spi: spi-zynq-qspi: Handle odd number of byte in dual parallel mode

In dual parallel configuration, all commands are sent to both flash
devices but the data is split into odd and even bits between lower and
upper flash. So the read/write data length should be of even length.
When odd number of data bytes are requested to be transmitted, the driver
adds an extra byte to make the data length even.

Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@xilinx.com>

drivers/spi/spi-zynq-qspi.c

@@ -131,6 +131,8 @@
  * @rx_bytes:		Number of bytes left to receive
  * @data_completion:	completion structure
  * @is_dual:		Flag to indicate whether dual flash memories are used
+ * @is_stripe:		Flag to indicate if data needs to be split between flashes
+ *			(Used in dual parallel configuration)
  */
 struct zynq_qspi {
 	struct device *dev;
@@ -144,6 +146,7 @@ struct zynq_qspi {
 	int rx_bytes;
 	struct completion data_completion;
 	u32 is_dual;
+	bool is_stripe;
 };
 
 /*
@@ -248,11 +251,15 @@ static bool zynq_qspi_supports_op(struct spi_mem *mem,
 static void zynq_qspi_rxfifo_op(struct zynq_qspi *xqspi, unsigned int size)
 {
 	u32 data;
+	unsigned int xsize;
 
 	data = zynq_qspi_read(xqspi, ZYNQ_QSPI_RXD_OFFSET);
 
 	if (xqspi->rxbuf) {
-		memcpy(xqspi->rxbuf, ((u8 *)&data) + 4 - size, size);
+		xsize = size;
+		if (xqspi->is_dual && xqspi->is_stripe && (size % 2))
+			xsize++;
+		memcpy(xqspi->rxbuf, ((u8 *)&data) + 4 - xsize, size);
 		xqspi->rxbuf += size;
 	}
 
@@ -272,6 +279,7 @@ static void zynq_qspi_txfifo_op(struct zynq_qspi *xqspi, unsigned int size)
 		ZYNQ_QSPI_TXD_00_01_OFFSET, ZYNQ_QSPI_TXD_00_10_OFFSET,
 		ZYNQ_QSPI_TXD_00_11_OFFSET, ZYNQ_QSPI_TXD_00_00_OFFSET };
 	u32 data;
+	unsigned int xsize;
 
 	if (xqspi->txbuf) {
 		data = 0xffffffff;
@@ -282,7 +290,11 @@ static void zynq_qspi_txfifo_op(struct zynq_qspi *xqspi, unsigned int size)
 	}
 
 	xqspi->tx_bytes -= size;
-	zynq_qspi_write(xqspi, offset[size - 1], data);
+	xsize = size;
+	if (xqspi->is_dual && xqspi->is_stripe && (size % 2))
+		xsize++;
+
+	zynq_qspi_write(xqspi, offset[xsize - 1], data);
 }
 
 /**
@@ -595,6 +607,8 @@ static int zynq_qspi_exec_mem_op(struct spi_mem *mem,
 	}
 
 	if (op->data.nbytes) {
+		if (xqspi->is_dual)
+			xqspi->is_stripe = update_stripe(op);
 		reinit_completion(&xqspi->data_completion);
 		if (op->data.dir == SPI_MEM_DATA_OUT) {
 			xqspi->txbuf = (u8 *)op->data.buf.out;
@@ -615,6 +629,9 @@ static int zynq_qspi_exec_mem_op(struct spi_mem *mem,
 							       msecs_to_jiffies(1000)))
 			err = -ETIMEDOUT;
 	}
+	if (xqspi->is_stripe)
+		xqspi->is_stripe = false;
+
 	zynq_qspi_chipselect(mem->spi, false);
 
 	return err;