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/rculist.h> 19 #include <linux/types.h> 20 21 struct vc_data; 22 struct console_font_op; 23 struct console_font; 24 struct module; 25 struct tty_struct; 26 struct notifier_block; 27 28 enum con_scroll { 29 SM_UP, 30 SM_DOWN, 31 }; 32 33 enum vc_intensity; 34 35 /** 36 * struct consw - callbacks for consoles 37 * 38 * @con_scroll: move lines from @top to @bottom in direction @dir by @lines. 39 * Return true if no generic handling should be done. 40 * Invoked by csi_M and printing to the console. 41 * @con_set_palette: sets the palette of the console to @table (optional) 42 * @con_scrolldelta: the contents of the console should be scrolled by @lines. 43 * Invoked by user. (optional) 44 */ 45 struct consw { 46 struct module *owner; 47 const char *(*con_startup)(void); 48 void (*con_init)(struct vc_data *vc, int init); 49 void (*con_deinit)(struct vc_data *vc); 50 void (*con_clear)(struct vc_data *vc, int sy, int sx, int height, 51 int width); 52 void (*con_putc)(struct vc_data *vc, int c, int ypos, int xpos); 53 void (*con_putcs)(struct vc_data *vc, const unsigned short *s, 54 int count, int ypos, int xpos); 55 void (*con_cursor)(struct vc_data *vc, int mode); 56 bool (*con_scroll)(struct vc_data *vc, unsigned int top, 57 unsigned int bottom, enum con_scroll dir, 58 unsigned int lines); 59 int (*con_switch)(struct vc_data *vc); 60 int (*con_blank)(struct vc_data *vc, int blank, int mode_switch); 61 int (*con_font_set)(struct vc_data *vc, struct console_font *font, 62 unsigned int flags); 63 int (*con_font_get)(struct vc_data *vc, struct console_font *font); 64 int (*con_font_default)(struct vc_data *vc, 65 struct console_font *font, char *name); 66 int (*con_resize)(struct vc_data *vc, unsigned int width, 67 unsigned int height, unsigned int user); 68 void (*con_set_palette)(struct vc_data *vc, 69 const unsigned char *table); 70 void (*con_scrolldelta)(struct vc_data *vc, int lines); 71 int (*con_set_origin)(struct vc_data *vc); 72 void (*con_save_screen)(struct vc_data *vc); 73 u8 (*con_build_attr)(struct vc_data *vc, u8 color, 74 enum vc_intensity intensity, 75 bool blink, bool underline, bool reverse, bool italic); 76 void (*con_invert_region)(struct vc_data *vc, u16 *p, int count); 77 u16 *(*con_screen_pos)(const struct vc_data *vc, int offset); 78 unsigned long (*con_getxy)(struct vc_data *vc, unsigned long position, 79 int *px, int *py); 80 /* 81 * Flush the video console driver's scrollback buffer 82 */ 83 void (*con_flush_scrollback)(struct vc_data *vc); 84 /* 85 * Prepare the console for the debugger. This includes, but is not 86 * limited to, unblanking the console, loading an appropriate 87 * palette, and allowing debugger generated output. 88 */ 89 int (*con_debug_enter)(struct vc_data *vc); 90 /* 91 * Restore the console to its pre-debug state as closely as possible. 92 */ 93 int (*con_debug_leave)(struct vc_data *vc); 94 }; 95 96 extern const struct consw *conswitchp; 97 98 extern const struct consw dummy_con; /* dummy console buffer */ 99 extern const struct consw vga_con; /* VGA text console */ 100 extern const struct consw newport_con; /* SGI Newport console */ 101 102 int con_is_bound(const struct consw *csw); 103 int do_unregister_con_driver(const struct consw *csw); 104 int do_take_over_console(const struct consw *sw, int first, int last, int deflt); 105 void give_up_console(const struct consw *sw); 106 #ifdef CONFIG_HW_CONSOLE 107 int con_debug_enter(struct vc_data *vc); 108 int con_debug_leave(void); 109 #else 110 static inline int con_debug_enter(struct vc_data *vc) 111 { 112 return 0; 113 } 114 static inline int con_debug_leave(void) 115 { 116 return 0; 117 } 118 #endif 119 120 /* cursor */ 121 #define CM_DRAW (1) 122 #define CM_ERASE (2) 123 #define CM_MOVE (3) 124 125 /* 126 * The interface for a console, or any other device that wants to capture 127 * console messages (printer driver?) 128 * 129 * If a console driver is marked CON_BOOT then it will be auto-unregistered 130 * when the first real console is registered. This is for early-printk drivers. 131 */ 132 133 #define CON_PRINTBUFFER (1) 134 #define CON_CONSDEV (2) /* Preferred console, /dev/console */ 135 #define CON_ENABLED (4) 136 #define CON_BOOT (8) 137 #define CON_ANYTIME (16) /* Safe to call when cpu is offline */ 138 #define CON_BRL (32) /* Used for a braille device */ 139 #define CON_EXTENDED (64) /* Use the extended output format a la /dev/kmsg */ 140 141 struct console { 142 char name[16]; 143 void (*write)(struct console *, const char *, unsigned); 144 int (*read)(struct console *, char *, unsigned); 145 struct tty_driver *(*device)(struct console *, int *); 146 void (*unblank)(void); 147 int (*setup)(struct console *, char *); 148 int (*exit)(struct console *); 149 int (*match)(struct console *, char *name, int idx, char *options); 150 short flags; 151 short index; 152 int cflag; 153 uint ispeed; 154 uint ospeed; 155 u64 seq; 156 unsigned long dropped; 157 void *data; 158 struct hlist_node node; 159 }; 160 161 #ifdef CONFIG_LOCKDEP 162 extern void lockdep_assert_console_list_lock_held(void); 163 #else 164 static inline void lockdep_assert_console_list_lock_held(void) 165 { 166 } 167 #endif 168 169 #ifdef CONFIG_DEBUG_LOCK_ALLOC 170 extern bool console_srcu_read_lock_is_held(void); 171 #else 172 static inline bool console_srcu_read_lock_is_held(void) 173 { 174 return 1; 175 } 176 #endif 177 178 extern int console_srcu_read_lock(void); 179 extern void console_srcu_read_unlock(int cookie); 180 181 extern void console_list_lock(void) __acquires(console_mutex); 182 extern void console_list_unlock(void) __releases(console_mutex); 183 184 extern struct hlist_head console_list; 185 186 /** 187 * console_srcu_read_flags - Locklessly read the console flags 188 * @con: struct console pointer of console to read flags from 189 * 190 * This function provides the necessary READ_ONCE() and data_race() 191 * notation for locklessly reading the console flags. The READ_ONCE() 192 * in this function matches the WRITE_ONCE() when @flags are modified 193 * for registered consoles with console_srcu_write_flags(). 194 * 195 * Only use this function to read console flags when locklessly 196 * iterating the console list via srcu. 197 * 198 * Context: Any context. 199 */ 200 static inline short console_srcu_read_flags(const struct console *con) 201 { 202 WARN_ON_ONCE(!console_srcu_read_lock_is_held()); 203 204 /* 205 * Locklessly reading console->flags provides a consistent 206 * read value because there is at most one CPU modifying 207 * console->flags and that CPU is using only read-modify-write 208 * operations to do so. 209 */ 210 return data_race(READ_ONCE(con->flags)); 211 } 212 213 /** 214 * console_srcu_write_flags - Write flags for a registered console 215 * @con: struct console pointer of console to write flags to 216 * @flags: new flags value to write 217 * 218 * Only use this function to write flags for registered consoles. It 219 * requires holding the console_list_lock. 220 * 221 * Context: Any context. 222 */ 223 static inline void console_srcu_write_flags(struct console *con, short flags) 224 { 225 lockdep_assert_console_list_lock_held(); 226 227 /* This matches the READ_ONCE() in console_srcu_read_flags(). */ 228 WRITE_ONCE(con->flags, flags); 229 } 230 231 /* Variant of console_is_registered() when the console_list_lock is held. */ 232 static inline bool console_is_registered_locked(const struct console *con) 233 { 234 lockdep_assert_console_list_lock_held(); 235 return !hlist_unhashed(&con->node); 236 } 237 238 /* 239 * console_is_registered - Check if the console is registered 240 * @con: struct console pointer of console to check 241 * 242 * Context: Process context. May sleep while acquiring console list lock. 243 * Return: true if the console is in the console list, otherwise false. 244 * 245 * If false is returned for a console that was previously registered, it 246 * can be assumed that the console's unregistration is fully completed, 247 * including the exit() callback after console list removal. 248 */ 249 static inline bool console_is_registered(const struct console *con) 250 { 251 bool ret; 252 253 console_list_lock(); 254 ret = console_is_registered_locked(con); 255 console_list_unlock(); 256 return ret; 257 } 258 259 /** 260 * for_each_console_srcu() - Iterator over registered consoles 261 * @con: struct console pointer used as loop cursor 262 * 263 * Although SRCU guarantees the console list will be consistent, the 264 * struct console fields may be updated by other CPUs while iterating. 265 * 266 * Requires console_srcu_read_lock to be held. Can be invoked from 267 * any context. 268 */ 269 #define for_each_console_srcu(con) \ 270 hlist_for_each_entry_srcu(con, &console_list, node, \ 271 console_srcu_read_lock_is_held()) 272 273 /** 274 * for_each_console() - Iterator over registered consoles 275 * @con: struct console pointer used as loop cursor 276 * 277 * The console list and the console->flags are immutable while iterating. 278 * 279 * Requires console_list_lock to be held. 280 */ 281 #define for_each_console(con) \ 282 lockdep_assert_console_list_lock_held(); \ 283 hlist_for_each_entry(con, &console_list, node) 284 285 extern int console_set_on_cmdline; 286 extern struct console *early_console; 287 288 enum con_flush_mode { 289 CONSOLE_FLUSH_PENDING, 290 CONSOLE_REPLAY_ALL, 291 }; 292 293 extern int add_preferred_console(char *name, int idx, char *options); 294 extern void console_force_preferred_locked(struct console *con); 295 extern void register_console(struct console *); 296 extern int unregister_console(struct console *); 297 extern void console_lock(void); 298 extern int console_trylock(void); 299 extern void console_unlock(void); 300 extern void console_conditional_schedule(void); 301 extern void console_unblank(void); 302 extern void console_flush_on_panic(enum con_flush_mode mode); 303 extern struct tty_driver *console_device(int *); 304 extern void console_stop(struct console *); 305 extern void console_start(struct console *); 306 extern int is_console_locked(void); 307 extern int braille_register_console(struct console *, int index, 308 char *console_options, char *braille_options); 309 extern int braille_unregister_console(struct console *); 310 #ifdef CONFIG_TTY 311 extern void console_sysfs_notify(void); 312 #else 313 static inline void console_sysfs_notify(void) 314 { } 315 #endif 316 extern bool console_suspend_enabled; 317 318 /* Suspend and resume console messages over PM events */ 319 extern void suspend_console(void); 320 extern void resume_console(void); 321 322 int mda_console_init(void); 323 324 void vcs_make_sysfs(int index); 325 void vcs_remove_sysfs(int index); 326 327 /* Some debug stub to catch some of the obvious races in the VT code */ 328 #define WARN_CONSOLE_UNLOCKED() \ 329 WARN_ON(!atomic_read(&ignore_console_lock_warning) && \ 330 !is_console_locked() && !oops_in_progress) 331 /* 332 * Increment ignore_console_lock_warning if you need to quiet 333 * WARN_CONSOLE_UNLOCKED() for debugging purposes. 334 */ 335 extern atomic_t ignore_console_lock_warning; 336 337 /* VESA Blanking Levels */ 338 #define VESA_NO_BLANKING 0 339 #define VESA_VSYNC_SUSPEND 1 340 #define VESA_HSYNC_SUSPEND 2 341 #define VESA_POWERDOWN 3 342 343 extern void console_init(void); 344 345 /* For deferred console takeover */ 346 void dummycon_register_output_notifier(struct notifier_block *nb); 347 void dummycon_unregister_output_notifier(struct notifier_block *nb); 348 349 #endif /* _LINUX_CONSOLE_H */ 350