spi: Add check for 8-bit transfer with 8 IO mode support

commit 710505212e3272396394f8cf78e3ddfd05df3f22 upstream.

The current SPI framework does not verify if the SPI device supports
8 IO mode when doing an 8-bit transfer. This patch adds a check to
ensure that if the transfer tx_nbits or rx_nbits is 8, the SPI mode must
support 8 IO. If not, an error is returned, preventing undefined behavior.

Fixes: d6a711a ("spi: Fix OCTAL mode support")
Cc: [email protected]
Signed-off-by: Cheng Ming Lin <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Mark Brown <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
(cherry picked from commit 82b29ee8ba906b651950ea73711595136478b6b6)

Author: zmlin1998

drivers/spi/spi.c

@@ -4084,10 +4084,13 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 				xfer->tx_nbits != SPI_NBITS_OCTAL)
 				return -EINVAL;
 			if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
-				!(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
+				!(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL)))
 				return -EINVAL;
 			if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
-				!(spi->mode & SPI_TX_QUAD))
+				!(spi->mode & (SPI_TX_QUAD | SPI_TX_OCTAL)))
+				return -EINVAL;
+			if ((xfer->tx_nbits == SPI_NBITS_OCTAL) &&
+				!(spi->mode & SPI_TX_OCTAL))
 				return -EINVAL;
 		}
 		/* Check transfer rx_nbits */
@@ -4100,10 +4103,13 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 				xfer->rx_nbits != SPI_NBITS_OCTAL)
 				return -EINVAL;
 			if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
-				!(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
+				!(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL)))
 				return -EINVAL;
 			if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
-				!(spi->mode & SPI_RX_QUAD))
+				!(spi->mode & (SPI_RX_QUAD | SPI_RX_OCTAL)))
+				return -EINVAL;
+			if ((xfer->rx_nbits == SPI_NBITS_OCTAL) &&
+				!(spi->mode & SPI_RX_OCTAL))
 				return -EINVAL;
 		}