[PATCH 10/14] spi: spi-fsl-dspi: Enable modified transfer protocol

[James Clark <james.clark@linaro.org>]

From: Andra-Teodora Ilie <andra.ilie@nxp.com>

Set MTFE bit in MCR register for frequencies higher than 25MHz.

Signed-off-by: Andra-Teodora Ilie <andra.ilie@nxp.com>
Signed-off-by: Bogdan-Gabriel Roman <bogdan-gabriel.roman@nxp.com>
Signed-off-by: Larisa Grigore <larisa.grigore@nxp.com>
Signed-off-by: James Clark <james.clark@linaro.org>
---
 drivers/spi/spi-fsl-dspi.c | 44 +++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 41 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index 0613642d769d..31521dac1580 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -24,6 +24,7 @@
 
 #define SPI_MCR				0x00
 #define SPI_MCR_HOST			BIT(31)
+#define SPI_MCR_MTFE			BIT(26)
 #define SPI_MCR_PCSIS(x)		((x) << 16)
 #define SPI_MCR_CLR_TXF			BIT(11)
 #define SPI_MCR_CLR_RXF			BIT(10)
@@ -37,6 +38,7 @@
 
 #define SPI_CTAR(x)			(0x0c + (((x) & GENMASK(2, 0)) * 4))
 #define SPI_CTAR_FMSZ(x)		(((x) << 27) & GENMASK(30, 27))
+#define SPI_CTAR_DBR			BIT(31)
 #define SPI_CTAR_CPOL			BIT(26)
 #define SPI_CTAR_CPHA			BIT(25)
 #define SPI_CTAR_LSBFE			BIT(24)
@@ -110,6 +112,8 @@
 
 #define DMA_COMPLETION_TIMEOUT		msecs_to_jiffies(3000)
 
+#define SPI_25MHZ			25000000
+
 struct chip_data {
 	u32			ctar_val;
 };
@@ -345,6 +349,7 @@ struct fsl_dspi {
 	const void				*tx;
 	void					*rx;
 	u16					tx_cmd;
+	bool					mtf_enabled;
 	const struct fsl_dspi_devtype_data	*devtype_data;
 
 	struct completion			xfer_done;
@@ -721,7 +726,7 @@ static void dspi_release_dma(struct fsl_dspi *dspi)
 }
 
 static void hz_to_spi_baud(char *pbr, char *br, int speed_hz,
-			   unsigned long clkrate)
+			   unsigned long clkrate, bool mtf_enabled)
 {
 	/* Valid baud rate pre-scaler values */
 	int pbr_tbl[4] = {2, 3, 5, 7};
@@ -738,7 +743,13 @@ static void hz_to_spi_baud(char *pbr, char *br, int speed_hz,
 
 	for (i = 0; i < ARRAY_SIZE(brs); i++)
 		for (j = 0; j < ARRAY_SIZE(pbr_tbl); j++) {
-			scale = brs[i] * pbr_tbl[j];
+			if (mtf_enabled) {
+				/* In MTF mode DBR=1 so frequency is doubled */
+				scale = (brs[i] * pbr_tbl[j]) / 2;
+			} else {
+				scale = brs[i] * pbr_tbl[j];
+			}
+
 			if (scale >= scale_needed) {
 				if (scale < minscale) {
 					minscale = scale;
@@ -1120,6 +1131,20 @@ static int dspi_transfer_one_message(struct spi_controller *ctlr,
 	return status;
 }
 
+static int dspi_set_mtf(struct fsl_dspi *dspi)
+{
+	if (spi_controller_is_target(dspi->ctlr))
+		return 0;
+
+	if (dspi->mtf_enabled)
+		regmap_update_bits(dspi->regmap, SPI_MCR, SPI_MCR_MTFE,
+				   SPI_MCR_MTFE);
+	else
+		regmap_update_bits(dspi->regmap, SPI_MCR, SPI_MCR_MTFE, 0);
+
+	return 0;
+}
+
 static int dspi_setup(struct spi_device *spi)
 {
 	struct fsl_dspi *dspi = spi_controller_get_devdata(spi->controller);
@@ -1178,7 +1203,15 @@ static int dspi_setup(struct spi_device *spi)
 		cs_sck_delay, sck_cs_delay);
 
 	clkrate = clk_get_rate(dspi->clk);
-	hz_to_spi_baud(&pbr, &br, spi->max_speed_hz, clkrate);
+
+	if (is_s32g_dspi(dspi) && spi->max_speed_hz > SPI_25MHZ)
+		dspi->mtf_enabled = true;
+	else
+		dspi->mtf_enabled = false;
+
+	dspi_set_mtf(dspi);
+
+	hz_to_spi_baud(&pbr, &br, spi->max_speed_hz, clkrate, dspi->mtf_enabled);
 
 	/* Set PCS to SCK delay scale values */
 	ns_delay_scale(&pcssck, &cssck, cs_sck_delay, clkrate);
@@ -1200,6 +1233,9 @@ static int dspi_setup(struct spi_device *spi)
 				  SPI_CTAR_PBR(pbr) |
 				  SPI_CTAR_BR(br);
 
+		if (dspi->mtf_enabled)
+			chip->ctar_val |= SPI_CTAR_DBR;
+
 		if (spi->mode & SPI_LSB_FIRST)
 			chip->ctar_val |= SPI_CTAR_LSBFE;
 	}
@@ -1324,6 +1360,8 @@ static int dspi_resume(struct device *dev)
 		return ret;
 	}
 
+	dspi_set_mtf(dspi);
+
 	if (dspi->irq)
 		enable_irq(dspi->irq);
 

-- 
2.34.1