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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 <Narendra_K@dell.com>,
* Jordan Hargrave <Jordan_Hargrave@dell.com>
*
* 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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