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