *vc, unsigned int top, 102 unsigned int bottom, enum con_scroll dir, 103 unsigned int lines); 104 bool (*con_switch)(struct vc_data *vc); 105 bool (*con_blank)(struct vc_data *vc, enum vesa_blank_mode blank, 106 bool mode_switch); 107 int (*con_font_set)(struct vc_data *vc, 108 const struct console_font *font, 109 unsigned int vpitch, unsigned int flags); 110 int (*con_font_get)(struct vc_data *vc, struct console_font *font, 111 unsigned int vpitch); 112 int (*con_font_default)(struct vc_data *vc, 113 struct console_font *font, const char *name); 114 int (*con_resize)(struct vc_data *vc, unsigned int width, 115 unsigned int height, bool from_user); 116 void (*con_set_palette)(struct vc_data *vc, 117 const unsigned char *table); 118 void (*con_scrolldelta)(struct vc_data *vc, int lines); 119 bool (*con_set_origin)(struct vc_data *vc); 120 void (*con_save_screen)(struct vc_data *vc); 121 u8 (*con_build_attr)(struct vc_data *vc, u8 color, 122 enum vc_intensity intensity, 123 bool blink, bool underline, bool reverse, bool italic); 124 void (*con_invert_region)(struct vc_data *vc, u16 *p, int count); 125 void (*con_debug_enter)(struct vc_data *vc); 126 void (*con_debug_leave)(struct vc_data *vc); 127 }; 128 129 extern const struct consw *conswitchp; 130 131 extern const struct consw dummy_con; /* dummy console buffer */ 132 extern const struct consw vga_con; /* VGA text console */ 133 extern const struct consw newport_con; /* SGI Newport console */ 134 135 struct screen_info; 136 #ifdef CONFIG_VGA_CONSOLE 137 void vgacon_register_screen(struct screen_info *si); 138 #else 139 static inline void vgacon_register_screen(struct screen_info *si) { } 140 #endif 141 142 int con_is_bound(const struct consw *csw); 143 int do_unregister_con_driver(const struct consw *csw); 144 int do_take_over_console(const struct consw *sw, int first, int last, int deflt); 145 void give_up_console(const struct consw *sw); 146 #ifdef CONFIG_VT 147 void con_debug_enter(struct vc_data *vc); 148 void con_debug_leave(void); 149 #else 150 static inline void con_debug_enter(struct vc_data *vc) { } 151 static inline void con_debug_leave(void) { } 152 #endif 153 154 /* 155 * The interface for a console, or any other device that wants to capture 156 * console messages (printer driver?) 157 */ 158 159 /** 160 * enum cons_flags - General console flags 161 * @CON_PRINTBUFFER: Used by newly registered consoles to avoid duplicate 162 * output of messages that were already shown by boot 163 * consoles or read by userspace via syslog() syscall. 164 * @CON_CONSDEV: Indicates that the console driver is backing 165 * /dev/console. 166 * @CON_ENABLED: Indicates if a console is allowed to print records. If 167 * false, the console also will not advance to later 168 * records. 169 * @CON_BOOT: Marks the console driver as early console driver which 170 * is used during boot before the real driver becomes 171 * available. It will be automatically unregistered 172 * when the real console driver is registered unless 173 * "keep_bootcon" parameter is used. 174 * @CON_ANYTIME: A misnomed historical flag which tells the core code 175 * that the legacy @console::write callback can be invoked 176 * on a CPU which is marked OFFLINE. That is misleading as 177 * it suggests that there is no contextual limit for 178 * invoking the callback. The original motivation was 179 * readiness of the per-CPU areas. 180 * @CON_BRL: Indicates a braille device which is exempt from 181 * receiving the printk spam for obvious reasons. 182 * @CON_EXTENDED: The console supports the extended output format of 183 * /dev/kmesg which requires a larger output buffer. 184 * @CON_SUSPENDED: Indicates if a console is suspended. If true, the 185 * printing callbacks must not be called. 186 * @CON_NBCON: Console can operate outside of the legacy style console_lock 187 * constraints. 188 */ 189 enum cons_flags { 190 CON_PRINTBUFFER = BIT(0), 191 CON_CONSDEV = BIT(1), 192 CON_ENABLED = BIT(2), 193 CON_BOOT = BIT(3), 194 CON_ANYTIME = BIT(4), 195 CON_BRL = BIT(5), 196 CON_EXTENDED = BIT(6), 197 CON_SUSPENDED = BIT(7), 198 CON_NBCON = BIT(8), 199 }; 200 201 /** 202 * struct nbcon_state - console state for nbcon consoles 203 * @atom: Compound of the state fields for atomic operations 204 * 205 * @req_prio: The priority of a handover request 206 * @prio: The priority of the current owner 207 * @unsafe: Console is busy in a non takeover region 208 * @unsafe_takeover: A hostile takeover in an unsafe state happened in the 209 * past. The console cannot be safe until re-initialized. 210 * @cpu: The CPU on which the owner runs 211 * 212 * To be used for reading and preparing of the value stored in the nbcon 213 * state variable @console::nbcon_state. 214 * 215 * The @prio and @req_prio fields are particularly important to allow 216 * spin-waiting to timeout and give up without the risk of a waiter being 217 * assigned the lock after giving up. 218 */ 219 struct nbcon_state { 220 union { 221 unsigned int atom; 222 struct { 223 unsigned int prio : 2; 224 unsigned int req_prio : 2; 225 unsigned int unsafe : 1; 226 unsigned int unsafe_takeover : 1; 227 unsigned int cpu : 24; 228 }; 229 }; 230 }; 231 232 /* 233 * The nbcon_state struct is used to easily create and interpret values that 234 * are stored in the @console::nbcon_state variable. Ensure this struct stays 235 * within the size boundaries of the atomic variable's underlying type in 236 * order to avoid any accidental truncation. 237 */ 238 static_assert(sizeof(struct nbcon_state) <= sizeof(int)); 239 240 /** 241 * enum nbcon_prio - console owner priority for nbcon consoles 242 * @NBCON_PRIO_NONE: Unused 243 * @NBCON_PRIO_NORMAL: Normal (non-emergency) usage 244 * @NBCON_PRIO_EMERGENCY: Emergency output (WARN/OOPS...) 245 * @NBCON_PRIO_PANIC: Panic output 246 * @NBCON_PRIO_MAX: The number of priority levels 247 * 248 * A higher priority context can takeover the console when it is 249 * in the safe state. The final attempt to flush consoles in panic() 250 * can be allowed to do so even in an unsafe state (Hope and pray). 251 */ 252 enum nbcon_prio { 253 NBCON_PRIO_NONE = 0, 254 NBCON_PRIO_NORMAL, 255 NBCON_PRIO_EMERGENCY, 256 NBCON_PRIO_PANIC, 257 NBCON_PRIO_MAX, 258 }; 259 260 struct console; 261 struct printk_buffers; 262 263 /** 264 * struct nbcon_context - Context for console acquire/release 265 * @console: The associated console 266 * @spinwait_max_us: Limit for spin-wait acquire 267 * @prio: Priority of the context 268 * @allow_unsafe_takeover: Allow performing takeover even if unsafe. Can 269 * be used only with NBCON_PRIO_PANIC @prio. It 270 * might cause a system freeze when the console 271 * is used later. 272 * @backlog: Ringbuffer has pending records 273 * @pbufs: Pointer to the text buffer for this context 274 * @seq: The sequence number to print for this context 275 */ 276 struct nbcon_context { 277 /* members set by caller */ 278 struct console *console; 279 unsigned int spinwait_max_us; 280 enum nbcon_prio prio; 281 unsigned int allow_unsafe_takeover : 1; 282 283 /* members set by emit */ 284 unsigned int backlog : 1; 285 286 /* members set by acquire */ 287 struct printk_buffers *pbufs; 288 u64 seq; 289 }; 290 291 /** 292 * struct nbcon_write_context - Context handed to the nbcon write callbacks 293 * @ctxt: The core console context 294 * @outbuf: Pointer to the text buffer for output 295 * @len: Length to write 296 * @unsafe_takeover: If a hostile takeover in an unsafe state has occurred 297 */ 298 struct nbcon_write_context { 299 struct nbcon_context __private ctxt; 300 char *outbuf; 301 unsigned int len; 302 bool unsafe_takeover; 303 }; 304 305 /** 306 * struct console - The console descriptor structure 307 * @name: The name of the console driver 308 * @write: Legacy write callback to output messages (Optional) 309 * @read: Read callback for console input (Optional) 310 * @device: The underlying TTY device driver (Optional) 311 * @unblank: Callback to unblank the console (Optional) 312 * @setup: Callback for initializing the console (Optional) 313 * @exit: Callback for teardown of the console (Optional) 314 * @match: Callback for matching a console (Optional) 315 * @flags: Console flags. See enum cons_flags 316 * @index: Console index, e.g. port number 317 * @cflag: TTY control mode flags 318 * @ispeed: TTY input speed 319 * @ospeed: TTY output speed 320 * @seq: Sequence number of the next ringbuffer record to print 321 * @dropped: Number of unreported dropped ringbuffer records 322 * @data: Driver private data 323 * @node: hlist node for the console list 324 * 325 * @nbcon_state: State for nbcon consoles 326 * @nbcon_seq: Sequence number of the next record for nbcon to print 327 * @nbcon_device_ctxt: Context available for non-printing operations 328 * @nbcon_prev_seq: Seq num the previous nbcon owner was assigned to print 329 * @pbufs: Pointer to nbcon private buffer 330 * @kthread: Printer kthread for this console 331 * @rcuwait: RCU-safe wait object for @kthread waking 332 * @irq_work: Defer @kthread waking to IRQ work context 333 */ 334 struct console { 335 char name[16]; 336 void (*write)(struct console *co, const char *s, unsigned int count); 337 int (*read)(struct console *co, char *s, unsigned int count); 338 struct tty_driver *(*device)(struct console *co, int *index); 339 void (*unblank)(void); 340 int (*setup)(struct console *co, char *options); 341 int (*exit)(struct console *co); 342 int (*match)(struct console *co, char *name, int idx, char *options); 343 short flags; 344 short index; 345 int cflag; 346 uint ispeed; 347 uint ospeed; 348 u64 seq; 349 unsigned long dropped; 350 void *data; 351 struct hlist_node node; 352 353 /* nbcon console specific members */ 354 355 /** 356 * @write_atomic: 357 * 358 * NBCON callback to write out text in any context. (Optional) 359 * 360 * This callback is called with the console already acquired. However, 361 * a higher priority context is allowed to take it over by default. 362 * 363 * The callback must call nbcon_enter_unsafe() and nbcon_exit_unsafe() 364 * around any code where the takeover is not safe, for example, when 365 * manipulating the serial port registers. 366 * 367 * nbcon_enter_unsafe() will fail if the context has lost the console 368 * ownership in the meantime. In this case, the callback is no longer 369 * allowed to go forward. It must back out immediately and carefully. 370 * The buffer content is also no longer trusted since it no longer 371 * belongs to the context. 372 * 373 * The callback should allow the takeover whenever it is safe. It 374 * increases the chance to see messages when the system is in trouble. 375 * If the driver must reacquire ownership in order to finalize or 376 * revert hardware changes, nbcon_reacquire_nobuf() can be used. 377 * However, on reacquire the buffer content is no longer available. A 378 * reacquire cannot be used to resume printing. 379 * 380 * The callback can be called from any context (including NMI). 381 * Therefore it must avoid usage of any locking and instead rely 382 * on the console ownership for synchronization. 383 */ 384 void (*write_atomic)(struct console *con, struct nbcon_write_context *wctxt); 385 386 /** 387 * @write_thread: 388 * 389 * NBCON callback to write out text in task context. 390 * 391 * This callback must be called only in task context with both 392 * device_lock() and the nbcon console acquired with 393 * NBCON_PRIO_NORMAL. 394 * 395 * The same rules for console ownership verification and unsafe 396 * sections handling applies as with write_atomic(). 397 * 398 * The console ownership handling is necessary for synchronization 399 * against write_atomic() which is synchronized only via the context. 400 * 401 * The device_lock() provides the primary serialization for operations 402 * on the device. It might be as relaxed (mutex)[*] or as tight 403 * (disabled preemption and interrupts) as needed. It allows 404 * the kthread to operate in the least restrictive mode[**]. 405 * 406 * [*] Standalone nbcon_context_try_acquire() is not safe with 407 * the preemption enabled, see nbcon_owner_matches(). But it 408 * can be safe when always called in the preemptive context 409 * under the device_lock(). 410 * 411 * [**] The device_lock() makes sure that nbcon_context_try_acquire() 412 * would never need to spin which is important especially with 413 * PREEMPT_RT. 414 */ 415 void (*write_thread)(struct console *con, struct nbcon_write_context *wctxt); 416 417 /** 418 * @device_lock: 419 * 420 * NBCON callback to begin synchronization with driver code. 421 * 422 * Console drivers typically must deal with access to the hardware 423 * via user input/output (such as an interactive login shell) and 424 * output of kernel messages via printk() calls. This callback is 425 * called by the printk-subsystem whenever it needs to synchronize 426 * with hardware access by the driver. It should be implemented to 427 * use whatever synchronization mechanism the driver is using for 428 * itself (for example, the port lock for uart serial consoles). 429 * 430 * The callback is always called from task context. It may use any 431 * synchronization method required by the driver. 432 * 433 * IMPORTANT: The callback MUST disable migration. The console driver 434 * may be using a synchronization mechanism that already takes 435 * care of this (such as spinlocks). Otherwise this function must 436 * explicitly call migrate_disable(). 437 * 438 * The flags argument is provided as a convenience to the driver. It 439 * will be passed again to device_unlock(). It can be ignored if the 440 * driver does not need it. 441 */ 442 void (*device_lock)(struct console *con, unsigned long *flags); 443 444 /** 445 * @device_unlock: 446 * 447 * NBCON callback to finish synchronization with driver code. 448 * 449 * It is the counterpart to device_lock(). 450 * 451 * This callback is always called from task context. It must 452 * appropriately re-enable migration (depending on how device_lock() 453 * disabled migration). 454 * 455 * The flags argument is the value of the same variable that was 456 * passed to device_lock(). 457 */ 458 void (*device_unlock)(struct console *con, unsigned long flags); 459 460 atomic_t __private nbcon_state; 461 atomic_long_t __private nbcon_seq; 462 struct nbcon_context __private nbcon_device_ctxt; 463 atomic_long_t __private nbcon_prev_seq; 464 465 struct printk_buffers *pbufs; 466 struct task_struct *kthread; 467 struct rcuwait rcuwait; 468 struct irq_work irq_work; 469 }; 470 471 #ifdef CONFIG_LOCKDEP 472 extern void lockdep_assert_console_list_lock_held(void); 473 #else 474 static inline void lockdep_assert_console_list_lock_held(void) 475 { 476 } 477 #endif 478 479 #ifdef CONFIG_DEBUG_LOCK_ALLOC 480 extern bool console_srcu_read_lock_is_held(void); 481 #else 482 static inline bool console_srcu_read_lock_is_held(void) 483 { 484 return 1; 485 } 486 #endif 487 488 extern int console_srcu_read_lock(void); 489 extern void console_srcu_read_unlock(int cookie); 490 491 extern void console_list_lock(void) __acquires(console_mutex); 492 extern void console_list_unlock(void) __releases(console_mutex); 493 494 extern struct hlist_head console_list; 495 496 /** 497 * console_srcu_read_flags - Locklessly read flags of a possibly registered 498 * console 499 * @con: struct console pointer of console to read flags from 500 * 501 * Locklessly reading @con->flags provides a consistent read value because 502 * there is at most one CPU modifying @con->flags and that CPU is using only 503 * read-modify-write operations to do so. 504 * 505 * Requires console_srcu_read_lock to be held, which implies that @con might 506 * be a registered console. The purpose of holding console_srcu_read_lock is 507 * to guarantee that the console state is valid (CON_SUSPENDED/CON_ENABLED) 508 * and that no exit/cleanup routines will run if the console is currently 509 * undergoing unregistration. 510 * 511 * If the caller is holding the console_list_lock or it is _certain_ that 512 * @con is not and will not become registered, the caller may read 513 * @con->flags directly instead. 514 * 515 * Context: Any context. 516 * Return: The current value of the @con->flags field. 517 */ 518 static inline short console_srcu_read_flags(const struct console *con) 519 { 520 WARN_ON_ONCE(!console_srcu_read_lock_is_held()); 521 522 /* 523 * The READ_ONCE() matches the WRITE_ONCE() when @flags are modified 524 * for registered consoles with console_srcu_write_flags(). 525 */ 526 return data_race(READ_ONCE(con->flags)); 527 } 528 529 /** 530 * console_srcu_write_flags - Write flags for a registered console 531 * @con: struct console pointer of console to write flags to 532 * @flags: new flags value to write 533 * 534 * Only use this function to write flags for registered consoles. It 535 * requires holding the console_list_lock. 536 * 537 * Context: Any context. 538 */ 539 static inline void console_srcu_write_flags(struct console *con, short flags) 540 { 541 lockdep_assert_console_list_lock_held(); 542 543 /* This matches the READ_ONCE() in console_srcu_read_flags(). */ 544 WRITE_ONCE(con->flags, flags); 545 } 546 547 /* Variant of console_is_registered() when the console_list_lock is held. */ 548 static inline bool console_is_registered_locked(const struct console *con) 549 { 550 lockdep_assert_console_list_lock_held(); 551 return !hlist_unhashed(&con->node); 552 } 553 554 /* 555 * console_is_registered - Check if the console is registered 556 * @con: struct console pointer of console to check 557 * 558 * Context: Process context. May sleep while acquiring console list lock. 559 * Return: true if the console is in the console list, otherwise false. 560 * 561 * If false is returned for a console that was previously registered, it 562 * can be assumed that the console's unregistration is fully completed, 563 * including the exit() callback after console list removal. 564 */ 565 static inline bool console_is_registered(const struct console *con) 566 { 567 bool ret; 568 569 console_list_lock(); 570 ret = console_is_registered_locked(con); 571 console_list_unlock(); 572 return ret; 573 } 574 575 /** 576 * for_each_console_srcu() - Iterator over registered consoles 577 * @con: struct console pointer used as loop cursor 578 * 579 * Although SRCU guarantees the console list will be consistent, the 580 * struct console fields may be updated by other CPUs while iterating. 581 * 582 * Requires console_srcu_read_lock to be held. Can be invoked from 583 * any context. 584 */ 585 #define for_each_console_srcu(con) \ 586 hlist_for_each_entry_srcu(con, &console_list, node, \ 587 console_srcu_read_lock_is_held()) 588 589 /** 590 * for_each_console() - Iterator over registered consoles 591 * @con: struct console pointer used as loop cursor 592 * 593 * The console list and the &console.flags are immutable while iterating. 594 * 595 * Requires console_list_lock to be held. 596 */ 597 #define for_each_console(con) \ 598 lockdep_assert_console_list_lock_held(); \ 599 hlist_for_each_entry(con, &console_list, node) 600 601 #ifdef CONFIG_PRINTK 602 extern void nbcon_cpu_emergency_enter(void); 603 extern void nbcon_cpu_emergency_exit(void); 604 extern bool nbcon_can_proceed(struct nbcon_write_context *wctxt); 605 extern bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt); 606 extern bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt); 607 extern void nbcon_reacquire_nobuf(struct nbcon_write_context *wctxt); 608 #else 609 static inline void nbcon_cpu_emergency_enter(void) { } 610 static inline void nbcon_cpu_emergency_exit(void) { } 611 static inline bool nbcon_can_proceed(struct nbcon_write_context *wctxt) { return false; } 612 static inline bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt) { return false; } 613 static inline bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt) { return false; } 614 static inline void nbcon_reacquire_nobuf(struct nbcon_write_context *wctxt) { } 615 #endif 616 617 extern int console_set_on_cmdline; 618 extern struct console *early_console; 619 620 enum con_flush_mode { 621 CONSOLE_FLUSH_PENDING, 622 CONSOLE_REPLAY_ALL, 623 }; 624 625 extern int add_preferred_console(const char *name, const short idx, char *options); 626 extern void console_force_preferred_locked(struct console *con); 627 extern void register_console(struct console *); 628 extern int unregister_console(struct console *); 629 extern void console_lock(void); 630 extern int console_trylock(void); 631 extern void console_unlock(void); 632 extern void console_conditional_schedule(void); 633 extern void console_unblank(void); 634 extern void console_flush_on_panic(enum con_flush_mode mode); 635 extern struct tty_driver *console_device(int *); 636 extern void console_stop(struct console *); 637 extern void console_start(struct console *); 638 extern int is_console_locked(void); 639 extern int braille_register_console(struct console *, int index, 640 char *console_options, char *braille_options); 641 extern int braille_unregister_console(struct console *); 642 #ifdef CONFIG_TTY 643 extern void console_sysfs_notify(void); 644 #else 645 static inline void console_sysfs_notify(void) 646 { } 647 #endif 648 extern bool console_suspend_enabled; 649 650 /* Suspend and resume console messages over PM events */ 651 extern void suspend_console(void); 652 extern void resume_console(void); 653 654 int mda_console_init(void); 655 656 void vcs_make_sysfs(int index); 657 void vcs_remove_sysfs(int index); 658 659 /* Some debug stub to catch some of the obvious races in the VT code */ 660 #define WARN_CONSOLE_UNLOCKED() \ 661 WARN_ON(!atomic_read(&ignore_console_lock_warning) && \ 662 !is_console_locked() && !oops_in_progress) 663 /* 664 * Increment ignore_console_lock_warning if you need to quiet 665 * WARN_CONSOLE_UNLOCKED() for debugging purposes. 666 */ 667 extern atomic_t ignore_console_lock_warning; 668 669 extern void console_init(void); 670 671 /* For deferred console takeover */ 672 void dummycon_register_output_notifier(struct notifier_block *nb); 673 void dummycon_unregister_output_notifier(struct notifier_block *nb); 674 675 #endif /* _LINUX_CONSOLE_H */ 676