Wait states are signaled in the last byte received from the TPM in
response to the header, not the first byte. Check rx_buf[3] instead of
rx_buf[0].
Cc: <stable@xxxxxxxxxxxxxxx>
Fixes: 0edbfea537d1 ("tpm/tpm_tis_spi: Add support for spi phy")
Signed-off-by: Alexander Steffen <Alexander.Steffen@xxxxxxxxxxxx>
Signed-off-by: Peter Huewe <peter.huewe@xxxxxxxxxxxx>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
Tested-by: Benoit Houyere <benoit.houyere@xxxxxx>
---
drivers/char/tpm/tpm_tis_spi.c | 36 ++++++++++++++++++------------------
1 file changed, 18 insertions(+), 18 deletions(-)
diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
index 639614f2d415..62f50b6c9ef6 100644
--- a/drivers/char/tpm/tpm_tis_spi.c
+++ b/drivers/char/tpm/tpm_tis_spi.c
@@ -85,25 +85,25 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u16 len,
if (ret < 0)
goto exit;
- phy->tx_buf[0] = 0;
-
- /* According to TCG PTP specification, if there is no TPM present at
- * all, then the design has a weak pull-up on MISO. If a TPM is not
- * present, a pull-up on MISO means that the SB controller sees a 1,
- * and will latch in 0xFF on the read.
- */
- for (i = 0; (phy->rx_buf[0] & 0x01) == 0 && i < TPM_RETRY; i++) {
- spi_xfer.len = 1;
- spi_message_init(&m);
- spi_message_add_tail(&spi_xfer, &m);
- ret = spi_sync_locked(phy->spi_device, &m);
- if (ret < 0)
+ if ((phy->rx_buf[3] & 0x01) == 0) {
+ // handle SPI wait states
+ phy->tx_buf[0] = 0;
+
+ for (i = 0; i < TPM_RETRY; i++) {
+ spi_xfer.len = 1;
+ spi_message_init(&m);
+ spi_message_add_tail(&spi_xfer, &m);
+ ret = spi_sync_locked(phy->spi_device, &m);
+ if (ret < 0)
+ goto exit;
+ if (phy->rx_buf[0] & 0x01)
+ break;
+ }
+
+ if (i == TPM_RETRY) {
+ ret = -ETIMEDOUT;
goto exit;
- }
-
- if (i == TPM_RETRY) {
- ret = -ETIMEDOUT;
- goto exit;
+ }
}
spi_xfer.cs_change = 0;
--
2.7.4