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
 22struct pdev_list_entry {
 23	struct platform_device *pdev;
 24	struct list_head node;
 25};
 26
 27static 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 */
 66void 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
120node_put:
121		of_node_put(np);
122	}
123}
124EXPORT_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 */
133void 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}
143EXPORT_SYMBOL_GPL(onboard_hub_destroy_pdevs);