arch/arm/src/stm32h7: Add the spi slave bus control driver

This is a work in progress, and now only serves as
DMA enabled simplex RX-only mode bus controller

Signed-off-by: Jukka Laitinen <jukka.laitinen@intel.com>

arch/arm/src/stm32h7/Make.defs

@@ -180,6 +180,10 @@ ifeq ($(CONFIG_STM32H7_SPI),y)
 CHIP_CSRCS += stm32_spi.c
 endif
 
+ifeq ($(CONFIG_SPI_SLAVE),y)
+CHIP_CSRCS += stm32_spi_slave.c
+endif
+
 ifeq ($(CONFIG_STM32H7_SDMMC),y)
 CHIP_CSRCS += stm32_sdmmc.c
 endif

arch/arm/src/stm32h7/stm32_spi.h

@@ -82,6 +82,22 @@ struct spi_dev_s; /* Forward reference */
 
 FAR struct spi_dev_s *stm32_spibus_initialize(int bus);
 
+/*****************************************************************************
+ * Name: stm32_spi_slave_initialize
+ *
+ * Description:
+ *   Initialize the selected SPI bus for slave operation
+ *
+ * Input Parameters:
+ *   bus number
+ *
+ * Returned Value:
+ *   Valid SPI device structure reference on succcess; a NULL on failure
+ *
+ *****************************************************************************/
+
+FAR struct spi_sctrlr_s *stm32_spi_slave_initialize(int bus);
+
 /*****************************************************************************
  * Name:  stm32_spi1/2/...select and stm32_spi1/2/...status
  *