On 03/02/2018 11:05 AM, Kevin O'Connor wrote:
On Tue, Feb 27, 2018 at 02:17:10PM -0500, Stephen Douthit wrote:
This is based on wait_startup() from the Linux tpm_tis driver.

Signed-off-by: Stephen Douthit <steph...@silicom-usa.com>
Tested-by: Stephen Douthit <steph...@silicom-usa.com>
---
  src/hw/tpm_drivers.c | 13 ++++++++++++-
  1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/hw/tpm_drivers.c b/src/hw/tpm_drivers.c
index 13ad821..da8bb63 100644
--- a/src/hw/tpm_drivers.c
+++ b/src/hw/tpm_drivers.c
@@ -86,6 +86,11 @@ static u32 wait_reg8(u8* reg, u32 time, u8 mask, u8 expect)
      return rc;
  }
+static u32 tis_wait_access(u8 locty, u32 time, u8 mask, u8 expect)
+{
+    return wait_reg8(TIS_REG(locty, TIS_REG_ACCESS), time, mask, expect);
+}
+
  static u32 tis_wait_sts(u8 locty, u32 time, u8 mask, u8 expect)
  {
      return wait_reg8(TIS_REG(locty, TIS_REG_STS), time, mask, expect);
@@ -102,7 +107,13 @@ static u32 tis_probe(void)
      if (!CONFIG_TCGBIOS)
          return 0;
- u32 rc = 0;
+    /* Wait for the interface to report it's ready */
+    u32 rc = tis_wait_access(0, TIS_DEFAULT_TIMEOUT_A,
+                             TIS_ACCESS_TPM_REG_VALID_STS,
+                             TIS_ACCESS_TPM_REG_VALID_STS);
+    if (rc)
+        return 0;
+

Thanks.  I was about to commit this when I noticed the above.  In the
case where tis_wait_access() fails due to a timeout, shouldn't
tis_probe() return an error indicator instead of success?

tis_probe() returns 0 for no device, '1' for device present.

Take a look at the usage in tpmhw_probe(), or the comment on
tis_probe() itself.

Thanks,
Steve

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