Add basic MHU drivers

Add MHUv2 doorbell driver implementation
Add MHU doorbell driver for Juno board
Add a dummy MHU driver
Add some comments to the mailbox header file

Change-Id: I0950a7ca3afeec88ca691ca2486022dfbb3319b8

13 files changed, 715 insertions, 7 deletions

diff --git a/applications/message_process/CMakeLists.txt b/applications/message_process/CMakeLists.txt
index 9c80672..2f7e5cf 100644
--- a/applications/message_process/CMakeLists.txt
+++ b/applications/message_process/CMakeLists.txt
@@ -18,4 +18,4 @@
 
 add_library(message_process STATIC src/message_process.cc)
 target_include_directories(message_process PUBLIC include ${LINUX_DRIVER_STACK_PATH}/kernel)
-target_link_libraries(message_process PRIVATE cmsis_core inference_process mailbox)
+target_link_libraries(message_process PRIVATE cmsis_core inference_process ethosu_mailbox)
diff --git a/drivers/CMakeLists.txt b/drivers/CMakeLists.txt
index cea6325..c130a26 100644
--- a/drivers/CMakeLists.txt
+++ b/drivers/CMakeLists.txt
@@ -20,4 +20,13 @@ add_library(ethosu_drivers INTERFACE)
 
 # Mailbox driver
 add_subdirectory(mailbox)
-target_link_libraries(ethosu_drivers INTERFACE mailbox)
+target_link_libraries(ethosu_drivers INTERFACE ethosu_mailbox)
+
+# MHU drivers
+add_subdirectory(mhu_v2)
+add_subdirectory(mhu_juno)
+add_subdirectory(mhu_dummy)
+target_link_libraries(ethosu_drivers INTERFACE ethosu_mhu_v2)
+target_link_libraries(ethosu_drivers INTERFACE ethosu_mhu_juno)
+target_link_libraries(ethosu_drivers INTERFACE ethosu_mhu_dummy)
+
diff --git a/drivers/mailbox/CMakeLists.txt b/drivers/mailbox/CMakeLists.txt
index 6d55407..bd2dae3 100644
--- a/drivers/mailbox/CMakeLists.txt
+++ b/drivers/mailbox/CMakeLists.txt
@@ -16,7 +16,6 @@
 # limitations under the License.
 #
 
-add_library(mailbox STATIC)
-target_include_directories(mailbox PUBLIC include)
-target_sources(mailbox PRIVATE src/mailbox.cc)
-
+add_library(ethosu_mailbox STATIC)
+target_include_directories(ethosu_mailbox PUBLIC include)
+target_sources(ethosu_mailbox PRIVATE src/mailbox.cc)
diff --git a/drivers/mailbox/include/mailbox.hpp b/drivers/mailbox/include/mailbox.hpp
index 465503e..f3a2dc4 100644
--- a/drivers/mailbox/include/mailbox.hpp
+++ b/drivers/mailbox/include/mailbox.hpp
@@ -25,19 +25,63 @@
 
 namespace Mailbox {
 
+/**
+ * The Mailbox parent class
+ *
+ * Intended to be implemented by a driver subclass, see MHU_v2 driver as example.
+ */
 class Mailbox {
 public:
+    /**
+     * Constructor/Destructor
+     */
     Mailbox();
     virtual ~Mailbox();
-    virtual bool sendMessage()   = 0;
+
+    /**
+     * Intended to trigger an interrupt to an external block
+     * MUST be implemented by subclass.
+     */
+    virtual bool sendMessage() = 0;
+
+    /**
+     * Intended to be called when Cortex M has received an
+     * interrupt/event from mailbox/mhu. If an interrupt needs to be cleared,
+     * this is a good place to do that. MUST call notify().
+     * MUST be implemented by subclass.
+     */
     virtual void handleMessage() = 0;
+
+    /**
+     * Can be used to verify that hardware versions match expected versions
+     * CAN be implemented by subclass, optional. Default impl returns true.
+     */
     virtual bool verifyHardware();
+
+    /**
+     * Function signature for callbacks
+     */
     typedef void (*CallbackFptr)(void *userArg);
+
+    /**
+     * Register a callback to be called when a message is received.
+     */
     void registerCallback(CallbackFptr callback, void *userArg);
+
+    /**
+     * Remove a specific callback from the callback list.
+     */
     void deregisterCallback(CallbackFptr callback, void *userArg);
 
 protected:
+    /**
+     * Calls every registered callback when a message has been received.
+     */
     void notify();
+
+    /**
+     * Helper functions
+     */
     uint32_t read32(volatile uint32_t *baseAddr, const uint32_t offset);
     void write32(volatile uint32_t *baseAddr, const uint32_t offset, const uint32_t value);
 
diff --git a/drivers/mhu_dummy/CMakeLists.txt b/drivers/mhu_dummy/CMakeLists.txt
new file mode 100644
index 0000000..83943d6
--- /dev/null
+++ b/drivers/mhu_dummy/CMakeLists.txt
@@ -0,0 +1,23 @@
+#
+# Copyright (c) 2020 Arm Limited. All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the License); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an AS IS BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+add_library(ethosu_mhu_dummy STATIC)
+target_include_directories(ethosu_mhu_dummy PUBLIC include)
+
+target_sources(ethosu_mhu_dummy PRIVATE src/mhu_dummy.cc)
+target_link_libraries(ethosu_mhu_dummy PRIVATE ethosu_mailbox)
diff --git a/drivers/mhu_dummy/include/mhu_dummy.hpp b/drivers/mhu_dummy/include/mhu_dummy.hpp
new file mode 100644
index 0000000..365f392
--- /dev/null
+++ b/drivers/mhu_dummy/include/mhu_dummy.hpp
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2020 Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef MHU_DUMMY_HPP
+#define MHU_DUMMY_HPP
+
+#include <mailbox.hpp>
+
+namespace Mailbox {
+
+class MHUDummy : public Mailbox {
+public:
+    MHUDummy();
+    virtual ~MHUDummy();
+    virtual bool sendMessage() final;
+    virtual void handleMessage() final;
+};
+
+} // namespace Mailbox
+
+#endif /* #ifndef MHU_DUMMY_HPP */
diff --git a/drivers/mhu_dummy/src/mhu_dummy.cc b/drivers/mhu_dummy/src/mhu_dummy.cc
new file mode 100644
index 0000000..196fb93
--- /dev/null
+++ b/drivers/mhu_dummy/src/mhu_dummy.cc
@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2020 Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <mhu_dummy.hpp>
+
+namespace Mailbox {
+
+MHUDummy::MHUDummy() {}
+MHUDummy::~MHUDummy() {}
+
+void MHUDummy::handleMessage() {
+    notify();
+}
+bool MHUDummy::sendMessage() {
+    return true;
+}
+
+} // namespace Mailbox
diff --git a/drivers/mhu_juno/CMakeLists.txt b/drivers/mhu_juno/CMakeLists.txt
new file mode 100644
index 0000000..1dbb6fd
--- /dev/null
+++ b/drivers/mhu_juno/CMakeLists.txt
@@ -0,0 +1,23 @@
+#
+# Copyright (c) 2020 Arm Limited. All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the License); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an AS IS BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+add_library(ethosu_mhu_juno STATIC)
+target_include_directories(ethosu_mhu_juno PUBLIC include)
+
+target_sources(ethosu_mhu_juno PRIVATE src/mhu_juno.cc)
+target_link_libraries(ethosu_mhu_juno PRIVATE ethosu_mailbox)
diff --git a/drivers/mhu_juno/include/mhu_juno.hpp b/drivers/mhu_juno/include/mhu_juno.hpp
new file mode 100644
index 0000000..f864cd5
--- /dev/null
+++ b/drivers/mhu_juno/include/mhu_juno.hpp
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2020 Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef MHU_JUNO_HPP
+#define MHU_JUNO_HPP
+
+#include <mailbox.hpp>
+
+#include <cstddef>
+#include <cstdint>
+
+namespace Mailbox {
+
+// Doorbell implementation only
+class MHUJuno : public Mailbox {
+public:
+    MHUJuno(const uint32_t baseAddress);
+    virtual ~MHUJuno();
+    virtual bool sendMessage() final;
+    virtual void handleMessage() final;
+    virtual bool verifyHardware() final;
+
+private:
+    /* Offsets */
+    static constexpr uint32_t CPU0_INTR_STAT = 0x00;
+    static constexpr uint32_t CPU0_INTR_SET  = 0x04;
+    static constexpr uint32_t CPU0_INTR_CLR  = 0x08;
+    static constexpr uint32_t CPU1_INTR_STAT = 0x10;
+    static constexpr uint32_t CPU1_INTR_SET  = 0x14;
+    static constexpr uint32_t CPU1_INTR_CLR  = 0x18;
+    static constexpr uint32_t OFFSET         = 0x10;
+    static constexpr uint32_t PIDR0          = 0xfe0;
+    static constexpr uint32_t PIDR1          = 0xfe4;
+    static constexpr uint32_t PIDR2          = 0xfe8;
+    static constexpr uint32_t PIDR3          = 0xfec;
+    static constexpr uint32_t PIDR4          = 0xfd0;
+    static constexpr uint32_t CIDR0          = 0xff0;
+    static constexpr uint32_t CIDR1          = 0xff4;
+    static constexpr uint32_t CIDR2          = 0xff8;
+    static constexpr uint32_t CIDR3          = 0xffc;
+
+    volatile uint32_t *baseAddr;
+
+    void clearMessage();
+    void write(uint32_t offset, uint32_t val);
+    uint32_t read(uint32_t offset);
+};
+
+} // namespace Mailbox
+
+#endif /* #ifndef MHU_JUNO_HPP */
diff --git a/drivers/mhu_juno/src/mhu_juno.cc b/drivers/mhu_juno/src/mhu_juno.cc
new file mode 100644
index 0000000..9a58a80
--- /dev/null
+++ b/drivers/mhu_juno/src/mhu_juno.cc
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2020 Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <mhu_juno.hpp>
+
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+#include <cstring>
+
+namespace Mailbox {
+
+MHUJuno::MHUJuno(const uint32_t baseAddress) {
+    baseAddr = reinterpret_cast<volatile uint32_t *>(baseAddress);
+}
+
+void MHUJuno::handleMessage() {
+    clearMessage();
+    notify();
+}
+
+MHUJuno::~MHUJuno() {}
+
+// Doorbell only
+bool MHUJuno::sendMessage() {
+    write(CPU1_INTR_SET, 1);
+    return true;
+}
+// Doorbell only
+void MHUJuno::clearMessage() {
+    write(CPU0_INTR_CLR, 0xF);
+}
+
+bool MHUJuno::verifyHardware() {
+    uint32_t pidr0 = read(PIDR0);
+    uint32_t pidr1 = read(PIDR1);
+    uint32_t pidr2 = read(PIDR2);
+    uint32_t pidr3 = read(PIDR3);
+    uint32_t pidr4 = read(PIDR4);
+    uint32_t cidr0 = read(CIDR0);
+    uint32_t cidr1 = read(CIDR1);
+    uint32_t cidr2 = read(CIDR2);
+    uint32_t cidr3 = read(CIDR3);
+
+    if (pidr0 != 0x56 || pidr1 != 0xb8 || pidr2 != 0x0b || pidr3 != 0x00 || pidr4 != 0x04 || cidr0 != 0x0d ||
+        cidr1 != 0xf0 || cidr2 != 0x05 || cidr3 != 0xb1) {
+        return false;
+    }
+    return true;
+}
+
+void MHUJuno::write(const uint32_t offset, const uint32_t value) {
+    write32(baseAddr, offset, value);
+}
+
+uint32_t MHUJuno::read(const uint32_t offset) {
+    return read32(baseAddr, offset);
+}
+
+} // namespace Mailbox
diff --git a/drivers/mhu_v2/CMakeLists.txt b/drivers/mhu_v2/CMakeLists.txt
new file mode 100644
index 0000000..2ecf35a
--- /dev/null
+++ b/drivers/mhu_v2/CMakeLists.txt
@@ -0,0 +1,23 @@
+#
+# Copyright (c) 2020 Arm Limited. All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the License); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an AS IS BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+add_library(ethosu_mhu_v2 STATIC)
+target_include_directories(ethosu_mhu_v2 PUBLIC include)
+
+target_sources(ethosu_mhu_v2 PRIVATE src/mhu_v2.cc)
+target_link_libraries(ethosu_mhu_v2 PRIVATE ethosu_mailbox)
diff --git a/drivers/mhu_v2/include/mhu_v2.hpp b/drivers/mhu_v2/include/mhu_v2.hpp
new file mode 100644
index 0000000..881c0ea
--- /dev/null
+++ b/drivers/mhu_v2/include/mhu_v2.hpp
@@ -0,0 +1,169 @@
+/*
+ * Copyright (c) 2020 Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef MHU_V2_HPP
+#define MHU_V2_HPP
+
+#include <mailbox.hpp>
+
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+#include <cstring>
+
+namespace Mailbox {
+/*
+ * SENDER OVERVIEW
+ * ------------------------------------------------------------------------
+ * Offset       Access Type Register Name                        Short Name
+ * ------------------------------------------------------------------------
+ * 0x000-0xF7C  -           Sender Channel Window 0-123          -
+ * 0xF80        RO          Message Handling Unit Configuration  MHU_CFG
+ * 0xF84        RW          Response Configuration               RESP_CFG
+ * 0xF88        RW          Access Request                       ACCESS_REQUEST
+ * 0xF8C        RO          Access Ready                         ACCESS_READY
+ * 0xF90        RO          Interrupt Status                     INT_ST
+ * 0xF94        WO          Interrupt Clear                      INT_CLR
+ * 0xF98        RW          Interrupt Enable                     INT_EN
+ * 0xF9C-0xFC4  RO          Reserved                             -
+ * 0xFC8        RO          Implementer Identification Register  IIDR
+ * 0xFCC        RO          Architecture Identification Register AIDR
+ * 0xFD0-0xFFC  -           IMPL DEF Identification Regs         -
+ */
+
+/*
+ * RECEIVER OVERVIEW
+ * ------------------------------------------------------------------------
+ * Offset       Access Type Register Name                        Short Name
+ * ------------------------------------------------------------------------
+ * 0x000-0xF7C  -           Receiver Channel Window 0-123        -
+ * 0xF80        RO          Message Handling Unit Configuration  MHU_CFG
+ * 0xF84-0xFC4  RO          Reserved                             -
+ * 0xFC8        RO          Implementer Identification Register  IIDR
+ * 0xFCC        RO          Architecture Identification Register AIDR
+ * 0xFD0-0xFFC  -           IMPL DEF Identification Regs         -
+ */
+
+/*
+ * Sender Channel Window
+ * ------------------------------------------------------------------------
+ * Offset       Access Type Register Name                        Short Name
+ * ------------------------------------------------------------------------
+ * 0x00         RO          Channel Status                       CH_ST
+ * 0x04         RO          Reserved                             -
+ * 0x08         RO          Reserved                             -
+ * 0x0C         WO          Channel Set                          CH_SET
+ * 0x10         RO          Reserved                             -
+ * 0x14         RO          Reserved                             -
+ * 0x18         RO          Reserved                             -
+ * 0x1C         RO          Reserved                             -
+ */
+
+/*
+ * Receiver Channel Window
+ * ------------------------------------------------------------------------
+ * Offset       Access Type Register Name                        Short Name
+ * ------------------------------------------------------------------------
+ * 0x00         RO          Channel Status                       CH_ST
+ * 0x04         RO          Channel Status Masked                CH_ST_MSK
+ * 0x08         WO          Channel Clear                        CH_CLR
+ * 0x0C         RO          Reserved                             -
+ * 0x10         RO          Channel Mask Status                  CH_MSK_ST
+ * 0x14         WO          Channel Mask Set                     CH_MSK_SET
+ * 0x18         WO          Channel Mask Clear                   CH_MSK_CLR
+ * 0x1C         RO          Reserved                             -
+ */
+
+// Doorbell implementation only
+// NOTE: MHUv2 is unidirectional. Two MHU's are needed for bidirectional
+//       messaging. txBase/rxBase refers to the base address of _two_
+//       separate MHU blocks.
+class MHUv2 : public Mailbox {
+public:
+    MHUv2(const uint32_t txBaseAddress, const uint32_t rxBaseAddress);
+    virtual ~MHUv2();
+    virtual bool sendMessage() final;
+    virtual void handleMessage() final;
+    virtual bool verifyHardware() final;
+
+private:
+    /* Offsets */
+    static constexpr uint32_t MHUv2_CH_ST                   = 0x00;
+    static constexpr uint32_t MHUv2_CH_ST_MSK               = 0x04;
+    static constexpr uint32_t MHUv2_CH_CLR                  = 0x08;
+    static constexpr uint32_t MHUv2_CH_SET                  = 0x0C;
+    static constexpr uint32_t MHUv2_CH_MSK_ST               = 0x10;
+    static constexpr uint32_t MHUv2_CH_MSK_SET              = 0x14;
+    static constexpr uint32_t MHUv2_CH_MSK_CLR              = 0x18;
+    static constexpr uint32_t MHUv2_CH_INT_CLR              = 0x14;
+    static constexpr uint32_t MHUv2_CH_INT_EN               = 0x18;
+    static constexpr uint32_t MHUv2_SND_CHAN_WINDOW_SIZE    = 0x20;
+    static constexpr uint32_t MHUv2_SND_MHU_CFG_OFFS        = 0xF80;
+    static constexpr uint32_t MHUv2_SND_RESP_CFG_OFFS       = 0xF84;
+    static constexpr uint32_t MHUv2_SND_ACCESS_REQUEST_OFFS = 0xF88;
+    static constexpr uint32_t MHUv2_SND_ACCESS_READY_OFFS   = 0xF8C;
+    static constexpr uint32_t MHUv2_SND_INT_ST_OFFS         = 0xF90;
+    static constexpr uint32_t MHUv2_SND_INT_CLR_OFFS        = 0xF94;
+    static constexpr uint32_t MHUv2_SND_INT_EN_OFFS         = 0xF98;
+    static constexpr uint32_t MHUv2_SND_IIDR_OFFS           = 0xFC8;
+    static constexpr uint32_t MHUv2_SND_AIDR_OFFS           = 0xFCC;
+    static constexpr uint32_t MHUv2_RCV_CHAN_WINDOW_SIZE    = 0x20;
+    static constexpr uint32_t MHUv2_RCV_MHU_CFG_OFFS        = 0xF80;
+    static constexpr uint32_t MHUv2_RCV_IIDR_OFFS           = 0xFC8;
+    static constexpr uint32_t MHUv2_RCV_AIDR_OFFS           = 0xFCC;
+    static constexpr uint32_t MHUv2_RCV_INT_EN_OFFS         = 0xF98;
+
+    struct aidr_t {
+        uint32_t ARCH_MINOR_REV : 4;
+        uint32_t ARCH_MAJOR_REV : 4;
+        uint32_t RESERVED : 24;
+    };
+
+    volatile uint32_t *txBaseAddr;
+    volatile uint32_t *rxBaseAddr;
+
+    void clearMessage();
+    void printAIDR(bool tx = true, bool rx = true);
+
+    void txWrite(uint32_t offset, uint32_t value);
+    void rxWrite(uint32_t offset, uint32_t value);
+    uint32_t txRead(uint32_t offset);
+    uint32_t rxRead(uint32_t offset);
+
+    // Sender/tx
+    uint32_t getAccessReady();
+    uint32_t getAccessRequest();
+    uint32_t getInterruptStatus();
+    uint32_t getTxAIDR();
+    uint32_t getTxStatusForChan(uint8_t chan);
+    void enableAccessRequest();
+    void disableAccessRequest();
+    void setCombinedClearInterrupt(bool enable);
+    void setReadyNotReadyInterrupts(bool enable);
+
+    // Receiver/rx
+    uint32_t getRxAIDR();
+    uint32_t getRxStatusForChan(uint8_t chan);
+    void setCombinedRecvInterrupt(bool enable);
+    void enableClearChanInterrupt(uint8_t chan);
+    void disableClearChanInterrupt(uint8_t chan);
+};
+
+} // namespace Mailbox
+
+#endif /* #ifndef MHU_V2_HPP */
diff --git a/drivers/mhu_v2/src/mhu_v2.cc b/drivers/mhu_v2/src/mhu_v2.cc
new file mode 100644
index 0000000..76336ce
--- /dev/null
+++ b/drivers/mhu_v2/src/mhu_v2.cc
@@ -0,0 +1,207 @@
+/*
+ * Copyright (c) 2020 Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <mhu_v2.hpp>
+
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+#include <cstring>
+
+namespace Mailbox {
+
+MHUv2::MHUv2(const uint32_t txBaseAddress, const uint32_t rxBaseAddress) :
+    txBaseAddr(reinterpret_cast<volatile uint32_t *>(txBaseAddress)),
+    rxBaseAddr(reinterpret_cast<volatile uint32_t *>(rxBaseAddress)) {
+
+    setCombinedRecvInterrupt(true);
+    enableAccessRequest(); // Set high throughout
+}
+
+void MHUv2::handleMessage() {
+    clearMessage();
+    notify();
+}
+
+MHUv2::~MHUv2() {
+    setCombinedRecvInterrupt(false);
+    disableAccessRequest();
+}
+
+bool MHUv2::verifyHardware() {
+    // Sanity check MHUv2.1 id's (tx/rx)
+    struct aidr_t *a;
+    uint32_t txAIDR = getTxAIDR();
+    uint32_t rxAIDR = getRxAIDR();
+
+    a = reinterpret_cast<struct aidr_t *>(&txAIDR);
+    if (a->ARCH_MAJOR_REV != 1 || a->ARCH_MINOR_REV != 1) {
+        return false;
+    }
+
+    a = reinterpret_cast<struct aidr_t *>(&rxAIDR);
+    if (a->ARCH_MAJOR_REV != 1 || a->ARCH_MINOR_REV != 1) {
+        return false;
+    }
+
+    return true;
+}
+
+uint32_t MHUv2::getTxStatusForChan(uint8_t chan) {
+    assert(chan >= 0);
+    assert(chan < 124);
+    return txRead((chan * MHUv2_SND_CHAN_WINDOW_SIZE) + MHUv2_CH_ST);
+}
+
+uint32_t MHUv2::getRxStatusForChan(uint8_t chan) {
+    assert(chan >= 0);
+    assert(chan < 124);
+    return rxRead((chan * MHUv2_RCV_CHAN_WINDOW_SIZE) + MHUv2_CH_ST);
+}
+
+uint32_t MHUv2::getInterruptStatus() {
+    return txRead(MHUv2_SND_INT_ST_OFFS);
+}
+
+uint32_t MHUv2::getAccessReady() {
+    return txRead(MHUv2_SND_ACCESS_READY_OFFS);
+}
+
+uint32_t MHUv2::getAccessRequest() {
+    return txRead(MHUv2_SND_ACCESS_REQUEST_OFFS);
+}
+
+uint32_t MHUv2::getTxAIDR() {
+    return txRead(MHUv2_SND_AIDR_OFFS);
+}
+
+uint32_t MHUv2::getRxAIDR() {
+    return rxRead(MHUv2_RCV_AIDR_OFFS);
+}
+
+void MHUv2::enableAccessRequest() {
+    txWrite(MHUv2_SND_ACCESS_REQUEST_OFFS, 1);
+}
+
+void MHUv2::disableAccessRequest() {
+    txWrite(MHUv2_SND_ACCESS_REQUEST_OFFS, 0);
+}
+
+/*
+ * MHUv2.1
+ * sender:   combined clear interrupt
+ */
+void MHUv2::setCombinedClearInterrupt(bool enable) {
+    uint32_t val = txRead(MHUv2_SND_INT_EN_OFFS);
+    if (enable) {
+        val |= (1 << 2);
+    } else {
+        val &= ~(1 << 2);
+    }
+    txWrite(MHUv2_SND_INT_EN_OFFS, val);
+}
+
+/*
+ * MHUv2.1
+ * receiver: combined recv interrupt
+ */
+void MHUv2::setCombinedRecvInterrupt(bool enable) {
+    uint32_t val = rxRead(MHUv2_RCV_INT_EN_OFFS);
+    if (enable) {
+        val |= (1 << 2);
+    } else {
+        val &= ~(1 << 2);
+    }
+    rxWrite(MHUv2_SND_INT_EN_OFFS, val);
+}
+
+// Enable/disable R2NR/NR2R interrupts
+void MHUv2::setReadyNotReadyInterrupts(bool enable) {
+    uint32_t val = txRead(MHUv2_SND_INT_EN_OFFS);
+    if (enable) {
+        val |= (1 << 0 | 1 << 1);
+    } else {
+        val &= ~(1 << 0 | 1 << 1);
+    }
+    txWrite(MHUv2_SND_INT_EN_OFFS, val);
+}
+
+void MHUv2::enableClearChanInterrupt(uint8_t chan) {
+    assert(chan >= 0);
+    assert(chan < 124);
+    txWrite((chan * MHUv2_SND_CHAN_WINDOW_SIZE) + MHUv2_CH_INT_EN, 1);
+}
+
+void MHUv2::disableClearChanInterrupt(uint8_t chan) {
+    assert(chan >= 0);
+    assert(chan < 124);
+    txWrite((chan * MHUv2_SND_CHAN_WINDOW_SIZE) + MHUv2_CH_INT_EN, 0);
+}
+
+/*
+ * Set channel status byte (with only minor error/state check(s))
+ * Doorbell only, chan 0
+ */
+bool MHUv2::sendMessage() {
+    // Check that the other end is ready to receive
+    if (!getAccessReady()) {
+        return false;
+    }
+    txWrite(MHUv2_CH_SET, 1);
+
+    return true;
+}
+
+void MHUv2::clearMessage() {
+    rxWrite(MHUv2_CH_CLR, 0xFFFFFFFF); // Doorbell uses only chan 0, but clear all 32bits to be safe
+}
+
+void MHUv2::txWrite(uint32_t offset, uint32_t value) {
+    write32(txBaseAddr, offset, value);
+}
+
+void MHUv2::rxWrite(uint32_t offset, uint32_t value) {
+    write32(rxBaseAddr, offset, value);
+}
+
+uint32_t MHUv2::txRead(uint32_t offset) {
+    return read32(txBaseAddr, offset);
+}
+
+uint32_t MHUv2::rxRead(uint32_t offset) {
+    return read32(rxBaseAddr, offset);
+}
+
+void MHUv2::printAIDR(bool tx, bool rx) {
+    struct aidr_t *a;
+    uint32_t aidr;
+
+    if (tx) {
+        aidr = getTxAIDR();
+        a    = reinterpret_cast<struct aidr_t *>(&aidr);
+        printf("TX MHUv2 reports: Major rev: %d\nMinor rev: %d\n", a->ARCH_MAJOR_REV, a->ARCH_MINOR_REV);
+    }
+    if (rx) {
+        aidr = getRxAIDR();
+        a    = reinterpret_cast<struct aidr_t *>(&aidr);
+        printf("RX MHUv2 reports: Major rev: %d\nMinor rev: %d\n", a->ARCH_MAJOR_REV, a->ARCH_MINOR_REV);
+    }
+}
+
+} // namespace Mailbox