ACPI: Use system level attribute of wakeup power resources

The system level attribute of ACPI power resources is the lowest
system sleep level (S0, S2 etc.) in which the given resource can be
"on" (ACPI 5.0, Section 7.1).  On the other hand, wakeup power
resources have to be "on" for devices depending on them to be able to
signal wakeup.  Therefore devices cannot wake up the system from
sleep states higher than the minimum of the system level attributes
of their wakeup power resources.

Use the wakeup power resources' system level values to get the
deepest system sleep state (highest system sleep level) the given
device can wake up the system from.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/acpi/power.c b/drivers/acpi/power.c
index 1600f753fafe..089a7c39348f 100644
--- a/drivers/acpi/power.c
+++ b/drivers/acpi/power.c
@@ -429,6 +429,20 @@ void acpi_power_add_remove_device(struct acpi_device *adev, bool add)
         }
 }
 
+int acpi_power_min_system_level(struct list_head *list)
+{
+        struct acpi_power_resource_entry *entry;
+        int system_level = 5;
+
+        list_for_each_entry(entry, list, node) {
+                struct acpi_power_resource *resource = entry->resource;
+
+                if (system_level > resource->system_level)
+                        system_level = resource->system_level;
+        }
+        return system_level;
+}
+
 /* --------------------------------------------------------------------------
                              Device Power Management
    -------------------------------------------------------------------------- */