[U-Boot] [PATCH v3 1/9] spi: sun4i: Poll for rxfifo to be filled up

Jagan Teki
2019-02-27T14:32:05Z

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>
---
drivers/spi/sun4i_spi.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/spi/sun4i_spi.c b/drivers/spi/sun4i_spi.c
index 38cc743c61..f5f2d5635a 100644
--- 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;
--
2.18.0.321.gffc6fa0e3