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/*
* 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 */
struct screen_info;
#ifdef CONFIG_VGA_CONSOLE
void vgacon_register_screen(struct screen_info *si);
#else
static inline void vgacon_register_screen(struct screen_info *si) { }
#endif
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.
* @CON_NBCON: Console can operate outside of the legacy style console_lock
* constraints.
*/
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),
CON_NBCON = BIT(8),
};
/**
* struct nbcon_state - console state for nbcon consoles
* @atom: Compound of the state fields for atomic operations
*
* @req_prio: The priority of a handover request
* @prio: The priority of the current owner
* @unsafe: Console is busy in a non takeover region
* @unsafe_takeover: A hostile takeover in an unsafe state happened in the
* past. The console cannot be safe until re-initialized.
* @cpu: The CPU on which the owner runs
*
* To be used for reading and preparing of the value stored in the nbcon
* state variable @console::nbcon_state.
*
* The @prio and @req_prio fields are particularly important to allow
* spin-waiting to timeout and give up without the risk of a waiter being
* assigned the lock after giving up.
*/
struct nbcon_state {
union {
unsigned int atom;
struct {
unsigned int prio : 2;
unsigned int req_prio : 2;
unsigned int unsafe : 1;
unsigned int unsafe_takeover : 1;
unsigned int cpu : 24;
};
};
};
/*
* The nbcon_state struct is used to easily create and interpret values that
* are stored in the @console::nbcon_state variable. Ensure this struct stays
* within the size boundaries of the atomic variable's underlying type in
* order to avoid any accidental truncation.
*/
static_assert(sizeof(struct nbcon_state) <= sizeof(int));
/**
* nbcon_prio - console owner priority for nbcon consoles
* @NBCON_PRIO_NONE: Unused
* @NBCON_PRIO_NORMAL: Normal (non-emergency) usage
* @NBCON_PRIO_EMERGENCY: Emergency output (WARN/OOPS...)
* @NBCON_PRIO_PANIC: Panic output
* @NBCON_PRIO_MAX: The number of priority levels
*
* A higher priority context can takeover the console when it is
* in the safe state. The final attempt to flush consoles in panic()
* can be allowed to do so even in an unsafe state (Hope and pray).
*/
enum nbcon_prio {
NBCON_PRIO_NONE = 0,
NBCON_PRIO_NORMAL,
NBCON_PRIO_EMERGENCY,
NBCON_PRIO_PANIC,
NBCON_PRIO_MAX,
};
struct console;
struct printk_buffers;
/**
* struct nbcon_context - Context for console acquire/release
* @console: The associated console
* @spinwait_max_us: Limit for spin-wait acquire
* @prio: Priority of the context
* @allow_unsafe_takeover: Allow performing takeover even if unsafe. Can
* be used only with NBCON_PRIO_PANIC @prio. It
* might cause a system freeze when the console
* is used later.
* @backlog: Ringbuffer has pending records
* @pbufs: Pointer to the text buffer for this context
* @seq: The sequence number to print for this context
*/
struct nbcon_context {
/* members set by caller */
struct console *console;
unsigned int spinwait_max_us;
enum nbcon_prio prio;
unsigned int allow_unsafe_takeover : 1;
/* members set by emit */
unsigned int backlog : 1;
/* members set by acquire */
struct printk_buffers *pbufs;
u64 seq;
};
/**
* struct nbcon_write_context - Context handed to the nbcon write callbacks
* @ctxt: The core console context
* @outbuf: Pointer to the text buffer for output
* @len: Length to write
* @unsafe_takeover: If a hostile takeover in an unsafe state has occurred
*/
struct nbcon_write_context {
struct nbcon_context __private ctxt;
char *outbuf;
unsigned int len;
bool unsafe_takeover;
};
/**
* 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
*
* @write_atomic: Write callback for atomic context
* @nbcon_state: State for nbcon consoles
* @nbcon_seq: Sequence number of the next record for nbcon to print
* @pbufs: Pointer to nbcon private buffer
*/
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;
/* nbcon console specific members */
bool (*write_atomic)(struct console *con,
struct nbcon_write_context *wctxt);
atomic_t __private nbcon_state;
atomic_long_t __private nbcon_seq;
struct printk_buffers *pbufs;
};
#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)
#ifdef CONFIG_PRINTK
extern bool nbcon_can_proceed(struct nbcon_write_context *wctxt);
extern bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt);
extern bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt);
#else
static inline bool nbcon_can_proceed(struct nbcon_write_context *wctxt) { return false; }
static inline bool nbcon_enter_unsafe(struct nbcon_write_context *wctxt) { return false; }
static inline bool nbcon_exit_unsafe(struct nbcon_write_context *wctxt) { return false; }
#endif
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(const char *name, const short 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 */