multiboot.c

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/*
 * support for Multiboot payloads
 *
 * Copyright (C) 2008 Robert Millan
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <cpu/x86/multiboot.h>
#include <string.h>
#include <device/resource.h>
#include <console/console.h>

typedef unsigned long long u64;

static struct multiboot_mmap_entry *mb_mem;
struct multiboot_info *mbi;

static struct {
        u64 addr;
        u64 len;
} reserved_mem[2];

static void build_mb_mem_range_nooverlap(u64 addr, u64 len)
{
        int i;
        for (i = 0; i < sizeof(reserved_mem) / sizeof(reserved_mem[0]); i++) {
                /* free region fully contained in reserved region, abort */
                if (addr >= reserved_mem[i].addr && addr + len <= reserved_mem[i].addr + reserved_mem[i].len)
                        return;
                /* reserved region splits free region */
                if (addr < reserved_mem[i].addr && addr + len > reserved_mem[i].addr + reserved_mem[i].len) {
                        build_mb_mem_range_nooverlap(addr, reserved_mem[i].addr - addr);
                        build_mb_mem_range_nooverlap(reserved_mem[i].addr + reserved_mem[i].len, (addr + len) - (reserved_mem[i].addr + reserved_mem[i].len));
                        return;
                }
                /* left overlap */
                if (addr < reserved_mem[i].addr + reserved_mem[i].len && addr + len > reserved_mem[i].addr + reserved_mem[i].len) {
                        len += addr;
                        addr = reserved_mem[i].addr + reserved_mem[i].len;
                        len -= addr;
                        /* len += addr - old_addr */
                        continue;
                }
                /* right overlap */
                if (addr < reserved_mem[i].addr && addr + len > reserved_mem[i].addr) {
                        len = reserved_mem[i].addr - addr;
                        continue;
                }
                /* none of the above, just add it */
        }

        mb_mem->addr = addr;
        mb_mem->len = len;
        mb_mem->type = 1;
        mb_mem->size = sizeof(*mb_mem) - sizeof(mb_mem->size);
        mb_mem++;
}

static void build_mb_mem_range(void *gp, struct device *dev, struct resource *res)
{
        build_mb_mem_range_nooverlap(res->base, res->size);
}

#define ROUND(_r,_a) ((_r) + (((_a) - 1)) & ~((_a) - 1))

unsigned long write_multiboot_info(
        unsigned long low_table_start, unsigned long low_table_end,
        unsigned long rom_table_start, unsigned long rom_table_end)
{
        struct multiboot_info *mbi;
        int i;

        mbi = rom_table_end;
        memset(mbi, 0, sizeof(*mbi));
        rom_table_end += sizeof(*mbi);

        mbi->mmap_addr = (u32) rom_table_end;
        mb_mem = rom_table_end;

        /* reserved regions */
        reserved_mem[0].addr = low_table_start;
        reserved_mem[0].len = ROUND(low_table_end - low_table_start, 4096);
        reserved_mem[1].addr = rom_table_start;
        reserved_mem[1].len = ROUND(rom_table_end - rom_table_start, 4096);

        for (i = 0; i < sizeof(reserved_mem) / sizeof(reserved_mem[0]); i++) {
                mb_mem->addr = reserved_mem[i].addr;
                mb_mem->len = reserved_mem[i].len;
                mb_mem->type = 2;
                mb_mem->size = sizeof(*mb_mem) - sizeof(mb_mem->size);
                mb_mem++;
        }

        /* free regions */
        search_global_resources( IORESOURCE_MEM | IORESOURCE_CACHEABLE,
                IORESOURCE_MEM | IORESOURCE_CACHEABLE, build_mb_mem_range, NULL);

        mbi->mmap_length = ((u32) mb_mem) - mbi->mmap_addr;
        mbi->flags |= MB_INFO_MEM_MAP;

        printk_info("Multiboot Information structure has been written.\n");

        return mb_mem;
}

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