wakeup: Add last wake up source logging for suspend abort reason.

There is a possibility that a wakeup source event is received after
the device prepares to suspend which might cause the suspend to abort.

This patch adds the functionality of reporting the last active wakeup
source which is currently not active but caused the suspend to abort reason
via the /sys/kernel/power/last_wakeup_reason file.

Change-Id: I1760d462f497b33e425f5565cb6cff5973932ec3
Signed-off-by: Ruchi Kandoi <kandoiruchi@google.com>

diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index bea700736f2476f8de18f943ec1090b82d11bd37..4b35cc08c3b6b3e9491e95858d07ed5ed243902d 100644 (file)
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -14,6 +14,7 @@
 #include <linux/suspend.h>
 #include <linux/seq_file.h>
 #include <linux/debugfs.h>
+#include <linux/types.h>
 #include <trace/events/power.h>
 
 #include "power.h"
@@ -661,16 +662,31 @@ EXPORT_SYMBOL_GPL(pm_wakeup_event);
 
 void pm_get_active_wakeup_sources(char *pending_wakeup_source, size_t max)
 {
-       struct wakeup_source *ws;
+       struct wakeup_source *ws, *last_active_ws = NULL;
        int len = 0;
+       bool active = false;
+
        rcu_read_lock();
-       len += snprintf(pending_wakeup_source, max, "Pending Wakeup Sources: ");
        list_for_each_entry_rcu(ws, &wakeup_sources, entry) {
                if (ws->active) {
-                       len += snprintf(pending_wakeup_source + len, max,
+                       if (!active)
+                               len += scnprintf(pending_wakeup_source, max,
+                                               "Pending Wakeup Sources: ");
+                       len += scnprintf(pending_wakeup_source + len, max - len,
                                "%s ", ws->name);
+                       active = true;
+               } else if (!active &&
+                          (!last_active_ws ||
+                           ktime_to_ns(ws->last_time) >
+                           ktime_to_ns(last_active_ws->last_time))) {
+                       last_active_ws = ws;
                }
        }
+       if (!active && last_active_ws) {
+               scnprintf(pending_wakeup_source, max,
+                               "Last active Wakeup Source: %s",
+                               last_active_ws->name);
+       }
        rcu_read_unlock();
 }
 EXPORT_SYMBOL_GPL(pm_get_active_wakeup_sources);