1 files changed, 82 insertions, 20 deletions

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index 6979a3f9f90a..07d76fb740b6 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -2,14 +2,17 @@
 /*
  * ACPI device specific properties support.
  *
- * Copyright (C) 2014, Intel Corporation
+ * Copyright (C) 2014 - 2023, Intel Corporation
  * All rights reserved.
  *
  * Authors: Mika Westerberg <mika.westerberg@linux.intel.com>
  *          Darren Hart <dvhart@linux.intel.com>
  *          Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+ *          Sakari Ailus <sakari.ailus@linux.intel.com>
  */
 
+#define pr_fmt(fmt) "ACPI: " fmt
+
 #include <linux/acpi.h>
 #include <linux/device.h>
 #include <linux/export.h>
@@ -801,27 +804,15 @@ static int acpi_get_ref_args(struct fwnode_reference_args *args,
 	u32 nargs = 0, i;
 
 	/*
-	 * Find the referred data extension node under the
-	 * referred device node.
-	 */
-	for (; *element < end && (*element)->type == ACPI_TYPE_STRING;
-	     (*element)++) {
-		const char *child_name = (*element)->string.pointer;
-
-		ref_fwnode = acpi_fwnode_get_named_child_node(ref_fwnode, child_name);
-		if (!ref_fwnode)
-			return -EINVAL;
-	}
-
-	/*
 	 * Assume the following integer elements are all args. Stop counting on
-	 * the first reference or end of the package arguments. In case of
-	 * neither reference, nor integer, return an error, we can't parse it.
+	 * the first reference (possibly represented as a string) or end of the
+	 * package arguments. In case of neither reference, nor integer, return
+	 * an error, we can't parse it.
 	 */
 	for (i = 0; (*element) + i < end && i < num_args; i++) {
 		acpi_object_type type = (*element)[i].type;
 
-		if (type == ACPI_TYPE_LOCAL_REFERENCE)
+		if (type == ACPI_TYPE_LOCAL_REFERENCE || type == ACPI_TYPE_STRING)
 			break;
 
 		if (type == ACPI_TYPE_INTEGER)
@@ -845,6 +836,44 @@ static int acpi_get_ref_args(struct fwnode_reference_args *args,
 	return 0;
 }
 
+static struct fwnode_handle *acpi_parse_string_ref(const struct fwnode_handle *fwnode,
+						   const char *refstring)
+{
+	acpi_handle scope, handle;
+	struct acpi_data_node *dn;
+	struct acpi_device *device;
+	acpi_status status;
+
+	if (is_acpi_device_node(fwnode)) {
+		scope = to_acpi_device_node(fwnode)->handle;
+	} else if (is_acpi_data_node(fwnode)) {
+		scope = to_acpi_data_node(fwnode)->handle;
+	} else {
+		pr_debug("Bad node type for node %pfw\n", fwnode);
+		return NULL;
+	}
+
+	status = acpi_get_handle(scope, refstring, &handle);
+	if (ACPI_FAILURE(status)) {
+		acpi_handle_debug(scope, "Unable to get an ACPI handle for %s\n",
+				  refstring);
+		return NULL;
+	}
+
+	device = acpi_fetch_acpi_dev(handle);
+	if (device)
+		return acpi_fwnode_handle(device);
+
+	status = acpi_get_data_full(handle, acpi_nondev_subnode_tag,
+				    (void **)&dn, NULL);
+	if (ACPI_FAILURE(status) || !dn) {
+		acpi_handle_debug(handle, "Subnode not found\n");
+		return NULL;
+	}
+
+	return &dn->fwnode;
+}
+
 /**
  * __acpi_node_get_property_reference - returns handle to the referenced object
  * @fwnode: Firmware node to get the property from
@@ -887,6 +916,7 @@ int __acpi_node_get_property_reference(const struct fwnode_handle *fwnode,
 	const union acpi_object *element, *end;
 	const union acpi_object *obj;
 	const struct acpi_device_data *data;
+	struct fwnode_handle *ref_fwnode;
 	struct acpi_device *device;
 	int ret, idx = 0;
 
@@ -910,16 +940,30 @@ int __acpi_node_get_property_reference(const struct fwnode_handle *fwnode,
 
 		args->fwnode = acpi_fwnode_handle(device);
 		args->nargs = 0;
+
+		return 0;
+	case ACPI_TYPE_STRING:
+		if (index)
+			return -ENOENT;
+
+		ref_fwnode = acpi_parse_string_ref(fwnode, obj->string.pointer);
+		if (!ref_fwnode)
+			return -EINVAL;
+
+		args->fwnode = ref_fwnode;
+		args->nargs = 0;
+
 		return 0;
 	case ACPI_TYPE_PACKAGE:
 		/*
 		 * If it is not a single reference, then it is a package of
-		 * references followed by number of ints as follows:
+		 * references, followed by number of ints as follows:
 		 *
 		 *  Package () { REF, INT, REF, INT, INT }
 		 *
-		 * The index argument is then used to determine which reference
-		 * the caller wants (along with the arguments).
+		 * Here, REF may be either a local reference or a string. The
+		 * index argument is then used to determine which reference the
+		 * caller wants (along with the arguments).
 		 */
 		break;
 	default:
@@ -951,6 +995,24 @@ int __acpi_node_get_property_reference(const struct fwnode_handle *fwnode,
 				return 0;
 
 			break;
+		case ACPI_TYPE_STRING:
+			ref_fwnode = acpi_parse_string_ref(fwnode,
+							   element->string.pointer);
+			if (!ref_fwnode)
+				return -EINVAL;
+
+			element++;
+
+			ret = acpi_get_ref_args(idx == index ? args : NULL,
+						ref_fwnode, &element, end,
+						num_args);
+			if (ret < 0)
+				return ret;
+
+			if (idx == index)
+				return 0;
+
+			break;
 		case ACPI_TYPE_INTEGER:
 			if (idx == index)
 				return -ENOENT;