make spi_init return baud rate set

src/rp2_common/hardware_spi/include/hardware/spi.h

@@ -102,14 +102,14 @@ typedef enum {
  * Puts the SPI into a known state, and enable it. Must be called before other
  * functions.
  *
- * \param spi SPI instance specifier, either \ref spi0 or \ref spi1
- * \param baudrate Baudrate required in Hz
+ * \note There is no guarantee that the baudrate requested can be achieved exactly; the nearest will be chosen
+ * and returned
  *
- * \note There is no guarantee that the baudrate requested will be possible, the nearest will be chosen,
- * and this function does not return any indication of this. You can use the \ref spi_set_baudrate function
- * which will return the actual baudrate selected if this is important.
+ * \param spi SPI instance specifier, either \ref spi0 or \ref spi1
+ * \param baudrate Baudrate requested in Hz
+ * \return the actual baud rate set
  */
-void spi_init(spi_inst_t *spi, uint baudrate);
+uint spi_init(spi_inst_t *spi, uint baudrate);
 
 /*! \brief Deinitialise SPI instances
  *  \ingroup hardware_spi

src/rp2_common/hardware_spi/spi.c

@@ -18,18 +18,19 @@ static inline void spi_unreset(spi_inst_t *spi) {
     unreset_block_wait(spi == spi0 ? RESETS_RESET_SPI0_BITS : RESETS_RESET_SPI1_BITS);
 }
 
-void spi_init(spi_inst_t *spi, uint baudrate) {
+uint spi_init(spi_inst_t *spi, uint baudrate) {
     spi_reset(spi);
     spi_unreset(spi);
 
-    (void) spi_set_baudrate(spi, baudrate);
+    uint baud = spi_set_baudrate(spi, baudrate);
     spi_set_format(spi, 8, SPI_CPOL_0, SPI_CPHA_0, SPI_MSB_FIRST);
     // Always enable DREQ signals -- harmless if DMA is not listening
     hw_set_bits(&spi_get_hw(spi)->dmacr, SPI_SSPDMACR_TXDMAE_BITS | SPI_SSPDMACR_RXDMAE_BITS);
     spi_set_format(spi, 8, SPI_CPOL_0, SPI_CPHA_0, SPI_MSB_FIRST);
 
     // Finally enable the SPI
     hw_set_bits(&spi_get_hw(spi)->cr1, SPI_SSPCR1_SSE_BITS);
+    return baud;
 }
 
 void spi_deinit(spi_inst_t *spi) {