tpm_tis: Use timeouts returned from TPM

The current TPM TIS driver in git discards the timeout values returned
from the TPM. The check of the response packet needs to consider that
the return_code field is 0 on success and the size of the expected
packet is equivalent to the header size + u32 length indicator for the
TPM_GetCapability() result + 3 timeout indicators of type u32.

I am also adding a sysfs entry 'timeouts' showing the timeouts that are
being used.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Tested-by: Guillaume Chazarain <guichaz@gmail.com>
Signed-off-by: Rajiv Andrade <srajiv@linux.vnet.ibm.com>

1 files changed, 16 insertions, 2 deletions

diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 36e0fa161c2b..faf5a2c65926 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -577,9 +577,11 @@ duration:
         if (rc)
                 return;
 
-        if (be32_to_cpu(tpm_cmd.header.out.return_code)
-            != 3 * sizeof(u32))
+        if (be32_to_cpu(tpm_cmd.header.out.return_code) != 0 ||
+            be32_to_cpu(tpm_cmd.header.out.length)
+            != sizeof(tpm_cmd.header.out) + sizeof(u32) + 3 * sizeof(u32))
                 return;
+
         duration_cap = &tpm_cmd.params.getcap_out.cap.duration;
         chip->vendor.duration[TPM_SHORT] =
             usecs_to_jiffies(be32_to_cpu(duration_cap->tpm_short));
@@ -939,6 +941,18 @@ ssize_t tpm_show_caps_1_2(struct device * dev,
 }
 EXPORT_SYMBOL_GPL(tpm_show_caps_1_2);
 
+ssize_t tpm_show_timeouts(struct device *dev, struct device_attribute *attr,
+                          char *buf)
+{
+        struct tpm_chip *chip = dev_get_drvdata(dev);
+
+        return sprintf(buf, "%d %d %d\n",
+                       jiffies_to_usecs(chip->vendor.duration[TPM_SHORT]),
+                       jiffies_to_usecs(chip->vendor.duration[TPM_MEDIUM]),
+                       jiffies_to_usecs(chip->vendor.duration[TPM_LONG]));
+}
+EXPORT_SYMBOL_GPL(tpm_show_timeouts);
+
 ssize_t tpm_store_cancel(struct device *dev, struct device_attribute *attr,
                         const char *buf, size_t count)
 {