[PATCH v1] spi: imx: mx51-ecspi: fix clk polarity and phase configuration for CS > 4

[Oleksij Rempel <o.rempel@pengutronix.de>]

Fix support for boards with more then 4 chip select lines. Other wise if
CS > 4 is used, we will write trash to the clk configuration register.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 drivers/spi/spi-imx.c | 37 +++++++++++++++++++++++++------------
 1 file changed, 25 insertions(+), 12 deletions(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index b2dd0a4d2446..2d29b893e9e0 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -265,6 +265,7 @@ static bool spi_imx_can_dma(struct spi_master *master, struct spi_device *spi,
 #define MX51_ECSPI_CONFIG_SBBCTRL(cs)	(1 << ((cs) +  8))
 #define MX51_ECSPI_CONFIG_SSBPOL(cs)	(1 << ((cs) + 12))
 #define MX51_ECSPI_CONFIG_SCLKCTL(cs)	(1 << ((cs) + 20))
+#define MX51_ECSPI_MAX_HW_CS		4
 
 #define MX51_ECSPI_INT		0x10
 #define MX51_ECSPI_INT_TEEN		(1 <<  0)
@@ -515,6 +516,7 @@ static int mx51_ecspi_prepare_message(struct spi_imx_data *spi_imx,
 	u32 min_speed_hz = ~0U;
 	u32 testreg, delay;
 	u32 cfg = readl(spi_imx->base + MX51_ECSPI_CONFIG);
+	int chip_select;
 
 	/* set Master or Slave mode */
 	if (spi_imx->slave_mode)
@@ -528,8 +530,19 @@ static int mx51_ecspi_prepare_message(struct spi_imx_data *spi_imx,
 	if (spi->mode & SPI_READY)
 		ctrl |= MX51_ECSPI_CTRL_DRCTL(spi_imx->spi_drctl);
 
-	/* set chip select to use */
-	ctrl |= MX51_ECSPI_CTRL_CS(spi->chip_select);
+	if (spi->cs_gpiod) {
+		chip_select = 0;
+	} else {
+		if (spi->chip_select >= MX51_ECSPI_MAX_HW_CS) {
+			dev_err(spi_imx->dev, "Native chip_select is out of supported range: %i\n",
+				spi->chip_select);
+			return -EINVAL;
+		}
+
+		/* set HW chip select to use */
+		ctrl |= MX51_ECSPI_CTRL_CS(spi->chip_select);
+		chip_select = spi->chip_select;
+	}
 
 	/*
 	 * The ctrl register must be written first, with the EN bit set other
@@ -550,27 +563,27 @@ static int mx51_ecspi_prepare_message(struct spi_imx_data *spi_imx,
 	 * BURST_LENGTH + 1 bits are received
 	 */
 	if (spi_imx->slave_mode && is_imx53_ecspi(spi_imx))
-		cfg &= ~MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
+		cfg &= ~MX51_ECSPI_CONFIG_SBBCTRL(chip_select);
 	else
-		cfg |= MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
+		cfg |= MX51_ECSPI_CONFIG_SBBCTRL(chip_select);
 
 	if (spi->mode & SPI_CPHA)
-		cfg |= MX51_ECSPI_CONFIG_SCLKPHA(spi->chip_select);
+		cfg |= MX51_ECSPI_CONFIG_SCLKPHA(chip_select);
 	else
-		cfg &= ~MX51_ECSPI_CONFIG_SCLKPHA(spi->chip_select);
+		cfg &= ~MX51_ECSPI_CONFIG_SCLKPHA(chip_select);
 
 	if (spi->mode & SPI_CPOL) {
-		cfg |= MX51_ECSPI_CONFIG_SCLKPOL(spi->chip_select);
-		cfg |= MX51_ECSPI_CONFIG_SCLKCTL(spi->chip_select);
+		cfg |= MX51_ECSPI_CONFIG_SCLKPOL(chip_select);
+		cfg |= MX51_ECSPI_CONFIG_SCLKCTL(chip_select);
 	} else {
-		cfg &= ~MX51_ECSPI_CONFIG_SCLKPOL(spi->chip_select);
-		cfg &= ~MX51_ECSPI_CONFIG_SCLKCTL(spi->chip_select);
+		cfg &= ~MX51_ECSPI_CONFIG_SCLKPOL(chip_select);
+		cfg &= ~MX51_ECSPI_CONFIG_SCLKCTL(chip_select);
 	}
 
 	if (spi->mode & SPI_CS_HIGH)
-		cfg |= MX51_ECSPI_CONFIG_SSBPOL(spi->chip_select);
+		cfg |= MX51_ECSPI_CONFIG_SSBPOL(chip_select);
 	else
-		cfg &= ~MX51_ECSPI_CONFIG_SSBPOL(spi->chip_select);
+		cfg &= ~MX51_ECSPI_CONFIG_SSBPOL(chip_select);
 
 	writel(cfg, spi_imx->base + MX51_ECSPI_CONFIG);
 
-- 
2.30.2