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Diffstat (limited to 'include/linux/console.h')
| -rw-r--r-- | include/linux/console.h | 399 |
1 files changed, 399 insertions, 0 deletions
diff --git a/include/linux/console.h b/include/linux/console.h new file mode 100644 index 000000000..7de11c763 --- /dev/null +++ b/include/linux/console.h @@ -0,0 +1,399 @@ +/* + * linux/include/linux/console.h + * + * Copyright (C) 1993 Hamish Macdonald + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file COPYING in the main directory of this archive + * for more details. + * + * Changed: + * 10-Mar-94: Arno Griffioen: Conversion for vt100 emulator port from PC LINUX + */ + +#ifndef _LINUX_CONSOLE_H_ +#define _LINUX_CONSOLE_H_ 1 + +#include <linux/atomic.h> +#include <linux/bits.h> +#include <linux/rculist.h> +#include <linux/types.h> + +struct vc_data; +struct console_font_op; +struct console_font; +struct module; +struct tty_struct; +struct notifier_block; + +enum con_scroll { + SM_UP, + SM_DOWN, +}; + +enum vc_intensity; + +/** + * struct consw - callbacks for consoles + * + * @con_scroll: move lines from @top to @bottom in direction @dir by @lines. + * Return true if no generic handling should be done. + * Invoked by csi_M and printing to the console. + * @con_set_palette: sets the palette of the console to @table (optional) + * @con_scrolldelta: the contents of the console should be scrolled by @lines. + * Invoked by user. (optional) + */ +struct consw { + struct module *owner; + const char *(*con_startup)(void); + void (*con_init)(struct vc_data *vc, int init); + void (*con_deinit)(struct vc_data *vc); + void (*con_clear)(struct vc_data *vc, int sy, int sx, int height, + int width); + void (*con_putc)(struct vc_data *vc, int c, int ypos, int xpos); + void (*con_putcs)(struct vc_data *vc, const unsigned short *s, + int count, int ypos, int xpos); + void (*con_cursor)(struct vc_data *vc, int mode); + bool (*con_scroll)(struct vc_data *vc, unsigned int top, + unsigned int bottom, enum con_scroll dir, + unsigned int lines); + int (*con_switch)(struct vc_data *vc); + int (*con_blank)(struct vc_data *vc, int blank, int mode_switch); + int (*con_font_set)(struct vc_data *vc, struct console_font *font, + unsigned int vpitch, unsigned int flags); + int (*con_font_get)(struct vc_data *vc, struct console_font *font, + unsigned int vpitch); + int (*con_font_default)(struct vc_data *vc, + struct console_font *font, char *name); + int (*con_resize)(struct vc_data *vc, unsigned int width, + unsigned int height, unsigned int user); + void (*con_set_palette)(struct vc_data *vc, + const unsigned char *table); + void (*con_scrolldelta)(struct vc_data *vc, int lines); + int (*con_set_origin)(struct vc_data *vc); + void (*con_save_screen)(struct vc_data *vc); + u8 (*con_build_attr)(struct vc_data *vc, u8 color, + enum vc_intensity intensity, + bool blink, bool underline, bool reverse, bool italic); + void (*con_invert_region)(struct vc_data *vc, u16 *p, int count); + u16 *(*con_screen_pos)(const struct vc_data *vc, int offset); + unsigned long (*con_getxy)(struct vc_data *vc, unsigned long position, + int *px, int *py); + /* + * Flush the video console driver's scrollback buffer + */ + void (*con_flush_scrollback)(struct vc_data *vc); + /* + * Prepare the console for the debugger. This includes, but is not + * limited to, unblanking the console, loading an appropriate + * palette, and allowing debugger generated output. + */ + int (*con_debug_enter)(struct vc_data *vc); + /* + * Restore the console to its pre-debug state as closely as possible. + */ + int (*con_debug_leave)(struct vc_data *vc); +}; + +extern const struct consw *conswitchp; + +extern const struct consw dummy_con; /* dummy console buffer */ +extern const struct consw vga_con; /* VGA text console */ +extern const struct consw newport_con; /* SGI Newport console */ + +int con_is_bound(const struct consw *csw); +int do_unregister_con_driver(const struct consw *csw); +int do_take_over_console(const struct consw *sw, int first, int last, int deflt); +void give_up_console(const struct consw *sw); +#ifdef CONFIG_HW_CONSOLE +int con_debug_enter(struct vc_data *vc); +int con_debug_leave(void); +#else +static inline int con_debug_enter(struct vc_data *vc) +{ + return 0; +} +static inline int con_debug_leave(void) +{ + return 0; +} +#endif + +/* cursor */ +#define CM_DRAW (1) +#define CM_ERASE (2) +#define CM_MOVE (3) + +/* + * The interface for a console, or any other device that wants to capture + * console messages (printer driver?) + */ + +/** + * cons_flags - General console flags + * @CON_PRINTBUFFER: Used by newly registered consoles to avoid duplicate + * output of messages that were already shown by boot + * consoles or read by userspace via syslog() syscall. + * @CON_CONSDEV: Indicates that the console driver is backing + * /dev/console. + * @CON_ENABLED: Indicates if a console is allowed to print records. If + * false, the console also will not advance to later + * records. + * @CON_BOOT: Marks the console driver as early console driver which + * is used during boot before the real driver becomes + * available. It will be automatically unregistered + * when the real console driver is registered unless + * "keep_bootcon" parameter is used. + * @CON_ANYTIME: A misnomed historical flag which tells the core code + * that the legacy @console::write callback can be invoked + * on a CPU which is marked OFFLINE. That is misleading as + * it suggests that there is no contextual limit for + * invoking the callback. The original motivation was + * readiness of the per-CPU areas. + * @CON_BRL: Indicates a braille device which is exempt from + * receiving the printk spam for obvious reasons. + * @CON_EXTENDED: The console supports the extended output format of + * /dev/kmesg which requires a larger output buffer. + * @CON_SUSPENDED: Indicates if a console is suspended. If true, the + * printing callbacks must not be called. + */ +enum cons_flags { + CON_PRINTBUFFER = BIT(0), + CON_CONSDEV = BIT(1), + CON_ENABLED = BIT(2), + CON_BOOT = BIT(3), + CON_ANYTIME = BIT(4), + CON_BRL = BIT(5), + CON_EXTENDED = BIT(6), + CON_SUSPENDED = BIT(7), +}; + +/** + * struct console - The console descriptor structure + * @name: The name of the console driver + * @write: Write callback to output messages (Optional) + * @read: Read callback for console input (Optional) + * @device: The underlying TTY device driver (Optional) + * @unblank: Callback to unblank the console (Optional) + * @setup: Callback for initializing the console (Optional) + * @exit: Callback for teardown of the console (Optional) + * @match: Callback for matching a console (Optional) + * @flags: Console flags. See enum cons_flags + * @index: Console index, e.g. port number + * @cflag: TTY control mode flags + * @ispeed: TTY input speed + * @ospeed: TTY output speed + * @seq: Sequence number of the next ringbuffer record to print + * @dropped: Number of unreported dropped ringbuffer records + * @data: Driver private data + * @node: hlist node for the console list + */ +struct console { + char name[16]; + void (*write)(struct console *co, const char *s, unsigned int count); + int (*read)(struct console *co, char *s, unsigned int count); + struct tty_driver *(*device)(struct console *co, int *index); + void (*unblank)(void); + int (*setup)(struct console *co, char *options); + int (*exit)(struct console *co); + int (*match)(struct console *co, char *name, int idx, char *options); + short flags; + short index; + int cflag; + uint ispeed; + uint ospeed; + u64 seq; + unsigned long dropped; + void *data; + struct hlist_node node; +}; + +#ifdef CONFIG_LOCKDEP +extern void lockdep_assert_console_list_lock_held(void); +#else +static inline void lockdep_assert_console_list_lock_held(void) +{ +} +#endif + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +extern bool console_srcu_read_lock_is_held(void); +#else +static inline bool console_srcu_read_lock_is_held(void) +{ + return 1; +} +#endif + +extern int console_srcu_read_lock(void); +extern void console_srcu_read_unlock(int cookie); + +extern void console_list_lock(void) __acquires(console_mutex); +extern void console_list_unlock(void) __releases(console_mutex); + +extern struct hlist_head console_list; + +/** + * console_srcu_read_flags - Locklessly read the console flags + * @con: struct console pointer of console to read flags from + * + * This function provides the necessary READ_ONCE() and data_race() + * notation for locklessly reading the console flags. The READ_ONCE() + * in this function matches the WRITE_ONCE() when @flags are modified + * for registered consoles with console_srcu_write_flags(). + * + * Only use this function to read console flags when locklessly + * iterating the console list via srcu. + * + * Context: Any context. + */ +static inline short console_srcu_read_flags(const struct console *con) +{ + WARN_ON_ONCE(!console_srcu_read_lock_is_held()); + + /* + * Locklessly reading console->flags provides a consistent + * read value because there is at most one CPU modifying + * console->flags and that CPU is using only read-modify-write + * operations to do so. + */ + return data_race(READ_ONCE(con->flags)); +} + +/** + * console_srcu_write_flags - Write flags for a registered console + * @con: struct console pointer of console to write flags to + * @flags: new flags value to write + * + * Only use this function to write flags for registered consoles. It + * requires holding the console_list_lock. + * + * Context: Any context. + */ +static inline void console_srcu_write_flags(struct console *con, short flags) +{ + lockdep_assert_console_list_lock_held(); + + /* This matches the READ_ONCE() in console_srcu_read_flags(). */ + WRITE_ONCE(con->flags, flags); +} + +/* Variant of console_is_registered() when the console_list_lock is held. */ +static inline bool console_is_registered_locked(const struct console *con) +{ + lockdep_assert_console_list_lock_held(); + return !hlist_unhashed(&con->node); +} + +/* + * console_is_registered - Check if the console is registered + * @con: struct console pointer of console to check + * + * Context: Process context. May sleep while acquiring console list lock. + * Return: true if the console is in the console list, otherwise false. + * + * If false is returned for a console that was previously registered, it + * can be assumed that the console's unregistration is fully completed, + * including the exit() callback after console list removal. + */ +static inline bool console_is_registered(const struct console *con) +{ + bool ret; + + console_list_lock(); + ret = console_is_registered_locked(con); + console_list_unlock(); + return ret; +} + +/** + * for_each_console_srcu() - Iterator over registered consoles + * @con: struct console pointer used as loop cursor + * + * Although SRCU guarantees the console list will be consistent, the + * struct console fields may be updated by other CPUs while iterating. + * + * Requires console_srcu_read_lock to be held. Can be invoked from + * any context. + */ +#define for_each_console_srcu(con) \ + hlist_for_each_entry_srcu(con, &console_list, node, \ + console_srcu_read_lock_is_held()) + +/** + * for_each_console() - Iterator over registered consoles + * @con: struct console pointer used as loop cursor + * + * The console list and the console->flags are immutable while iterating. + * + * Requires console_list_lock to be held. + */ +#define for_each_console(con) \ + lockdep_assert_console_list_lock_held(); \ + hlist_for_each_entry(con, &console_list, node) + +extern int console_set_on_cmdline; +extern struct console *early_console; + +enum con_flush_mode { + CONSOLE_FLUSH_PENDING, + CONSOLE_REPLAY_ALL, +}; + +extern int add_preferred_console(char *name, int idx, char *options); +extern void console_force_preferred_locked(struct console *con); +extern void register_console(struct console *); +extern int unregister_console(struct console *); +extern void console_lock(void); +extern int console_trylock(void); +extern void console_unlock(void); +extern void console_conditional_schedule(void); +extern void console_unblank(void); +extern void console_flush_on_panic(enum con_flush_mode mode); +extern struct tty_driver *console_device(int *); +extern void console_stop(struct console *); +extern void console_start(struct console *); +extern int is_console_locked(void); +extern int braille_register_console(struct console *, int index, + char *console_options, char *braille_options); +extern int braille_unregister_console(struct console *); +#ifdef CONFIG_TTY +extern void console_sysfs_notify(void); +#else +static inline void console_sysfs_notify(void) +{ } +#endif +extern bool console_suspend_enabled; + +/* Suspend and resume console messages over PM events */ +extern void suspend_console(void); +extern void resume_console(void); + +int mda_console_init(void); + +void vcs_make_sysfs(int index); +void vcs_remove_sysfs(int index); + +/* Some debug stub to catch some of the obvious races in the VT code */ +#define WARN_CONSOLE_UNLOCKED() \ + WARN_ON(!atomic_read(&ignore_console_lock_warning) && \ + !is_console_locked() && !oops_in_progress) +/* + * Increment ignore_console_lock_warning if you need to quiet + * WARN_CONSOLE_UNLOCKED() for debugging purposes. + */ +extern atomic_t ignore_console_lock_warning; + +/* VESA Blanking Levels */ +#define VESA_NO_BLANKING 0 +#define VESA_VSYNC_SUSPEND 1 +#define VESA_HSYNC_SUSPEND 2 +#define VESA_POWERDOWN 3 + +extern void console_init(void); + +/* For deferred console takeover */ +void dummycon_register_output_notifier(struct notifier_block *nb); +void dummycon_unregister_output_notifier(struct notifier_block *nb); + +#endif /* _LINUX_CONSOLE_H */ |