[PATCH 5.17 0869/1126] spi: fsi: Implement a timeout for polling status

Greg Kroah-Hartman
2022-04-05T09:52:28Z

From: Eddie James <eajames@linux.ibm.com>

[ Upstream commit 89b35e3f28514087d3f1e28e8f5634fbfd07c554 ]

The data transfer routines must poll the status register to
determine when more data can be shifted in or out. If the hardware
gets into a bad state, these polling loops may never exit. Prevent
this by returning an error if a timeout is exceeded.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20220317211426.38940-1-eajames@linux.ibm.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/spi/spi-fsi.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/spi/spi-fsi.c b/drivers/spi/spi-fsi.c
index b6c7467f0b59..d403a7a3021d 100644
--- a/drivers/spi/spi-fsi.c
+++ b/drivers/spi/spi-fsi.c
@@ -25,6 +25,7 @@

#define SPI_FSI_BASE 0x70000
#define SPI_FSI_INIT_TIMEOUT_MS 1000
+#define SPI_FSI_STATUS_TIMEOUT_MS 100
#define SPI_FSI_MAX_RX_SIZE 8
#define SPI_FSI_MAX_TX_SIZE 40

@@ -299,6 +300,7 @@ static int fsi_spi_transfer_data(struct fsi_spi *ctx,
struct spi_transfer *transfer)
{
int rc = 0;
+ unsigned long end;
u64 status = 0ULL;

if (transfer->tx_buf) {
@@ -315,10 +317,14 @@ static int fsi_spi_transfer_data(struct fsi_spi *ctx,
if (rc)
return rc;

+ end = jiffies + msecs_to_jiffies(SPI_FSI_STATUS_TIMEOUT_MS);
do {
rc = fsi_spi_status(ctx, &status, "TX");
if (rc)
return rc;
+
+ if (time_after(jiffies, end))
+ return -ETIMEDOUT;
} while (status & SPI_FSI_STATUS_TDR_FULL);

sent += nb;
@@ -329,10 +335,14 @@ static int fsi_spi_transfer_data(struct fsi_spi *ctx,
u8 *rx = transfer->rx_buf;

while (transfer->len > recv) {
+ end = jiffies + msecs_to_jiffies(SPI_FSI_STATUS_TIMEOUT_MS);
do {
rc = fsi_spi_status(ctx, &status, "RX");
if (rc)
return rc;
+
+ if (time_after(jiffies, end))
+ return -ETIMEDOUT;
} while (!(status & SPI_FSI_STATUS_RDR_FULL));

rc = fsi_spi_read_reg(ctx, SPI_FSI_DATA_RX, &in);
--
2.34.1