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_init: initialize the console on @vc. @init is true for the very first
40 * call on this @vc.
41 * @con_clear: erase @count characters at [@x, @y] on @vc. @count >= 1.
42 * @con_scroll: move lines from @top to @bottom in direction @dir by @lines.
43 * Return true if no generic handling should be done.
44 * Invoked by csi_M and printing to the console.
45 * @con_switch: notifier about the console switch; it is supposed to return
46 * true if a redraw is needed.
47 * @con_set_palette: sets the palette of the console to @table (optional)
48 * @con_scrolldelta: the contents of the console should be scrolled by @lines.
49 * Invoked by user. (optional)
50 */
51 struct consw {
52 struct module *owner;
53 const char *(*con_startup)(void);
54 void (*con_init)(struct vc_data *vc, bool init);
55 void (*con_deinit)(struct vc_data *vc);
56 void (*con_clear)(struct vc_data *vc, unsigned int y,
57 unsigned int x, unsigned int count);
58 void (*con_putc)(struct vc_data *vc, int c, int ypos, int xpos);
59 void (*con_putcs)(struct vc_data *vc, const unsigned short *s,
60 int count, int ypos, int xpos);
61 void (*con_cursor)(struct vc_data *vc, int mode);
62 bool (*con_scroll)(struct vc_data *vc, unsigned int top,
63 unsigned int bottom, enum con_scroll dir,
64 unsigned int lines);
65 bool (*con_switch)(struct vc_data *vc);
66 int (*con_blank)(struct vc_data *vc, int blank, int mode_switch);
67 int (*con_font_set)(struct vc_data *vc, struct console_font *font,
68 unsigned int vpitch, unsigned int flags);
69 int (*con_font_get)(struct vc_data *vc, struct console_font *font,
70 unsigned int vpitch);
71 int (*con_font_default)(struct vc_data *vc,
72 struct console_font *font, char *name);
73 int (*con_resize)(struct vc_data *vc, unsigned int width,
74 unsigned int height, unsigned int user);
75 void (*con_set_palette)(struct vc_data *vc,
76 const unsigned char *table);
77 void (*con_scrolldelta)(struct vc_data *vc, int lines);
78 int (*con_set_origin)(struct vc_data *vc);
79 void (*con_save_screen)(struct vc_data *vc);
80 u8 (*con_build_attr)(struct vc_data *vc, u8 color,
81 enum vc_intensity intensity,
82 bool blink, bool underline, bool reverse, bool italic);
83 void (*con_invert_region)(struct vc_data *vc, u16 *p, int count);
84 u16 *(*con_screen_pos)(const struct vc_data *vc, int offset);
85 unsigned long (*con_getxy)(struct vc_data *vc, unsigned long position,
86 int *px, int *py);
87 /*
88 * Flush the video console driver's scrollback buffer
89 */
90 void (*con_flush_scrollback)(struct vc_data *vc);
91 /*
92 * Prepare the console for the debugger. This includes, but is not
93 * limited to, unblanking the console, loading an appropriate
94 * palette, and allowing debugger generated output.
95 */
96 int (*con_debug_enter)(struct vc_data *vc);
97 /*
98 * Restore the console to its pre-debug state as closely as possible.
99 */
100 int (*con_debug_leave)(struct vc_data *vc);
101 };
102
103 extern const struct consw *conswitchp;
104
105 extern const struct consw dummy_con; /* dummy console buffer */
106 extern const struct consw vga_con; /* VGA text console */
107 extern const struct consw newport_con; /* SGI Newport console */
108
109 int con_is_bound(const struct consw *csw);
110 int do_unregister_con_driver(const struct consw *csw);
111 int do_take_over_console(const struct consw *sw, int first, int last, int deflt);
112 void give_up_console(const struct consw *sw);
113 #ifdef CONFIG_HW_CONSOLE
114 int con_debug_enter(struct vc_data *vc);
115 int con_debug_leave(void);
116 #else
con_debug_enter(struct vc_data * vc)117 static inline int con_debug_enter(struct vc_data *vc)
118 {
119 return 0;
120 }
con_debug_leave(void)121 static inline int con_debug_leave(void)
122 {
123 return 0;
124 }
125 #endif
126
127 /* cursor */
128 #define CM_DRAW (1)
129 #define CM_ERASE (2)
130 #define CM_MOVE (3)
131
132 /*
133 * The interface for a console, or any other device that wants to capture
134 * console messages (printer driver?)
135 */
136
137 /**
138 * cons_flags - General console flags
139 * @CON_PRINTBUFFER: Used by newly registered consoles to avoid duplicate
140 * output of messages that were already shown by boot
141 * consoles or read by userspace via syslog() syscall.
142 * @CON_CONSDEV: Indicates that the console driver is backing
143 * /dev/console.
144 * @CON_ENABLED: Indicates if a console is allowed to print records. If
145 * false, the console also will not advance to later
146 * records.
147 * @CON_BOOT: Marks the console driver as early console driver which
148 * is used during boot before the real driver becomes
149 * available. It will be automatically unregistered
150 * when the real console driver is registered unless
151 * "keep_bootcon" parameter is used.
152 * @CON_ANYTIME: A misnomed historical flag which tells the core code
153 * that the legacy @console::write callback can be invoked
154 * on a CPU which is marked OFFLINE. That is misleading as
155 * it suggests that there is no contextual limit for
156 * invoking the callback. The original motivation was
157 * readiness of the per-CPU areas.
158 * @CON_BRL: Indicates a braille device which is exempt from
159 * receiving the printk spam for obvious reasons.
160 * @CON_EXTENDED: The console supports the extended output format of
161 * /dev/kmesg which requires a larger output buffer.
162 * @CON_SUSPENDED: Indicates if a console is suspended. If true, the
163 * printing callbacks must not be called.
164 */
165 enum cons_flags {
166 CON_PRINTBUFFER = BIT(0),
167 CON_CONSDEV = BIT(1),
168 CON_ENABLED = BIT(2),
169 CON_BOOT = BIT(3),
170 CON_ANYTIME = BIT(4),
171 CON_BRL = BIT(5),
172 CON_EXTENDED = BIT(6),
173 CON_SUSPENDED = BIT(7),
174 };
175
176 /**
177 * struct console - The console descriptor structure
178 * @name: The name of the console driver
179 * @write: Write callback to output messages (Optional)
180 * @read: Read callback for console input (Optional)
181 * @device: The underlying TTY device driver (Optional)
182 * @unblank: Callback to unblank the console (Optional)
183 * @setup: Callback for initializing the console (Optional)
184 * @exit: Callback for teardown of the console (Optional)
185 * @match: Callback for matching a console (Optional)
186 * @flags: Console flags. See enum cons_flags
187 * @index: Console index, e.g. port number
188 * @cflag: TTY control mode flags
189 * @ispeed: TTY input speed
190 * @ospeed: TTY output speed
191 * @seq: Sequence number of the next ringbuffer record to print
192 * @dropped: Number of unreported dropped ringbuffer records
193 * @data: Driver private data
194 * @node: hlist node for the console list
195 */
196 struct console {
197 char name[16];
198 void (*write)(struct console *co, const char *s, unsigned int count);
199 int (*read)(struct console *co, char *s, unsigned int count);
200 struct tty_driver *(*device)(struct console *co, int *index);
201 void (*unblank)(void);
202 int (*setup)(struct console *co, char *options);
203 int (*exit)(struct console *co);
204 int (*match)(struct console *co, char *name, int idx, char *options);
205 short flags;
206 short index;
207 int cflag;
208 uint ispeed;
209 uint ospeed;
210 u64 seq;
211 unsigned long dropped;
212 void *data;
213 struct hlist_node node;
214 };
215
216 #ifdef CONFIG_LOCKDEP
217 extern void lockdep_assert_console_list_lock_held(void);
218 #else
lockdep_assert_console_list_lock_held(void)219 static inline void lockdep_assert_console_list_lock_held(void)
220 {
221 }
222 #endif
223
224 #ifdef CONFIG_DEBUG_LOCK_ALLOC
225 extern bool console_srcu_read_lock_is_held(void);
226 #else
console_srcu_read_lock_is_held(void)227 static inline bool console_srcu_read_lock_is_held(void)
228 {
229 return 1;
230 }
231 #endif
232
233 extern int console_srcu_read_lock(void);
234 extern void console_srcu_read_unlock(int cookie);
235
236 extern void console_list_lock(void) __acquires(console_mutex);
237 extern void console_list_unlock(void) __releases(console_mutex);
238
239 extern struct hlist_head console_list;
240
241 /**
242 * console_srcu_read_flags - Locklessly read the console flags
243 * @con: struct console pointer of console to read flags from
244 *
245 * This function provides the necessary READ_ONCE() and data_race()
246 * notation for locklessly reading the console flags. The READ_ONCE()
247 * in this function matches the WRITE_ONCE() when @flags are modified
248 * for registered consoles with console_srcu_write_flags().
249 *
250 * Only use this function to read console flags when locklessly
251 * iterating the console list via srcu.
252 *
253 * Context: Any context.
254 */
console_srcu_read_flags(const struct console * con)255 static inline short console_srcu_read_flags(const struct console *con)
256 {
257 WARN_ON_ONCE(!console_srcu_read_lock_is_held());
258
259 /*
260 * Locklessly reading console->flags provides a consistent
261 * read value because there is at most one CPU modifying
262 * console->flags and that CPU is using only read-modify-write
263 * operations to do so.
264 */
265 return data_race(READ_ONCE(con->flags));
266 }
267
268 /**
269 * console_srcu_write_flags - Write flags for a registered console
270 * @con: struct console pointer of console to write flags to
271 * @flags: new flags value to write
272 *
273 * Only use this function to write flags for registered consoles. It
274 * requires holding the console_list_lock.
275 *
276 * Context: Any context.
277 */
console_srcu_write_flags(struct console * con,short flags)278 static inline void console_srcu_write_flags(struct console *con, short flags)
279 {
280 lockdep_assert_console_list_lock_held();
281
282 /* This matches the READ_ONCE() in console_srcu_read_flags(). */
283 WRITE_ONCE(con->flags, flags);
284 }
285
286 /* Variant of console_is_registered() when the console_list_lock is held. */
console_is_registered_locked(const struct console * con)287 static inline bool console_is_registered_locked(const struct console *con)
288 {
289 lockdep_assert_console_list_lock_held();
290 return !hlist_unhashed(&con->node);
291 }
292
293 /*
294 * console_is_registered - Check if the console is registered
295 * @con: struct console pointer of console to check
296 *
297 * Context: Process context. May sleep while acquiring console list lock.
298 * Return: true if the console is in the console list, otherwise false.
299 *
300 * If false is returned for a console that was previously registered, it
301 * can be assumed that the console's unregistration is fully completed,
302 * including the exit() callback after console list removal.
303 */
console_is_registered(const struct console * con)304 static inline bool console_is_registered(const struct console *con)
305 {
306 bool ret;
307
308 console_list_lock();
309 ret = console_is_registered_locked(con);
310 console_list_unlock();
311 return ret;
312 }
313
314 /**
315 * for_each_console_srcu() - Iterator over registered consoles
316 * @con: struct console pointer used as loop cursor
317 *
318 * Although SRCU guarantees the console list will be consistent, the
319 * struct console fields may be updated by other CPUs while iterating.
320 *
321 * Requires console_srcu_read_lock to be held. Can be invoked from
322 * any context.
323 */
324 #define for_each_console_srcu(con) \
325 hlist_for_each_entry_srcu(con, &console_list, node, \
326 console_srcu_read_lock_is_held())
327
328 /**
329 * for_each_console() - Iterator over registered consoles
330 * @con: struct console pointer used as loop cursor
331 *
332 * The console list and the console->flags are immutable while iterating.
333 *
334 * Requires console_list_lock to be held.
335 */
336 #define for_each_console(con) \
337 lockdep_assert_console_list_lock_held(); \
338 hlist_for_each_entry(con, &console_list, node)
339
340 extern int console_set_on_cmdline;
341 extern struct console *early_console;
342
343 enum con_flush_mode {
344 CONSOLE_FLUSH_PENDING,
345 CONSOLE_REPLAY_ALL,
346 };
347
348 extern int add_preferred_console(char *name, int idx, char *options);
349 extern void console_force_preferred_locked(struct console *con);
350 extern void register_console(struct console *);
351 extern int unregister_console(struct console *);
352 extern void console_lock(void);
353 extern int console_trylock(void);
354 extern void console_unlock(void);
355 extern void console_conditional_schedule(void);
356 extern void console_unblank(void);
357 extern void console_flush_on_panic(enum con_flush_mode mode);
358 extern struct tty_driver *console_device(int *);
359 extern void console_stop(struct console *);
360 extern void console_start(struct console *);
361 extern int is_console_locked(void);
362 extern int braille_register_console(struct console *, int index,
363 char *console_options, char *braille_options);
364 extern int braille_unregister_console(struct console *);
365 #ifdef CONFIG_TTY
366 extern void console_sysfs_notify(void);
367 #else
console_sysfs_notify(void)368 static inline void console_sysfs_notify(void)
369 { }
370 #endif
371 extern bool console_suspend_enabled;
372
373 /* Suspend and resume console messages over PM events */
374 extern void suspend_console(void);
375 extern void resume_console(void);
376
377 int mda_console_init(void);
378
379 void vcs_make_sysfs(int index);
380 void vcs_remove_sysfs(int index);
381
382 /* Some debug stub to catch some of the obvious races in the VT code */
383 #define WARN_CONSOLE_UNLOCKED() \
384 WARN_ON(!atomic_read(&ignore_console_lock_warning) && \
385 !is_console_locked() && !oops_in_progress)
386 /*
387 * Increment ignore_console_lock_warning if you need to quiet
388 * WARN_CONSOLE_UNLOCKED() for debugging purposes.
389 */
390 extern atomic_t ignore_console_lock_warning;
391
392 /* VESA Blanking Levels */
393 #define VESA_NO_BLANKING 0
394 #define VESA_VSYNC_SUSPEND 1
395 #define VESA_HSYNC_SUSPEND 2
396 #define VESA_POWERDOWN 3
397
398 extern void console_init(void);
399
400 /* For deferred console takeover */
401 void dummycon_register_output_notifier(struct notifier_block *nb);
402 void dummycon_unregister_output_notifier(struct notifier_block *nb);
403
404 #endif /* _LINUX_CONSOLE_H */
405