spi: Implement spi_set_speed
This function is already defined in spi.h but no implementation of it
currently exists in the tree. The implementation is based on the static
function spi_set_speed_mode(). The function prototype is modified so
that an success or error condition can be returned to the caller.
Signed-off-by: Paul Barker <paul.barker@sancloud.com>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/include/spi.h b/include/spi.h
index 9a8c1fb..1bc18e6 100644
--- a/include/spi.h
+++ b/include/spi.h
@@ -352,8 +352,10 @@
* This sets a new speed to be applied for next spi_xfer().
* @slave: The SPI slave
* @hz: The transfer speed
+ *
+ * Returns: 0 on success, or a negative value on error.
*/
-void spi_set_speed(struct spi_slave *slave, uint hz);
+int spi_set_speed(struct spi_slave *slave, uint hz);
/**
* Write 8 bits, then read 8 bits.