/*
   * EFI Variables - efivars.c
   *
   * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
   * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
   *
   * This code takes all variables accessible from EFI runtime and
   *  exports them via sysfs
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License as published by
   *  the Free Software Foundation; either version 2 of the License, or
   *  (at your option) any later version.
   *
   *  This program is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *  GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *  along with this program; if not, write to the Free Software
   *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   *
   * Changelog:
   *
   *  17 May 2004 - Matt Domsch <Matt_Domsch@dell.com>
   *   remove check for efi_enabled in exit
   *   add MODULE_VERSION
   *
   *  26 Apr 2004 - Matt Domsch <Matt_Domsch@dell.com>
   *   minor bug fixes
   *
   *  21 Apr 2004 - Matt Tolentino <matthew.e.tolentino@intel.com)
   *   converted driver to export variable information via sysfs
   *   and moved to drivers/firmware directory
   *   bumped revision number to v0.07 to reflect conversion & move
   *
   *  10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>
   *   fix locking per Peter Chubb's findings
   *
   *  25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>
   *   move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_unparse()
   *
   *  12 Feb 2002 - Matt Domsch <Matt_Domsch@dell.com>
   *   use list_for_each_safe when deleting vars.
   *   remove ifdef CONFIG_SMP around include <linux/smp.h>
   *   v0.04 release to linux-ia64@linuxia64.org
   *
   *  20 April 2001 - Matt Domsch <Matt_Domsch@dell.com>
   *   Moved vars from /proc/efi to /proc/efi/vars, and made
   *   efi.c own the /proc/efi directory.
   *   v0.03 release to linux-ia64@linuxia64.org
   *
   *  26 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
   *   At the request of Stephane, moved ownership of /proc/efi
   *   to efi.c, and now efivars lives under /proc/efi/vars.
   *
   *  12 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
   *   Feedback received from Stephane Eranian incorporated.
   *   efivar_write() checks copy_from_user() return value.
   *   efivar_read/write() returns proper errno.
   *   v0.02 release to linux-ia64@linuxia64.org
   *
   *  26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>
   *   v0.01 release to linux-ia64@linuxia64.org
   */

  #include <linux/capability.h>

  #include <linux/types.h>
  #include <linux/errno.h>
  #include <linux/init.h>

  #include <linux/mm.h>
  #include <linux/module.h>
  #include <linux/string.h>
  #include <linux/smp.h>
  #include <linux/efi.h>
  #include <linux/sysfs.h>
  #include <linux/kobject.h>
  #include <linux/device.h>

  #include <linux/slab.h>

  #include <linux/pstore.h>

  
  #include <asm/uaccess.h>
  
  #define EFIVARS_VERSION "0.08"
  #define EFIVARS_DATE "2004-May-17"
  
  MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
  MODULE_DESCRIPTION("sysfs interface to EFI Variables");
  MODULE_LICENSE("GPL");
  MODULE_VERSION(EFIVARS_VERSION);

  #define DUMP_NAME_LEN 52

  /*
   * The maximum size of VariableName + Data = 1024
   * Therefore, it's reasonable to save that much
   * space in each part of the structure,
   * and we use a page for reading/writing.
   */
  
  struct efi_variable {
  	efi_char16_t  VariableName[1024/sizeof(efi_char16_t)];
  	efi_guid_t    VendorGuid;
  	unsigned long DataSize;
  	__u8          Data[1024];
  	efi_status_t  Status;
  	__u32         Attributes;
  } __attribute__((packed));
  
  
  struct efivar_entry {

  	struct efivars *efivars;

  	struct efi_variable var;
  	struct list_head list;
  	struct kobject kobj;
  };

  struct efivar_attribute {
  	struct attribute attr;
  	ssize_t (*show) (struct efivar_entry *entry, char *buf);
  	ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
  };

  #define PSTORE_EFI_ATTRIBUTES \
  	(EFI_VARIABLE_NON_VOLATILE | \
  	 EFI_VARIABLE_BOOTSERVICE_ACCESS | \
  	 EFI_VARIABLE_RUNTIME_ACCESS)

  #define EFIVAR_ATTR(_name, _mode, _show, _store) \
  struct efivar_attribute efivar_attr_##_name = { \

  	.attr = {.name = __stringify(_name), .mode = _mode}, \

  	.show = _show, \
  	.store = _store, \
  };

  #define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
  #define to_efivar_entry(obj)  container_of(obj, struct efivar_entry, kobj)
  
  /*
   * Prototype for sysfs creation function
   */
  static int

  efivar_create_sysfs_entry(struct efivars *efivars,
  			  unsigned long variable_name_size,
  			  efi_char16_t *variable_name,
  			  efi_guid_t *vendor_guid);

  
  /* Return the number of unicode characters in data */
  static unsigned long

  utf16_strnlen(efi_char16_t *s, size_t maxlength)

  {
  	unsigned long length = 0;

  	while (*s++ != 0 && length < maxlength)

  		length++;
  	return length;
  }

  static inline unsigned long

  utf16_strlen(efi_char16_t *s)
  {
  	return utf16_strnlen(s, ~0UL);
  }

  /*
   * Return the number of bytes is the length of this string
   * Note: this is NOT the same as the number of unicode characters
   */
  static inline unsigned long

  utf16_strsize(efi_char16_t *data, unsigned long maxlength)

  {

  	return utf16_strnlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);

  }

  static inline int
  utf16_strncmp(const efi_char16_t *a, const efi_char16_t *b, size_t len)
  {
  	while (1) {
  		if (len == 0)
  			return 0;
  		if (*a < *b)
  			return -1;
  		if (*a > *b)
  			return 1;
  		if (*a == 0) /* implies *b == 0 */
  			return 0;
  		a++;
  		b++;
  		len--;
  	}
  }

  static efi_status_t

  get_var_data_locked(struct efivars *efivars, struct efi_variable *var)

  {
  	efi_status_t status;

  	var->DataSize = 1024;

  	status = efivars->ops->get_variable(var->VariableName,
  					    &var->VendorGuid,
  					    &var->Attributes,
  					    &var->DataSize,
  					    var->Data);

  	return status;
  }
  
  static efi_status_t
  get_var_data(struct efivars *efivars, struct efi_variable *var)
  {
  	efi_status_t status;
  
  	spin_lock(&efivars->lock);
  	status = get_var_data_locked(efivars, var);

  	spin_unlock(&efivars->lock);

  	if (status != EFI_SUCCESS) {
  		printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!
  ",
  			status);
  	}
  	return status;
  }
  
  static ssize_t
  efivar_guid_read(struct efivar_entry *entry, char *buf)
  {
  	struct efi_variable *var = &entry->var;
  	char *str = buf;
  
  	if (!entry || !buf)
  		return 0;
  
  	efi_guid_unparse(&var->VendorGuid, str);
  	str += strlen(str);
  	str += sprintf(str, "
  ");
  
  	return str - buf;
  }
  
  static ssize_t
  efivar_attr_read(struct efivar_entry *entry, char *buf)
  {
  	struct efi_variable *var = &entry->var;
  	char *str = buf;
  	efi_status_t status;
  
  	if (!entry || !buf)
  		return -EINVAL;

  	status = get_var_data(entry->efivars, var);

  	if (status != EFI_SUCCESS)
  		return -EIO;
  
  	if (var->Attributes & 0x1)
  		str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE
  ");
  	if (var->Attributes & 0x2)
  		str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS
  ");
  	if (var->Attributes & 0x4)
  		str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS
  ");
  	return str - buf;
  }
  
  static ssize_t
  efivar_size_read(struct efivar_entry *entry, char *buf)
  {
  	struct efi_variable *var = &entry->var;
  	char *str = buf;
  	efi_status_t status;
  
  	if (!entry || !buf)
  		return -EINVAL;

  	status = get_var_data(entry->efivars, var);

  	if (status != EFI_SUCCESS)
  		return -EIO;
  
  	str += sprintf(str, "0x%lx
  ", var->DataSize);
  	return str - buf;
  }
  
  static ssize_t
  efivar_data_read(struct efivar_entry *entry, char *buf)
  {
  	struct efi_variable *var = &entry->var;
  	efi_status_t status;
  
  	if (!entry || !buf)
  		return -EINVAL;

  	status = get_var_data(entry->efivars, var);

  	if (status != EFI_SUCCESS)
  		return -EIO;
  
  	memcpy(buf, var->Data, var->DataSize);
  	return var->DataSize;
  }
  /*
   * We allow each variable to be edited via rewriting the
   * entire efi variable structure.
   */
  static ssize_t
  efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
  {
  	struct efi_variable *new_var, *var = &entry->var;

  	struct efivars *efivars = entry->efivars;

  	efi_status_t status = EFI_NOT_FOUND;
  
  	if (count != sizeof(struct efi_variable))
  		return -EINVAL;
  
  	new_var = (struct efi_variable *)buf;
  	/*
  	 * If only updating the variable data, then the name
  	 * and guid should remain the same
  	 */
  	if (memcmp(new_var->VariableName, var->VariableName, sizeof(var->VariableName)) ||
  		efi_guidcmp(new_var->VendorGuid, var->VendorGuid)) {
  		printk(KERN_ERR "efivars: Cannot edit the wrong variable!
  ");
  		return -EINVAL;
  	}
  
  	if ((new_var->DataSize <= 0) || (new_var->Attributes == 0)){
  		printk(KERN_ERR "efivars: DataSize & Attributes must be valid!
  ");
  		return -EINVAL;
  	}

  	spin_lock(&efivars->lock);

  	status = efivars->ops->set_variable(new_var->VariableName,
  					    &new_var->VendorGuid,
  					    new_var->Attributes,
  					    new_var->DataSize,
  					    new_var->Data);

  	spin_unlock(&efivars->lock);

  
  	if (status != EFI_SUCCESS) {
  		printk(KERN_WARNING "efivars: set_variable() failed: status=%lx
  ",
  			status);
  		return -EIO;
  	}
  
  	memcpy(&entry->var, new_var, count);
  	return count;
  }
  
  static ssize_t
  efivar_show_raw(struct efivar_entry *entry, char *buf)
  {
  	struct efi_variable *var = &entry->var;
  	efi_status_t status;
  
  	if (!entry || !buf)
  		return 0;

  	status = get_var_data(entry->efivars, var);

  	if (status != EFI_SUCCESS)
  		return -EIO;
  
  	memcpy(buf, var, sizeof(*var));
  	return sizeof(*var);
  }
  
  /*
   * Generic read/write functions that call the specific functions of

   * the attributes...

   */
  static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
  				char *buf)
  {
  	struct efivar_entry *var = to_efivar_entry(kobj);
  	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);

  	ssize_t ret = -EIO;

  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EACCES;
  
  	if (efivar_attr->show) {
  		ret = efivar_attr->show(var, buf);
  	}
  	return ret;
  }
  
  static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
  				const char *buf, size_t count)
  {
  	struct efivar_entry *var = to_efivar_entry(kobj);
  	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);

  	ssize_t ret = -EIO;

  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EACCES;
  
  	if (efivar_attr->store)
  		ret = efivar_attr->store(var, buf, count);
  
  	return ret;
  }

  static const struct sysfs_ops efivar_attr_ops = {

  	.show = efivar_attr_show,
  	.store = efivar_attr_store,
  };
  
  static void efivar_release(struct kobject *kobj)
  {
  	struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);

  	kfree(var);
  }
  
  static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
  static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
  static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
  static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
  static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);
  
  static struct attribute *def_attrs[] = {
  	&efivar_attr_guid.attr,
  	&efivar_attr_size.attr,
  	&efivar_attr_attributes.attr,
  	&efivar_attr_data.attr,
  	&efivar_attr_raw_var.attr,
  	NULL,
  };

  static struct kobj_type efivar_ktype = {

  	.release = efivar_release,
  	.sysfs_ops = &efivar_attr_ops,
  	.default_attrs = def_attrs,
  };

  static struct pstore_info efi_pstore_info;

  static inline void
  efivar_unregister(struct efivar_entry *var)
  {

  	kobject_put(&var->kobj);

  }

  #ifdef CONFIG_PSTORE
  
  static int efi_pstore_open(struct pstore_info *psi)
  {
  	struct efivars *efivars = psi->data;
  
  	spin_lock(&efivars->lock);
  	efivars->walk_entry = list_first_entry(&efivars->list,
  					       struct efivar_entry, list);
  	return 0;
  }
  
  static int efi_pstore_close(struct pstore_info *psi)
  {
  	struct efivars *efivars = psi->data;
  
  	spin_unlock(&efivars->lock);
  	return 0;
  }
  
  static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,

  			       struct timespec *timespec,
  			       char **buf, struct pstore_info *psi)

  {
  	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
  	struct efivars *efivars = psi->data;
  	char name[DUMP_NAME_LEN];
  	int i;
  	unsigned int part, size;
  	unsigned long time;
  
  	while (&efivars->walk_entry->list != &efivars->list) {
  		if (!efi_guidcmp(efivars->walk_entry->var.VendorGuid,
  				 vendor)) {
  			for (i = 0; i < DUMP_NAME_LEN; i++) {
  				name[i] = efivars->walk_entry->var.VariableName[i];
  			}
  			if (sscanf(name, "dump-type%u-%u-%lu", type, &part, &time) == 3) {
  				*id = part;
  				timespec->tv_sec = time;
  				timespec->tv_nsec = 0;
  				get_var_data_locked(efivars, &efivars->walk_entry->var);
  				size = efivars->walk_entry->var.DataSize;

  				*buf = kmalloc(size, GFP_KERNEL);
  				if (*buf == NULL)
  					return -ENOMEM;
  				memcpy(*buf, efivars->walk_entry->var.Data,
  				       size);

  				efivars->walk_entry = list_entry(efivars->walk_entry->list.next,
  					           struct efivar_entry, list);
  				return size;
  			}
  		}
  		efivars->walk_entry = list_entry(efivars->walk_entry->list.next,
  						 struct efivar_entry, list);
  	}
  	return 0;
  }

  static int efi_pstore_write(enum pstore_type_id type,
  		enum kmsg_dump_reason reason, u64 *id,

  		unsigned int part, size_t size, struct pstore_info *psi)

  {
  	char name[DUMP_NAME_LEN];
  	char stub_name[DUMP_NAME_LEN];
  	efi_char16_t efi_name[DUMP_NAME_LEN];
  	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
  	struct efivars *efivars = psi->data;
  	struct efivar_entry *entry, *found = NULL;

  	int i, ret = 0;

  
  	sprintf(stub_name, "dump-type%u-%u-", type, part);
  	sprintf(name, "%s%lu", stub_name, get_seconds());
  
  	spin_lock(&efivars->lock);
  
  	for (i = 0; i < DUMP_NAME_LEN; i++)
  		efi_name[i] = stub_name[i];
  
  	/*
  	 * Clean up any entries with the same name
  	 */
  
  	list_for_each_entry(entry, &efivars->list, list) {
  		get_var_data_locked(efivars, &entry->var);

  		if (efi_guidcmp(entry->var.VendorGuid, vendor))
  			continue;
  		if (utf16_strncmp(entry->var.VariableName, efi_name,
  				  utf16_strlen(efi_name)))
  			continue;
  		/* Needs to be a prefix */
  		if (entry->var.VariableName[utf16_strlen(efi_name)] == 0)
  			continue;
  
  		/* found */
  		found = entry;

  		efivars->ops->set_variable(entry->var.VariableName,
  					   &entry->var.VendorGuid,
  					   PSTORE_EFI_ATTRIBUTES,

  					   0, NULL);

  	}
  
  	if (found)
  		list_del(&found->list);
  
  	for (i = 0; i < DUMP_NAME_LEN; i++)
  		efi_name[i] = name[i];

  	efivars->ops->set_variable(efi_name, &vendor, PSTORE_EFI_ATTRIBUTES,

  				   size, psi->buf);
  
  	spin_unlock(&efivars->lock);
  
  	if (found)
  		efivar_unregister(found);
  
  	if (size)

  		ret = efivar_create_sysfs_entry(efivars,

  					  utf16_strsize(efi_name,
  							DUMP_NAME_LEN * 2),

  					  efi_name, &vendor);

  	*id = part;
  	return ret;

  };
  
  static int efi_pstore_erase(enum pstore_type_id type, u64 id,
  			    struct pstore_info *psi)
  {

  	efi_pstore_write(type, 0, &id, (unsigned int)id, 0, psi);

  
  	return 0;
  }
  #else
  static int efi_pstore_open(struct pstore_info *psi)
  {
  	return 0;
  }
  
  static int efi_pstore_close(struct pstore_info *psi)
  {
  	return 0;
  }
  
  static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,

  			       struct timespec *timespec,
  			       char **buf, struct pstore_info *psi)

  {
  	return -1;
  }

  static int efi_pstore_write(enum pstore_type_id type,
  		enum kmsg_dump_reason reason, u64 *id,

  		unsigned int part, size_t size, struct pstore_info *psi)

  {
  	return 0;
  }
  
  static int efi_pstore_erase(enum pstore_type_id type, u64 id,
  			    struct pstore_info *psi)
  {
  	return 0;
  }
  #endif
  
  static struct pstore_info efi_pstore_info = {
  	.owner		= THIS_MODULE,
  	.name		= "efi",
  	.open		= efi_pstore_open,
  	.close		= efi_pstore_close,
  	.read		= efi_pstore_read,
  	.write		= efi_pstore_write,
  	.erase		= efi_pstore_erase,
  };

  static ssize_t efivar_create(struct file *filp, struct kobject *kobj,

  			     struct bin_attribute *bin_attr,
  			     char *buf, loff_t pos, size_t count)

  {
  	struct efi_variable *new_var = (struct efi_variable *)buf;

  	struct efivars *efivars = bin_attr->private;

  	struct efivar_entry *search_efivar, *n;

  	unsigned long strsize1, strsize2;

  	efi_status_t status = EFI_NOT_FOUND;
  	int found = 0;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EACCES;

  	spin_lock(&efivars->lock);

  
  	/*
  	 * Does this variable already exist?
  	 */

  	list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {

  		strsize1 = utf16_strsize(search_efivar->var.VariableName, 1024);
  		strsize2 = utf16_strsize(new_var->VariableName, 1024);

  		if (strsize1 == strsize2 &&
  			!memcmp(&(search_efivar->var.VariableName),
  				new_var->VariableName, strsize1) &&
  			!efi_guidcmp(search_efivar->var.VendorGuid,
  				new_var->VendorGuid)) {
  			found = 1;
  			break;
  		}
  	}
  	if (found) {

  		spin_unlock(&efivars->lock);

  		return -EINVAL;
  	}
  
  	/* now *really* create the variable via EFI */

  	status = efivars->ops->set_variable(new_var->VariableName,
  					    &new_var->VendorGuid,
  					    new_var->Attributes,
  					    new_var->DataSize,
  					    new_var->Data);

  
  	if (status != EFI_SUCCESS) {
  		printk(KERN_WARNING "efivars: set_variable() failed: status=%lx
  ",
  			status);

  		spin_unlock(&efivars->lock);

  		return -EIO;
  	}

  	spin_unlock(&efivars->lock);

  
  	/* Create the entry in sysfs.  Locking is not required here */

  	status = efivar_create_sysfs_entry(efivars,

  					   utf16_strsize(new_var->VariableName,
  							 1024),

  					   new_var->VariableName,
  					   &new_var->VendorGuid);

  	if (status) {
  		printk(KERN_WARNING "efivars: variable created, but sysfs entry wasn't.
  ");
  	}
  	return count;
  }

  static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,

  			     struct bin_attribute *bin_attr,
  			     char *buf, loff_t pos, size_t count)

  {
  	struct efi_variable *del_var = (struct efi_variable *)buf;

  	struct efivars *efivars = bin_attr->private;

  	struct efivar_entry *search_efivar, *n;

  	unsigned long strsize1, strsize2;

  	efi_status_t status = EFI_NOT_FOUND;
  	int found = 0;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return -EACCES;

  	spin_lock(&efivars->lock);

  
  	/*
  	 * Does this variable already exist?
  	 */

  	list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {

  		strsize1 = utf16_strsize(search_efivar->var.VariableName, 1024);
  		strsize2 = utf16_strsize(del_var->VariableName, 1024);

  		if (strsize1 == strsize2 &&
  			!memcmp(&(search_efivar->var.VariableName),
  				del_var->VariableName, strsize1) &&
  			!efi_guidcmp(search_efivar->var.VendorGuid,
  				del_var->VendorGuid)) {
  			found = 1;
  			break;
  		}
  	}
  	if (!found) {

  		spin_unlock(&efivars->lock);

  		return -EINVAL;
  	}
  	/* force the Attributes/DataSize to 0 to ensure deletion */
  	del_var->Attributes = 0;
  	del_var->DataSize = 0;

  	status = efivars->ops->set_variable(del_var->VariableName,
  					    &del_var->VendorGuid,
  					    del_var->Attributes,
  					    del_var->DataSize,
  					    del_var->Data);

  
  	if (status != EFI_SUCCESS) {
  		printk(KERN_WARNING "efivars: set_variable() failed: status=%lx
  ",
  			status);

  		spin_unlock(&efivars->lock);

  		return -EIO;
  	}

  	list_del(&search_efivar->list);

  	/* We need to release this lock before unregistering. */

  	spin_unlock(&efivars->lock);

  	efivar_unregister(search_efivar);
  
  	/* It's dead Jim.... */
  	return count;
  }

  /*
   * Let's not leave out systab information that snuck into
   * the efivars driver
   */

  static ssize_t systab_show(struct kobject *kobj,
  			   struct kobj_attribute *attr, char *buf)

  {
  	char *str = buf;

  	if (!kobj || !buf)

  		return -EINVAL;

  	if (efi.mps != EFI_INVALID_TABLE_ADDR)
  		str += sprintf(str, "MPS=0x%lx
  ", efi.mps);
  	if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
  		str += sprintf(str, "ACPI20=0x%lx
  ", efi.acpi20);
  	if (efi.acpi != EFI_INVALID_TABLE_ADDR)
  		str += sprintf(str, "ACPI=0x%lx
  ", efi.acpi);
  	if (efi.smbios != EFI_INVALID_TABLE_ADDR)
  		str += sprintf(str, "SMBIOS=0x%lx
  ", efi.smbios);
  	if (efi.hcdp != EFI_INVALID_TABLE_ADDR)
  		str += sprintf(str, "HCDP=0x%lx
  ", efi.hcdp);
  	if (efi.boot_info != EFI_INVALID_TABLE_ADDR)
  		str += sprintf(str, "BOOTINFO=0x%lx
  ", efi.boot_info);
  	if (efi.uga != EFI_INVALID_TABLE_ADDR)
  		str += sprintf(str, "UGA=0x%lx
  ", efi.uga);

  
  	return str - buf;
  }

  static struct kobj_attribute efi_attr_systab =
  			__ATTR(systab, 0400, systab_show, NULL);

  static struct attribute *efi_subsys_attrs[] = {
  	&efi_attr_systab.attr,

  	NULL,	/* maybe more in the future? */
  };

  static struct attribute_group efi_subsys_attr_group = {
  	.attrs = efi_subsys_attrs,
  };

  static struct kobject *efi_kobj;

  
  /*
   * efivar_create_sysfs_entry()
   * Requires:
   *    variable_name_size = number of bytes required to hold
   *                         variable_name (not counting the NULL
   *                         character at the end.

   *    efivars->lock is not held on entry or exit.

   * Returns 1 on failure, 0 on success
   */
  static int

  efivar_create_sysfs_entry(struct efivars *efivars,
  			  unsigned long variable_name_size,
  			  efi_char16_t *variable_name,
  			  efi_guid_t *vendor_guid)

  {
  	int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;
  	char *short_name;
  	struct efivar_entry *new_efivar;

  	short_name = kzalloc(short_name_size + 1, GFP_KERNEL);
  	new_efivar = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);

  
  	if (!short_name || !new_efivar)  {

  		kfree(short_name);
  		kfree(new_efivar);

  		return 1;
  	}

  	new_efivar->efivars = efivars;

  	memcpy(new_efivar->var.VariableName, variable_name,
  		variable_name_size);
  	memcpy(&(new_efivar->var.VendorGuid), vendor_guid, sizeof(efi_guid_t));
  
  	/* Convert Unicode to normal chars (assume top bits are 0),
  	   ala UTF-8 */
  	for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
  		short_name[i] = variable_name[i] & 0xFF;
  	}
  	/* This is ugly, but necessary to separate one vendor's
  	   private variables from another's.         */
  
  	*(short_name + strlen(short_name)) = '-';
  	efi_guid_unparse(vendor_guid, short_name + strlen(short_name));

  	new_efivar->kobj.kset = efivars->kset;

  	i = kobject_init_and_add(&new_efivar->kobj, &efivar_ktype, NULL,
  				 "%s", short_name);

  	if (i) {
  		kfree(short_name);
  		kfree(new_efivar);
  		return 1;
  	}

  	kobject_uevent(&new_efivar->kobj, KOBJ_ADD);

  	kfree(short_name);
  	short_name = NULL;

  	spin_lock(&efivars->lock);
  	list_add(&new_efivar->list, &efivars->list);
  	spin_unlock(&efivars->lock);

  
  	return 0;
  }

  
  static int
  create_efivars_bin_attributes(struct efivars *efivars)
  {
  	struct bin_attribute *attr;
  	int error;
  
  	/* new_var */
  	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
  	if (!attr)
  		return -ENOMEM;
  
  	attr->attr.name = "new_var";
  	attr->attr.mode = 0200;
  	attr->write = efivar_create;
  	attr->private = efivars;
  	efivars->new_var = attr;
  
  	/* del_var */
  	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
  	if (!attr) {
  		error = -ENOMEM;
  		goto out_free;
  	}
  	attr->attr.name = "del_var";
  	attr->attr.mode = 0200;
  	attr->write = efivar_delete;
  	attr->private = efivars;
  	efivars->del_var = attr;
  
  	sysfs_bin_attr_init(efivars->new_var);
  	sysfs_bin_attr_init(efivars->del_var);
  
  	/* Register */
  	error = sysfs_create_bin_file(&efivars->kset->kobj,
  				      efivars->new_var);
  	if (error) {
  		printk(KERN_ERR "efivars: unable to create new_var sysfs file"
  			" due to error %d
  ", error);
  		goto out_free;
  	}
  	error = sysfs_create_bin_file(&efivars->kset->kobj,
  				      efivars->del_var);
  	if (error) {
  		printk(KERN_ERR "efivars: unable to create del_var sysfs file"
  			" due to error %d
  ", error);
  		sysfs_remove_bin_file(&efivars->kset->kobj,
  				      efivars->new_var);
  		goto out_free;
  	}
  
  	return 0;
  out_free:

  	kfree(efivars->del_var);
  	efivars->del_var = NULL;

  	kfree(efivars->new_var);
  	efivars->new_var = NULL;
  	return error;
  }

  void unregister_efivars(struct efivars *efivars)

  {
  	struct efivar_entry *entry, *n;

  	list_for_each_entry_safe(entry, n, &efivars->list, list) {
  		spin_lock(&efivars->lock);
  		list_del(&entry->list);
  		spin_unlock(&efivars->lock);
  		efivar_unregister(entry);
  	}
  	if (efivars->new_var)
  		sysfs_remove_bin_file(&efivars->kset->kobj, efivars->new_var);
  	if (efivars->del_var)
  		sysfs_remove_bin_file(&efivars->kset->kobj, efivars->del_var);
  	kfree(efivars->new_var);
  	kfree(efivars->del_var);
  	kset_unregister(efivars->kset);
  }

  EXPORT_SYMBOL_GPL(unregister_efivars);

  int register_efivars(struct efivars *efivars,
  		     const struct efivar_operations *ops,
  		     struct kobject *parent_kobj)

  {
  	efi_status_t status = EFI_NOT_FOUND;
  	efi_guid_t vendor_guid;
  	efi_char16_t *variable_name;

  	unsigned long variable_name_size = 1024;

  	int error = 0;

  	variable_name = kzalloc(variable_name_size, GFP_KERNEL);

  	if (!variable_name) {
  		printk(KERN_ERR "efivars: Memory allocation failed.
  ");
  		return -ENOMEM;
  	}

  	spin_lock_init(&efivars->lock);
  	INIT_LIST_HEAD(&efivars->list);

  	efivars->ops = ops;

  	efivars->kset = kset_create_and_add("vars", NULL, parent_kobj);

  	if (!efivars->kset) {

  		printk(KERN_ERR "efivars: Subsystem registration failed.
  ");
  		error = -ENOMEM;

  		goto out;

  	}
  
  	/*
  	 * Per EFI spec, the maximum storage allocated for both
  	 * the variable name and variable data is 1024 bytes.
  	 */
  
  	do {
  		variable_name_size = 1024;

  		status = ops->get_next_variable(&variable_name_size,

  						variable_name,
  						&vendor_guid);
  		switch (status) {
  		case EFI_SUCCESS:

  			efivar_create_sysfs_entry(efivars,
  						  variable_name_size,
  						  variable_name,
  						  &vendor_guid);

  			break;
  		case EFI_NOT_FOUND:
  			break;
  		default:
  			printk(KERN_WARNING "efivars: get_next_variable: status=%lx
  ",
  				status);
  			status = EFI_NOT_FOUND;
  			break;
  		}
  	} while (status != EFI_NOT_FOUND);

  	error = create_efivars_bin_attributes(efivars);

  	if (error)

  		unregister_efivars(efivars);

  	efivars->efi_pstore_info = efi_pstore_info;
  
  	efivars->efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
  	if (efivars->efi_pstore_info.buf) {
  		efivars->efi_pstore_info.bufsize = 1024;
  		efivars->efi_pstore_info.data = efivars;

  		spin_lock_init(&efivars->efi_pstore_info.buf_lock);

  		pstore_register(&efivars->efi_pstore_info);
  	}

  out:
  	kfree(variable_name);

  	return error;
  }

  EXPORT_SYMBOL_GPL(register_efivars);

  static struct efivars __efivars;

  static struct efivar_operations ops;

  
  /*
   * For now we register the efi subsystem with the firmware subsystem
   * and the vars subsystem with the efi subsystem.  In the future, it
   * might make sense to split off the efi subsystem into its own
   * driver, but for now only efivars will register with it, so just
   * include it here.
   */
  
  static int __init
  efivars_init(void)
  {
  	int error = 0;
  
  	printk(KERN_INFO "EFI Variables Facility v%s %s
  ", EFIVARS_VERSION,
  	       EFIVARS_DATE);
  
  	if (!efi_enabled)

  		return 0;

  
  	/* For now we'll register the efi directory at /sys/firmware/efi */
  	efi_kobj = kobject_create_and_add("efi", firmware_kobj);
  	if (!efi_kobj) {
  		printk(KERN_ERR "efivars: Firmware registration failed.
  ");
  		return -ENOMEM;
  	}

  	ops.get_variable = efi.get_variable;
  	ops.set_variable = efi.set_variable;
  	ops.get_next_variable = efi.get_next_variable;
  	error = register_efivars(&__efivars, &ops, efi_kobj);

  	if (error)
  		goto err_put;

  
  	/* Don't forget the systab entry */
  	error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
  	if (error) {
  		printk(KERN_ERR
  		       "efivars: Sysfs attribute export failed with error %d.
  ",
  		       error);

  		goto err_unregister;

  	}

  	return 0;
  
  err_unregister:
  	unregister_efivars(&__efivars);
  err_put:
  	kobject_put(efi_kobj);

  	return error;
  }
  
  static void __exit
  efivars_exit(void)
  {

  	if (efi_enabled) {
  		unregister_efivars(&__efivars);
  		kobject_put(efi_kobj);
  	}

  }
  
  module_init(efivars_init);
  module_exit(efivars_exit);