TFLu: Add stm32f4 and build target

Add new TARGET=stm32f4 that is working with Renode.
Add new <build> target that will just build the test binaries.
Add new CI script for this as well.
The purpose of this is CMSIS-NN regression.

tensorflow/lite/micro/stm32f4/debug_log.cc

@@ -0,0 +1,25 @@
+/* Copyright 2020 The TensorFlow Authors. All Rights Reserved.
+
+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
+
+    http://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 "tensorflow/lite/micro/debug_log.h"
+
+extern "C" void DebugLog(const char* s) {
+  asm("mov r0, #0x04\n"  // SYS_WRITE0
+      "mov r1, %[str]\n"
+      "bkpt #0xAB\n"
+      :
+      : [ str ] "r"(s)
+      : "r0", "r1");
+}

tensorflow/lite/micro/tools/ci_build/test_all.sh

@@ -49,4 +49,7 @@ tensorflow/lite/micro/tools/ci_build/test_sparkfun.sh
 echo "Running x86 tests at `date`"
 tensorflow/lite/micro/tools/ci_build/test_x86.sh
 
+echo "Running stm32f4 tests at `date`"
+tensorflow/lite/micro/tools/ci_build/test_stm32f4.sh
+
 echo "Finished all micro tests at `date`"

tensorflow/lite/micro/tools/ci_build/test_stm32f4.sh

@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+# Copyright 2020 The TensorFlow Authors. All Rights Reserved.
+#
+# 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
+#
+#     http://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.
+# ==============================================================================
+#
+# Tests the microcontroller code for stm32f4
+
+set -e
+
+TARGET=stm32f4
+TAGS=cmsis-nn
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+ROOT_DIR=${SCRIPT_DIR}/../../../../..
+cd ${ROOT_DIR}
+pwd
+
+source tensorflow/lite/micro/tools/ci_build/helper_functions.sh
+
+readable_run make -f tensorflow/lite/micro/tools/make/Makefile clean
+
+# TODO(b/143715361): downloading first to allow for parallel builds.
+readable_run make -f tensorflow/lite/micro/tools/make/Makefile TAGS=${TAGS} TARGET=${TARGET} third_party_downloads
+
+# Build test binaries first
+readable_run make -j8 -f tensorflow/lite/micro/tools/make/Makefile TAGS=${TAGS} TARGET=${TARGET} build
+
+# Parallell builds doesn't work very well with this
+readable_run make -f tensorflow/lite/micro/tools/make/Makefile TAGS=${TAGS} TARGET=${TARGET} test
+

tensorflow/lite/micro/tools/make/Makefile

@@ -81,6 +81,8 @@ CC_PREFIX :=
 # runtime that can be linked in to other programs.
 MICROLITE_LIB_NAME := libtensorflow-microlite.a
 
+MICRO_LITE_EXAMPLE_TESTS := $(wildcard tensorflow/lite/micro/examples/*/Makefile.inc)
+
 MICROLITE_TEST_SRCS := \
 $(wildcard tensorflow/lite/micro/*test.cc) \
 $(wildcard tensorflow/lite/micro/kernels/*test.cc) \
@@ -240,7 +242,7 @@ CC := $(CC_PREFIX)${TARGET_TOOLCHAIN_PREFIX}${CC_TOOL}
 AR := $(CC_PREFIX)${TARGET_TOOLCHAIN_PREFIX}${AR_TOOL}
 
 # Load the examples.
-include $(wildcard tensorflow/lite/micro/examples/*/Makefile.inc)
+include $(MICRO_LITE_EXAMPLE_TESTS)
 
 # Create rules for downloading third-party dependencies.
 THIRD_PARTY_TARGETS :=
@@ -308,6 +310,9 @@ $(eval $(call microlite_test,kernel_$(notdir $(basename $(TEST_TARGET))),$(TEST_
 
 test: $(MICROLITE_TEST_TARGETS)
 
+# Just build the test targets
+build: $(MICROLITE_BUILD_TARGETS)
+
 generate_projects: $(ALL_PROJECT_TARGETS)
 
 generate_non_kernel_projects: $(filter-out generate_kernel%,$(ALL_PROJECT_TARGETS))

tensorflow/lite/micro/tools/make/helper_functions.inc

@@ -371,6 +371,7 @@ test_$(1): $$($(1)_BINARY)
 	$$(TEST_SCRIPT) $$($(1)_BINARY) '~~~ALL TESTS PASSED~~~'
 ifneq (,$(findstring _test,$(1)))
   MICROLITE_TEST_TARGETS += test_$(1)
+  MICROLITE_BUILD_TARGETS += $$($(1)_BINARY)
 endif
 $(eval $(call generate_microlite_projects,$(1),$(call specialize,$(2)),$(3)))
 endef

tensorflow/lite/micro/tools/make/targets/stm32f4/stm32f4.lds

@@ -0,0 +1,102 @@
+/* Copyright 2020 Google Inc. All Rights Reserved.
+
+Copyright 2020 The TensorFlow Authors. All Rights Reserved.
+
+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
+    http://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.
+==============================================================================*/
+
+/* Copied and modified from: tensorflow/lite/micro/tools/make/targets/bluepill/bluepill.lds
+
+*/
+
+/*
+ * 0x00000000 - 0x07ffffff - aliased to flash or sys memory depending on BOOT jumpers.
+ * 0x08000000 - 0x0801ffff - Flash.
+ * 0x1ffff000 - 0x1ffff7ff - Boot firmware in system memory.
+ * 0x1ffff800 - 0x1fffffff - Option bytes.
+ * 0x20000000 - 0x20004fff - SRAM.
+ * 0x40000000 - 0x40023400 - Peripherals
+ */
+
+/* Define main entry point */
+ENTRY(_main)
+
+/* 20K of RAM and 128K of FLASH */
+MEMORY {
+RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 20K
+FLASH (rx) : ORIGIN = 0x8000000, LENGTH = 256K
+}
+
+/* Compute where the stack ends rather than hard coding it */
+_ld_stack_end_addr = ORIGIN(RAM) + LENGTH(RAM);
+_ld_min_stack_size = 0x200;
+
+SECTIONS {
+
+/* interrupt vector goes to top of flash */
+
+.interrupt_vector : {
+  . = ALIGN(4);
+  KEEP(*(.interrupt_vector))
+  . = ALIGN(4);
+} >FLASH
+
+/* read only .text and .rodata go to flash */
+
+.text : {
+  . = ALIGN(4);
+  KEEP(*(.text.interrupt_handler))
+  *(.text*)
+} >FLASH
+
+.rodata : {
+  . = ALIGN(4);
+  *(.rodata*)
+  . = ALIGN(4);
+} >FLASH
+
+/* read mwrite data needs to be stored in flash but copied to ram */
+.data : {
+  . = ALIGN(4);
+  _ld_data_load_dest_start = .; /* export where to load from */
+  *(.data*)
+  . = ALIGN(4);
+  _ld_data_load_dest_stop = .; /* export where to load from */
+} >RAM AT> FLASH
+_ld_data_load_source = LOADADDR(.data);
+
+/* unitialized data section needs zero initialization */
+.bss :
+{
+  . = ALIGN(4);
+  _ld_bss_data_start = .;
+  *(.bss*)
+  . = ALIGN(4);
+  _ld_bss_data_stop = .;
+} >RAM
+
+._user_heap_stack :
+{
+  . = ALIGN(8);
+  . += _ld_min_stack_size;
+  PROVIDE(end = .);
+  . = ALIGN(8);
+} >RAM
+
+/DISCARD/ :
+{
+  libc.a (*)
+  libm.a (*)
+  libgcc.a (*)
+}
+
+}  /* SECTIONS */

tensorflow/lite/micro/tools/make/targets/stm32f4_makefile.inc

@@ -0,0 +1,86 @@
+# Settings for stm32f4 based platforms
+ifeq ($(TARGET), stm32f4)
+  export PATH := $(MAKEFILE_DIR)/downloads/gcc_embedded/bin/:$(PATH)
+  TARGET_ARCH := cortex-m4
+  TARGET_TOOLCHAIN_PREFIX := arm-none-eabi-
+
+  $(eval $(call add_third_party_download,$(GCC_EMBEDDED_URL),$(GCC_EMBEDDED_MD5),gcc_embedded,))
+  $(eval $(call add_third_party_download,$(CMSIS_URL),$(CMSIS_MD5),cmsis,))
+  $(eval $(call add_third_party_download,$(STM32_BARE_LIB_URL),$(STM32_BARE_LIB_MD5),stm32_bare_lib,))
+
+  PLATFORM_FLAGS = \
+    -DGEMMLOWP_ALLOW_SLOW_SCALAR_FALLBACK \
+    -DTF_LITE_STATIC_MEMORY \
+    -DTF_LITE_MCU_DEBUG_LOG \
+    -fno-rtti \
+    -fmessage-length=0 \
+    -fno-exceptions \
+    -fno-unwind-tables \
+    -fno-builtin \
+    -ffunction-sections \
+    -fdata-sections \
+    -funsigned-char \
+    -MMD \
+    -mcpu=cortex-m4 \
+    -mthumb \
+    -std=gnu++11 \
+    -Wvla \
+    -Wall \
+    -Wextra \
+    -Wno-unused-parameter \
+    -Wno-missing-field-initializers \
+    -Wno-write-strings \
+    -Wno-sign-compare \
+    -fno-delete-null-pointer-checks \
+    -fomit-frame-pointer \
+    -fpermissive \
+    -g \
+    -Os
+  CXXFLAGS += $(PLATFORM_FLAGS)
+  CCFLAGS += $(PLATFORM_FLAGS)
+  LDFLAGS += \
+    --specs=nosys.specs \
+    -T $(MAKEFILE_DIR)/targets/stm32f4/stm32f4.lds \
+    -Wl,-Map=$(MAKEFILE_DIR)/gen/$(TARGET).map,--cref \
+    -Wl,--gc-sections
+  BUILD_TYPE := micro
+  MICROLITE_LIBS := \
+    -lm
+  INCLUDES += \
+    -isystem$(MAKEFILE_DIR)/downloads/cmsis/CMSIS/Core/Include/ \
+    -I$(MAKEFILE_DIR)/downloads/stm32_bare_lib/include
+  MICROLITE_CC_SRCS += \
+    $(wildcard $(MAKEFILE_DIR)/downloads/stm32_bare_lib/source/*.c) \
+    $(wildcard $(MAKEFILE_DIR)/downloads/stm32_bare_lib/source/*.cc)
+  EXCLUDED_SRCS := \
+    $(MAKEFILE_DIR)/downloads/stm32_bare_lib/source/debug_log.c
+  MICROLITE_CC_SRCS := $(filter-out $(EXCLUDED_SRCS), $(MICROLITE_CC_SRCS))
+  # Stm32f4 is reusing the bluepill renode scripts for now
+  TEST_SCRIPT := tensorflow/lite/micro/testing/test_bluepill_binary.sh
+  # TODO, non working tests.. the micro_speech example and conv_test.cc/depthwise_conv_test.cc partly works
+  EXCLUDED_TESTS := \
+    tensorflow/lite/micro/micro_interpreter_test.cc \
+    tensorflow/lite/micro/micro_allocator_test.cc \
+    tensorflow/lite/micro/memory_helpers_test.cc \
+    tensorflow/lite/micro/kernels/depthwise_conv_test.cc \
+    tensorflow/lite/micro/kernels/conv_test.cc \
+    tensorflow/lite/micro/simple_tensor_allocator_test.cc
+  MICROLITE_TEST_SRCS := $(filter-out $(EXCLUDED_TESTS), $(MICROLITE_TEST_SRCS))
+  EXCLUDED_EXAMPLE_TESTS := \
+    tensorflow/lite/micro/examples/magic_wand/Makefile.inc \
+    tensorflow/lite/micro/examples/person_detection/Makefile.inc \
+    tensorflow/lite/micro/examples/person_detection_experimental/Makefile.inc \
+    tensorflow/lite/micro/examples/mobilenet_v2/Makefile.inc \
+    tensorflow/lite/micro/examples/micro_speech/Makefile.inc \
+    tensorflow/lite/micro/examples/ds_cnn_l/Makefile.inc
+  MICRO_LITE_EXAMPLE_TESTS := $(filter-out $(EXCLUDED_EXAMPLE_TESTS), $(MICRO_LITE_EXAMPLE_TESTS))
+
+# These are microcontroller-specific rules for converting the ELF output
+# of the linker into a binary image that can be loaded directly.
+OBJCOPY := $(TARGET_TOOLCHAIN_PREFIX)objcopy
+
+$(BINDIR)/%.bin: $(BINDIR)/%
+	@mkdir -p $(dir $@)
+	$(OBJCOPY) $< $@ -O binary
+
+endif