drivers/pci/pci-label.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Export the firmware instance and label associated with a PCI device to
   4  * sysfs
   5  *
   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 a
  11  * PCI or PCI Express Device Under Operating Systems) defines an instance
  12  * 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 Specific
  14  * Method), then the SMBIOS type 41 instance number and string is exported to
  15  * sysfs.
  16  *
  17  * SMBIOS defines type 41 for onboard pci devices. This code retrieves
  18  * the instance number and string from the type 41 record and exports
  19  * it to sysfs.
  20  *
  21  * Please see https://linux.dell.com/files/biosdevname/ for more
  22  * 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
  36 static bool device_has_acpi_name(struct device *dev)
  37 {
  38 #ifdef CONFIG_ACPI
  39         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 #else
  47         return false;
  48 #endif
  49 }
  50
  51 #ifdef CONFIG_DMI
  52 enum smbios_attr_enum {
  53         SMBIOS_ATTR_NONE = 0,
  54         SMBIOS_ATTR_LABEL_SHOW,
  55         SMBIOS_ATTR_INSTANCE_SHOW,
  56 };
  57
  58 static 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 scnprintf(buf, PAGE_SIZE,
  77                                                          "%d\n",
  78                                                          donboard->instance);
  79                                 else if (attribute == SMBIOS_ATTR_LABEL_SHOW)
  80                                         return scnprintf(buf, PAGE_SIZE,
  81                                                          "%s\n",
  82                                                          dmi->name);
  83                         }
  84                         return strlen(dmi->name);
  85                 }
  86         }
  87         return 0;
  88 }
  89
  90 static umode_t smbios_attr_is_visible(struct kobject *kobj, struct attribute *a,
  91                                       int n)
  92 {
  93         struct device *dev = kobj_to_dev(kobj);
  94         struct pci_dev *pdev = to_pci_dev(dev);
  95
  96         if (device_has_acpi_name(dev))
  97                 return 0;
  98
  99         if (!find_smbios_instance_string(pdev, NULL, SMBIOS_ATTR_NONE))
 100                 return 0;
 101
 102         return a->mode;
 103 }
 104
 105 static ssize_t smbios_label_show(struct device *dev,
 106                                  struct device_attribute *attr, char *buf)
 107 {
 108         struct pci_dev *pdev = to_pci_dev(dev);
 109
 110         return find_smbios_instance_string(pdev, buf,
 111                                            SMBIOS_ATTR_LABEL_SHOW);
 112 }
 113 static struct device_attribute dev_attr_smbios_label = __ATTR(label, 0444,
 114                                                     smbios_label_show, NULL);
 115
 116 static ssize_t index_show(struct device *dev, struct device_attribute *attr,
 117                           char *buf)
 118 {
 119         struct pci_dev *pdev = to_pci_dev(dev);
 120
 121         return find_smbios_instance_string(pdev, buf,
 122                                            SMBIOS_ATTR_INSTANCE_SHOW);
 123 }
 124 static DEVICE_ATTR_RO(index);
 125
 126 static struct attribute *smbios_attrs[] = {
 127         &dev_attr_smbios_label.attr,
 128         &dev_attr_index.attr,
 129         NULL,
 130 };
 131
 132 const struct attribute_group pci_dev_smbios_attr_group = {
 133         .attrs = smbios_attrs,
 134         .is_visible = smbios_attr_is_visible,
 135 };
 136 #endif
 137
 138 #ifdef CONFIG_ACPI
 139 enum acpi_attr_enum {
 140         ACPI_ATTR_LABEL_SHOW,
 141         ACPI_ATTR_INDEX_SHOW,
 142 };
 143
 144 static void dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf)
 145 {
 146         int len;
 147         len = utf16s_to_utf8s((const wchar_t *)obj->buffer.pointer,
 148                               obj->buffer.length,
 149                               UTF16_LITTLE_ENDIAN,
 150                               buf, PAGE_SIZE);
 151         buf[len] = '\n';
 152 }
 153
 154 static int dsm_get_label(struct device *dev, char *buf,
 155                          enum acpi_attr_enum attr)
 156 {
 157         acpi_handle handle = ACPI_HANDLE(dev);
 158         union acpi_object *obj, *tmp;
 159         int len = -1;
 160
 161         if (!handle)
 162                 return -1;
 163
 164         obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 0x2,
 165                                 DSM_PCI_DEVICE_NAME, NULL);
 166         if (!obj)
 167                 return -1;
 168
 169         tmp = obj->package.elements;
 170         if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 2 &&
 171             tmp[0].type == ACPI_TYPE_INTEGER &&
 172             (tmp[1].type == ACPI_TYPE_STRING ||
 173              tmp[1].type == ACPI_TYPE_BUFFER)) {
 174                 /*
 175                  * The second string element is optional even when
 176                  * this _DSM is implemented; when not implemented,
 177                  * this entry must return a null string.
 178                  */
 179                 if (attr == ACPI_ATTR_INDEX_SHOW) {
 180                         scnprintf(buf, PAGE_SIZE, "%llu\n", tmp->integer.value);
 181                 } else if (attr == ACPI_ATTR_LABEL_SHOW) {
 182                         if (tmp[1].type == ACPI_TYPE_STRING)
 183                                 scnprintf(buf, PAGE_SIZE, "%s\n",
 184                                           tmp[1].string.pointer);
 185                         else if (tmp[1].type == ACPI_TYPE_BUFFER)
 186                                 dsm_label_utf16s_to_utf8s(tmp + 1, buf);
 187                 }
 188                 len = strlen(buf) > 0 ? strlen(buf) : -1;
 189         }
 190
 191         ACPI_FREE(obj);
 192
 193         return len;
 194 }
 195
 196 static umode_t acpi_attr_is_visible(struct kobject *kobj, struct attribute *a,
 197                                     int n)
 198 {
 199         struct device *dev = kobj_to_dev(kobj);
 200
 201         if (!device_has_acpi_name(dev))
 202                 return 0;
 203
 204         return a->mode;
 205 }
 206
 207 static ssize_t label_show(struct device *dev, struct device_attribute *attr,
 208                           char *buf)
 209 {
 210         return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW);
 211 }
 212 static DEVICE_ATTR_RO(label);
 213
 214 static ssize_t acpi_index_show(struct device *dev,
 215                               struct device_attribute *attr, char *buf)
 216 {
 217         return dsm_get_label(dev, buf, ACPI_ATTR_INDEX_SHOW);
 218 }
 219 static DEVICE_ATTR_RO(acpi_index);
 220
 221 static struct attribute *acpi_attrs[] = {
 222         &dev_attr_label.attr,
 223         &dev_attr_acpi_index.attr,
 224         NULL,
 225 };
 226
 227 const struct attribute_group pci_dev_acpi_attr_group = {
 228         .attrs = acpi_attrs,
 229         .is_visible = acpi_attr_is_visible,
 230 };
 231 #endif