[PATCH] spi: mediatek: fix fifo rx mode

From: Frank Wunderlich
Date: Tue Jul 06 2021 - 08:41:53 EST


From: Peter Hess <peter.hess@xxxxxxxxxx>

In FIFO mode were two problems:
- RX mode was never handled and
- in this case the tx_buf pointer was NULL and caused an exception

fix this by handling RX mode in mtk_spi_fifo_transfer

Fixes: a568231f4632 ("spi: mediatek: Add spi bus for Mediatek MT8173")
Signed-off-by: Peter Hess <peter.hess@xxxxxxxxxx>
Signed-off-by: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx>
---
drivers/spi/spi-mt65xx.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 976f73b9e299..8d5fa7f1e506 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -427,13 +427,23 @@ static int mtk_spi_fifo_transfer(struct spi_master *master,
mtk_spi_setup_packet(master);

cnt = xfer->len / 4;
- iowrite32_rep(mdata->base + SPI_TX_DATA_REG, xfer->tx_buf, cnt);
+ if (xfer->tx_buf)
+ iowrite32_rep(mdata->base + SPI_TX_DATA_REG, xfer->tx_buf, cnt);
+
+ if (xfer->rx_buf)
+ ioread32_rep(mdata->base + SPI_RX_DATA_REG, xfer->rx_buf, cnt);

remainder = xfer->len % 4;
if (remainder > 0) {
reg_val = 0;
- memcpy(&reg_val, xfer->tx_buf + (cnt * 4), remainder);
- writel(reg_val, mdata->base + SPI_TX_DATA_REG);
+ if (xfer->tx_buf) {
+ memcpy(&reg_val, xfer->tx_buf + (cnt * 4), remainder);
+ writel(reg_val, mdata->base + SPI_TX_DATA_REG);
+ }
+ if (xfer->rx_buf) {
+ reg_val = readl(mdata->base + SPI_RX_DATA_REG);
+ memcpy(xfer->rx_buf + (cnt * 4), &reg_val, remainder);
+ }
}

mtk_spi_enable_transfer(master);
--
2.25.1