spi: Fix OCTAL mode support

Add OCTAL mode support.
Issue detected using "--octal" spidev_test's option.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Link: https://msgid.link/r/20240618132951.2743935-4-patrice.chotard@foss.st.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Patrice Chotard

drivers/spi/spi.c

@@ -4156,7 +4156,8 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 				return -EINVAL;
 			if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
 				xfer->tx_nbits != SPI_NBITS_DUAL &&
-				xfer->tx_nbits != SPI_NBITS_QUAD)
+				xfer->tx_nbits != SPI_NBITS_QUAD &&
+				xfer->tx_nbits != SPI_NBITS_OCTAL)
 				return -EINVAL;
 			if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
 				!(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
@@ -4171,7 +4172,8 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 				return -EINVAL;
 			if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
 				xfer->rx_nbits != SPI_NBITS_DUAL &&
-				xfer->rx_nbits != SPI_NBITS_QUAD)
+				xfer->rx_nbits != SPI_NBITS_QUAD &&
+				xfer->rx_nbits != SPI_NBITS_OCTAL)
 				return -EINVAL;
 			if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
 				!(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))

include/linux/spi/spi.h

@@ -1085,12 +1085,13 @@ struct spi_transfer {
 	unsigned	dummy_data:1;
 	unsigned	cs_off:1;
 	unsigned	cs_change:1;
-	unsigned	tx_nbits:3;
-	unsigned	rx_nbits:3;
+	unsigned	tx_nbits:4;
+	unsigned	rx_nbits:4;
 	unsigned	timestamped:1;
 #define	SPI_NBITS_SINGLE	0x01 /* 1-bit transfer */
 #define	SPI_NBITS_DUAL		0x02 /* 2-bit transfer */
 #define	SPI_NBITS_QUAD		0x04 /* 4-bit transfer */
+#define	SPI_NBITS_OCTAL	0x08 /* 8-bit transfer */
 	u8		bits_per_word;
 	struct spi_delay	delay;
 	struct spi_delay	cs_change_delay;