linux/drivers/firmware/iscsi_ibft_find.c
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   1/*
   2 *  Copyright 2007-2010 Red Hat, Inc.
   3 *  by Peter Jones <pjones@redhat.com>
   4 *  Copyright 2007 IBM, Inc.
   5 *  by Konrad Rzeszutek <konradr@linux.vnet.ibm.com>
   6 *  Copyright 2008
   7 *  by Konrad Rzeszutek <ketuzsezr@darnok.org>
   8 *
   9 * This code finds the iSCSI Boot Format Table.
  10 *
  11 * This program is free software; you can redistribute it and/or modify
  12 * it under the terms of the GNU General Public License v2.0 as published by
  13 * the Free Software Foundation
  14 *
  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.
  19 */
  20
  21#include <linux/bootmem.h>
  22#include <linux/blkdev.h>
  23#include <linux/ctype.h>
  24#include <linux/device.h>
  25#include <linux/efi.h>
  26#include <linux/err.h>
  27#include <linux/init.h>
  28#include <linux/limits.h>
  29#include <linux/module.h>
  30#include <linux/pci.h>
  31#include <linux/stat.h>
  32#include <linux/string.h>
  33#include <linux/types.h>
  34#include <linux/acpi.h>
  35#include <linux/iscsi_ibft.h>
  36
  37#include <asm/mmzone.h>
  38
  39/*
  40 * Physical location of iSCSI Boot Format Table.
  41 */
  42struct acpi_table_ibft *ibft_addr;
  43EXPORT_SYMBOL_GPL(ibft_addr);
  44
  45static const struct {
  46        char *sign;
  47} ibft_signs[] = {
  48        { "iBFT" },
  49        { "BIFT" },     /* Broadcom iSCSI Offload */
  50};
  51
  52#define IBFT_SIGN_LEN 4
  53#define IBFT_START 0x80000 /* 512kB */
  54#define IBFT_END 0x100000 /* 1MB */
  55#define VGA_MEM 0xA0000 /* VGA buffer */
  56#define VGA_SIZE 0x20000 /* 128kB */
  57
  58static int __init find_ibft_in_mem(void)
  59{
  60        unsigned long pos;
  61        unsigned int len = 0;
  62        void *virt;
  63        int i;
  64
  65        for (pos = IBFT_START; pos < IBFT_END; pos += 16) {
  66                /* The table can't be inside the VGA BIOS reserved space,
  67                 * so skip that area */
  68                if (pos == VGA_MEM)
  69                        pos += VGA_SIZE;
  70                virt = isa_bus_to_virt(pos);
  71
  72                for (i = 0; i < ARRAY_SIZE(ibft_signs); i++) {
  73                        if (memcmp(virt, ibft_signs[i].sign, IBFT_SIGN_LEN) ==
  74                            0) {
  75                                unsigned long *addr =
  76                                    (unsigned long *)isa_bus_to_virt(pos + 4);
  77                                len = *addr;
  78                                /* if the length of the table extends past 1M,
  79                                 * the table cannot be valid. */
  80                                if (pos + len <= (IBFT_END-1)) {
  81                                        ibft_addr = (struct acpi_table_ibft *)virt;
  82                                        pr_info("iBFT found at 0x%lx.\n", pos);
  83                                        goto done;
  84                                }
  85                        }
  86                }
  87        }
  88done:
  89        return len;
  90}
  91/*
  92 * Routine used to find the iSCSI Boot Format Table. The logical
  93 * kernel address is set in the ibft_addr global variable.
  94 */
  95unsigned long __init find_ibft_region(unsigned long *sizep)
  96{
  97        ibft_addr = NULL;
  98
  99        /* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
 100         * only use ACPI for this */
 101
 102        if (!efi_enabled)
 103                find_ibft_in_mem();
 104
 105        if (ibft_addr) {
 106                *sizep = PAGE_ALIGN(ibft_addr->header.length);
 107                return (u64)isa_virt_to_bus(ibft_addr);
 108        }
 109
 110        *sizep = 0;
 111        return 0;
 112}
 113
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