lkml.org 
[lkml]   [2017]   [Feb]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3/5] tpm_tis_spi: Check correct byte for wait state indicator
Date
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@vger.kernel.org>
Fixes: 0edbfea537d1 ("tpm/tpm_tis_spi: Add support for spi phy")
Signed-off-by: Alexander Steffen <Alexander.Steffen@infineon.com>
Signed-off-by: Peter Huewe <peter.huewe@infineon.com>
---
drivers/char/tpm/tpm_tis_spi.c | 40 +++++++++++++++++++++-------------------
1 file changed, 21 insertions(+), 19 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_spi.c b/drivers/char/tpm/tpm_tis_spi.c
index d782b9974c14..16938e2253d2 100644
--- a/drivers/char/tpm/tpm_tis_spi.c
+++ b/drivers/char/tpm/tpm_tis_spi.c
@@ -60,7 +60,7 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u8 len,
u8 *buffer, u8 direction)
{
struct tpm_tis_spi_phy *phy = to_tpm_tis_spi_phy(data);
- int ret, i;
+ int ret;
struct spi_message m;
struct spi_transfer spi_xfer = {
.tx_buf = phy->tx_buf,
@@ -85,25 +85,27 @@ static int tpm_tis_spi_transfer(struct tpm_tis_data *data, u32 addr, u8 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
+ int i;
+
+ 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
\
 
 \ /
  Last update: 2017-02-16 17:10    [W:0.857 / U:0.724 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site