[PATCH v2 13/15] spi: dw: detect enhanced spi mode

[Sudip Mukherjee <sudip.mukherjee@xxxxxxxxxx>]

All the SSI controllers supporting enhanced spi modes might not support
all the three dual or quad or octal modes. Detect the modes that are
supported and finally enable the DW_SPI_CAP_EMODE capability which will
start using all the enhanced spi functions that has been added.

Signed-off-by: Sudip Mukherjee <sudip.mukherjee@xxxxxxxxxx>
---
 drivers/spi/spi-dw-core.c | 68 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 66 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
index cef56acd8d8fd..9e806d5878beb 100644
--- a/drivers/spi/spi-dw-core.c
+++ b/drivers/spi/spi-dw-core.c
@@ -1143,6 +1143,69 @@ static void dw_spi_hw_init(struct device *dev, struct dw_spi *dws)
 		dw_writel(dws, DW_SPI_CS_OVERRIDE, 0xF);
 }
 
+static u16 detect_enh_mode(struct dw_spi *dws)
+{
+	u16 mode = 0;
+	u32 tmp_spi_ctrlr0, tmp_ctrlr0, tmpdual, tmpquad, tmpoct;
+
+	if (dw_spi_ver_is_ge(dws, HSSI, 103A)) {
+		tmpdual = FIELD_PREP(DW_HSSI_CTRLR0_SPI_FRF_MASK,
+				     DW_SPI_CTRLR0_SPI_FRF_DUAL_SPI);
+		tmpquad = FIELD_PREP(DW_HSSI_CTRLR0_SPI_FRF_MASK,
+				     DW_SPI_CTRLR0_SPI_FRF_QUAD_SPI);
+		tmpoct = FIELD_PREP(DW_HSSI_CTRLR0_SPI_FRF_MASK,
+				    DW_SPI_CTRLR0_SPI_FRF_OCT_SPI);
+	} else if (dw_spi_ver_is_ge(dws, PSSI, 400A)) {
+		tmpdual = FIELD_PREP(DW_PSSI_CTRLR0_SPI_FRF_MASK,
+				     DW_SPI_CTRLR0_SPI_FRF_DUAL_SPI);
+		tmpquad = FIELD_PREP(DW_PSSI_CTRLR0_SPI_FRF_MASK,
+				     DW_SPI_CTRLR0_SPI_FRF_QUAD_SPI);
+		tmpoct = FIELD_PREP(DW_PSSI_CTRLR0_SPI_FRF_MASK,
+				    DW_SPI_CTRLR0_SPI_FRF_OCT_SPI);
+	} else {
+		return DW_SPI_CTRLR0_SPI_FRF_STD_SPI;
+	}
+
+	tmp_ctrlr0 = dw_readl(dws, DW_SPI_CTRLR0);
+	tmp_spi_ctrlr0 = dw_readl(dws, DW_SPI_SPI_CTRLR0);
+	dw_spi_enable_chip(dws, 0);
+
+	/* test clock stretching */
+	dw_writel(dws, DW_SPI_SPI_CTRLR0, DW_SPI_SPI_CTRLR0_CLK_STRETCH_EN);
+	if ((DW_SPI_SPI_CTRLR0_CLK_STRETCH_EN & dw_readl(dws, DW_SPI_SPI_CTRLR0)) !=
+	    DW_SPI_SPI_CTRLR0_CLK_STRETCH_EN)
+		/*
+		 * If clock stretching is not enabled then do not use
+		 * enhanced mode.
+		 */
+		goto disable_enh;
+
+	/* test dual mode */
+	dw_writel(dws, DW_SPI_CTRLR0, tmpdual);
+	if ((tmpdual & dw_readl(dws, DW_SPI_CTRLR0)) == tmpdual)
+		mode |= SPI_TX_DUAL | SPI_RX_DUAL;
+
+	/* test quad mode */
+	dw_writel(dws, DW_SPI_CTRLR0, tmpquad);
+	if ((tmpquad & dw_readl(dws, DW_SPI_CTRLR0)) == tmpquad)
+		mode |= SPI_TX_QUAD | SPI_RX_QUAD;
+
+	/* test octal mode */
+	dw_writel(dws, DW_SPI_CTRLR0, tmpoct);
+	if ((tmpoct & dw_readl(dws, DW_SPI_CTRLR0)) == tmpoct)
+		mode |= SPI_TX_OCTAL | SPI_RX_OCTAL;
+
+	if (mode)
+		dws->caps |= DW_SPI_CAP_EMODE;
+
+disable_enh:
+	dw_writel(dws, DW_SPI_CTRLR0, tmp_ctrlr0);
+	dw_writel(dws, DW_SPI_SPI_CTRLR0, tmp_spi_ctrlr0);
+	dw_spi_enable_chip(dws, 1);
+
+	return mode;
+}
+
 int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
 {
 	struct spi_controller *master;
@@ -1172,10 +1235,11 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
 		goto err_free_master;
 	}
 
-	dw_spi_init_mem_ops(dws);
-
 	master->use_gpio_descriptors = true;
 	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP;
+	master->mode_bits |= detect_enh_mode(dws);
+	dw_spi_init_mem_ops(dws);
+
 	if (dws->caps & DW_SPI_CAP_DFS32)
 		master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
 	else
-- 
2.30.2