spi: spi-sun6i: sun6i_spi_drain_fifo(): introduce sun6i_spi_get_rx_fifo_count() and make use of it

This patch introduces the function sun6i_spi_get_rx_fifo_count(), similar to
the existing sun6i_spi_get_tx_fifo_count(), to make the sun6i_spi_drain_fifo()
function a bit easier to read.
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20200706143443.9855-7-mkl@pengutronix.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-sun6i.c

@@ -59,8 +59,7 @@
 #define SUN6I_FIFO_CTL_TF_RST			BIT(31)
 
 #define SUN6I_FIFO_STA_REG		0x1c
-#define SUN6I_FIFO_STA_RF_CNT_MASK		0x7f
-#define SUN6I_FIFO_STA_RF_CNT_BITS		0
+#define SUN6I_FIFO_STA_RF_CNT_MASK		GENMASK(7, 0)
 #define SUN6I_FIFO_STA_TF_CNT_MASK		GENMASK(23, 16)
 
 #define SUN6I_CLK_CTL_REG		0x24
@@ -106,6 +105,13 @@ static inline void sun6i_spi_write(struct sun6i_spi *sspi, u32 reg, u32 value)
 	writel(value, sspi->base_addr + reg);
 }
 
+static inline u32 sun6i_spi_get_rx_fifo_count(struct sun6i_spi *sspi)
+{
+	u32 reg = sun6i_spi_read(sspi, SUN6I_FIFO_STA_REG);
+
+	return FIELD_GET(SUN6I_FIFO_STA_RF_CNT_MASK, reg);
+}
+
 static inline u32 sun6i_spi_get_tx_fifo_count(struct sun6i_spi *sspi)
 {
 	u32 reg = sun6i_spi_read(sspi, SUN6I_FIFO_STA_REG);
@@ -131,13 +137,11 @@ static inline void sun6i_spi_disable_interrupt(struct sun6i_spi *sspi, u32 mask)
 
 static inline void sun6i_spi_drain_fifo(struct sun6i_spi *sspi, int len)
 {
-	u32 reg, cnt;
+	u32 cnt;
 	u8 byte;
 
 	/* See how much data is available */
-	reg = sun6i_spi_read(sspi, SUN6I_FIFO_STA_REG);
-	reg &= SUN6I_FIFO_STA_RF_CNT_MASK;
-	cnt = reg >> SUN6I_FIFO_STA_RF_CNT_BITS;
+	cnt = sun6i_spi_get_rx_fifo_count(sspi);
 
 	if (len > cnt)
 		len = cnt;