LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
To: torvalds@osdl.org, linux-input@vger.kernel.org, dtor@mail.ru
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH2] keyboard notifier documentation
Date: Sat, 9 Feb 2008 11:44:05 +0000	[thread overview]
Message-ID: <20080209114405.GD4379@implementation> (raw)
In-Reply-To: <20080209013322.GC4463@implementation>

Document the keyboard notifier.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

--- /dev/null	2008-02-09 01:22:34.790011677 +0000
+++ linux/Documentation/input/notifier.txt	2008-02-09 01:28:12.000000000 +0000
@@ -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.

      parent reply	other threads:[~2008-02-09 11:44 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-09  1:33 [PATCH] " Samuel Thibault
2008-02-09  4:12 ` Randy Dunlap
2008-02-09 11:40   ` Samuel Thibault
2008-02-09 15:38     ` Randy Dunlap
2008-02-09 15:43       ` Samuel Thibault
2008-02-09 11:44 ` Samuel Thibault [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20080209114405.GD4379@implementation \
    --to=samuel.thibault@ens-lyon.org \
    --cc=dtor@mail.ru \
    --cc=linux-input@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=torvalds@osdl.org \
    --subject='Re: [PATCH2] keyboard notifier documentation' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).