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1// SPDX-License-Identifier: GPL-2.02/*3 * Export the firmware instance and label associated with a PCI device to4 * sysfs5 *6 * Copyright (C) 2010 Dell Inc.7 * by Narendra K <Narendra_K@dell.com>,8 * Jordan Hargrave <Jordan_Hargrave@dell.com>9 *10 * PCI Firmware Specification Revision 3.1 section 4.6.7 (DSM for Naming a11 * PCI or PCI Express Device Under Operating Systems) defines an instance12 * number and string name. This code retrieves them and exports them to sysfs.13 * If the system firmware does not provide the ACPI _DSM (Device Specific14 * Method), then the SMBIOS type 41 instance number and string is exported to15 * sysfs.16 *17 * SMBIOS defines type 41 for onboard pci devices. This code retrieves18 * the instance number and string from the type 41 record and exports19 * it to sysfs.20 *21 * Please see https://linux.dell.com/files/biosdevname/ for more22 * information.23 */24 25#include <linux/dmi.h>26#include <linux/sysfs.h>27#include <linux/pci.h>28#include <linux/pci_ids.h>29#include <linux/module.h>30#include <linux/device.h>31#include <linux/nls.h>32#include <linux/acpi.h>33#include <linux/pci-acpi.h>34#include "pci.h"35 36static bool device_has_acpi_name(struct device *dev)37{38#ifdef CONFIG_ACPI39 acpi_handle handle = ACPI_HANDLE(dev);40 41 if (!handle)42 return false;43 44 return acpi_check_dsm(handle, &pci_acpi_dsm_guid, 0x2,45 1 << DSM_PCI_DEVICE_NAME);46#else47 return false;48#endif49}50 51#ifdef CONFIG_DMI52enum smbios_attr_enum {53 SMBIOS_ATTR_NONE = 0,54 SMBIOS_ATTR_LABEL_SHOW,55 SMBIOS_ATTR_INSTANCE_SHOW,56};57 58static size_t find_smbios_instance_string(struct pci_dev *pdev, char *buf,59 enum smbios_attr_enum attribute)60{61 const struct dmi_device *dmi;62 struct dmi_dev_onboard *donboard;63 int domain_nr = pci_domain_nr(pdev->bus);64 int bus = pdev->bus->number;65 int devfn = pdev->devfn;66 67 dmi = NULL;68 while ((dmi = dmi_find_device(DMI_DEV_TYPE_DEV_ONBOARD,69 NULL, dmi)) != NULL) {70 donboard = dmi->device_data;71 if (donboard && donboard->segment == domain_nr &&72 donboard->bus == bus &&73 donboard->devfn == devfn) {74 if (buf) {75 if (attribute == SMBIOS_ATTR_INSTANCE_SHOW)76 return sysfs_emit(buf, "%d\n",77 donboard->instance);78 else if (attribute == SMBIOS_ATTR_LABEL_SHOW)79 return sysfs_emit(buf, "%s\n",80 dmi->name);81 }82 return strlen(dmi->name);83 }84 }85 return 0;86}87 88static ssize_t smbios_label_show(struct device *dev,89 struct device_attribute *attr, char *buf)90{91 struct pci_dev *pdev = to_pci_dev(dev);92 93 return find_smbios_instance_string(pdev, buf,94 SMBIOS_ATTR_LABEL_SHOW);95}96static struct device_attribute dev_attr_smbios_label = __ATTR(label, 0444,97 smbios_label_show, NULL);98 99static ssize_t index_show(struct device *dev, struct device_attribute *attr,100 char *buf)101{102 struct pci_dev *pdev = to_pci_dev(dev);103 104 return find_smbios_instance_string(pdev, buf,105 SMBIOS_ATTR_INSTANCE_SHOW);106}107static DEVICE_ATTR_RO(index);108 109static struct attribute *smbios_attrs[] = {110 &dev_attr_smbios_label.attr,111 &dev_attr_index.attr,112 NULL,113};114 115static umode_t smbios_attr_is_visible(struct kobject *kobj, struct attribute *a,116 int n)117{118 struct device *dev = kobj_to_dev(kobj);119 struct pci_dev *pdev = to_pci_dev(dev);120 121 if (device_has_acpi_name(dev))122 return 0;123 124 if (!find_smbios_instance_string(pdev, NULL, SMBIOS_ATTR_NONE))125 return 0;126 127 return a->mode;128}129 130const struct attribute_group pci_dev_smbios_attr_group = {131 .attrs = smbios_attrs,132 .is_visible = smbios_attr_is_visible,133};134#endif135 136#ifdef CONFIG_ACPI137enum acpi_attr_enum {138 ACPI_ATTR_LABEL_SHOW,139 ACPI_ATTR_INDEX_SHOW,140};141 142static int dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf)143{144 int len;145 146 len = utf16s_to_utf8s((const wchar_t *)obj->buffer.pointer,147 obj->buffer.length,148 UTF16_LITTLE_ENDIAN,149 buf, PAGE_SIZE - 1);150 buf[len++] = '\n';151 152 return len;153}154 155static int dsm_get_label(struct device *dev, char *buf,156 enum acpi_attr_enum attr)157{158 acpi_handle handle = ACPI_HANDLE(dev);159 union acpi_object *obj, *tmp;160 int len = 0;161 162 if (!handle)163 return -1;164 165 obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 0x2,166 DSM_PCI_DEVICE_NAME, NULL);167 if (!obj)168 return -1;169 170 tmp = obj->package.elements;171 if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 2 &&172 tmp[0].type == ACPI_TYPE_INTEGER &&173 (tmp[1].type == ACPI_TYPE_STRING ||174 tmp[1].type == ACPI_TYPE_BUFFER)) {175 /*176 * The second string element is optional even when177 * this _DSM is implemented; when not implemented,178 * this entry must return a null string.179 */180 if (attr == ACPI_ATTR_INDEX_SHOW) {181 len = sysfs_emit(buf, "%llu\n", tmp->integer.value);182 } else if (attr == ACPI_ATTR_LABEL_SHOW) {183 if (tmp[1].type == ACPI_TYPE_STRING)184 len = sysfs_emit(buf, "%s\n",185 tmp[1].string.pointer);186 else if (tmp[1].type == ACPI_TYPE_BUFFER)187 len = dsm_label_utf16s_to_utf8s(tmp + 1, buf);188 }189 }190 191 ACPI_FREE(obj);192 193 return len > 0 ? len : -1;194}195 196static ssize_t label_show(struct device *dev, struct device_attribute *attr,197 char *buf)198{199 return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW);200}201static DEVICE_ATTR_RO(label);202 203static ssize_t acpi_index_show(struct device *dev,204 struct device_attribute *attr, char *buf)205{206 return dsm_get_label(dev, buf, ACPI_ATTR_INDEX_SHOW);207}208static DEVICE_ATTR_RO(acpi_index);209 210static struct attribute *acpi_attrs[] = {211 &dev_attr_label.attr,212 &dev_attr_acpi_index.attr,213 NULL,214};215 216static umode_t acpi_attr_is_visible(struct kobject *kobj, struct attribute *a,217 int n)218{219 struct device *dev = kobj_to_dev(kobj);220 221 if (!device_has_acpi_name(dev))222 return 0;223 224 return a->mode;225}226 227const struct attribute_group pci_dev_acpi_attr_group = {228 .attrs = acpi_attrs,229 .is_visible = acpi_attr_is_visible,230};231#endif232