drivers/firmware/iscsi_ibft_find.c

   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/stat.h>
  31 #include <linux/string.h>
  32 #include <linux/types.h>
  33
  34 #include <asm/mmzone.h>
  35
  36 /*
  37  * Physical location of iSCSI Boot Format Table.
  38  */
  39 struct ibft_table_header *ibft_addr;
  40 EXPORT_SYMBOL_GPL(ibft_addr);
  41
  42 #define IBFT_SIGN "iBFT"
  43 #define IBFT_SIGN_LEN 4
  44 #define IBFT_START 0x80000 /* 512kB */
  45 #define IBFT_END 0x100000 /* 1MB */
  46 #define VGA_MEM 0xA0000 /* VGA buffer */
  47 #define VGA_SIZE 0x20000 /* 128kB */
  48
  49
  50 /*
  51  * Routine used to find the iSCSI Boot Format Table. The logical
  52  * kernel address is set in the ibft_addr global variable.
  53  */
  54 unsigned long __init find_ibft_region(unsigned long *sizep)
  55 {
  56         unsigned long pos;
  57         unsigned int len = 0;
  58         void *virt;
  59
  60         ibft_addr = NULL;
  61
  62         for (pos = IBFT_START; pos < IBFT_END; pos += 16) {
  63                 /* The table can't be inside the VGA BIOS reserved space,
  64                  * so skip that area */
  65                 if (pos == VGA_MEM)
  66                         pos += VGA_SIZE;
  67                 virt = isa_bus_to_virt(pos);
  68                 if (memcmp(virt, IBFT_SIGN, IBFT_SIGN_LEN) == 0) {
  69                         unsigned long *addr =
  70                             (unsigned long *)isa_bus_to_virt(pos + 4);
  71                         len = *addr;
  72                         /* if the length of the table extends past 1M,
  73                          * the table cannot be valid. */
  74                         if (pos + len <= (IBFT_END-1)) {
  75                                 ibft_addr = (struct ibft_table_header *)virt;
  76                                 break;
  77                         }
  78                 }
  79         }
  80         if (ibft_addr) {
  81                 *sizep = PAGE_ALIGN(len);
  82                 return pos;
  83         }
  84
  85         *sizep = 0;
  86         return 0;
  87 }