2 * EFI Variables - efivars.c
4 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
5 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
7 * This code takes all variables accessible from EFI runtime and
8 * exports them via sysfs
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
26 * 26 Apr 2004 - Matt Domsch <Matt_Domsch@dell.com>
29 * 21 Apr 2004 - Matt Tolentino <matthew.e.tolentino@intel.com)
30 * converted driver to export variable information via sysfs
31 * and moved to drivers/firmware directory
32 * bumped revision number to v0.07 to reflect conversion & move
34 * 10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>
35 * fix locking per Peter Chubb's findings
37 * 25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>
38 * move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_unparse()
40 * 12 Feb 2002 - Matt Domsch <Matt_Domsch@dell.com>
41 * use list_for_each_safe when deleting vars.
42 * remove ifdef CONFIG_SMP around include <linux/smp.h>
43 * v0.04 release to linux-ia64@linuxia64.org
45 * 20 April 2001 - Matt Domsch <Matt_Domsch@dell.com>
46 * Moved vars from /proc/efi to /proc/efi/vars, and made
47 * efi.c own the /proc/efi directory.
48 * v0.03 release to linux-ia64@linuxia64.org
50 * 26 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
51 * At the request of Stephane, moved ownership of /proc/efi
52 * to efi.c, and now efivars lives under /proc/efi/vars.
54 * 12 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
55 * Feedback received from Stephane Eranian incorporated.
56 * efivar_write() checks copy_from_user() return value.
57 * efivar_read/write() returns proper errno.
58 * v0.02 release to linux-ia64@linuxia64.org
60 * 26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>
61 * v0.01 release to linux-ia64@linuxia64.org
64 #include <linux/config.h>
65 #include <linux/types.h>
66 #include <linux/errno.h>
67 #include <linux/init.h>
68 #include <linux/sched.h> /* for capable() */
70 #include <linux/module.h>
71 #include <linux/string.h>
72 #include <linux/smp.h>
73 #include <linux/efi.h>
74 #include <linux/sysfs.h>
75 #include <linux/kobject.h>
76 #include <linux/device.h>
78 #include <asm/uaccess.h>
80 MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
81 MODULE_DESCRIPTION("sysfs interface to EFI Variables");
82 MODULE_LICENSE("GPL");
84 #define EFIVARS_VERSION "0.07 2004-Apr-26"
87 * efivars_lock protects two things:
88 * 1) efivar_list - adds, removals, reads, writes
89 * 2) efi.[gs]et_variable() calls.
90 * It must not be held when creating sysfs entries or calling kmalloc.
91 * efi.get_next_variable() is only called from efivars_init(),
92 * which is protected by the BKL, so that path is safe.
94 static spinlock_t efivars_lock = SPIN_LOCK_UNLOCKED;
95 static LIST_HEAD(efivar_list);
98 * The maximum size of VariableName + Data = 1024
99 * Therefore, it's reasonable to save that much
100 * space in each part of the structure,
101 * and we use a page for reading/writing.
104 struct efi_variable {
105 efi_char16_t VariableName[1024/sizeof(efi_char16_t)];
106 efi_guid_t VendorGuid;
107 unsigned long DataSize;
111 } __attribute__((packed));
114 struct efivar_entry {
115 struct efi_variable var;
116 struct list_head list;
120 #define get_efivar_entry(n) list_entry(n, struct efivar_entry, list)
122 struct efivar_attribute {
123 struct attribute attr;
124 ssize_t (*show) (struct efivar_entry *entry, char *buf);
125 ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
129 #define EFI_ATTR(_name, _mode, _show, _store) \
130 struct subsys_attribute efi_attr_##_name = { \
131 .attr {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
136 #define EFIVAR_ATTR(_name, _mode, _show, _store) \
137 struct efivar_attribute efivar_attr_##_name = { \
138 .attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
143 #define VAR_SUBSYS_ATTR(_name, _mode, _show, _store) \
144 struct subsys_attribute var_subsys_attr_##_name = { \
145 .attr = {.name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE}, \
150 #define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
151 #define to_efivar_entry(obj) container_of(obj, struct efivar_entry, kobj)
154 * Prototype for sysfs creation function
157 efivar_create_sysfs_entry(unsigned long variable_name_size,
158 efi_char16_t *variable_name,
159 efi_guid_t *vendor_guid);
161 /* Return the number of unicode characters in data */
163 utf8_strlen(efi_char16_t *data, unsigned long maxlength)
165 unsigned long length = 0;
167 while (*data++ != 0 && length < maxlength)
173 * Return the number of bytes is the length of this string
174 * Note: this is NOT the same as the number of unicode characters
176 static inline unsigned long
177 utf8_strsize(efi_char16_t *data, unsigned long maxlength)
179 return utf8_strlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);
183 get_var_data(struct efi_variable *var)
187 spin_lock(&efivars_lock);
188 var->DataSize = 1024;
189 status = efi.get_variable(var->VariableName,
194 spin_unlock(&efivars_lock);
195 if (status != EFI_SUCCESS) {
196 printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
203 efivar_guid_read(struct efivar_entry *entry, char *buf)
205 struct efi_variable *var = &entry->var;
211 efi_guid_unparse(&var->VendorGuid, str);
213 str += sprintf(str, "\n");
219 efivar_attr_read(struct efivar_entry *entry, char *buf)
221 struct efi_variable *var = &entry->var;
228 status = get_var_data(var);
229 if (status != EFI_SUCCESS)
232 if (var->Attributes & 0x1)
233 str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
234 if (var->Attributes & 0x2)
235 str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
236 if (var->Attributes & 0x4)
237 str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
242 efivar_size_read(struct efivar_entry *entry, char *buf)
244 struct efi_variable *var = &entry->var;
251 status = get_var_data(var);
252 if (status != EFI_SUCCESS)
255 str += sprintf(str, "0x%lx\n", var->DataSize);
260 efivar_data_read(struct efivar_entry *entry, char *buf)
262 struct efi_variable *var = &entry->var;
268 status = get_var_data(var);
269 if (status != EFI_SUCCESS)
272 memcpy(buf, var->Data, var->DataSize);
273 return var->DataSize;
276 * We allow each variable to be edited via rewriting the
277 * entire efi variable structure.
280 efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
282 struct efi_variable *new_var, *var = &entry->var;
283 efi_status_t status = EFI_NOT_FOUND;
285 if (count != sizeof(struct efi_variable))
288 new_var = (struct efi_variable *)buf;
290 * If only updating the variable data, then the name
291 * and guid should remain the same
293 if (memcmp(new_var->VariableName, var->VariableName, sizeof(var->VariableName)) ||
294 efi_guidcmp(new_var->VendorGuid, var->VendorGuid)) {
295 printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
299 if ((new_var->DataSize <= 0) || (new_var->Attributes == 0)){
300 printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
304 spin_lock(&efivars_lock);
305 status = efi.set_variable(new_var->VariableName,
306 &new_var->VendorGuid,
311 spin_unlock(&efivars_lock);
313 if (status != EFI_SUCCESS) {
314 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
319 memcpy(&entry->var, new_var, count);
324 efivar_show_raw(struct efivar_entry *entry, char *buf)
326 struct efi_variable *var = &entry->var;
332 status = get_var_data(var);
333 if (status != EFI_SUCCESS)
336 memcpy(buf, var, sizeof(*var));
341 * Generic read/write functions that call the specific functions of
344 static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
347 struct efivar_entry *var = to_efivar_entry(kobj);
348 struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
351 if (!capable(CAP_SYS_ADMIN))
354 if (efivar_attr->show) {
355 ret = efivar_attr->show(var, buf);
360 static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
361 const char *buf, size_t count)
363 struct efivar_entry *var = to_efivar_entry(kobj);
364 struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
367 if (!capable(CAP_SYS_ADMIN))
370 if (efivar_attr->store)
371 ret = efivar_attr->store(var, buf, count);
376 static struct sysfs_ops efivar_attr_ops = {
377 .show = efivar_attr_show,
378 .store = efivar_attr_store,
381 static void efivar_release(struct kobject *kobj)
383 struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
384 spin_lock(&efivars_lock);
385 list_del(&var->list);
386 spin_unlock(&efivars_lock);
390 static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
391 static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
392 static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
393 static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
394 static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);
396 static struct attribute *def_attrs[] = {
397 &efivar_attr_guid.attr,
398 &efivar_attr_size.attr,
399 &efivar_attr_attributes.attr,
400 &efivar_attr_data.attr,
401 &efivar_attr_raw_var.attr,
405 static struct kobj_type ktype_efivar = {
406 .release = efivar_release,
407 .sysfs_ops = &efivar_attr_ops,
408 .default_attrs = def_attrs,
412 dummy(struct subsystem *sub, char *buf)
418 efivar_unregister(struct efivar_entry *var)
420 kobject_unregister(&var->kobj);
425 efivar_create(struct subsystem *sub, const char *buf, size_t count)
427 struct efi_variable *new_var = (struct efi_variable *)buf;
428 struct efivar_entry *search_efivar = NULL;
429 unsigned long strsize1, strsize2;
430 struct list_head *pos, *n;
431 efi_status_t status = EFI_NOT_FOUND;
434 if (!capable(CAP_SYS_ADMIN))
437 spin_lock(&efivars_lock);
440 * Does this variable already exist?
442 list_for_each_safe(pos, n, &efivar_list) {
443 search_efivar = get_efivar_entry(pos);
444 strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
445 strsize2 = utf8_strsize(new_var->VariableName, 1024);
446 if (strsize1 == strsize2 &&
447 !memcmp(&(search_efivar->var.VariableName),
448 new_var->VariableName, strsize1) &&
449 !efi_guidcmp(search_efivar->var.VendorGuid,
450 new_var->VendorGuid)) {
456 spin_unlock(&efivars_lock);
460 /* now *really* create the variable via EFI */
461 status = efi.set_variable(new_var->VariableName,
462 &new_var->VendorGuid,
467 if (status != EFI_SUCCESS) {
468 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
470 spin_unlock(&efivars_lock);
473 spin_unlock(&efivars_lock);
475 /* Create the entry in sysfs. Locking is not required here */
476 status = efivar_create_sysfs_entry(utf8_strsize(new_var->VariableName,
477 1024), new_var->VariableName, &new_var->VendorGuid);
479 printk(KERN_WARNING "efivars: variable created, but sysfs entry wasn't.\n");
485 efivar_delete(struct subsystem *sub, const char *buf, size_t count)
487 struct efi_variable *del_var = (struct efi_variable *)buf;
488 struct efivar_entry *search_efivar = NULL;
489 unsigned long strsize1, strsize2;
490 struct list_head *pos, *n;
491 efi_status_t status = EFI_NOT_FOUND;
494 if (!capable(CAP_SYS_ADMIN))
497 spin_lock(&efivars_lock);
500 * Does this variable already exist?
502 list_for_each_safe(pos, n, &efivar_list) {
503 search_efivar = get_efivar_entry(pos);
504 strsize1 = utf8_strsize(search_efivar->var.VariableName, 1024);
505 strsize2 = utf8_strsize(del_var->VariableName, 1024);
506 if (strsize1 == strsize2 &&
507 !memcmp(&(search_efivar->var.VariableName),
508 del_var->VariableName, strsize1) &&
509 !efi_guidcmp(search_efivar->var.VendorGuid,
510 del_var->VendorGuid)) {
516 spin_unlock(&efivars_lock);
519 /* force the Attributes/DataSize to 0 to ensure deletion */
520 del_var->Attributes = 0;
521 del_var->DataSize = 0;
523 status = efi.set_variable(del_var->VariableName,
524 &del_var->VendorGuid,
529 if (status != EFI_SUCCESS) {
530 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
532 spin_unlock(&efivars_lock);
535 /* We need to release this lock before unregistering. */
536 spin_unlock(&efivars_lock);
538 efivar_unregister(search_efivar);
540 /* It's dead Jim.... */
544 static VAR_SUBSYS_ATTR(new_var, 0200, dummy, efivar_create);
545 static VAR_SUBSYS_ATTR(del_var, 0200, dummy, efivar_delete);
547 static struct subsys_attribute *var_subsys_attrs[] = {
548 &var_subsys_attr_new_var,
549 &var_subsys_attr_del_var,
554 * Let's not leave out systab information that snuck into
558 systab_read(struct subsystem *entry, char *buf)
566 str += sprintf(str, "MPS=0x%lx\n", __pa(efi.mps));
568 str += sprintf(str, "ACPI20=0x%lx\n", __pa(efi.acpi20));
570 str += sprintf(str, "ACPI=0x%lx\n", __pa(efi.acpi));
572 str += sprintf(str, "SMBIOS=0x%lx\n", __pa(efi.smbios));
574 str += sprintf(str, "HCDP=0x%lx\n", __pa(efi.hcdp));
576 str += sprintf(str, "BOOTINFO=0x%lx\n", __pa(efi.boot_info));
578 str += sprintf(str, "UGA=0x%lx\n", __pa(efi.uga));
583 static EFI_ATTR(systab, 0400, systab_read, NULL);
585 static struct subsys_attribute *efi_subsys_attrs[] = {
587 NULL, /* maybe more in the future? */
590 static decl_subsys(vars, &ktype_efivar, NULL);
591 static decl_subsys(efi, NULL, NULL);
594 * efivar_create_sysfs_entry()
596 * variable_name_size = number of bytes required to hold
597 * variable_name (not counting the NULL
598 * character at the end.
599 * efivars_lock is not held on entry or exit.
600 * Returns 1 on failure, 0 on success
603 efivar_create_sysfs_entry(unsigned long variable_name_size,
604 efi_char16_t *variable_name,
605 efi_guid_t *vendor_guid)
607 int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;
609 struct efivar_entry *new_efivar;
611 short_name = kmalloc(short_name_size + 1, GFP_KERNEL);
612 new_efivar = kmalloc(sizeof(struct efivar_entry), GFP_KERNEL);
614 if (!short_name || !new_efivar) {
615 if (short_name) kfree(short_name);
616 if (new_efivar) kfree(new_efivar);
619 memset(short_name, 0, short_name_size+1);
620 memset(new_efivar, 0, sizeof(struct efivar_entry));
622 memcpy(new_efivar->var.VariableName, variable_name,
624 memcpy(&(new_efivar->var.VendorGuid), vendor_guid, sizeof(efi_guid_t));
626 /* Convert Unicode to normal chars (assume top bits are 0),
628 for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
629 short_name[i] = variable_name[i] & 0xFF;
631 /* This is ugly, but necessary to separate one vendor's
632 private variables from another's. */
634 *(short_name + strlen(short_name)) = '-';
635 efi_guid_unparse(vendor_guid, short_name + strlen(short_name));
637 kobject_set_name(&new_efivar->kobj, short_name);
638 kobj_set_kset_s(new_efivar, vars_subsys);
639 kobject_register(&new_efivar->kobj);
641 kfree(short_name); short_name = NULL;
643 spin_lock(&efivars_lock);
644 list_add(&new_efivar->list, &efivar_list);
645 spin_unlock(&efivars_lock);
650 * For now we register the efi subsystem with the firmware subsystem
651 * and the vars subsystem with the efi subsystem. In the future, it
652 * might make sense to split off the efi subsystem into its own
653 * driver, but for now only efivars will register with it, so just
660 efi_status_t status = EFI_NOT_FOUND;
661 efi_guid_t vendor_guid;
662 efi_char16_t *variable_name = kmalloc(1024, GFP_KERNEL);
663 struct subsys_attribute *attr;
664 unsigned long variable_name_size = 1024;
665 int i, rc = 0, error = 0;
667 printk(KERN_INFO "EFI Variables Facility v%s\n", EFIVARS_VERSION);
670 * For now we'll register the efi subsys within this driver
673 rc = firmware_register(&efi_subsys);
678 kset_set_kset_s(&vars_subsys, efi_subsys);
679 subsystem_register(&vars_subsys);
682 * Per EFI spec, the maximum storage allocated for both
683 * the variable name and variable data is 1024 bytes.
686 memset(variable_name, 0, 1024);
689 variable_name_size = 1024;
691 status = efi.get_next_variable(&variable_name_size,
696 efivar_create_sysfs_entry(variable_name_size,
703 printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
705 status = EFI_NOT_FOUND;
708 } while (status != EFI_NOT_FOUND);
711 * Now add attributes to allow creation of new vars
712 * and deletion of existing ones...
715 for (i = 0; (attr = var_subsys_attrs[i]) && !error; i++) {
716 if (attr->show && attr->store)
717 error = subsys_create_file(&vars_subsys, attr);
720 /* Don't forget the systab entry */
722 for (i = 0; (attr = efi_subsys_attrs[i]) && !error; i++) {
724 error = subsys_create_file(&efi_subsys, attr);
727 kfree(variable_name);
734 struct list_head *pos, *n;
736 list_for_each_safe(pos, n, &efivar_list)
737 efivar_unregister(get_efivar_entry(pos));
739 subsystem_unregister(&vars_subsys);
740 firmware_unregister(&efi_subsys);
743 module_init(efivars_init);
744 module_exit(efivars_exit);