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