Line data Source code
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/rculist.h>
20 : #include <linux/types.h>
21 :
22 : struct vc_data;
23 : struct console_font_op;
24 : struct console_font;
25 : struct module;
26 : struct tty_struct;
27 : struct notifier_block;
28 :
29 : enum con_scroll {
30 : SM_UP,
31 : SM_DOWN,
32 : };
33 :
34 : enum vc_intensity;
35 :
36 : /**
37 : * struct consw - callbacks for consoles
38 : *
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)
45 : */
46 : struct consw {
47 : struct module *owner;
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,
52 : int width);
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,
59 : unsigned int lines);
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,
63 : unsigned int vpitch, unsigned int flags);
64 : int (*con_font_get)(struct vc_data *vc, struct console_font *font,
65 : unsigned int vpitch);
66 : int (*con_font_default)(struct vc_data *vc,
67 : struct console_font *font, char *name);
68 : int (*con_resize)(struct vc_data *vc, unsigned int width,
69 : unsigned int height, unsigned int user);
70 : void (*con_set_palette)(struct vc_data *vc,
71 : const unsigned char *table);
72 : void (*con_scrolldelta)(struct vc_data *vc, int lines);
73 : int (*con_set_origin)(struct vc_data *vc);
74 : void (*con_save_screen)(struct vc_data *vc);
75 : u8 (*con_build_attr)(struct vc_data *vc, u8 color,
76 : enum vc_intensity intensity,
77 : bool blink, bool underline, bool reverse, bool italic);
78 : void (*con_invert_region)(struct vc_data *vc, u16 *p, int count);
79 : u16 *(*con_screen_pos)(const struct vc_data *vc, int offset);
80 : unsigned long (*con_getxy)(struct vc_data *vc, unsigned long position,
81 : int *px, int *py);
82 : /*
83 : * Flush the video console driver's scrollback buffer
84 : */
85 : void (*con_flush_scrollback)(struct vc_data *vc);
86 : /*
87 : * Prepare the console for the debugger. This includes, but is not
88 : * limited to, unblanking the console, loading an appropriate
89 : * palette, and allowing debugger generated output.
90 : */
91 : int (*con_debug_enter)(struct vc_data *vc);
92 : /*
93 : * Restore the console to its pre-debug state as closely as possible.
94 : */
95 : int (*con_debug_leave)(struct vc_data *vc);
96 : };
97 :
98 : extern const struct consw *conswitchp;
99 :
100 : extern const struct consw dummy_con; /* dummy console buffer */
101 : extern const struct consw vga_con; /* VGA text console */
102 : extern const struct consw newport_con; /* SGI Newport console */
103 :
104 : int con_is_bound(const struct consw *csw);
105 : int do_unregister_con_driver(const struct consw *csw);
106 : int do_take_over_console(const struct consw *sw, int first, int last, int deflt);
107 : void give_up_console(const struct consw *sw);
108 : #ifdef CONFIG_HW_CONSOLE
109 : int con_debug_enter(struct vc_data *vc);
110 : int con_debug_leave(void);
111 : #else
112 : static inline int con_debug_enter(struct vc_data *vc)
113 : {
114 : return 0;
115 : }
116 : static inline int con_debug_leave(void)
117 : {
118 : return 0;
119 : }
120 : #endif
121 :
122 : /* cursor */
123 : #define CM_DRAW (1)
124 : #define CM_ERASE (2)
125 : #define CM_MOVE (3)
126 :
127 : /*
128 : * The interface for a console, or any other device that wants to capture
129 : * console messages (printer driver?)
130 : */
131 :
132 : /**
133 : * cons_flags - General console flags
134 : * @CON_PRINTBUFFER: Used by newly registered consoles to avoid duplicate
135 : * output of messages that were already shown by boot
136 : * consoles or read by userspace via syslog() syscall.
137 : * @CON_CONSDEV: Indicates that the console driver is backing
138 : * /dev/console.
139 : * @CON_ENABLED: Indicates if a console is allowed to print records. If
140 : * false, the console also will not advance to later
141 : * records.
142 : * @CON_BOOT: Marks the console driver as early console driver which
143 : * is used during boot before the real driver becomes
144 : * available. It will be automatically unregistered
145 : * when the real console driver is registered unless
146 : * "keep_bootcon" parameter is used.
147 : * @CON_ANYTIME: A misnomed historical flag which tells the core code
148 : * that the legacy @console::write callback can be invoked
149 : * on a CPU which is marked OFFLINE. That is misleading as
150 : * it suggests that there is no contextual limit for
151 : * invoking the callback. The original motivation was
152 : * readiness of the per-CPU areas.
153 : * @CON_BRL: Indicates a braille device which is exempt from
154 : * receiving the printk spam for obvious reasons.
155 : * @CON_EXTENDED: The console supports the extended output format of
156 : * /dev/kmesg which requires a larger output buffer.
157 : */
158 : enum cons_flags {
159 : CON_PRINTBUFFER = BIT(0),
160 : CON_CONSDEV = BIT(1),
161 : CON_ENABLED = BIT(2),
162 : CON_BOOT = BIT(3),
163 : CON_ANYTIME = BIT(4),
164 : CON_BRL = BIT(5),
165 : CON_EXTENDED = BIT(6),
166 : };
167 :
168 : /**
169 : * struct console - The console descriptor structure
170 : * @name: The name of the console driver
171 : * @write: Write callback to output messages (Optional)
172 : * @read: Read callback for console input (Optional)
173 : * @device: The underlying TTY device driver (Optional)
174 : * @unblank: Callback to unblank the console (Optional)
175 : * @setup: Callback for initializing the console (Optional)
176 : * @exit: Callback for teardown of the console (Optional)
177 : * @match: Callback for matching a console (Optional)
178 : * @flags: Console flags. See enum cons_flags
179 : * @index: Console index, e.g. port number
180 : * @cflag: TTY control mode flags
181 : * @ispeed: TTY input speed
182 : * @ospeed: TTY output speed
183 : * @seq: Sequence number of the next ringbuffer record to print
184 : * @dropped: Number of unreported dropped ringbuffer records
185 : * @data: Driver private data
186 : * @node: hlist node for the console list
187 : */
188 : struct console {
189 : char name[16];
190 : void (*write)(struct console *co, const char *s, unsigned int count);
191 : int (*read)(struct console *co, char *s, unsigned int count);
192 : struct tty_driver *(*device)(struct console *co, int *index);
193 : void (*unblank)(void);
194 : int (*setup)(struct console *co, char *options);
195 : int (*exit)(struct console *co);
196 : int (*match)(struct console *co, char *name, int idx, char *options);
197 : short flags;
198 : short index;
199 : int cflag;
200 : uint ispeed;
201 : uint ospeed;
202 : u64 seq;
203 : unsigned long dropped;
204 : void *data;
205 : struct hlist_node node;
206 : };
207 :
208 : #ifdef CONFIG_LOCKDEP
209 : extern void lockdep_assert_console_list_lock_held(void);
210 : #else
211 : static inline void lockdep_assert_console_list_lock_held(void)
212 : {
213 : }
214 : #endif
215 :
216 : #ifdef CONFIG_DEBUG_LOCK_ALLOC
217 : extern bool console_srcu_read_lock_is_held(void);
218 : #else
219 : static inline bool console_srcu_read_lock_is_held(void)
220 : {
221 : return 1;
222 : }
223 : #endif
224 :
225 : extern int console_srcu_read_lock(void);
226 : extern void console_srcu_read_unlock(int cookie);
227 :
228 : extern void console_list_lock(void) __acquires(console_mutex);
229 : extern void console_list_unlock(void) __releases(console_mutex);
230 :
231 : extern struct hlist_head console_list;
232 :
233 : /**
234 : * console_srcu_read_flags - Locklessly read the console flags
235 : * @con: struct console pointer of console to read flags from
236 : *
237 : * This function provides the necessary READ_ONCE() and data_race()
238 : * notation for locklessly reading the console flags. The READ_ONCE()
239 : * in this function matches the WRITE_ONCE() when @flags are modified
240 : * for registered consoles with console_srcu_write_flags().
241 : *
242 : * Only use this function to read console flags when locklessly
243 : * iterating the console list via srcu.
244 : *
245 : * Context: Any context.
246 : */
247 : static inline short console_srcu_read_flags(const struct console *con)
248 : {
249 5612 : WARN_ON_ONCE(!console_srcu_read_lock_is_held());
250 :
251 : /*
252 : * Locklessly reading console->flags provides a consistent
253 : * read value because there is at most one CPU modifying
254 : * console->flags and that CPU is using only read-modify-write
255 : * operations to do so.
256 : */
257 5612 : return data_race(READ_ONCE(con->flags));
258 : }
259 :
260 : /**
261 : * console_srcu_write_flags - Write flags for a registered console
262 : * @con: struct console pointer of console to write flags to
263 : * @flags: new flags value to write
264 : *
265 : * Only use this function to write flags for registered consoles. It
266 : * requires holding the console_list_lock.
267 : *
268 : * Context: Any context.
269 : */
270 : static inline void console_srcu_write_flags(struct console *con, short flags)
271 : {
272 : lockdep_assert_console_list_lock_held();
273 :
274 : /* This matches the READ_ONCE() in console_srcu_read_flags(). */
275 1 : WRITE_ONCE(con->flags, flags);
276 : }
277 :
278 : /* Variant of console_is_registered() when the console_list_lock is held. */
279 : static inline bool console_is_registered_locked(const struct console *con)
280 : {
281 : lockdep_assert_console_list_lock_held();
282 1 : return !hlist_unhashed(&con->node);
283 : }
284 :
285 : /*
286 : * console_is_registered - Check if the console is registered
287 : * @con: struct console pointer of console to check
288 : *
289 : * Context: Process context. May sleep while acquiring console list lock.
290 : * Return: true if the console is in the console list, otherwise false.
291 : *
292 : * If false is returned for a console that was previously registered, it
293 : * can be assumed that the console's unregistration is fully completed,
294 : * including the exit() callback after console list removal.
295 : */
296 : static inline bool console_is_registered(const struct console *con)
297 : {
298 : bool ret;
299 :
300 : console_list_lock();
301 : ret = console_is_registered_locked(con);
302 : console_list_unlock();
303 : return ret;
304 : }
305 :
306 : /**
307 : * for_each_console_srcu() - Iterator over registered consoles
308 : * @con: struct console pointer used as loop cursor
309 : *
310 : * Although SRCU guarantees the console list will be consistent, the
311 : * struct console fields may be updated by other CPUs while iterating.
312 : *
313 : * Requires console_srcu_read_lock to be held. Can be invoked from
314 : * any context.
315 : */
316 : #define for_each_console_srcu(con) \
317 : hlist_for_each_entry_srcu(con, &console_list, node, \
318 : console_srcu_read_lock_is_held())
319 :
320 : /**
321 : * for_each_console() - Iterator over registered consoles
322 : * @con: struct console pointer used as loop cursor
323 : *
324 : * The console list and the console->flags are immutable while iterating.
325 : *
326 : * Requires console_list_lock to be held.
327 : */
328 : #define for_each_console(con) \
329 : lockdep_assert_console_list_lock_held(); \
330 : hlist_for_each_entry(con, &console_list, node)
331 :
332 : extern int console_set_on_cmdline;
333 : extern struct console *early_console;
334 :
335 : enum con_flush_mode {
336 : CONSOLE_FLUSH_PENDING,
337 : CONSOLE_REPLAY_ALL,
338 : };
339 :
340 : extern int add_preferred_console(char *name, int idx, char *options);
341 : extern void console_force_preferred_locked(struct console *con);
342 : extern void register_console(struct console *);
343 : extern int unregister_console(struct console *);
344 : extern void console_lock(void);
345 : extern int console_trylock(void);
346 : extern void console_unlock(void);
347 : extern void console_conditional_schedule(void);
348 : extern void console_unblank(void);
349 : extern void console_flush_on_panic(enum con_flush_mode mode);
350 : extern struct tty_driver *console_device(int *);
351 : extern void console_stop(struct console *);
352 : extern void console_start(struct console *);
353 : extern int is_console_locked(void);
354 : extern int braille_register_console(struct console *, int index,
355 : char *console_options, char *braille_options);
356 : extern int braille_unregister_console(struct console *);
357 : #ifdef CONFIG_TTY
358 : extern void console_sysfs_notify(void);
359 : #else
360 : static inline void console_sysfs_notify(void)
361 : { }
362 : #endif
363 : extern bool console_suspend_enabled;
364 :
365 : /* Suspend and resume console messages over PM events */
366 : extern void suspend_console(void);
367 : extern void resume_console(void);
368 :
369 : int mda_console_init(void);
370 :
371 : void vcs_make_sysfs(int index);
372 : void vcs_remove_sysfs(int index);
373 :
374 : /* Some debug stub to catch some of the obvious races in the VT code */
375 : #define WARN_CONSOLE_UNLOCKED() \
376 : WARN_ON(!atomic_read(&ignore_console_lock_warning) && \
377 : !is_console_locked() && !oops_in_progress)
378 : /*
379 : * Increment ignore_console_lock_warning if you need to quiet
380 : * WARN_CONSOLE_UNLOCKED() for debugging purposes.
381 : */
382 : extern atomic_t ignore_console_lock_warning;
383 :
384 : /* VESA Blanking Levels */
385 : #define VESA_NO_BLANKING 0
386 : #define VESA_VSYNC_SUSPEND 1
387 : #define VESA_HSYNC_SUSPEND 2
388 : #define VESA_POWERDOWN 3
389 :
390 : extern void console_init(void);
391 :
392 : /* For deferred console takeover */
393 : void dummycon_register_output_notifier(struct notifier_block *nb);
394 : void dummycon_unregister_output_notifier(struct notifier_block *nb);
395 :
396 : #endif /* _LINUX_CONSOLE_H */
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