1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  Copyright 2007-2010 Red Hat, Inc.
4  *  by Peter Jones <pjones@redhat.com>
5  *  Copyright 2007 IBM, Inc.
6  *  by Konrad Rzeszutek <konradr@linux.vnet.ibm.com>
7  *  Copyright 2008
8  *  by Konrad Rzeszutek <ketuzsezr@darnok.org>
9  *
10  * This code finds the iSCSI Boot Format Table.
11  */
12 
13 #include <linux/memblock.h>
14 #include <linux/blkdev.h>
15 #include <linux/ctype.h>
16 #include <linux/device.h>
17 #include <linux/efi.h>
18 #include <linux/err.h>
19 #include <linux/init.h>
20 #include <linux/limits.h>
21 #include <linux/module.h>
22 #include <linux/pci.h>
23 #include <linux/stat.h>
24 #include <linux/string.h>
25 #include <linux/types.h>
26 #include <linux/acpi.h>
27 #include <linux/iscsi_ibft.h>
28 
29 #include <asm/mmzone.h>
30 
31 /*
32  * Physical location of iSCSI Boot Format Table.
33  */
34 struct acpi_table_ibft *ibft_addr;
35 EXPORT_SYMBOL_GPL(ibft_addr);
36 
37 static const struct {
38 	char *sign;
39 } ibft_signs[] = {
40 	{ "iBFT" },
41 	{ "BIFT" },	/* Broadcom iSCSI Offload */
42 };
43 
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 static int __init find_ibft_in_mem(void)
51 {
52 	unsigned long pos;
53 	unsigned int len = 0;
54 	void *virt;
55 	int i;
56 
57 	for (pos = IBFT_START; pos < IBFT_END; pos += 16) {
58 		/* The table can't be inside the VGA BIOS reserved space,
59 		 * so skip that area */
60 		if (pos == VGA_MEM)
61 			pos += VGA_SIZE;
62 		virt = isa_bus_to_virt(pos);
63 
64 		for (i = 0; i < ARRAY_SIZE(ibft_signs); i++) {
65 			if (memcmp(virt, ibft_signs[i].sign, IBFT_SIGN_LEN) ==
66 			    0) {
67 				unsigned long *addr =
68 				    (unsigned long *)isa_bus_to_virt(pos + 4);
69 				len = *addr;
70 				/* if the length of the table extends past 1M,
71 				 * the table cannot be valid. */
72 				if (pos + len <= (IBFT_END-1)) {
73 					ibft_addr = (struct acpi_table_ibft *)virt;
74 					pr_info("iBFT found at 0x%lx.\n", pos);
75 					goto done;
76 				}
77 			}
78 		}
79 	}
80 done:
81 	return len;
82 }
83 /*
84  * Routine used to find the iSCSI Boot Format Table. The logical
85  * kernel address is set in the ibft_addr global variable.
86  */
87 unsigned long __init find_ibft_region(unsigned long *sizep)
88 {
89 	ibft_addr = NULL;
90 
91 	/* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
92 	 * only use ACPI for this */
93 
94 	if (!efi_enabled(EFI_BOOT))
95 		find_ibft_in_mem();
96 
97 	if (ibft_addr) {
98 		*sizep = PAGE_ALIGN(ibft_addr->header.length);
99 		return (u64)virt_to_phys(ibft_addr);
100 	}
101 
102 	*sizep = 0;
103 	return 0;
104 }
105