14febfb8dSArd Biesheuvel // SPDX-License-Identifier: GPL-2.0 246cd4b75SLukas Wunner /* 346cd4b75SLukas Wunner * dev-path-parser.c - EFI Device Path parser 446cd4b75SLukas Wunner * Copyright (C) 2016 Lukas Wunner <lukas@wunner.de> 546cd4b75SLukas Wunner * 646cd4b75SLukas Wunner * This program is free software; you can redistribute it and/or modify 746cd4b75SLukas Wunner * it under the terms of the GNU General Public License (version 2) as 846cd4b75SLukas Wunner * published by the Free Software Foundation. 946cd4b75SLukas Wunner */ 1046cd4b75SLukas Wunner 1146cd4b75SLukas Wunner #include <linux/acpi.h> 1246cd4b75SLukas Wunner #include <linux/efi.h> 1346cd4b75SLukas Wunner #include <linux/pci.h> 1446cd4b75SLukas Wunner 15db8952e7SArd Biesheuvel static long __init parse_acpi_path(const struct efi_dev_path *node, 1646cd4b75SLukas Wunner struct device *parent, struct device **child) 1746cd4b75SLukas Wunner { 18*edbd1bc4SAndy Shevchenko char hid[ACPI_ID_LEN], uid[11]; /* UINT_MAX + null byte */ 19*edbd1bc4SAndy Shevchenko struct acpi_device *adev; 2046cd4b75SLukas Wunner struct device *phys_dev; 2146cd4b75SLukas Wunner 22db8952e7SArd Biesheuvel if (node->header.length != 12) 2346cd4b75SLukas Wunner return -EINVAL; 2446cd4b75SLukas Wunner 25*edbd1bc4SAndy Shevchenko sprintf(hid, "%c%c%c%04X", 2646cd4b75SLukas Wunner 'A' + ((node->acpi.hid >> 10) & 0x1f) - 1, 2746cd4b75SLukas Wunner 'A' + ((node->acpi.hid >> 5) & 0x1f) - 1, 2846cd4b75SLukas Wunner 'A' + ((node->acpi.hid >> 0) & 0x1f) - 1, 2946cd4b75SLukas Wunner node->acpi.hid >> 16); 30*edbd1bc4SAndy Shevchenko sprintf(uid, "%u", node->acpi.uid); 3146cd4b75SLukas Wunner 32*edbd1bc4SAndy Shevchenko for_each_acpi_dev_match(adev, hid, NULL, -1) { 33*edbd1bc4SAndy Shevchenko if (adev->pnp.unique_id && !strcmp(adev->pnp.unique_id, uid)) 34*edbd1bc4SAndy Shevchenko break; 35*edbd1bc4SAndy Shevchenko if (!adev->pnp.unique_id && node->acpi.uid == 0) 36*edbd1bc4SAndy Shevchenko break; 37*edbd1bc4SAndy Shevchenko acpi_dev_put(adev); 38*edbd1bc4SAndy Shevchenko } 39*edbd1bc4SAndy Shevchenko if (!adev) 4046cd4b75SLukas Wunner return -ENODEV; 4146cd4b75SLukas Wunner 42*edbd1bc4SAndy Shevchenko phys_dev = acpi_get_first_physical_node(adev); 4346cd4b75SLukas Wunner if (phys_dev) { 44*edbd1bc4SAndy Shevchenko *child = get_device(phys_dev); 45*edbd1bc4SAndy Shevchenko acpi_dev_put(adev); 46*edbd1bc4SAndy Shevchenko } else 47*edbd1bc4SAndy Shevchenko *child = &adev->dev; 4846cd4b75SLukas Wunner 4946cd4b75SLukas Wunner return 0; 5046cd4b75SLukas Wunner } 5146cd4b75SLukas Wunner 5246cd4b75SLukas Wunner static int __init match_pci_dev(struct device *dev, void *data) 5346cd4b75SLukas Wunner { 5446cd4b75SLukas Wunner unsigned int devfn = *(unsigned int *)data; 5546cd4b75SLukas Wunner 5646cd4b75SLukas Wunner return dev_is_pci(dev) && to_pci_dev(dev)->devfn == devfn; 5746cd4b75SLukas Wunner } 5846cd4b75SLukas Wunner 59db8952e7SArd Biesheuvel static long __init parse_pci_path(const struct efi_dev_path *node, 6046cd4b75SLukas Wunner struct device *parent, struct device **child) 6146cd4b75SLukas Wunner { 6246cd4b75SLukas Wunner unsigned int devfn; 6346cd4b75SLukas Wunner 64db8952e7SArd Biesheuvel if (node->header.length != 6) 6546cd4b75SLukas Wunner return -EINVAL; 6646cd4b75SLukas Wunner if (!parent) 6746cd4b75SLukas Wunner return -EINVAL; 6846cd4b75SLukas Wunner 6946cd4b75SLukas Wunner devfn = PCI_DEVFN(node->pci.dev, node->pci.fn); 7046cd4b75SLukas Wunner 7146cd4b75SLukas Wunner *child = device_find_child(parent, &devfn, match_pci_dev); 7246cd4b75SLukas Wunner if (!*child) 7346cd4b75SLukas Wunner return -ENODEV; 7446cd4b75SLukas Wunner 7546cd4b75SLukas Wunner return 0; 7646cd4b75SLukas Wunner } 7746cd4b75SLukas Wunner 7846cd4b75SLukas Wunner /* 7946cd4b75SLukas Wunner * Insert parsers for further node types here. 8046cd4b75SLukas Wunner * 8146cd4b75SLukas Wunner * Each parser takes a pointer to the @node and to the @parent (will be NULL 8246cd4b75SLukas Wunner * for the first device path node). If a device corresponding to @node was 8346cd4b75SLukas Wunner * found below @parent, its reference count should be incremented and the 8446cd4b75SLukas Wunner * device returned in @child. 8546cd4b75SLukas Wunner * 8646cd4b75SLukas Wunner * The return value should be 0 on success or a negative int on failure. 8746cd4b75SLukas Wunner * The special return values 0x01 (EFI_DEV_END_INSTANCE) and 0xFF 8846cd4b75SLukas Wunner * (EFI_DEV_END_ENTIRE) signal the end of the device path, only 8946cd4b75SLukas Wunner * parse_end_path() is supposed to return this. 9046cd4b75SLukas Wunner * 9146cd4b75SLukas Wunner * Be sure to validate the node length and contents before commencing the 9246cd4b75SLukas Wunner * search for a device. 9346cd4b75SLukas Wunner */ 9446cd4b75SLukas Wunner 95db8952e7SArd Biesheuvel static long __init parse_end_path(const struct efi_dev_path *node, 9646cd4b75SLukas Wunner struct device *parent, struct device **child) 9746cd4b75SLukas Wunner { 98db8952e7SArd Biesheuvel if (node->header.length != 4) 9946cd4b75SLukas Wunner return -EINVAL; 100db8952e7SArd Biesheuvel if (node->header.sub_type != EFI_DEV_END_INSTANCE && 101db8952e7SArd Biesheuvel node->header.sub_type != EFI_DEV_END_ENTIRE) 10246cd4b75SLukas Wunner return -EINVAL; 10346cd4b75SLukas Wunner if (!parent) 10446cd4b75SLukas Wunner return -ENODEV; 10546cd4b75SLukas Wunner 10646cd4b75SLukas Wunner *child = get_device(parent); 107db8952e7SArd Biesheuvel return node->header.sub_type; 10846cd4b75SLukas Wunner } 10946cd4b75SLukas Wunner 11046cd4b75SLukas Wunner /** 11146cd4b75SLukas Wunner * efi_get_device_by_path - find device by EFI Device Path 11246cd4b75SLukas Wunner * @node: EFI Device Path 11346cd4b75SLukas Wunner * @len: maximum length of EFI Device Path in bytes 11446cd4b75SLukas Wunner * 11546cd4b75SLukas Wunner * Parse a series of EFI Device Path nodes at @node and find the corresponding 11646cd4b75SLukas Wunner * device. If the device was found, its reference count is incremented and a 11746cd4b75SLukas Wunner * pointer to it is returned. The caller needs to drop the reference with 11846cd4b75SLukas Wunner * put_device() after use. The @node pointer is updated to point to the 11946cd4b75SLukas Wunner * location immediately after the "End of Hardware Device Path" node. 12046cd4b75SLukas Wunner * 12146cd4b75SLukas Wunner * If another Device Path instance follows, @len is decremented by the number 12246cd4b75SLukas Wunner * of bytes consumed. Otherwise @len is set to %0. 12346cd4b75SLukas Wunner * 12446cd4b75SLukas Wunner * If a Device Path node is malformed or its corresponding device is not found, 12546cd4b75SLukas Wunner * @node is updated to point to this offending node and an ERR_PTR is returned. 12646cd4b75SLukas Wunner * 12746cd4b75SLukas Wunner * If @len is initially %0, the function returns %NULL. Thus, to iterate over 12846cd4b75SLukas Wunner * all instances in a path, the following idiom may be used: 12946cd4b75SLukas Wunner * 13046cd4b75SLukas Wunner * while (!IS_ERR_OR_NULL(dev = efi_get_device_by_path(&node, &len))) { 13146cd4b75SLukas Wunner * // do something with dev 13246cd4b75SLukas Wunner * put_device(dev); 13346cd4b75SLukas Wunner * } 13446cd4b75SLukas Wunner * if (IS_ERR(dev)) 13546cd4b75SLukas Wunner * // report error 13646cd4b75SLukas Wunner * 13746cd4b75SLukas Wunner * Devices can only be found if they're already instantiated. Most buses 13846cd4b75SLukas Wunner * instantiate devices in the "subsys" initcall level, hence the earliest 13946cd4b75SLukas Wunner * initcall level in which this function should be called is "fs". 14046cd4b75SLukas Wunner * 14146cd4b75SLukas Wunner * Returns the device on success or 14246cd4b75SLukas Wunner * %ERR_PTR(-ENODEV) if no device was found, 14346cd4b75SLukas Wunner * %ERR_PTR(-EINVAL) if a node is malformed or exceeds @len, 14446cd4b75SLukas Wunner * %ERR_PTR(-ENOTSUPP) if support for a node type is not yet implemented. 14546cd4b75SLukas Wunner */ 146db8952e7SArd Biesheuvel struct device * __init efi_get_device_by_path(const struct efi_dev_path **node, 14746cd4b75SLukas Wunner size_t *len) 14846cd4b75SLukas Wunner { 14946cd4b75SLukas Wunner struct device *parent = NULL, *child; 15046cd4b75SLukas Wunner long ret = 0; 15146cd4b75SLukas Wunner 15246cd4b75SLukas Wunner if (!*len) 15346cd4b75SLukas Wunner return NULL; 15446cd4b75SLukas Wunner 15546cd4b75SLukas Wunner while (!ret) { 156db8952e7SArd Biesheuvel if (*len < 4 || *len < (*node)->header.length) 15746cd4b75SLukas Wunner ret = -EINVAL; 158db8952e7SArd Biesheuvel else if ((*node)->header.type == EFI_DEV_ACPI && 159db8952e7SArd Biesheuvel (*node)->header.sub_type == EFI_DEV_BASIC_ACPI) 16046cd4b75SLukas Wunner ret = parse_acpi_path(*node, parent, &child); 161db8952e7SArd Biesheuvel else if ((*node)->header.type == EFI_DEV_HW && 162db8952e7SArd Biesheuvel (*node)->header.sub_type == EFI_DEV_PCI) 16346cd4b75SLukas Wunner ret = parse_pci_path(*node, parent, &child); 164db8952e7SArd Biesheuvel else if (((*node)->header.type == EFI_DEV_END_PATH || 165db8952e7SArd Biesheuvel (*node)->header.type == EFI_DEV_END_PATH2)) 16646cd4b75SLukas Wunner ret = parse_end_path(*node, parent, &child); 16746cd4b75SLukas Wunner else 16846cd4b75SLukas Wunner ret = -ENOTSUPP; 16946cd4b75SLukas Wunner 17046cd4b75SLukas Wunner put_device(parent); 17146cd4b75SLukas Wunner if (ret < 0) 17246cd4b75SLukas Wunner return ERR_PTR(ret); 17346cd4b75SLukas Wunner 17446cd4b75SLukas Wunner parent = child; 175db8952e7SArd Biesheuvel *node = (void *)*node + (*node)->header.length; 176db8952e7SArd Biesheuvel *len -= (*node)->header.length; 17746cd4b75SLukas Wunner } 17846cd4b75SLukas Wunner 17946cd4b75SLukas Wunner if (ret == EFI_DEV_END_ENTIRE) 18046cd4b75SLukas Wunner *len = 0; 18146cd4b75SLukas Wunner 18246cd4b75SLukas Wunner return child; 18346cd4b75SLukas Wunner } 184