spi: sun4i: Poll for rxfifo to be filled up

To drain rx fifo the fifo need to poll for how much data has
been filled up in rx fifo.

To achieve this, the current code is using wait_for_bit logic
on control register with exchange burst mode mask, which is not
a proper way of waiting for fifo filled up.

So, add code for polling rxfifo to be filled up using fifo
status register.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>

diff --git a/drivers/spi/sun4i_spi.c b/drivers/spi/sun4i_spi.c
index 38cc743..f5f2d56 100644 (file)
--- a/drivers/spi/sun4i_spi.c
+++ b/drivers/spi/sun4i_spi.c
@@ -31,6 +31,8 @@
 
 #include <asm/arch/clock.h>
 
+#include <linux/iopoll.h>
+
 #define SUN4I_FIFO_DEPTH       64
 
 #define SUN4I_RXDATA_REG       0x00
@@ -46,7 +48,6 @@
 #define SUN4I_CTL_LMTF                 BIT(6)
 #define SUN4I_CTL_TF_RST               BIT(8)
 #define SUN4I_CTL_RF_RST               BIT(9)
-#define SUN4I_CTL_XCH_MASK             0x0400
 #define SUN4I_CTL_XCH                  BIT(10)
 #define SUN4I_CTL_CS_MASK              0x3000
 #define SUN4I_CTL_CS(cs)               (((cs) << 12) & SUN4I_CTL_CS_MASK)
@@ -308,7 +309,7 @@ static int sun4i_spi_xfer(struct udevice *dev, unsigned int bitlen,
        struct dm_spi_slave_platdata *slave_plat = dev_get_parent_platdata(dev);
 
        u32 len = bitlen / 8;
-       u32 reg;
+       u32 reg, rx_fifocnt;
        u8 nbytes;
        int ret;
 
@@ -343,10 +344,12 @@ static int sun4i_spi_xfer(struct udevice *dev, unsigned int bitlen,
                reg = readl(&priv->regs->ctl);
                writel(reg | SUN4I_CTL_XCH, &priv->regs->ctl);
 
-               /* Wait transfer to complete */
-               ret = wait_for_bit_le32(&priv->regs->ctl, SUN4I_CTL_XCH_MASK,
-                                       false, SUN4I_SPI_TIMEOUT_US, false);
-               if (ret) {
+               /* Wait till RX FIFO to be empty */
+               ret = readl_poll_timeout(&priv->regs->fifo_sta, rx_fifocnt,
+                                        (((rx_fifocnt & SUN4I_FIFO_STA_RF_CNT_MASK) >>
+                                        SUN4I_FIFO_STA_RF_CNT_BITS) >= nbytes),
+                                        SUN4I_SPI_TIMEOUT_US);
+               if (ret < 0) {
                        printf("ERROR: sun4i_spi: Timeout transferring data\n");
                        sun4i_spi_set_cs(bus, slave_plat->cs, false);
                        return ret;