spi: s3c64xx: add support for google,gs101-spi

Merge series from Tudor Ambarus <tudor.ambarus@linaro.org>:

The Google GCS101 uses a variant of the Samsung SPI controller IP.

Documentation/devicetree/bindings/spi/samsung,spi.yaml

@@ -17,6 +17,7 @@ properties:
   compatible:
     oneOf:
       - enum:
+          - google,gs101-spi
           - samsung,s3c2443-spi # for S3C2443, S3C2416 and S3C2450
           - samsung,s3c6410-spi
           - samsung,s5pv210-spi # for S5PV210 and S5PC110

drivers/spi/spi-s3c64xx.c

@@ -17,7 +17,7 @@
 
 #include <linux/platform_data/spi-s3c64xx.h>
 
-#define MAX_SPI_PORTS		12
+#define MAX_SPI_PORTS		16
 #define S3C64XX_SPI_QUIRK_CS_AUTO	(1 << 1)
 #define AUTOSUSPEND_TIMEOUT	2000
 
@@ -142,6 +142,7 @@ struct s3c64xx_spi_dma_data {
  *	prescaler unit.
  * @clk_ioclk: True if clock is present on this device
  * @has_loopback: True if loopback mode can be supported
+ * @use_32bit_io: True if the SoC allows only 32-bit register accesses.
  *
  * The Samsung s3c64xx SPI controller are used on various Samsung SoC's but
  * differ in some aspects such as the size of the fifo and spi bus clock
@@ -158,6 +159,7 @@ struct s3c64xx_spi_port_config {
 	bool	clk_from_cmu;
 	bool	clk_ioclk;
 	bool	has_loopback;
+	bool	use_32bit_io;
 };
 
 /**
@@ -414,6 +416,56 @@ static bool s3c64xx_spi_can_dma(struct spi_controller *host,
 
 }
 
+static void s3c64xx_iowrite8_32_rep(volatile void __iomem *addr,
+				    const void *buffer, unsigned int count)
+{
+	if (count) {
+		const u8 *buf = buffer;
+
+		do {
+			__raw_writel(*buf++, addr);
+		} while (--count);
+	}
+}
+
+static void s3c64xx_iowrite16_32_rep(volatile void __iomem *addr,
+				     const void *buffer, unsigned int count)
+{
+	if (count) {
+		const u16 *buf = buffer;
+
+		do {
+			__raw_writel(*buf++, addr);
+		} while (--count);
+	}
+}
+
+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:
+		if (sdd->port_conf->use_32bit_io)
+			s3c64xx_iowrite16_32_rep(addr, buf, len / 2);
+		else
+			iowrite16_rep(addr, buf, len / 2);
+		break;
+	default:
+		if (sdd->port_conf->use_32bit_io)
+			s3c64xx_iowrite8_32_rep(addr, buf, len);
+		else
+			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 +499,7 @@ 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);
 		}
 	}
 
@@ -1495,6 +1534,19 @@ static const struct s3c64xx_spi_port_config fsd_spi_port_config = {
 	.quirks		= S3C64XX_SPI_QUIRK_CS_AUTO,
 };
 
+static const struct s3c64xx_spi_port_config gs101_spi_port_config = {
+	.fifo_lvl_mask	= { 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f,
+			    0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7f},
+	.rx_lvl_offset	= 15,
+	.tx_st_done	= 25,
+	.clk_div	= 4,
+	.high_speed	= true,
+	.clk_from_cmu	= true,
+	.has_loopback	= true,
+	.use_32bit_io	= true,
+	.quirks		= S3C64XX_SPI_QUIRK_CS_AUTO,
+};
+
 static const struct platform_device_id s3c64xx_spi_driver_ids[] = {
 	{
 		.name		= "s3c2443-spi",
@@ -1507,6 +1559,9 @@ static const struct platform_device_id s3c64xx_spi_driver_ids[] = {
 };
 
 static const struct of_device_id s3c64xx_spi_dt_match[] = {
+	{ .compatible = "google,gs101-spi",
+			.data = &gs101_spi_port_config,
+	},
 	{ .compatible = "samsung,s3c2443-spi",
 			.data = (void *)&s3c2443_spi_port_config,
 	},