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(EFI_BOOT))
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