ACPI: PM: Introduce acpi_dev_power_up_children_with_adr()

Introduce a function powering up all of the children of a given ACPI
device object that are power-manageable and hold valid _ADR ACPI
objects so as to make it possible to prepare the corresponding
"physical" devices for enumeration carried out by a bus type driver,
like PCI.

This function will be used in a subsequent change set.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

drivers/acpi/device_pm.c

@@ -425,6 +425,36 @@ bool acpi_bus_power_manageable(acpi_handle handle)
 }
 EXPORT_SYMBOL(acpi_bus_power_manageable);
 
+static int acpi_power_up_if_adr_present(struct device *dev, void *not_used)
+{
+	struct acpi_device *adev;
+
+	adev = to_acpi_device(dev);
+	if (!(adev->flags.power_manageable && adev->pnp.type.bus_address))
+		return 0;
+
+	acpi_handle_debug(adev->handle, "Power state: %s\n",
+			  acpi_power_state_string(adev->power.state));
+
+	if (adev->power.state == ACPI_STATE_D3_COLD)
+		return acpi_device_set_power(adev, ACPI_STATE_D0);
+
+	return 0;
+}
+
+/**
+ * acpi_dev_power_up_children_with_adr - Power up childres with valid _ADR
+ * @adev: Parent ACPI device object.
+ *
+ * Change the power states of the direct children of @adev that are in D3cold
+ * and hold valid _ADR objects to D0 in order to allow bus (e.g. PCI)
+ * enumeration code to access them.
+ */
+void acpi_dev_power_up_children_with_adr(struct acpi_device *adev)
+{
+	acpi_dev_for_each_child(adev, acpi_power_up_if_adr_present, NULL);
+}
+
 #ifdef CONFIG_PM
 static DEFINE_MUTEX(acpi_pm_notifier_lock);
 static DEFINE_MUTEX(acpi_pm_notifier_install_lock);

include/acpi/acpi_bus.h

@@ -524,6 +524,7 @@ int acpi_device_fix_up_power(struct acpi_device *device);
 int acpi_bus_update_power(acpi_handle handle, int *state_p);
 int acpi_device_update_power(struct acpi_device *device, int *state_p);
 bool acpi_bus_power_manageable(acpi_handle handle);
+void acpi_dev_power_up_children_with_adr(struct acpi_device *adev);
 int acpi_device_power_add_dependent(struct acpi_device *adev,
 				    struct device *dev);
 void acpi_device_power_remove_dependent(struct acpi_device *adev,