[PATCH 4/5] spi: Check that Quad/Dual is half duplex

[Geert Uytterhoeven <geert@linux-m68k.org>]

From: Geert Uytterhoeven <geert+renesas@linux-m68k.org>

Quad and Dual SPI Transfers use all available data lines (incl. MOSI/MISO),
hence they must be half duplex. Add a check that verify that.

Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
---
I think this check is done nowhere else. Please correct me if I missed it.

 drivers/spi/spi.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 7f77f82bf95e..4afcdb4851fa 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1672,6 +1672,7 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 		/* check transfer tx/rx_nbits:
 		 * 1. check the value matches one of single, dual and quad
 		 * 2. check tx/rx_nbits match the mode in spi_device
+		 * 3. check dual or quad is half duplex
 		 */
 		if (xfer->tx_buf) {
 			if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
@@ -1684,6 +1685,8 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 			if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
 				!(spi->mode & SPI_TX_QUAD))
 				return -EINVAL;
+			if (xfer->tx_nbits > SPI_NBITS_SINGLE && xfer->rx_buf)
+				return -EINVAL;
 		}
 		/* check transfer rx_nbits */
 		if (xfer->rx_buf) {
@@ -1697,6 +1700,8 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 			if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
 				!(spi->mode & SPI_RX_QUAD))
 				return -EINVAL;
+			if (xfer->rx_nbits > SPI_NBITS_SINGLE && xfer->tx_buf)
+				return -EINVAL;
 		}
 	}
 
-- 
1.7.9.5