4 files changed, 31 insertions, 1 deletions

diff --git a/Documentation/ABI/testing/debugfs-cros-ec b/Documentation/ABI/testing/debugfs-cros-ec
index 573a82d23c89..1fe0add99a2a 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-device>/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 bd2bcdd4718b..64a2d3adc729 100644
--- a/drivers/mfd/cros_ec.c
+++ b/drivers/mfd/cros_ec.c
@@ -110,12 +110,16 @@ 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 7ee060743844..8ec1cc2889f2 100644
--- a/drivers/platform/chrome/cros_ec_debugfs.c
+++ b/drivers/platform/chrome/cros_ec_debugfs.c
@@ -447,6 +447,9 @@ static int cros_ec_debugfs_probe(struct platform_device *pd)
         debugfs_create_file("uptime", 0444, debug_info->dir, debug_info,
                             &cros_ec_uptime_fops);
 
+        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 cfa78bb4990f..d50ade418a83 100644
--- a/include/linux/mfd/cros_ec.h
+++ b/include/linux/mfd/cros_ec.h
@@ -163,6 +163,7 @@ 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;
 };
 
 /**