linux-kernel - [PATCH v2 10/17] device property: Add fwnode_is_ancestor_of() and fwnode_get_next_parent

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Message-Id: <20201121020232.908850-11-saravanak@google.com>
Date:   Fri, 20 Nov 2020 18:02:25 -0800
From:   Saravana Kannan <saravanak@...gle.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Saravana Kannan <saravanak@...gle.com>,
        Tomi Valkeinen <tomi.valkeinen@...com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Grygorii Strashko <grygorii.strashko@...com>,
        kernel-team@...roid.com, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: [PATCH v2 10/17] device property: Add fwnode_is_ancestor_of() and fwnode_get_next_parent_dev()

Add fwnode_is_ancestor_of() helper function to check if a fwnode is an
ancestor of another fwnode.

Add fwnode_get_next_parent_dev() helper function that take as input a
fwnode and finds the closest ancestor fwnode that has a corresponding
struct device and returns that struct device.

Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
 drivers/base/property.c  | 52 ++++++++++++++++++++++++++++++++++++++++
 include/linux/property.h |  3 +++
 2 files changed, 55 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index 4c43d30145c6..35b95c6ac0c6 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -614,6 +614,31 @@ struct fwnode_handle *fwnode_get_next_parent(struct fwnode_handle *fwnode)
 }
 EXPORT_SYMBOL_GPL(fwnode_get_next_parent);
 
+/**
+ * fwnode_get_next_parent_dev - Find device of closest ancestor fwnode
+ * @fwnode: firmware node
+ *
+ * Given a firmware node (@fwnode), this function finds its closest ancestor
+ * firmware node that has a corresponding struct device and returns that struct
+ * device.
+ *
+ * The caller of this function is expected to call put_device() on the returned
+ * device when they are done.
+ */
+struct device *fwnode_get_next_parent_dev(struct fwnode_handle *fwnode)
+{
+	struct device *dev = NULL;
+
+	fwnode_handle_get(fwnode);
+	do {
+		fwnode = fwnode_get_next_parent(fwnode);
+		if (fwnode)
+			dev = get_dev_from_fwnode(fwnode);
+	} while (fwnode && !dev);
+	fwnode_handle_put(fwnode);
+	return dev;
+}
+
 /**
  * fwnode_count_parents - Return the number of parents a node has
  * @fwnode: The node the parents of which are to be counted
@@ -660,6 +685,33 @@ struct fwnode_handle *fwnode_get_nth_parent(struct fwnode_handle *fwnode,
 }
 EXPORT_SYMBOL_GPL(fwnode_get_nth_parent);
 
+/**
+ * fwnode_is_ancestor_of - Test if @test_ancestor is ancestor of @test_child
+ * @test_ancestor: Firmware which is tested for being an ancestor
+ * @test_child: Firmware which is tested for being the child
+ *
+ * A node is considered an ancestor of itself too.
+ *
+ * Returns true if @test_ancestor is an ancestor of @test_child.
+ * Otherwise, returns false.
+ */
+bool fwnode_is_ancestor_of(struct fwnode_handle *test_ancestor,
+				  struct fwnode_handle *test_child)
+{
+	if (!test_ancestor)
+		return false;
+
+	fwnode_handle_get(test_child);
+	while (test_child) {
+		if (test_child == test_ancestor) {
+			fwnode_handle_put(test_child);
+			return true;
+		}
+		test_child = fwnode_get_next_parent(test_child);
+	}
+	return false;
+}
+
 /**
  * fwnode_get_next_child_node - Return the next child node handle for a node
  * @fwnode: Firmware node to find the next child node for.
diff --git a/include/linux/property.h b/include/linux/property.h
index 2d4542629d80..0a9001fe7aea 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -85,9 +85,12 @@ const char *fwnode_get_name_prefix(const struct fwnode_handle *fwnode);
 struct fwnode_handle *fwnode_get_parent(const struct fwnode_handle *fwnode);
 struct fwnode_handle *fwnode_get_next_parent(
 	struct fwnode_handle *fwnode);
+struct device *fwnode_get_next_parent_dev(struct fwnode_handle *fwnode);
 unsigned int fwnode_count_parents(const struct fwnode_handle *fwn);
 struct fwnode_handle *fwnode_get_nth_parent(struct fwnode_handle *fwn,
 					    unsigned int depth);
+bool fwnode_is_ancestor_of(struct fwnode_handle *test_ancestor,
+				  struct fwnode_handle *test_child);
 struct fwnode_handle *fwnode_get_next_child_node(
 	const struct fwnode_handle *fwnode, struct fwnode_handle *child);
 struct fwnode_handle *fwnode_get_next_available_child_node(
-- 
2.29.2.454.gaff20da3a2-goog