Corstone700: add support for mhuv2 in arm TF-A

Note: This patch implements in-band messaging protocol only.
ARM has launched a next version of MHU i.e. MHUv2 with its latest
subsystems. The main change is that the MHUv2 is now a distributed IP
with different peripheral views (registers) for the sender and receiver.

Another main difference is that MHUv1 duplex channels are now split into
simplex/half duplex in MHUv2. MHUv2 has a configurable number of
communication channels. There is a capability register (MSG_NO_CAP) to
find out how many channels are available in a system.

The register offsets have also changed for STAT, SET & CLEAR registers
from 0x0, 0x8 & 0x10 in MHUv1 to 0x0, 0xC & 0x8 in MHUv2 respectively.

0x0    0x4  0x8  0xC             0x1F
------------------------....-----
| STAT |    |    | SET |    |   |
------------------------....-----
      Transmit Channel

0x0    0x4  0x8   0xC            0x1F
------------------------....-----
| STAT |    | CLR |    |    |   |
------------------------....-----
        Receive Channel

The MHU controller can request the receiver to wake-up and once the
request is removed, the receiver may go back to sleep, but the MHU
itself does not actively put a receiver to sleep.

So, in order to wake-up the receiver when the sender wants to send data,
the sender has to set ACCESS_REQUEST register first in order to wake-up
receiver, state of which can be detected using ACCESS_READY register.
ACCESS_REQUEST has an offset of 0xF88 & ACCESS_READY has an offset
of 0xF8C and are accessible only on any sender channel.

This patch adds necessary changes in a new file required to support the
latest MHUv2 controller. This patch also needs an update in DT binding
for ARM MHUv2 as we need a second register base (tx base) which would
be used as the send channel base.

Change-Id: I1455e08b3d88671a191c558790c503eabe07a8e6
Signed-off-by: Tushar Khandelwal <tushar.khandelwal@arm.com>
diff --git a/plat/arm/board/corstone700/platform.mk b/plat/arm/board/corstone700/platform.mk
index bff3589..a4d4f22 100644
--- a/plat/arm/board/corstone700/platform.mk
+++ b/plat/arm/board/corstone700/platform.mk
@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2019, Arm Limited and Contributors. All rights reserved.
+# Copyright (c) 2019-2020, Arm Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -11,16 +11,19 @@
 				plat/arm/common/arm_common.c	\
 				lib/xlat_tables/aarch32/xlat_tables.c	\
 				lib/xlat_tables/xlat_tables_common.c	\
-				${CORSTONE700_CPU_LIBS}
+				${CORSTONE700_CPU_LIBS}	\
+				plat/arm/board/corstone700/drivers/mhu/mhu.c
 
-PLAT_INCLUDES		:=	-Iplat/arm/board/corstone700/include
+PLAT_INCLUDES		:=	-Iplat/arm/board/corstone700/include	\
+				-Iinclude/plat/arm/common	\
+				-Iplat/arm/board/corstone700/drivers/mhu
 
 NEED_BL32		:=	yes
 
-CORSTONE700_GIC_SOURCES      :=	drivers/arm/gic/common/gic_common.c     \
-				drivers/arm/gic/v2/gicv2_main.c         \
-				drivers/arm/gic/v2/gicv2_helpers.c      \
-				plat/common/plat_gicv2.c                \
+CORSTONE700_GIC_SOURCES	:=	drivers/arm/gic/common/gic_common.c	\
+				drivers/arm/gic/v2/gicv2_main.c		\
+				drivers/arm/gic/v2/gicv2_helpers.c	\
+				plat/common/plat_gicv2.c		\
 				plat/arm/common/arm_gicv2.c
 
 # BL1/BL2 Image not a part of the capsule Image for Corstone700