Re: [PATCH 1/2] TPM: sysfs functions consolidation
From: Rajiv Andrade
Date: Fri Jan 30 2009 - 09:45:28 EST
Matt Helsley wrote:
On Thu, 2009-01-29 at 21:01 -0200, Rajiv Andrade wrote:
According to Dave Hansen's comments on the tpm_show_*, some of these functions
present a pattern when allocating data[] memory space and also when setting its
content. A new function was created so that this pattern could be consolidated.
Also, replaced the data[] command vectors and its indexes by meaningful structures
as pointed out by Matt Helsley too.
Signed-off-by: Rajiv Andrade <srajiv@xxxxxxxxxxxxxxxxxx>
---
drivers/char/tpm/tpm.c | 410 +++++++++++++++++-------------------------------
drivers/char/tpm/tpm.h | 117 ++++++++++++++
2 files changed, 258 insertions(+), 269 deletions(-)
diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 9c47dc4..58ea16f 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
<snip>
- rc = transmit_cmd(chip, data, sizeof(data),
+ rc = transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
"attempting to determine the timeouts");
if (rc)
goto duration;
- if (be32_to_cpu(*((__be32 *) (data + TPM_GET_CAP_RET_SIZE_IDX)))
+ if (be32_to_cpu(tpm_cmd.header.out.length)
!= 4 * sizeof(u32))
goto duration;
+ timeout_cap = &tpm_cmd.params.getcap_out.cap.timeout;
/* Don't overwrite default if value is 0 */
- timeout =
- be32_to_cpu(*((__be32 *) (data + TPM_GET_CAP_RET_UINT32_1_IDX)));
+ timeout = be32_to_cpu(timeout_cap->a);
if (timeout)
chip->vendor.timeout_a = usecs_to_jiffies(timeout);
- timeout =
- be32_to_cpu(*((__be32 *) (data + TPM_GET_CAP_RET_UINT32_2_IDX)));
+ timeout = be32_to_cpu(timeout_cap->b);
if (timeout)
chip->vendor.timeout_b = usecs_to_jiffies(timeout);
- timeout =
- be32_to_cpu(*((__be32 *) (data + TPM_GET_CAP_RET_UINT32_3_IDX)));
+ timeout = be32_to_cpu(timeout_cap->c);
if (timeout)
chip->vendor.timeout_c = usecs_to_jiffies(timeout);
- timeout =
- be32_to_cpu(*((__be32 *) (data + TPM_GET_CAP_RET_UINT32_4_IDX)));
+ timeout = be32_to_cpu(timeout_cap->d);
if (timeout)
chip->vendor.timeout_d = usecs_to_jiffies(timeout);
Are jiffies really the appropriate units of time for the needs of this
driver? I could easily be wrong but I thought most drivers were
discouraged from using jiffies since HZ is configurable...
The timeout is converted from usecs to jiffies before assigning it to
chip->vendor.timeout_*, so even with boxes with different configured HZ,
those values would be the same in usecs.
Hopefully there's no way to modify HZ in runtime.
duration:
- memcpy(data, tpm_cap, sizeof(tpm_cap));
- data[TPM_CAP_IDX] = TPM_CAP_PROP;
- data[TPM_CAP_SUBCAP_IDX] = TPM_CAP_PROP_TIS_DURATION;
+ tpm_cmd.header.in = tpm_getcap_header;
+ tpm_cmd.params.getcap_in.cap = TPM_CAP_PROP;
+ tpm_cmd.params.getcap_in.subcap_size = cpu_to_be32(4);
+ tpm_cmd.params.getcap_in.subcap = TPM_CAP_PROP_TIS_DURATION;
- rc = transmit_cmd(chip, data, sizeof(data),
+ rc = transmit_cmd(chip, &tpm_cmd, TPM_INTERNAL_RESULT_SIZE,
"attempting to determine the durations");
if (rc)
return;
- if (be32_to_cpu(*((__be32 *) (data + TPM_GET_CAP_RET_SIZE_IDX)))
+ if (be32_to_cpu(tpm_cmd.header.out.return_code)
!= 3 * sizeof(u32))
return;
-
+ timeout_cap = &tpm_cmd.params.getcap_out.cap.timeout;
chip->vendor.duration[TPM_SHORT] =
- usecs_to_jiffies(be32_to_cpu
- (*((__be32 *) (data +
- TPM_GET_CAP_RET_UINT32_1_IDX))));
+ usecs_to_jiffies(be32_to_cpu(timeout_cap->a));
/* The Broadcom BCM0102 chipset in a Dell Latitude D820 gets the above
* value wrong and apparently reports msecs rather than usecs. So we
* fix up the resulting too-small TPM_SHORT value to make things work.
@@ -565,13 +578,9 @@ duration:
chip->vendor.duration[TPM_SHORT] = HZ;
chip->vendor.duration[TPM_MEDIUM] =
- usecs_to_jiffies(be32_to_cpu
- (*((__be32 *) (data +
- TPM_GET_CAP_RET_UINT32_2_IDX))));
+ usecs_to_jiffies(be32_to_cpu(timeout_cap->b));
chip->vendor.duration[TPM_LONG] =
- usecs_to_jiffies(be32_to_cpu
- (*((__be32 *) (data +
- TPM_GET_CAP_RET_UINT32_3_IDX))));
+ usecs_to_jiffies(be32_to_cpu(timeout_cap->c));
OK, so it looks like these timeouts are short, medium, and long-duration
timeouts and those correspond to "a", "b", and "c". What's "d"? Also
this suggests slightly-better names for these fields. If you can think
of short names suggesting why these separate, varying-length timeouts
are needed that could be even better.
<snip>
Yes, the timeout_cap struct isn't appropriate here to read the
TIS_DURATION capability, which has a different meaning from the timeout
one and hasn't a forth field to be assigned. I'll write the duration_cap
struct and make use of it here and resubmit this patch.
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 8e30df4..867987d 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
<snip>
+struct timeout_t {
+ __be32 a;
+ __be32 b;
+ __be32 c;
+ __be32 d;
+}__attribute__((packed));
As I pointed out above I think these could use better names. I also
noticed that there are timeout_a, timeout_b, etc. fields of another
struct (somewhere under "chips" if I recall..). Perhaps similar naming
-- maybe even this struct -- should be (re)used?
<snip>
Yes, it's inside tpm_vendor_specific struct, but this one has __be32
fields. The tpm_vendor_specific struct has these timeout fields and but
also a bunch of others, so unfortunately no reuse could be done.
Thanks reviewing it,
Rajiv
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