drivers/firmware/iscsi_ibft_find.c

   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 }