zephyr: forward cros_crc8 to zephyrs crc8 impl

Shim in support for crc8 used in CBI, I2C, and other
applications within platform/ec

BRANCH=none
BUG=b:168032589
TEST=add unit test for platform/ec and zephyr based
     CRC8 approaches and verify they both pass.

Signed-off-by: Jett Rink <jettrink@chromium.org>
Change-Id: I9b6112cb83dab81a44a1ac020d4efb1b7bb1df5f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2532692
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>

test/crc.c

@@ -8,6 +8,7 @@
 #include "common.h"
 #include "console.h"
 #include "crc.h"
+#include "crc8.h"
 #include "test_util.h"
 #include "util.h"
 
@@ -63,6 +64,18 @@ static int test_kat0(void)
 	return EC_SUCCESS;
 }
 
+static int test_cros_crc8(void)
+{
+	uint8_t buffer[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 8 };
+
+	int crc = cros_crc8(buffer, 10);
+
+	/* Verifies polynomial values of 0x07 representing x^8 + x^2 + x + 1 */
+	TEST_EQ(crc, 170, "%d");
+
+	return EC_SUCCESS;
+}
+
 void run_test(int argc, char **argv)
 {
 	test_reset();
@@ -70,6 +83,7 @@ void run_test(int argc, char **argv)
 	RUN_TEST(test_static_version);
 	RUN_TEST(test_8);
 	RUN_TEST(test_kat0);
+	RUN_TEST(test_cros_crc8);
 
 	test_print_result();
 }

test/test_config.h

@@ -220,6 +220,7 @@ enum sensor_id {
 #endif
 
 #ifdef TEST_CRC
+#define CONFIG_CRC8
 #define CONFIG_SW_CRC
 #endif
 

zephyr/shim/src/CMakeLists.txt

@@ -5,6 +5,7 @@
 zephyr_sources(console.c)
 zephyr_sources(gpio.c)
 zephyr_sources(util.c)
+zephyr_sources(crc.c)
 
 zephyr_sources_ifdef(CONFIG_PLATFORM_EC_HOOKS hooks.c)
 zephyr_sources_ifdef(CONFIG_PLATFORM_EC_TIMER hwtimer.c)

zephyr/shim/src/crc.c

@@ -0,0 +1,21 @@
+/* Copyright 2020 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <sys/crc.h>
+
+#include "crc8.h"
+
+/* Polynomial representation for x^8 + x^2 + x + 1 is 0x07 */
+#define SMBUS_POLYNOMIAL 0x07
+
+inline uint8_t cros_crc8(const uint8_t *data, int len)
+{
+	return crc8(data, len, SMBUS_POLYNOMIAL, 0, false);
+}
+
+uint8_t cros_crc8_arg(const uint8_t *data, int len, uint8_t previous_crc)
+{
+	return crc8(data, len, SMBUS_POLYNOMIAL, previous_crc, false);
+}

zephyr/test/crc/CMakeLists.txt

@@ -0,0 +1,17 @@
+# Copyright 2020 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.13.1)
+set(BOARD native_posix)
+project(tasks)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+
+# We need to include the EC include directory and this local test directory
+# for the task defines
+zephyr_include_directories("${PLATFORM_EC}/include")
+
+# Include the test source and the file under test
+target_sources(app PRIVATE main.c)
+target_sources(app PRIVATE "${CMAKE_CURRENT_SOURCE_DIR}/../../shim/src/crc.c")

zephyr/test/crc/main.c

@@ -0,0 +1,27 @@
+/* Copyright 2020 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <kernel.h>
+#include <ztest.h>
+
+#include "crc8.h"
+
+/* Note this test makes the pure platform/ec test that uses the same value */
+static void test_crc8_known_data(void)
+{
+	uint8_t buffer[10] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 8 };
+
+	int crc = cros_crc8(buffer, 10);
+
+	/* Verifies polynomial values of 0x07 representing x^8 + x^2 + x + 1 */
+	zassert_equal(crc, 170, "CRC8 hash did not match");
+}
+
+void test_main(void)
+{
+	ztest_test_suite(test_task_shim,
+			 ztest_unit_test(test_crc8_known_data));
+	ztest_run_test_suite(test_task_shim);
+}

zephyr/test/crc/prj.conf

@@ -0,0 +1,5 @@
+# Copyright 2020 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+CONFIG_ZTEST=y