spi: stm32_qspi: Add QSPI support

Add QSPI support (limited to read interface).
Implements the memory map and indirect modes.
Low level driver based on SPI-MEM operations.

Change-Id: Ied698e6de3c17d977f8b497c81f2e4a0a27c0961
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Christophe Kerello <christophe.kerello@st.com>
diff --git a/include/drivers/st/stm32_qspi.h b/include/drivers/st/stm32_qspi.h
new file mode 100644
index 0000000..f47fca4
--- /dev/null
+++ b/include/drivers/st/stm32_qspi.h
@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) 2019, STMicroelectronics - All Rights Reserved
+ *
+ * SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
+ */
+
+#ifndef STM32_QSPI_H
+#define STM32_QSPI_H
+
+int stm32_qspi_init(void);
+
+#endif /* STM32_QSPI_H */