1 /*
2  *  Copyright 2007 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/err.h>
26 #include <linux/init.h>
27 #include <linux/limits.h>
28 #include <linux/module.h>
29 #include <linux/pci.h>
30 #include <linux/slab.h>
31 #include <linux/stat.h>
32 #include <linux/string.h>
33 #include <linux/types.h>
34 
35 #include <asm/mmzone.h>
36 
37 /*
38  * Physical location of iSCSI Boot Format Table.
39  */
40 struct ibft_table_header *ibft_addr;
41 EXPORT_SYMBOL_GPL(ibft_addr);
42 
43 #define IBFT_SIGN "iBFT"
44 #define IBFT_SIGN_LEN 4
45 #define IBFT_START 0x80000 /* 512kB */
46 #define IBFT_END 0x100000 /* 1MB */
47 #define VGA_MEM 0xA0000 /* VGA buffer */
48 #define VGA_SIZE 0x20000 /* 128kB */
49 
50 
51 /*
52  * Routine used to find the iSCSI Boot Format Table. The logical
53  * kernel address is set in the ibft_addr global variable.
54  */
55 void __init reserve_ibft_region(void)
56 {
57 	unsigned long pos;
58 	unsigned int len = 0;
59 	void *virt;
60 
61 	ibft_addr = NULL;
62 
63 	for (pos = IBFT_START; pos < IBFT_END; pos += 16) {
64 		/* The table can't be inside the VGA BIOS reserved space,
65 		 * so skip that area */
66 		if (pos == VGA_MEM)
67 			pos += VGA_SIZE;
68 		virt = phys_to_virt(pos);
69 		if (memcmp(virt, IBFT_SIGN, IBFT_SIGN_LEN) == 0) {
70 			unsigned long *addr =
71 			    (unsigned long *)phys_to_virt(pos + 4);
72 			len = *addr;
73 			/* if the length of the table extends past 1M,
74 			 * the table cannot be valid. */
75 			if (pos + len <= (IBFT_END-1)) {
76 				ibft_addr = (struct ibft_table_header *)virt;
77 				break;
78 			}
79 		}
80 	}
81 	if (ibft_addr)
82 		reserve_bootmem(pos, PAGE_ALIGN(len), BOOTMEM_DEFAULT);
83 }
84 EXPORT_SYMBOL_GPL(reserve_ibft_region);
85