spi: spi-mem: add support for octal mode I/O data transfer

Add support for octal mode I/O data transfer in spi-mem framework.
Signed-off-by: Yogesh Gaur <yogeshnarayan.gaur@nxp.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-mem.c

@@ -12,7 +12,7 @@
 
 #include "internals.h"
 
-#define SPI_MEM_MAX_BUSWIDTH		4
+#define SPI_MEM_MAX_BUSWIDTH		8
 
 /**
  * spi_controller_dma_map_mem_op_data() - DMA-map the buffer attached to a
@@ -121,6 +121,13 @@ static int spi_check_buswidth_req(struct spi_mem *mem, u8 buswidth, bool tx)
 
 		break;
 
+	case 8:
+		if ((tx && (mode & SPI_TX_OCTAL)) ||
+		    (!tx && (mode & SPI_RX_OCTAL)))
+			return 0;
+
+		break;
+
 	default:
 		break;
 	}