1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * API for creating and destroying USB onboard platform devices
4 *
5 * Copyright (c) 2022, Google LLC
6 */
7
8#include <linux/device.h>
9#include <linux/export.h>
10#include <linux/kernel.h>
11#include <linux/list.h>
12#include <linux/of.h>
13#include <linux/of_platform.h>
14#include <linux/platform_device.h>
15#include <linux/usb.h>
16#include <linux/usb/hcd.h>
17#include <linux/usb/of.h>
18#include <linux/usb/onboard_dev.h>
19
20#include "onboard_usb_dev.h"
21
22struct pdev_list_entry {
23 struct platform_device *pdev;
24 struct list_head node;
25};
26
27static bool of_is_onboard_usb_dev(struct device_node *np)
28{
29 return !!of_match_node(matches: onboard_dev_match, node: np);
30}
31
32/**
33 * onboard_dev_create_pdevs -- create platform devices for onboard USB devices
34 * @parent_hub : parent hub to scan for connected onboard devices
35 * @pdev_list : list of onboard platform devices owned by the parent hub
36 *
37 * Creates a platform device for each supported onboard device that is connected
38 * to the given parent hub. The platform device is in charge of initializing the
39 * device (enable regulators, take the device out of reset, ...). For onboard
40 * hubs, it can optionally control whether the device remains powered during
41 * system suspend or not.
42 *
43 * To keep track of the platform devices they are added to a list that is owned
44 * by the parent hub.
45 *
46 * Some background about the logic in this function, which can be a bit hard
47 * to follow:
48 *
49 * Root hubs don't have dedicated device tree nodes, but use the node of their
50 * HCD. The primary and secondary HCD are usually represented by a single DT
51 * node. That means the root hubs of the primary and secondary HCD share the
52 * same device tree node (the HCD node). As a result this function can be called
53 * twice with the same DT node for root hubs. We only want to create a single
54 * platform device for each physical onboard device, hence for root hubs the
55 * loop is only executed for the root hub of the primary HCD. Since the function
56 * scans through all child nodes it still creates pdevs for onboard devices
57 * connected to the root hub of the secondary HCD if needed.
58 *
59 * Further there must be only one platform device for onboard hubs with a peer
60 * hub (the hub is a single physical device). To achieve this two measures are
61 * taken: pdevs for onboard hubs with a peer are only created when the function
62 * is called on behalf of the parent hub that is connected to the primary HCD
63 * (directly or through other hubs). For onboard hubs connected to root hubs
64 * the function processes the nodes of both peers. A platform device is only
65 * created if the peer hub doesn't have one already.
66 */
67void onboard_dev_create_pdevs(struct usb_device *parent_hub, struct list_head *pdev_list)
68{
69 int i;
70 struct usb_hcd *hcd = bus_to_hcd(bus: parent_hub->bus);
71 struct device_node *np, *npc;
72 struct platform_device *pdev;
73 struct pdev_list_entry *pdle;
74
75 if (!parent_hub->dev.of_node)
76 return;
77
78 if (!parent_hub->parent && !usb_hcd_is_primary_hcd(hcd))
79 return;
80
81 for (i = 1; i <= parent_hub->maxchild; i++) {
82 np = usb_of_get_device_node(hub: parent_hub, port1: i);
83 if (!np)
84 continue;
85
86 if (!of_is_onboard_usb_dev(np))
87 goto node_put;
88
89 npc = of_parse_phandle(np, phandle_name: "peer-hub", index: 0);
90 if (npc) {
91 if (!usb_hcd_is_primary_hcd(hcd)) {
92 of_node_put(node: npc);
93 goto node_put;
94 }
95
96 pdev = of_find_device_by_node(np: npc);
97 of_node_put(node: npc);
98
99 if (pdev) {
100 put_device(dev: &pdev->dev);
101 goto node_put;
102 }
103 }
104
105 pdev = of_platform_device_create(np, NULL, parent: &parent_hub->dev);
106 if (!pdev) {
107 dev_err(&parent_hub->dev,
108 "failed to create platform device for onboard dev '%pOF'\n", np);
109 goto node_put;
110 }
111
112 pdle = kzalloc(sizeof(*pdle), GFP_KERNEL);
113 if (!pdle) {
114 of_platform_device_destroy(dev: &pdev->dev, NULL);
115 goto node_put;
116 }
117
118 pdle->pdev = pdev;
119 list_add(new: &pdle->node, head: pdev_list);
120
121node_put:
122 of_node_put(node: np);
123 }
124}
125EXPORT_SYMBOL_GPL(onboard_dev_create_pdevs);
126
127/**
128 * onboard_dev_destroy_pdevs -- free resources of onboard platform devices
129 * @pdev_list : list of onboard platform devices
130 *
131 * Destroys the platform devices in the given list and frees the memory associated
132 * with the list entry.
133 */
134void onboard_dev_destroy_pdevs(struct list_head *pdev_list)
135{
136 struct pdev_list_entry *pdle, *tmp;
137
138 list_for_each_entry_safe(pdle, tmp, pdev_list, node) {
139 list_del(entry: &pdle->node);
140 of_platform_device_destroy(dev: &pdle->pdev->dev, NULL);
141 kfree(objp: pdle);
142 }
143}
144EXPORT_SYMBOL_GPL(onboard_dev_destroy_pdevs);
145

source code of linux/drivers/usb/misc/onboard_usb_dev_pdevs.c