[media] rc-core support for Microsoft IR keyboard/mouse

This is a custom IR protocol decoder, for the RC-6-ish protocol used by
the Microsoft Remote Keyboard, apparently developed internally at
Microsoft, and officially dubbed MCIR-2, per their March 2011 remote and
transceiver requirements and specifications document, which also touches
on this IR keyboard/mouse device.

Its a standard keyboard with embedded thumb stick mouse pointer and
mouse buttons, along with a number of media keys. The media keys are
standard RC-6, identical to the signals from the stock MCE remotes, and
will be handled as such. The keyboard and mouse signals will be decoded
and delivered to the system by an input device registered specifically
by this driver.

Successfully tested with multiple mceusb-driven transceivers, as well as
with fintek-cir and redrat3 hardware. Essentially, any raw IR hardware
with enough sampling resolution should be able to use this decoder,
nothing about it is at all receiver-hardware-specific.

This work is inspired by lirc_mod_mce:

The documentation there and code aided in understanding and decoding the
protocol, but the bulk of the code is actually borrowed more from the
existing in-kernel decoders than anything. I did recycle the keyboard
keycode table, a few defines, and some of the keyboard and mouse data
parsing bits from lirc_mod_mce though.

Special thanks to James Meyer for providing the hardware, and being
patient with me as I took forever to get around to writing this.

callback routine to ensure we don't get any stuck keys, and used
symbolic names for the keytable. Also cc'ing Florian this time, who I
believe is the original mod-mce author...

CC: Florian Demski <fdemski@users.sourceforge.net>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/rc/Kconfig

@@ -87,6 +87,17 @@ config IR_RC5_SZ_DECODER
 	   uses an IR protocol that is almost standard RC-5, but not quite,
 	   as it uses an additional bit).
 
+config IR_MCE_KBD_DECODER
+	tristate "Enable IR raw decoder for the MCE keyboard/mouse protocol"
+	depends on RC_CORE
+	select BITREVERSE
+	default y
+
+	---help---
+	   Enable this option if you have a Microsoft Remote Keyboard for
+	   Windows Media Center Edition, which you would like to use with
+	   a raw IR receiver in your system.
+
 config IR_LIRC_CODEC
 	tristate "Enable IR to LIRC bridge"
 	depends on RC_CORE

drivers/media/rc/Makefile

@@ -10,6 +10,7 @@ obj-$(CONFIG_IR_RC6_DECODER) += ir-rc6-decoder.o
 obj-$(CONFIG_IR_JVC_DECODER) += ir-jvc-decoder.o
 obj-$(CONFIG_IR_SONY_DECODER) += ir-sony-decoder.o
 obj-$(CONFIG_IR_RC5_SZ_DECODER) += ir-rc5-sz-decoder.o
+obj-$(CONFIG_IR_MCE_KBD_DECODER) += ir-mce_kbd-decoder.o
 obj-$(CONFIG_IR_LIRC_CODEC) += ir-lirc-codec.o
 
 # stand-alone IR receivers/transmitters