[coreboot-gerrit] Change in coreboot[master]: spi/tpm.c do not waste time on wake pulses unless necessary
Vadim Bendebury (Code Review)
gerrit at coreboot.org
Fri Nov 3 21:35:26 CET 2017
Vadim Bendebury has uploaded this change for review. ( https://review.coreboot.org/22321
Change subject: spi/tpm.c do not waste time on wake pulses unless necessary
......................................................................
spi/tpm.c do not waste time on wake pulses unless necessary
The Cr50 secure chip implementation is guaranteed not to fall asleep
for 1 second after any SPI slave activity.
Let's not waste time on the wake up ping when it is not necessary.
BRANCH=cr50
BUG=b:68012381
TEST=using a protocol analyzer verified that the wake pulses are
generated only when the new Coreboot stage or Depthcharge start,
not on every SPI slave transaction.
Change-Id: Id8def1470ba3eab533075b9e7180f8a58e0b00b6
Signed-off-by: Vadim Bendebury <vbendeb at chromium.org>
---
M src/drivers/spi/tpm/tpm.c
1 file changed, 28 insertions(+), 5 deletions(-)
git pull ssh://review.coreboot.org:29418/coreboot refs/changes/21/22321/1
diff --git a/src/drivers/spi/tpm/tpm.c b/src/drivers/spi/tpm/tpm.c
index 58bf842..c47b807 100644
--- a/src/drivers/spi/tpm/tpm.c
+++ b/src/drivers/spi/tpm/tpm.c
@@ -109,6 +109,9 @@
struct stopwatch sw;
static int tpm_sync_needed CAR_GLOBAL;
struct spi_slave *spi_slave = car_get_var_ptr(&g_spi_slave);
+ int wakeup_needed = 1;
+ static long prev_us CAR_GLOBAL;
+ struct mono_time mt;
/* Wait for tpm to finish previous transaction if needed */
if (car_get_var(tpm_sync_needed))
@@ -116,11 +119,31 @@
else
car_set_var(tpm_sync_needed, 1);
- /* Try to wake cr50 if it is asleep. */
- spi_claim_bus(spi_slave);
- udelay(1);
- spi_release_bus(spi_slave);
- udelay(100);
+ if (IS_ENABLED(CONFIG_HAVE_MONOTONIC_TIMER)) {
+ timer_monotonic_get(&mt);
+
+ if (car_get_var(prev_us))
+ /*
+ * If there is a timestamp, check if SPI slave timeout
+ * has expired.
+ *
+ * The Cr50 on H1 does not go to sleep for 1 second
+ * after any SPI slave activity, let's be conservative
+ * and limit the window to 900 ms.
+ */
+ if (mt.microseconds <
+ (car_get_var(prev_us) + 900 * 1000))
+ wakeup_needed = 0;
+ car_set_var(prev_us, mt.microseconds);
+ }
+
+ if (wakeup_needed) {
+ /* Just in case Cr50 is asleep. */
+ spi_claim_bus(spi_slave);
+ udelay(1);
+ spi_release_bus(spi_slave);
+ udelay(100);
+ }
/*
* The first byte of the frame header encodes the transaction type
--
To view, visit https://review.coreboot.org/22321
To unsubscribe, visit https://review.coreboot.org/settings
Gerrit-Project: coreboot
Gerrit-Branch: master
Gerrit-MessageType: newchange
Gerrit-Change-Id: Id8def1470ba3eab533075b9e7180f8a58e0b00b6
Gerrit-Change-Number: 22321
Gerrit-PatchSet: 1
Gerrit-Owner: Vadim Bendebury <vbendeb at chromium.org>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.coreboot.org/pipermail/coreboot-gerrit/attachments/20171103/7e03972c/attachment-0001.html>
More information about the coreboot-gerrit
mailing list