[PATCH] efivars: add to drivers/firmware

From: Matt Tolentino <metolent@snoqualmie.dp.intel.com>

Second efivars driver update patch that adds efivars into the drivers/firmware
directory.

arch/ia64/Kconfig

@@ -294,6 +294,8 @@ config IA64_PALINFO
 	  To use this option, you have to ensure that the "/proc file system
 	  support" (CONFIG_PROC_FS) is enabled, too.
 
+source "drivers/firmware/Kconfig"
+
 source "fs/Kconfig.binfmt"
 
 endmenu

drivers/firmware/Kconfig

@@ -8,6 +8,7 @@ menu "Firmware Drivers"
 config EDD
 	tristate "BIOS Enhanced Disk Drive calls determine boot disk (EXPERIMENTAL)"
 	depends on EXPERIMENTAL
+	depends on !IA64
 	help
 	  Say Y or M here if you want to enable BIOS Enhanced Disk Drive
 	  Services real mode BIOS calls to determine which disk
@@ -16,4 +17,21 @@ config EDD
 	  This option is experimental, but believed to be safe,
 	  and most disk controller BIOS vendors do not yet implement this feature.
 
+config EFI_VARS
+	tristate "EFI Variable Support via sysfs"
+	depends on EFI
+	default n
+	help
+	  If you say Y here, you are able to get EFI (Extensible Firmware
+	  Interface) variable information via sysfs.  You may read,
+	  write, create, and destroy EFI variables through this interface.
+
+	  Note that using this driver in concert with efibootmgr requires
+	  at least test release version 0.5.0-test1 or later, which is
+	  available from Matt Domsch's website located at:
+	  http://domsch.com/linux/ia64/efibootmgr/testing/efibootmgr-0.5.0-test1.tar.gz
+
+	  Subsequent efibootmgr releases may be found at:
+	  http://domsch.com/linux/ia64/efibootmgr
+
 endmenu

drivers/firmware/Makefile

@@ -2,3 +2,4 @@
 # Makefile for the linux kernel.
 #
 obj-$(CONFIG_EDD)             	+= edd.o
+obj-$(CONFIG_EFI_VARS)		+= efivars.o

drivers/firmware/efivars.c

+/*
+ * EFI Variables - efivars.c
+ *
+ * Copyright (C) 2001,2003 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:
+ *
+ *  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/config.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/sched.h>		/* for capable() */
+#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 <asm/uaccess.h>
+
+MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
+MODULE_DESCRIPTION("sysfs interface to EFI Variables");
+MODULE_LICENSE("GPL");
+
+#define EFIVARS_VERSION "0.07 2003-Aug-29"
+
+/*
+ * efivars_lock protects two things:
+ * 1) efivar_list - adds, removals, reads, writes
+ * 2) efi.[gs]et_variable() calls.
+ * It must not be held when creating sysfs entries or calling kmalloc.
+ * efi.get_next_variable() is only called from efivars_init(),
+ * which is protected by the BKL, so that path is safe.
+ */
+static spinlock_t efivars_lock = SPIN_LOCK_UNLOCKED;
+static LIST_HEAD(efivar_list);
+
+/*
+ * 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 efi_variable var;
+	struct list_head list;
+	struct kobject kobj;
+};
+
+#define get_efivar_entry(n) list_entry(n, struct efivar_entry, list)
+
+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 EFI_ATTR(_name, _mode, _show, _store) \
+struct subsys_attribute efi_attr_##_name = { \
+	.attr {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
+	.show = _show, \
+	.store = _store, \
+};
+
+#define EFIVAR_ATTR(_name, _mode, _show, _store) \
+struct efivar_attribute efivar_attr_##_name = { \
+	.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
+	.show = _show, \
+	.store = _store, \
+};
+
+#define VAR_SUBSYS_ATTR(_name, _mode, _show, _store) \
+struct subsys_attribute var_subsys_attr_##_name = { \
+	.attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
+	.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(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
+utf8_strlen(efi_char16_t *data, unsigned long maxlength)
+{
+	unsigned long length = 0;
+
+	while (*data++ != 0 && length < maxlength)
+		length++;
+	return length;
+}
+
+/*
+ * 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
+utf8_strsize(efi_char16_t *data, unsigned long maxlength)
+{
+	return utf8_strlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);
+}
+
+static efi_status_t
+get_var_data(struct efi_variable *var)
+{
+	efi_status_t status;
+
+	spin_lock(&efivars_lock);
+	var->DataSize = 1024;
+	status = efi.get_variable(var->VariableName,
+				&var->VendorGuid,
+				&var->Attributes,
+				&var->DataSize,
+				var->Data);
+	spin_unlock(&efivars_lock);
+	if (status != EFI_SUCCESS) {
+		printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
+			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, "\n");
+
+	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(var);
+	if (status != EFI_SUCCESS)
+		return -EIO;
+
+	if (var->Attributes & 0x1)
+		str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
+	if (var->Attributes & 0x2)
+		str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
+	if (var->Attributes & 0x4)
+		str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
+	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(var);
+	if (status != EFI_SUCCESS)
+		return -EIO;
+
+	str += sprintf(str, "0x%lx\n", 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(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;
+	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!\n");
+		return -EINVAL;
+	}
+
+	if ((new_var->DataSize <= 0) || (new_var->Attributes == 0)){
+		printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
+		return -EINVAL;
+	}
+
+	spin_lock(&efivars_lock);
+	status = efi.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\n",
+			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(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 atttributes...
+ */
+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 = 0;
+
+	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 = 0;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	if (efivar_attr->store)
+		ret = efivar_attr->store(var, buf, count);
+
+	return ret;
+}
+
+static 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);
+	spin_lock(&efivars_lock);
+	list_del(&var->list);
+	spin_unlock(&efivars_lock);
+	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 ktype_efivar = {
+	.release = efivar_release,
+	.sysfs_ops = &efivar_attr_ops,
+	.default_attrs = def_attrs,
+};
+
+static ssize_t
+dummy(struct subsystem *sub, char *buf)
+{
+	return 0;
+}
+
+static inline void
+efivar_unregister(struct efivar_entry *var)
+{
+	kobject_unregister(&var->kobj);
+}
+
+
+static ssize_t
+efivar_create(struct subsystem *sub, const char *buf, size_t count)
+{
+	struct efi_variable *new_var = (struct efi_variable *)buf;
+	struct efivar_entry *search_efivar = NULL;
+	unsigned long strsize1, strsize2;
+	struct list_head *pos, *n;
+	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_safe(pos, n, &efivar_list) {
+		search_efivar = get_efivar_entry(pos);
+		strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
+		strsize2 = utf8_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 = efi.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\n",
+			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(utf8_strsize(new_var->VariableName,
+			1024), new_var->VariableName, &new_var->VendorGuid);
+	return status;
+}
+
+static ssize_t
+efivar_delete(struct subsystem *sub, const char *buf, size_t count)
+{
+	struct efi_variable *del_var = (struct efi_variable *)buf;
+	struct efivar_entry *search_efivar = NULL;
+	unsigned long strsize1, strsize2;
+	struct list_head *pos, *n;
+	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_safe(pos, n, &efivar_list) {
+		search_efivar = get_efivar_entry(pos);
+		strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
+		strsize2 = utf8_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 = efi.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\n",
+			status);
+		spin_unlock(&efivars_lock);
+		return -EIO;
+	}
+	/* We need to release this lock before unregistering. */
+	spin_unlock(&efivars_lock);
+
+	efivar_unregister(search_efivar);
+
+	/* It's dead Jim.... */
+	return status;
+}
+
+static VAR_SUBSYS_ATTR(new_var, 0200, dummy, efivar_create);
+static VAR_SUBSYS_ATTR(del_var, 0200, dummy, efivar_delete);
+
+static struct subsys_attribute *var_subsys_attrs[] = {
+	&var_subsys_attr_new_var,
+	&var_subsys_attr_del_var,
+	NULL,
+};
+
+/*
+ * Let's not leave out systab information that snuck into
+ * the efivars driver
+ */
+static ssize_t
+systab_read(struct subsystem *entry, char *buf)
+{
+	char *str = buf;
+
+	if (!entry || !buf)
+		return -EINVAL;
+
+	if (efi.mps)
+		str += sprintf(str, "MPS=0x%lx\n", __pa(efi.mps));
+	if (efi.acpi20)
+		str += sprintf(str, "ACPI20=0x%lx\n", __pa(efi.acpi20));
+	if (efi.acpi)
+		str += sprintf(str, "ACPI=0x%lx\n", __pa(efi.acpi));
+	if (efi.smbios)
+		str += sprintf(str, "SMBIOS=0x%lx\n", __pa(efi.smbios));
+	if (efi.hcdp)
+		str += sprintf(str, "HCDP=0x%lx\n", __pa(efi.hcdp));
+	if (efi.boot_info)
+		str += sprintf(str, "BOOTINFO=0x%lx\n", __pa(efi.boot_info));
+	if (efi.uga)
+		str += sprintf(str, "UGA=0x%lx\n", __pa(efi.uga));
+
+	return str - buf;
+}
+
+static EFI_ATTR(systab, 0400, systab_read, NULL);
+
+static struct subsys_attribute *efi_subsys_attrs[] = {
+	&efi_attr_systab,
+	NULL,	/* maybe more in the future? */
+};
+
+static decl_subsys(vars, &ktype_efivar, NULL);
+static decl_subsys(efi, NULL, NULL);
+
+/*
+ * 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(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 = kmalloc(short_name_size + 1, GFP_KERNEL);
+	new_efivar = kmalloc(sizeof(struct efivar_entry), GFP_KERNEL);
+
+	if (!short_name || !new_efivar)  {
+		if (short_name)        kfree(short_name);
+		if (new_efivar)        kfree(new_efivar);
+		return 1;
+	}
+	memset(short_name, 0, short_name_size+1);
+	memset(new_efivar, 0, sizeof(struct efivar_entry));
+
+	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));
+	*(short_name + strlen(short_name)) = ' ';
+
+	kobject_set_name(&new_efivar->kobj, short_name);
+	kobj_set_kset_s(new_efivar, vars_subsys);
+	kobject_register(&new_efivar->kobj);
+
+	kfree(short_name); short_name = NULL;
+
+	spin_lock(&efivars_lock);
+	list_add(&new_efivar->list, &efivar_list);
+	spin_unlock(&efivars_lock);
+
+	return 0;
+}
+/*
+ * 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)
+{
+	efi_status_t status = EFI_NOT_FOUND;
+	efi_guid_t vendor_guid;
+	efi_char16_t *variable_name = kmalloc(1024, GFP_KERNEL);
+	struct subsys_attribute *attr;
+	unsigned long variable_name_size = 1024;
+	int i, rc = 0, error = 0;
+
+	printk(KERN_INFO "EFI Variables Facility v%s\n", EFIVARS_VERSION);
+
+	/*
+	 * For now we'll register the efi subsys within this driver
+	 */
+
+	rc = firmware_register(&efi_subsys);
+
+	if (rc)
+		return rc;
+
+	kset_set_kset_s(&vars_subsys, efi_subsys);
+	subsystem_register(&vars_subsys);
+
+	/*
+	 * Per EFI spec, the maximum storage allocated for both
+	 * the variable name and variable data is 1024 bytes.
+	 */
+
+	memset(variable_name, 0, 1024);
+
+	do {
+		variable_name_size = 1024;
+
+		status = efi.get_next_variable(&variable_name_size,
+						variable_name,
+						&vendor_guid);
+		switch (status) {
+		case EFI_SUCCESS:
+			efivar_create_sysfs_entry(variable_name_size,
+							variable_name,
+							&vendor_guid);
+			break;
+		case EFI_NOT_FOUND:
+			break;
+		default:
+			printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
+				status);
+			status = EFI_NOT_FOUND;
+			break;
+		}
+	} while (status != EFI_NOT_FOUND);
+
+	/*
+	 * Now add attributes to allow creation of new vars
+	 * and deletion of existing ones...
+	 */
+
+	for (i = 0; (attr = var_subsys_attrs[i]) && !error; i++) {
+		if (attr->show && attr->store)
+			error = subsys_create_file(&vars_subsys, attr);
+	}
+
+	/* Don't forget the systab entry */
+
+	for (i = 0; (attr = efi_subsys_attrs[i]) && !error; i++) {
+		if (attr->show)
+			error = subsys_create_file(&efi_subsys, attr);
+	}
+
+	kfree(variable_name);
+	return 0;
+}
+
+static void __exit
+efivars_exit(void)
+{
+	struct list_head *pos, *n;
+
+	list_for_each_safe(pos, n, &efivar_list)
+		efivar_unregister(get_efivar_entry(pos));
+
+	subsystem_unregister(&vars_subsys);
+	firmware_unregister(&efi_subsys);
+}
+
+module_init(efivars_init);
+module_exit(efivars_exit);
+