iscsi_ibft_find.c

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/*
 *  Copyright 2007-2010 Red Hat, Inc.
 *  by Peter Jones <[email protected]>
 *  Copyright 2007 IBM, Inc.
 *  by Konrad Rzeszutek <[email protected]>
 *  Copyright 2008
 *  by Konrad Rzeszutek <[email protected]>
 *
 * This code finds the iSCSI Boot Format Table.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License v2.0 as published by
 * the Free Software Foundation
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/bootmem.h>
#include <linux/blkdev.h>
#include <linux/ctype.h>
#include <linux/device.h>
#include <linux/efi.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/limits.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/acpi.h>
#include <linux/iscsi_ibft.h>

#include <asm/mmzone.h>

/*
 * Physical location of iSCSI Boot Format Table.
 */
struct acpi_table_ibft *ibft_addr;
EXPORT_SYMBOL_GPL(ibft_addr);

static const struct {
    char *sign;
} ibft_signs[] = {
    { "iBFT" },
    { "BIFT" }, /* Broadcom iSCSI Offload */
};

#define IBFT_SIGN_LEN 4
#define IBFT_START 0x80000 /* 512kB */
#define IBFT_END 0x100000 /* 1MB */
#define VGA_MEM 0xA0000 /* VGA buffer */
#define VGA_SIZE 0x20000 /* 128kB */

static int __init find_ibft_in_mem(void)
{
    unsigned long pos;
    unsigned int len = 0;
    void *virt;
    int i;

    for (pos = IBFT_START; pos < IBFT_END; pos += 16) {
        /* The table can't be inside the VGA BIOS reserved space,
         * so skip that area */
        if (pos == VGA_MEM)
            pos += VGA_SIZE;
        virt = isa_bus_to_virt(pos);

        for (i = 0; i < ARRAY_SIZE(ibft_signs); i++) {
            if (memcmp(virt, ibft_signs[i].sign, IBFT_SIGN_LEN) ==
                0) {
                unsigned long *addr =
                    (unsigned long *)isa_bus_to_virt(pos + 4);
                len = *addr;
                /* if the length of the table extends past 1M,
                 * the table cannot be valid. */
                if (pos + len <= (IBFT_END-1)) {
                    ibft_addr = (struct acpi_table_ibft *)virt;
                    pr_info("iBFT found at 0x%lx.\n", pos);
                    goto done;
                }
            }
        }
    }
done:
    return len;
}
/*
 * Routine used to find the iSCSI Boot Format Table. The logical
 * kernel address is set in the ibft_addr global variable.
 */
unsigned long __init find_ibft_region(unsigned long *sizep)
{
    ibft_addr = NULL;

    /* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
     * only use ACPI for this */

    if (!efi_enabled)
        find_ibft_in_mem();

    if (ibft_addr) {
        *sizep = PAGE_ALIGN(ibft_addr->header.length);
        return (u64)isa_virt_to_bus(ibft_addr);
    }

    *sizep = 0;
    return 0;
}