[PATCH v5 4/5] PM: hibernate: add new api pm_hibernate_is_recovering()

[Samuel Zhang <guoqing.zhang@amd.com>]

dev_pm_ops.thaw() is called in following cases:
* normal case: after hibernation image has been created.
* error case 1: creation of a hibernation image has failed.
* error case 2: restoration from a hibernation image has failed.

For normal case, it is called mainly for resume storage devices for
saving the hibernation image. Other devices that are not involved
in the image saving do not need to resume the device. But since there's
no api to know which case thaw() is called, device drivers can't
conditionally resume device in thaw().

The new pm_hibernate_is_recovering() is such a api to query if thaw() is
called in normal case.

Signed-off-by: Samuel Zhang <guoqing.zhang@amd.com>
---
 drivers/base/power/main.c | 14 ++++++++++++++
 include/linux/pm.h        |  2 ++
 2 files changed, 16 insertions(+)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index 40e1d8d8a589..ff78cf96f795 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -63,6 +63,20 @@ static LIST_HEAD(dpm_noirq_list);
 static DEFINE_MUTEX(dpm_list_mtx);
 static pm_message_t pm_transition;
 
+/**
+ * pm_hibernate_is_recovering - if recovering from hibernate due to error.
+ *
+ * Used to query if dev_pm_ops.thaw() is called for normal hibernation case or
+ * recovering from some error.
+ *
+ * Return: true for error case, false for normal case.
+ */
+bool pm_hibernate_is_recovering(void)
+{
+	return pm_transition.event == PM_EVENT_RECOVER;
+}
+EXPORT_SYMBOL_GPL(pm_hibernate_is_recovering);
+
 static int async_error;
 
 static const char *pm_verb(int event)
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 78855d794342..f54a803f2afb 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -657,6 +657,8 @@ struct pm_subsys_data {
 #define DPM_FLAG_SMART_SUSPEND		BIT(2)
 #define DPM_FLAG_MAY_SKIP_RESUME	BIT(3)
 
+bool pm_hibernate_is_recovering(void);
+
 struct dev_pm_info {
 	pm_message_t		power_state;
 	bool			can_wakeup:1;
-- 
2.43.5