spi: microchip-core: fix init function not setting the master and motorola modes

mchp_corespi_init() reads the CONTROL register, sets the master and
motorola bits, but doesn't write the value back to the register. The
function also doesn't ensure the controller is disabled at the start,
which may present a problem if the controller was used by an
earlier boot stage as some settings (including the mode) can only be
modified while the controller is disabled.

Fixes: 9ac8d176 ("spi: add support for microchip fpga spi controllers")
Signed-off-by: Steve Wilkins <steve.wilkins@raymarine.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/20240715-designing-thus-05f7c26e1da7@wendySigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-microchip-core.c

@@ -295,17 +295,13 @@ static void mchp_corespi_init(struct spi_controller *host, struct mchp_corespi *
 	unsigned long clk_hz;
 	u32 control = mchp_corespi_read(spi, REG_CONTROL);
 
-	control |= CONTROL_MASTER;
+	control &= ~CONTROL_ENABLE;
+	mchp_corespi_write(spi, REG_CONTROL, control);
 
+	control |= CONTROL_MASTER;
 	control &= ~CONTROL_MODE_MASK;
 	control |= MOTOROLA_MODE;
 
-	mchp_corespi_set_framesize(spi, DEFAULT_FRAMESIZE);
-
-	/* max. possible spi clock rate is the apb clock rate */
-	clk_hz = clk_get_rate(spi->clk);
-	host->max_speed_hz = clk_hz;
-
 	/*
 	 * The controller must be configured so that it doesn't remove Chip
 	 * Select until the entire message has been transferred, even if at
@@ -314,11 +310,16 @@ static void mchp_corespi_init(struct spi_controller *host, struct mchp_corespi *
 	 * BIGFIFO mode is also enabled, which sets the fifo depth to 32 frames
 	 * for the 8 bit transfers that this driver uses.
 	 */
-	control = mchp_corespi_read(spi, REG_CONTROL);
 	control |= CONTROL_SPS | CONTROL_BIGFIFO;
 
 	mchp_corespi_write(spi, REG_CONTROL, control);
 
+	mchp_corespi_set_framesize(spi, DEFAULT_FRAMESIZE);
+
+	/* max. possible spi clock rate is the apb clock rate */
+	clk_hz = clk_get_rate(spi->clk);
+	host->max_speed_hz = clk_hz;
+
 	mchp_corespi_enable_ints(spi);
 
 	/*