[PATCH 4/7] spi: realtek-rtl: add parallel IO suppport

[Birger Koblitz <mail@xxxxxxxxxxxxxxxxx>]

The Realtek SoCs are capable of dual and/or quad IO.
Add a function to enable this functionality.

Signed-off-by: Birger Koblitz <mail@xxxxxxxxxxxxxxxxx>
---
 drivers/spi/spi-realtek-rtl.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/spi/spi-realtek-rtl.c b/drivers/spi/spi-realtek-rtl.c
index 5979233522f4..25a90493bf6e 100644
--- a/drivers/spi/spi-realtek-rtl.c
+++ b/drivers/spi/spi-realtek-rtl.c
@@ -25,6 +25,9 @@ struct rtspi {
 #define RTL_SPI_SFCSR_CSB3		BIT(14)
 #define RTL_SPI_SFCSR_RDY		BIT(27)
 #define RTL_SPI_SFCSR_CS		BIT(24)
+#define RTL_SPI_SFCSR_WIDTH_MASK	~(0x03 << 25)
+#define RTL_SPI_SFCSR_WIDTH_DUAL	(0x01 << 25)
+#define RTL_SPI_SFCSR_WIDTH_QUAD	(0x02 << 25)
 #define RTL_SPI_SFCSR_LEN_MASK		~(0x03 << 28)
 #define RTL_SPI_SFCSR_LEN1		(0x00 << 28)
 #define RTL_SPI_SFCSR_LEN4		(0x03 << 28)
@@ -118,6 +121,25 @@ static void rcv1(struct rtspi *rtspi, u8 *buf)
 	*buf = readl(REG(RTL_SPI_SFDR)) >> 24;
 }

+static void set_mode(struct rtspi *rtspi, unsigned int mode)
+{
+	u32 value;
+
+	value = readl(REG(RTL_SPI_SFCSR));
+	value &= RTL_SPI_SFCSR_WIDTH_MASK;
+	switch (mode) {
+	case SPI_NBITS_QUAD:
+		value |= RTL_SPI_SFCSR_WIDTH_QUAD;
+		break;
+	case SPI_NBITS_DUAL:
+		value |= RTL_SPI_SFCSR_WIDTH_DUAL;
+		break;
+	default:
+		break;
+	}
+	writel(value, REG(RTL_SPI_SFCSR));
+}
+
 static int transfer_one(struct spi_controller *ctrl, struct spi_device *spi,
 			struct spi_transfer *xfer)
 {
--
2.25.1