Re: [PATCH 3/5] tpm_tis_spi: Check correct byte for wait state indicator
From: Jarkko Sakkinen <hidden>
Date: 2017-02-24 13:12:20
Also in:
lkml
On Thu, Feb 16, 2017 at 04:08:24PM +0000, Peter Huewe wrote:
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: <redacted>
Fixes: 0edbfea537d1 ("tpm/tpm_tis_spi: Add support for spi phy")
Signed-off-by: Alexander Steffen <redacted>
Signed-off-by: Peter Huewe <redacted>Reviewed-by: Jarkko Sakkien <redacted> /Jarkko
quoted hunk ↗ jump to hunk
--- 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