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 http://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 #ifdef CONFIG_DMI
  37 enum smbios_attr_enum {
  38         SMBIOS_ATTR_NONE = 0,
  39         SMBIOS_ATTR_LABEL_SHOW,
  40         SMBIOS_ATTR_INSTANCE_SHOW,
  41 };
  42
  43 static size_t find_smbios_instance_string(struct pci_dev *pdev, char *buf,
  44                                           enum smbios_attr_enum attribute)
  45 {
  46         const struct dmi_device *dmi;
  47         struct dmi_dev_onboard *donboard;
  48         int domain_nr;
  49         int bus;
  50         int devfn;
  51
  52         domain_nr = pci_domain_nr(pdev->bus);
  53         bus = pdev->bus->number;
  54         devfn = pdev->devfn;
  55
  56         dmi = NULL;
  57         while ((dmi = dmi_find_device(DMI_DEV_TYPE_DEV_ONBOARD,
  58                                       NULL, dmi)) != NULL) {
  59                 donboard = dmi->device_data;
  60                 if (donboard && donboard->segment == domain_nr &&
  61                                 donboard->bus == bus &&
  62                                 donboard->devfn == devfn) {
  63                         if (buf) {
  64                                 if (attribute == SMBIOS_ATTR_INSTANCE_SHOW)
  65                                         return scnprintf(buf, PAGE_SIZE,
  66                                                          "%d\n",
  67                                                          donboard->instance);
  68                                 else if (attribute == SMBIOS_ATTR_LABEL_SHOW)
  69                                         return scnprintf(buf, PAGE_SIZE,
  70                                                          "%s\n",
  71                                                          dmi->name);
  72                         }
  73                         return strlen(dmi->name);
  74                 }
  75         }
  76         return 0;
  77 }
  78
  79 static umode_t smbios_instance_string_exist(struct kobject *kobj,
  80                                             struct attribute *attr, int n)
  81 {
  82         struct device *dev;
  83         struct pci_dev *pdev;
  84
  85         dev = kobj_to_dev(kobj);
  86         pdev = to_pci_dev(dev);
  87
  88         return find_smbios_instance_string(pdev, NULL, SMBIOS_ATTR_NONE) ?
  89                                            S_IRUGO : 0;
  90 }
  91
  92 static ssize_t smbioslabel_show(struct device *dev,
  93                                 struct device_attribute *attr, char *buf)
  94 {
  95         struct pci_dev *pdev;
  96         pdev = to_pci_dev(dev);
  97
  98         return find_smbios_instance_string(pdev, buf,
  99                                            SMBIOS_ATTR_LABEL_SHOW);
 100 }
 101
 102 static ssize_t smbiosinstance_show(struct device *dev,
 103                                    struct device_attribute *attr, char *buf)
 104 {
 105         struct pci_dev *pdev;
 106         pdev = to_pci_dev(dev);
 107
 108         return find_smbios_instance_string(pdev, buf,
 109                                            SMBIOS_ATTR_INSTANCE_SHOW);
 110 }
 111
 112 static struct device_attribute smbios_attr_label = {
 113         .attr = {.name = "label", .mode = 0444},
 114         .show = smbioslabel_show,
 115 };
 116
 117 static struct device_attribute smbios_attr_instance = {
 118         .attr = {.name = "index", .mode = 0444},
 119         .show = smbiosinstance_show,
 120 };
 121
 122 static struct attribute *smbios_attributes[] = {
 123         &smbios_attr_label.attr,
 124         &smbios_attr_instance.attr,
 125         NULL,
 126 };
 127
 128 static const struct attribute_group smbios_attr_group = {
 129         .attrs = smbios_attributes,
 130         .is_visible = smbios_instance_string_exist,
 131 };
 132
 133 static int pci_create_smbiosname_file(struct pci_dev *pdev)
 134 {
 135         return sysfs_create_group(&pdev->dev.kobj, &smbios_attr_group);
 136 }
 137
 138 static void pci_remove_smbiosname_file(struct pci_dev *pdev)
 139 {
 140         sysfs_remove_group(&pdev->dev.kobj, &smbios_attr_group);
 141 }
 142 #else
 143 static inline int pci_create_smbiosname_file(struct pci_dev *pdev)
 144 {
 145         return -1;
 146 }
 147
 148 static inline void pci_remove_smbiosname_file(struct pci_dev *pdev)
 149 {
 150 }
 151 #endif
 152
 153 #ifdef CONFIG_ACPI
 154 enum acpi_attr_enum {
 155         ACPI_ATTR_LABEL_SHOW,
 156         ACPI_ATTR_INDEX_SHOW,
 157 };
 158
 159 static void dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf)
 160 {
 161         int len;
 162         len = utf16s_to_utf8s((const wchar_t *)obj->buffer.pointer,
 163                               obj->buffer.length,
 164                               UTF16_LITTLE_ENDIAN,
 165                               buf, PAGE_SIZE);
 166         buf[len] = '\n';
 167 }
 168
 169 static int dsm_get_label(struct device *dev, char *buf,
 170                          enum acpi_attr_enum attr)
 171 {
 172         acpi_handle handle;
 173         union acpi_object *obj, *tmp;
 174         int len = -1;
 175
 176         handle = ACPI_HANDLE(dev);
 177         if (!handle)
 178                 return -1;
 179
 180         obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 0x2,
 181                                 DEVICE_LABEL_DSM, NULL);
 182         if (!obj)
 183                 return -1;
 184
 185         tmp = obj->package.elements;
 186         if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 2 &&
 187             tmp[0].type == ACPI_TYPE_INTEGER &&
 188             (tmp[1].type == ACPI_TYPE_STRING ||
 189              tmp[1].type == ACPI_TYPE_BUFFER)) {
 190                 /*
 191                  * The second string element is optional even when
 192                  * this _DSM is implemented; when not implemented,
 193                  * this entry must return a null string.
 194                  */
 195                 if (attr == ACPI_ATTR_INDEX_SHOW) {
 196                         scnprintf(buf, PAGE_SIZE, "%llu\n", tmp->integer.value);
 197                 } else if (attr == ACPI_ATTR_LABEL_SHOW) {
 198                         if (tmp[1].type == ACPI_TYPE_STRING)
 199                                 scnprintf(buf, PAGE_SIZE, "%s\n",
 200                                           tmp[1].string.pointer);
 201                         else if (tmp[1].type == ACPI_TYPE_BUFFER)
 202                                 dsm_label_utf16s_to_utf8s(tmp + 1, buf);
 203                 }
 204                 len = strlen(buf) > 0 ? strlen(buf) : -1;
 205         }
 206
 207         ACPI_FREE(obj);
 208
 209         return len;
 210 }
 211
 212 static bool device_has_dsm(struct device *dev)
 213 {
 214         acpi_handle handle;
 215
 216         handle = ACPI_HANDLE(dev);
 217         if (!handle)
 218                 return false;
 219
 220         return !!acpi_check_dsm(handle, &pci_acpi_dsm_guid, 0x2,
 221                                 1 << DEVICE_LABEL_DSM);
 222 }
 223
 224 static umode_t acpi_index_string_exist(struct kobject *kobj,
 225                                        struct attribute *attr, int n)
 226 {
 227         struct device *dev;
 228
 229         dev = kobj_to_dev(kobj);
 230
 231         if (device_has_dsm(dev))
 232                 return S_IRUGO;
 233
 234         return 0;
 235 }
 236
 237 static ssize_t acpilabel_show(struct device *dev,
 238                               struct device_attribute *attr, char *buf)
 239 {
 240         return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW);
 241 }
 242
 243 static ssize_t acpiindex_show(struct device *dev,
 244                               struct device_attribute *attr, char *buf)
 245 {
 246         return dsm_get_label(dev, buf, ACPI_ATTR_INDEX_SHOW);
 247 }
 248
 249 static struct device_attribute acpi_attr_label = {
 250         .attr = {.name = "label", .mode = 0444},
 251         .show = acpilabel_show,
 252 };
 253
 254 static struct device_attribute acpi_attr_index = {
 255         .attr = {.name = "acpi_index", .mode = 0444},
 256         .show = acpiindex_show,
 257 };
 258
 259 static struct attribute *acpi_attributes[] = {
 260         &acpi_attr_label.attr,
 261         &acpi_attr_index.attr,
 262         NULL,
 263 };
 264
 265 static const struct attribute_group acpi_attr_group = {
 266         .attrs = acpi_attributes,
 267         .is_visible = acpi_index_string_exist,
 268 };
 269
 270 static int pci_create_acpi_index_label_files(struct pci_dev *pdev)
 271 {
 272         return sysfs_create_group(&pdev->dev.kobj, &acpi_attr_group);
 273 }
 274
 275 static int pci_remove_acpi_index_label_files(struct pci_dev *pdev)
 276 {
 277         sysfs_remove_group(&pdev->dev.kobj, &acpi_attr_group);
 278         return 0;
 279 }
 280 #else
 281 static inline int pci_create_acpi_index_label_files(struct pci_dev *pdev)
 282 {
 283         return -1;
 284 }
 285
 286 static inline int pci_remove_acpi_index_label_files(struct pci_dev *pdev)
 287 {
 288         return -1;
 289 }
 290
 291 static inline bool device_has_dsm(struct device *dev)
 292 {
 293         return false;
 294 }
 295 #endif
 296
 297 void pci_create_firmware_label_files(struct pci_dev *pdev)
 298 {
 299         if (device_has_dsm(&pdev->dev))
 300                 pci_create_acpi_index_label_files(pdev);
 301         else
 302                 pci_create_smbiosname_file(pdev);
 303 }
 304
 305 void pci_remove_firmware_label_files(struct pci_dev *pdev)
 306 {
 307         if (device_has_dsm(&pdev->dev))
 308                 pci_remove_acpi_index_label_files(pdev);
 309         else
 310                 pci_remove_smbiosname_file(pdev);
 311 }