//----------------------------------------------------------------------------//
//                           GNU GPL OS/K                                     //
//                                                                            //
//  Desc:       ACPI, Hardware detection related functions                    //
//                                                                            //
//                                                                            //
//  Copyright © 2018-2020 The OS/K Team                                       //
//                                                                            //
//  This file is part of OS/K.                                                //
//                                                                            //
//  OS/K 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 3 of the License, or         //
//  any later version.                                                        //
//                                                                            //
//  OS/K 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 OS/K.  If not, see <https://www.gnu.org/licenses/>.            //
//----------------------------------------------------------------------------//

#include <init/boot.h>
#include <io/vga.h>
#include <io/acpi.h>
#include <mm/paging.h>
#include <mm/map.h>

char IoACPIVersion = 1;
int tableCount = 1;

extern MemoryMap_t memoryMap;

// ACPI reverse strings
static char *SDTChar[N_SDT_TYPES] = {
    "APIC",
    "BERT",
    "CPEP",
    "DSDT",
    "ECDT",
    "EINJ",
    "ERST",
    "FACP",
    "FACS",
    "HEST",
    "MSCT",
    "MPST",
    "OEMx",
    "PMTT",
    "PSDT",
    "RASF",
    "RSDT",
    "SBST",
    "SLIT",
    "SRAT",
    "SSDT",
    "XSDT",
    "HPET",
    "MCFG"
};

// ACPI Tables Directory
static SDTHeader_t *SDTDirectory[N_SDT_TYPES] = {0};

//
// Returns the checksum of the given structure
//
static char DoChecksum(const void *ptr, const size_t size,
                         size_t intermediateSize, ulong reason)
{
    char checksum = 0;
    for (ulong i=0; i < (ulong)size; i++) {
        if (reason && i > (ulong)intermediateSize)
            break;
        checksum += (uchar)((char*)ptr)[i];
    }
    return checksum;
}

//
// Returns the address of the RSDP
//
static inline RSDPDescriptor_t *IoFindRSDP()
{
    char *rsdp = NULL;


    // Search in EBDA
    for (rsdp = (char *)0x00080000;   // EBDA address
         (ulong)rsdp < (ulong)0x0009FFFF;             // EBDA end
         rsdp++) {

            if (!strncmp(rsdp, "RSD PTR", 6)) {
                return (RSDPDescriptor_t *)rsdp;
            }
        }

    // Search in BDA
    for (rsdp = (char *)0x000E0000;   // BDA address
         (ulong)rsdp < (ulong)0x000FFFFF;             // BDA end
         rsdp++) {

            if (!strncmp(rsdp, "RSD PTR", 6)) {
                return (RSDPDescriptor_t *)rsdp;
            }
        }

    return NULL;
}

//
// RSDP Exploration
//
static inline void IoInitRSDP(void)
{
    char checksum = 1;

    RSDPDescriptor_t *rsdp = IoFindRSDP();
    if (!rsdp)
        KeStartPanic("ACPI RSDP not found in memory");

    // Checksum calculation
    checksum = DoChecksum(rsdp, (size_t)sizeof(RSDPDescriptor_t),
                          (size_t)sizeof(struct RSDPLegacy),
                          !rsdp->legacy.revision
                          );

    if (checksum)
        KeStartPanic("Invalid RSDP checksum : %d vs 0", checksum);

    if (rsdp->legacy.revision == 1 || rsdp->legacy.revision >= 3)
        KeStartPanic("Invalid ACPI Revision : %d", rsdp->legacy.revision);

    DebugLog("ACPI Revision %d (OEM %s)\n",
            (uint)rsdp->legacy.revision,
            rsdp->legacy.OEMID
            );

    SDTDirectory[SDT_RSDT] = (void *)(ulong)rsdp->legacy.rsdtAddress;

    if (rsdp->legacy.revision) {
        SDTDirectory[SDT_XSDT] = (void *)rsdp->xsdtAddress;
        IoACPIVersion = 2;
    }
}

//
// R/XSDT Exploration
//
static inline void IoInitRXSDT(void)
{
    char checksum = 1;

    SDTHeader_t *rxsdt = SDTDirectory[SDT_RSDT];

    if (IoACPIVersion == 2) {
        rxsdt = SDTDirectory[SDT_XSDT];
    }

    /* // Checksum calculation */
    checksum = DoChecksum(rxsdt, (size_t)rxsdt->length,
                          0,
                          0
                          );

    if (checksum)
        KeStartPanic("Invalid RSDT checksum : %d vs 0", checksum);

    if (IoACPIVersion == 1) {
        DebugLog("ACPI Root System Table %s (%s) length %d [%p]\n",
            rxsdt->signature,
            rxsdt->OEMID,
            rxsdt->length,
            rxsdt
            );
    } else {
        DebugLog("ACPI Extended System Table %s (%s) length %d [%p]\n",
            rxsdt->signature,
            rxsdt->OEMID,
            rxsdt->length,
            rxsdt
            );
    }
}

//
// Returns the address of the MCFG
//
static inline SDTHeader_t *IoFindMCFG()
{
    char *mcfg = NULL;

    for (uint i = 0; i < memoryMap.length; i++) {
        if (memoryMap.entry[i].type == RESERVED_ZONE) {

            for (mcfg = (char *)memoryMap.entry[i].addr;
              (ulong)mcfg < (ulong)(memoryMap.entry[i].addr +
                                   memoryMap.entry[i].length);
              mcfg++) {

                if (!strncmp(mcfg, "MCFG", 3)) {
                    return (SDTHeader_t *)mcfg;
                }
            }
        }
    }

    return NULL;
}

//
// Explore all ACPI Tables
//
static inline void IoSearchAcpiTables(void)
{
    SDTHeader_t *xrsdt = SDTDirectory[SDT_RSDT];
    SDTHeader_t *table = NULL;
    uint *curInt = NULL;
    ulong *curLong = NULL;
    register char checksum;
    int entries;

    if (IoACPIVersion == 1) {
        entries = (xrsdt->length - sizeof(xrsdt)) / 4;
    } else {
        xrsdt = SDTDirectory[SDT_XSDT];
        entries = (xrsdt->length - sizeof(xrsdt)) / 8;
    }

    DebugLog("ACPI detected %d entries\n", entries);

    curInt = (uint*)&(xrsdt->sdtEntry);
    curLong = (ulong*)&(xrsdt->sdtEntry);

    // Parsing R/XSDT
    for (int i = 0; i < entries; i++) {

        if (IoACPIVersion == 1)
            table = (SDTHeader_t *)(ulong)curInt[i];
        else
            table = (SDTHeader_t *)(ulong)curLong[i];

        //KernLog("\tACPI RSDT[%d] %p\n", i, table);
        if (MmIsBusyZone(table)) {
            checksum = DoChecksum(table, (size_t)table->length, 0, 0);
            if (!checksum) {
                for (ulong i=0; i < N_SDT_TYPES; i++) {
                    if (!strncmp(table->signature, SDTChar[i], 3)) {
                        DebugLog("ACPI System Table %s (OEM %s) length %d [%p]\n",
                            SDTChar[i],
                            table->OEMID,
                            table->length,
                            table
                        );
                        SDTDirectory[i] = table;
                    }
                }
            }
        }
    }

    // Parsing FADT
    FADT_t *fadt = (FADT_t *)IoGetAcpiTable(SDT_FADT);
    SDTHeader_t *dsdt;

    if (IoACPIVersion == 1) {
        dsdt = (SDTHeader_t *)(ulong)fadt->dsdtAddress;
    } else {
        dsdt = (SDTHeader_t *)(ulong)fadt->xDsdtAddress;
    }

    checksum = DoChecksum(dsdt, (size_t)dsdt->length, 0, 0);
    if (!checksum) {
        if (!strncmp(dsdt->signature, SDTChar[SDT_DSDT], 3)) {
                DebugLog("ACPI System Table %s (OEM %s) length %d [%p]\n",
                    SDTChar[SDT_DSDT],
                    dsdt->OEMID,
                    dsdt->length,
                    dsdt
                );
                SDTDirectory[SDT_DSDT] = dsdt;
        }
    }

    // Finding MCFG
    SDTHeader_t *mcfg = IoFindMCFG();

    if (mcfg) {
        //DebugLog("MCFG found at %p\n");
        checksum = 0; //DoChecksum(mcfg, (size_t)mcfg->length, 0, 0);
        if (!checksum) {
            if (!strncmp(mcfg->signature, SDTChar[SDT_MCFG], 3)) {
                    DebugLog("ACPI System Table %s (OEM %s) length %lu [%p]\n",
                        mcfg->signature,
                        mcfg->OEMID,
                        mcfg->length / MB,
                        mcfg
                    );
                    SDTDirectory[SDT_MCFG] = mcfg;
            }
        }
    }
}

// -------------------------------------------------------------------------- //

//
// Initialise the ACPI by finding tables
//
void IoInitAcpi(void)
{
    // MAP ACPI PAGES

    for (uint i = 0; i < memoryMap.length; i++) {
        if (memoryMap.entry[i].type != AVAILABLE_ZONE) {

            // Map each page that is in the busy zone
            for (uint j = 0;
                 j < (memoryMap.entry[i].length
                    + ((ulong)memoryMap.entry[i].addr)
                         - ((ulong)memoryMap.entry[i].addr
                            & 0xFFFFFFFFFFFFF000))
                    / KPAGESIZE;
                 j++) {
                    MmMapPage(memoryMap.entry[i].addr + KPAGESIZE*j,
                              memoryMap.entry[i].addr + KPAGESIZE*j,
                              PRESENT);
                    //KernLog("ACPI %d ID MAP %p\n", i,
                    //        memoryMap.entry[i].addr + KPAGESIZE*j);
                }
        }
    }

    // FIND RSDP
    IoInitRSDP();

    IoInitRXSDT();

    IoSearchAcpiTables();
}

// -------------------------------------------------------------------------- //

//
// Returns the addr of the submitted SDT
//
//  Arg must be a member of the enum in acpi.h
//
SDTHeader_t *IoGetAcpiTable(ulong id)
{
    return SDTDirectory[id];
}