/*
 * Copyright 2020 Haiku, Inc. All rights reserved.
 * Copyright 2014, Jessica Hamilton, jessica.l.hamilton@gmail.com.
 * Copyright 2011, Rene Gollent, rene@gollent.com.
 * Copyright 2008, Dustin Howett, dustin.howett@gmail.com. All rights reserved.
 * Copyright 2007, Michael Lotz, mmlr@mlotz.ch
 * Copyright 2004-2005, Axel Dörfler, axeld@pinc-software.de.
 * Distributed under the terms of the MIT License.
 *
 * Copyright 2001, Travis Geiselbrecht. All rights reserved.
 * Distributed under the terms of the NewOS License.
*/


#include <string.h>

#include <KernelExport.h>
#include <SupportDefs.h>

#include <arch_acpi.h>
#include <boot/stage2.h>
#include <boot/platform.h>
#include <boot/stdio.h>

#include "efi_platform.h"
#include "acpi.h"
#include "mmu.h"


#define TRACE_ACPI
#ifdef TRACE_ACPI
#       define TRACE(x) dprintf x
#else
#       define TRACE(x) ;
#endif


static acpi_descriptor_header* sAcpiRsdt; // System Description Table
static acpi_descriptor_header* sAcpiXsdt; // Extended System Description Table
static int32 sNumEntries = -1;


static status_t
acpi_validate_rsdp(acpi_rsdp* rsdp)
{
        const char* data = (const char*)rsdp;
        unsigned char checksum = 0;
        for (uint32 i = 0; i < sizeof(acpi_rsdp_legacy); i++)
                checksum += data[i];

        if ((checksum & 0xff) != 0) {
                TRACE(("acpi: rsdp failed basic checksum\n"));
                return B_BAD_DATA;
        }

        // for ACPI 2.0+ we need to also validate the extended checksum
        if (rsdp->revision > 0) {
                for (uint32 i = sizeof(acpi_rsdp_legacy);
                        i < sizeof(acpi_rsdp_extended); i++) {
                                checksum += data[i];
                }

                if ((checksum & 0xff) != 0) {
                        TRACE(("acpi: rsdp failed extended checksum\n"));
                        return B_BAD_DATA;
                }
        }

        return B_OK;
}


static status_t
acpi_validate_rsdt(acpi_descriptor_header* rsdt)
{
        const char* data = (const char*)rsdt;
        unsigned char checksum = 0;
        for (uint32 i = 0; i < rsdt->length; i++)
                checksum += data[i];

        return checksum == 0 ? B_OK : B_BAD_DATA;
}


static status_t
acpi_check_rsdt(acpi_rsdp* rsdp)
{
        if (acpi_validate_rsdp(rsdp) != B_OK)
                return B_BAD_DATA;

        bool usingXsdt = false;

        TRACE(("acpi: found rsdp at %p oem id: %.6s, rev %d\n",
                rsdp, rsdp->oem_id, rsdp->revision));
        TRACE(("acpi: rsdp points to rsdt at 0x%" B_PRIx32 "\n", rsdp->rsdt_address));

        acpi_descriptor_header* rsdt = NULL;
        if (rsdp->revision > 0) {
                rsdt = (acpi_descriptor_header*)(addr_t)rsdp->xsdt_address;
                if (rsdt != NULL
                        && strncmp(rsdt->signature, ACPI_XSDT_SIGNATURE, 4) != 0) {
                        rsdt = NULL;
                        TRACE(("acpi: invalid extended system description table\n"));
                } else
                        usingXsdt = true;
        }

        // if we're ACPI v1 or we fail to map the XSDT for some reason,
        // attempt to use the RSDT instead.
        if (rsdt == NULL) {
                // validate the root system description table
                rsdt = (acpi_descriptor_header*)(addr_t)rsdp->rsdt_address;
                if (rsdt == NULL) {
                        TRACE(("acpi: couldn't map rsdt header\n"));
                        return B_ERROR;
                }
                if (strncmp(rsdt->signature, ACPI_RSDT_SIGNATURE, 4) != 0) {
                        rsdt = NULL;
                        TRACE(("acpi: invalid root system description table\n"));
                        return B_ERROR;
                }

                TRACE(("acpi: rsdt length: %" B_PRIu32 "\n", rsdt->length));
        }

        if (rsdt != NULL) {
                if (acpi_validate_rsdt(rsdt) != B_OK) {
                        TRACE(("acpi: rsdt failed checksum validation\n"));
                        return B_ERROR;
                } else {
                        if (usingXsdt)
                                sAcpiXsdt = rsdt;
                        else
                                sAcpiRsdt = rsdt;
                        TRACE(("acpi: found valid %s at %p\n",
                                usingXsdt ? ACPI_XSDT_SIGNATURE : ACPI_RSDT_SIGNATURE,
                                rsdt));
                }
        } else
                return B_ERROR;

        return B_OK;
}

template<typename PointerType>
acpi_descriptor_header*
acpi_find_table_generic(const char* signature, acpi_descriptor_header* acpiSdt)
{
        if (acpiSdt == NULL)
                return NULL;

        if (sNumEntries == -1) {
                // if using the xsdt, our entries are 64 bits wide.
                sNumEntries = (acpiSdt->length - sizeof(acpi_descriptor_header))
                        / sizeof(PointerType);
        }

        if (sNumEntries <= 0) {
                TRACE(("acpi: root system description table is empty\n"));
                return NULL;
        }

        TRACE(("acpi: searching %" B_PRId32 " entries for table '%.4s'\n", sNumEntries,
                signature));

        PointerType* pointer = (PointerType*)((uint8*)acpiSdt
                + sizeof(acpi_descriptor_header));

        acpi_descriptor_header* header = NULL;
        for (int32 j = 0; j < sNumEntries; j++, pointer++) {
                header = (acpi_descriptor_header*)(addr_t)*pointer;
                if (header != NULL && strncmp(header->signature, signature, 4) == 0) {
                        TRACE(("acpi: Found '%.4s' @ %p\n", signature, pointer));
                        return header;
                }

                TRACE(("acpi: Looking for '%.4s'. Skipping '%.4s'\n",
                        signature, header != NULL ? header->signature : "null"));
                header = NULL;
                continue;
        }

        return NULL;
}


acpi_descriptor_header*
acpi_find_table(const char* signature)
{
        if (sAcpiRsdt != NULL)
                return acpi_find_table_generic<uint32>(signature, sAcpiRsdt);
        else if (sAcpiXsdt != NULL)
                return acpi_find_table_generic<uint64>(signature, sAcpiXsdt);

        return NULL;
}


void __attribute__((weak))
arch_handle_acpi()
{
}


void
acpi_init()
{
        efi_guid acpi = ACPI_20_TABLE_GUID;
        efi_configuration_table *table = kSystemTable->ConfigurationTable;
        size_t entries = kSystemTable->NumberOfTableEntries;

        // Try to find the ACPI RSDP.
        for (uint32 i = 0; i < entries; i++) {
                if (!table[i].VendorGuid.equals(acpi))
                        continue;

                acpi_rsdp *rsdp = (acpi_rsdp *)(table[i].VendorTable);
                if (strncmp((char *)rsdp, ACPI_RSDP_SIGNATURE, 8) == 0)
                        TRACE(("acpi_init: found ACPI RSDP signature at %p\n", rsdp));

                if (rsdp != NULL && acpi_check_rsdt(rsdp) == B_OK) {
                        gKernelArgs.arch_args.acpi_root = rsdp;
                        arch_handle_acpi();
                        break;
                }
        }
}