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 */ 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 lockdep_assert_console_list_lock_held(void)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 console_srcu_read_lock_is_held(void)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 */ console_srcu_read_flags(const struct console * con)247 static inline short console_srcu_read_flags(const struct console *con) 248 { 249 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 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 */ console_srcu_write_flags(struct console * con,short flags)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 WRITE_ONCE(con->flags, flags); 276 } 277 278 /* Variant of console_is_registered() when the console_list_lock is held. */ console_is_registered_locked(const struct console * con)279 static inline bool console_is_registered_locked(const struct console *con) 280 { 281 lockdep_assert_console_list_lock_held(); 282 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 */ console_is_registered(const struct console * con)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 console_sysfs_notify(void)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 */ 397