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
con_debug_enter(struct vc_data * vc)112 static inline int con_debug_enter(struct vc_data *vc)
113 {
114 return 0;
115 }
con_debug_leave(void)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 * @CON_SUSPENDED: Indicates if a console is suspended. If true, the
158 * printing callbacks must not be called.
159 */
160 enum cons_flags {
161 CON_PRINTBUFFER = BIT(0),
162 CON_CONSDEV = BIT(1),
163 CON_ENABLED = BIT(2),
164 CON_BOOT = BIT(3),
165 CON_ANYTIME = BIT(4),
166 CON_BRL = BIT(5),
167 CON_EXTENDED = BIT(6),
168 CON_SUSPENDED = BIT(7),
169 };
170
171 /**
172 * struct console - The console descriptor structure
173 * @name: The name of the console driver
174 * @write: Write callback to output messages (Optional)
175 * @read: Read callback for console input (Optional)
176 * @device: The underlying TTY device driver (Optional)
177 * @unblank: Callback to unblank the console (Optional)
178 * @setup: Callback for initializing the console (Optional)
179 * @exit: Callback for teardown of the console (Optional)
180 * @match: Callback for matching a console (Optional)
181 * @flags: Console flags. See enum cons_flags
182 * @index: Console index, e.g. port number
183 * @cflag: TTY control mode flags
184 * @ispeed: TTY input speed
185 * @ospeed: TTY output speed
186 * @seq: Sequence number of the next ringbuffer record to print
187 * @dropped: Number of unreported dropped ringbuffer records
188 * @data: Driver private data
189 * @node: hlist node for the console list
190 */
191 struct console {
192 char name[16];
193 void (*write)(struct console *co, const char *s, unsigned int count);
194 int (*read)(struct console *co, char *s, unsigned int count);
195 struct tty_driver *(*device)(struct console *co, int *index);
196 void (*unblank)(void);
197 int (*setup)(struct console *co, char *options);
198 int (*exit)(struct console *co);
199 int (*match)(struct console *co, char *name, int idx, char *options);
200 short flags;
201 short index;
202 int cflag;
203 uint ispeed;
204 uint ospeed;
205 u64 seq;
206 unsigned long dropped;
207 void *data;
208 struct hlist_node node;
209 };
210
211 #ifdef CONFIG_LOCKDEP
212 extern void lockdep_assert_console_list_lock_held(void);
213 #else
lockdep_assert_console_list_lock_held(void)214 static inline void lockdep_assert_console_list_lock_held(void)
215 {
216 }
217 #endif
218
219 #ifdef CONFIG_DEBUG_LOCK_ALLOC
220 extern bool console_srcu_read_lock_is_held(void);
221 #else
console_srcu_read_lock_is_held(void)222 static inline bool console_srcu_read_lock_is_held(void)
223 {
224 return 1;
225 }
226 #endif
227
228 extern int console_srcu_read_lock(void);
229 extern void console_srcu_read_unlock(int cookie);
230
231 extern void console_list_lock(void) __acquires(console_mutex);
232 extern void console_list_unlock(void) __releases(console_mutex);
233
234 extern struct hlist_head console_list;
235
236 /**
237 * console_srcu_read_flags - Locklessly read the console flags
238 * @con: struct console pointer of console to read flags from
239 *
240 * This function provides the necessary READ_ONCE() and data_race()
241 * notation for locklessly reading the console flags. The READ_ONCE()
242 * in this function matches the WRITE_ONCE() when @flags are modified
243 * for registered consoles with console_srcu_write_flags().
244 *
245 * Only use this function to read console flags when locklessly
246 * iterating the console list via srcu.
247 *
248 * Context: Any context.
249 */
console_srcu_read_flags(const struct console * con)250 static inline short console_srcu_read_flags(const struct console *con)
251 {
252 WARN_ON_ONCE(!console_srcu_read_lock_is_held());
253
254 /*
255 * Locklessly reading console->flags provides a consistent
256 * read value because there is at most one CPU modifying
257 * console->flags and that CPU is using only read-modify-write
258 * operations to do so.
259 */
260 return data_race(READ_ONCE(con->flags));
261 }
262
263 /**
264 * console_srcu_write_flags - Write flags for a registered console
265 * @con: struct console pointer of console to write flags to
266 * @flags: new flags value to write
267 *
268 * Only use this function to write flags for registered consoles. It
269 * requires holding the console_list_lock.
270 *
271 * Context: Any context.
272 */
console_srcu_write_flags(struct console * con,short flags)273 static inline void console_srcu_write_flags(struct console *con, short flags)
274 {
275 lockdep_assert_console_list_lock_held();
276
277 /* This matches the READ_ONCE() in console_srcu_read_flags(). */
278 WRITE_ONCE(con->flags, flags);
279 }
280
281 /* Variant of console_is_registered() when the console_list_lock is held. */
console_is_registered_locked(const struct console * con)282 static inline bool console_is_registered_locked(const struct console *con)
283 {
284 lockdep_assert_console_list_lock_held();
285 return !hlist_unhashed(&con->node);
286 }
287
288 /*
289 * console_is_registered - Check if the console is registered
290 * @con: struct console pointer of console to check
291 *
292 * Context: Process context. May sleep while acquiring console list lock.
293 * Return: true if the console is in the console list, otherwise false.
294 *
295 * If false is returned for a console that was previously registered, it
296 * can be assumed that the console's unregistration is fully completed,
297 * including the exit() callback after console list removal.
298 */
console_is_registered(const struct console * con)299 static inline bool console_is_registered(const struct console *con)
300 {
301 bool ret;
302
303 console_list_lock();
304 ret = console_is_registered_locked(con);
305 console_list_unlock();
306 return ret;
307 }
308
309 /**
310 * for_each_console_srcu() - Iterator over registered consoles
311 * @con: struct console pointer used as loop cursor
312 *
313 * Although SRCU guarantees the console list will be consistent, the
314 * struct console fields may be updated by other CPUs while iterating.
315 *
316 * Requires console_srcu_read_lock to be held. Can be invoked from
317 * any context.
318 */
319 #define for_each_console_srcu(con) \
320 hlist_for_each_entry_srcu(con, &console_list, node, \
321 console_srcu_read_lock_is_held())
322
323 /**
324 * for_each_console() - Iterator over registered consoles
325 * @con: struct console pointer used as loop cursor
326 *
327 * The console list and the console->flags are immutable while iterating.
328 *
329 * Requires console_list_lock to be held.
330 */
331 #define for_each_console(con) \
332 lockdep_assert_console_list_lock_held(); \
333 hlist_for_each_entry(con, &console_list, node)
334
335 extern int console_set_on_cmdline;
336 extern struct console *early_console;
337
338 enum con_flush_mode {
339 CONSOLE_FLUSH_PENDING,
340 CONSOLE_REPLAY_ALL,
341 };
342
343 extern int add_preferred_console(char *name, int idx, char *options);
344 extern void console_force_preferred_locked(struct console *con);
345 extern void register_console(struct console *);
346 extern int unregister_console(struct console *);
347 extern void console_lock(void);
348 extern int console_trylock(void);
349 extern void console_unlock(void);
350 extern void console_conditional_schedule(void);
351 extern void console_unblank(void);
352 extern void console_flush_on_panic(enum con_flush_mode mode);
353 extern struct tty_driver *console_device(int *);
354 extern void console_stop(struct console *);
355 extern void console_start(struct console *);
356 extern int is_console_locked(void);
357 extern int braille_register_console(struct console *, int index,
358 char *console_options, char *braille_options);
359 extern int braille_unregister_console(struct console *);
360 #ifdef CONFIG_TTY
361 extern void console_sysfs_notify(void);
362 #else
console_sysfs_notify(void)363 static inline void console_sysfs_notify(void)
364 { }
365 #endif
366 extern bool console_suspend_enabled;
367
368 /* Suspend and resume console messages over PM events */
369 extern void suspend_console(void);
370 extern void resume_console(void);
371
372 int mda_console_init(void);
373
374 void vcs_make_sysfs(int index);
375 void vcs_remove_sysfs(int index);
376
377 /* Some debug stub to catch some of the obvious races in the VT code */
378 #define WARN_CONSOLE_UNLOCKED() \
379 WARN_ON(!atomic_read(&ignore_console_lock_warning) && \
380 !is_console_locked() && !oops_in_progress)
381 /*
382 * Increment ignore_console_lock_warning if you need to quiet
383 * WARN_CONSOLE_UNLOCKED() for debugging purposes.
384 */
385 extern atomic_t ignore_console_lock_warning;
386
387 /* VESA Blanking Levels */
388 #define VESA_NO_BLANKING 0
389 #define VESA_VSYNC_SUSPEND 1
390 #define VESA_HSYNC_SUSPEND 2
391 #define VESA_POWERDOWN 3
392
393 extern void console_init(void);
394
395 /* For deferred console takeover */
396 void dummycon_register_output_notifier(struct notifier_block *nb);
397 void dummycon_unregister_output_notifier(struct notifier_block *nb);
398
399 #endif /* _LINUX_CONSOLE_H */
400