aboutsummaryrefslogtreecommitdiff
path: root/Documentation
diff options
context:
space:
mode:
authorSamuel Thibault <samuel.thibault@ens-lyon.org>2008-03-10 03:08:45 -0700
committerDmitry Torokhov <dmitry.torokhov@gmail.com>2008-03-14 11:54:19 -0400
commite32f7ee876ebbdec73e4c19dce559a20c2ab840e (patch)
treee1b70d801f7a5cafdd3af2cbf11c87bb2d6843a5 /Documentation
parent05be5fc4c75fd91c9601b5e697f94112f0f6482b (diff)
downloadlinux-e32f7ee876ebbdec73e4c19dce559a20c2ab840e.tar.gz
Input: add keyboard notifier documentation
Document the keyboard notifier. Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz> SIgned-off-by: Dmitry Torokhov <dtor@mail.ru>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/input/notifier.txt52
1 files changed, 52 insertions, 0 deletions
diff --git a/Documentation/input/notifier.txt b/Documentation/input/notifier.txt
new file mode 100644
index 00000000000..95172ca6f3d
--- /dev/null
+++ b/Documentation/input/notifier.txt
@@ -0,0 +1,52 @@
+Keyboard notifier
+
+One can use register_keyboard_notifier to get called back on keyboard
+events (see kbd_keycode() function for details). The passed structure is
+keyboard_notifier_param:
+
+- 'vc' always provide the VC for which the keyboard event applies;
+- 'down' is 1 for a key press event, 0 for a key release;
+- 'shift' is the current modifier state, mask bit indexes are KG_*;
+- 'value' depends on the type of event.
+
+- KBD_KEYCODE events are always sent before other events, value is the keycode.
+- KBD_UNBOUND_KEYCODE events are sent if the keycode is not bound to a keysym.
+ value is the keycode.
+- KBD_UNICODE events are sent if the keycode -> keysym translation produced a
+ unicode character. value is the unicode value.
+- KBD_KEYSYM events are sent if the keycode -> keysym translation produced a
+ non-unicode character. value is the keysym.
+- KBD_POST_KEYSYM events are sent after the treatment of non-unicode keysyms.
+ That permits one to inspect the resulting LEDs for instance.
+
+For each kind of event but the last, the callback may return NOTIFY_STOP in
+order to "eat" the event: the notify loop is stopped and the keyboard event is
+dropped.
+
+In a rough C snippet, we have:
+
+kbd_keycode(keycode) {
+ ...
+ params.value = keycode;
+ if (notifier_call_chain(KBD_KEYCODE,&params) == NOTIFY_STOP)
+ || !bound) {
+ notifier_call_chain(KBD_UNBOUND_KEYCODE,&params);
+ return;
+ }
+
+ if (unicode) {
+ param.value = unicode;
+ if (notifier_call_chain(KBD_UNICODE,&params) == NOTIFY_STOP)
+ return;
+ emit unicode;
+ return;
+ }
+
+ params.value = keysym;
+ if (notifier_call_chain(KBD_KEYSYM,&params) == NOTIFY_STOP)
+ return;
+ apply keysym;
+ notifier_call_chain(KBD_POST_KEYSYM,&params);
+}
+
+NOTE: This notifier is usually called from interrupt context.