// 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 {
        struct platform_device *pdev;
        struct list_head node;
};

static bool of_is_onboard_usb_dev(struct device_node *np)
{
        return !!of_match_node(onboard_dev_match, 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)
{
        int i;
        struct usb_hcd *hcd = bus_to_hcd(parent_hub->bus);
        struct device_node *np, *npc;
        struct platform_device *pdev;
        struct pdev_list_entry *pdle;

        if (!parent_hub->dev.of_node)
                return;

        if (!parent_hub->parent && !usb_hcd_is_primary_hcd(hcd))
                return;

        for (i = 1; i <= parent_hub->maxchild; i++) {
                np = usb_of_get_device_node(parent_hub, i);
                if (!np)
                        continue;

                if (!of_is_onboard_usb_dev(np))
                        goto node_put;

                npc = of_parse_phandle(np, "peer-hub", 0);
                if (npc) {
                        if (!usb_hcd_is_primary_hcd(hcd)) {
                                of_node_put(npc);
                                goto node_put;
                        }

                        pdev = of_find_device_by_node(npc);
                        of_node_put(npc);

                        if (pdev) {
                                put_device(&pdev->dev);
                                goto node_put;
                        }
                }

                pdev = of_platform_device_create(np, NULL, &parent_hub->dev);
                if (!pdev) {
                        dev_err(&parent_hub->dev,
                                "failed to create platform device for onboard dev '%pOF'\n", np);
                        goto node_put;
                }

                pdle = kzalloc_obj(*pdle);
                if (!pdle) {
                        of_platform_device_destroy(&pdev->dev, NULL);
                        goto node_put;
                }

                pdle->pdev = pdev;
                list_add(&pdle->node, pdev_list);

node_put:
                of_node_put(np);
        }
}
EXPORT_SYMBOL_GPL(onboard_dev_create_pdevs);

/**
 * 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)
{
        struct pdev_list_entry *pdle, *tmp;

        list_for_each_entry_safe(pdle, tmp, pdev_list, node) {
                list_del(&pdle->node);
                of_platform_device_destroy(&pdle->pdev->dev, NULL);
                kfree(pdle);
        }
}
EXPORT_SYMBOL_GPL(onboard_dev_destroy_pdevs);