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