145 lines
4.4 KiB
C
145 lines
4.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* API for creating and destroying USB onboard platform devices
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*
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* Copyright (c) 2022, Google LLC
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*/
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#include <linux/device.h>
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <linux/of.h>
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#include <linux/of_platform.h>
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#include <linux/platform_device.h>
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#include <linux/usb.h>
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#include <linux/usb/hcd.h>
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#include <linux/usb/of.h>
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#include <linux/usb/onboard_dev.h>
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#include "onboard_usb_dev.h"
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struct pdev_list_entry {
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struct platform_device *pdev;
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struct list_head node;
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};
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static bool of_is_onboard_usb_dev(struct device_node *np)
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{
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return !!of_match_node(onboard_dev_match, np);
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}
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/**
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* onboard_dev_create_pdevs -- create platform devices for onboard USB devices
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* @parent_hub : parent hub to scan for connected onboard devices
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* @pdev_list : list of onboard platform devices owned by the parent hub
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*
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* Creates a platform device for each supported onboard device that is connected
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* to the given parent hub. The platform device is in charge of initializing the
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* device (enable regulators, take the device out of reset, ...). For onboard
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* hubs, it can optionally control whether the device remains powered during
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* system suspend or not.
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*
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* To keep track of the platform devices they are added to a list that is owned
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* by the parent hub.
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*
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* Some background about the logic in this function, which can be a bit hard
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* to follow:
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*
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* Root hubs don't have dedicated device tree nodes, but use the node of their
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* HCD. The primary and secondary HCD are usually represented by a single DT
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* node. That means the root hubs of the primary and secondary HCD share the
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* same device tree node (the HCD node). As a result this function can be called
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* twice with the same DT node for root hubs. We only want to create a single
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* platform device for each physical onboard device, hence for root hubs the
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* loop is only executed for the root hub of the primary HCD. Since the function
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* scans through all child nodes it still creates pdevs for onboard devices
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* connected to the root hub of the secondary HCD if needed.
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*
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* Further there must be only one platform device for onboard hubs with a peer
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* hub (the hub is a single physical device). To achieve this two measures are
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* taken: pdevs for onboard hubs with a peer are only created when the function
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* is called on behalf of the parent hub that is connected to the primary HCD
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* (directly or through other hubs). For onboard hubs connected to root hubs
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* the function processes the nodes of both peers. A platform device is only
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* created if the peer hub doesn't have one already.
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*/
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void onboard_dev_create_pdevs(struct usb_device *parent_hub, struct list_head *pdev_list)
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{
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int i;
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struct usb_hcd *hcd = bus_to_hcd(parent_hub->bus);
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struct device_node *np, *npc;
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struct platform_device *pdev;
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struct pdev_list_entry *pdle;
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if (!parent_hub->dev.of_node)
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return;
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if (!parent_hub->parent && !usb_hcd_is_primary_hcd(hcd))
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return;
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for (i = 1; i <= parent_hub->maxchild; i++) {
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np = usb_of_get_device_node(parent_hub, i);
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if (!np)
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continue;
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if (!of_is_onboard_usb_dev(np))
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goto node_put;
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npc = of_parse_phandle(np, "peer-hub", 0);
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if (npc) {
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if (!usb_hcd_is_primary_hcd(hcd)) {
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of_node_put(npc);
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goto node_put;
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}
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pdev = of_find_device_by_node(npc);
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of_node_put(npc);
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if (pdev) {
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put_device(&pdev->dev);
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goto node_put;
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}
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}
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pdev = of_platform_device_create(np, NULL, &parent_hub->dev);
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if (!pdev) {
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dev_err(&parent_hub->dev,
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"failed to create platform device for onboard dev '%pOF'\n", np);
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goto node_put;
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}
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pdle = kzalloc(sizeof(*pdle), GFP_KERNEL);
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if (!pdle) {
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of_platform_device_destroy(&pdev->dev, NULL);
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goto node_put;
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}
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pdle->pdev = pdev;
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list_add(&pdle->node, pdev_list);
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node_put:
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of_node_put(np);
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}
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}
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EXPORT_SYMBOL_GPL(onboard_dev_create_pdevs);
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/**
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* onboard_dev_destroy_pdevs -- free resources of onboard platform devices
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* @pdev_list : list of onboard platform devices
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*
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* Destroys the platform devices in the given list and frees the memory associated
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* with the list entry.
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*/
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void onboard_dev_destroy_pdevs(struct list_head *pdev_list)
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{
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struct pdev_list_entry *pdle, *tmp;
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list_for_each_entry_safe(pdle, tmp, pdev_list, node) {
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list_del(&pdle->node);
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of_platform_device_destroy(&pdle->pdev->dev, NULL);
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kfree(pdle);
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}
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}
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EXPORT_SYMBOL_GPL(onboard_dev_destroy_pdevs);
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