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