linux/drivers/pci/pci-label.c
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   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
  37enum smbios_attr_enum {
  38        SMBIOS_ATTR_NONE = 0,
  39        SMBIOS_ATTR_LABEL_SHOW,
  40        SMBIOS_ATTR_INSTANCE_SHOW,
  41};
  42
  43static 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
  79static 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
  92static 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
 102static 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
 112static struct device_attribute smbios_attr_label = {
 113        .attr = {.name = "label", .mode = 0444},
 114        .show = smbioslabel_show,
 115};
 116
 117static struct device_attribute smbios_attr_instance = {
 118        .attr = {.name = "index", .mode = 0444},
 119        .show = smbiosinstance_show,
 120};
 121
 122static struct attribute *smbios_attributes[] = {
 123        &smbios_attr_label.attr,
 124        &smbios_attr_instance.attr,
 125        NULL,
 126};
 127
 128static const struct attribute_group smbios_attr_group = {
 129        .attrs = smbios_attributes,
 130        .is_visible = smbios_instance_string_exist,
 131};
 132
 133static int pci_create_smbiosname_file(struct pci_dev *pdev)
 134{
 135        return sysfs_create_group(&pdev->dev.kobj, &smbios_attr_group);
 136}
 137
 138static void pci_remove_smbiosname_file(struct pci_dev *pdev)
 139{
 140        sysfs_remove_group(&pdev->dev.kobj, &smbios_attr_group);
 141}
 142#else
 143static inline int pci_create_smbiosname_file(struct pci_dev *pdev)
 144{
 145        return -1;
 146}
 147
 148static inline void pci_remove_smbiosname_file(struct pci_dev *pdev)
 149{
 150}
 151#endif
 152
 153#ifdef CONFIG_ACPI
 154enum acpi_attr_enum {
 155        ACPI_ATTR_LABEL_SHOW,
 156        ACPI_ATTR_INDEX_SHOW,
 157};
 158
 159static 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
 169static 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
 212static 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
 224static 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
 237static 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
 243static 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
 249static struct device_attribute acpi_attr_label = {
 250        .attr = {.name = "label", .mode = 0444},
 251        .show = acpilabel_show,
 252};
 253
 254static struct device_attribute acpi_attr_index = {
 255        .attr = {.name = "acpi_index", .mode = 0444},
 256        .show = acpiindex_show,
 257};
 258
 259static struct attribute *acpi_attributes[] = {
 260        &acpi_attr_label.attr,
 261        &acpi_attr_index.attr,
 262        NULL,
 263};
 264
 265static const struct attribute_group acpi_attr_group = {
 266        .attrs = acpi_attributes,
 267        .is_visible = acpi_index_string_exist,
 268};
 269
 270static 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
 275static 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
 281static inline int pci_create_acpi_index_label_files(struct pci_dev *pdev)
 282{
 283        return -1;
 284}
 285
 286static inline int pci_remove_acpi_index_label_files(struct pci_dev *pdev)
 287{
 288        return -1;
 289}
 290
 291static inline bool device_has_dsm(struct device *dev)
 292{
 293        return false;
 294}
 295#endif
 296
 297void 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
 305void 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}
 312