diff options
Diffstat (limited to 'drivers/usb/misc/onboard_usb_dev_pdevs.c')
| -rw-r--r-- | drivers/usb/misc/onboard_usb_dev_pdevs.c | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/drivers/usb/misc/onboard_usb_dev_pdevs.c b/drivers/usb/misc/onboard_usb_dev_pdevs.c new file mode 100644 index 000000000000..722504752ce3 --- /dev/null +++ b/drivers/usb/misc/onboard_usb_dev_pdevs.c @@ -0,0 +1,144 @@ +// 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(sizeof(*pdle), GFP_KERNEL); + 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); |