Merge tag 'devprop-4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull generic device properties framework updates from Rafael Wysocki:
 "These add support for the ports and endpoints concepts, based on the
  existing DT support for them, to the generic device properties
  framework and update the ACPI _DSD properties code to recognize ports
  and endpoints accordingly.

  Specifics:

   - Extend the ACPI _DSD properties code and the generic device
     properties framework to support the concept of remote endponts
     (Mika Westerberg, Sakari Ailus).

   - Document the support for ports and endpoints in _DSD properties and
     extend the generic device properties framework to make it more
     suitable for the handling of ports and endpoints (Sakari Ailus)"

* tag 'devprop-4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  device property: Read strings using string array reading functions
  device property: fwnode_property_read_string_array() returns nr of strings
  device property: Fix reading pset strings using array access functions
  device property: fwnode_property_read_string_array() may return -EILSEQ
  ACPI / DSD: Document references, ports and endpoints
  device property: Add fwnode_get_next_parent()
  device property: Add support for fwnode endpoints
  device property: Make dev_fwnode() public
  of: Add of_fwnode_handle() to convert device nodes to fwnode_handle
  device property: Add fwnode_handle_get()
  device property: Add support for remote endpoints
  ACPI / property: Add support for remote endpoints
  device property: Add fwnode_get_named_child_node()
  ACPI / property: Add fwnode_get_next_child_node()
  device property: Add fwnode_get_parent()
  ACPI / property: Add possiblity to retrieve parent firmware node

8 files changed, 761 insertions, 105 deletions

diff --git a/Documentation/acpi/dsd/graph.txt b/Documentation/acpi/dsd/graph.txt
new file mode 100644
index 000000000000..ac09e3138b79
--- /dev/null
+++ b/Documentation/acpi/dsd/graph.txt
@@ -0,0 +1,162 @@
+Graphs
+
+
+_DSD
+----
+
+_DSD (Device Specific Data) [7] is a predefined ACPI device
+configuration object that can be used to convey information on
+hardware features which are not specifically covered by the ACPI
+specification [1][6]. There are two _DSD extensions that are relevant
+for graphs: property [4] and hierarchical data extensions [5]. The
+property extension provides generic key-value pairs whereas the
+hierarchical data extension supports nodes with references to other
+nodes, forming a tree. The nodes in the tree may contain properties as
+defined by the property extension. The two extensions together provide
+a tree-like structure with zero or more properties (key-value pairs)
+in each node of the tree.
+
+The data structure may be accessed at runtime by using the device_*
+and fwnode_* functions defined in include/linux/fwnode.h .
+
+Fwnode represents a generic firmware node object. It is independent on
+the firmware type. In ACPI, fwnodes are _DSD hierarchical data
+extensions objects. A device's _DSD object is represented by an
+fwnode.
+
+The data structure may be referenced to elsewhere in the ACPI tables
+by using a hard reference to the device itself and an index to the
+hierarchical data extension array on each depth.
+
+
+Ports and endpoints
+-------------------
+
+The port and endpoint concepts are very similar to those in Devicetree
+[3]. A port represents an interface in a device, and an endpoint
+represents a connection to that interface.
+
+All port nodes are located under the device's "_DSD" node in the
+hierarchical data extension tree. The property extension related to
+each port node must contain the key "port" and an integer value which
+is the number of the port. The object it refers to should be called "PRTX",
+where "X" is the number of the port.
+
+Further on, endpoints are located under the individual port nodes. The
+first hierarchical data extension package list entry of the endpoint
+nodes must begin with "endpoint" and must be followed by the number
+of the endpoint. The object it refers to should be called "EPXY", where
+"X" is the number of the port and "Y" is the number of the endpoint.
+
+Each port node contains a property extension key "port", the value of
+which is the number of the port node. The each endpoint is similarly numbered
+with a property extension key "endpoint". Port numbers must be unique within a
+device and endpoint numbers must be unique within a port.
+
+The endpoint reference uses property extension with "remote-endpoint" property
+name followed by a reference in the same package. Such references consist of the
+the remote device reference, number of the port in the device and finally the
+number of the endpoint in that port. Individual references thus appear as:
+
+    Package() { device, port_number, endpoint_number }
+
+The references to endpoints must be always done both ways, to the
+remote endpoint and back from the referred remote endpoint node.
+
+A simple example of this is show below:
+
+    Scope (\_SB.PCI0.I2C2)
+    {
+	Device (CAM0)
+	{
+	    Name (_DSD, Package () {
+		ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+		Package () {
+		    Package () { "compatible", Package () { "nokia,smia" } },
+		},
+		ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
+		Package () {
+		    Package () { "port0", "PRT0" },
+		}
+	    })
+	    Name (PRT0, Package() {
+		ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+		Package () {
+		    Package () { "port", 0 },
+		},
+		ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
+		Package () {
+		    Package () { "endpoint0", "EP00" },
+		}
+	    })
+	    Name (EP00, Package() {
+		ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+		Package () {
+		    Package () { "endpoint", 0 },
+		    Package () { "remote-endpoint", Package() { \_SB.PCI0.ISP, 4, 0 } },
+		}
+	    })
+	}
+    }
+
+    Scope (\_SB.PCI0)
+    {
+	Device (ISP)
+	{
+	    Name (_DSD, Package () {
+		ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
+		Package () {
+		    Package () { "port4", "PRT4" },
+		}
+	    })
+
+	    Name (PRT4, Package() {
+		ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+		Package () {
+		    Package () { "port", 4 }, /* CSI-2 port number */
+		},
+		ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
+		Package () {
+		    Package () { "endpoint0", "EP40" },
+		}
+	    })
+
+	    Name (EP40, Package() {
+		ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+		Package () {
+		    Package () { "endpoint", 0 },
+		    Package () { "remote-endpoint", Package () { \_SB.PCI0.I2C2.CAM0, 0, 0 } },
+		}
+	    })
+	}
+    }
+
+Here, the port 0 of the "CAM0" device is connected to the port 4 of
+the "ISP" device and vice versa.
+
+
+References
+----------
+
+[1] _DSD (Device Specific Data) Implementation Guide.
+    <URL:http://www.uefi.org/sites/default/files/resources/_DSD-implementation-guide-toplevel-1_1.htm>,
+    referenced 2016-10-03.
+
+[2] Devicetree. <URL:http://www.devicetree.org>, referenced 2016-10-03.
+
+[3] Documentation/devicetree/bindings/graph.txt
+
+[4] Device Properties UUID For _DSD.
+    <URL:http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf>,
+    referenced 2016-10-04.
+
+[5] Hierarchical Data Extension UUID For _DSD.
+    <URL:http://www.uefi.org/sites/default/files/resources/_DSD-hierarchical-data-extension-UUID-v1.pdf>,
+    referenced 2016-10-04.
+
+[6] Advanced Configuration and Power Interface Specification.
+    <URL:http://www.uefi.org/sites/default/files/resources/ACPI_6_1.pdf>,
+    referenced 2016-10-04.
+
+[7] _DSD Device Properties Usage Rules.
+    Documentation/acpi/DSD-properties-rules.txt
diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index 3afddcd834ef..9364398204e9 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -37,14 +37,16 @@ static const u8 ads_uuid[16] = {
 
 static bool acpi_enumerate_nondev_subnodes(acpi_handle scope,
 					   const union acpi_object *desc,
-					   struct acpi_device_data *data);
+					   struct acpi_device_data *data,
+					   struct fwnode_handle *parent);
 static bool acpi_extract_properties(const union acpi_object *desc,
 				    struct acpi_device_data *data);
 
 static bool acpi_nondev_subnode_extract(const union acpi_object *desc,
 					acpi_handle handle,
 					const union acpi_object *link,
-					struct list_head *list)
+					struct list_head *list,
+					struct fwnode_handle *parent)
 {
 	struct acpi_data_node *dn;
 	bool result;
@@ -55,6 +57,7 @@ static bool acpi_nondev_subnode_extract(const union acpi_object *desc,
 
 	dn->name = link->package.elements[0].string.pointer;
 	dn->fwnode.type = FWNODE_ACPI_DATA;
+	dn->parent = parent;
 	INIT_LIST_HEAD(&dn->data.subnodes);
 
 	result = acpi_extract_properties(desc, &dn->data);
@@ -71,9 +74,11 @@ static bool acpi_nondev_subnode_extract(const union acpi_object *desc,
 		 */
 		status = acpi_get_parent(handle, &scope);
 		if (ACPI_SUCCESS(status)
-		    && acpi_enumerate_nondev_subnodes(scope, desc, &dn->data))
+		    && acpi_enumerate_nondev_subnodes(scope, desc, &dn->data,
+						      &dn->fwnode))
 			result = true;
-	} else if (acpi_enumerate_nondev_subnodes(NULL, desc, &dn->data)) {
+	} else if (acpi_enumerate_nondev_subnodes(NULL, desc, &dn->data,
+						  &dn->fwnode)) {
 		result = true;
 	}
 
@@ -91,7 +96,8 @@ static bool acpi_nondev_subnode_extract(const union acpi_object *desc,
 
 static bool acpi_nondev_subnode_data_ok(acpi_handle handle,
 					const union acpi_object *link,
-					struct list_head *list)
+					struct list_head *list,
+					struct fwnode_handle *parent)
 {
 	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
 	acpi_status status;
@@ -101,7 +107,8 @@ static bool acpi_nondev_subnode_data_ok(acpi_handle handle,
 	if (ACPI_FAILURE(status))
 		return false;
 
-	if (acpi_nondev_subnode_extract(buf.pointer, handle, link, list))
+	if (acpi_nondev_subnode_extract(buf.pointer, handle, link, list,
+					parent))
 		return true;
 
 	ACPI_FREE(buf.pointer);
@@ -110,7 +117,8 @@ static bool acpi_nondev_subnode_data_ok(acpi_handle handle,
 
 static bool acpi_nondev_subnode_ok(acpi_handle scope,
 				   const union acpi_object *link,
-				   struct list_head *list)
+				   struct list_head *list,
+				   struct fwnode_handle *parent)
 {
 	acpi_handle handle;
 	acpi_status status;
@@ -123,12 +131,13 @@ static bool acpi_nondev_subnode_ok(acpi_handle scope,
 	if (ACPI_FAILURE(status))
 		return false;
 
-	return acpi_nondev_subnode_data_ok(handle, link, list);
+	return acpi_nondev_subnode_data_ok(handle, link, list, parent);
 }
 
 static int acpi_add_nondev_subnodes(acpi_handle scope,
 				    const union acpi_object *links,
-				    struct list_head *list)
+				    struct list_head *list,
+				    struct fwnode_handle *parent)
 {
 	bool ret = false;
 	int i;
@@ -150,15 +159,18 @@ static int acpi_add_nondev_subnodes(acpi_handle scope,
 		/* The second one may be a string, a reference or a package. */
 		switch (link->package.elements[1].type) {
 		case ACPI_TYPE_STRING:
-			result = acpi_nondev_subnode_ok(scope, link, list);
+			result = acpi_nondev_subnode_ok(scope, link, list,
+							 parent);
 			break;
 		case ACPI_TYPE_LOCAL_REFERENCE:
 			handle = link->package.elements[1].reference.handle;
-			result = acpi_nondev_subnode_data_ok(handle, link, list);
+			result = acpi_nondev_subnode_data_ok(handle, link, list,
+							     parent);
 			break;
 		case ACPI_TYPE_PACKAGE:
 			desc = &link->package.elements[1];
-			result = acpi_nondev_subnode_extract(desc, NULL, link, list);
+			result = acpi_nondev_subnode_extract(desc, NULL, link,
+							     list, parent);
 			break;
 		default:
 			result = false;
@@ -172,7 +184,8 @@ static int acpi_add_nondev_subnodes(acpi_handle scope,
 
 static bool acpi_enumerate_nondev_subnodes(acpi_handle scope,
 					   const union acpi_object *desc,
-					   struct acpi_device_data *data)
+					   struct acpi_device_data *data,
+					   struct fwnode_handle *parent)
 {
 	int i;
 
@@ -194,7 +207,8 @@ static bool acpi_enumerate_nondev_subnodes(acpi_handle scope,
 		if (memcmp(uuid->buffer.pointer, ads_uuid, sizeof(ads_uuid)))
 			continue;
 
-		return acpi_add_nondev_subnodes(scope, links, &data->subnodes);
+		return acpi_add_nondev_subnodes(scope, links, &data->subnodes,
+						parent);
 	}
 
 	return false;
@@ -345,7 +359,8 @@ void acpi_init_properties(struct acpi_device *adev)
 		if (acpi_of)
 			acpi_init_of_compatible(adev);
 	}
-	if (acpi_enumerate_nondev_subnodes(adev->handle, buf.pointer, &adev->data))
+	if (acpi_enumerate_nondev_subnodes(adev->handle, buf.pointer,
+					&adev->data, acpi_fwnode_handle(adev)))
 		adev->data.pointer = buf.pointer;
 
 	if (!adev->data.pointer) {
@@ -699,6 +714,8 @@ static int acpi_data_prop_read_single(struct acpi_device_data *data,
 			return ret;
 
 		*(char **)val = obj->string.pointer;
+
+		return 1;
 	} else {
 		ret = -EINVAL;
 	}
@@ -708,7 +725,15 @@ static int acpi_data_prop_read_single(struct acpi_device_data *data,
 int acpi_dev_prop_read_single(struct acpi_device *adev, const char *propname,
 			      enum dev_prop_type proptype, void *val)
 {
-	return adev ? acpi_data_prop_read_single(&adev->data, propname, proptype, val) : -EINVAL;
+	int ret;
+
+	if (!adev)
+		return -EINVAL;
+
+	ret = acpi_data_prop_read_single(&adev->data, propname, proptype, val);
+	if (ret < 0 || proptype != ACPI_TYPE_STRING)
+		return ret;
+	return 0;
 }
 
 static int acpi_copy_property_array_u8(const union acpi_object *items, u8 *val,
@@ -784,7 +809,7 @@ static int acpi_copy_property_array_string(const union acpi_object *items,
 
 		val[i] = items[i].string.pointer;
 	}
-	return 0;
+	return nval;
 }
 
 static int acpi_data_prop_read(struct acpi_device_data *data,
@@ -798,7 +823,7 @@ static int acpi_data_prop_read(struct acpi_device_data *data,
 
 	if (val && nval == 1) {
 		ret = acpi_data_prop_read_single(data, propname, proptype, val);
-		if (!ret)
+		if (ret >= 0)
 			return ret;
 	}
 
@@ -809,7 +834,7 @@ static int acpi_data_prop_read(struct acpi_device_data *data,
 	if (!val)
 		return obj->package.count;
 
-	if (nval > obj->package.count)
+	if (proptype != DEV_PROP_STRING && nval > obj->package.count)
 		return -EOVERFLOW;
 	else if (nval <= 0)
 		return -EINVAL;
@@ -830,7 +855,9 @@ static int acpi_data_prop_read(struct acpi_device_data *data,
 		ret = acpi_copy_property_array_u64(items, (u64 *)val, nval);
 		break;
 	case DEV_PROP_STRING:
-		ret = acpi_copy_property_array_string(items, (char **)val, nval);
+		ret = acpi_copy_property_array_string(
+			items, (char **)val,
+			min_t(u32, nval, obj->package.count));
 		break;
 	default:
 		ret = -EINVAL;
@@ -865,21 +892,22 @@ int acpi_node_prop_read(struct fwnode_handle *fwnode,  const char *propname,
 }
 
 /**
- * acpi_get_next_subnode - Return the next child node handle for a device.
- * @dev: Device to find the next child node for.
+ * acpi_get_next_subnode - Return the next child node handle for a fwnode
+ * @fwnode: Firmware node to find the next child node for.
  * @child: Handle to one of the device's child nodes or a null handle.
  */
-struct fwnode_handle *acpi_get_next_subnode(struct device *dev,
+struct fwnode_handle *acpi_get_next_subnode(struct fwnode_handle *fwnode,
 					    struct fwnode_handle *child)
 {
-	struct acpi_device *adev = ACPI_COMPANION(dev);
+	struct acpi_device *adev = to_acpi_device_node(fwnode);
 	struct list_head *head, *next;
 
-	if (!adev)
-		return NULL;
-
 	if (!child || child->type == FWNODE_ACPI) {
-		head = &adev->children;
+		if (adev)
+			head = &adev->children;
+		else
+			goto nondev;
+
 		if (list_empty(head))
 			goto nondev;
 
@@ -888,7 +916,6 @@ struct fwnode_handle *acpi_get_next_subnode(struct device *dev,
 			next = adev->node.next;
 			if (next == head) {
 				child = NULL;
-				adev = ACPI_COMPANION(dev);
 				goto nondev;
 			}
 			adev = list_entry(next, struct acpi_device, node);
@@ -900,9 +927,16 @@ struct fwnode_handle *acpi_get_next_subnode(struct device *dev,
 
  nondev:
 	if (!child || child->type == FWNODE_ACPI_DATA) {
+		struct acpi_data_node *data = to_acpi_data_node(fwnode);
 		struct acpi_data_node *dn;
 
-		head = &adev->data.subnodes;
+		if (adev)
+			head = &adev->data.subnodes;
+		else if (data)
+			head = &data->data.subnodes;
+		else
+			return NULL;
+
 		if (list_empty(head))
 			return NULL;
 
@@ -920,3 +954,168 @@ struct fwnode_handle *acpi_get_next_subnode(struct device *dev,
 	}
 	return NULL;
 }
+
+/**
+ * acpi_node_get_parent - Return parent fwnode of this fwnode
+ * @fwnode: Firmware node whose parent to get
+ *
+ * Returns parent node of an ACPI device or data firmware node or %NULL if
+ * not available.
+ */
+struct fwnode_handle *acpi_node_get_parent(struct fwnode_handle *fwnode)
+{
+	if (is_acpi_data_node(fwnode)) {
+		/* All data nodes have parent pointer so just return that */
+		return to_acpi_data_node(fwnode)->parent;
+	} else if (is_acpi_device_node(fwnode)) {
+		acpi_handle handle, parent_handle;
+
+		handle = to_acpi_device_node(fwnode)->handle;
+		if (ACPI_SUCCESS(acpi_get_parent(handle, &parent_handle))) {
+			struct acpi_device *adev;
+
+			if (!acpi_bus_get_device(parent_handle, &adev))
+				return acpi_fwnode_handle(adev);
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * acpi_graph_get_next_endpoint - Get next endpoint ACPI firmware node
+ * @fwnode: Pointer to the parent firmware node
+ * @prev: Previous endpoint node or %NULL to get the first
+ *
+ * Looks up next endpoint ACPI firmware node below a given @fwnode. Returns
+ * %NULL if there is no next endpoint, ERR_PTR() in case of error. In case
+ * of success the next endpoint is returned.
+ */
+struct fwnode_handle *acpi_graph_get_next_endpoint(struct fwnode_handle *fwnode,
+						   struct fwnode_handle *prev)
+{
+	struct fwnode_handle *port = NULL;
+	struct fwnode_handle *endpoint;
+
+	if (!prev) {
+		do {
+			port = fwnode_get_next_child_node(fwnode, port);
+			/* Ports must have port property */
+			if (fwnode_property_present(port, "port"))
+				break;
+		} while (port);
+	} else {
+		port = fwnode_get_parent(prev);
+	}
+
+	if (!port)
+		return NULL;
+
+	endpoint = fwnode_get_next_child_node(port, prev);
+	while (!endpoint) {
+		port = fwnode_get_next_child_node(fwnode, port);
+		if (!port)
+			break;
+		if (fwnode_property_present(port, "port"))
+			endpoint = fwnode_get_next_child_node(port, NULL);
+	}
+
+	if (endpoint) {
+		/* Endpoints must have "endpoint" property */
+		if (!fwnode_property_present(endpoint, "endpoint"))
+			return ERR_PTR(-EPROTO);
+	}
+
+	return endpoint;
+}
+
+/**
+ * acpi_graph_get_child_prop_value - Return a child with a given property value
+ * @fwnode: device fwnode
+ * @prop_name: The name of the property to look for
+ * @val: the desired property value
+ *
+ * Return the port node corresponding to a given port number. Returns
+ * the child node on success, NULL otherwise.
+ */
+static struct fwnode_handle *acpi_graph_get_child_prop_value(
+	struct fwnode_handle *fwnode, const char *prop_name, unsigned int val)
+{
+	struct fwnode_handle *child;
+
+	fwnode_for_each_child_node(fwnode, child) {
+		u32 nr;
+
+		if (!fwnode_property_read_u32(fwnode, prop_name, &nr))
+			continue;
+
+		if (val == nr)
+			return child;
+	}
+
+	return NULL;
+}
+
+
+/**
+ * acpi_graph_get_remote_enpoint - Parses and returns remote end of an endpoint
+ * @fwnode: Endpoint firmware node pointing to a remote device
+ * @parent: Firmware node of remote port parent is filled here if not %NULL
+ * @port: Firmware node of remote port is filled here if not %NULL
+ * @endpoint: Firmware node of remote endpoint is filled here if not %NULL
+ *
+ * Function parses remote end of ACPI firmware remote endpoint and fills in
+ * fields requested by the caller. Returns %0 in case of success and
+ * negative errno otherwise.
+ */
+int acpi_graph_get_remote_endpoint(struct fwnode_handle *fwnode,
+				   struct fwnode_handle **parent,
+				   struct fwnode_handle **port,
+				   struct fwnode_handle **endpoint)
+{
+	unsigned int port_nr, endpoint_nr;
+	struct acpi_reference_args args;
+	int ret;
+
+	memset(&args, 0, sizeof(args));
+	ret = acpi_node_get_property_reference(fwnode, "remote-endpoint", 0,
+					       &args);
+	if (ret)
+		return ret;
+
+	/*
+	 * Always require two arguments with the reference: port and
+	 * endpoint indices.
+	 */
+	if (args.nargs != 2)
+		return -EPROTO;
+
+	fwnode = acpi_fwnode_handle(args.adev);
+	port_nr = args.args[0];
+	endpoint_nr = args.args[1];
+
+	if (parent)
+		*parent = fwnode;
+
+	if (!port && !endpoint)
+		return 0;
+
+	fwnode = acpi_graph_get_child_prop_value(fwnode, "port", port_nr);
+	if (!fwnode)
+		return -EPROTO;
+
+	if (port)
+		*port = fwnode;
+
+	if (!endpoint)
+		return 0;
+
+	fwnode = acpi_graph_get_child_prop_value(fwnode, "endpoint",
+						 endpoint_nr);
+	if (!fwnode)
+		return -EPROTO;
+
+	*endpoint = fwnode;
+
+	return 0;
+}
diff --git a/drivers/base/property.c b/drivers/base/property.c
index c458c63e353f..149de311a10e 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -15,6 +15,7 @@
 #include <linux/kernel.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/of_graph.h>
 #include <linux/property.h>
 #include <linux/etherdevice.h>
 #include <linux/phy.h>
@@ -146,47 +147,45 @@ static int pset_prop_read_string_array(struct property_set *pset,
 				       const char *propname,
 				       const char **strings, size_t nval)
 {
+	const struct property_entry *prop;
 	const void *pointer;
-	size_t length = nval * sizeof(*strings);
+	size_t array_len, length;
+
+	/* Find out the array length. */
+	prop = pset_prop_get(pset, propname);
+	if (!prop)
+		return -EINVAL;
+
+	if (!prop->is_array)
+		/* The array length for a non-array string property is 1. */
+		array_len = 1;
+	else
+		/* Find the length of an array. */
+		array_len = pset_prop_count_elems_of_size(pset, propname,
+							  sizeof(const char *));
+
+	/* Return how many there are if strings is NULL. */
+	if (!strings)
+		return array_len;
+
+	array_len = min(nval, array_len);
+	length = array_len * sizeof(*strings);
 
 	pointer = pset_prop_find(pset, propname, length);
 	if (IS_ERR(pointer))
 		return PTR_ERR(pointer);
 
 	memcpy(strings, pointer, length);
-	return 0;
-}
 
-static int pset_prop_read_string(struct property_set *pset,
-				 const char *propname, const char **strings)
-{
-	const struct property_entry *prop;
-	const char * const *pointer;
-
-	prop = pset_prop_get(pset, propname);
-	if (!prop)
-		return -EINVAL;
-	if (!prop->is_string)
-		return -EILSEQ;
-	if (prop->is_array) {
-		pointer = prop->pointer.str;
-		if (!pointer)
-			return -ENODATA;
-	} else {
-		pointer = &prop->value.str;
-		if (*pointer && strnlen(*pointer, prop->length) >= prop->length)
-			return -EILSEQ;
-	}
-
-	*strings = *pointer;
-	return 0;
+	return array_len;
 }
 
-static inline struct fwnode_handle *dev_fwnode(struct device *dev)
+struct fwnode_handle *dev_fwnode(struct device *dev)
 {
 	return IS_ENABLED(CONFIG_OF) && dev->of_node ?
 		&dev->of_node->fwnode : dev->fwnode;
 }
+EXPORT_SYMBOL_GPL(dev_fwnode);
 
 /**
  * device_property_present - check if a property of a device is present
@@ -340,8 +339,8 @@ EXPORT_SYMBOL_GPL(device_property_read_u64_array);
  * Function reads an array of string properties with @propname from the device
  * firmware description and stores them to @val if found.
  *
- * Return: number of values if @val was %NULL,
- *         %0 if the property was found (success),
+ * Return: number of values read on success if @val is non-NULL,
+ *	   number of values available on success if @val is NULL,
  *	   %-EINVAL if given arguments are not valid,
  *	   %-ENODATA if the property does not have a value,
  *	   %-EPROTO or %-EILSEQ if the property is not an array of strings,
@@ -553,25 +552,8 @@ static int __fwnode_property_read_string_array(struct fwnode_handle *fwnode,
 		return acpi_node_prop_read(fwnode, propname, DEV_PROP_STRING,
 					   val, nval);
 	else if (is_pset_node(fwnode))
-		return val ?
-			pset_prop_read_string_array(to_pset_node(fwnode),
-						    propname, val, nval) :
-			pset_prop_count_elems_of_size(to_pset_node(fwnode),
-						      propname,
-						      sizeof(const char *));
-	return -ENXIO;
-}
-
-static int __fwnode_property_read_string(struct fwnode_handle *fwnode,
-					 const char *propname, const char **val)
-{
-	if (is_of_node(fwnode))
-		return of_property_read_string(to_of_node(fwnode), propname, val);
-	else if (is_acpi_node(fwnode))
-		return acpi_node_prop_read(fwnode, propname, DEV_PROP_STRING,
-					   val, 1);
-	else if (is_pset_node(fwnode))
-		return pset_prop_read_string(to_pset_node(fwnode), propname, val);
+		return pset_prop_read_string_array(to_pset_node(fwnode),
+						   propname, val, nval);
 	return -ENXIO;
 }
 
@@ -585,11 +567,11 @@ static int __fwnode_property_read_string(struct fwnode_handle *fwnode,
  * Read an string list property @propname from the given firmware node and store
  * them to @val if found.
  *
- * Return: number of values if @val was %NULL,
- *         %0 if the property was found (success),
+ * Return: number of values read on success if @val is non-NULL,
+ *	   number of values available on success if @val is NULL,
  *	   %-EINVAL if given arguments are not valid,
  *	   %-ENODATA if the property does not have a value,
- *	   %-EPROTO if the property is not an array of strings,
+ *	   %-EPROTO or %-EILSEQ if the property is not an array of strings,
  *	   %-EOVERFLOW if the size of the property is not as expected,
  *	   %-ENXIO if no suitable firmware interface is present.
  */
@@ -626,14 +608,9 @@ EXPORT_SYMBOL_GPL(fwnode_property_read_string_array);
 int fwnode_property_read_string(struct fwnode_handle *fwnode,
 				const char *propname, const char **val)
 {
-	int ret;
+	int ret = fwnode_property_read_string_array(fwnode, propname, val, 1);
 
-	ret = __fwnode_property_read_string(fwnode, propname, val);
-	if (ret == -EINVAL && !IS_ERR_OR_NULL(fwnode) &&
-	    !IS_ERR_OR_NULL(fwnode->secondary))
-		ret = __fwnode_property_read_string(fwnode->secondary,
-						    propname, val);
-	return ret;
+	return ret < 0 ? ret : 0;
 }
 EXPORT_SYMBOL_GPL(fwnode_property_read_string);
 
@@ -932,41 +909,109 @@ int device_add_properties(struct device *dev,
 EXPORT_SYMBOL_GPL(device_add_properties);
 
 /**
- * device_get_next_child_node - Return the next child node handle for a device
- * @dev: Device to find the next child node for.
- * @child: Handle to one of the device's child nodes or a null handle.
+ * fwnode_get_next_parent - Iterate to the node's parent
+ * @fwnode: Firmware whose parent is retrieved
+ *
+ * This is like fwnode_get_parent() except that it drops the refcount
+ * on the passed node, making it suitable for iterating through a
+ * node's parents.
+ *
+ * Returns a node pointer with refcount incremented, use
+ * fwnode_handle_node() on it when done.
  */
-struct fwnode_handle *device_get_next_child_node(struct device *dev,
+struct fwnode_handle *fwnode_get_next_parent(struct fwnode_handle *fwnode)
+{
+	struct fwnode_handle *parent = fwnode_get_parent(fwnode);
+
+	fwnode_handle_put(fwnode);
+
+	return parent;
+}
+EXPORT_SYMBOL_GPL(fwnode_get_next_parent);
+
+/**
+ * fwnode_get_parent - Return parent firwmare node
+ * @fwnode: Firmware whose parent is retrieved
+ *
+ * Return parent firmware node of the given node if possible or %NULL if no
+ * parent was available.
+ */
+struct fwnode_handle *fwnode_get_parent(struct fwnode_handle *fwnode)
+{
+	struct fwnode_handle *parent = NULL;
+
+	if (is_of_node(fwnode)) {
+		struct device_node *node;
+
+		node = of_get_parent(to_of_node(fwnode));
+		if (node)
+			parent = &node->fwnode;
+	} else if (is_acpi_node(fwnode)) {
+		parent = acpi_node_get_parent(fwnode);
+	}
+
+	return parent;
+}
+EXPORT_SYMBOL_GPL(fwnode_get_parent);
+
+/**
+ * fwnode_get_next_child_node - Return the next child node handle for a node
+ * @fwnode: Firmware node to find the next child node for.
+ * @child: Handle to one of the node's child nodes or a %NULL handle.
+ */
+struct fwnode_handle *fwnode_get_next_child_node(struct fwnode_handle *fwnode,
 						 struct fwnode_handle *child)
 {
-	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
+	if (is_of_node(fwnode)) {
 		struct device_node *node;
 
-		node = of_get_next_available_child(dev->of_node, to_of_node(child));
+		node = of_get_next_available_child(to_of_node(fwnode),
+						   to_of_node(child));
 		if (node)
 			return &node->fwnode;
-	} else if (IS_ENABLED(CONFIG_ACPI)) {
-		return acpi_get_next_subnode(dev, child);
+	} else if (is_acpi_node(fwnode)) {
+		return acpi_get_next_subnode(fwnode, child);
 	}
+
 	return NULL;
 }
+EXPORT_SYMBOL_GPL(fwnode_get_next_child_node);
+
+/**
+ * device_get_next_child_node - Return the next child node handle for a device
+ * @dev: Device to find the next child node for.
+ * @child: Handle to one of the device's child nodes or a null handle.
+ */
+struct fwnode_handle *device_get_next_child_node(struct device *dev,
+						 struct fwnode_handle *child)
+{
+	struct acpi_device *adev = ACPI_COMPANION(dev);
+	struct fwnode_handle *fwnode = NULL;
+
+	if (dev->of_node)
+		fwnode = &dev->of_node->fwnode;
+	else if (adev)
+		fwnode = acpi_fwnode_handle(adev);
+
+	return fwnode_get_next_child_node(fwnode, child);
+}
 EXPORT_SYMBOL_GPL(device_get_next_child_node);
 
 /**
- * device_get_named_child_node - Return first matching named child node handle
- * @dev: Device to find the named child node for.
+ * fwnode_get_named_child_node - Return first matching named child node handle
+ * @fwnode: Firmware node to find the named child node for.
  * @childname: String to match child node name against.
  */
-struct fwnode_handle *device_get_named_child_node(struct device *dev,
+struct fwnode_handle *fwnode_get_named_child_node(struct fwnode_handle *fwnode,
 						  const char *childname)
 {
 	struct fwnode_handle *child;
 
 	/*
-	 * Find first matching named child node of this device.
+	 * Find first matching named child node of this fwnode.
 	 * For ACPI this will be a data only sub-node.
 	 */
-	device_for_each_child_node(dev, child) {
+	fwnode_for_each_child_node(fwnode, child) {
 		if (is_of_node(child)) {
 			if (!of_node_cmp(to_of_node(child)->name, childname))
 				return child;
@@ -978,9 +1023,32 @@ struct fwnode_handle *device_get_named_child_node(struct device *dev,
 
 	return NULL;
 }
+EXPORT_SYMBOL_GPL(fwnode_get_named_child_node);
+
+/**
+ * device_get_named_child_node - Return first matching named child node handle
+ * @dev: Device to find the named child node for.
+ * @childname: String to match child node name against.
+ */
+struct fwnode_handle *device_get_named_child_node(struct device *dev,
+						  const char *childname)
+{
+	return fwnode_get_named_child_node(dev_fwnode(dev), childname);
+}
 EXPORT_SYMBOL_GPL(device_get_named_child_node);
 
 /**
+ * fwnode_handle_get - Obtain a reference to a device node
+ * @fwnode: Pointer to the device node to obtain the reference to.
+ */
+void fwnode_handle_get(struct fwnode_handle *fwnode)
+{
+	if (is_of_node(fwnode))
+		of_node_get(to_of_node(fwnode));
+}
+EXPORT_SYMBOL_GPL(fwnode_handle_get);
+
+/**
  * fwnode_handle_put - Drop reference to a device node
  * @fwnode: Pointer to the device node to drop the reference to.
  *
@@ -1117,3 +1185,157 @@ void *device_get_mac_address(struct device *dev, char *addr, int alen)
 	return device_get_mac_addr(dev, "address", addr, alen);
 }
 EXPORT_SYMBOL(device_get_mac_address);
+
+/**
+ * device_graph_get_next_endpoint - Get next endpoint firmware node
+ * @fwnode: Pointer to the parent firmware node
+ * @prev: Previous endpoint node or %NULL to get the first
+ *
+ * Returns an endpoint firmware node pointer or %NULL if no more endpoints
+ * are available.
+ */
+struct fwnode_handle *
+fwnode_graph_get_next_endpoint(struct fwnode_handle *fwnode,
+			       struct fwnode_handle *prev)
+{
+	struct fwnode_handle *endpoint = NULL;
+
+	if (is_of_node(fwnode)) {
+		struct device_node *node;
+
+		node = of_graph_get_next_endpoint(to_of_node(fwnode),
+						  to_of_node(prev));
+
+		if (node)
+			endpoint = &node->fwnode;
+	} else if (is_acpi_node(fwnode)) {
+		endpoint = acpi_graph_get_next_endpoint(fwnode, prev);
+		if (IS_ERR(endpoint))
+			endpoint = NULL;
+	}
+
+	return endpoint;
+
+}
+EXPORT_SYMBOL_GPL(fwnode_graph_get_next_endpoint);
+
+/**
+ * fwnode_graph_get_remote_port_parent - Return fwnode of a remote device
+ * @fwnode: Endpoint firmware node pointing to the remote endpoint
+ *
+ * Extracts firmware node of a remote device the @fwnode points to.
+ */
+struct fwnode_handle *
+fwnode_graph_get_remote_port_parent(struct fwnode_handle *fwnode)
+{
+	struct fwnode_handle *parent = NULL;
+
+	if (is_of_node(fwnode)) {
+		struct device_node *node;
+
+		node = of_graph_get_remote_port_parent(to_of_node(fwnode));
+		if (node)
+			parent = &node->fwnode;
+	} else if (is_acpi_node(fwnode)) {
+		int ret;
+
+		ret = acpi_graph_get_remote_endpoint(fwnode, &parent, NULL,
+						     NULL);
+		if (ret)
+			return NULL;
+	}
+
+	return parent;
+}
+EXPORT_SYMBOL_GPL(fwnode_graph_get_remote_port_parent);
+
+/**
+ * fwnode_graph_get_remote_port - Return fwnode of a remote port
+ * @fwnode: Endpoint firmware node pointing to the remote endpoint
+ *
+ * Extracts firmware node of a remote port the @fwnode points to.
+ */
+struct fwnode_handle *fwnode_graph_get_remote_port(struct fwnode_handle *fwnode)
+{
+	struct fwnode_handle *port = NULL;
+
+	if (is_of_node(fwnode)) {
+		struct device_node *node;
+
+		node = of_graph_get_remote_port(to_of_node(fwnode));
+		if (node)
+			port = &node->fwnode;
+	} else if (is_acpi_node(fwnode)) {
+		int ret;
+
+		ret = acpi_graph_get_remote_endpoint(fwnode, NULL, &port, NULL);
+		if (ret)
+			return NULL;
+	}
+
+	return port;
+}
+EXPORT_SYMBOL_GPL(fwnode_graph_get_remote_port);
+
+/**
+ * fwnode_graph_get_remote_endpoint - Return fwnode of a remote endpoint
+ * @fwnode: Endpoint firmware node pointing to the remote endpoint
+ *
+ * Extracts firmware node of a remote endpoint the @fwnode points to.
+ */
+struct fwnode_handle *
+fwnode_graph_get_remote_endpoint(struct fwnode_handle *fwnode)
+{
+	struct fwnode_handle *endpoint = NULL;
+
+	if (is_of_node(fwnode)) {
+		struct device_node *node;
+
+		node = of_parse_phandle(to_of_node(fwnode), "remote-endpoint",
+					0);
+		if (node)
+			endpoint = &node->fwnode;
+	} else if (is_acpi_node(fwnode)) {
+		int ret;
+
+		ret = acpi_graph_get_remote_endpoint(fwnode, NULL, NULL,
+						     &endpoint);
+		if (ret)
+			return NULL;
+	}
+
+	return endpoint;
+}
+EXPORT_SYMBOL_GPL(fwnode_graph_get_remote_endpoint);
+
+/**
+ * fwnode_graph_parse_endpoint - parse common endpoint node properties
+ * @fwnode: pointer to endpoint fwnode_handle
+ * @endpoint: pointer to the fwnode endpoint data structure
+ *
+ * Parse @fwnode representing a graph endpoint node and store the
+ * information in @endpoint. The caller must hold a reference to
+ * @fwnode.
+ */
+int fwnode_graph_parse_endpoint(struct fwnode_handle *fwnode,
+				struct fwnode_endpoint *endpoint)
+{
+	struct fwnode_handle *port_fwnode = fwnode_get_parent(fwnode);
+
+	memset(endpoint, 0, sizeof(*endpoint));
+
+	endpoint->local_fwnode = fwnode;
+
+	if (is_acpi_node(port_fwnode)) {
+		fwnode_property_read_u32(port_fwnode, "port", &endpoint->port);
+		fwnode_property_read_u32(fwnode, "endpoint", &endpoint->id);
+	} else {
+		fwnode_property_read_u32(port_fwnode, "reg", &endpoint->port);
+		fwnode_property_read_u32(fwnode, "reg", &endpoint->id);
+	}
+
+	fwnode_handle_put(port_fwnode);
+
+	return 0;
+}
+EXPORT_SYMBOL(fwnode_graph_parse_endpoint);
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index b53c058e7009..2fc678e08d8d 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -387,6 +387,7 @@ struct acpi_data_node {
 	const char *name;
 	acpi_handle handle;
 	struct fwnode_handle fwnode;
+	struct fwnode_handle *parent;
 	struct acpi_device_data data;
 	struct list_head sibling;
 	struct kobject kobj;
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 07f8924a2dfd..91407f2d549f 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -998,8 +998,16 @@ int acpi_node_prop_read(struct fwnode_handle *fwnode, const char *propname,
 int acpi_dev_prop_read(struct acpi_device *adev, const char *propname,
 		       enum dev_prop_type proptype, void *val, size_t nval);
 
-struct fwnode_handle *acpi_get_next_subnode(struct device *dev,
-					    struct fwnode_handle *subnode);
+struct fwnode_handle *acpi_get_next_subnode(struct fwnode_handle *fwnode,
+					    struct fwnode_handle *child);
+struct fwnode_handle *acpi_node_get_parent(struct fwnode_handle *fwnode);
+
+struct fwnode_handle *acpi_graph_get_next_endpoint(struct fwnode_handle *fwnode,
+						   struct fwnode_handle *prev);
+int acpi_graph_get_remote_endpoint(struct fwnode_handle *fwnode,
+				   struct fwnode_handle **remote,
+				   struct fwnode_handle **port,
+				   struct fwnode_handle **endpoint);
 
 struct acpi_probe_entry;
 typedef bool (*acpi_probe_entry_validate_subtbl)(struct acpi_subtable_header *,
@@ -1116,12 +1124,34 @@ static inline int acpi_dev_prop_read(struct acpi_device *adev,
 	return -ENXIO;
 }
 
-static inline struct fwnode_handle *acpi_get_next_subnode(struct device *dev,
-						struct fwnode_handle *subnode)
+static inline struct fwnode_handle *
+acpi_get_next_subnode(struct fwnode_handle *fwnode, struct fwnode_handle *child)
 {
 	return NULL;
 }
 
+static inline struct fwnode_handle *
+acpi_node_get_parent(struct fwnode_handle *fwnode)
+{
+	return NULL;
+}
+
+static inline struct fwnode_handle *
+acpi_graph_get_next_endpoint(struct fwnode_handle *fwnode,
+			     struct fwnode_handle *prev)
+{
+	return ERR_PTR(-ENXIO);
+}
+
+static inline int
+acpi_graph_get_remote_endpoint(struct fwnode_handle *fwnode,
+			       struct fwnode_handle **remote,
+			       struct fwnode_handle **port,
+			       struct fwnode_handle **endpoint)
+{
+	return -ENXIO;
+}
+
 #define ACPI_DECLARE_PROBE_ENTRY(table, name, table_id, subtable, valid, data, fn) \
 	static const void * __acpi_table_##name[]			\
 		__attribute__((unused))					\
diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h
index 8bd28ce6d76e..3dff2398a5f0 100644
--- a/include/linux/fwnode.h
+++ b/include/linux/fwnode.h
@@ -27,4 +27,16 @@ struct fwnode_handle {
 	struct fwnode_handle *secondary;
 };
 
+/**
+ * struct fwnode_endpoint - Fwnode graph endpoint
+ * @port: Port number
+ * @id: Endpoint id
+ * @local_fwnode: reference to the related fwnode
+ */
+struct fwnode_endpoint {
+	unsigned int port;
+	unsigned int id;
+	const struct fwnode_handle *local_fwnode;
+};
+
 #endif
diff --git a/include/linux/of.h b/include/linux/of.h
index 21e6323de0f3..e5d4225fda35 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -159,6 +159,8 @@ static inline struct device_node *to_of_node(struct fwnode_handle *fwnode)
 		container_of(fwnode, struct device_node, fwnode) : NULL;
 }
 
+#define of_fwnode_handle(node) (&(node)->fwnode)
+
 static inline bool of_have_populated_dt(void)
 {
 	return of_root != NULL;
@@ -602,6 +604,8 @@ static inline struct device_node *of_find_node_with_property(
 	return NULL;
 }
 
+#define of_fwnode_handle(node) NULL
+
 static inline bool of_have_populated_dt(void)
 {
 	return false;
diff --git a/include/linux/property.h b/include/linux/property.h
index 64e3a9c6d95f..2f482616a2f2 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -33,6 +33,8 @@ enum dev_dma_attr {
 	DEV_DMA_COHERENT,
 };
 
+struct fwnode_handle *dev_fwnode(struct device *dev);
+
 bool device_property_present(struct device *dev, const char *propname);
 int device_property_read_u8_array(struct device *dev, const char *propname,
 				  u8 *val, size_t nval);
@@ -70,6 +72,15 @@ int fwnode_property_read_string(struct fwnode_handle *fwnode,
 int fwnode_property_match_string(struct fwnode_handle *fwnode,
 				 const char *propname, const char *string);
 
+struct fwnode_handle *fwnode_get_parent(struct fwnode_handle *fwnode);
+struct fwnode_handle *fwnode_get_next_parent(struct fwnode_handle *fwnode);
+struct fwnode_handle *fwnode_get_next_child_node(struct fwnode_handle *fwnode,
+						 struct fwnode_handle *child);
+
+#define fwnode_for_each_child_node(fwnode, child)			\
+	for (child = fwnode_get_next_child_node(fwnode, NULL); child;	\
+	     child = fwnode_get_next_child_node(fwnode, child))
+
 struct fwnode_handle *device_get_next_child_node(struct device *dev,
 						 struct fwnode_handle *child);
 
@@ -77,9 +88,12 @@ struct fwnode_handle *device_get_next_child_node(struct device *dev,
 	for (child = device_get_next_child_node(dev, NULL); child;	\
 	     child = device_get_next_child_node(dev, child))
 
+struct fwnode_handle *fwnode_get_named_child_node(struct fwnode_handle *fwnode,
+						  const char *childname);
 struct fwnode_handle *device_get_named_child_node(struct device *dev,
 						  const char *childname);
 
+void fwnode_handle_get(struct fwnode_handle *fwnode);
 void fwnode_handle_put(struct fwnode_handle *fwnode);
 
 unsigned int device_get_child_node_count(struct device *dev);
@@ -258,4 +272,16 @@ int device_get_phy_mode(struct device *dev);
 
 void *device_get_mac_address(struct device *dev, char *addr, int alen);
 
+struct fwnode_handle *fwnode_graph_get_next_endpoint(
+	struct fwnode_handle *fwnode, struct fwnode_handle *prev);
+struct fwnode_handle *fwnode_graph_get_remote_port_parent(
+	struct fwnode_handle *fwnode);
+struct fwnode_handle *fwnode_graph_get_remote_port(
+	struct fwnode_handle *fwnode);
+struct fwnode_handle *fwnode_graph_get_remote_endpoint(
+	struct fwnode_handle *fwnode);
+
+int fwnode_graph_parse_endpoint(struct fwnode_handle *fwnode,
+				struct fwnode_endpoint *endpoint);
+
 #endif /* _LINUX_PROPERTY_H_ */