2 files changed, 54 insertions, 0 deletions

diff --git a/Documentation/input/notifier.txt b/Documentation/input/notifier.txt
new file mode 100644
index 000000000000..95172ca6f3d2
--- /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.
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 622f7849edb9..650b0d8aa89b 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -732,6 +732,8 @@ and is between 256 and 4096 characters. It is defined in the file
                              (Don't attempt to blink the leds)
         i8042.noaux     [HW] Don't check for auxiliary (== mouse) port
         i8042.nokbd     [HW] Don't check/create keyboard port
+        i8042.noloop    [HW] Disable the AUX Loopback command while probing
+                             for the AUX port
         i8042.nomux     [HW] Don't check presence of an active multiplexing
                              controller
         i8042.nopnp     [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX