/*      $OpenBSD: memprobe.c,v 1.20 2024/11/18 02:32:22 mlarkin Exp $   */

/*
 * Copyright (c) 1997-1999 Michael Shalayeff
 * Copyright (c) 1997-1999 Tobias Weingartner
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#include <sys/param.h>
#include <machine/biosvar.h>
#include <dev/isa/isareg.h>
#include <stand/boot/bootarg.h>
#include "libsa.h"

u_int cnvmem, extmem;           /* XXX - compatibility */

bios_memmap_t bios_memmap[64];  /* This is easier */

/*
 * Check gateA20
 *
 * A sanity check.
 */
static __inline int
checkA20(void)
{
        register char *p = (char *)0x100000;
        register char *q = (char *)0x000000;
        int st;

        /* Simple check */
        if (*p != *q)
                return 1;

        /* Complex check */
        *p = ~(*p);
        st = (*p != *q);
        *p = ~(*p);

        return st;
}

/*
 * BIOS int 15, AX=E820
 *
 * This is the "preferred" method.
 */
static __inline bios_memmap_t *
bios_E820(bios_memmap_t *mp)
{
        int rc, off = 0, sig, gotcha = 0;

        do {
                BIOS_regs.biosr_es = ((u_int)(mp) >> 4);
                __asm volatile(DOINT(0x15) "; setc %b1"
                    : "=a" (sig), "=d" (rc), "=b" (off)
                    : "0" (0xE820), "1" (0x534d4150), "b" (off),
                      "c" (sizeof(*mp)), "D" (((u_int)mp) & 0xf)
                    : "cc", "memory");
                off = BIOS_regs.biosr_bx;

                if (rc & 0xff || sig != 0x534d4150)
                        break;
                gotcha++;
                if (!mp->type)
                        mp->type = BIOS_MAP_RES;
                mp++;
        } while (off);

        if (!gotcha)
                return NULL;
#ifdef DEBUG
        printf("0x15[E820] ");
#endif
        return mp;
}

/*
 * BIOS int 15, AX=8800
 *
 * Only used if int 15, AX=E820 does not work.
 * Machines with this are restricted to 64MB.
 */
static __inline bios_memmap_t *
bios_8800(bios_memmap_t *mp)
{
        int rc, mem;

        __asm volatile(DOINT(0x15) "; setc %b0"
            : "=c" (rc), "=a" (mem) : "a" (0x8800));

        if (rc & 0xff)
                return NULL;
#ifdef DEBUG
        printf("0x15[8800] ");
#endif
        /* Fill out a BIOS_MAP */
        mp->addr = 1024 * 1024;         /* 1MB */
        mp->size = (mem & 0xffff) * 1024;
        mp->type = BIOS_MAP_FREE;

        return ++mp;
}

/*
 * BIOS int 0x12 Get Conventional Memory
 *
 * Only used if int 15, AX=E820 does not work.
 */
static __inline bios_memmap_t *
bios_int12(bios_memmap_t *mp)
{
        int mem;
#ifdef DEBUG
        printf("0x12 ");
#endif
        __asm volatile(DOINT(0x12) : "=a" (mem) :: "%ecx", "%edx", "cc");

        /* Fill out a bios_memmap_t */
        mp->addr = 0;
        mp->size = (mem & 0xffff) * 1024;
        mp->type = BIOS_MAP_FREE;

        return ++mp;
}

/*
 * addrprobe(kloc): Probe memory at address kloc * 1024.
 *
 * This is a hack, but it seems to work ok.  Maybe this is
 * the *real* way that you are supposed to do probing???
 *
 * Modify the original a bit.  We write everything first, and
 * then test for the values.  This should croak on machines that
 * return values just written on non-existent memory...
 *
 * BTW: These machines are pretty broken IMHO.
 *
 * XXX - Does not detect aliased memory.
 */
const u_int addrprobe_pat[] = {
        0x00000000, 0xFFFFFFFF,
        0x01010101, 0x10101010,
        0x55555555, 0xCCCCCCCC
};
static int
addrprobe(u_int kloc)
{
        volatile u_int *loc;
        register u_int i, ret = 0;
        u_int save[nitems(addrprobe_pat)];

        /* Get location */
        loc = (int *)(intptr_t)(kloc * 1024);

        save[0] = *loc;
        /* Probe address */
        for (i = 0; i < nitems(addrprobe_pat); i++) {
                *loc = addrprobe_pat[i];
                if (*loc != addrprobe_pat[i])
                        ret++;
        }
        *loc = save[0];

        if (!ret) {
                /* Write address */
                for (i = 0; i < nitems(addrprobe_pat); i++) {
                        save[i] = loc[i];
                        loc[i] = addrprobe_pat[i];
                }

                /* Read address */
                for (i = 0; i < nitems(addrprobe_pat); i++) {
                        if (loc[i] != addrprobe_pat[i])
                                ret++;
                        loc[i] = save[i];
                }
        }

        return ret;
}

/*
 * Probe for all extended memory.
 *
 * This is only used as a last resort.  If we resort to this
 * routine, we are getting pretty desperate.  Hopefully nobody
 * has to rely on this after all the work above.
 *
 * XXX - Does not detect aliased memory.
 * XXX - Could be destructive, as it does write.
 */
static __inline bios_memmap_t *
badprobe(bios_memmap_t *mp)
{
        u_int64_t ram;
#ifdef DEBUG
        printf("scan ");
#endif
        /*
         * probe extended memory
         *
         * There is no need to do this in assembly language.  This is
         * much easier to debug in C anyways.
         */
        for (ram = 1024; ram < 512 * 1024; ram += 4)
                if (addrprobe(ram))
                        break;

        mp->addr = 1024 * 1024;
        mp->size = (ram - 1024) * 1024;
        mp->type = BIOS_MAP_FREE;

        return ++mp;
}

void
memprobe(void)
{
        bios_memmap_t *pm = bios_memmap, *im;

#ifdef DEBUG
        printf(" mem(");
#else
        printf(" mem[");
#endif

        if ((pm = bios_E820(bios_memmap)) == NULL) {
                im = bios_int12(bios_memmap);
                pm = bios_8800(im);
                if (pm == NULL)
                        pm = badprobe(im);
                if (pm == NULL) {
                        printf(" No Extended memory detected.");
                        pm = im;
                }
        }
        pm->type = BIOS_MAP_END;

        /* XXX - gotta peephole optimize the list */

#ifdef DEBUG
        printf(")[");
#endif

        /* XXX - Compatibility, remove later (smpprobe() relies on it) */
        extmem = cnvmem = 0;
        for (im = bios_memmap; im->type != BIOS_MAP_END; im++) {
                /* Count only "good" memory chunks 12K and up in size */
                if ((im->type == BIOS_MAP_FREE) && (im->size >= 12 * 1024)) {
                        if (im->size > 1024 * 1024)
                                printf("%uM ", (u_int)(im->size /
                                    (1024 * 1024)));
                        else
                                printf("%uK ", (u_int)im->size / 1024);

                        /*
                         * Compute compatibility values:
                         * cnvmem -- is the upper boundary of conventional
                         *      memory (below IOM_BEGIN (=640k))
                         * extmem -- is the size of the contiguous extended
                         *      memory segment starting at 1M
                         *
                         * We ignore "good" memory in the 640K-1M hole.
                         * We drop "machine {cnvmem,extmem}" commands.
                         */
                        if (im->addr < IOM_BEGIN)
                                cnvmem = max(cnvmem,
                                    im->addr + im->size) / 1024;
                        if (im->addr >= IOM_END &&
                            (im->addr / 1024) == (extmem + 1024))
                                extmem += im->size / 1024;
                }
        }

        /*
         * Adjust extmem to be no more than 4G (which it usually is not
         * anyways).  In order for an x86 type machine (amd64/etc) to use
         * more than 4GB of memory, it will need to grok and use the bios
         * memory map we pass it.  Note that above we only count CONTIGUOUS
         * memory from the 1MB boundary on for extmem (think I/O holes).
         *
         * extmem is in KB, and we have 4GB - 1MB (base/io hole) worth of it.
         */
        if (extmem > 4 * 1024 * 1024 - 1024)
                extmem = 4 * 1024 * 1024 - 1024;

        /* Check if gate A20 is on */
        printf("a20=o%s] ", checkA20()? "n" : "ff!");
}

void
dump_biosmem(bios_memmap_t *tm)
{
        register bios_memmap_t *p;
        register u_int total = 0;

        if (tm == NULL)
                tm = bios_memmap;

        for (p = tm; p->type != BIOS_MAP_END; p++) {
                printf("Region %ld: type %u at 0x%llx for %uKB\n",
                    (long)(p - tm), p->type, p->addr,
                    (u_int)(p->size / 1024));

                if (p->type == BIOS_MAP_FREE)
                        total += p->size / 1024;
        }

        printf("Low ram: %dKB  High ram: %dKB\n", cnvmem, extmem);
        printf("Total free memory: %uKB\n", total);
}

int
mem_limit(long long ml)
{
        register bios_memmap_t *p;

        for (p = bios_memmap; p->type != BIOS_MAP_END; p++) {
                register int64_t sp = p->addr, ep = p->addr + p->size;

                if (p->type != BIOS_MAP_FREE)
                        continue;

                /* Wholly above limit, nuke it */
                if ((sp >= ml) && (ep >= ml)) {
                        bcopy (p + 1, p, (char *)bios_memmap +
                               sizeof(bios_memmap) - (char *)p);
                } else if ((sp < ml) && (ep >= ml)) {
                        p->size -= (ep - ml);
                }
        }
        return 0;
}

int
mem_delete(long long sa, long long ea)
{
        register bios_memmap_t *p;

        for (p = bios_memmap; p->type != BIOS_MAP_END; p++) {
                if (p->type == BIOS_MAP_FREE) {
                        register int64_t sp = p->addr, ep = p->addr + p->size;

                        /* can we eat it as a whole? */
                        if ((sa - sp) <= PAGE_SIZE && (ep - ea) <= PAGE_SIZE) {
                                bcopy(p + 1, p, (char *)bios_memmap +
                                    sizeof(bios_memmap) - (char *)p);
                                break;
                        /* eat head or legs */
                        } else if (sa <= sp && sp < ea) {
                                p->addr = ea;
                                p->size = ep - ea;
                                break;
                        } else if (sa < ep && ep <= ea) {
                                p->size = sa - sp;
                                break;
                        } else if (sp < sa && ea < ep) {
                                /* bite in half */
                                bcopy(p, p + 1, (char *)bios_memmap +
                                    sizeof(bios_memmap) - (char *)p -
                                    sizeof(bios_memmap[0]));
                                p[1].addr = ea;
                                p[1].size = ep - ea;
                                p->size = sa - sp;
                                break;
                        }
                }
        }
        return 0;
}

int
mem_add(long long sa, long long ea)
{
        register bios_memmap_t *p;

        for (p = bios_memmap; p->type != BIOS_MAP_END; p++) {
                if (p->type == BIOS_MAP_FREE) {
                        register int64_t sp = p->addr, ep = p->addr + p->size;

                        /* is it already there? */
                        if (sp <= sa && ea <= ep) {
                                break;
                        /* join head or legs */
                        } else if (sa < sp && sp <= ea) {
                                p->addr = sa;
                                p->size = ep - sa;
                                break;
                        } else if (sa <= ep && ep < ea) {
                                p->size = ea - sp;
                                break;
                        } else if (ea < sp) {
                                /* insert before */
                                bcopy(p, p + 1, (char *)bios_memmap +
                                    sizeof(bios_memmap) - (char *)(p - 1));
                                p->addr = sa;
                                p->size = ea - sa;
                                break;
                        }
                }
        }

        /* meaning add new item at the end of the list */
        if (p->type == BIOS_MAP_END) {
                p[1] = p[0];
                p->type = BIOS_MAP_FREE;
                p->addr = sa;
                p->size = ea - sa;
        }

        return 0;
}

void
mem_pass(void)
{
        bios_memmap_t *p;

        for (p = bios_memmap; p->type != BIOS_MAP_END; p++)
                ;
        addbootarg(BOOTARG_MEMMAP, (p - bios_memmap + 1) * sizeof *bios_memmap,
            bios_memmap);
}