pw_sys_io_emcraft_sf2: Add basic UART I/O support

Introduces a GN-based build for the Emcraft Smartfusion 2 SOM.

   * Adds 'emcraft_sf2_som' as a pw_system target.
   * Smartfusion MSS HAL added to 'third_party'.

Change-Id: Ibdb4affdd11e5ba57659b90f8182ef0bc24ab9e7
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/86940
Reviewed-by: Keir Mierle <keir@google.com>
Reviewed-by: Armando Montanez <amontanez@google.com>
Commit-Queue: Sean Keys <skeys@google.com>

22 files changed, 747 insertions, 6 deletions

diff --git a/PIGWEED_MODULES b/PIGWEED_MODULES
index 9912ec7fb..dfb7f2725 100644
--- a/PIGWEED_MODULES
+++ b/PIGWEED_MODULES
@@ -92,6 +92,7 @@ pw_sys_io
 pw_sys_io_arduino
 pw_sys_io_baremetal_lm3s6965evb
 pw_sys_io_baremetal_stm32f429
+pw_sys_io_emcraft_sf2
 pw_sys_io_mcuxpresso
 pw_sys_io_stdio
 pw_sys_io_stm32cube
diff --git a/pw_build/generated_pigweed_modules_lists.gni b/pw_build/generated_pigweed_modules_lists.gni
index e5765eec1..f3d3627ef 100644
--- a/pw_build/generated_pigweed_modules_lists.gni
+++ b/pw_build/generated_pigweed_modules_lists.gni
@@ -126,6 +126,8 @@ declare_args() {
       get_path_info("../pw_sys_io_baremetal_lm3s6965evb", "abspath")
   dir_pw_sys_io_baremetal_stm32f429 =
       get_path_info("../pw_sys_io_baremetal_stm32f429", "abspath")
+  dir_pw_sys_io_emcraft_sf2 =
+      get_path_info("../pw_sys_io_emcraft_sf2", "abspath")
   dir_pw_sys_io_mcuxpresso = get_path_info("../pw_sys_io_mcuxpresso", "abspath")
   dir_pw_sys_io_stdio = get_path_info("../pw_sys_io_stdio", "abspath")
   dir_pw_sys_io_stm32cube = get_path_info("../pw_sys_io_stm32cube", "abspath")
@@ -254,6 +256,7 @@ declare_args() {
     dir_pw_sys_io_arduino,
     dir_pw_sys_io_baremetal_lm3s6965evb,
     dir_pw_sys_io_baremetal_stm32f429,
+    dir_pw_sys_io_emcraft_sf2,
     dir_pw_sys_io_mcuxpresso,
     dir_pw_sys_io_stdio,
     dir_pw_sys_io_stm32cube,
@@ -439,6 +442,7 @@ declare_args() {
     "$dir_pw_sys_io:docs",
     "$dir_pw_sys_io_arduino:docs",
     "$dir_pw_sys_io_baremetal_stm32f429:docs",
+    "$dir_pw_sys_io_emcraft_sf2:docs",
     "$dir_pw_sys_io_mcuxpresso:docs",
     "$dir_pw_sys_io_stdio:docs",
     "$dir_pw_sys_io_stm32cube:docs",
diff --git a/pw_package/py/BUILD.gn b/pw_package/py/BUILD.gn
index bfc46a8d1..1af696e78 100644
--- a/pw_package/py/BUILD.gn
+++ b/pw_package/py/BUILD.gn
@@ -38,6 +38,7 @@ pw_python_package("py") {
     "pw_package/packages/nanopb.py",
     "pw_package/packages/pico_sdk.py",
     "pw_package/packages/protobuf.py",
+    "pw_package/packages/smartfusion_mss.py",
     "pw_package/packages/stm32cube.py",
     "pw_package/pigweed_packages.py",
   ]
diff --git a/pw_package/py/pw_package/packages/smartfusion_mss.py b/pw_package/py/pw_package/packages/smartfusion_mss.py
new file mode 100644
index 000000000..b9dbe49c7
--- /dev/null
+++ b/pw_package/py/pw_package/packages/smartfusion_mss.py
@@ -0,0 +1,40 @@
+# Copyright 2022 The Pigweed Authors
+#
+# 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
+#
+#     https://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.
+"""Install and check status of SmartFusion MSS."""
+
+import pathlib
+from typing import Sequence
+
+import pw_package.git_repo
+import pw_package.package_manager
+
+
+class SmartfusionMss(pw_package.git_repo.GitRepo):
+    """Install and check status of SmartFusion MSS."""
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args,
+                         name='smartfusion_mss',
+                         url='https://github.com/seank/smartfusion_mss',
+                         commit='9f47db73d3df786eab04d082645da5e735e63d28',
+                         **kwargs)
+
+    def info(self, path: pathlib.Path) -> Sequence[str]:
+        return (
+            f'{self.name} installed in: {path}',
+            "Enable by running 'gn args out' and adding this line:",
+            f'  dir_pw_third_party_smartfusion_mss = "{path}"',
+        )
+
+
+pw_package.package_manager.register(SmartfusionMss)
diff --git a/pw_package/py/pw_package/pigweed_packages.py b/pw_package/py/pw_package/pigweed_packages.py
index 59e0919c7..c60468c9b 100644
--- a/pw_package/py/pw_package/pigweed_packages.py
+++ b/pw_package/py/pw_package/pigweed_packages.py
@@ -27,6 +27,7 @@ from pw_package.packages import micro_ecc  # pylint: disable=unused-import
 from pw_package.packages import nanopb
 from pw_package.packages import pico_sdk  # pylint: disable=unused-import
 from pw_package.packages import protobuf  # pylint: disable=unused-import
+from pw_package.packages import smartfusion_mss  # pylint: disable=unused-import
 from pw_package.packages import stm32cube  # pylint: disable=unused-import
 
 
diff --git a/pw_sys_io_emcraft_sf2/BUILD.bazel b/pw_sys_io_emcraft_sf2/BUILD.bazel
new file mode 100644
index 000000000..fb10a78c4
--- /dev/null
+++ b/pw_sys_io_emcraft_sf2/BUILD.bazel
@@ -0,0 +1,39 @@
+# Copyright 2022 The Pigweed Authors
+#
+# 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
+#
+#     https://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.
+
+load(
+    "//pw_build:pigweed.bzl",
+    "pw_cc_library",
+)
+
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+pw_cc_library(
+    name = "pw_sys_io_emcraft_sf2",
+    srcs = [
+        "pw_sys_io_emcraft_sf2_private/config.h",
+        "sys_io_emcraft_sf2.cc",
+    ],
+    hdrs = ["public/pw_sys_io_emcraft_sf2/init.h"],
+    target_compatible_with = [
+        "@platforms//os:none",
+    ],
+    deps = [
+        "//pw_boot_cortex_m:armv7m",
+        "//pw_preprocessor",
+        "//pw_sys_io",
+    ],
+)
diff --git a/pw_sys_io_emcraft_sf2/BUILD.gn b/pw_sys_io_emcraft_sf2/BUILD.gn
new file mode 100644
index 000000000..236722f70
--- /dev/null
+++ b/pw_sys_io_emcraft_sf2/BUILD.gn
@@ -0,0 +1,60 @@
+# Copyright 2022 The Pigweed Authors
+#
+# 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
+#
+#     https://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.
+
+import("//build_overrides/pigweed.gni")
+
+import("$dir_pw_build/module_config.gni")
+import("$dir_pw_build/target_types.gni")
+import("$dir_pw_docgen/docs.gni")
+import("$dir_pw_third_party/smartfusion_mss/mss.gni")
+
+declare_args() {
+  # The build target that overrides the default configuration options for this
+  # module. This should point to a source set that provides defines through a
+  # public config (which may -include a file or add defines directly).
+  pw_sys_io_emcraft_sf2_CONFIG = pw_build_DEFAULT_MODULE_CONFIG
+}
+
+config("public_includes") {
+  include_dirs = [ "public" ]
+}
+
+pw_source_set("config") {
+  public_deps = [ pw_sys_io_emcraft_sf2_CONFIG ]
+  public = [ "pw_sys_io_emcraft_sf2_private/config.h" ]
+  visibility = [ ":*" ]
+}
+
+pw_source_set("pw_sys_io_emcraft_sf2") {
+  public_configs = [ ":public_includes" ]
+  public_deps = [
+    "$dir_pw_preprocessor",
+    "$dir_pw_third_party/smartfusion_mss",
+  ]
+  if (dir_pw_third_party_smartfusion_mss != "") {
+    public_deps += [ "$dir_pw_third_party/smartfusion_mss" ]
+  }
+  public = [ "public/pw_sys_io_emcraft_sf2/init.h" ]
+  sources = [ "sys_io_emcraft_sf2.cc" ]
+  deps = [
+    ":config",
+    "$dir_pw_status",
+    "$dir_pw_sys_io:default_putget_bytes",
+    "$dir_pw_sys_io:facade",
+  ]
+}
+
+pw_doc_group("docs") {
+  sources = [ "docs.rst" ]
+}
diff --git a/pw_sys_io_emcraft_sf2/docs.rst b/pw_sys_io_emcraft_sf2/docs.rst
new file mode 100644
index 000000000..66ef6c940
--- /dev/null
+++ b/pw_sys_io_emcraft_sf2/docs.rst
@@ -0,0 +1,44 @@
+.. _module-pw_sys_io_emcraft_sf2:
+
+---------------------
+pw_sys_io_emcraft_sf2
+---------------------
+
+``pw_sys_io_emcraft_sf2`` implements the ``pw_sys_io`` facade over
+UART.
+
+The Emcraft SF2 sys IO backend provides a UART driver layer that allows
+applications built against the ``pw_sys_io`` interface to run on a
+SmartFusion/2 chip and do simple input/output via UART. However, this should
+work with all Smartfusion/2 variations.
+
+This backend allows you to configure which UART to use. The point of it is to
+provide bare-minimum platform code needed to do UART reads/writes.
+
+Setup
+=====
+This module requires relatively minimal setup:
+
+  1. Write code against the ``pw_sys_io`` facade.
+  2. Specify the ``dir_pw_sys_io_backend`` GN global variable to point to this
+     backend.
+  3. pw_sys_io_Init() provided by this module needs to be called in early boot
+     to get pw_sys_io into a working state.
+  4. Build an executable with a main() function using a toolchain that
+     supports Cortex-M3.
+
+.. note::
+  This module provides early firmware init, so it will conflict with other
+  modules that do any early device init.
+
+Module usage
+============
+After building an executable that utilizes this backend, flash the
+produced .elf binary to the development board. Then, using a serial
+communication terminal like minicom/screen (Linux/Mac) or TeraTerm (Windows),
+connect to the device at a baud rate of 57600 (8N1).
+
+Dependencies
+============
+  * ``pw_sys_io`` facade
+  * ``pw_preprocessor`` module
diff --git a/pw_sys_io_emcraft_sf2/public/pw_sys_io_emcraft_sf2/init.h b/pw_sys_io_emcraft_sf2/public/pw_sys_io_emcraft_sf2/init.h
new file mode 100644
index 000000000..ccfd61e3c
--- /dev/null
+++ b/pw_sys_io_emcraft_sf2/public/pw_sys_io_emcraft_sf2/init.h
@@ -0,0 +1,23 @@
+// Copyright 2022 The Pigweed Authors
+//
+// 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
+//
+//     https://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.
+#pragma once
+
+#include "pw_preprocessor/util.h"
+
+PW_EXTERN_C_START
+
+// The actual implement of PreMainInit() in sys_io_BACKEND.
+void pw_sys_io_Init(void);
+
+PW_EXTERN_C_END
diff --git a/pw_sys_io_emcraft_sf2/pw_sys_io_emcraft_sf2_private/config.h b/pw_sys_io_emcraft_sf2/pw_sys_io_emcraft_sf2_private/config.h
new file mode 100644
index 000000000..fb3db3a17
--- /dev/null
+++ b/pw_sys_io_emcraft_sf2/pw_sys_io_emcraft_sf2_private/config.h
@@ -0,0 +1,22 @@
+// Copyright 2022 The Pigweed Authors
+//
+// 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
+//
+//     https://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.
+
+#pragma once
+
+// Defaults to USART1 on the SmartFusion2, but can be overridden.
+
+// The USART peripheral number to use. (1 for USART1, 2 for USART2, etc.)
+#ifndef PW_SYS_IO_EMCRAFT_SF2_USART_NUM
+#define PW_SYS_IO_EMCRAFT_SF2_USART_NUM 1
+#endif  // PW_SYS_IO_EMCRAFT_SF2_USART_NUM
diff --git a/pw_sys_io_emcraft_sf2/sys_io_emcraft_sf2.cc b/pw_sys_io_emcraft_sf2/sys_io_emcraft_sf2.cc
new file mode 100644
index 000000000..d94a621b5
--- /dev/null
+++ b/pw_sys_io_emcraft_sf2/sys_io_emcraft_sf2.cc
@@ -0,0 +1,104 @@
+// Copyright 2022 The Pigweed Authors
+//
+// 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
+//
+//     https://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 <cinttypes>
+
+#include "mss_gpio/mss_gpio.h"
+#include "mss_uart/mss_uart.h"
+#include "pw_preprocessor/concat.h"
+#include "pw_status/status.h"
+#include "pw_sys_io/sys_io.h"
+#include "pw_sys_io_emcraft_sf2_private/config.h"
+
+namespace {
+
+// LEDs GPIOs
+
+constexpr mss_gpio_id_t kDs3LedGPIO = MSS_GPIO_1;
+constexpr mss_gpio_id_t kDs4LEDGPIO = MSS_GPIO_2;
+constexpr uint32_t kDs3LedMask = MSS_GPIO_1_MASK;
+constexpr uint32_t kDs4LedMask = MSS_GPIO_2_MASK;
+
+constexpr uint32_t kReadDataReady = 0x1u;
+
+}  // namespace
+
+extern "C" void pw_sys_io_Init() {
+  // Configure MSS GPIOs.
+#if SF2_MSS_NO_BOOTLOADER
+  MSS_GPIO_init();
+#endif
+
+  MSS_GPIO_config(kDs3LedGPIO, MSS_GPIO_OUTPUT_MODE);
+  MSS_GPIO_config(kDs4LEDGPIO, MSS_GPIO_OUTPUT_MODE);
+  // Set LEDs to initial app state
+  MSS_GPIO_set_outputs(MSS_GPIO_get_outputs() | kDs4LedMask);
+
+  // Initialize the UART0 controller (57600, 8N1)
+  // Due to a HW eratta in SF2, we need to run at 57600 for
+  // in-system-programming mode. If we are not upgrading FPGA or flash then we
+  // can use a faster BAUD.
+  MSS_UART_init(
+      &g_mss_uart0,
+      MSS_UART_57600_BAUD,
+      MSS_UART_DATA_8_BITS | MSS_UART_NO_PARITY | MSS_UART_ONE_STOP_BIT);
+}
+
+// This whole implementation is very inefficient because it uses the synchronous
+// polling UART API and only reads / writes 1 byte at a time.
+namespace pw::sys_io {
+
+Status ReadByte(std::byte* dest) {
+  while (true) {
+    if (TryReadByte(dest).ok()) {
+      return OkStatus();
+    }
+  }
+}
+
+Status TryReadByte(std::byte* dest) {
+  if (!(g_mss_uart0.hw_reg->LSR & kReadDataReady)) {
+    return Status::Unavailable();
+  }
+
+  *dest = static_cast<std::byte>(g_mss_uart0.hw_reg->RBR);
+  return OkStatus();
+}
+
+Status WriteByte(std::byte b) {
+  // Wait for TX buffer to be empty. When the buffer is empty, we can write
+  // a value to be dumped out of UART.
+  const uint8_t pbuff = (uint8_t)b;
+
+  MSS_UART_polled_tx(&g_mss_uart0, &pbuff, 1);
+  return OkStatus();
+}
+
+// Writes a string using pw::sys_io, and add newline characters at the end.
+StatusWithSize WriteLine(const std::string_view& s) {
+  size_t chars_written = 0;
+  StatusWithSize result = WriteBytes(std::as_bytes(std::span(s)));
+  if (!result.ok()) {
+    return result;
+  }
+  chars_written += result.size();
+
+  // Write trailing newline.
+  result = WriteBytes(std::as_bytes(std::span("\r\n", 2)));
+  chars_written += result.size();
+
+  return StatusWithSize(OkStatus(), chars_written);
+}
+
+}  // namespace pw::sys_io
diff --git a/pw_system/BUILD.gn b/pw_system/BUILD.gn
index 089fbd1e2..fd5cb5ad8 100644
--- a/pw_system/BUILD.gn
+++ b/pw_system/BUILD.gn
@@ -16,6 +16,7 @@ import("//build_overrides/pigweed.gni")
 
 import("$dir_pigweed/third_party/freertos/freertos.gni")
 import("$dir_pigweed/third_party/nanopb/nanopb.gni")
+import("$dir_pigweed/third_party/smartfusion_mss/mss.gni")
 import("$dir_pigweed/third_party/stm32cube/stm32cube.gni")
 import("$dir_pw_build/error.gni")
 import("$dir_pw_build/facade.gni")
@@ -226,6 +227,14 @@ if (dir_pw_third_party_nanopb != "") {
         dir_pw_third_party_freertos != "") {
       deps += [ ":system_example($dir_pigweed/targets/stm32f429i_disc1_stm32cube:stm32f429i_disc1_stm32cube.size_optimized)" ]
     }
+    if (dir_pw_third_party_smartfusion_mss != "" &&
+        dir_pw_third_party_freertos != "") {
+      deps += [
+        ":system_example($dir_pigweed/targets/emcraft_sf2_som:emcraft_sf2_som.size_optimized)",
+        ":system_example($dir_pigweed/targets/emcraft_sf2_som:emcraft_sf2_som.speed_optimized)",
+        ":system_example($dir_pigweed/targets/emcraft_sf2_som:emcraft_sf2_som_debug.debug)",
+      ]
+    }
   }
 } else {
   pw_error("system_examples") {
diff --git a/targets/emcraft_sf2_som/BUILD.gn b/targets/emcraft_sf2_som/BUILD.gn
index 007fa4672..9d778698e 100644
--- a/targets/emcraft_sf2_som/BUILD.gn
+++ b/targets/emcraft_sf2_som/BUILD.gn
@@ -18,8 +18,10 @@ import("$dir_pw_build/target_types.gni")
 import("$dir_pw_docgen/docs.gni")
 import("$dir_pw_malloc/backend.gni")
 import("$dir_pw_system/system_target.gni")
+import("$dir_pw_third_party/smartfusion_mss/mss.gni")
 import("$dir_pw_tokenizer/backend.gni")
 import("$dir_pw_toolchain/generate_toolchain.gni")
+
 config("pw_malloc_active") {
   if (pw_malloc_BACKEND != "") {
     defines = [ "PW_MALLOC_ACTIVE=1" ]
@@ -35,9 +37,9 @@ if (current_toolchain != default_toolchain) {
       "$dir_pw_malloc",
       "$dir_pw_preprocessor",
       "$dir_pw_string",
+      "$dir_pw_sys_io_emcraft_sf2",
       "$dir_pw_system",
       "$dir_pw_third_party/freertos",
-      "$dir_pw_third_party/smartfusion_mss",
     ]
     sources = [
       "boot.cc",
@@ -51,7 +53,9 @@ if (current_toolchain != default_toolchain) {
 
   pw_source_set("sf2_mss_hal_config") {
     public_configs = [ ":config_includes" ]
-    public = [ "config/sf2_mss_hal_conf.h" ]
+    public =
+        [ "config/sf2_mss_hal_conf.h" ]  # SKEYS likely want to put the MDDR
+                                         # config by cortex etc stuff here
   }
 
   pw_source_set("sf2_freertos_config") {
@@ -61,17 +65,68 @@ if (current_toolchain != default_toolchain) {
   }
 }
 
+# Configured for use with a first stage boot loader to configure DDR and
+# perform memory remapping.
 pw_system_target("emcraft_sf2_som") {
   cpu = PW_SYSTEM_CPU.CORTEX_M3
   scheduler = PW_SYSTEM_SCHEDULER.FREERTOS
+  link_deps = [ "$dir_pigweed/targets/emcraft_sf2_som:pre_init" ]
+
+  build_args = {
+    pw_log_BACKEND = dir_pw_log_tokenized
+    pw_tokenizer_GLOBAL_HANDLER_WITH_PAYLOAD_BACKEND =
+        "$dir_pw_system:log_backend.impl"
+    pw_third_party_freertos_CONFIG =
+        "$dir_pigweed/targets/emcraft_sf2_som:sf2_freertos_config"
+    pw_third_party_freertos_PORT = "$dir_pw_third_party/freertos:arm_cm3"
+    pw_sys_io_BACKEND = dir_pw_sys_io_emcraft_sf2
+
+    # Non-debug build for use with the boot loader.
+    pw_boot_cortex_m_LINK_CONFIG_DEFINES = [
+      "PW_BOOT_FLASH_BEGIN=0x00000200",  # After vector table.
+
+      # TODO(skeys) Bootloader is capable of loading 16M of uncompressed code
+      # from SPI flash to external RAM. For now use the allocated eNVM flash
+      # (256K - Bootloader - InSystemProgrammer = 192K)
+      "PW_BOOT_FLASH_SIZE=0x30000",
 
+      # TODO(pwbug/219): Currently "pw_tokenizer/detokenize_test" requires at
+      # least 6K bytes in heap when using pw_malloc_freelist. The heap size
+      # required for tests should be investigated.
+      "PW_BOOT_HEAP_SIZE=4M",
+
+      # With external RAM remapped, we use the entire internal ram for the
+      # stack (64K).
+      "PW_BOOT_MIN_STACK_SIZE=1024K",
+
+      # Using external DDR RAM, we just need to make sure we go past our ROM
+      # sections.
+      "PW_BOOT_RAM_BEGIN=0xA1000000",
+
+      # We assume that the bootloader loaded all 16M of text.
+      "PW_BOOT_RAM_SIZE=48M",
+      "PW_BOOT_VECTOR_TABLE_BEGIN=0x00000000",
+      "PW_BOOT_VECTOR_TABLE_SIZE=512",
+    ]
+  }
+}
+
+# Debug target configured to work with MSS linker script and startup code.
+# TODO(skeys) Add linker script and config for debug builds using SoftConsole.
+pw_system_target("emcraft_sf2_som_debug") {
+  cpu = PW_SYSTEM_CPU.CORTEX_M3
+  scheduler = PW_SYSTEM_SCHEDULER.FREERTOS
   link_deps = [ "$dir_pigweed/targets/emcraft_sf2_som:pre_init" ]
+
   build_args = {
     pw_log_BACKEND = dir_pw_log_tokenized
-    pw_tokenizer_GLOBAL_HANDLER_WITH_PAYLOAD_BACKEND = "//pw_system:log"
+    pw_tokenizer_GLOBAL_HANDLER_WITH_PAYLOAD_BACKEND =
+        "$dir_pw_system:log_backend.impl"
     pw_third_party_freertos_CONFIG =
         "$dir_pigweed/targets/emcraft_sf2_som:sf2_freertos_config"
     pw_third_party_freertos_PORT = "$dir_pw_third_party/freertos:arm_cm3"
+    pw_sys_io_BACKEND = dir_pw_sys_io_emcraft_sf2
+
     pw_boot_cortex_m_LINK_CONFIG_DEFINES = [
       "PW_BOOT_FLASH_BEGIN=0x00000200",
       "PW_BOOT_FLASH_SIZE=200K",
diff --git a/targets/emcraft_sf2_som/boot.cc b/targets/emcraft_sf2_som/boot.cc
index 284860b2f..bb786c850 100644
--- a/targets/emcraft_sf2_som/boot.cc
+++ b/targets/emcraft_sf2_som/boot.cc
@@ -17,14 +17,19 @@
 #include <array>
 
 #include "FreeRTOS.h"
+#include "config/sf2_mss_hal_conf.h"
+#include "m2sxxx.h"
 #include "pw_boot_cortex_m/boot.h"
 #include "pw_malloc/malloc.h"
 #include "pw_preprocessor/compiler.h"
 #include "pw_string/util.h"
 #include "pw_sys_io_emcraft_sf2/init.h"
 #include "pw_system/init.h"
+#include "system_m2sxxx.h"
 #include "task.h"
 
+#include liberosoc_CONFIG_FILE
+
 namespace {
 
 std::array<StackType_t, configMINIMAL_STACK_SIZE> freertos_idle_stack;
@@ -68,7 +73,98 @@ extern "C" void vApplicationGetIdleTaskMemory(
   *pulIdleTaskStackSize = freertos_timer_stack.size();
 }
 
-extern "C" void pw_boot_PreStaticMemoryInit() {}
+extern "C" void pw_boot_PreStaticMemoryInit() {
+#if SF2_MSS_NO_BOOTLOADER
+  SystemInit();
+  // Initialize DDR
+  // inclusive-language: disable
+  MDDR->core.ddrc.DYN_SOFT_RESET_CR = 0x0000;
+  MDDR->core.ddrc.DYN_REFRESH_1_CR = 0x27de;
+  MDDR->core.ddrc.DYN_REFRESH_2_CR = 0x030f;
+  MDDR->core.ddrc.DYN_POWERDOWN_CR = 0x0002;
+  MDDR->core.ddrc.DYN_DEBUG_CR = 0x0000;
+  MDDR->core.ddrc.MODE_CR = 0x00C1;
+  MDDR->core.ddrc.ADDR_MAP_BANK_CR = 0x099f;
+  MDDR->core.ddrc.ECC_DATA_MASK_CR = 0x0000;
+  MDDR->core.ddrc.ADDR_MAP_COL_1_CR = 0x3333;
+  MDDR->core.ddrc.ADDR_MAP_COL_2_CR = 0xffff;
+  MDDR->core.ddrc.ADDR_MAP_ROW_1_CR = 0x7777;
+  MDDR->core.ddrc.ADDR_MAP_ROW_2_CR = 0x0fff;
+  MDDR->core.ddrc.INIT_1_CR = 0x0001;
+  MDDR->core.ddrc.CKE_RSTN_CYCLES_CR[0] = 0x4242;
+  MDDR->core.ddrc.CKE_RSTN_CYCLES_CR[1] = 0x0008;
+  MDDR->core.ddrc.INIT_MR_CR = 0x0033;
+  MDDR->core.ddrc.INIT_EMR_CR = 0x0020;
+  MDDR->core.ddrc.INIT_EMR2_CR = 0x0000;
+  MDDR->core.ddrc.INIT_EMR3_CR = 0x0000;
+  MDDR->core.ddrc.DRAM_BANK_TIMING_PARAM_CR = 0x00c0;
+  MDDR->core.ddrc.DRAM_RD_WR_LATENCY_CR = 0x0023;
+  MDDR->core.ddrc.DRAM_RD_WR_PRE_CR = 0x0235;
+  MDDR->core.ddrc.DRAM_MR_TIMING_PARAM_CR = 0x0064;
+  MDDR->core.ddrc.DRAM_RAS_TIMING_CR = 0x0108;
+  MDDR->core.ddrc.DRAM_RD_WR_TRNARND_TIME_CR = 0x0178;
+  MDDR->core.ddrc.DRAM_T_PD_CR = 0x0033;
+  MDDR->core.ddrc.DRAM_BANK_ACT_TIMING_CR = 0x1947;
+  MDDR->core.ddrc.ODT_PARAM_1_CR = 0x0010;
+  MDDR->core.ddrc.ODT_PARAM_2_CR = 0x0000;
+  MDDR->core.ddrc.ADDR_MAP_COL_3_CR = 0x3300;
+  MDDR->core.ddrc.MODE_REG_RD_WR_CR = 0x0000;
+  MDDR->core.ddrc.MODE_REG_DATA_CR = 0x0000;
+  MDDR->core.ddrc.PWR_SAVE_1_CR = 0x0514;
+  MDDR->core.ddrc.PWR_SAVE_2_CR = 0x0000;
+  MDDR->core.ddrc.ZQ_LONG_TIME_CR = 0x0200;
+  MDDR->core.ddrc.ZQ_SHORT_TIME_CR = 0x0040;
+  MDDR->core.ddrc.ZQ_SHORT_INT_REFRESH_MARGIN_CR[0] = 0x0012;
+  MDDR->core.ddrc.ZQ_SHORT_INT_REFRESH_MARGIN_CR[1] = 0x0002;
+  MDDR->core.ddrc.PERF_PARAM_1_CR = 0x4000;
+  MDDR->core.ddrc.HPR_QUEUE_PARAM_CR[0] = 0x80f8;
+  MDDR->core.ddrc.HPR_QUEUE_PARAM_CR[1] = 0x0007;
+  MDDR->core.ddrc.LPR_QUEUE_PARAM_CR[0] = 0x80f8;
+  MDDR->core.ddrc.LPR_QUEUE_PARAM_CR[1] = 0x0007;
+  MDDR->core.ddrc.WR_QUEUE_PARAM_CR = 0x0200;
+  MDDR->core.ddrc.PERF_PARAM_2_CR = 0x0001;
+  MDDR->core.ddrc.PERF_PARAM_3_CR = 0x0000;
+  MDDR->core.ddrc.DFI_RDDATA_EN_CR = 0x0003;
+  MDDR->core.ddrc.DFI_MIN_CTRLUPD_TIMING_CR = 0x0003;
+  MDDR->core.ddrc.DFI_MAX_CTRLUPD_TIMING_CR = 0x0040;
+  MDDR->core.ddrc.DFI_WR_LVL_CONTROL_CR[0] = 0x0000;
+  MDDR->core.ddrc.DFI_WR_LVL_CONTROL_CR[1] = 0x0000;
+  MDDR->core.ddrc.DFI_RD_LVL_CONTROL_CR[0] = 0x0000;
+  MDDR->core.ddrc.DFI_RD_LVL_CONTROL_CR[1] = 0x0000;
+  MDDR->core.ddrc.DFI_CTRLUPD_TIME_INTERVAL_CR = 0x0309;
+  MDDR->core.ddrc.AXI_FABRIC_PRI_ID_CR = 0x0000;
+  MDDR->core.ddrc.ECC_INT_CLR_REG = 0x0000;
+
+  MDDR->core.phy.LOOPBACK_TEST_CR = 0x0000;
+  MDDR->core.phy.CTRL_SLAVE_RATIO_CR = 0x0080;
+  MDDR->core.phy.DATA_SLICE_IN_USE_CR = 0x0003;
+  MDDR->core.phy.DQ_OFFSET_CR[0] = 0x00000000;
+  MDDR->core.phy.DQ_OFFSET_CR[2] = 0x0000;
+  MDDR->core.phy.DLL_LOCK_DIFF_CR = 0x000B;
+  MDDR->core.phy.FIFO_WE_SLAVE_RATIO_CR[0] = 0x0040;
+  MDDR->core.phy.FIFO_WE_SLAVE_RATIO_CR[1] = 0x0401;
+  MDDR->core.phy.FIFO_WE_SLAVE_RATIO_CR[2] = 0x4010;
+  MDDR->core.phy.FIFO_WE_SLAVE_RATIO_CR[3] = 0x0000;
+  MDDR->core.phy.LOCAL_ODT_CR = 0x0001;
+  MDDR->core.phy.RD_DQS_SLAVE_RATIO_CR[0] = 0x0040;
+  MDDR->core.phy.RD_DQS_SLAVE_RATIO_CR[1] = 0x0401;
+  MDDR->core.phy.RD_DQS_SLAVE_RATIO_CR[2] = 0x4010;
+  MDDR->core.phy.WR_DATA_SLAVE_RATIO_CR[0] = 0x0040;
+  MDDR->core.phy.WR_DATA_SLAVE_RATIO_CR[1] = 0x0401;
+  MDDR->core.phy.WR_DATA_SLAVE_RATIO_CR[2] = 0x4010;
+  MDDR->core.phy.WR_RD_RL_CR = 0x0021;
+  MDDR->core.phy.RDC_WE_TO_RE_DELAY_CR = 0x0003;
+  MDDR->core.phy.USE_FIXED_RE_CR = 0x0001;
+  MDDR->core.phy.USE_RANK0_DELAYS_CR = 0x0001;
+  MDDR->core.phy.CONFIG_CR = 0x0009;
+  MDDR->core.phy.DYN_RESET_CR = 0x01;
+  MDDR->core.ddrc.DYN_SOFT_RESET_CR = 0x01;
+  // inclusive-language: enable
+  // Wait for config
+  while ((MDDR->core.ddrc.DDRC_SR) == 0x0000) {
+  }
+#endif
+}
 
 extern "C" void pw_boot_PreStaticConstructorInit() {
   // TODO(skeys) add "#if no_bootLoader" and the functions needed for init.
diff --git a/targets/emcraft_sf2_som/config/sf2_mss_hal_conf.h b/targets/emcraft_sf2_som/config/sf2_mss_hal_conf.h
index 2f16d2e40..0e82d6856 100644
--- a/targets/emcraft_sf2_som/config/sf2_mss_hal_conf.h
+++ b/targets/emcraft_sf2_som/config/sf2_mss_hal_conf.h
@@ -14,8 +14,12 @@
 
 #pragma once
 
+#if (MSS_SYS_MDDR_CONFIG_BY_CORTEX == 1)
+#error "Please turn off DDR initialization! See the comment in this file above."
+#endif
+
 #define HAL_GPIO_MODULE_ENABLED
-#include "mss_gpio.h"
+#include "mss_gpio/mss_gpio.h"
 
 #define HAL_UART_MODULE_ENABLED
-#include "mss_uart.h"
+#include "mss_uart/mss_uart.h"
diff --git a/third_party/smartfusion_mss/BUILD.bazel b/third_party/smartfusion_mss/BUILD.bazel
new file mode 100644
index 000000000..bf4dfa0d7
--- /dev/null
+++ b/third_party/smartfusion_mss/BUILD.bazel
@@ -0,0 +1,40 @@
+# Copyright 2022 The Pigweed Authors
+#
+# 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
+#
+#     https://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.
+
+load(
+    "//pw_build:pigweed.bzl",
+    "pw_cc_library",
+)
+
+# Ready-made configurations
+liberosoc_configs = [
+    ("default", "configs/config_default.h"),
+    ("debug", "configs/config_debug.h"),
+]
+
+# Config targets.
+[
+    pw_cc_library(
+        name = "%s_config" % config_name,
+        hdrs = [
+            config_header,
+            "configs/config_pigweed_common.h",
+        ],
+        copts = ["-Dmss_CONFIG_FILE=\"%s\"" % config_header],
+        includes = ["."],
+    )
+    for config_name, config_header in liberosoc_configs
+]
+
+# TODO(skeys): Add build recipe for the library.
diff --git a/third_party/smartfusion_mss/BUILD.gn b/third_party/smartfusion_mss/BUILD.gn
new file mode 100644
index 000000000..2e3c10888
--- /dev/null
+++ b/third_party/smartfusion_mss/BUILD.gn
@@ -0,0 +1,112 @@
+# Copyright 2022 The Pigweed Authors
+#
+# 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
+#
+#     https://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.
+
+import("//build_overrides/pigweed.gni")
+import("$dir_pw_build/linker_script.gni")
+import("$dir_pw_build/target_types.gni")
+import("$dir_pw_third_party/smartfusion_mss/mss.gni")
+
+declare_args() {
+  pw_target_smartfusion2_LINK_CONFIG_DEFINES = []
+}
+
+if (dir_pw_third_party_smartfusion_mss != "") {
+  # The list currently includes all source files for build.
+  smartfusion_mss_sources = [
+    "exported_firmware/CMSIS/startup_gcc/startup_m2sxxx.S",
+    "exported_firmware/CMSIS/system_m2sxxx.c",
+    "exported_firmware/drivers/mss_can/mss_can.c",
+    "exported_firmware/drivers/mss_ethernet_mac/m88e1340_phy.c",
+    "exported_firmware/drivers/mss_ethernet_mac/mss_ethernet_mac.c",
+    "exported_firmware/drivers/mss_gpio/mss_gpio.c",
+    "exported_firmware/drivers/mss_hpdma/mss_hpdma.c",
+    "exported_firmware/drivers/mss_i2c/mss_i2c.c",
+    "exported_firmware/drivers/mss_nvm/mss_nvm.c",
+    "exported_firmware/drivers/mss_rtc/mss_rtc.c",
+    "exported_firmware/drivers/mss_spi/mss_spi.c",
+    "exported_firmware/drivers/mss_sys_services/mss_comblk.c",
+    "exported_firmware/drivers/mss_sys_services/mss_sys_services.c",
+    "exported_firmware/drivers/mss_uart/mss_uart.c",
+    "exported_firmware/drivers/mss_usb/mss_usb_common_cif.c",
+    "exported_firmware/drivers/mss_usb/mss_usb_device.c",
+    "exported_firmware/drivers/mss_usb/mss_usb_device_cdc.c",
+    "exported_firmware/drivers/mss_usb/mss_usb_device_cif.c",
+    "exported_firmware/drivers/mss_usb/mss_usb_device_hid.c",
+    "exported_firmware/drivers/mss_usb/mss_usb_device_msd.c",
+    "exported_firmware/drivers/mss_usb/mss_usb_device_printer.c",
+    "exported_firmware/drivers/mss_usb/mss_usb_device_rndis.c",
+    "exported_firmware/drivers/mss_usb/mss_usb_device_vendor.c",
+    "exported_firmware/drivers/mss_usb/mss_usb_host.c",
+    "exported_firmware/drivers/mss_usb/mss_usb_host_cif.c",
+    "exported_firmware/drivers/mss_usb/mss_usb_host_msc.c",
+    "exported_firmware/drivers_config/sys_config/sys_config.c",
+  ]
+
+  liberosoc_configs = [
+    {
+      name = "default"
+      config_header = "configs/config_default.h"
+    },
+    {
+      name = "debug"
+      config_header = "configs/config_debug.h"
+    },
+  ]
+
+  foreach(ele, liberosoc_configs) {
+    config_name = ele.name + "_config"
+    config(config_name) {
+      # Custom config file is specified by macro liberosoc_CONFIG_FILE
+      # for liberosoc
+      defines = [ "liberosoc_CONFIG_FILE=\"${ele.config_header}\"" ]
+    }
+
+    srcset_name = ele.name + "_config_srcset"
+    pw_source_set(srcset_name) {
+      public = [
+        "configs/config_pigweed_common.h",
+        ele.config_header,
+      ]
+      public_configs = [
+        ":${config_name}",
+        ":smartfusion_mss_common_config",
+      ]
+    }
+  }
+
+  config("smartfusion_mss_common_config") {
+    include_dirs = [
+      "$dir_pw_third_party_smartfusion_mss/exported_firmware/CMSIS/V4.5/Include",
+      "$dir_pw_third_party_smartfusion_mss/exported_firmware/drivers",
+      "$dir_pw_third_party_smartfusion_mss/exported_firmware/CMSIS",
+      "$dir_pw_third_party/smartfusion_mss",
+    ]
+    cflags = [
+      "-Wno-error=cast-qual",
+      "-Wno-error=redundant-decls",
+      "-w",
+    ]
+  }
+
+  pw_source_set("smartfusion_mss") {
+    sources = []
+    foreach(source, smartfusion_mss_sources) {
+      sources += [ "$dir_pw_third_party_smartfusion_mss/" + source ]
+    }
+    public_deps = [ ":${pw_third_party_smartfusion_mss_CONFIG}_config_srcset" ]
+  }
+} else {
+  group("smartfusion_mss") {
+  }
+}
diff --git a/third_party/smartfusion_mss/README.md b/third_party/smartfusion_mss/README.md
new file mode 100644
index 000000000..7532545e2
--- /dev/null
+++ b/third_party/smartfusion_mss/README.md
@@ -0,0 +1,6 @@
+# LiberoSoC Library
+
+The folder provides build scripts and configuration recipes for building
+the SmartFusion2 Microcontroller Subsystem library. The source code needs to be downloaded by the user, or
+via the support in pw_package "pw package install sf2mss". For gn build,
+set `dir_pw_third_party_smartfusion_mss` to point to the path of the source code.
diff --git a/third_party/smartfusion_mss/configs/config_debug.h b/third_party/smartfusion_mss/configs/config_debug.h
new file mode 100644
index 000000000..7eb69608e
--- /dev/null
+++ b/third_party/smartfusion_mss/configs/config_debug.h
@@ -0,0 +1,19 @@
+// Copyright 2022 The Pigweed Authors
+//
+// 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
+//
+//     https://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.
+
+#pragma once
+
+#include "configs/config_pigweed_common.h"
+
+#define SF2_MSS_NO_BOOTLOADER 1
diff --git a/third_party/smartfusion_mss/configs/config_default.h b/third_party/smartfusion_mss/configs/config_default.h
new file mode 100644
index 000000000..30aee591f
--- /dev/null
+++ b/third_party/smartfusion_mss/configs/config_default.h
@@ -0,0 +1,17 @@
+// Copyright 2022 The Pigweed Authors
+//
+// 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
+//
+//     https://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.
+
+#pragma once
+
+#include "configs/config_pigweed_common.h"
diff --git a/third_party/smartfusion_mss/configs/config_pigweed_common.h b/third_party/smartfusion_mss/configs/config_pigweed_common.h
new file mode 100644
index 000000000..3f4f6ea45
--- /dev/null
+++ b/third_party/smartfusion_mss/configs/config_pigweed_common.h
@@ -0,0 +1,20 @@
+// Copyright 2022 The Pigweed Authors
+//
+// 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
+//
+//     https://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.
+
+// Some common configs for using mbedtls in Pigweed. These include disabling of
+// file system, socket and linux/windows specific features.
+// See include/mbedtls/config.h for a detail explanation of these
+// configurations.
+
+#pragma once
diff --git a/third_party/smartfusion_mss/mss.gni b/third_party/smartfusion_mss/mss.gni
new file mode 100644
index 000000000..dd971781a
--- /dev/null
+++ b/third_party/smartfusion_mss/mss.gni
@@ -0,0 +1,24 @@
+# Copyright 2022 The Pigweed Authors
+#
+# 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
+#
+#     https://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.
+
+declare_args() {
+  # If compiling backends with mbedtls, this variable is set to the path to the
+  # mbedtls source code. When set, a pw_source_set for the mbedtls library is
+  # created at "$dir_pw_third_party/mbedtls".
+  dir_pw_third_party_smartfusion_mss = ""
+
+  # configuration for mbedtls. Can be one of `mbedtls_configs` in the BUILD.gn
+  # file
+  pw_third_party_smartfusion_mss_CONFIG = "default"
+}