Console events and accessibility

Some external modules like Speakup need to monitor console output.

This adds a VT notifier that such modules can use to get console output events:
allocation, deallocation, writes, other updates (cursor position, switch, etc.)

[akpm@linux-foundation.org: fix headers_check]
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 18 insertions, 0 deletions

diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index 6ec7e21a3699..0c40cc0b4a36 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -242,5 +242,11 @@ static inline int notifier_to_errno(int ret)
 
 extern struct blocking_notifier_head reboot_notifier_list;
 
+/* Virtual Terminal events. */
+#define VT_ALLOCATE             0x0001 /* Console got allocated */
+#define VT_DEALLOCATE           0x0002 /* Console will be deallocated */
+#define VT_WRITE                0x0003 /* A char got output */
+#define VT_UPDATE               0x0004 /* A bigger update occurred */
+
 #endif /* __KERNEL__ */
 #endif /* _LINUX_NOTIFIER_H */
diff --git a/include/linux/vt.h b/include/linux/vt.h
index ba806e8711be..02c1c0288770 100644
--- a/include/linux/vt.h
+++ b/include/linux/vt.h
@@ -1,6 +1,18 @@
 #ifndef _LINUX_VT_H
 #define _LINUX_VT_H
 
+#ifdef __KERNEL__
+struct notifier_block;
+
+struct vt_notifier_param {
+        struct vc_data *vc;     /* VC on which the update happened */
+        unsigned int c;         /* Printed char */
+};
+
+extern int register_vt_notifier(struct notifier_block *nb);
+extern int unregister_vt_notifier(struct notifier_block *nb);
+#endif
+
 /*
  * These constants are also useful for user-level apps (e.g., VC
  * resizing).