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 2c3435d55d010032cbe800d31b4de9639b77aa5f..305d6dd6bdefaf0b7343e852fa54a14d7450111c 100644 (file)
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -15,6 +15,7 @@
 #include <linux/seq_file.h>
 #include <linux/debugfs.h>
 #include <linux/pm_wakeirq.h>
+#include <linux/types.h>
 #include <trace/events/power.h>
 
 #include "power.h"
@@ -806,16 +807,31 @@ 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);