input: keychord: Add keychord driver

This driver allows userspace to receive notification when client
specified key combinations are pressed.
The client opens /dev/keychord and writes a list of keychords
for the driver to monitor.
The client then reads or polls /dev/keychord for notifications.
A client specified ID for the keychord is returned from read()
when a keychord press is detected.

Signed-off-by: Mike Lockwood <lockwood@android.com>

keychord: fix to build without CONFIG_PREEMPT

Change-Id: I911f13aeda4224b6fa57863bc7e8972fec8837fb
diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 748a193..6f4ad1a 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -193,6 +193,17 @@
 	  To compile this driver as a module, choose M here: the module will be
 	  called ati_remote2.
 
+config INPUT_KEYCHORD
+	tristate "Key chord input driver support"
+	help
+	  Say Y here if you want to enable the key chord driver
+	  accessible at /dev/keychord.  This driver can be used
+	  for receiving notifications when client specified key
+	  combinations are pressed.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called keychord.
+
 config INPUT_KEYSPAN_REMOTE
 	tristate "Keyspan DMR USB remote control (EXPERIMENTAL)"
 	depends on EXPERIMENTAL