LXR linux/drivers/firmware/efi/efi.c

   1/*
   2 * efi.c - EFI subsystem
   3 *
   4 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
   5 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
   6 * Copyright (C) 2013 Tom Gundersen <teg@jklm.no>
   7 *
   8 * This code registers /sys/firmware/efi{,/efivars} when EFI is supported,
   9 * allowing the efivarfs to be mounted or the efivars module to be loaded.
  10 * The existance of /sys/firmware/efi may also be used by userspace to
  11 * determine that the system supports EFI.
  12 *
  13 * This file is released under the GPLv2.
  14 */
  15
  16#include <linux/kobject.h>
  17#include <linux/module.h>
  18#include <linux/init.h>
  19#include <linux/device.h>
  20#include <linux/efi.h>
  21
  22static struct kobject *efi_kobj;
  23static struct kobject *efivars_kobj;
  24
  25/*
  26 * Let's not leave out systab information that snuck into
  27 * the efivars driver
  28 */
  29static ssize_t systab_show(struct kobject *kobj,
  30                           struct kobj_attribute *attr, char *buf)
  31{
  32        char *str = buf;
  33
  34        if (!kobj || !buf)
  35                return -EINVAL;
  36
  37        if (efi.mps != EFI_INVALID_TABLE_ADDR)
  38                str += sprintf(str, "MPS=0x%lx\n", efi.mps);
  39        if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
  40                str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20);
  41        if (efi.acpi != EFI_INVALID_TABLE_ADDR)
  42                str += sprintf(str, "ACPI=0x%lx\n", efi.acpi);
  43        if (efi.smbios != EFI_INVALID_TABLE_ADDR)
  44                str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);
  45        if (efi.hcdp != EFI_INVALID_TABLE_ADDR)
  46                str += sprintf(str, "HCDP=0x%lx\n", efi.hcdp);
  47        if (efi.boot_info != EFI_INVALID_TABLE_ADDR)
  48                str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info);
  49        if (efi.uga != EFI_INVALID_TABLE_ADDR)
  50                str += sprintf(str, "UGA=0x%lx\n", efi.uga);
  51
  52        return str - buf;
  53}
  54
  55static struct kobj_attribute efi_attr_systab =
  56                        __ATTR(systab, 0400, systab_show, NULL);
  57
  58static struct attribute *efi_subsys_attrs[] = {
  59        &efi_attr_systab.attr,
  60        NULL,   /* maybe more in the future? */
  61};
  62
  63static struct attribute_group efi_subsys_attr_group = {
  64        .attrs = efi_subsys_attrs,
  65};
  66
  67static struct efivars generic_efivars;
  68static struct efivar_operations generic_ops;
  69
  70static int generic_ops_register(void)
  71{
  72        generic_ops.get_variable = efi.get_variable;
  73        generic_ops.set_variable = efi.set_variable;
  74        generic_ops.get_next_variable = efi.get_next_variable;
  75        generic_ops.query_variable_store = efi_query_variable_store;
  76
  77        return efivars_register(&generic_efivars, &generic_ops, efi_kobj);
  78}
  79
  80static void generic_ops_unregister(void)
  81{
  82        efivars_unregister(&generic_efivars);
  83}
  84
  85/*
  86 * We register the efi subsystem with the firmware subsystem and the
  87 * efivars subsystem with the efi subsystem, if the system was booted with
  88 * EFI.
  89 */
  90static int __init efisubsys_init(void)
  91{
  92        int error;
  93
  94        if (!efi_enabled(EFI_BOOT))
  95                return 0;
  96
  97        /* We register the efi directory at /sys/firmware/efi */
  98        efi_kobj = kobject_create_and_add("efi", firmware_kobj);
  99        if (!efi_kobj) {
 100                pr_err("efi: Firmware registration failed.\n");
 101                return -ENOMEM;
 102        }
 103
 104        error = generic_ops_register();
 105        if (error)
 106                goto err_put;
 107
 108        error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
 109        if (error) {
 110                pr_err("efi: Sysfs attribute export failed with error %d.\n",
 111                       error);
 112                goto err_unregister;
 113        }
 114
 115        /* and the standard mountpoint for efivarfs */
 116        efivars_kobj = kobject_create_and_add("efivars", efi_kobj);
 117        if (!efivars_kobj) {
 118                pr_err("efivars: Subsystem registration failed.\n");
 119                error = -ENOMEM;
 120                goto err_remove_group;
 121        }
 122
 123        return 0;
 124
 125err_remove_group:
 126        sysfs_remove_group(efi_kobj, &efi_subsys_attr_group);
 127err_unregister:
 128        generic_ops_unregister();
 129err_put:
 130        kobject_put(efi_kobj);
 131        return error;
 132}
 133
 134subsys_initcall(efisubsys_init);
 135