ACPI: property: Allow making references to non-device nodes

Implement references to non-device nodes using the first package
entry in the hierarchical data extension reference, the second one
being the name of the referred object.

The data node references are parsed just after the device arguments
before the integer arguments. If there are no strings after the
device arguments, the parsing works exactly as it used to be.

Referring to a data node called "node" under device DEV, with
integer arguments 0, 2 would thus look like:

	Package() { DEV, "node", 0, 2 }

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/property.c

@@ -542,6 +542,23 @@ static int acpi_data_get_property_array(const struct acpi_device_data *data,
 	return 0;
 }
 
+static struct fwnode_handle *
+acpi_fwnode_get_named_child_node(const struct fwnode_handle *fwnode,
+				 const char *childname)
+{
+	struct fwnode_handle *child;
+
+	/*
+	 * Find first matching named child node of this fwnode.
+	 * For ACPI this will be a data only sub-node.
+	 */
+	fwnode_for_each_child_node(fwnode, child)
+		if (acpi_data_node_match(child, childname))
+			return child;
+
+	return NULL;
+}
+
 /**
  * __acpi_node_get_property_reference - returns handle to the referenced object
  * @fwnode: Firmware node to get the property from
@@ -633,6 +650,8 @@ int __acpi_node_get_property_reference(const struct fwnode_handle *fwnode,
 		u32 nargs, i;
 
 		if (element->type == ACPI_TYPE_LOCAL_REFERENCE) {
+			struct fwnode_handle *ref_fwnode;
+
 			ret = acpi_bus_get_device(element->reference.handle,
 						  &device);
 			if (ret)
@@ -641,6 +660,19 @@ int __acpi_node_get_property_reference(const struct fwnode_handle *fwnode,
 			nargs = 0;
 			element++;
 
+			/*
+			 * Find the referred data extension node under the
+			 * referred device node.
+			 */
+			for (ref_fwnode = acpi_fwnode_handle(device);
+			     element < end && element->type == ACPI_TYPE_STRING;
+			     element++) {
+				ref_fwnode = acpi_fwnode_get_named_child_node(
+					ref_fwnode, element->string.pointer);
+				if (!ref_fwnode)
+					return -EINVAL;
+			}
+
 			/* assume following integer elements are all args */
 			for (i = 0; element + i < end && i < num_args; i++) {
 				int type = element[i].type;
@@ -657,7 +689,7 @@ int __acpi_node_get_property_reference(const struct fwnode_handle *fwnode,
 				return -EINVAL;
 
 			if (idx == index) {
-				args->fwnode = acpi_fwnode_handle(device);
+				args->fwnode = ref_fwnode;
 				args->nargs = nargs;
 				for (i = 0; i < nargs; i++)
 					args->args[i] = element[i].integer.value;
@@ -1190,23 +1222,6 @@ acpi_fwnode_property_read_string_array(const struct fwnode_handle *fwnode,
 				   val, nval);
 }
 
-static struct fwnode_handle *
-acpi_fwnode_get_named_child_node(const struct fwnode_handle *fwnode,
-				 const char *childname)
-{
-	struct fwnode_handle *child;
-
-	/*
-	 * Find first matching named child node of this fwnode.
-	 * For ACPI this will be a data only sub-node.
-	 */
-	fwnode_for_each_child_node(fwnode, child)
-		if (acpi_data_node_match(child, childname))
-			return child;
-
-	return NULL;
-}
-
 static int
 acpi_fwnode_get_reference_args(const struct fwnode_handle *fwnode,
 			       const char *prop, const char *nargs_prop,