sdm845: qspi: Add Dual SPI support

This patch adds support for the Dual SPI feature (SDR 2-bit in Qualcomm
terminology) to the QSPI controller.

Change-Id: I7aed2ccd9627f5de5dd760b418f74d56d2c031d3
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33284
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/qualcomm/sdm845/include/soc/qspi.h

@@ -116,4 +116,6 @@ int sdm845_setup_bus(const struct spi_slave *slave);
 void sdm845_release_bus(const struct spi_slave *slave);
 int sdm845_xfer(const struct spi_slave *slave, const void *dout,
 		size_t out_bytes, void *din, size_t in_bytes);
+int sdm845_xfer_dual(const struct spi_slave *slave, const void *dout,
+		     size_t out_bytes, void *din, size_t in_bytes);
 #endif /* __SOC_QUALCOMM_SDM845_QSPI_H__ */

src/soc/qualcomm/sdm845/qspi.c

@@ -277,11 +277,9 @@ void sdm845_release_bus(const struct spi_slave *slave)
 	cs_change(CS_DEASSERT);
 }
 
-int sdm845_xfer(const struct spi_slave *slave, const void *dout,
+static int xfer(enum qspi_mode mode, const void *dout, size_t out_bytes,
-		       size_t out_bytes, void *din, size_t in_bytes)
+		void *din, size_t in_bytes)
 {
-	enum qspi_mode mode = SDR_1BIT;
-
 	if ((out_bytes && !dout) || (in_bytes && !din) ||
 		(in_bytes && out_bytes)) {
 		return -1;
@@ -294,3 +292,15 @@ int sdm845_xfer(const struct spi_slave *slave, const void *dout,
 
 	return 0;
 }
+
+int sdm845_xfer(const struct spi_slave *slave, const void *dout,
+		size_t out_bytes, void *din, size_t in_bytes)
+{
+	return xfer(SDR_1BIT, dout, out_bytes, din, in_bytes);
+}
+
+int sdm845_xfer_dual(const struct spi_slave *slave, const void *dout,
+		     size_t out_bytes, void *din, size_t in_bytes)
+{
+	return xfer(SDR_2BIT, dout, out_bytes, din, in_bytes);
+}

src/soc/qualcomm/sdm845/spi.c

@@ -21,6 +21,7 @@ static const struct spi_ctrlr spi_ctrlr = {
 	.claim_bus = sdm845_claim_bus,
 	.release_bus = sdm845_release_bus,
 	.xfer = sdm845_xfer,
+	.xfer_dual = sdm845_xfer_dual,
 	.max_xfer_size = QSPI_MAX_PACKET_COUNT,
 };