greybus: spi: add rdwr field to transfer descriptor

Add read and/or write field to transfer descriptor to make it possible
to identify the type of transfer.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/greybus_protocols.h

@@ -695,6 +695,9 @@ struct gb_spi_transfer {
 	__le16		delay_usecs;
 	__u8		cs_change;
 	__u8		bits_per_word;
+	__u8		rdwr;
+#define GB_SPI_XFER_READ	0x01
+#define GB_SPI_XFER_WRITE	0x02
 } __packed;
 
 struct gb_spi_transfer_request {

drivers/staging/greybus/spi.c

@@ -107,13 +107,16 @@ gb_spi_operation_create(struct gb_connection *connection,
 		gb_xfer->delay_usecs = cpu_to_le16(xfer->delay_usecs);
 		gb_xfer->cs_change = xfer->cs_change;
 		gb_xfer->bits_per_word = xfer->bits_per_word;
-		gb_xfer++;
 
 		/* Copy tx data */
 		if (xfer->tx_buf) {
 			memcpy(tx_data, xfer->tx_buf, xfer->len);
 			tx_data += xfer->len;
+			gb_xfer->rdwr |= GB_SPI_XFER_WRITE;
 		}
+		if (xfer->rx_buf)
+			gb_xfer->rdwr |= GB_SPI_XFER_READ;
+		gb_xfer++;
 	}
 
 	return operation;