[RFC/PATCH 2/2] driver: spi: Add quad spi read support

[Sourav Poddar <sourav.poddar@ti.com>]

Since, qspi controller uses quad read.

Configuring the command register, if the transfer of data needs
dual or quad lines.

This patch has been done on top of the following patch[1], which is just the
basic idea of adding dual/quad support in spi framework.
$subject patch will undergo changes once the ongoing discussion in the
community is freezed.

This patch is posted to demonstrate how patch 1 of the series will support
quad read.

[1]: http://comments.gmane.org/gmane.linux.kernel.spi.devel/14047

Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
---
 drivers/spi/spi-ti-qspi.c |   22 ++++++++++++++++------
 1 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/spi/spi-ti-qspi.c b/drivers/spi/spi-ti-qspi.c
index 73a1675..fac1722 100644
--- a/drivers/spi/spi-ti-qspi.c
+++ b/drivers/spi/spi-ti-qspi.c
@@ -265,18 +265,30 @@ static int qspi_write_msg(struct ti_qspi *qspi, struct spi_transfer *t)
 static int qspi_read_msg(struct ti_qspi *qspi, struct spi_transfer *t)
 {
 	int wlen, count, ret;
+	unsigned cmd = qspi->cmd;
 
 	count = t->len;
 	wlen = t->bits_per_word;
 
+	switch (t->bitwidth) {
+	case SPI_BITWIDTH_QUAD:
+		cmd |= QSPI_RD_QUAD;
+		break;
+	case SPI_BITWIDTH_DUAL:
+		cmd |= QSPI_RD_DUAL;
+		break;
+	case SPI_BITWIDTH_SINGLE:
+	default:
+		cmd |= QSPI_RD_SNGL;
+	}
+
 	if (wlen == 8) {
 		u8        *rxbuf;
 		rxbuf = t->rx_buf;
 		do {
 			dev_dbg(qspi->dev, "rx cmd %08x dc %08x\n",
 				qspi->cmd | QSPI_RD_SNGL, qspi->dc);
-			ti_qspi_write(qspi, qspi->cmd | QSPI_RD_SNGL,
-				QSPI_SPI_CMD_REG);
+			ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG);
 			ret = wait_for_completion_timeout(&qspi->transfer_complete,
 				QSPI_COMPLETION_TIMEOUT);
 			if (ret == 0) {
@@ -294,8 +306,7 @@ static int qspi_read_msg(struct ti_qspi *qspi, struct spi_transfer *t)
 		do {
 			dev_dbg(qspi->dev, "rx cmd %08x dc %08x\n",
 				qspi->cmd | QSPI_RD_SNGL, qspi->dc);
-			ti_qspi_write(qspi, qspi->cmd | QSPI_RD_SNGL,
-				QSPI_SPI_CMD_REG);
+			ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG);
 			ret = wait_for_completion_timeout(&qspi->transfer_complete,
 					QSPI_COMPLETION_TIMEOUT);
 			if (ret == 0) {
@@ -313,8 +324,7 @@ static int qspi_read_msg(struct ti_qspi *qspi, struct spi_transfer *t)
 		do {
 			dev_dbg(qspi->dev, "rx cmd %08x dc %08x\n",
 				qspi->cmd | QSPI_RD_SNGL, qspi->dc);
-			ti_qspi_write(qspi, qspi->cmd | QSPI_RD_SNGL,
-				QSPI_SPI_CMD_REG);
+			ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG);
 			ret = wait_for_completion_timeout(&qspi->transfer_complete,
 					QSPI_COMPLETION_TIMEOUT);
 			if (ret == 0) {
-- 
1.7.1