[PATCH 08/11] spi: dw: update buffer for enhanced spi mode

[Sudip Mukherjee <sudip.mukherjee@sifive.com>]

In enhanced spi mode we will be writing the address to a single FIFO
location instead of writing to multiple FIFOs in the standard SPI mode.
Save the cmd and address bytes in the buffer accordingly.

Signed-off-by: Sudip Mukherjee <sudip.mukherjee@sifive.com>
---
 drivers/spi/spi-dw-core.c | 55 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 7 deletions(-)

diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
index 8cb30540ad5b..2564a2276572 100644
--- a/drivers/spi/spi-dw-core.c
+++ b/drivers/spi/spi-dw-core.c
@@ -520,7 +520,8 @@ static bool dw_spi_supports_mem_op(struct spi_mem *mem,
 	return spi_mem_default_supports_op(mem, op);
 }
 
-static int dw_spi_init_mem_buf(struct dw_spi *dws, const struct spi_mem_op *op)
+static int dw_spi_init_mem_buf(struct dw_spi *dws, const struct spi_mem_op *op,
+			       bool enhanced_spi)
 {
 	unsigned int i, j, len;
 	u8 *out;
@@ -548,17 +549,57 @@ static int dw_spi_init_mem_buf(struct dw_spi *dws, const struct spi_mem_op *op)
 	 */
 	for (i = 0; i < op->cmd.nbytes; ++i)
 		out[i] = DW_SPI_GET_BYTE(op->cmd.opcode, op->cmd.nbytes - i - 1);
-	for (j = 0; j < op->addr.nbytes; ++i, ++j)
-		out[i] = DW_SPI_GET_BYTE(op->addr.val, op->addr.nbytes - j - 1);
-	for (j = 0; j < op->dummy.nbytes; ++i, ++j)
-		out[i] = 0x0;
+
+	if (enhanced_spi) {
+		/*
+		 * Fill the remaining spaces of dws->reg_io_width bytes
+		 * size register with zero for cmd.
+		 */
+		for (; i < dws->reg_io_width; ++i)
+			out[i] = 0;
+		/*
+		 * Copy the address bytes in dws->reg_io_width bytes size
+		 * register and fill remaining spaces with zero.
+		 */
+		for (j = op->addr.nbytes; j > 0; ++i, --j)
+			out[i] = DW_SPI_GET_BYTE(op->addr.val, op->addr.nbytes - j);
+		for (j = op->addr.nbytes; j < dws->reg_io_width; ++i, ++j)
+			out[i] = 0;
+	} else {
+		for (j = 0; j < op->addr.nbytes; ++i, ++j)
+			out[i] = DW_SPI_GET_BYTE(op->addr.val, op->addr.nbytes - j - 1);
+	}
+
+	if (!enhanced_spi) {
+		/*
+		 * dummy bytes are not needed in enhanced mode as
+		 * wait_cycles specified as number of SPI clock cycles
+		 * between control frames transmit and data reception
+		 * will be mentioned in enhanced spi mode.
+		 */
+		for (j = 0; j < op->dummy.nbytes; ++i, ++j)
+			out[i] = 0x0;
+	}
 
 	if (op->data.dir == SPI_MEM_DATA_OUT)
 		memcpy(&out[i], op->data.buf.out, op->data.nbytes);
 
 	dws->n_bytes = 1;
 	dws->tx = out;
-	dws->tx_len = len;
+
+	if (enhanced_spi) {
+		/*
+		 * In enhanced mode cmd will be one FIFO and address
+		 * will be one more FIFO.
+		 */
+		dws->tx_len = 1;
+		if (op->addr.nbytes)
+			dws->tx_len += 1;
+		if (op->data.dir == SPI_MEM_DATA_OUT)
+			dws->tx_len += op->data.nbytes;
+	} else {
+		dws->tx_len = len;
+	}
 	if (op->data.dir == SPI_MEM_DATA_IN) {
 		dws->rx = op->data.buf.in;
 		dws->rx_len = op->data.nbytes;
@@ -744,7 +785,7 @@ static int dw_spi_exec_mem_op(struct spi_mem *mem, const struct spi_mem_op *op)
 	 * Collect the outbound data into a single buffer to speed the
 	 * transmission up at least on the initial stage.
 	 */
-	ret = dw_spi_init_mem_buf(dws, op);
+	ret = dw_spi_init_mem_buf(dws, op, enhanced_spi);
 	if (ret)
 		return ret;
 
-- 
2.30.2