vt,console,kdb: implement atomic console enter/leave functions

These functions allow the kernel debugger to save and restore the
state of the system console.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
CC: David Airlie <airlied@linux.ie>
CC: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/linux/console.h b/include/linux/console.h
index dcca5339ceb3..f76fc297322d 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -55,6 +55,16 @@ struct consw {
         void    (*con_invert_region)(struct vc_data *, u16 *, int);
         u16    *(*con_screen_pos)(struct vc_data *, int);
         unsigned long (*con_getxy)(struct vc_data *, unsigned long, int *, int *);
+        /*
+         * 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 *);
+        /*
+         * Restore the console to its pre-debug state as closely as possible.
+         */
+        int     (*con_debug_leave)(struct vc_data *);
 };
 
 extern const struct consw *conswitchp;
@@ -69,6 +79,9 @@ int register_con_driver(const struct consw *csw, int first, int last);
 int unregister_con_driver(const struct consw *csw);
 int take_over_console(const struct consw *sw, int first, int last, int deflt);
 void give_up_console(const struct consw *sw);
+int con_debug_enter(struct vc_data *vc);
+int con_debug_leave(void);
+
 /* scroll */
 #define SM_UP       (1)
 #define SM_DOWN     (2)