2 * linux/include/linux/console.h
4 * Copyright (C) 1993 Hamish Macdonald
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
11 * 10-Mar-94: Arno Griffioen: Conversion for vt100 emulator port from PC LINUX
14 #ifndef _LINUX_CONSOLE_H_
15 #define _LINUX_CONSOLE_H_ 1
17 #include <linux/atomic.h>
18 #include <linux/bits.h>
19 #include <linux/rculist.h>
20 #include <linux/types.h>
23 struct console_font_op;
27 struct notifier_block;
37 * struct consw - callbacks for consoles
39 * @con_scroll: move lines from @top to @bottom in direction @dir by @lines.
40 * Return true if no generic handling should be done.
41 * Invoked by csi_M and printing to the console.
42 * @con_set_palette: sets the palette of the console to @table (optional)
43 * @con_scrolldelta: the contents of the console should be scrolled by @lines.
44 * Invoked by user. (optional)
48 const char *(*con_startup)(void);
49 void (*con_init)(struct vc_data *vc, int init);
50 void (*con_deinit)(struct vc_data *vc);
51 void (*con_clear)(struct vc_data *vc, int sy, int sx, int height,
53 void (*con_putc)(struct vc_data *vc, int c, int ypos, int xpos);
54 void (*con_putcs)(struct vc_data *vc, const unsigned short *s,
55 int count, int ypos, int xpos);
56 void (*con_cursor)(struct vc_data *vc, int mode);
57 bool (*con_scroll)(struct vc_data *vc, unsigned int top,
58 unsigned int bottom, enum con_scroll dir,
60 int (*con_switch)(struct vc_data *vc);
61 int (*con_blank)(struct vc_data *vc, int blank, int mode_switch);
62 int (*con_font_set)(struct vc_data *vc, struct console_font *font,
64 int (*con_font_get)(struct vc_data *vc, struct console_font *font);
65 int (*con_font_default)(struct vc_data *vc,
66 struct console_font *font, char *name);
67 int (*con_resize)(struct vc_data *vc, unsigned int width,
68 unsigned int height, unsigned int user);
69 void (*con_set_palette)(struct vc_data *vc,
70 const unsigned char *table);
71 void (*con_scrolldelta)(struct vc_data *vc, int lines);
72 int (*con_set_origin)(struct vc_data *vc);
73 void (*con_save_screen)(struct vc_data *vc);
74 u8 (*con_build_attr)(struct vc_data *vc, u8 color,
75 enum vc_intensity intensity,
76 bool blink, bool underline, bool reverse, bool italic);
77 void (*con_invert_region)(struct vc_data *vc, u16 *p, int count);
78 u16 *(*con_screen_pos)(const struct vc_data *vc, int offset);
79 unsigned long (*con_getxy)(struct vc_data *vc, unsigned long position,
82 * Flush the video console driver's scrollback buffer
84 void (*con_flush_scrollback)(struct vc_data *vc);
86 * Prepare the console for the debugger. This includes, but is not
87 * limited to, unblanking the console, loading an appropriate
88 * palette, and allowing debugger generated output.
90 int (*con_debug_enter)(struct vc_data *vc);
92 * Restore the console to its pre-debug state as closely as possible.
94 int (*con_debug_leave)(struct vc_data *vc);
97 extern const struct consw *conswitchp;
99 extern const struct consw dummy_con; /* dummy console buffer */
100 extern const struct consw vga_con; /* VGA text console */
101 extern const struct consw newport_con; /* SGI Newport console */
103 int con_is_bound(const struct consw *csw);
104 int do_unregister_con_driver(const struct consw *csw);
105 int do_take_over_console(const struct consw *sw, int first, int last, int deflt);
106 void give_up_console(const struct consw *sw);
107 #ifdef CONFIG_HW_CONSOLE
108 int con_debug_enter(struct vc_data *vc);
109 int con_debug_leave(void);
111 static inline int con_debug_enter(struct vc_data *vc)
115 static inline int con_debug_leave(void)
127 * The interface for a console, or any other device that wants to capture
128 * console messages (printer driver?)
132 * cons_flags - General console flags
133 * @CON_PRINTBUFFER: Used by newly registered consoles to avoid duplicate
134 * output of messages that were already shown by boot
135 * consoles or read by userspace via syslog() syscall.
136 * @CON_CONSDEV: Indicates that the console driver is backing
138 * @CON_ENABLED: Indicates if a console is allowed to print records. If
139 * false, the console also will not advance to later
141 * @CON_BOOT: Marks the console driver as early console driver which
142 * is used during boot before the real driver becomes
143 * available. It will be automatically unregistered
144 * when the real console driver is registered unless
145 * "keep_bootcon" parameter is used.
146 * @CON_ANYTIME: A misnomed historical flag which tells the core code
147 * that the legacy @console::write callback can be invoked
148 * on a CPU which is marked OFFLINE. That is misleading as
149 * it suggests that there is no contextual limit for
150 * invoking the callback. The original motivation was
151 * readiness of the per-CPU areas.
152 * @CON_BRL: Indicates a braille device which is exempt from
153 * receiving the printk spam for obvious reasons.
154 * @CON_EXTENDED: The console supports the extended output format of
155 * /dev/kmesg which requires a larger output buffer.
158 CON_PRINTBUFFER = BIT(0),
159 CON_CONSDEV = BIT(1),
160 CON_ENABLED = BIT(2),
162 CON_ANYTIME = BIT(4),
164 CON_EXTENDED = BIT(6),
168 * struct console - The console descriptor structure
169 * @name: The name of the console driver
170 * @write: Write callback to output messages (Optional)
171 * @read: Read callback for console input (Optional)
172 * @device: The underlying TTY device driver (Optional)
173 * @unblank: Callback to unblank the console (Optional)
174 * @setup: Callback for initializing the console (Optional)
175 * @exit: Callback for teardown of the console (Optional)
176 * @match: Callback for matching a console (Optional)
177 * @flags: Console flags. See enum cons_flags
178 * @index: Console index, e.g. port number
179 * @cflag: TTY control mode flags
180 * @ispeed: TTY input speed
181 * @ospeed: TTY output speed
182 * @seq: Sequence number of the next ringbuffer record to print
183 * @dropped: Number of unreported dropped ringbuffer records
184 * @data: Driver private data
185 * @node: hlist node for the console list
189 void (*write)(struct console *co, const char *s, unsigned int count);
190 int (*read)(struct console *co, char *s, unsigned int count);
191 struct tty_driver *(*device)(struct console *co, int *index);
192 void (*unblank)(void);
193 int (*setup)(struct console *co, char *options);
194 int (*exit)(struct console *co);
195 int (*match)(struct console *co, char *name, int idx, char *options);
202 unsigned long dropped;
204 struct hlist_node node;
207 #ifdef CONFIG_LOCKDEP
208 extern void lockdep_assert_console_list_lock_held(void);
210 static inline void lockdep_assert_console_list_lock_held(void)
215 #ifdef CONFIG_DEBUG_LOCK_ALLOC
216 extern bool console_srcu_read_lock_is_held(void);
218 static inline bool console_srcu_read_lock_is_held(void)
224 extern int console_srcu_read_lock(void);
225 extern void console_srcu_read_unlock(int cookie);
227 extern void console_list_lock(void) __acquires(console_mutex);
228 extern void console_list_unlock(void) __releases(console_mutex);
230 extern struct hlist_head console_list;
233 * console_srcu_read_flags - Locklessly read the console flags
234 * @con: struct console pointer of console to read flags from
236 * This function provides the necessary READ_ONCE() and data_race()
237 * notation for locklessly reading the console flags. The READ_ONCE()
238 * in this function matches the WRITE_ONCE() when @flags are modified
239 * for registered consoles with console_srcu_write_flags().
241 * Only use this function to read console flags when locklessly
242 * iterating the console list via srcu.
244 * Context: Any context.
246 static inline short console_srcu_read_flags(const struct console *con)
248 WARN_ON_ONCE(!console_srcu_read_lock_is_held());
251 * Locklessly reading console->flags provides a consistent
252 * read value because there is at most one CPU modifying
253 * console->flags and that CPU is using only read-modify-write
254 * operations to do so.
256 return data_race(READ_ONCE(con->flags));
260 * console_srcu_write_flags - Write flags for a registered console
261 * @con: struct console pointer of console to write flags to
262 * @flags: new flags value to write
264 * Only use this function to write flags for registered consoles. It
265 * requires holding the console_list_lock.
267 * Context: Any context.
269 static inline void console_srcu_write_flags(struct console *con, short flags)
271 lockdep_assert_console_list_lock_held();
273 /* This matches the READ_ONCE() in console_srcu_read_flags(). */
274 WRITE_ONCE(con->flags, flags);
277 /* Variant of console_is_registered() when the console_list_lock is held. */
278 static inline bool console_is_registered_locked(const struct console *con)
280 lockdep_assert_console_list_lock_held();
281 return !hlist_unhashed(&con->node);
285 * console_is_registered - Check if the console is registered
286 * @con: struct console pointer of console to check
288 * Context: Process context. May sleep while acquiring console list lock.
289 * Return: true if the console is in the console list, otherwise false.
291 * If false is returned for a console that was previously registered, it
292 * can be assumed that the console's unregistration is fully completed,
293 * including the exit() callback after console list removal.
295 static inline bool console_is_registered(const struct console *con)
300 ret = console_is_registered_locked(con);
301 console_list_unlock();
306 * for_each_console_srcu() - Iterator over registered consoles
307 * @con: struct console pointer used as loop cursor
309 * Although SRCU guarantees the console list will be consistent, the
310 * struct console fields may be updated by other CPUs while iterating.
312 * Requires console_srcu_read_lock to be held. Can be invoked from
315 #define for_each_console_srcu(con) \
316 hlist_for_each_entry_srcu(con, &console_list, node, \
317 console_srcu_read_lock_is_held())
320 * for_each_console() - Iterator over registered consoles
321 * @con: struct console pointer used as loop cursor
323 * The console list and the console->flags are immutable while iterating.
325 * Requires console_list_lock to be held.
327 #define for_each_console(con) \
328 lockdep_assert_console_list_lock_held(); \
329 hlist_for_each_entry(con, &console_list, node)
331 extern int console_set_on_cmdline;
332 extern struct console *early_console;
334 enum con_flush_mode {
335 CONSOLE_FLUSH_PENDING,
339 extern int add_preferred_console(char *name, int idx, char *options);
340 extern void console_force_preferred_locked(struct console *con);
341 extern void register_console(struct console *);
342 extern int unregister_console(struct console *);
343 extern void console_lock(void);
344 extern int console_trylock(void);
345 extern void console_unlock(void);
346 extern void console_conditional_schedule(void);
347 extern void console_unblank(void);
348 extern void console_flush_on_panic(enum con_flush_mode mode);
349 extern struct tty_driver *console_device(int *);
350 extern void console_stop(struct console *);
351 extern void console_start(struct console *);
352 extern int is_console_locked(void);
353 extern int braille_register_console(struct console *, int index,
354 char *console_options, char *braille_options);
355 extern int braille_unregister_console(struct console *);
357 extern void console_sysfs_notify(void);
359 static inline void console_sysfs_notify(void)
362 extern bool console_suspend_enabled;
364 /* Suspend and resume console messages over PM events */
365 extern void suspend_console(void);
366 extern void resume_console(void);
368 int mda_console_init(void);
370 void vcs_make_sysfs(int index);
371 void vcs_remove_sysfs(int index);
373 /* Some debug stub to catch some of the obvious races in the VT code */
374 #define WARN_CONSOLE_UNLOCKED() \
375 WARN_ON(!atomic_read(&ignore_console_lock_warning) && \
376 !is_console_locked() && !oops_in_progress)
378 * Increment ignore_console_lock_warning if you need to quiet
379 * WARN_CONSOLE_UNLOCKED() for debugging purposes.
381 extern atomic_t ignore_console_lock_warning;
383 /* VESA Blanking Levels */
384 #define VESA_NO_BLANKING 0
385 #define VESA_VSYNC_SUSPEND 1
386 #define VESA_HSYNC_SUSPEND 2
387 #define VESA_POWERDOWN 3
389 extern void console_init(void);
391 /* For deferred console takeover */
392 void dummycon_register_output_notifier(struct notifier_block *nb);
393 void dummycon_unregister_output_notifier(struct notifier_block *nb);
395 #endif /* _LINUX_CONSOLE_H */