spi: fsi: Implement a timeout for polling status

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>

diff --git a/drivers/spi/spi-fsi.c b/drivers/spi/spi-fsi.c
index b6c7467f0b590db18a7497850ff81082a8d27490..d403a7a3021d0067028d3aaba58a0ee4d3d7902b 100644 (file)
--- 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);