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- // SPDX-License-Identifier: GPL-2.0
- /*
- * Export the firmware instance and label associated with a PCI device to
- * sysfs
- *
- * Copyright (C) 2010 Dell Inc.
- * by Narendra K <[email protected]>,
- * Jordan Hargrave <[email protected]>
- *
- * PCI Firmware Specification Revision 3.1 section 4.6.7 (DSM for Naming a
- * PCI or PCI Express Device Under Operating Systems) defines an instance
- * number and string name. This code retrieves them and exports them to sysfs.
- * If the system firmware does not provide the ACPI _DSM (Device Specific
- * Method), then the SMBIOS type 41 instance number and string is exported to
- * sysfs.
- *
- * SMBIOS defines type 41 for onboard pci devices. This code retrieves
- * the instance number and string from the type 41 record and exports
- * it to sysfs.
- *
- * Please see https://linux.dell.com/files/biosdevname/ for more
- * information.
- */
- #include <linux/dmi.h>
- #include <linux/sysfs.h>
- #include <linux/pci.h>
- #include <linux/pci_ids.h>
- #include <linux/module.h>
- #include <linux/device.h>
- #include <linux/nls.h>
- #include <linux/acpi.h>
- #include <linux/pci-acpi.h>
- #include "pci.h"
- static bool device_has_acpi_name(struct device *dev)
- {
- #ifdef CONFIG_ACPI
- acpi_handle handle = ACPI_HANDLE(dev);
- if (!handle)
- return false;
- return acpi_check_dsm(handle, &pci_acpi_dsm_guid, 0x2,
- 1 << DSM_PCI_DEVICE_NAME);
- #else
- return false;
- #endif
- }
- #ifdef CONFIG_DMI
- enum smbios_attr_enum {
- SMBIOS_ATTR_NONE = 0,
- SMBIOS_ATTR_LABEL_SHOW,
- SMBIOS_ATTR_INSTANCE_SHOW,
- };
- static size_t find_smbios_instance_string(struct pci_dev *pdev, char *buf,
- enum smbios_attr_enum attribute)
- {
- const struct dmi_device *dmi;
- struct dmi_dev_onboard *donboard;
- int domain_nr = pci_domain_nr(pdev->bus);
- int bus = pdev->bus->number;
- int devfn = pdev->devfn;
- dmi = NULL;
- while ((dmi = dmi_find_device(DMI_DEV_TYPE_DEV_ONBOARD,
- NULL, dmi)) != NULL) {
- donboard = dmi->device_data;
- if (donboard && donboard->segment == domain_nr &&
- donboard->bus == bus &&
- donboard->devfn == devfn) {
- if (buf) {
- if (attribute == SMBIOS_ATTR_INSTANCE_SHOW)
- return sysfs_emit(buf, "%d\n",
- donboard->instance);
- else if (attribute == SMBIOS_ATTR_LABEL_SHOW)
- return sysfs_emit(buf, "%s\n",
- dmi->name);
- }
- return strlen(dmi->name);
- }
- }
- return 0;
- }
- static ssize_t smbios_label_show(struct device *dev,
- struct device_attribute *attr, char *buf)
- {
- struct pci_dev *pdev = to_pci_dev(dev);
- return find_smbios_instance_string(pdev, buf,
- SMBIOS_ATTR_LABEL_SHOW);
- }
- static struct device_attribute dev_attr_smbios_label = __ATTR(label, 0444,
- smbios_label_show, NULL);
- static ssize_t index_show(struct device *dev, struct device_attribute *attr,
- char *buf)
- {
- struct pci_dev *pdev = to_pci_dev(dev);
- return find_smbios_instance_string(pdev, buf,
- SMBIOS_ATTR_INSTANCE_SHOW);
- }
- static DEVICE_ATTR_RO(index);
- static struct attribute *smbios_attrs[] = {
- &dev_attr_smbios_label.attr,
- &dev_attr_index.attr,
- NULL,
- };
- static umode_t smbios_attr_is_visible(struct kobject *kobj, struct attribute *a,
- int n)
- {
- struct device *dev = kobj_to_dev(kobj);
- struct pci_dev *pdev = to_pci_dev(dev);
- if (device_has_acpi_name(dev))
- return 0;
- if (!find_smbios_instance_string(pdev, NULL, SMBIOS_ATTR_NONE))
- return 0;
- return a->mode;
- }
- const struct attribute_group pci_dev_smbios_attr_group = {
- .attrs = smbios_attrs,
- .is_visible = smbios_attr_is_visible,
- };
- #endif
- #ifdef CONFIG_ACPI
- enum acpi_attr_enum {
- ACPI_ATTR_LABEL_SHOW,
- ACPI_ATTR_INDEX_SHOW,
- };
- static int dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf)
- {
- int len;
- len = utf16s_to_utf8s((const wchar_t *)obj->buffer.pointer,
- obj->buffer.length,
- UTF16_LITTLE_ENDIAN,
- buf, PAGE_SIZE - 1);
- buf[len++] = '\n';
- return len;
- }
- static int dsm_get_label(struct device *dev, char *buf,
- enum acpi_attr_enum attr)
- {
- acpi_handle handle = ACPI_HANDLE(dev);
- union acpi_object *obj, *tmp;
- int len = 0;
- if (!handle)
- return -1;
- obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 0x2,
- DSM_PCI_DEVICE_NAME, NULL);
- if (!obj)
- return -1;
- tmp = obj->package.elements;
- if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 2 &&
- tmp[0].type == ACPI_TYPE_INTEGER &&
- (tmp[1].type == ACPI_TYPE_STRING ||
- tmp[1].type == ACPI_TYPE_BUFFER)) {
- /*
- * The second string element is optional even when
- * this _DSM is implemented; when not implemented,
- * this entry must return a null string.
- */
- if (attr == ACPI_ATTR_INDEX_SHOW) {
- len = sysfs_emit(buf, "%llu\n", tmp->integer.value);
- } else if (attr == ACPI_ATTR_LABEL_SHOW) {
- if (tmp[1].type == ACPI_TYPE_STRING)
- len = sysfs_emit(buf, "%s\n",
- tmp[1].string.pointer);
- else if (tmp[1].type == ACPI_TYPE_BUFFER)
- len = dsm_label_utf16s_to_utf8s(tmp + 1, buf);
- }
- }
- ACPI_FREE(obj);
- return len > 0 ? len : -1;
- }
- static ssize_t label_show(struct device *dev, struct device_attribute *attr,
- char *buf)
- {
- return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW);
- }
- static DEVICE_ATTR_RO(label);
- static ssize_t acpi_index_show(struct device *dev,
- struct device_attribute *attr, char *buf)
- {
- return dsm_get_label(dev, buf, ACPI_ATTR_INDEX_SHOW);
- }
- static DEVICE_ATTR_RO(acpi_index);
- static struct attribute *acpi_attrs[] = {
- &dev_attr_label.attr,
- &dev_attr_acpi_index.attr,
- NULL,
- };
- static umode_t acpi_attr_is_visible(struct kobject *kobj, struct attribute *a,
- int n)
- {
- struct device *dev = kobj_to_dev(kobj);
- if (!device_has_acpi_name(dev))
- return 0;
- return a->mode;
- }
- const struct attribute_group pci_dev_acpi_attr_group = {
- .attrs = acpi_attrs,
- .is_visible = acpi_attr_is_visible,
- };
- #endif
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