[PATCH v1 1/3] spi: sun6i: add quirk for dual and quad SPI modes support

[Maksim Kiselev <bigunclemax@gmail.com>]

New Allwinner's SPI controllers can support dual and quad SPI modes.
To enable one of these modes, we should set the corresponding bit in
the SUN6I_BURST_CTL_CNT_REG register. DRM (28 bits) for dual mode and
Quad_EN (29 bits) for quad transmission.

Signed-off-by: Maksim Kiselev <bigunclemax@gmail.com>
---
 drivers/spi/spi-sun6i.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-sun6i.c b/drivers/spi/spi-sun6i.c
index 30d541612253..cec2747235ab 100644
--- a/drivers/spi/spi-sun6i.c
+++ b/drivers/spi/spi-sun6i.c
@@ -83,6 +83,9 @@
 #define SUN6I_XMIT_CNT_REG		0x34
 
 #define SUN6I_BURST_CTL_CNT_REG		0x38
+#define SUN6I_BURST_CTL_CNT_STC_MASK		GENMASK(23, 0)
+#define SUN6I_BURST_CTL_CNT_DRM			BIT(28)
+#define SUN6I_BURST_CTL_CNT_QUAD_EN		BIT(29)
 
 #define SUN6I_TXDATA_REG		0x200
 #define SUN6I_RXDATA_REG		0x300
@@ -90,6 +93,7 @@
 struct sun6i_spi_cfg {
 	unsigned long		fifo_depth;
 	bool			has_clk_ctl;
+	u32			mode_bits;
 };
 
 struct sun6i_spi {
@@ -266,7 +270,7 @@ static int sun6i_spi_transfer_one(struct spi_master *master,
 	unsigned int div, div_cdr1, div_cdr2, timeout;
 	unsigned int start, end, tx_time;
 	unsigned int trig_level;
-	unsigned int tx_len = 0, rx_len = 0;
+	unsigned int tx_len = 0, rx_len = 0, nbits = 0;
 	bool use_dma;
 	int ret = 0;
 	u32 reg;
@@ -418,13 +422,29 @@ static int sun6i_spi_transfer_one(struct spi_master *master,
 	sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG, reg);
 
 	/* Setup the transfer now... */
-	if (sspi->tx_buf)
+	if (sspi->tx_buf) {
 		tx_len = tfr->len;
+		nbits = tfr->tx_nbits;
+	} else if (tfr->rx_buf) {
+		nbits = tfr->rx_nbits;
+	}
+
+	switch (nbits) {
+	case SPI_NBITS_DUAL:
+		reg = SUN6I_BURST_CTL_CNT_DRM;
+		break;
+	case SPI_NBITS_QUAD:
+		reg = SUN6I_BURST_CTL_CNT_QUAD_EN;
+		break;
+	case SPI_NBITS_SINGLE:
+	default:
+		reg = FIELD_PREP(SUN6I_BURST_CTL_CNT_STC_MASK, tx_len);
+	}
 
 	/* Setup the counters */
+	sun6i_spi_write(sspi, SUN6I_BURST_CTL_CNT_REG, reg);
 	sun6i_spi_write(sspi, SUN6I_BURST_CNT_REG, tfr->len);
 	sun6i_spi_write(sspi, SUN6I_XMIT_CNT_REG, tx_len);
-	sun6i_spi_write(sspi, SUN6I_BURST_CTL_CNT_REG, tx_len);
 
 	if (!use_dma) {
 		/* Fill the TX FIFO */
@@ -623,7 +643,8 @@ static int sun6i_spi_probe(struct platform_device *pdev)
 	master->set_cs = sun6i_spi_set_cs;
 	master->transfer_one = sun6i_spi_transfer_one;
 	master->num_chipselect = 4;
-	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST;
+	master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_LSB_FIRST |
+			    sspi->cfg->mode_bits;
 	master->bits_per_word_mask = SPI_BPW_MASK(8);
 	master->dev.of_node = pdev->dev.of_node;
 	master->auto_runtime_pm = true;
-- 
2.39.2