linux-kernel - [PATCH v1 13/18] driver core: Add fwnode_get_next_parent

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Message-Id: <20201104232356.4038506-14-saravanak@google.com>
Date:   Wed,  4 Nov 2020 15:23:50 -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 v1 13/18] driver core: Add fwnode_get_next_parent_dev() helper function

Given a fwnode, this function finds the closest ancestor fwnode that has
a corresponding struct device. The function returns this struct device.
This function will be used in a subsequent patch in this series.

Signed-off-by: Saravana Kannan <saravanak@...gle.com>
---
 drivers/base/core.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index ee28d8c7ee85..4ae5f2885ac5 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1562,6 +1562,31 @@ static void fw_devlink_parse_fwtree(struct fwnode_handle *fwnode)
 		fw_devlink_parse_fwtree(child);
 }
 
+/**
+ * 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.
+ */
+static 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;
+}
+
 static void fw_devlink_link_device(struct device *dev)
 {
 	int fw_ret;
-- 
2.29.1.341.ge80a0c044ae-goog