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Subject[PATCH v2] platform/chrome: Expose resume result via debugfs
Date
For ECs that support it, the EC returns the number of slp_s0
transitions and whether or not there was a timeout in the resume
response. Expose the last resume result to usermode via debugfs so
that usermode can detect and report S0ix timeouts.

Signed-off-by: Evan Green <evgreen@chromium.org>
---

Changes in v2:
- Moved from sysfs to debugfs (Enric)
- Added documentation (Enric)


---
Documentation/ABI/testing/debugfs-cros-ec | 22 ++++++++++++++++++++++
drivers/mfd/cros_ec.c | 6 +++++-
drivers/platform/chrome/cros_ec_debugfs.c | 7 +++++++
include/linux/mfd/cros_ec.h | 1 +
4 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/debugfs-cros-ec b/Documentation/ABI/testing/debugfs-cros-ec
index 573a82d23c89..008b31422079 100644
--- a/Documentation/ABI/testing/debugfs-cros-ec
+++ b/Documentation/ABI/testing/debugfs-cros-ec
@@ -32,3 +32,25 @@ Description:
is used for synchronizing the AP host time with the EC
log. An error is returned if the command is not supported
by the EC or there is a communication problem.
+
+What: /sys/kernel/debug/cros_ec/last_resume_result
+Date: June 2019
+KernelVersion: 5.3
+Description:
+ Some ECs have a feature where they will track transitions to
+ the (Intel) processor's SLP_S0 line, in order to detect cases
+ where a system failed to go into S0ix. When the system resumes,
+ an EC with this feature will return a summary of SLP_S0
+ transitions that occurred. The last_resume_result file returns
+ the most recent response from the AP's resume message to the EC.
+
+ The bottom 31 bits contain a count of the number of SLP_S0
+ transitions that occurred since the suspend message was
+ received. Bit 31 is set if the EC attempted to wake the
+ system due to a timeout when watching for SLP_S0 transitions.
+ Callers can use this to detect a wake from the EC due to
+ S0ix timeouts. The result will be zero if no suspend
+ transitions have been attempted, or the EC does not support
+ this feature.
+
+ Output will be in the format: "0x%08x\n".
diff --git a/drivers/mfd/cros_ec.c b/drivers/mfd/cros_ec.c
index 5d5c41ac3845..2a9ac5213893 100644
--- a/drivers/mfd/cros_ec.c
+++ b/drivers/mfd/cros_ec.c
@@ -102,12 +102,16 @@ static int cros_ec_sleep_event(struct cros_ec_device *ec_dev, u8 sleep_event)

/* For now, report failure to transition to S0ix with a warning. */
if (ret >= 0 && ec_dev->host_sleep_v1 &&
- (sleep_event == HOST_SLEEP_EVENT_S0IX_RESUME))
+ (sleep_event == HOST_SLEEP_EVENT_S0IX_RESUME)) {
+ ec_dev->last_resume_result =
+ buf.u.resp1.resume_response.sleep_transitions;
+
WARN_ONCE(buf.u.resp1.resume_response.sleep_transitions &
EC_HOST_RESUME_SLEEP_TIMEOUT,
"EC detected sleep transition timeout. Total slp_s0 transitions: %d",
buf.u.resp1.resume_response.sleep_transitions &
EC_HOST_RESUME_SLEEP_TRANSITIONS_MASK);
+ }

return ret;
}
diff --git a/drivers/platform/chrome/cros_ec_debugfs.c b/drivers/platform/chrome/cros_ec_debugfs.c
index cd3fb9c22a44..663bebf699bf 100644
--- a/drivers/platform/chrome/cros_ec_debugfs.c
+++ b/drivers/platform/chrome/cros_ec_debugfs.c
@@ -447,6 +447,13 @@ static int cros_ec_debugfs_probe(struct platform_device *pd)
debugfs_create_file("uptime", 0444, debug_info->dir, debug_info,
&cros_ec_uptime_fops);

+ if (!strcmp(ec->class_dev.kobj.name, CROS_EC_DEV_NAME)) {
+ debugfs_create_x32("last_resume_result",
+ 0444,
+ debug_info->dir,
+ &ec->ec_dev->last_resume_result);
+ }
+
ec->debug_info = debug_info;

dev_set_drvdata(&pd->dev, ec);
diff --git a/include/linux/mfd/cros_ec.h b/include/linux/mfd/cros_ec.h
index 5ddca44be06d..45aba26db964 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/include/linux/mfd/cros_ec.h
@@ -155,6 +155,7 @@ struct cros_ec_device {
struct ec_response_get_next_event_v1 event_data;
int event_size;
u32 host_event_wake_mask;
+ u32 last_resume_result;
};

/**
--
2.20.1
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