spi: dw: Detach SPI device specific CR0 config method

Indeed there is no point in detecting the SPI peripheral device parameters
and initializing the CR0 register fields each time an SPI transfer is
executed. Instead let's define a dedicated CR0 chip-data member, which
will be initialized in accordance with the SPI device settings at the
moment of setting it up.

By doing so we'll finally make the SPI device chip_data serving as it's
supposed to - to preserve the SPI device specific DW SPI configuration.
See spi-fsl-dspi.c, spi-pl022.c, spi-pxa2xx.c drivers for example of the
way the chip data is utilized.
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20201007235511.4935-4-Sergey.Semin@baikalelectronics.ruSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-dw-core.c

@@ -27,6 +27,7 @@ struct chip_data {
 	u16 clk_div;		/* baud rate divider */
 	u32 speed_hz;		/* baud rate */
 
+	u32 cr0;
 	u32 rx_sample_dly;	/* RX sample delay */
 };
 
@@ -228,14 +229,9 @@ static irqreturn_t dw_spi_irq(int irq, void *dev_id)
 	return dws->transfer_handler(dws);
 }
 
-static void dw_spi_update_cr0(struct dw_spi *dws, struct spi_device *spi,
-			      struct spi_transfer *transfer)
+static u32 dw_spi_prepare_cr0(struct dw_spi *dws, struct spi_device *spi)
 {
-	struct chip_data *chip = spi_get_ctldata(spi);
-	u32 cr0;
-
-	/* CTRLR0[ 4/3: 0] Data Frame Size */
-	cr0 = (transfer->bits_per_word - 1);
+	u32 cr0 = 0;
 
 	if (!(dws->caps & DW_SPI_CAP_DWC_SSI)) {
 		/* CTRLR0[ 5: 4] Frame Format */
@@ -251,9 +247,6 @@ static void dw_spi_update_cr0(struct dw_spi *dws, struct spi_device *spi,
 
 		/* CTRLR0[11] Shift Register Loop */
 		cr0 |= ((spi->mode & SPI_LOOP) ? 1 : 0) << SPI_SRL_OFFSET;
-
-		/* CTRLR0[ 9:8] Transfer Mode */
-		cr0 |= chip->tmode << SPI_TMOD_OFFSET;
 	} else {
 		/* CTRLR0[ 7: 6] Frame Format */
 		cr0 |= SSI_MOTO_SPI << DWC_SSI_CTRLR0_FRF_OFFSET;
@@ -269,13 +262,29 @@ static void dw_spi_update_cr0(struct dw_spi *dws, struct spi_device *spi,
 		/* CTRLR0[13] Shift Register Loop */
 		cr0 |= ((spi->mode & SPI_LOOP) ? 1 : 0) << DWC_SSI_CTRLR0_SRL_OFFSET;
 
-		/* CTRLR0[11:10] Transfer Mode */
-		cr0 |= chip->tmode << DWC_SSI_CTRLR0_TMOD_OFFSET;
-
 		if (dws->caps & DW_SPI_CAP_KEEMBAY_MST)
 			cr0 |= DWC_SSI_CTRLR0_KEEMBAY_MST;
 	}
 
+	return cr0;
+}
+
+static void dw_spi_update_cr0(struct dw_spi *dws, struct spi_device *spi,
+			      struct spi_transfer *transfer)
+{
+	struct chip_data *chip = spi_get_ctldata(spi);
+	u32 cr0 = chip->cr0;
+
+	/* CTRLR0[ 4/3: 0] Data Frame Size */
+	cr0 |= (transfer->bits_per_word - 1);
+
+	if (!(dws->caps & DW_SPI_CAP_DWC_SSI))
+		/* CTRLR0[ 9:8] Transfer Mode */
+		cr0 |= chip->tmode << SPI_TMOD_OFFSET;
+	else
+		/* CTRLR0[11:10] Transfer Mode */
+		cr0 |= chip->tmode << DWC_SSI_CTRLR0_TMOD_OFFSET;
+
 	dw_writel(dws, DW_SPI_CTRLR0, cr0);
 }
 
@@ -373,6 +382,7 @@ static void dw_spi_handle_err(struct spi_controller *master,
 /* This may be called twice for each spi dev */
 static int dw_spi_setup(struct spi_device *spi)
 {
+	struct dw_spi *dws = spi_controller_get_devdata(spi->controller);
 	struct chip_data *chip;
 
 	/* Only alloc on first setup */
@@ -396,6 +406,13 @@ static int dw_spi_setup(struct spi_device *spi)
 							dws->max_freq);
 	}
 
+	/*
+	 * Update CR0 data each time the setup callback is invoked since
+	 * the device parameters could have been changed, for instance, by
+	 * the MMC SPI driver or something else.
+	 */
+	chip->cr0 = dw_spi_prepare_cr0(dws, spi);
+
 	chip->tmode = SPI_TMOD_TR;
 
 	return 0;