spi: s3c64xx: prepare for a different flavor of iowrite rep

There are SoCs (gs101) that allow only 32 bit register accesses. As the
requirement is rare enough, for those SoCs we'll open code in the driver
some s3c64xx_iowrite{8,16}_32_rep() accessors. Prepare for such addition.

Suggested-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20240207111516.2563218-3-tudor.ambarus@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-s3c64xx.c

@@ -414,6 +414,26 @@ static bool s3c64xx_spi_can_dma(struct spi_controller *host,
 
 }
 
+static void s3c64xx_iowrite_rep(const struct s3c64xx_spi_driver_data *sdd,
+				struct spi_transfer *xfer)
+{
+	void __iomem *addr = sdd->regs + S3C64XX_SPI_TX_DATA;
+	const void *buf = xfer->tx_buf;
+	unsigned int len = xfer->len;
+
+	switch (sdd->cur_bpw) {
+	case 32:
+		iowrite32_rep(addr, buf, len / 4);
+		break;
+	case 16:
+		iowrite16_rep(addr, buf, len / 2);
+		break;
+	default:
+		iowrite8_rep(addr, buf, len);
+		break;
+	}
+}
+
 static int s3c64xx_enable_datapath(struct s3c64xx_spi_driver_data *sdd,
 				    struct spi_transfer *xfer, int dma_mode)
 {
@@ -447,20 +467,7 @@ static int s3c64xx_enable_datapath(struct s3c64xx_spi_driver_data *sdd,
 			modecfg |= S3C64XX_SPI_MODE_TXDMA_ON;
 			ret = prepare_dma(&sdd->tx_dma, &xfer->tx_sg);
 		} else {
-			switch (sdd->cur_bpw) {
-			case 32:
-				iowrite32_rep(regs + S3C64XX_SPI_TX_DATA,
-					xfer->tx_buf, xfer->len / 4);
-				break;
-			case 16:
-				iowrite16_rep(regs + S3C64XX_SPI_TX_DATA,
-					xfer->tx_buf, xfer->len / 2);
-				break;
-			default:
-				iowrite8_rep(regs + S3C64XX_SPI_TX_DATA,
-					xfer->tx_buf, xfer->len);
-				break;
-			}
+			s3c64xx_iowrite_rep(sdd, xfer);
 		}
 	}