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 struct screen_info; 105 #ifdef CONFIG_VGA_CONSOLE 106 void vgacon_register_screen(struct screen_info *si); 107 #else 108 static inline void vgacon_register_screen(struct screen_info *si) { } 109 #endif 110 111 int con_is_bound(const struct consw *csw); 112 int do_unregister_con_driver(const struct consw *csw); 113 int do_take_over_console(const struct consw *sw, int first, int last, int deflt); 114 void give_up_console(const struct consw *sw); 115 #ifdef CONFIG_HW_CONSOLE 116 int con_debug_enter(struct vc_data *vc); 117 int con_debug_leave(void); 118 #else 119 static inline int con_debug_enter(struct vc_data *vc) 120 { 121 return 0; 122 } 123 static inline int con_debug_leave(void) 124 { 125 return 0; 126 } 127 #endif 128 129 /* cursor */ 130 #define CM_DRAW (1) 131 #define CM_ERASE (2) 132 #define CM_MOVE (3) 133 134 /* 135 * The interface for a console, or any other device that wants to capture 136 * console messages (printer driver?) 137 */ 138 139 /** 140 * cons_flags - General console flags 141 * @CON_PRINTBUFFER: Used by newly registered consoles to avoid duplicate 142 * output of messages that were already shown by boot 143 * consoles or read by userspace via syslog() syscall. 144 * @CON_CONSDEV: Indicates that the console driver is backing 145 * /dev/console. 146 * @CON_ENABLED: Indicates if a console is allowed to print records. If 147 * false, the console also will not advance to later 148 * records. 149 * @CON_BOOT: Marks the console driver as early console driver which 150 * is used during boot before the real driver becomes 151 * available. It will be automatically unregistered 152 * when the real console driver is registered unless 153 * "keep_bootcon" parameter is used. 154 * @CON_ANYTIME: A misnomed historical flag which tells the core code 155 * that the legacy @console::write callback can be invoked 156 * on a CPU which is marked OFFLINE. That is misleading as 157 * it suggests that there is no contextual limit for 158 * invoking the callback. The original motivation was 159 * readiness of the per-CPU areas. 160 * @CON_BRL: Indicates a braille device which is exempt from 161 * receiving the printk spam for obvious reasons. 162 * @CON_EXTENDED: The console supports the extended output format of 163 * /dev/kmesg which requires a larger output buffer. 164 * @CON_SUSPENDED: Indicates if a console is suspended. If true, the 165 * printing callbacks must not be called. 166 */ 167 enum cons_flags { 168 CON_PRINTBUFFER = BIT(0), 169 CON_CONSDEV = BIT(1), 170 CON_ENABLED = BIT(2), 171 CON_BOOT = BIT(3), 172 CON_ANYTIME = BIT(4), 173 CON_BRL = BIT(5), 174 CON_EXTENDED = BIT(6), 175 CON_SUSPENDED = BIT(7), 176 }; 177 178 /** 179 * struct console - The console descriptor structure 180 * @name: The name of the console driver 181 * @write: Write callback to output messages (Optional) 182 * @read: Read callback for console input (Optional) 183 * @device: The underlying TTY device driver (Optional) 184 * @unblank: Callback to unblank the console (Optional) 185 * @setup: Callback for initializing the console (Optional) 186 * @exit: Callback for teardown of the console (Optional) 187 * @match: Callback for matching a console (Optional) 188 * @flags: Console flags. See enum cons_flags 189 * @index: Console index, e.g. port number 190 * @cflag: TTY control mode flags 191 * @ispeed: TTY input speed 192 * @ospeed: TTY output speed 193 * @seq: Sequence number of the next ringbuffer record to print 194 * @dropped: Number of unreported dropped ringbuffer records 195 * @data: Driver private data 196 * @node: hlist node for the console list 197 */ 198 struct console { 199 char name[16]; 200 void (*write)(struct console *co, const char *s, unsigned int count); 201 int (*read)(struct console *co, char *s, unsigned int count); 202 struct tty_driver *(*device)(struct console *co, int *index); 203 void (*unblank)(void); 204 int (*setup)(struct console *co, char *options); 205 int (*exit)(struct console *co); 206 int (*match)(struct console *co, char *name, int idx, char *options); 207 short flags; 208 short index; 209 int cflag; 210 uint ispeed; 211 uint ospeed; 212 u64 seq; 213 unsigned long dropped; 214 void *data; 215 struct hlist_node node; 216 }; 217 218 #ifdef CONFIG_LOCKDEP 219 extern void lockdep_assert_console_list_lock_held(void); 220 #else 221 static inline void lockdep_assert_console_list_lock_held(void) 222 { 223 } 224 #endif 225 226 #ifdef CONFIG_DEBUG_LOCK_ALLOC 227 extern bool console_srcu_read_lock_is_held(void); 228 #else 229 static inline bool console_srcu_read_lock_is_held(void) 230 { 231 return 1; 232 } 233 #endif 234 235 extern int console_srcu_read_lock(void); 236 extern void console_srcu_read_unlock(int cookie); 237 238 extern void console_list_lock(void) __acquires(console_mutex); 239 extern void console_list_unlock(void) __releases(console_mutex); 240 241 extern struct hlist_head console_list; 242 243 /** 244 * console_srcu_read_flags - Locklessly read the console flags 245 * @con: struct console pointer of console to read flags from 246 * 247 * This function provides the necessary READ_ONCE() and data_race() 248 * notation for locklessly reading the console flags. The READ_ONCE() 249 * in this function matches the WRITE_ONCE() when @flags are modified 250 * for registered consoles with console_srcu_write_flags(). 251 * 252 * Only use this function to read console flags when locklessly 253 * iterating the console list via srcu. 254 * 255 * Context: Any context. 256 */ 257 static inline short console_srcu_read_flags(const struct console *con) 258 { 259 WARN_ON_ONCE(!console_srcu_read_lock_is_held()); 260 261 /* 262 * Locklessly reading console->flags provides a consistent 263 * read value because there is at most one CPU modifying 264 * console->flags and that CPU is using only read-modify-write 265 * operations to do so. 266 */ 267 return data_race(READ_ONCE(con->flags)); 268 } 269 270 /** 271 * console_srcu_write_flags - Write flags for a registered console 272 * @con: struct console pointer of console to write flags to 273 * @flags: new flags value to write 274 * 275 * Only use this function to write flags for registered consoles. It 276 * requires holding the console_list_lock. 277 * 278 * Context: Any context. 279 */ 280 static inline void console_srcu_write_flags(struct console *con, short flags) 281 { 282 lockdep_assert_console_list_lock_held(); 283 284 /* This matches the READ_ONCE() in console_srcu_read_flags(). */ 285 WRITE_ONCE(con->flags, flags); 286 } 287 288 /* Variant of console_is_registered() when the console_list_lock is held. */ 289 static inline bool console_is_registered_locked(const struct console *con) 290 { 291 lockdep_assert_console_list_lock_held(); 292 return !hlist_unhashed(&con->node); 293 } 294 295 /* 296 * console_is_registered - Check if the console is registered 297 * @con: struct console pointer of console to check 298 * 299 * Context: Process context. May sleep while acquiring console list lock. 300 * Return: true if the console is in the console list, otherwise false. 301 * 302 * If false is returned for a console that was previously registered, it 303 * can be assumed that the console's unregistration is fully completed, 304 * including the exit() callback after console list removal. 305 */ 306 static inline bool console_is_registered(const struct console *con) 307 { 308 bool ret; 309 310 console_list_lock(); 311 ret = console_is_registered_locked(con); 312 console_list_unlock(); 313 return ret; 314 } 315 316 /** 317 * for_each_console_srcu() - Iterator over registered consoles 318 * @con: struct console pointer used as loop cursor 319 * 320 * Although SRCU guarantees the console list will be consistent, the 321 * struct console fields may be updated by other CPUs while iterating. 322 * 323 * Requires console_srcu_read_lock to be held. Can be invoked from 324 * any context. 325 */ 326 #define for_each_console_srcu(con) \ 327 hlist_for_each_entry_srcu(con, &console_list, node, \ 328 console_srcu_read_lock_is_held()) 329 330 /** 331 * for_each_console() - Iterator over registered consoles 332 * @con: struct console pointer used as loop cursor 333 * 334 * The console list and the console->flags are immutable while iterating. 335 * 336 * Requires console_list_lock to be held. 337 */ 338 #define for_each_console(con) \ 339 lockdep_assert_console_list_lock_held(); \ 340 hlist_for_each_entry(con, &console_list, node) 341 342 extern int console_set_on_cmdline; 343 extern struct console *early_console; 344 345 enum con_flush_mode { 346 CONSOLE_FLUSH_PENDING, 347 CONSOLE_REPLAY_ALL, 348 }; 349 350 extern int add_preferred_console(char *name, int idx, char *options); 351 extern void console_force_preferred_locked(struct console *con); 352 extern void register_console(struct console *); 353 extern int unregister_console(struct console *); 354 extern void console_lock(void); 355 extern int console_trylock(void); 356 extern void console_unlock(void); 357 extern void console_conditional_schedule(void); 358 extern void console_unblank(void); 359 extern void console_flush_on_panic(enum con_flush_mode mode); 360 extern struct tty_driver *console_device(int *); 361 extern void console_stop(struct console *); 362 extern void console_start(struct console *); 363 extern int is_console_locked(void); 364 extern int braille_register_console(struct console *, int index, 365 char *console_options, char *braille_options); 366 extern int braille_unregister_console(struct console *); 367 #ifdef CONFIG_TTY 368 extern void console_sysfs_notify(void); 369 #else 370 static inline void console_sysfs_notify(void) 371 { } 372 #endif 373 extern bool console_suspend_enabled; 374 375 /* Suspend and resume console messages over PM events */ 376 extern void suspend_console(void); 377 extern void resume_console(void); 378 379 int mda_console_init(void); 380 381 void vcs_make_sysfs(int index); 382 void vcs_remove_sysfs(int index); 383 384 /* Some debug stub to catch some of the obvious races in the VT code */ 385 #define WARN_CONSOLE_UNLOCKED() \ 386 WARN_ON(!atomic_read(&ignore_console_lock_warning) && \ 387 !is_console_locked() && !oops_in_progress) 388 /* 389 * Increment ignore_console_lock_warning if you need to quiet 390 * WARN_CONSOLE_UNLOCKED() for debugging purposes. 391 */ 392 extern atomic_t ignore_console_lock_warning; 393 394 /* VESA Blanking Levels */ 395 #define VESA_NO_BLANKING 0 396 #define VESA_VSYNC_SUSPEND 1 397 #define VESA_HSYNC_SUSPEND 2 398 #define VESA_POWERDOWN 3 399 400 extern void console_init(void); 401 402 /* For deferred console takeover */ 403 void dummycon_register_output_notifier(struct notifier_block *nb); 404 void dummycon_unregister_output_notifier(struct notifier_block *nb); 405 406 #endif /* _LINUX_CONSOLE_H */ 407