drivers/firmware/iscsi_ibft_find.c

   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 static const struct {
  46         char *sign;
  47 } ibft_signs[] = {
  48 #ifdef CONFIG_ACPI
  49         /*
  50          * One spec says "IBFT", the other says "iBFT". We have to check
  51          * for both.
  52          */
  53         { ACPI_SIG_IBFT },
  54 #endif
  55         { "iBFT" },
  56         { "BIFT" },     /* Broadcom iSCSI Offload */
  57 };
  58
  59 #define IBFT_SIGN_LEN 4
  60 #define IBFT_START 0x80000 /* 512kB */
  61 #define IBFT_END 0x100000 /* 1MB */
  62 #define VGA_MEM 0xA0000 /* VGA buffer */
  63 #define VGA_SIZE 0x20000 /* 128kB */
  64
  65 #ifdef CONFIG_ACPI
  66 static int __init acpi_find_ibft(struct acpi_table_header *header)
  67 {
  68         ibft_addr = (struct acpi_table_ibft *)header;
  69         return 0;
  70 }
  71 #endif /* CONFIG_ACPI */
  72
  73 static int __init find_ibft_in_mem(void)
  74 {
  75         unsigned long pos;
  76         unsigned int len = 0;
  77         void *virt;
  78         int i;
  79
  80         for (pos = IBFT_START; pos < IBFT_END; pos += 16) {
  81                 /* The table can't be inside the VGA BIOS reserved space,
  82                  * so skip that area */
  83                 if (pos == VGA_MEM)
  84                         pos += VGA_SIZE;
  85                 virt = isa_bus_to_virt(pos);
  86
  87                 for (i = 0; i < ARRAY_SIZE(ibft_signs); i++) {
  88                         if (memcmp(virt, ibft_signs[i].sign, IBFT_SIGN_LEN) ==
  89                             0) {
  90                                 unsigned long *addr =
  91                                     (unsigned long *)isa_bus_to_virt(pos + 4);
  92                                 len = *addr;
  93                                 /* if the length of the table extends past 1M,
  94                                  * the table cannot be valid. */
  95                                 if (pos + len <= (IBFT_END-1)) {
  96                                         ibft_addr = (struct acpi_table_ibft *)virt;
  97                                         goto done;
  98                                 }
  99                         }
 100                 }
 101         }
 102 done:
 103         return len;
 104 }
 105 /*
 106  * Routine used to find the iSCSI Boot Format Table. The logical
 107  * kernel address is set in the ibft_addr global variable.
 108  */
 109 unsigned long __init find_ibft_region(unsigned long *sizep)
 110 {
 111 #ifdef CONFIG_ACPI
 112         int i;
 113 #endif
 114         ibft_addr = NULL;
 115
 116 #ifdef CONFIG_ACPI
 117         for (i = 0; i < ARRAY_SIZE(ibft_signs) && !ibft_addr; i++)
 118                 acpi_table_parse(ibft_signs[i].sign, acpi_find_ibft);
 119 #endif /* CONFIG_ACPI */
 120
 121         /* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
 122          * only use ACPI for this */
 123
 124         if (!ibft_addr && !efi_enabled)
 125                 find_ibft_in_mem();
 126
 127         if (ibft_addr) {
 128                 *sizep = PAGE_ALIGN(ibft_addr->header.length);
 129                 return (u64)isa_virt_to_bus(ibft_addr);
 130         }
 131
 132         *sizep = 0;
 133         return 0;
 134 }