spi: spi-fsl-dspi: Don't access reserved fields in SPI_MCR

The SPI_MCR_PCSIS macro assumes that the controller has a number of chip
select signals equal to 6. That is not always the case, but actually is
described through the driver-specific "spi-num-chipselects" device tree
binding. LS1028A for example only has 4 chip selects.

Don't write to the upper bits of the PCSIS field, which are reserved in
the reference manual.

Fixes: 349ad66c0ab0 ("spi:Add Freescale DSPI driver for Vybrid VF610 platform")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20200318001603.9650-2-olteanv@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index 50e3382..6ca3588 100644 (file)
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -22,7 +22,7 @@
 
 #define SPI_MCR                                0x00
 #define SPI_MCR_MASTER                 BIT(31)
-#define SPI_MCR_PCSIS                  (0x3F << 16)
+#define SPI_MCR_PCSIS(x)               ((x) << 16)
 #define SPI_MCR_CLR_TXF                        BIT(11)
 #define SPI_MCR_CLR_RXF                        BIT(10)
 #define SPI_MCR_XSPI                   BIT(3)
@@ -1200,7 +1200,10 @@ static const struct regmap_config dspi_xspi_regmap_config[] = {
 
 static void dspi_init(struct fsl_dspi *dspi)
 {
-       unsigned int mcr = SPI_MCR_PCSIS;
+       unsigned int mcr;
+
+       /* Set idle states for all chip select signals to high */
+       mcr = SPI_MCR_PCSIS(GENMASK(dspi->ctlr->num_chipselect - 1, 0));
 
        if (dspi->devtype_data->trans_mode == DSPI_XSPI_MODE)
                mcr |= SPI_MCR_XSPI;