// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Copyright 2007-2010 Red Hat, Inc.
 *  by Peter Jones <pjones@redhat.com>
 *  Copyright 2007 IBM, Inc.
 *  by Konrad Rzeszutek <konradr@linux.vnet.ibm.com>
 *  Copyright 2008
 *  by Konrad Rzeszutek <ketuzsezr@darnok.org>
 *
 * This code finds the iSCSI Boot Format Table.
 */

#include <linux/memblock.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.
 */
phys_addr_t ibft_phys_addr;
EXPORT_SYMBOL_GPL(ibft_phys_addr);

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

#define IBFT_SIGN_LEN 4
#define VGA_MEM 0xA0000 /* VGA buffer */
#define VGA_SIZE 0x20000 /* 128kB */

/*
 * Routine used to find and reserve the iSCSI Boot Format Table
 */
void __init reserve_ibft_region(void)
{
        unsigned long pos, virt_pos = 0;
        unsigned int len = 0;
        void *virt = NULL;
        int i;

        ibft_phys_addr = 0;

        /* iBFT 1.03 section 1.4.3.1 mandates that UEFI machines will
         * only use ACPI for this
         */
        if (efi_enabled(EFI_BOOT))
                return;

        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;

                /* Map page by page */
                if (offset_in_page(pos) == 0) {
                        if (virt)
                                early_memunmap(virt, PAGE_SIZE);
                        virt = early_memremap_ro(pos, PAGE_SIZE);
                        virt_pos = pos;
                }

                for (i = 0; i < ARRAY_SIZE(ibft_signs); i++) {
                        if (memcmp(virt + (pos - virt_pos), ibft_signs[i].sign,
                                   IBFT_SIGN_LEN) == 0) {
                                unsigned long *addr =
                                    (unsigned long *)(virt + pos - 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_phys_addr = pos;
                                        memblock_reserve(ibft_phys_addr, PAGE_ALIGN(len));
                                        pr_info("iBFT found at %pa.\n", &ibft_phys_addr);
                                        goto out;
                                }
                        }
                }
        }

out:
        early_memunmap(virt, PAGE_SIZE);
}