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 vpitch, unsigned int flags); 63 int (*con_font_get)(struct vc_data *vc, struct console_font *font, 64 unsigned int vpitch); 65 int (*con_font_default)(struct vc_data *vc, 66 struct console_font *font, char *name); 67 int (*con_resize)(struct vc_data *vc, unsigned int width, 68 unsigned int height, unsigned int user); 69 void (*con_set_palette)(struct vc_data *vc, 70 const unsigned char *table); 71 void (*con_scrolldelta)(struct vc_data *vc, int lines); 72 int (*con_set_origin)(struct vc_data *vc); 73 void (*con_save_screen)(struct vc_data *vc); 74 u8 (*con_build_attr)(struct vc_data *vc, u8 color, 75 enum vc_intensity intensity, 76 bool blink, bool underline, bool reverse, bool italic); 77 void (*con_invert_region)(struct vc_data *vc, u16 *p, int count); 78 u16 *(*con_screen_pos)(const struct vc_data *vc, int offset); 79 unsigned long (*con_getxy)(struct vc_data *vc, unsigned long position, 80 int *px, int *py); 81 /* 82 * Flush the video console driver's scrollback buffer 83 */ 84 void (*con_flush_scrollback)(struct vc_data *vc); 85 /* 86 * Prepare the console for the debugger. This includes, but is not 87 * limited to, unblanking the console, loading an appropriate 88 * palette, and allowing debugger generated output. 89 */ 90 int (*con_debug_enter)(struct vc_data *vc); 91 /* 92 * Restore the console to its pre-debug state as closely as possible. 93 */ 94 int (*con_debug_leave)(struct vc_data *vc); 95 }; 96 97 extern const struct consw *conswitchp; 98 99 extern const struct consw dummy_con; /* dummy console buffer */ 100 extern const struct consw vga_con; /* VGA text console */ 101 extern const struct consw newport_con; /* SGI Newport console */ 102 103 int con_is_bound(const struct consw *csw); 104 int do_unregister_con_driver(const struct consw *csw); 105 int do_take_over_console(const struct consw *sw, int first, int last, int deflt); 106 void give_up_console(const struct consw *sw); 107 #ifdef CONFIG_HW_CONSOLE 108 int con_debug_enter(struct vc_data *vc); 109 int con_debug_leave(void); 110 #else 111 static inline int con_debug_enter(struct vc_data *vc) 112 { 113 return 0; 114 } 115 static inline int con_debug_leave(void) 116 { 117 return 0; 118 } 119 #endif 120 121 /* cursor */ 122 #define CM_DRAW (1) 123 #define CM_ERASE (2) 124 #define CM_MOVE (3) 125 126 /* 127 * The interface for a console, or any other device that wants to capture 128 * console messages (printer driver?) 129 * 130 * If a console driver is marked CON_BOOT then it will be auto-unregistered 131 * when the first real console is registered. This is for early-printk drivers. 132 */ 133 134 #define CON_PRINTBUFFER (1) 135 #define CON_CONSDEV (2) /* Preferred console, /dev/console */ 136 #define CON_ENABLED (4) 137 #define CON_BOOT (8) 138 #define CON_ANYTIME (16) /* Safe to call when cpu is offline */ 139 #define CON_BRL (32) /* Used for a braille device */ 140 #define CON_EXTENDED (64) /* Use the extended output format a la /dev/kmsg */ 141 142 struct console { 143 char name[16]; 144 void (*write)(struct console *, const char *, unsigned); 145 int (*read)(struct console *, char *, unsigned); 146 struct tty_driver *(*device)(struct console *, int *); 147 void (*unblank)(void); 148 int (*setup)(struct console *, char *); 149 int (*exit)(struct console *); 150 int (*match)(struct console *, char *name, int idx, char *options); 151 short flags; 152 short index; 153 int cflag; 154 uint ispeed; 155 uint ospeed; 156 u64 seq; 157 unsigned long dropped; 158 void *data; 159 struct hlist_node node; 160 }; 161 162 #ifdef CONFIG_LOCKDEP 163 extern void lockdep_assert_console_list_lock_held(void); 164 #else 165 static inline void lockdep_assert_console_list_lock_held(void) 166 { 167 } 168 #endif 169 170 #ifdef CONFIG_DEBUG_LOCK_ALLOC 171 extern bool console_srcu_read_lock_is_held(void); 172 #else 173 static inline bool console_srcu_read_lock_is_held(void) 174 { 175 return 1; 176 } 177 #endif 178 179 extern int console_srcu_read_lock(void); 180 extern void console_srcu_read_unlock(int cookie); 181 182 extern void console_list_lock(void) __acquires(console_mutex); 183 extern void console_list_unlock(void) __releases(console_mutex); 184 185 extern struct hlist_head console_list; 186 187 /** 188 * console_srcu_read_flags - Locklessly read the console flags 189 * @con: struct console pointer of console to read flags from 190 * 191 * This function provides the necessary READ_ONCE() and data_race() 192 * notation for locklessly reading the console flags. The READ_ONCE() 193 * in this function matches the WRITE_ONCE() when @flags are modified 194 * for registered consoles with console_srcu_write_flags(). 195 * 196 * Only use this function to read console flags when locklessly 197 * iterating the console list via srcu. 198 * 199 * Context: Any context. 200 */ 201 static inline short console_srcu_read_flags(const struct console *con) 202 { 203 WARN_ON_ONCE(!console_srcu_read_lock_is_held()); 204 205 /* 206 * Locklessly reading console->flags provides a consistent 207 * read value because there is at most one CPU modifying 208 * console->flags and that CPU is using only read-modify-write 209 * operations to do so. 210 */ 211 return data_race(READ_ONCE(con->flags)); 212 } 213 214 /** 215 * console_srcu_write_flags - Write flags for a registered console 216 * @con: struct console pointer of console to write flags to 217 * @flags: new flags value to write 218 * 219 * Only use this function to write flags for registered consoles. It 220 * requires holding the console_list_lock. 221 * 222 * Context: Any context. 223 */ 224 static inline void console_srcu_write_flags(struct console *con, short flags) 225 { 226 lockdep_assert_console_list_lock_held(); 227 228 /* This matches the READ_ONCE() in console_srcu_read_flags(). */ 229 WRITE_ONCE(con->flags, flags); 230 } 231 232 /* Variant of console_is_registered() when the console_list_lock is held. */ 233 static inline bool console_is_registered_locked(const struct console *con) 234 { 235 lockdep_assert_console_list_lock_held(); 236 return !hlist_unhashed(&con->node); 237 } 238 239 /* 240 * console_is_registered - Check if the console is registered 241 * @con: struct console pointer of console to check 242 * 243 * Context: Process context. May sleep while acquiring console list lock. 244 * Return: true if the console is in the console list, otherwise false. 245 * 246 * If false is returned for a console that was previously registered, it 247 * can be assumed that the console's unregistration is fully completed, 248 * including the exit() callback after console list removal. 249 */ 250 static inline bool console_is_registered(const struct console *con) 251 { 252 bool ret; 253 254 console_list_lock(); 255 ret = console_is_registered_locked(con); 256 console_list_unlock(); 257 return ret; 258 } 259 260 /** 261 * for_each_console_srcu() - Iterator over registered consoles 262 * @con: struct console pointer used as loop cursor 263 * 264 * Although SRCU guarantees the console list will be consistent, the 265 * struct console fields may be updated by other CPUs while iterating. 266 * 267 * Requires console_srcu_read_lock to be held. Can be invoked from 268 * any context. 269 */ 270 #define for_each_console_srcu(con) \ 271 hlist_for_each_entry_srcu(con, &console_list, node, \ 272 console_srcu_read_lock_is_held()) 273 274 /** 275 * for_each_console() - Iterator over registered consoles 276 * @con: struct console pointer used as loop cursor 277 * 278 * The console list and the console->flags are immutable while iterating. 279 * 280 * Requires console_list_lock to be held. 281 */ 282 #define for_each_console(con) \ 283 lockdep_assert_console_list_lock_held(); \ 284 hlist_for_each_entry(con, &console_list, node) 285 286 extern int console_set_on_cmdline; 287 extern struct console *early_console; 288 289 enum con_flush_mode { 290 CONSOLE_FLUSH_PENDING, 291 CONSOLE_REPLAY_ALL, 292 }; 293 294 extern int add_preferred_console(char *name, int idx, char *options); 295 extern void console_force_preferred_locked(struct console *con); 296 extern void register_console(struct console *); 297 extern int unregister_console(struct console *); 298 extern void console_lock(void); 299 extern int console_trylock(void); 300 extern void console_unlock(void); 301 extern void console_conditional_schedule(void); 302 extern void console_unblank(void); 303 extern void console_flush_on_panic(enum con_flush_mode mode); 304 extern struct tty_driver *console_device(int *); 305 extern void console_stop(struct console *); 306 extern void console_start(struct console *); 307 extern int is_console_locked(void); 308 extern int braille_register_console(struct console *, int index, 309 char *console_options, char *braille_options); 310 extern int braille_unregister_console(struct console *); 311 #ifdef CONFIG_TTY 312 extern void console_sysfs_notify(void); 313 #else 314 static inline void console_sysfs_notify(void) 315 { } 316 #endif 317 extern bool console_suspend_enabled; 318 319 /* Suspend and resume console messages over PM events */ 320 extern void suspend_console(void); 321 extern void resume_console(void); 322 323 int mda_console_init(void); 324 325 void vcs_make_sysfs(int index); 326 void vcs_remove_sysfs(int index); 327 328 /* Some debug stub to catch some of the obvious races in the VT code */ 329 #define WARN_CONSOLE_UNLOCKED() \ 330 WARN_ON(!atomic_read(&ignore_console_lock_warning) && \ 331 !is_console_locked() && !oops_in_progress) 332 /* 333 * Increment ignore_console_lock_warning if you need to quiet 334 * WARN_CONSOLE_UNLOCKED() for debugging purposes. 335 */ 336 extern atomic_t ignore_console_lock_warning; 337 338 /* VESA Blanking Levels */ 339 #define VESA_NO_BLANKING 0 340 #define VESA_VSYNC_SUSPEND 1 341 #define VESA_HSYNC_SUSPEND 2 342 #define VESA_POWERDOWN 3 343 344 extern void console_init(void); 345 346 /* For deferred console takeover */ 347 void dummycon_register_output_notifier(struct notifier_block *nb); 348 void dummycon_unregister_output_notifier(struct notifier_block *nb); 349 350 #endif /* _LINUX_CONSOLE_H */ 351