drivers/firmware/iscsi_ibft_find.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  *  Copyright 2007-2010 Red Hat, Inc.
0004  *  by Peter Jones <pjones@redhat.com>
0005  *  Copyright 2007 IBM, Inc.
0006  *  by Konrad Rzeszutek <konradr@linux.vnet.ibm.com>
0007  *  Copyright 2008
0008  *  by Konrad Rzeszutek <ketuzsezr@darnok.org>
0009  *
0010  * This code finds the iSCSI Boot Format Table.
0011  */
0012
0013 #include <linux/memblock.h>
0014 #include <linux/blkdev.h>
0015 #include <linux/ctype.h>
0016 #include <linux/device.h>
0017 #include <linux/efi.h>
0018 #include <linux/err.h>
0019 #include <linux/init.h>
0020 #include <linux/limits.h>
0021 #include <linux/module.h>
0022 #include <linux/pci.h>
0023 #include <linux/stat.h>
0024 #include <linux/string.h>
0025 #include <linux/types.h>
0026 #include <linux/acpi.h>
0027 #include <linux/iscsi_ibft.h>
0028
0029 #include <asm/mmzone.h>
0030
0031 /*
0032  * Physical location of iSCSI Boot Format Table.
0033  */
0034 phys_addr_t ibft_phys_addr;
0035 EXPORT_SYMBOL_GPL(ibft_phys_addr);
0036
0037 static const struct {
0038     char *sign;
0039 } ibft_signs[] = {
0040     { "iBFT" },
0041     { "BIFT" }, /* Broadcom iSCSI Offload */
0042 };
0043
0044 #define IBFT_SIGN_LEN 4
0045 #define IBFT_START 0x80000 /* 512kB */
0046 #define IBFT_END 0x100000 /* 1MB */
0047 #define VGA_MEM 0xA0000 /* VGA buffer */
0048 #define VGA_SIZE 0x20000 /* 128kB */
0049
0050 /*
0051  * Routine used to find and reserve the iSCSI Boot Format Table
0052  */
0053 void __init reserve_ibft_region(void)
0054 {
0055     unsigned long pos;
0056     unsigned int len = 0;
0057     void *virt;
0058     int i;
0059
0060     ibft_phys_addr = 0;
0061
0062     /* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
0063      * only use ACPI for this
0064      */
0065     if (efi_enabled(EFI_BOOT))
0066         return;
0067
0068     for (pos = IBFT_START; pos < IBFT_END; pos += 16) {
0069         /* The table can't be inside the VGA BIOS reserved space,
0070          * so skip that area */
0071         if (pos == VGA_MEM)
0072             pos += VGA_SIZE;
0073         virt = isa_bus_to_virt(pos);
0074
0075         for (i = 0; i < ARRAY_SIZE(ibft_signs); i++) {
0076             if (memcmp(virt, ibft_signs[i].sign, IBFT_SIGN_LEN) ==
0077                 0) {
0078                 unsigned long *addr =
0079                     (unsigned long *)isa_bus_to_virt(pos + 4);
0080                 len = *addr;
0081                 /* if the length of the table extends past 1M,
0082                  * the table cannot be valid. */
0083                 if (pos + len <= (IBFT_END-1)) {
0084                     ibft_phys_addr = pos;
0085                     memblock_reserve(ibft_phys_addr, PAGE_ALIGN(len));
0086                     pr_info("iBFT found at %pa.\n", &ibft_phys_addr);
0087                     return;
0088                 }
0089             }
0090         }
0091     }
0092 }