spi: spi-fsl-dspi: Enable extended SPI mode

Set the XSPI bit for devices configured for XSPI mode (currently LS1021A),
and thereby switch to extended SPI mode, allowing for SPI transfers using
from 4 to 32 bits per word instead of 4 to 16 bits per word.

Signed-off-by: Esben Haabendal <eha@deif.com>
Acked-by: Martin Hundebøll <martin@geanix.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-fsl-dspi.c

@@ -46,6 +46,7 @@
 #define SPI_MCR_PCSIS		(0x3F << 16)
 #define SPI_MCR_CLR_TXF	(1 << 11)
 #define SPI_MCR_CLR_RXF	(1 << 10)
+#define SPI_MCR_XSPI		(1 << 3)
 
 #define SPI_TCR			0x08
 #define SPI_TCR_GET_TCNT(x)	(((x) & 0xffff0000) >> 16)
@@ -968,7 +969,8 @@ static const struct regmap_config dspi_xspi_regmap_config[] = {
 
 static void dspi_init(struct fsl_dspi *dspi)
 {
-	regmap_write(dspi->regmap, SPI_MCR, SPI_MCR_MASTER | SPI_MCR_PCSIS);
+	regmap_write(dspi->regmap, SPI_MCR, SPI_MCR_MASTER | SPI_MCR_PCSIS |
+		     (dspi->devtype_data->xspi_mode ? SPI_MCR_XSPI : 0));
 	regmap_write(dspi->regmap, SPI_SR, SPI_SR_CLEAR);
 	if (dspi->devtype_data->xspi_mode)
 		regmap_write(dspi->regmap, SPI_CTARE(0),