Improved Logging - Core Software

Logging macros:
Added ethosu_logging.h as a lib, containing logging macros controlled by
a parameter ETHOSU_LOG_SEVERITY set in core_software CMakeLists.txt

Updated inference_process:
Updated inference_process to include ethosu_logging and use the logging
macros rather than printf()

Updated message_process:
Updated message_process to include ethosu_logging and use the
logging macros rather than printf()

Updated ethosu_monitor:
Updated ethosu_monitor to include ethosu_logging and use the
logging macros rather than printf()

Updated layer_by_layer_profiler:
Updated layer_by_layer_profiler to include ethosu_logging and use the
logging macros rather than printf()

Updated mhu_v2:
Updated mhu_v2 to include ethosu_logging and use the
logging macros rather than printf()

Change-Id: I5d6fd80b7645b3e0af5b494eea6dbb7755f02122

14 files changed, 227 insertions, 100 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index cc0d39e..62db31e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -42,6 +42,16 @@ set_property(CACHE CORE_SOFTWARE_ACCELERATOR PROPERTY STRINGS CPU CMSIS-NN NPU)
 set(CORE_SOFTWARE_RTOS "None" CACHE STRING "Select RTOS to include. (None, MbedOS, FreeRTOS, Zephyr)")
 string(TOLOWER ${CORE_SOFTWARE_RTOS} CORE_SOFTWARE_RTOS_LOWER)
 
+set(LOG_NAMES err warning info debug)
+set(ETHOSU_LOG_SEVERITY "warning" CACHE STRING "Driver log severity level ${LOG_NAMES} (Defaults to warning)")
+set_property(CACHE ETHOSU_LOG_SEVERITY PROPERTY STRINGS ${LOG_NAMES})
+
+# Check that ETHOSU_LOG_SEVERITY has one of the supported levels
+list(FIND LOG_NAMES ${ETHOSU_LOG_SEVERITY} LOG_SEVERITY)
+if (${LOG_SEVERITY} EQUAL -1)
+    message(FATAL_ERROR "Unsupported log level ${ETHOSU_LOG_SEVERITY}")
+endif()
+
 #
 # Build
 #
@@ -78,3 +88,10 @@ add_subdirectory(drivers)
 
 # Merge libraries into static library
 target_link_libraries(ethosu_core INTERFACE tflu ethosu_applications ethosu_drivers)
+
+message(STATUS "*******************************************************")
+message(STATUS "PROJECT_NAME                           : ${PROJECT_NAME}")
+message(STATUS "CORE_SOFTWARE_RTOS                     : ${CORE_SOFTWARE_RTOS}")
+message(STATUS "CORE_SOFTWARE_ACCELERATOR              : ${CORE_SOFTWARE_ACCELERATOR}")
+message(STATUS "ETHOSU_LOG_SEVERITY                    : ${ETHOSU_LOG_SEVERITY}")
+message(STATUS "*******************************************************")
\ No newline at end of file
diff --git a/applications/inference_process/CMakeLists.txt b/applications/inference_process/CMakeLists.txt
index 1378181..19777fd 100644
--- a/applications/inference_process/CMakeLists.txt
+++ b/applications/inference_process/CMakeLists.txt
@@ -30,5 +30,8 @@ endif()
 if (TARGET arm_profiler)
     target_link_libraries(inference_process PRIVATE arm_profiler)
 endif()
+if (TARGET ethosu_log)
+    target_link_libraries(inference_process PRIVATE ethosu_log)
+endif()
 
-target_sources(inference_process PRIVATE src/inference_process.cpp)
+target_sources(inference_process PRIVATE src/inference_process.cpp)
\ No newline at end of file
diff --git a/applications/inference_process/src/inference_process.cpp b/applications/inference_process/src/inference_process.cpp
index 13cabb2..7058f9c 100644
--- a/applications/inference_process/src/inference_process.cpp
+++ b/applications/inference_process/src/inference_process.cpp
@@ -27,6 +27,7 @@
 #ifdef ETHOSU
 #include "layer_by_layer_profiler.hpp"
 #endif
+#include "ethosu_log.h"
 
 #include "inference_process.hpp"
 
@@ -39,30 +40,28 @@ using namespace std;
 namespace {
 
 void tflu_debug_log(const char *s) {
-    fprintf(stderr, "%s", s);
+    LOG_DEBUG("%s", s);
 }
 
 void print_output_data(TfLiteTensor *output, size_t bytesToPrint) {
     const int numBytesToPrint = min(output->bytes, bytesToPrint);
-
-    int dims_size = output->dims->size;
-    printf("{\n");
-    printf("\"dims\": [%d,", dims_size);
+    int dims_size             = output->dims->size;
+    LOG("{\n");
+    LOG("\"dims\": [%d,", dims_size);
     for (int i = 0; i < output->dims->size - 1; ++i) {
-        printf("%d,", output->dims->data[i]);
+        LOG("%d,", output->dims->data[i]);
     }
-    printf("%d],\n", output->dims->data[dims_size - 1]);
-
-    printf("\"data_address\": \"%08" PRIx32 "\",\n", (uint32_t)output->data.data);
-    printf("\"data\":\"");
+    LOG("%d],\n", output->dims->data[dims_size - 1]);
+    LOG("\"data_address\": \"%08" PRIx32 "\",\n", (uint32_t)output->data.data);
+    LOG("\"data\":\"");
     for (int i = 0; i < numBytesToPrint - 1; ++i) {
         if (i % 16 == 0 && i != 0) {
-            printf("\n");
+            LOG("\n");
         }
-        printf("0x%02x,", output->data.uint8[i]);
+        LOG("0x%02x,", output->data.uint8[i]);
     }
-    printf("0x%02x\"\n", output->data.uint8[numBytesToPrint - 1]);
-    printf("}");
+    LOG("0x%02x\"\n", output->data.uint8[numBytesToPrint - 1]);
+    LOG("}");
 }
 
 bool copyOutput(const TfLiteTensor &src, InferenceProcess::DataPtr &dst) {
@@ -71,7 +70,7 @@ bool copyOutput(const TfLiteTensor &src, InferenceProcess::DataPtr &dst) {
     }
 
     if (src.bytes > dst.size) {
-        printf("Tensor size %d does not match output size %d.\n", src.bytes, dst.size);
+        LOG_ERR("Tensor size mismatch (bytes): actual=%d, expected%d.\n", src.bytes, dst.size);
         return true;
     }
 
@@ -181,7 +180,7 @@ bool InferenceProcess::push(const InferenceJob &job) {
 }
 
 bool InferenceProcess::runJob(InferenceJob &job) {
-    printf("Running inference job: %s\n", job.name.c_str());
+    LOG_INFO("Running inference job: %s\n", job.name.c_str());
 
     // Register debug log callback for profiling
     RegisterDebugLogCallback(tflu_debug_log);
@@ -192,9 +191,9 @@ bool InferenceProcess::runJob(InferenceJob &job) {
     // Get model handle and verify that the version is correct
     const tflite::Model *model = ::tflite::GetModel(job.networkModel.data);
     if (model->version() != TFLITE_SCHEMA_VERSION) {
-        printf("Model provided is schema version %" PRIu32 " not equal to supported version %d.\n",
-               model->version(),
-               TFLITE_SCHEMA_VERSION);
+        LOG_ERR("Model schema version unsupported: version=%" PRIu32 ", supported=%d.\n",
+                model->version(),
+                TFLITE_SCHEMA_VERSION);
         return true;
     }
 
@@ -211,7 +210,7 @@ bool InferenceProcess::runJob(InferenceJob &job) {
     // Allocate tensors
     TfLiteStatus allocate_status = interpreter.AllocateTensors();
     if (allocate_status != kTfLiteOk) {
-        printf("AllocateTensors failed for inference job: %s\n", job.name.c_str());
+        LOG_ERR("Failed to allocate tensors for inference: job=%s\n", job.name.c_str());
         return true;
     }
 
@@ -225,9 +224,9 @@ bool InferenceProcess::runJob(InferenceJob &job) {
         }
     }
     if (job.input.size() != inputTensors.size()) {
-        printf("Number of input buffers does not match number of non empty network tensors. input=%zu, network=%zu\n",
-               job.input.size(),
-               inputTensors.size());
+        LOG_ERR("Number of input buffers does not match number of non empty network tensors: input=%zu, network=%zu\n",
+                job.input.size(),
+                inputTensors.size());
         return true;
     }
 
@@ -237,11 +236,11 @@ bool InferenceProcess::runJob(InferenceJob &job) {
         const TfLiteTensor *tensor = inputTensors[i];
 
         if (input.size != tensor->bytes) {
-            printf("Input size does not match network size. job=%s, index=%zu, input=%zu, network=%u\n",
-                   job.name.c_str(),
-                   i,
-                   input.size,
-                   tensor->bytes);
+            LOG_ERR("Job input size does not match network input size: job=%s, index=%zu, input=%zu, network=%u\n",
+                    job.name.c_str(),
+                    i,
+                    input.size,
+                    tensor->bytes);
             return true;
         }
 
@@ -251,13 +250,13 @@ bool InferenceProcess::runJob(InferenceJob &job) {
     // Run the inference
     TfLiteStatus invoke_status = interpreter.Invoke();
     if (invoke_status != kTfLiteOk) {
-        printf("Invoke failed for inference job: %s\n", job.name.c_str());
+        LOG_ERR("Invoke failed for inference: job=%s\n", job.name.c_str());
         return true;
     }
 
-    printf("%s : %zu\r\n", "arena_used_bytes", interpreter.arena_used_bytes());
+    LOG("arena_used_bytes : %zu\n", interpreter.arena_used_bytes());
 
-    printf("Inference runtime: %u cycles\r\n", (unsigned int)profiler.GetTotalTicks());
+    LOG("Inference runtime: %u cycles\n", (unsigned int)profiler.GetTotalTicks());
 
     if (job.pmuCycleCounterEnable != 0) {
         job.pmuCycleCounterCount = profiler.GetTotalTicks();
@@ -266,7 +265,7 @@ bool InferenceProcess::runJob(InferenceJob &job) {
     // Copy output data
     if (job.output.size() > 0) {
         if (interpreter.outputs_size() != job.output.size()) {
-            printf("Number of outputs mismatch. job=%zu, network=%u\n", job.output.size(), interpreter.outputs_size());
+            LOG_ERR("Output size mismatch: job=%zu, network=%u\n", job.output.size(), interpreter.outputs_size());
             return true;
         }
 
@@ -280,28 +279,26 @@ bool InferenceProcess::runJob(InferenceJob &job) {
     if (job.numBytesToPrint > 0) {
         // Print all of the output data, or the first NUM_BYTES_TO_PRINT bytes,
         // whichever comes first as well as the output shape.
-        printf("num_of_outputs: %d\n", interpreter.outputs_size());
-        printf("output_begin\n");
-        printf("[\n");
-
+        LOG("num_of_outputs: %d\n", interpreter.outputs_size());
+        LOG("output_begin\n");
+        LOG("[\n");
         for (unsigned int i = 0; i < interpreter.outputs_size(); i++) {
             TfLiteTensor *output = interpreter.output(i);
             print_output_data(output, job.numBytesToPrint);
             if (i != interpreter.outputs_size() - 1) {
-                printf(",\n");
+                LOG(",\n");
             }
         }
-
-        printf("]\n");
-        printf("output_end\n");
+        LOG("]\n");
+        LOG("output_end\n");
     }
 
     if (job.expectedOutput.size() > 0) {
         if (job.expectedOutput.size() != interpreter.outputs_size()) {
-            printf("Expected number of output tensors does not match network. job=%s, expected=%zu, network=%zu\n",
-                   job.name.c_str(),
-                   job.expectedOutput.size(),
-                   interpreter.outputs_size());
+            LOG_ERR("Expected number of output tensors mismatch: job=%s, expected=%zu, network=%zu\n",
+                    job.name.c_str(),
+                    job.expectedOutput.size(),
+                    interpreter.outputs_size());
             return true;
         }
 
@@ -310,33 +307,33 @@ bool InferenceProcess::runJob(InferenceJob &job) {
             const TfLiteTensor *output = interpreter.output(i);
 
             if (expected.size != output->bytes) {
-                printf("Expected tensor size does not match output size. job=%s, index=%u, expected=%zu, network=%zu\n",
-                       job.name.c_str(),
-                       i,
-                       expected.size,
-                       output->bytes);
+                LOG_ERR("Expected output tensor size mismatch: job=%s, index=%u, expected=%zu, network=%zu\n",
+                        job.name.c_str(),
+                        i,
+                        expected.size,
+                        output->bytes);
                 return true;
             }
 
             for (unsigned int j = 0; j < output->bytes; ++j) {
                 if (output->data.uint8[j] != static_cast<uint8_t *>(expected.data)[j]) {
-                    printf("Expected data does not match output data. job=%s, index=%u, offset=%u, "
-                           "expected=%02x, network=%02x\n",
-                           job.name.c_str(),
-                           i,
-                           j,
-                           static_cast<uint8_t *>(expected.data)[j],
-                           output->data.uint8[j]);
+                    LOG_ERR("Expected output tensor data mismatch: job=%s, index=%u, offset=%u, "
+                            "expected=%02x, network=%02x\n",
+                            job.name.c_str(),
+                            i,
+                            j,
+                            static_cast<uint8_t *>(expected.data)[j],
+                            output->data.uint8[j]);
                     return true;
                 }
             }
         }
     }
 
-    printf("Finished running job: %s\n", job.name.c_str());
+    LOG_INFO("Finished running job: %s\n", job.name.c_str());
 
     return false;
-}
+} // namespace InferenceProcess
 
 bool InferenceProcess::run(bool exitOnEmpty) {
     bool anyJobFailed = false;
@@ -348,7 +345,7 @@ bool InferenceProcess::run(bool exitOnEmpty) {
 
         if (empty) {
             if (exitOnEmpty) {
-                printf("Exit from InferenceProcess::run() on empty job queue!\n");
+                LOG_INFO("Exit from InferenceProcess::run() due to empty job queue\n");
                 break;
             }
 
diff --git a/applications/message_process/CMakeLists.txt b/applications/message_process/CMakeLists.txt
index 1e31d68..2122f14 100644
--- a/applications/message_process/CMakeLists.txt
+++ b/applications/message_process/CMakeLists.txt
@@ -19,7 +19,7 @@
 add_library(message_process STATIC src/message_process.cpp)
 target_include_directories(message_process PUBLIC include ${LINUX_DRIVER_STACK_PATH}/kernel)
 
-target_link_libraries(message_process PRIVATE cmsis_device inference_process ethosu_mailbox)
+target_link_libraries(message_process PRIVATE cmsis_device inference_process ethosu_mailbox ethosu_log)
 if (CORE_SOFTWARE_ACCELERATOR STREQUAL "NPU")
     target_link_libraries(message_process PRIVATE ethosu_core_driver)
-endif()
+endif()
\ No newline at end of file
diff --git a/applications/message_process/src/message_process.cpp b/applications/message_process/src/message_process.cpp
index cdd5c35..1669d3f 100644
--- a/applications/message_process/src/message_process.cpp
+++ b/applications/message_process/src/message_process.cpp
@@ -24,6 +24,8 @@
 
 #include "cmsis_compiler.h"
 
+#include "ethosu_log.h"
+
 #include <cstddef>
 #include <cstdio>
 #include <cstring>
@@ -198,7 +200,7 @@ bool MessageProcess::handleMessage() {
         return false;
     }
 
-    printf("Msg: header magic=%" PRIX32 ", type=%" PRIu32 ", length=%" PRIu32 "\n", msg.magic, msg.type, msg.length);
+    LOG_INFO("Msg: header magic=%" PRIX32 ", type=%" PRIu32 ", length=%" PRIu32 "\n", msg.magic, msg.type, msg.length);
 
     if (msg.magic != ETHOSU_CORE_MSG_MAGIC) {
         sndErrorRspAndResetQueue(ETHOSU_CORE_MSG_ERR_INVALID_MAGIC, "Invalid magic");
@@ -207,21 +209,21 @@ bool MessageProcess::handleMessage() {
 
     switch (msg.type) {
     case ETHOSU_CORE_MSG_PING:
-        printf("Msg: Ping\n");
+        LOG_INFO("Msg: Ping\n");
         sendPong();
         break;
     case ETHOSU_CORE_MSG_ERR: {
         struct ethosu_core_msg_err error = {0};
         if (!queueIn.read(error)) {
-            printf("ERROR: Msg: Failed to receive error message\n");
+            LOG_ERR("Msg: Failed to receive error message\n");
         } else {
-            printf("Msg: Received an error response, type=%" PRIu32 ", msg=\"%s\"\n", error.type, error.msg);
+            LOG_INFO("Msg: Received an error response, type=%" PRIu32 ", msg=\"%s\"\n", error.type, error.msg);
         }
         queueIn.reset();
         return false;
     }
     case ETHOSU_CORE_MSG_VERSION_REQ:
-        printf("Msg: Version request\n");
+        LOG_INFO("Msg: Version request\n");
         sendVersionRsp();
         break;
     case ETHOSU_CORE_MSG_CAPABILITIES_REQ: {
@@ -231,7 +233,7 @@ bool MessageProcess::handleMessage() {
             return false;
         }
 
-        printf("Msg: Capability request.user_arg=0x%" PRIx64 "", req.user_arg);
+        LOG_INFO("Msg: Capability request.user_arg=0x%" PRIx64 "\n", req.user_arg);
 
         sendCapabilityRsp(req.user_arg);
         break;
@@ -244,30 +246,30 @@ bool MessageProcess::handleMessage() {
             return false;
         }
 
-        printf("Msg: InferenceReq. user_arg=0x%" PRIx64 ", network={0x%" PRIx32 ", %" PRIu32 "}",
-               req.user_arg,
-               req.network.ptr,
-               req.network.size);
+        LOG_INFO("Msg: InferenceReq. user_arg=0x%" PRIx64 ", network={0x%" PRIx32 ", %" PRIu32 "}",
+                 req.user_arg,
+                 req.network.ptr,
+                 req.network.size);
 
-        printf(", ifm_count=%" PRIu32 ", ifm=[", req.ifm_count);
+        LOG_DEBUG_N(", ifm_count=%" PRIu32 ", ifm=[", req.ifm_count);
         for (uint32_t i = 0; i < req.ifm_count; ++i) {
             if (i > 0) {
-                printf(", ");
+                LOG_DEBUG_N(", ");
             }
 
-            printf("{0x%" PRIx32 ", %" PRIu32 "}", req.ifm[i].ptr, req.ifm[i].size);
+            LOG_DEBUG_N("{0x%" PRIx32 ", %" PRIu32 "}", req.ifm[i].ptr, req.ifm[i].size);
         }
-        printf("]");
+        LOG_DEBUG_N("]");
 
-        printf(", ofm_count=%" PRIu32 ", ofm=[", req.ofm_count);
+        LOG_DEBUG_N(", ofm_count=%" PRIu32 ", ofm=[", req.ofm_count);
         for (uint32_t i = 0; i < req.ofm_count; ++i) {
             if (i > 0) {
-                printf(", ");
+                LOG_DEBUG_N(", ");
             }
 
-            printf("{0x%" PRIx32 ", %" PRIu32 "}", req.ofm[i].ptr, req.ofm[i].size);
+            LOG_DEBUG_N("{0x%" PRIx32 ", %" PRIu32 "}", req.ofm[i].ptr, req.ofm[i].size);
         }
-        printf("]\n");
+        LOG_DEBUG_N("]\n");
 
         DataPtr networkModel(reinterpret_cast<void *>(req.network.ptr), req.network.size);
 
@@ -320,7 +322,7 @@ bool MessageProcess::handleMessage() {
 
 void MessageProcess::sendPong() {
     if (!queueOut.write(ETHOSU_CORE_MSG_PONG)) {
-        printf("ERROR: Msg: Failed to write pong response. No mailbox message sent\n");
+        LOG_ERR("Msg: Failed to write pong response. No mailbox message sent\n");
     } else {
         mailbox.sendMessage();
     }
@@ -335,7 +337,7 @@ void MessageProcess::sendVersionRsp() {
     };
 
     if (!queueOut.write(ETHOSU_CORE_MSG_VERSION_RSP, ver)) {
-        printf("ERROR: Failed to write version response. No mailbox message sent\n");
+        LOG_ERR("Msg: Failed to write version response. No mailbox message sent\n");
     } else {
         mailbox.sendMessage();
     }
@@ -389,7 +391,7 @@ void MessageProcess::sendCapabilityRsp(uint64_t userArg) {
 #endif
 
     if (!queueOut.write(ETHOSU_CORE_MSG_CAPABILITIES_RSP, capabilities)) {
-        printf("ERROR: Failed to write capability response. No mailbox message sent\n");
+        LOG_ERR("Failed to write capability response. No mailbox message sent\n");
     } else {
         mailbox.sendMessage();
     }
@@ -405,9 +407,9 @@ void MessageProcess::sndErrorRspAndResetQueue(ethosu_core_msg_err_type type, con
             error.msg[i] = message[i];
         }
     }
-    printf("ERROR: Msg: \"%s\"\n", message);
+    LOG_ERR("Msg: \"%s\"\n", message);
     if (!queueOut.write(ETHOSU_CORE_MSG_ERR, &error)) {
-        printf("ERROR: Msg: Failed to write error response. No mailbox message sent\n");
+        LOG_ERR("Msg: Failed to write error response. No mailbox message sent\n");
         return;
     }
     queueIn.reset();
@@ -445,13 +447,13 @@ void MessageProcess::sendInferenceRsp(uint64_t userArg,
     }
     rsp.pmu_cycle_counter_count = pmuCycleCounterCount;
 
-    printf("Sending inference response. userArg=0x%" PRIx64 ", ofm_count=%" PRIu32 ", status=%" PRIu32 "\n",
-           rsp.user_arg,
-           rsp.ofm_count,
-           rsp.status);
+    LOG_INFO("Sending inference response. userArg=0x%" PRIx64 ", ofm_count=%" PRIu32 ", status=%" PRIu32 "\n",
+             rsp.user_arg,
+             rsp.ofm_count,
+             rsp.status);
 
     if (!queueOut.write(ETHOSU_CORE_MSG_INFERENCE_RSP, rsp)) {
-        printf("ERROR: Msg: Failed to write inference response. No mailbox message sent\n");
+        LOG_ERR("Msg: Failed to write inference response. No mailbox message sent\n");
     } else {
         mailbox.sendMessage();
     }
diff --git a/drivers/mhu_v2/CMakeLists.txt b/drivers/mhu_v2/CMakeLists.txt
index 82a591a..2505901 100644
--- a/drivers/mhu_v2/CMakeLists.txt
+++ b/drivers/mhu_v2/CMakeLists.txt
@@ -20,4 +20,4 @@ add_library(ethosu_mhu_v2 STATIC)
 target_include_directories(ethosu_mhu_v2 PUBLIC include)
 
 target_sources(ethosu_mhu_v2 PRIVATE src/mhu_v2.cpp)
-target_link_libraries(ethosu_mhu_v2 PRIVATE ethosu_mailbox)
+target_link_libraries(ethosu_mhu_v2 PRIVATE ethosu_mailbox ethosu_log)
diff --git a/drivers/mhu_v2/src/mhu_v2.cpp b/drivers/mhu_v2/src/mhu_v2.cpp
index eb44a5d..3bcd256 100644
--- a/drivers/mhu_v2/src/mhu_v2.cpp
+++ b/drivers/mhu_v2/src/mhu_v2.cpp
@@ -16,6 +16,8 @@
  * limitations under the License.
  */
 
+#include "ethosu_log.h"
+
 #include <mhu_v2.hpp>
 
 #include <cassert>
@@ -195,12 +197,12 @@ void MHUv2::printAIDR(bool tx, bool rx) {
     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);
+        LOG_INFO("TX MHUv2 reports: Major rev: %d, Minor 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);
+        LOG_INFO("RX MHUv2 reports: Major rev: %d, Minor rev: %d\n", a->ARCH_MAJOR_REV, a->ARCH_MINOR_REV);
     }
 }
 
diff --git a/lib/CMakeLists.txt b/lib/CMakeLists.txt
index 5536949..7e47499 100644
--- a/lib/CMakeLists.txt
+++ b/lib/CMakeLists.txt
@@ -24,3 +24,6 @@ add_subdirectory(arm_profiler)
 
 # Build ethosu_monitor
 add_subdirectory(ethosu_monitor)
+
+# Build ethosu_logging
+add_subdirectory(ethosu_log)
\ No newline at end of file
diff --git a/lib/ethosu_log/CMakeLists.txt b/lib/ethosu_log/CMakeLists.txt
new file mode 100644
index 0000000..fbbed78
--- /dev/null
+++ b/lib/ethosu_log/CMakeLists.txt
@@ -0,0 +1,21 @@
+#
+# Copyright (c) 2021 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_log INTERFACE)
+target_include_directories(ethosu_log INTERFACE include)
+target_compile_definitions(ethosu_log INTERFACE ETHOSU_LOG_SEVERITY=${LOG_SEVERITY})
\ No newline at end of file
diff --git a/lib/ethosu_log/include/ethosu_log.h b/lib/ethosu_log/include/ethosu_log.h
new file mode 100644
index 0000000..4564b98
--- /dev/null
+++ b/lib/ethosu_log/include/ethosu_log.h
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2021 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 ETHOSU_LOG_H
+#define ETHOSU_LOG_H
+
+/******************************************************************************
+ * Includes
+ ******************************************************************************/
+
+#include <stdio.h>
+#include <string.h>
+
+/******************************************************************************
+ * Defines
+ ******************************************************************************/
+
+// Log severity levels
+#define ETHOSU_LOG_ERR   0
+#define ETHOSU_LOG_WARN  1
+#define ETHOSU_LOG_INFO  2
+#define ETHOSU_LOG_DEBUG 3
+
+// Define default log severity
+#ifndef ETHOSU_LOG_SEVERITY
+#define ETHOSU_LOG_SEVERITY ETHOSU_LOG_WARN
+#endif
+
+// Log formatting
+
+#define LOG(f, ...) fprintf(stdout, f, ##__VA_ARGS__)
+
+#if ETHOSU_LOG_SEVERITY >= ETHOSU_LOG_ERR
+#define LOG_ERR_N(f, ...) fprintf(stderr, f, ##__VA_ARGS__)
+#define LOG_ERR(f, ...)   LOG_ERR_N("E: " f " (%s:%d)", ##__VA_ARGS__, strrchr("/" __FILE__, '/') + 1, __LINE__)
+#else
+#define LOG_ERR(f, ...)
+#define LOG_ERR_N(f, ...)
+#endif
+
+#if ETHOSU_LOG_SEVERITY >= ETHOSU_LOG_WARN
+#define LOG_WARN_N(f, ...) fprintf(stdout, f, ##__VA_ARGS__)
+#define LOG_WARN(f, ...)   LOG_WARN_N("W: " f, ##__VA_ARGS__)
+#else
+#define LOG_WARN(f, ...)
+#define LOG_WARN_N(f, ...)
+#endif
+
+#if ETHOSU_LOG_SEVERITY >= ETHOSU_LOG_INFO
+#define LOG_INFO_N(f, ...) fprintf(stdout, f, ##__VA_ARGS__)
+#define LOG_INFO(f, ...)   LOG_INFO_N("I: " f, ##__VA_ARGS__)
+#else
+#define LOG_INFO(f, ...)
+#define LOG_INFO_N(f, ...)
+#endif
+
+#if ETHOSU_LOG_SEVERITY >= ETHOSU_LOG_DEBUG
+#define LOG_DEBUG_N(f, ...) fprintf(stdout, f, ##__VA_ARGS__)
+#define LOG_DEBUG(f, ...)   LOG_DEBUG_N("D: %s(): " f, __FUNCTION__, ##__VA_ARGS__)
+#else
+#define LOG_DEBUG(f, ...)
+#define LOG_DEBUG_N(f, ...)
+#endif
+
+#endif
\ No newline at end of file
diff --git a/lib/ethosu_monitor/CMakeLists.txt b/lib/ethosu_monitor/CMakeLists.txt
index 50f6526..7983c48 100644
--- a/lib/ethosu_monitor/CMakeLists.txt
+++ b/lib/ethosu_monitor/CMakeLists.txt
@@ -21,6 +21,6 @@ if (NOT TARGET ethosu_core_driver)
 endif()
 add_library(ethosu_monitor INTERFACE)
 
-target_link_libraries(ethosu_monitor INTERFACE ethosu_core_driver event_recorder)
+target_link_libraries(ethosu_monitor INTERFACE ethosu_core_driver event_recorder ethosu_log)
 target_include_directories(ethosu_monitor INTERFACE include)
 target_sources(ethosu_monitor INTERFACE src/ethosu_monitor.cpp)
diff --git a/lib/ethosu_monitor/src/ethosu_monitor.cpp b/lib/ethosu_monitor/src/ethosu_monitor.cpp
index d5cfce9..651fc28 100644
--- a/lib/ethosu_monitor/src/ethosu_monitor.cpp
+++ b/lib/ethosu_monitor/src/ethosu_monitor.cpp
@@ -17,6 +17,7 @@
  */
 
 #include "ethosu_monitor.hpp"
+#include "ethosu_log.h"
 #include <stdio.h>
 
 EthosUMonitor::EthosUMonitor(std::vector<int32_t> __eventRecordIds, Backend __backend) :
@@ -33,7 +34,7 @@ void EthosUMonitor::monitorSample(ethosu_driver *drv) {
             break;
         case PRINTF:
         default:
-            printf("ethosu_pmu_cntr%d : %u\n", i, eventCount[i]);
+            LOG("ethosu_pmu_cntr%d : %u\n", i, eventCount[i]);
         }
     }
 }
diff --git a/lib/layer_by_layer_profiler/CMakeLists.txt b/lib/layer_by_layer_profiler/CMakeLists.txt
index 9774685..7a16da2 100644
--- a/lib/layer_by_layer_profiler/CMakeLists.txt
+++ b/lib/layer_by_layer_profiler/CMakeLists.txt
@@ -21,6 +21,6 @@ if (NOT TARGET ethosu_core_driver)
 endif()
 
 add_library(layer_by_layer_profiler INTERFACE)
-target_link_libraries(layer_by_layer_profiler INTERFACE ethosu_core_driver tflu event_recorder)
+target_link_libraries(layer_by_layer_profiler INTERFACE ethosu_core_driver tflu event_recorder ethosu_log)
 target_include_directories(layer_by_layer_profiler INTERFACE include)
 target_sources(layer_by_layer_profiler INTERFACE src/layer_by_layer_profiler.cpp)
diff --git a/lib/layer_by_layer_profiler/src/layer_by_layer_profiler.cpp b/lib/layer_by_layer_profiler/src/layer_by_layer_profiler.cpp
index f7922cb..0211414 100644
--- a/lib/layer_by_layer_profiler/src/layer_by_layer_profiler.cpp
+++ b/lib/layer_by_layer_profiler/src/layer_by_layer_profiler.cpp
@@ -23,6 +23,7 @@
 
 #include <string.h>
 
+#include "ethosu_log.h"
 #include "layer_by_layer_profiler.hpp"
 #include <ethosu_driver.h>
 #include <inttypes.h>
@@ -88,9 +89,9 @@ void LayerByLayerProfiler::EndEvent(uint32_t event_handle) {
     }
 
     if (backend_ == PRINTF) {
-        printf("%s : cycle_cnt : %" PRIu64 " cycles\n",
-               tags_[event_handle],
-               end_ticks_[event_handle] - start_ticks_[event_handle]);
+        LOG("%s : cycle_cnt : %" PRIu64 " cycles\n",
+            tags_[event_handle],
+            end_ticks_[event_handle] - start_ticks_[event_handle]);
     } else {
         EventRecord2(event_id_, (int32_t)event_handle, end_ticks_[event_handle] - start_ticks_[event_handle]);
     }
@@ -112,7 +113,7 @@ void LayerByLayerProfiler::Log() const {
     if (backend_ == PRINTF) {
         for (size_t i = 0; i < num_events_; ++i) {
             uint64_t ticks = end_ticks_[i] - start_ticks_[i];
-            printf("%s took %" PRIu64 " cycles\n", tags_[i], ticks);
+            LOG("%s took %" PRIu64 " cycles", tags_[i], ticks);
         }
     }
 #endif