[PATCH] bsps/stm32h7: clarify license of stm32h7b3i-dk BSP variant

[Karel Gardas]

The system_stm32h7xx.c file provided in the boards/stm/stm32h7b3i-dk
subdirectory needs a bit of clarification as it references "root directory"
in its license comment and it's not clear where this points out.
Let's add clarification comment about it and also based on it
and resulting license let's add SPDX license identifier.
---
 .../stm/stm32h7b3i-dk/system_stm32h7xx.c      | 46 +++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/bsps/arm/stm32h7/boards/stm/stm32h7b3i-dk/system_stm32h7xx.c b/bsps/arm/stm32h7/boards/stm/stm32h7b3i-dk/system_stm32h7xx.c
index db11aa19b1..44c13beaf2 100644
--- a/bsps/arm/stm32h7/boards/stm/stm32h7b3i-dk/system_stm32h7xx.c
+++ b/bsps/arm/stm32h7/boards/stm/stm32h7b3i-dk/system_stm32h7xx.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /**
   ******************************************************************************
   * @file    system_stm32h7xx.c
@@ -31,6 +32,51 @@
   *
   ******************************************************************************
   */
+/*
+ * RTEMS committer clarification comment on license above:
+ *
+ * This file comes from STM32CubeH7 project from its Projects
+ * subdirectory. There is Templates subdirectory per every supported
+ * BSP there. The Templates contains the file. In our case the file is
+ * here:
+ * https://github.com/STMicroelectronics/STM32CubeH7/blob/master/Projects/STM32H7B3I-DK/Templates/Src/system_stm32h7xx.c
+ *
+ * When we go up in the directory tree starting from the file, we find
+ * out that the "root directory" in the sense of license claim above is Templates
+ * directory here:
+ * https://github.com/STMicroelectronics/STM32CubeH7/tree/master/Projects/STM32H7B3I-DK/Templates
+ *
+ * This directory contains LICENSE.md file with a following license text:
+ *
+ * Copyright 2019 STMicroelectronics.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation and/or
+ * other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its contributors
+ * may be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
 
 /** @addtogroup CMSIS
   * @{
-- 
2.25.1