spi: imx: mx51-ecspi: Move some initialisation to prepare_message hook.

The relevant difference between prepare_message and config is that the
former is run before the CS signal is asserted. So the polarity of the
CLK line must be configured in prepare_message as an edge generated by
config might already result in a latch of the MOSI line.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
[ukleinek: backport to v4.14.x]
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 3fdb065..df18d07 100644 (file)
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -443,14 +443,9 @@ static void mx51_ecspi_trigger(struct spi_imx_data *spi_imx)
 static int mx51_ecspi_prepare_message(struct spi_imx_data *spi_imx,
                                      struct spi_message *msg)
 {
-       return 0;
-}
-
-static int mx51_ecspi_config(struct spi_device *spi)
-{
-       struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
+       struct spi_device *spi = msg->spi;
        u32 ctrl = MX51_ECSPI_CTRL_ENABLE;
-       u32 clk = spi_imx->speed_hz, delay, reg;
+       u32 testreg;
        u32 cfg = readl(spi_imx->base + MX51_ECSPI_CONFIG);
 
        /*
@@ -468,14 +463,21 @@ static int mx51_ecspi_config(struct spi_device *spi)
        if (spi->mode & SPI_READY)
                ctrl |= MX51_ECSPI_CTRL_DRCTL(spi_imx->spi_drctl);
 
-       /* set clock speed */
-       ctrl |= mx51_ecspi_clkdiv(spi_imx, spi_imx->speed_hz, &clk);
-       spi_imx->spi_bus_clk = clk;
-
        /* set chip select to use */
        ctrl |= MX51_ECSPI_CTRL_CS(spi->chip_select);
 
-       ctrl |= (spi_imx->bits_per_word - 1) << MX51_ECSPI_CTRL_BL_OFFSET;
+       /*
+        * The ctrl register must be written first, with the EN bit set other
+        * registers must not be written to.
+        */
+       writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
+
+       testreg = readl(spi_imx->base + MX51_ECSPI_TESTREG);
+       if (spi->mode & SPI_LOOP)
+               testreg |= MX51_ECSPI_TESTREG_LBC;
+       else
+               testreg &= ~MX51_ECSPI_TESTREG_LBC;
+       writel(testreg, spi_imx->base + MX51_ECSPI_TESTREG);
 
        cfg |= MX51_ECSPI_CONFIG_SBBCTRL(spi->chip_select);
 
@@ -491,26 +493,38 @@ static int mx51_ecspi_config(struct spi_device *spi)
                cfg &= ~MX51_ECSPI_CONFIG_SCLKPOL(spi->chip_select);
                cfg &= ~MX51_ECSPI_CONFIG_SCLKCTL(spi->chip_select);
        }
+
        if (spi->mode & SPI_CS_HIGH)
                cfg |= MX51_ECSPI_CONFIG_SSBPOL(spi->chip_select);
        else
                cfg &= ~MX51_ECSPI_CONFIG_SSBPOL(spi->chip_select);
 
+       writel(cfg, spi_imx->base + MX51_ECSPI_CONFIG);
+
+       return 0;
+}
+
+static int mx51_ecspi_config(struct spi_device *spi)
+{
+       struct spi_imx_data *spi_imx = spi_master_get_devdata(spi->master);
+       u32 ctrl = readl(spi_imx->base + MX51_ECSPI_CTRL);
+       u32 clk = spi_imx->speed_hz, delay;
+
+       /* Clear BL field and set the right value */
+       ctrl &= ~MX51_ECSPI_CTRL_BL_MASK;
+       ctrl |= (spi_imx->bits_per_word - 1) << MX51_ECSPI_CTRL_BL_OFFSET;
+
+       /* set clock speed */
+       ctrl &= ~(0xf << MX51_ECSPI_CTRL_POSTDIV_OFFSET |
+                 0xf << MX51_ECSPI_CTRL_PREDIV_OFFSET);
+       ctrl |= mx51_ecspi_clkdiv(spi_imx, spi_imx->speed_hz, &clk);
+       spi_imx->spi_bus_clk = clk;
+
        if (spi_imx->usedma)
                ctrl |= MX51_ECSPI_CTRL_SMC;
 
-       /* CTRL register always go first to bring out controller from reset */
        writel(ctrl, spi_imx->base + MX51_ECSPI_CTRL);
 
-       reg = readl(spi_imx->base + MX51_ECSPI_TESTREG);
-       if (spi->mode & SPI_LOOP)
-               reg |= MX51_ECSPI_TESTREG_LBC;
-       else
-               reg &= ~MX51_ECSPI_TESTREG_LBC;
-       writel(reg, spi_imx->base + MX51_ECSPI_TESTREG);
-
-       writel(cfg, spi_imx->base + MX51_ECSPI_CONFIG);
-
        /*
         * Wait until the changes in the configuration register CONFIGREG
         * propagate into the hardware. It takes exactly one tick of the
@@ -532,7 +546,6 @@ static int mx51_ecspi_config(struct spi_device *spi)
         * Configure the DMA register: setup the watermark
         * and enable DMA request.
         */
-
        writel(MX51_ECSPI_DMA_RX_WML(spi_imx->wml) |
                MX51_ECSPI_DMA_TX_WML(spi_imx->wml) |
                MX51_ECSPI_DMA_RXT_WML(spi_imx->wml) |