text: // 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"
  
  #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;
  	int bus;
  	int devfn;
  
  	domain_nr = pci_domain_nr(pdev->bus);
  	bus = pdev->bus->number;
  	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 scnprintf(buf, PAGE_SIZE,
  							 "%d\n",
  							 donboard->instance);
  				else if (attribute == SMBIOS_ATTR_LABEL_SHOW)
  					return scnprintf(buf, PAGE_SIZE,
  							 "%s\n",
  							 dmi->name);
  			}
  			return strlen(dmi->name);
  		}
  	}
  	return 0;
  }
  
  static umode_t smbios_instance_string_exist(struct kobject *kobj,
  					    struct attribute *attr, int n)
  {
  	struct device *dev;
  	struct pci_dev *pdev;
  
  	dev = kobj_to_dev(kobj);
  	pdev = to_pci_dev(dev);
  
  	return find_smbios_instance_string(pdev, NULL, SMBIOS_ATTR_NONE) ?
  					   S_IRUGO : 0;
  }
  
  static ssize_t smbioslabel_show(struct device *dev,
  				struct device_attribute *attr, char *buf)
  {
  	struct pci_dev *pdev;
  	pdev = to_pci_dev(dev);
  
  	return find_smbios_instance_string(pdev, buf,
  					   SMBIOS_ATTR_LABEL_SHOW);
  }
  
  static ssize_t smbiosinstance_show(struct device *dev,
  				   struct device_attribute *attr, char *buf)
  {
  	struct pci_dev *pdev;
  	pdev = to_pci_dev(dev);
  
  	return find_smbios_instance_string(pdev, buf,
  					   SMBIOS_ATTR_INSTANCE_SHOW);
  }
  
  static struct device_attribute smbios_attr_label = {
  	.attr = {.name = "label", .mode = 0444},
  	.show = smbioslabel_show,
  };
  
  static struct device_attribute smbios_attr_instance = {
  	.attr = {.name = "index", .mode = 0444},
  	.show = smbiosinstance_show,
  };
  
  static struct attribute *smbios_attributes[] = {
  	&smbios_attr_label.attr,
  	&smbios_attr_instance.attr,
  	NULL,
  };
  
  static const struct attribute_group smbios_attr_group = {
  	.attrs = smbios_attributes,
  	.is_visible = smbios_instance_string_exist,
  };
  
  static int pci_create_smbiosname_file(struct pci_dev *pdev)
  {
  	return sysfs_create_group(&pdev->dev.kobj, &smbios_attr_group);
  }
  
  static void pci_remove_smbiosname_file(struct pci_dev *pdev)
  {
  	sysfs_remove_group(&pdev->dev.kobj, &smbios_attr_group);
  }
  #else
  static inline int pci_create_smbiosname_file(struct pci_dev *pdev)
  {
  	return -1;
  }
  
  static inline void pci_remove_smbiosname_file(struct pci_dev *pdev)
  {
  }
  #endif
  
  #ifdef CONFIG_ACPI
  enum acpi_attr_enum {
  	ACPI_ATTR_LABEL_SHOW,
  	ACPI_ATTR_INDEX_SHOW,
  };
  
  static void 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';
  }
  
  static int dsm_get_label(struct device *dev, char *buf,
  			 enum acpi_attr_enum attr)
  {
  	acpi_handle handle;
  	union acpi_object *obj, *tmp;
  	int len = -1;
  
  	handle = ACPI_HANDLE(dev);
  	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) {
  			scnprintf(buf, PAGE_SIZE, "%llu\n", tmp->integer.value);
  		} else if (attr == ACPI_ATTR_LABEL_SHOW) {
  			if (tmp[1].type == ACPI_TYPE_STRING)
  				scnprintf(buf, PAGE_SIZE, "%s\n",
  					  tmp[1].string.pointer);
  			else if (tmp[1].type == ACPI_TYPE_BUFFER)
  				dsm_label_utf16s_to_utf8s(tmp + 1, buf);
  		}
  		len = strlen(buf) > 0 ? strlen(buf) : -1;
  	}
  
  	ACPI_FREE(obj);
  
  	return len;
  }
  
  static bool device_has_dsm(struct device *dev)
  {
  	acpi_handle handle;
  
  	handle = ACPI_HANDLE(dev);
  	if (!handle)
  		return false;
  
  	return !!acpi_check_dsm(handle, &pci_acpi_dsm_guid, 0x2,
  				1 << DSM_PCI_DEVICE_NAME);
  }
  
  static umode_t acpi_index_string_exist(struct kobject *kobj,
  				       struct attribute *attr, int n)
  {
  	struct device *dev;
  
  	dev = kobj_to_dev(kobj);
  
  	if (device_has_dsm(dev))
  		return S_IRUGO;
  
  	return 0;
  }
  
  static ssize_t acpilabel_show(struct device *dev,
  			      struct device_attribute *attr, char *buf)
  {
  	return dsm_get_label(dev, buf, ACPI_ATTR_LABEL_SHOW);
  }
  
  static ssize_t acpiindex_show(struct device *dev,
  			      struct device_attribute *attr, char *buf)
  {
  	return dsm_get_label(dev, buf, ACPI_ATTR_INDEX_SHOW);
  }
  
  static struct device_attribute acpi_attr_label = {
  	.attr = {.name = "label", .mode = 0444},
  	.show = acpilabel_show,
  };
  
  static struct device_attribute acpi_attr_index = {
  	.attr = {.name = "acpi_index", .mode = 0444},
  	.show = acpiindex_show,
  };
  
  static struct attribute *acpi_attributes[] = {
  	&acpi_attr_label.attr,
  	&acpi_attr_index.attr,
  	NULL,
  };
  
  static const struct attribute_group acpi_attr_group = {
  	.attrs = acpi_attributes,
  	.is_visible = acpi_index_string_exist,
  };
  
  static int pci_create_acpi_index_label_files(struct pci_dev *pdev)
  {
  	return sysfs_create_group(&pdev->dev.kobj, &acpi_attr_group);
  }
  
  static int pci_remove_acpi_index_label_files(struct pci_dev *pdev)
  {
  	sysfs_remove_group(&pdev->dev.kobj, &acpi_attr_group);
  	return 0;
  }
  #else
  static inline int pci_create_acpi_index_label_files(struct pci_dev *pdev)
  {
  	return -1;
  }
  
  static inline int pci_remove_acpi_index_label_files(struct pci_dev *pdev)
  {
  	return -1;
  }
  
  static inline bool device_has_dsm(struct device *dev)
  {
  	return false;
  }
  #endif
  
  void pci_create_firmware_label_files(struct pci_dev *pdev)
  {
  	if (device_has_dsm(&pdev->dev))
  		pci_create_acpi_index_label_files(pdev);
  	else
  		pci_create_smbiosname_file(pdev);
  }
  
  void pci_remove_firmware_label_files(struct pci_dev *pdev)
  {
  	if (device_has_dsm(&pdev->dev))
  		pci_remove_acpi_index_label_files(pdev);
  	else
  		pci_remove_smbiosname_file(pdev);
  }
  