/*
   * Purpose: 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 http://linux.dell.com/wiki/index.php/Oss/libnetdevname 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"
  
  #define	DEVICE_LABEL_DSM	0x07
  
  #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 bus;
  	int devfn;
  
  	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->bus == bus &&
  					donboard->devfn == devfn) {
  			if (buf) {
  				if (attribute == SMBIOS_ATTR_INSTANCE_SHOW)
  					return scnprintf(buf, PAGE_SIZE,
  							 "%d
  ",
  							 donboard->instance);
  				else if (attribute == SMBIOS_ATTR_LABEL_SHOW)
  					return scnprintf(buf, PAGE_SIZE,
  							 "%s
  ",
  							 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 = container_of(kobj, struct device, 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 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
  static const char device_label_dsm_uuid[] = {
  	0xD0, 0x37, 0xC9, 0xE5, 0x53, 0x35, 0x7A, 0x4D,
  	0x91, 0x17, 0xEA, 0x4D, 0x19, 0xC3, 0x43, 0x4D
  };
  
  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);
  	buf[len] = '
  ';
  }
  
  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, device_label_dsm_uuid, 0x2,
  				DEVICE_LABEL_DSM, 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
  ", tmp->integer.value);
  		} else if (attr == ACPI_ATTR_LABEL_SHOW) {
  			if (tmp[1].type == ACPI_TYPE_STRING)
  				scnprintf(buf, PAGE_SIZE, "%s
  ",
  					  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, device_label_dsm_uuid, 0x2,
  				1 << DEVICE_LABEL_DSM);
  }
  
  static umode_t
  acpi_index_string_exist(struct kobject *kobj, struct attribute *attr, int n)
  {
  	struct device *dev;
  
  	dev = container_of(kobj, struct device, 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 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);
  }