[PATCH v6 1/7] spi: add support for octal mode I/O data transfer

[Yogesh Narayan Gaur <yogeshnarayan.gaur@nxp.com>]

Add flags for Octal mode I/O data transfer
Required for the SPI controller which can do the data transfer (TX/RX)
on 8 data lines e.g. NXP FlexSPI controller.
 SPI_TX_OCTAL: transmit with 8 wires
 SPI_RX_OCTAL: receive with 8 wires

Signed-off-by: Yogesh Narayan Gaur <yogeshnarayan.gaur@nxp.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
---
Changes for v6:
- Correct S-o-b tag with full author name as 'Yogesh Narayan Gaur'.
Changes for v5:
- Modified string 'octo' with 'octal'.
Changes for v4:
- Rebase on top of v4.20-rc2
Changes for v3:
- Modified string 'octal' with 'octo'.
- Add octo mode support in spi_setup().
Changes for v2:
- Incorporated review comments of Boris.

 drivers/spi/spi.c       | 12 ++++++++++--
 include/linux/spi/spi.h |  4 +++-
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 6ca5940..95249b8 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1617,6 +1617,9 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
 		case 4:
 			spi->mode |= SPI_TX_QUAD;
 			break;
+		case 8:
+			spi->mode |= SPI_TX_OCTAL;
+			break;
 		default:
 			dev_warn(&ctlr->dev,
 				"spi-tx-bus-width %d not supported\n",
@@ -1635,6 +1638,9 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
 		case 4:
 			spi->mode |= SPI_RX_QUAD;
 			break;
+		case 8:
+			spi->mode |= SPI_RX_OCTAL;
+			break;
 		default:
 			dev_warn(&ctlr->dev,
 				"spi-rx-bus-width %d not supported\n",
@@ -2823,7 +2829,8 @@ int spi_setup(struct spi_device *spi)
 	/* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
 	 */
 	if ((spi->mode & SPI_3WIRE) && (spi->mode &
-		(SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
+		(SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL |
+		 SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL)))
 		return -EINVAL;
 	/* help drivers fail *cleanly* when they need options
 	 * that aren't supported with their current controller
@@ -2832,7 +2839,8 @@ int spi_setup(struct spi_device *spi)
 	 */
 	bad_bits = spi->mode & ~(spi->controller->mode_bits | SPI_CS_WORD);
 	ugly_bits = bad_bits &
-		    (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD);
+		    (SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL |
+		     SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL);
 	if (ugly_bits) {
 		dev_warn(&spi->dev,
 			 "setup: ignoring unsupported mode bits %x\n",
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 6be77fa..0c1ca5d 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -154,7 +154,9 @@ struct spi_device {
 #define	SPI_TX_QUAD	0x200			/* transmit with 4 wires */
 #define	SPI_RX_DUAL	0x400			/* receive with 2 wires */
 #define	SPI_RX_QUAD	0x800			/* receive with 4 wires */
-#define SPI_CS_WORD	0x1000			/* toggle cs after each word */
+#define	SPI_CS_WORD	0x1000			/* toggle cs after each word */
+#define	SPI_TX_OCTAL	0x2000			/* transmit with 8 wires */
+#define	SPI_RX_OCTAL	0x4000			/* receive with 8 wires */
 	int			irq;
 	void			*controller_state;
 	void			*controller_data;
-- 
2.7.4