xref: /kernel/linux/linux-6.6/drivers/usb/core/of.c (revision 62306a36) 
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * of.c		The helpers for hcd device tree support
4 *
5 * Copyright (C) 2016 Freescale Semiconductor, Inc.
6 *	Author: Peter Chen <peter.chen@freescale.com>
7 * Copyright (C) 2017 Johan Hovold <johan@kernel.org>
8 */
9
10#include <linux/of.h>
11#include <linux/usb/of.h>
12
13/**
14 * usb_of_get_device_node() - get a USB device node
15 * @hub: hub to which device is connected
16 * @port1: one-based index of port
17 *
18 * Look up the node of a USB device given its parent hub device and one-based
19 * port number.
20 *
21 * Return: A pointer to the node with incremented refcount if found, or
22 * %NULL otherwise.
23 */
24struct device_node *usb_of_get_device_node(struct usb_device *hub, int port1)
25{
26	struct device_node *node;
27	u32 reg;
28
29	for_each_child_of_node(hub->dev.of_node, node) {
30		if (of_property_read_u32(node, "reg", &reg))
31			continue;
32
33		if (reg == port1)
34			return node;
35	}
36
37	return NULL;
38}
39EXPORT_SYMBOL_GPL(usb_of_get_device_node);
40
41/**
42 * usb_of_has_combined_node() - determine whether a device has a combined node
43 * @udev: USB device
44 *
45 * Determine whether a USB device has a so called combined node which is
46 * shared with its sole interface. This is the case if and only if the device
47 * has a node and its descriptors report the following:
48 *
49 *	1) bDeviceClass is 0 or 9, and
50 *	2) bNumConfigurations is 1, and
51 *	3) bNumInterfaces is 1.
52 *
53 * Return: True iff the device has a device node and its descriptors match the
54 * criteria for a combined node.
55 */
56bool usb_of_has_combined_node(struct usb_device *udev)
57{
58	struct usb_device_descriptor *ddesc = &udev->descriptor;
59	struct usb_config_descriptor *cdesc;
60
61	if (!udev->dev.of_node)
62		return false;
63
64	switch (ddesc->bDeviceClass) {
65	case USB_CLASS_PER_INTERFACE:
66	case USB_CLASS_HUB:
67		if (ddesc->bNumConfigurations == 1) {
68			cdesc = &udev->config->desc;
69			if (cdesc->bNumInterfaces == 1)
70				return true;
71		}
72	}
73
74	return false;
75}
76EXPORT_SYMBOL_GPL(usb_of_has_combined_node);
77
78/**
79 * usb_of_get_interface_node() - get a USB interface node
80 * @udev: USB device of interface
81 * @config: configuration value
82 * @ifnum: interface number
83 *
84 * Look up the node of a USB interface given its USB device, configuration
85 * value and interface number.
86 *
87 * Return: A pointer to the node with incremented refcount if found, or
88 * %NULL otherwise.
89 */
90struct device_node *
91usb_of_get_interface_node(struct usb_device *udev, u8 config, u8 ifnum)
92{
93	struct device_node *node;
94	u32 reg[2];
95
96	for_each_child_of_node(udev->dev.of_node, node) {
97		if (of_property_read_u32_array(node, "reg", reg, 2))
98			continue;
99
100		if (reg[0] == ifnum && reg[1] == config)
101			return node;
102	}
103
104	return NULL;
105}
106EXPORT_SYMBOL_GPL(usb_of_get_interface_node);
107