linux/drivers/usb/core/of.c
Johan Hovold 60a93cffcf USB: of: document reference taken by child-lookup helper
Document that the child-node lookup helper takes a reference to the
device-tree node which needs to be dropped after use.

Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-06-13 11:07:32 +02:00

76 lines
2.1 KiB
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>
#include <linux/of_platform.h>
#include <linux/usb/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: A pointer to the node with incremented refcount if found, or
* %NULL otherwise.
*/
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);
/**
* usb_of_get_companion_dev - Find the companion device
* @dev: the device pointer to find a companion
*
* Find the companion device from platform bus.
*
* Takes a reference to the returned struct device which needs to be dropped
* after use.
*
* Return: On success, a pointer to the companion device, %NULL on failure.
*/
struct device *usb_of_get_companion_dev(struct device *dev)
{
struct device_node *node;
struct platform_device *pdev = NULL;
node = of_parse_phandle(dev->of_node, "companion", 0);
if (node)
pdev = of_find_device_by_node(node);
of_node_put(node);
return pdev ? &pdev->dev : NULL;
}
EXPORT_SYMBOL_GPL(usb_of_get_companion_dev);