PM / sleep: Report interrupt that caused system wakeup

Add a sysfs attribute, /sys/power/pm_wakeup_irq, reporting the IRQ
number of the first wakeup interrupt (that is, the first interrupt
from an IRQ line armed for system wakeup) seen by the kernel during
the most recent system suspend/resume cycle.

This feature will be useful for system wakeup diagnostics of
spurious wakeup interrupts.

Signed-off-by: Alexandra Yates <alexandra.yates@linux.intel.com>
[ rjw: Fixed up pm_wakeup_irq definition ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/kernel/power/main.c b/kernel/power/main.c
index 63d395b5df93..b2dd4d999900 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -272,6 +272,22 @@ static inline void pm_print_times_init(void)
 {
         pm_print_times_enabled = !!initcall_debug;
 }
+
+static ssize_t pm_wakeup_irq_show(struct kobject *kobj,
+                                        struct kobj_attribute *attr,
+                                        char *buf)
+{
+        return pm_wakeup_irq ? sprintf(buf, "%u\n", pm_wakeup_irq) : -ENODATA;
+}
+
+static ssize_t pm_wakeup_irq_store(struct kobject *kobj,
+                                        struct kobj_attribute *attr,
+                                        const char *buf, size_t n)
+{
+        return -EINVAL;
+}
+power_attr(pm_wakeup_irq);
+
 #else /* !CONFIG_PM_SLEEP_DEBUG */
 static inline void pm_print_times_init(void) {}
 #endif /* CONFIG_PM_SLEEP_DEBUG */
@@ -604,6 +620,7 @@ static struct attribute * g[] = {
 #endif
 #ifdef CONFIG_PM_SLEEP_DEBUG
         &pm_print_times_attr.attr,
+        &pm_wakeup_irq_attr.attr,
 #endif
 #endif
 #ifdef CONFIG_FREEZER