2  *  linux/include/linux/console.h
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
46  * @con_deinit: deinitialize the console from @vc.
54  *		Invoked by csi_M and printing to the console.
55  * @con_switch: notifier about the console switch; it is supposed to return
57  * @con_blank:  blank/unblank the console. The target mode is passed in @blank.
60  * @con_font_set: set console @vc font to @font with height @vpitch. @flags can
66  * @con_resize:	resize the @vc console to @width x @height. @from_user is true
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.
81  * @con_debug_enter: prepare the console for the debugger. This includes, but
82  *		is not limited to, unblanking the console, loading an
85  * @con_debug_leave: restore the console to its pre-debug state as closely as
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  */
155  * The interface for a console, or any other device that wants to capture
156  * console messages (printer driver?)
160  * enum cons_flags - General console flags
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
169  * @CON_BOOT:		Marks the console driver as early console driver which
172  *			when the real console driver is registered unless
175  *			that the legacy @console::write callback can be invoked
182  * @CON_EXTENDED:	The console supports the extended output format of
184  * @CON_SUSPENDED:	Indicates if a console is suspended. If true, the
186  * @CON_NBCON:		Console can operate outside of the legacy style console_lock
202  * struct nbcon_state - console state for nbcon consoles
207  * @unsafe:		Console is busy in a non takeover region
209  *			past. The console cannot be safe until re-initialized.
213  * state variable @console::nbcon_state.
234  * are stored in the @console::nbcon_state variable. Ensure this struct stays
241  * enum nbcon_prio - console owner priority for nbcon consoles
248  * A higher priority context can takeover the console when it is
260 struct console;
264  * struct nbcon_context - Context for console acquire/release
265  * @console:			The associated console
270  *				might cause a system freeze when the console
278 	struct console		*console;  member
293  * @ctxt:		The core console context
306  * struct console - The console descriptor structure
307  * @name:		The name of the console driver
309  * @read:		Read callback for console input (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
323  * @node:		hlist node for the console list
330  * @kthread:		Printer kthread for this console
334 struct console {  struct
336 	void			(*write)(struct console *co, const char *s, unsigned int count);  argument
337 	int			(*read)(struct console *co, char *s, unsigned int count);  argument
338 	struct tty_driver	*(*device)(struct console *co, int *index);  argument
340 	int			(*setup)(struct console *co, char *options);  argument
341 	int			(*exit)(struct console *co);  argument
342 	int			(*match)(struct console *co, char *name, int idx, char *options);  argument
353 	/* nbcon console specific members */  argument
360 	 * This callback is called with the console already acquired. However,
367 	 * nbcon_enter_unsafe() will fail if the context has lost the console
382 	 * on the console ownership for synchronization.
384 	void (*write_atomic)(struct console *con, struct nbcon_write_context *wctxt);  argument
392 	 * device_lock() and the nbcon console acquired with
395 	 * The same rules for console ownership verification and unsafe
398 	 * The console ownership handling is necessary for synchronization
415 	void (*write_thread)(struct console *con, struct nbcon_write_context *wctxt);  argument
422 	 * Console drivers typically must deal with access to the hardware
433 	 * IMPORTANT: The callback MUST disable migration. The console driver
442 	void (*device_lock)(struct console *con, unsigned long *flags);  argument
458 	void (*device_unlock)(struct console *con, unsigned long flags);  argument
498  *				console
499  * @con:	struct console pointer of console to read flags from
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
518 static inline short console_srcu_read_flags(const struct console *con)  in console_srcu_read_flags()
530  * console_srcu_write_flags - Write flags for a registered console
531  * @con:	struct console pointer of console to write flags to
539 static inline void console_srcu_write_flags(struct console *con, short flags)  in console_srcu_write_flags()
548 static inline bool console_is_registered_locked(const struct console *con)  in console_is_registered_locked()
555  * console_is_registered - Check if the console is registered
556  * @con:	struct console pointer of console to check
558  * Context: Process context. May sleep while acquiring console list lock.
559  * Return: true if the console is in the console list, otherwise false.
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.
565 static inline bool console_is_registered(const struct console *con)  in console_is_registered()
577  * @con:	struct console pointer used as loop cursor
579  * Although SRCU guarantees the console list will be consistent, the
580  * struct console fields may be updated by other CPUs while iterating.
591  * @con:	struct console pointer used as loop cursor
593  * The console list and the &console.flags are immutable while iterating.
618 extern struct console *early_console;
626 extern void console_force_preferred_locked(struct console *con);
627 extern void register_console(struct console *);
628 extern int unregister_console(struct console *);
636 extern void console_stop(struct console *);
637 extern void console_start(struct console *);
639 extern int braille_register_console(struct console *, int index,
641 extern int braille_unregister_console(struct console *);
650 /* Suspend and resume console messages over PM events */
671 /* For deferred console takeover */