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  */
42 struct acpi_table_ibft *ibft_addr;
43 EXPORT_SYMBOL_GPL(ibft_addr);
44 
45 static const struct {
46 	char *sign;
47 } ibft_signs[] = {
48 #ifdef CONFIG_ACPI
49 	/*
50 	 * One spec says "IBFT", the other says "iBFT". We have to check
51 	 * for both.
52 	 */
53 	{ ACPI_SIG_IBFT },
54 #endif
55 	{ "iBFT" },
56 	{ "BIFT" },	/* Broadcom iSCSI Offload */
57 };
58 
59 #define IBFT_SIGN_LEN 4
60 #define IBFT_START 0x80000 /* 512kB */
61 #define IBFT_END 0x100000 /* 1MB */
62 #define VGA_MEM 0xA0000 /* VGA buffer */
63 #define VGA_SIZE 0x20000 /* 128kB */
64 
65 #ifdef CONFIG_ACPI
66 static int __init acpi_find_ibft(struct acpi_table_header *header)
67 {
68 	ibft_addr = (struct acpi_table_ibft *)header;
69 	return 0;
70 }
71 #endif /* CONFIG_ACPI */
72 
73 static int __init find_ibft_in_mem(void)
74 {
75 	unsigned long pos;
76 	unsigned int len = 0;
77 	void *virt;
78 	int i;
79 
80 	for (pos = IBFT_START; pos < IBFT_END; pos += 16) {
81 		/* The table can't be inside the VGA BIOS reserved space,
82 		 * so skip that area */
83 		if (pos == VGA_MEM)
84 			pos += VGA_SIZE;
85 		virt = isa_bus_to_virt(pos);
86 
87 		for (i = 0; i < ARRAY_SIZE(ibft_signs); i++) {
88 			if (memcmp(virt, ibft_signs[i].sign, IBFT_SIGN_LEN) ==
89 			    0) {
90 				unsigned long *addr =
91 				    (unsigned long *)isa_bus_to_virt(pos + 4);
92 				len = *addr;
93 				/* if the length of the table extends past 1M,
94 				 * the table cannot be valid. */
95 				if (pos + len <= (IBFT_END-1)) {
96 					ibft_addr = (struct acpi_table_ibft *)virt;
97 					goto done;
98 				}
99 			}
100 		}
101 	}
102 done:
103 	return len;
104 }
105 /*
106  * Routine used to find the iSCSI Boot Format Table. The logical
107  * kernel address is set in the ibft_addr global variable.
108  */
109 unsigned long __init find_ibft_region(unsigned long *sizep)
110 {
111 	int i;
112 	ibft_addr = NULL;
113 
114 #ifdef CONFIG_ACPI
115 	for (i = 0; i < ARRAY_SIZE(ibft_signs) && !ibft_addr; i++)
116 		acpi_table_parse(ibft_signs[i].sign, acpi_find_ibft);
117 #endif /* CONFIG_ACPI */
118 
119 	/* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
120 	 * only use ACPI for this */
121 
122 	if (!ibft_addr && !efi_enabled)
123 		find_ibft_in_mem();
124 
125 	if (ibft_addr) {
126 		*sizep = PAGE_ALIGN(ibft_addr->header.length);
127 		return (u64)isa_virt_to_bus(ibft_addr);
128 	}
129 
130 	*sizep = 0;
131 	return 0;
132 }
133