135 lines
3.5 KiB
C
135 lines
3.5 KiB
C
/*
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* efi.c - EFI subsystem
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*
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* Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
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* Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
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* Copyright (C) 2013 Tom Gundersen <teg@jklm.no>
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*
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* This code registers /sys/firmware/efi{,/efivars} when EFI is supported,
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* allowing the efivarfs to be mounted or the efivars module to be loaded.
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* The existance of /sys/firmware/efi may also be used by userspace to
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* determine that the system supports EFI.
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*
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* This file is released under the GPLv2.
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*/
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#include <linux/kobject.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/device.h>
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#include <linux/efi.h>
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static struct kobject *efi_kobj;
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static struct kobject *efivars_kobj;
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/*
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* Let's not leave out systab information that snuck into
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* the efivars driver
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*/
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static ssize_t systab_show(struct kobject *kobj,
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struct kobj_attribute *attr, char *buf)
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{
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char *str = buf;
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if (!kobj || !buf)
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return -EINVAL;
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if (efi.mps != EFI_INVALID_TABLE_ADDR)
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str += sprintf(str, "MPS=0x%lx\n", efi.mps);
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if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
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str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20);
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if (efi.acpi != EFI_INVALID_TABLE_ADDR)
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str += sprintf(str, "ACPI=0x%lx\n", efi.acpi);
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if (efi.smbios != EFI_INVALID_TABLE_ADDR)
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str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);
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if (efi.hcdp != EFI_INVALID_TABLE_ADDR)
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str += sprintf(str, "HCDP=0x%lx\n", efi.hcdp);
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if (efi.boot_info != EFI_INVALID_TABLE_ADDR)
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str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info);
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if (efi.uga != EFI_INVALID_TABLE_ADDR)
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str += sprintf(str, "UGA=0x%lx\n", efi.uga);
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return str - buf;
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}
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static struct kobj_attribute efi_attr_systab =
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__ATTR(systab, 0400, systab_show, NULL);
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static struct attribute *efi_subsys_attrs[] = {
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&efi_attr_systab.attr,
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NULL, /* maybe more in the future? */
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};
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static struct attribute_group efi_subsys_attr_group = {
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.attrs = efi_subsys_attrs,
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};
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static struct efivars generic_efivars;
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static struct efivar_operations generic_ops;
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static int generic_ops_register(void)
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{
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generic_ops.get_variable = efi.get_variable;
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generic_ops.set_variable = efi.set_variable;
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generic_ops.get_next_variable = efi.get_next_variable;
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generic_ops.query_variable_store = efi_query_variable_store;
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return efivars_register(&generic_efivars, &generic_ops, efi_kobj);
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}
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static void generic_ops_unregister(void)
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{
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efivars_unregister(&generic_efivars);
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}
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/*
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* We register the efi subsystem with the firmware subsystem and the
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* efivars subsystem with the efi subsystem, if the system was booted with
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* EFI.
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*/
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static int __init efisubsys_init(void)
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{
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int error;
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if (!efi_enabled(EFI_BOOT))
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return 0;
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/* We register the efi directory at /sys/firmware/efi */
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efi_kobj = kobject_create_and_add("efi", firmware_kobj);
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if (!efi_kobj) {
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pr_err("efi: Firmware registration failed.\n");
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return -ENOMEM;
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}
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error = generic_ops_register();
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if (error)
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goto err_put;
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error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
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if (error) {
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pr_err("efi: Sysfs attribute export failed with error %d.\n",
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error);
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goto err_unregister;
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}
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/* and the standard mountpoint for efivarfs */
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efivars_kobj = kobject_create_and_add("efivars", efi_kobj);
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if (!efivars_kobj) {
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pr_err("efivars: Subsystem registration failed.\n");
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error = -ENOMEM;
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goto err_remove_group;
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}
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return 0;
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err_remove_group:
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sysfs_remove_group(efi_kobj, &efi_subsys_attr_group);
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err_unregister:
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generic_ops_unregister();
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err_put:
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kobject_put(efi_kobj);
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return error;
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}
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subsys_initcall(efisubsys_init);
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