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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 | // SPDX-License-Identifier: GPL-2.0 /* * dev-path-parser.c - EFI Device Path parser * Copyright (C) 2016 Lukas Wunner <lukas@wunner.de> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License (version 2) as * published by the Free Software Foundation. */ #include <linux/acpi.h> #include <linux/efi.h> #include <linux/pci.h> static long __init parse_acpi_path(const struct efi_dev_path *node, struct device *parent, struct device **child) { struct acpi_device *adev; struct device *phys_dev; char hid[ACPI_ID_LEN]; u64 uid; int ret; if (node->header.length != 12) return -EINVAL; sprintf(hid, "%c%c%c%04X", 'A' + ((node->acpi.hid >> 10) & 0x1f) - 1, 'A' + ((node->acpi.hid >> 5) & 0x1f) - 1, 'A' + ((node->acpi.hid >> 0) & 0x1f) - 1, node->acpi.hid >> 16); for_each_acpi_dev_match(adev, hid, NULL, -1) { ret = acpi_dev_uid_to_integer(adev, &uid); if (ret == 0 && node->acpi.uid == uid) break; if (ret == -ENODATA && node->acpi.uid == 0) break; } if (!adev) return -ENODEV; phys_dev = acpi_get_first_physical_node(adev); if (phys_dev) { *child = get_device(phys_dev); acpi_dev_put(adev); } else *child = &adev->dev; return 0; } static int __init match_pci_dev(struct device *dev, void *data) { unsigned int devfn = *(unsigned int *)data; return dev_is_pci(dev) && to_pci_dev(dev)->devfn == devfn; } static long __init parse_pci_path(const struct efi_dev_path *node, struct device *parent, struct device **child) { unsigned int devfn; if (node->header.length != 6) return -EINVAL; if (!parent) return -EINVAL; devfn = PCI_DEVFN(node->pci.dev, node->pci.fn); *child = device_find_child(parent, &devfn, match_pci_dev); if (!*child) return -ENODEV; return 0; } /* * Insert parsers for further node types here. * * Each parser takes a pointer to the @node and to the @parent (will be NULL * for the first device path node). If a device corresponding to @node was * found below @parent, its reference count should be incremented and the * device returned in @child. * * The return value should be 0 on success or a negative int on failure. * The special return values 0x01 (EFI_DEV_END_INSTANCE) and 0xFF * (EFI_DEV_END_ENTIRE) signal the end of the device path, only * parse_end_path() is supposed to return this. * * Be sure to validate the node length and contents before commencing the * search for a device. */ static long __init parse_end_path(const struct efi_dev_path *node, struct device *parent, struct device **child) { if (node->header.length != 4) return -EINVAL; if (node->header.sub_type != EFI_DEV_END_INSTANCE && node->header.sub_type != EFI_DEV_END_ENTIRE) return -EINVAL; if (!parent) return -ENODEV; *child = get_device(parent); return node->header.sub_type; } /** * efi_get_device_by_path - find device by EFI Device Path * @node: EFI Device Path * @len: maximum length of EFI Device Path in bytes * * Parse a series of EFI Device Path nodes at @node and find the corresponding * device. If the device was found, its reference count is incremented and a * pointer to it is returned. The caller needs to drop the reference with * put_device() after use. The @node pointer is updated to point to the * location immediately after the "End of Hardware Device Path" node. * * If another Device Path instance follows, @len is decremented by the number * of bytes consumed. Otherwise @len is set to %0. * * If a Device Path node is malformed or its corresponding device is not found, * @node is updated to point to this offending node and an ERR_PTR is returned. * * If @len is initially %0, the function returns %NULL. Thus, to iterate over * all instances in a path, the following idiom may be used: * * while (!IS_ERR_OR_NULL(dev = efi_get_device_by_path(&node, &len))) { * // do something with dev * put_device(dev); * } * if (IS_ERR(dev)) * // report error * * Devices can only be found if they're already instantiated. Most buses * instantiate devices in the "subsys" initcall level, hence the earliest * initcall level in which this function should be called is "fs". * * Returns the device on success or * %ERR_PTR(-ENODEV) if no device was found, * %ERR_PTR(-EINVAL) if a node is malformed or exceeds @len, * %ERR_PTR(-ENOTSUPP) if support for a node type is not yet implemented. */ struct device * __init efi_get_device_by_path(const struct efi_dev_path **node, size_t *len) { struct device *parent = NULL, *child; long ret = 0; if (!*len) return NULL; while (!ret) { if (*len < 4 || *len < (*node)->header.length) ret = -EINVAL; else if ((*node)->header.type == EFI_DEV_ACPI && (*node)->header.sub_type == EFI_DEV_BASIC_ACPI) ret = parse_acpi_path(*node, parent, &child); else if ((*node)->header.type == EFI_DEV_HW && (*node)->header.sub_type == EFI_DEV_PCI) ret = parse_pci_path(*node, parent, &child); else if (((*node)->header.type == EFI_DEV_END_PATH || (*node)->header.type == EFI_DEV_END_PATH2)) ret = parse_end_path(*node, parent, &child); else ret = -ENOTSUPP; put_device(parent); if (ret < 0) return ERR_PTR(ret); parent = child; *node = (void *)*node + (*node)->header.length; *len -= (*node)->header.length; } if (ret == EFI_DEV_END_ENTIRE) *len = 0; return child; } |