2019-02-02 02:41:15 -07:00
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// SPDX-License-Identifier: GPL-2.0
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2016-11-12 14:32:34 -07:00
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/*
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* dev-path-parser.c - EFI Device Path parser
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* Copyright (C) 2016 Lukas Wunner <lukas@wunner.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License (version 2) as
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* published by the Free Software Foundation.
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*/
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#include <linux/acpi.h>
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#include <linux/efi.h>
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#include <linux/pci.h>
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struct acpi_hid_uid {
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struct acpi_device_id hid[2];
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char uid[11]; /* UINT_MAX + null byte */
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};
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static int __init match_acpi_dev(struct device *dev, void *data)
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{
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struct acpi_hid_uid hid_uid = *(struct acpi_hid_uid *)data;
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struct acpi_device *adev = to_acpi_device(dev);
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if (acpi_match_device_ids(adev, hid_uid.hid))
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return 0;
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if (adev->pnp.unique_id)
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return !strcmp(adev->pnp.unique_id, hid_uid.uid);
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else
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return !strcmp("0", hid_uid.uid);
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}
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static long __init parse_acpi_path(struct efi_dev_path *node,
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struct device *parent, struct device **child)
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{
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struct acpi_hid_uid hid_uid = {};
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struct device *phys_dev;
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if (node->length != 12)
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return -EINVAL;
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sprintf(hid_uid.hid[0].id, "%c%c%c%04X",
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'A' + ((node->acpi.hid >> 10) & 0x1f) - 1,
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'A' + ((node->acpi.hid >> 5) & 0x1f) - 1,
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'A' + ((node->acpi.hid >> 0) & 0x1f) - 1,
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node->acpi.hid >> 16);
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sprintf(hid_uid.uid, "%u", node->acpi.uid);
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*child = bus_find_device(&acpi_bus_type, NULL, &hid_uid,
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match_acpi_dev);
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if (!*child)
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return -ENODEV;
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phys_dev = acpi_get_first_physical_node(to_acpi_device(*child));
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if (phys_dev) {
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get_device(phys_dev);
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put_device(*child);
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*child = phys_dev;
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}
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return 0;
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}
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static int __init match_pci_dev(struct device *dev, void *data)
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{
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unsigned int devfn = *(unsigned int *)data;
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return dev_is_pci(dev) && to_pci_dev(dev)->devfn == devfn;
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}
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static long __init parse_pci_path(struct efi_dev_path *node,
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struct device *parent, struct device **child)
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{
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unsigned int devfn;
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if (node->length != 6)
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return -EINVAL;
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if (!parent)
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return -EINVAL;
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devfn = PCI_DEVFN(node->pci.dev, node->pci.fn);
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*child = device_find_child(parent, &devfn, match_pci_dev);
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if (!*child)
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return -ENODEV;
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return 0;
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}
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/*
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* Insert parsers for further node types here.
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*
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* Each parser takes a pointer to the @node and to the @parent (will be NULL
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* for the first device path node). If a device corresponding to @node was
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* found below @parent, its reference count should be incremented and the
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* device returned in @child.
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*
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* The return value should be 0 on success or a negative int on failure.
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* The special return values 0x01 (EFI_DEV_END_INSTANCE) and 0xFF
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* (EFI_DEV_END_ENTIRE) signal the end of the device path, only
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* parse_end_path() is supposed to return this.
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*
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* Be sure to validate the node length and contents before commencing the
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* search for a device.
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*/
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static long __init parse_end_path(struct efi_dev_path *node,
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struct device *parent, struct device **child)
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{
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if (node->length != 4)
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return -EINVAL;
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if (node->sub_type != EFI_DEV_END_INSTANCE &&
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node->sub_type != EFI_DEV_END_ENTIRE)
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return -EINVAL;
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if (!parent)
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return -ENODEV;
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*child = get_device(parent);
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return node->sub_type;
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}
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/**
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* efi_get_device_by_path - find device by EFI Device Path
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* @node: EFI Device Path
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* @len: maximum length of EFI Device Path in bytes
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*
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* Parse a series of EFI Device Path nodes at @node and find the corresponding
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* device. If the device was found, its reference count is incremented and a
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* pointer to it is returned. The caller needs to drop the reference with
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* put_device() after use. The @node pointer is updated to point to the
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* location immediately after the "End of Hardware Device Path" node.
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*
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* If another Device Path instance follows, @len is decremented by the number
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* of bytes consumed. Otherwise @len is set to %0.
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*
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* If a Device Path node is malformed or its corresponding device is not found,
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* @node is updated to point to this offending node and an ERR_PTR is returned.
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*
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* If @len is initially %0, the function returns %NULL. Thus, to iterate over
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* all instances in a path, the following idiom may be used:
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*
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* while (!IS_ERR_OR_NULL(dev = efi_get_device_by_path(&node, &len))) {
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* // do something with dev
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* put_device(dev);
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* }
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* if (IS_ERR(dev))
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* // report error
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*
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* Devices can only be found if they're already instantiated. Most buses
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* instantiate devices in the "subsys" initcall level, hence the earliest
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* initcall level in which this function should be called is "fs".
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*
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* Returns the device on success or
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* %ERR_PTR(-ENODEV) if no device was found,
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* %ERR_PTR(-EINVAL) if a node is malformed or exceeds @len,
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* %ERR_PTR(-ENOTSUPP) if support for a node type is not yet implemented.
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*/
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struct device * __init efi_get_device_by_path(struct efi_dev_path **node,
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size_t *len)
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{
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struct device *parent = NULL, *child;
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long ret = 0;
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if (!*len)
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return NULL;
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while (!ret) {
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if (*len < 4 || *len < (*node)->length)
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ret = -EINVAL;
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else if ((*node)->type == EFI_DEV_ACPI &&
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(*node)->sub_type == EFI_DEV_BASIC_ACPI)
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ret = parse_acpi_path(*node, parent, &child);
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else if ((*node)->type == EFI_DEV_HW &&
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(*node)->sub_type == EFI_DEV_PCI)
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ret = parse_pci_path(*node, parent, &child);
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else if (((*node)->type == EFI_DEV_END_PATH ||
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(*node)->type == EFI_DEV_END_PATH2))
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ret = parse_end_path(*node, parent, &child);
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else
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ret = -ENOTSUPP;
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put_device(parent);
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if (ret < 0)
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return ERR_PTR(ret);
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parent = child;
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*node = (void *)*node + (*node)->length;
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*len -= (*node)->length;
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}
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if (ret == EFI_DEV_END_ENTIRE)
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*len = 0;
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return child;
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}
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