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![Krzysztof Wilczyński](/assets/img/avatar_default.png)
The sysfs_emit() and sysfs_emit_at() functions were introduced to make
it less ambiguous which function is preferred when writing to the output
buffer in a device attribute's "show" callback [1].
Convert the PCI sysfs object "show" functions from sprintf(), snprintf()
and scnprintf() to sysfs_emit() and sysfs_emit_at() accordingly, as the
latter is aware of the PAGE_SIZE buffer and correctly returns the number
of bytes written into the buffer.
No functional change intended.
[1] Documentation/filesystems/sysfs.rst
Related commit: ad025f8e46
("PCI/sysfs: Use sysfs_emit() and
sysfs_emit_at() in "show" functions").
Link: https://lore.kernel.org/r/20210603000112.703037-2-kw@linux.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
231 lines
5.6 KiB
C
231 lines
5.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Export the firmware instance and label associated with a PCI device to
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* sysfs
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*
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* Copyright (C) 2010 Dell Inc.
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* by Narendra K <Narendra_K@dell.com>,
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* Jordan Hargrave <Jordan_Hargrave@dell.com>
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*
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* PCI Firmware Specification Revision 3.1 section 4.6.7 (DSM for Naming a
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* PCI or PCI Express Device Under Operating Systems) defines an instance
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* number and string name. This code retrieves them and exports them to sysfs.
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* If the system firmware does not provide the ACPI _DSM (Device Specific
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* Method), then the SMBIOS type 41 instance number and string is exported to
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* sysfs.
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*
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* SMBIOS defines type 41 for onboard pci devices. This code retrieves
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* the instance number and string from the type 41 record and exports
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* it to sysfs.
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*
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* Please see https://linux.dell.com/files/biosdevname/ for more
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* information.
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*/
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#include <linux/dmi.h>
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#include <linux/sysfs.h>
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#include <linux/pci.h>
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#include <linux/pci_ids.h>
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#include <linux/module.h>
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#include <linux/device.h>
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#include <linux/nls.h>
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#include <linux/acpi.h>
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#include <linux/pci-acpi.h>
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#include "pci.h"
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static bool device_has_acpi_name(struct device *dev)
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{
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#ifdef CONFIG_ACPI
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acpi_handle handle = ACPI_HANDLE(dev);
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if (!handle)
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return false;
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return acpi_check_dsm(handle, &pci_acpi_dsm_guid, 0x2,
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1 << DSM_PCI_DEVICE_NAME);
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#else
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return false;
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#endif
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}
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#ifdef CONFIG_DMI
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enum smbios_attr_enum {
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SMBIOS_ATTR_NONE = 0,
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SMBIOS_ATTR_LABEL_SHOW,
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SMBIOS_ATTR_INSTANCE_SHOW,
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};
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static size_t find_smbios_instance_string(struct pci_dev *pdev, char *buf,
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enum smbios_attr_enum attribute)
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{
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const struct dmi_device *dmi;
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struct dmi_dev_onboard *donboard;
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int domain_nr = pci_domain_nr(pdev->bus);
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int bus = pdev->bus->number;
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int devfn = pdev->devfn;
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dmi = NULL;
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while ((dmi = dmi_find_device(DMI_DEV_TYPE_DEV_ONBOARD,
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NULL, dmi)) != NULL) {
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donboard = dmi->device_data;
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if (donboard && donboard->segment == domain_nr &&
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donboard->bus == bus &&
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donboard->devfn == devfn) {
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if (buf) {
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if (attribute == SMBIOS_ATTR_INSTANCE_SHOW)
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return sysfs_emit(buf, "%d\n",
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donboard->instance);
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else if (attribute == SMBIOS_ATTR_LABEL_SHOW)
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return sysfs_emit(buf, "%s\n",
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dmi->name);
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}
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return strlen(dmi->name);
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}
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}
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return 0;
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}
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static ssize_t smbios_label_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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struct pci_dev *pdev = to_pci_dev(dev);
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return find_smbios_instance_string(pdev, buf,
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SMBIOS_ATTR_LABEL_SHOW);
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}
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static struct device_attribute dev_attr_smbios_label = __ATTR(label, 0444,
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smbios_label_show, NULL);
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static ssize_t index_show(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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struct pci_dev *pdev = to_pci_dev(dev);
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return find_smbios_instance_string(pdev, buf,
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SMBIOS_ATTR_INSTANCE_SHOW);
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}
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static DEVICE_ATTR_RO(index);
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static struct attribute *smbios_attrs[] = {
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&dev_attr_smbios_label.attr,
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&dev_attr_index.attr,
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NULL,
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};
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static umode_t smbios_attr_is_visible(struct kobject *kobj, struct attribute *a,
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int n)
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{
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struct device *dev = kobj_to_dev(kobj);
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struct pci_dev *pdev = to_pci_dev(dev);
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if (device_has_acpi_name(dev))
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return 0;
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if (!find_smbios_instance_string(pdev, NULL, SMBIOS_ATTR_NONE))
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return 0;
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return a->mode;
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}
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const struct attribute_group pci_dev_smbios_attr_group = {
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.attrs = smbios_attrs,
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.is_visible = smbios_attr_is_visible,
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};
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#endif
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#ifdef CONFIG_ACPI
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enum acpi_attr_enum {
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ACPI_ATTR_LABEL_SHOW,
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ACPI_ATTR_INDEX_SHOW,
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};
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static int dsm_label_utf16s_to_utf8s(union acpi_object *obj, char *buf)
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{
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int len;
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len = utf16s_to_utf8s((const wchar_t *)obj->buffer.pointer,
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obj->buffer.length,
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UTF16_LITTLE_ENDIAN,
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buf, PAGE_SIZE - 1);
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buf[len++] = '\n';
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return len;
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}
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static int dsm_get_label(struct device *dev, char *buf,
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enum acpi_attr_enum attr)
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{
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acpi_handle handle = ACPI_HANDLE(dev);
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union acpi_object *obj, *tmp;
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int len = 0;
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if (!handle)
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return -1;
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obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 0x2,
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DSM_PCI_DEVICE_NAME, NULL);
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if (!obj)
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return -1;
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tmp = obj->package.elements;
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if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 2 &&
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tmp[0].type == ACPI_TYPE_INTEGER &&
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(tmp[1].type == ACPI_TYPE_STRING ||
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tmp[1].type == ACPI_TYPE_BUFFER)) {
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/*
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* The second string element is optional even when
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* this _DSM is implemented; when not implemented,
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* this entry must return a null string.
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*/
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if (attr == ACPI_ATTR_INDEX_SHOW) {
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len = sysfs_emit(buf, "%llu\n", tmp->integer.value);
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} else if (attr == ACPI_ATTR_LABEL_SHOW) {
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if (tmp[1].type == ACPI_TYPE_STRING)
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len = sysfs_emit(buf, "%s\n",
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tmp[1].string.pointer);
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else if (tmp[1].type == ACPI_TYPE_BUFFER)
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len = dsm_label_utf16s_to_utf8s(tmp + 1, buf);
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}
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}
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ACPI_FREE(obj);
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return len > 0 ? len : -1;
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}
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static ssize_t label_show(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW);
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}
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static DEVICE_ATTR_RO(label);
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static ssize_t acpi_index_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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return dsm_get_label(dev, buf, ACPI_ATTR_INDEX_SHOW);
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}
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static DEVICE_ATTR_RO(acpi_index);
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static struct attribute *acpi_attrs[] = {
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&dev_attr_label.attr,
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&dev_attr_acpi_index.attr,
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NULL,
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};
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static umode_t acpi_attr_is_visible(struct kobject *kobj, struct attribute *a,
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int n)
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{
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struct device *dev = kobj_to_dev(kobj);
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if (!device_has_acpi_name(dev))
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return 0;
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return a->mode;
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}
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const struct attribute_group pci_dev_acpi_attr_group = {
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.attrs = acpi_attrs,
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.is_visible = acpi_attr_is_visible,
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};
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#endif
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