// SPDX-License-Identifier: GPL-2.0-only /* * API for creating and destroying USB onboard platform devices * * Copyright (c) 2022, Google LLC */ #include <linux/device.h> #include <linux/export.h> #include <linux/kernel.h> #include <linux/list.h> #include <linux/of.h> #include <linux/of_platform.h> #include <linux/platform_device.h> #include <linux/usb.h> #include <linux/usb/hcd.h> #include <linux/usb/of.h> #include <linux/usb/onboard_dev.h> #include "onboard_usb_dev.h" struct pdev_list_entry { … }; static bool of_is_onboard_usb_dev(struct device_node *np) { … } /** * onboard_dev_create_pdevs -- create platform devices for onboard USB devices * @parent_hub : parent hub to scan for connected onboard devices * @pdev_list : list of onboard platform devices owned by the parent hub * * Creates a platform device for each supported onboard device that is connected * to the given parent hub. The platform device is in charge of initializing the * device (enable regulators, take the device out of reset, ...). For onboard * hubs, it can optionally control whether the device remains powered during * system suspend or not. * * To keep track of the platform devices they are added to a list that is owned * by the parent hub. * * Some background about the logic in this function, which can be a bit hard * to follow: * * Root hubs don't have dedicated device tree nodes, but use the node of their * HCD. The primary and secondary HCD are usually represented by a single DT * node. That means the root hubs of the primary and secondary HCD share the * same device tree node (the HCD node). As a result this function can be called * twice with the same DT node for root hubs. We only want to create a single * platform device for each physical onboard device, hence for root hubs the * loop is only executed for the root hub of the primary HCD. Since the function * scans through all child nodes it still creates pdevs for onboard devices * connected to the root hub of the secondary HCD if needed. * * Further there must be only one platform device for onboard hubs with a peer * hub (the hub is a single physical device). To achieve this two measures are * taken: pdevs for onboard hubs with a peer are only created when the function * is called on behalf of the parent hub that is connected to the primary HCD * (directly or through other hubs). For onboard hubs connected to root hubs * the function processes the nodes of both peers. A platform device is only * created if the peer hub doesn't have one already. */ void onboard_dev_create_pdevs(struct usb_device *parent_hub, struct list_head *pdev_list) { … } EXPORT_SYMBOL_GPL(…); /** * onboard_dev_destroy_pdevs -- free resources of onboard platform devices * @pdev_list : list of onboard platform devices * * Destroys the platform devices in the given list and frees the memory associated * with the list entry. */ void onboard_dev_destroy_pdevs(struct list_head *pdev_list) { … } EXPORT_SYMBOL_GPL(…);
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