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