spi: s3c64xx: group the CS signalling writes in a single function

To enable/disable the CS line, the driver performs a writel in
the S3C64XX_SPI_SLAVE_SEL registers. Group the register's
configuration in a single function.
Signed-off-by: NAndi Shyti <andi.shyti@samsung.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

drivers/spi/spi-s3c64xx.c

@@ -310,6 +310,28 @@ static void prepare_dma(struct s3c64xx_spi_dma_data *dma,
 	dma_async_issue_pending(dma->ch);
 }
 
+static void s3c64xx_spi_set_cs(struct spi_device *spi, bool enable)
+{
+	struct s3c64xx_spi_driver_data *sdd =
+					spi_master_get_devdata(spi->master);
+
+	if (enable) {
+		if (!(sdd->port_conf->quirks & S3C64XX_SPI_QUIRK_CS_AUTO)) {
+			writel(0, sdd->regs + S3C64XX_SPI_SLAVE_SEL);
+		} else {
+			u32 ssel = readl(sdd->regs + S3C64XX_SPI_SLAVE_SEL);
+
+			ssel |= (S3C64XX_SPI_SLAVE_AUTO |
+						S3C64XX_SPI_SLAVE_NSC_CNT_2);
+			writel(ssel, sdd->regs + S3C64XX_SPI_SLAVE_SEL);
+		}
+	} else {
+		if (!(sdd->port_conf->quirks & S3C64XX_SPI_QUIRK_CS_AUTO))
+		writel(S3C64XX_SPI_SLAVE_SIG_INACT,
+		sdd->regs + S3C64XX_SPI_SLAVE_SEL);
+	}
+}
+
 static int s3c64xx_spi_prepare_transfer(struct spi_master *spi)
 {
 	struct s3c64xx_spi_driver_data *sdd = spi_master_get_devdata(spi);
@@ -706,12 +728,7 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master,
 	enable_datapath(sdd, spi, xfer, use_dma);
 
 	/* Start the signals */
-	if (!(sdd->port_conf->quirks & S3C64XX_SPI_QUIRK_CS_AUTO))
-		writel(0, sdd->regs + S3C64XX_SPI_SLAVE_SEL);
-	else
-		writel(readl(sdd->regs + S3C64XX_SPI_SLAVE_SEL)
-			| S3C64XX_SPI_SLAVE_AUTO | S3C64XX_SPI_SLAVE_NSC_CNT_2,
-			sdd->regs + S3C64XX_SPI_SLAVE_SEL);
+	s3c64xx_spi_set_cs(spi, true);
 
 	spin_unlock_irqrestore(&sdd->lock, flags);
 
@@ -861,16 +878,15 @@ static int s3c64xx_spi_setup(struct spi_device *spi)
 
 	pm_runtime_mark_last_busy(&sdd->pdev->dev);
 	pm_runtime_put_autosuspend(&sdd->pdev->dev);
-	if (!(sdd->port_conf->quirks & S3C64XX_SPI_QUIRK_CS_AUTO))
-		writel(S3C64XX_SPI_SLAVE_SIG_INACT, sdd->regs + S3C64XX_SPI_SLAVE_SEL);
+	s3c64xx_spi_set_cs(spi, false);
+
 	return 0;
 
 setup_exit:
 	pm_runtime_mark_last_busy(&sdd->pdev->dev);
 	pm_runtime_put_autosuspend(&sdd->pdev->dev);
 	/* setup() returns with device de-selected */
-	if (!(sdd->port_conf->quirks & S3C64XX_SPI_QUIRK_CS_AUTO))
-		writel(S3C64XX_SPI_SLAVE_SIG_INACT, sdd->regs + S3C64XX_SPI_SLAVE_SEL);
+	s3c64xx_spi_set_cs(spi, false);
 
 	if (gpio_is_valid(spi->cs_gpio))
 		gpio_free(spi->cs_gpio);