linux_kernel/drivers/usb/core/of.c

/*
 * of.c		The helpers for hcd device tree support
 *
 * Copyright (C) 2016 Freescale Semiconductor, Inc.
 * Author: Peter Chen <peter.chen@freescale.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2  of
 * the License as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/of.h>

/**
 * usb_of_get_child_node - Find the device node match port number
 * @parent: the parent device node
 * @portnum: the port number which device is connecting
 *
 * Find the node from device tree according to its port number.
 *
 * Return: On success, a pointer to the device node, %NULL on failure.
 */
struct device_node *usb_of_get_child_node(struct device_node *parent,
					int portnum)
{
	struct device_node *node;
	u32 port;

	for_each_child_of_node(parent, node) {
		if (!of_property_read_u32(node, "reg", &port)) {
			if (port == portnum)
				return node;
		}
	}

	return NULL;
}
EXPORT_SYMBOL_GPL(usb_of_get_child_node);