/**
 * PROJECT:         ExectOS
 * COPYRIGHT:       See COPYING.md in the top level directory
 * FILE:            xtldr/modules/multiboot2/multiboot2.c
 * DESCRIPTION:     Multiboot2 boot protocol support
 * DEVELOPERS:      Jozef Nagy <schkwve@gmail.com>
 */

#include <multiboot2.h>

/* XTOS module information */
XTBL_MODINFO = L"Multiboot2 boot protocol support";
XTBL_MODDEPS = {L"elf"};

/* EFI XT Loader Protocol */
PXTBL_LOADER_PROTOCOL XtLdrProtocol;

/* XTOS ELF Image Protocol */
PXTBL_EXECUTABLE_IMAGE_PROTOCOL XtElfProtocol;

/* XTOS Boot Protocol */
XTBL_BOOT_PROTOCOL Multiboot2BootProtocol;

/* XTOS Page Map */
PVOID XtPageMap;

/**
 * Starts the operating system according to the provided parameters using XTOS boot protocol.
 *
 * @param Parameters
 *        Input parameters with detailed system configuration like boot device or kernel path.
 *
 * @return This routine returns a status code.
 *
 * @since XT 1.0
 */
XTCDECL
EFI_STATUS
Multiboot2BootSystem(IN PXTBL_BOOT_PARAMETERS Parameters)
{
    EFI_GUID ElfProtocolGuid = XT_ELF_IMAGE_PROTOCOL_GUID;
    EFI_HANDLE DiskHandle, ProtocolHandle;
    PEFI_FILE_HANDLE FsHandle, BootDir;
    PWCHAR SystemPath;
    EFI_STATUS Status;

    /* Print debug message */
    XtLdrProtocol->Debug.Print(L"Multiboot2 boot protocol activated\n");

    /* Open the XT ELF protocol */
    Status = XtLdrProtocol->Protocol.Open(&ProtocolHandle, (PVOID *)&XtElfProtocol, &ElfProtocolGuid);
    if(Status != STATUS_EFI_SUCCESS)
    {
        /* Failed to open loader protocol */
        XtLdrProtocol->Debug.Print(L"ERROR: Unable to load ELF image protocol\n");
        return STATUS_EFI_PROTOCOL_ERROR;
    }

    /* Check device path */
    if(Parameters->DevicePath == NULL)
    {
        /* No device path set */
        XtLdrProtocol->Debug.Print(L"ERROR: No device path provided, unable to boot system\n");
        return STATUS_EFI_INVALID_PARAMETER;
    }

    /* Check if system path is set */
    if(Parameters->SystemPath != NULL)
    {
        /* Make sure system path begins with backslash, the only separator supported by EFI */
        if(Parameters->SystemPath[0] == '/')
        {
            /* Replace directory separator if needed */
            Parameters->SystemPath[0] = '\\';
        }

        /* Validate system path */
        SystemPath = &Parameters->SystemPath[1];
        while(*SystemPath)
        {
            /* Make sure it does not point to any subdirectory and not contains special characters */
            if(((*SystemPath | 32) - 'a' >= 26) && ((*SystemPath - '0') >= 10))
            {
                /* Invalid path specified */
                XtLdrProtocol->Debug.Print(L"ERROR: System path does not point to the valid XTOS installation\n");
                return STATUS_EFI_INVALID_PARAMETER;
            }
            /* Check next character in the path */
            SystemPath++;
        }
    }
    else
    {
        /* Fallback to '/ExectOS' by default */
        XtLdrProtocol->Debug.Print(L"WARNING: No system path set, falling back to defaults\n");
        Parameters->SystemPath = L"\\ExectOS";
    }

    /* Check if kernel file is set */
    if(Parameters->KernelFile == NULL)
    {
        /* No kernel filename set, fallback to default */
        XtLdrProtocol->Debug.Print(L"WARNING: No kernel file specified, falling back to defaults\n");
        Parameters->KernelFile = L"kernel.elf";
    }

    /* Check if provided any kernel boot arguments */
    if(Parameters->Parameters == NULL)
    {
        /* No argument supplied */
        Parameters->Parameters = L"";
    }

    /* Print a debug message */
    XtLdrProtocol->Debug.Print(L"[XTOS] ARC Path: %S\n"
                               L"[XTOS] System Path: %S\n"
                               L"[XTOS] Kernel File: %S\n"
                               L"[XTOS] Boot Arguments: %S\n",
                               Parameters->ArcName, Parameters->SystemPath,
                               Parameters->KernelFile, Parameters->Parameters);

    /* Open EFI volume */
    Status = XtLdrProtocol->Disk.OpenVolume(NULL, &DiskHandle, &FsHandle);
    if(Status != STATUS_EFI_SUCCESS)
    {
        /* Failed to open a volume */
        XtLdrProtocol->Debug.Print(L"ERROR: Unable to open boot volume\n");
        return Status;
    }

    /* System path has to point to the boot directory */
    RtlConcatenateWideString(Parameters->SystemPath, L"\\Boot", 0);

    /* Open XTOS system boot directory */
    Status = FsHandle->Open(FsHandle, &BootDir, Parameters->SystemPath, EFI_FILE_MODE_READ, 0);
    FsHandle->Close(FsHandle);

    /* Check if system path directory opened successfully */
    if(Status == STATUS_EFI_NOT_FOUND)
    {
        /* Directory not found, nothing to load */
        XtLdrProtocol->Debug.Print(L"ERROR: System boot directory not found\n");

        /* Close volume */
        XtLdrProtocol->Disk.CloseVolume(DiskHandle);
        return Status;
    }
    else if(Status != STATUS_EFI_SUCCESS)
    {
        /* Failed to open directory */
        XtLdrProtocol->Debug.Print(L"ERROR: Unable to open system boot directory\n");
        XtLdrProtocol->Disk.CloseVolume(DiskHandle);
        return Status;
    }

    /* Start boot sequence */
    return XtpBootSequence(BootDir, Parameters);
}

/**
 * This routine initiates an XTOS boot sequence.
 *
 * @param BootDir
 *        An EFI handle to the XTOS boot directory.
 *
 * @param Parameters
 *        Input parameters with detailed system configuration like boot device or kernel path.
 *
 * @return This routine returns a status code.
 *
 * @since XT 1.0
 */
XTCDECL
EFI_STATUS
XtpBootSequence(IN PEFI_FILE_HANDLE BootDir,
                IN PXTBL_BOOT_PARAMETERS Parameters)
{
    EFI_GUID LoadedImageGuid = EFI_LOADED_IMAGE_PROTOCOL_GUID;
    PKERNEL_INITIALIZATION_BLOCK KernelParameters;
    PELF_IMAGE_CONTEXT ImageContext = NULL;
    PEFI_LOADED_IMAGE_PROTOCOL ImageProtocol;
    PVOID VirtualAddress, VirtualMemoryArea;
    PXT_ENTRY_POINT KernelEntryPoint;
    LIST_ENTRY MemoryMappings;
    EFI_HANDLE ProtocolHandle;
    EFI_STATUS Status;

    /* Initialize XTOS startup sequence */
    XtLdrProtocol->Debug.Print(L"Initializing XTOS startup sequence\n");

    /* Set base virtual memory area for the kernel mappings */
    VirtualMemoryArea = (PVOID)KSEG0_BASE;
    VirtualAddress = (PVOID)(KSEG0_BASE + KSEG0_KERNEL_BASE);

    /* Load the kernel */
    Status = XtpLoadModule(BootDir, Parameters->KernelFile, VirtualAddress, LoaderSystemCode, &ImageContext);
    if(Status != STATUS_EFI_SUCCESS)
    {
        /* Failed to load the kernel */
        return Status;
    }

    /* Get kernel entry point */
    XtElfProtocol->GetEntryPoint(ImageContext, (PVOID)&KernelEntryPoint);

    /* Close boot directory handle */
    BootDir->Close(BootDir);

    /* Call XTOS kernel */
    XtLdrProtocol->Debug.Print(L"Booting the ELF Multiboot2 kernel\n");
    KernelEntryPoint(KernelParameters);

    /* Return success */
    return STATUS_EFI_SUCCESS;
}

/**
 * Loads XTOS ELF module.
 *
 * @param SystemDir
 *        An EFI handle to the opened system directory containing a module that will be loaded.
 *
 * @param FileName
 *        An on disk filename of the module that will be loaded.
 *
 * @param VirtualAddress
 *        Optional virtual address pointing to the memory area where ELF file will be loaded.
 *
 * @param MemoryType
 *        Supplies the type of memory to be assigned to the memory descriptor.
 *
 * @param ImageContext
 *        Supplies pointer to the memory area where loaded ELF image context will be stored.
 *
 * @return This routine returns a status code.
 *
 * @since XT 1.0
 */
XTCDECL
EFI_STATUS
XtpLoadModule(IN PEFI_FILE_HANDLE SystemDir,
              IN PWCHAR FileName,
              IN PVOID VirtualAddress,
              IN LOADER_MEMORY_TYPE MemoryType,
              OUT PELF_IMAGE_CONTEXT *ImageContext)
{
    PEFI_FILE_HANDLE ModuleHandle;
    USHORT MachineType, SubSystem;
    EFI_STATUS Status;

    /* Print debug message */
    XtLdrProtocol->Debug.Print(L"Loading %S... \n", FileName);

    /* Open module file */
    Status = SystemDir->Open(SystemDir, &ModuleHandle, FileName, EFI_FILE_MODE_READ, 0);
    if(Status != STATUS_EFI_SUCCESS)
    {
        /* Unable to open the file */
        XtLdrProtocol->Debug.Print(L"ERROR: Failed to open '%S'\n", FileName);
        return Status;
    }

    /* Load the ELF image file */
    Status = XtElfProtocol->LoadImage(ModuleHandle, MemoryType, VirtualAddress, (PVOID)ImageContext);
    if(Status != STATUS_EFI_SUCCESS)
    {
        /* Unable to load the file */
        XtLdrProtocol->Debug.Print(L"ERROR: Failed to load '%S'\n", FileName);
        return Status;
    }

    /* Close image file */
    ModuleHandle->Close(ModuleHandle);

    /* Check ELF image machine type compatibility */
    XtElfProtocol->GetMachineType(*ImageContext, &MachineType);
    if(MachineType != 0x03 &&
       MachineType != 0x32 &&
       MachineType != 0x3E)
    {
        /* Machine type mismatch */
        XtLdrProtocol->Debug.Print(L"ERROR: Loaded incompatible ELF image (machine type mismatch)\n");
        return STATUS_EFI_INCOMPATIBLE_VERSION;
    }

    /* Print debug message */
    XtLdrProtocol->Debug.Print(L"Loaded %S at PA: 0x%lx, VA: 0x%lx\n", FileName,
                               (*ImageContext)->PhysicalAddress, (*ImageContext)->VirtualAddress);

    /* Return success */
    return STATUS_EFI_SUCCESS;
}

/**
 * This routine is the entry point of the XT EFI boot loader module.
 *
 * @param ImageHandle
 *        Firmware-allocated handle that identifies the image.
 *
 * @param SystemTable
 *        Provides the EFI system table.
 *
 * @return This routine returns status code.
 *
 * @since XT 1.0
 */
XTCDECL
EFI_STATUS
XtLdrModuleMain(IN EFI_HANDLE ImageHandle,
                IN PEFI_SYSTEM_TABLE SystemTable)
{
    EFI_GUID Guid = XT_XTOS_BOOT_PROTOCOL_GUID;
    EFI_STATUS Status;

    /* Open the XTLDR protocol */
    Status = BlGetXtLdrProtocol(SystemTable, ImageHandle, &XtLdrProtocol);
    if(Status != STATUS_EFI_SUCCESS)
    {
        /* Failed to open loader protocol */
        return STATUS_EFI_PROTOCOL_ERROR;
    }

    /* Set routines available via Multiboot2 boot protocol */
    Multiboot2BootProtocol.BootSystem = Multiboot2BootSystem;

    /* Register XTOS boot protocol */
    XtLdrProtocol->Boot.RegisterProtocol(L"MULTIBOOT2", &Guid);

    /* Install XTOS protocol */
    return XtLdrProtocol->Protocol.Install(&Multiboot2BootProtocol, &Guid);
}