drivers/pci/pci-label.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Export the firmware instance and label associated with a PCI device to
0004  * sysfs
0005  *
0006  * Copyright (C) 2010 Dell Inc.
0007  * by Narendra K <Narendra_K@dell.com>,
0008  * Jordan Hargrave <Jordan_Hargrave@dell.com>
0009  *
0010  * PCI Firmware Specification Revision 3.1 section 4.6.7 (DSM for Naming a
0011  * PCI or PCI Express Device Under Operating Systems) defines an instance
0012  * number and string name. This code retrieves them and exports them to sysfs.
0013  * If the system firmware does not provide the ACPI _DSM (Device Specific
0014  * Method), then the SMBIOS type 41 instance number and string is exported to
0015  * sysfs.
0016  *
0017  * SMBIOS defines type 41 for onboard pci devices. This code retrieves
0018  * the instance number and string from the type 41 record and exports
0019  * it to sysfs.
0020  *
0021  * Please see https://linux.dell.com/files/biosdevname/ for more
0022  * information.
0023  */
0024
0025 #include <linux/dmi.h>
0026 #include <linux/sysfs.h>
0027 #include <linux/pci.h>
0028 #include <linux/pci_ids.h>
0029 #include <linux/module.h>
0030 #include <linux/device.h>
0031 #include <linux/nls.h>
0032 #include <linux/acpi.h>
0033 #include <linux/pci-acpi.h>
0034 #include "pci.h"
0035
0036 static bool device_has_acpi_name(struct device *dev)
0037 {
0038 #ifdef CONFIG_ACPI
0039     acpi_handle handle = ACPI_HANDLE(dev);
0040
0041     if (!handle)
0042         return false;
0043
0044     return acpi_check_dsm(handle, &pci_acpi_dsm_guid, 0x2,
0045                   1 << DSM_PCI_DEVICE_NAME);
0046 #else
0047     return false;
0048 #endif
0049 }
0050
0051 #ifdef CONFIG_DMI
0052 enum smbios_attr_enum {
0053     SMBIOS_ATTR_NONE = 0,
0054     SMBIOS_ATTR_LABEL_SHOW,
0055     SMBIOS_ATTR_INSTANCE_SHOW,
0056 };
0057
0058 static size_t find_smbios_instance_string(struct pci_dev *pdev, char *buf,
0059                       enum smbios_attr_enum attribute)
0060 {
0061     const struct dmi_device *dmi;
0062     struct dmi_dev_onboard *donboard;
0063     int domain_nr = pci_domain_nr(pdev->bus);
0064     int bus = pdev->bus->number;
0065     int devfn = pdev->devfn;
0066
0067     dmi = NULL;
0068     while ((dmi = dmi_find_device(DMI_DEV_TYPE_DEV_ONBOARD,
0069                       NULL, dmi)) != NULL) {
0070         donboard = dmi->device_data;
0071         if (donboard && donboard->segment == domain_nr &&
0072                 donboard->bus == bus &&
0073                 donboard->devfn == devfn) {
0074             if (buf) {
0075                 if (attribute == SMBIOS_ATTR_INSTANCE_SHOW)
0076                     return sysfs_emit(buf, "%d\n",
0077                               donboard->instance);
0078                 else if (attribute == SMBIOS_ATTR_LABEL_SHOW)
0079                     return sysfs_emit(buf, "%s\n",
0080                               dmi->name);
0081             }
0082             return strlen(dmi->name);
0083         }
0084     }
0085     return 0;
0086 }
0087
0088 static ssize_t smbios_label_show(struct device *dev,
0089                  struct device_attribute *attr, char *buf)
0090 {
0091     struct pci_dev *pdev = to_pci_dev(dev);
0092
0093     return find_smbios_instance_string(pdev, buf,
0094                        SMBIOS_ATTR_LABEL_SHOW);
0095 }
0096 static struct device_attribute dev_attr_smbios_label = __ATTR(label, 0444,
0097                             smbios_label_show, NULL);
0098
0099 static ssize_t index_show(struct device *dev, struct device_attribute *attr,
0100               char *buf)
0101 {
0102     struct pci_dev *pdev = to_pci_dev(dev);
0103
0104     return find_smbios_instance_string(pdev, buf,
0105                        SMBIOS_ATTR_INSTANCE_SHOW);
0106 }
0107 static DEVICE_ATTR_RO(index);
0108
0109 static struct attribute *smbios_attrs[] = {
0110     &dev_attr_smbios_label.attr,
0111     &dev_attr_index.attr,
0112     NULL,
0113 };
0114
0115 static umode_t smbios_attr_is_visible(struct kobject *kobj, struct attribute *a,
0116                       int n)
0117 {
0118     struct device *dev = kobj_to_dev(kobj);
0119     struct pci_dev *pdev = to_pci_dev(dev);
0120
0121     if (device_has_acpi_name(dev))
0122         return 0;
0123
0124     if (!find_smbios_instance_string(pdev, NULL, SMBIOS_ATTR_NONE))
0125         return 0;
0126
0127     return a->mode;
0128 }
0129
0130 const struct attribute_group pci_dev_smbios_attr_group = {
0131     .attrs = smbios_attrs,
0132     .is_visible = smbios_attr_is_visible,
0133 };
0134 #endif
0135
0136 #ifdef CONFIG_ACPI
0137 enum acpi_attr_enum {
0138     ACPI_ATTR_LABEL_SHOW,
0139     ACPI_ATTR_INDEX_SHOW,
0140 };
0141
0142 static int dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf)
0143 {
0144     int len;
0145
0146     len = utf16s_to_utf8s((const wchar_t *)obj->buffer.pointer,
0147                   obj->buffer.length,
0148                   UTF16_LITTLE_ENDIAN,
0149                   buf, PAGE_SIZE - 1);
0150     buf[len++] = '\n';
0151
0152     return len;
0153 }
0154
0155 static int dsm_get_label(struct device *dev, char *buf,
0156              enum acpi_attr_enum attr)
0157 {
0158     acpi_handle handle = ACPI_HANDLE(dev);
0159     union acpi_object *obj, *tmp;
0160     int len = 0;
0161
0162     if (!handle)
0163         return -1;
0164
0165     obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 0x2,
0166                 DSM_PCI_DEVICE_NAME, NULL);
0167     if (!obj)
0168         return -1;
0169
0170     tmp = obj->package.elements;
0171     if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 2 &&
0172         tmp[0].type == ACPI_TYPE_INTEGER &&
0173         (tmp[1].type == ACPI_TYPE_STRING ||
0174          tmp[1].type == ACPI_TYPE_BUFFER)) {
0175         /*
0176          * The second string element is optional even when
0177          * this _DSM is implemented; when not implemented,
0178          * this entry must return a null string.
0179          */
0180         if (attr == ACPI_ATTR_INDEX_SHOW) {
0181             len = sysfs_emit(buf, "%llu\n", tmp->integer.value);
0182         } else if (attr == ACPI_ATTR_LABEL_SHOW) {
0183             if (tmp[1].type == ACPI_TYPE_STRING)
0184                 len = sysfs_emit(buf, "%s\n",
0185                          tmp[1].string.pointer);
0186             else if (tmp[1].type == ACPI_TYPE_BUFFER)
0187                 len = dsm_label_utf16s_to_utf8s(tmp + 1, buf);
0188         }
0189     }
0190
0191     ACPI_FREE(obj);
0192
0193     return len > 0 ? len : -1;
0194 }
0195
0196 static ssize_t label_show(struct device *dev, struct device_attribute *attr,
0197               char *buf)
0198 {
0199     return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW);
0200 }
0201 static DEVICE_ATTR_RO(label);
0202
0203 static ssize_t acpi_index_show(struct device *dev,
0204                   struct device_attribute *attr, char *buf)
0205 {
0206     return dsm_get_label(dev, buf, ACPI_ATTR_INDEX_SHOW);
0207 }
0208 static DEVICE_ATTR_RO(acpi_index);
0209
0210 static struct attribute *acpi_attrs[] = {
0211     &dev_attr_label.attr,
0212     &dev_attr_acpi_index.attr,
0213     NULL,
0214 };
0215
0216 static umode_t acpi_attr_is_visible(struct kobject *kobj, struct attribute *a,
0217                     int n)
0218 {
0219     struct device *dev = kobj_to_dev(kobj);
0220
0221     if (!device_has_acpi_name(dev))
0222         return 0;
0223
0224     return a->mode;
0225 }
0226
0227 const struct attribute_group pci_dev_acpi_attr_group = {
0228     .attrs = acpi_attrs,
0229     .is_visible = acpi_attr_is_visible,
0230 };
0231 #endif