arbbus.c

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/*
 * PROJECT:     ReactOS Kernel
 * LICENSE:     MIT (https://spdx.org/licenses/MIT)
 * PURPOSE:     PnP manager Root Bus Arbiter
 * COPYRIGHT:   Copyright 2025-2026 Justin Miller <justin.miller@reactos.org>
 */
 
/* INCLUDES *****************************************************************/
 
#include <ntoskrnl.h>
#define NDEBUG
#include <debug.h>
 
/* GLOBALS *******************************************************************/
 
extern ARBITER_INSTANCE IopRootBusNumberArbiter;
 
/* FUNCTIONS *****************************************************************/
 
NTSTATUS
NTAPI
IopArbBusNumberUnpackRequirements(
    _In_ PIO_RESOURCE_DESCRIPTOR IoDescriptor,
    _Out_ PUINT64 OutMinimumAddress,
    _Out_ PUINT64 OutMaximumAddress,
    _Out_ PUINT64 OutLength,
    _Out_ PUINT64 OutAlignment)
{
    PAGED_CODE();
 
    *OutMinimumAddress = IoDescriptor->u.BusNumber.MinBusNumber;
    *OutMaximumAddress = IoDescriptor->u.BusNumber.MaxBusNumber;
    *OutLength = IoDescriptor->u.BusNumber.Length;
    *OutAlignment = 1;
 
    return STATUS_SUCCESS;
}
 
NTSTATUS
NTAPI
IopArbBusNumberPackResource(
    _In_ PIO_RESOURCE_DESCRIPTOR IoDescriptor,
    _In_ UINT64 Start,
    _Out_ PCM_PARTIAL_RESOURCE_DESCRIPTOR CmDescriptor)
{
    PAGED_CODE();
 
    CmDescriptor->Type = CmResourceTypeBusNumber;
    CmDescriptor->ShareDisposition = IoDescriptor->ShareDisposition;
    CmDescriptor->Flags = IoDescriptor->Flags;
    CmDescriptor->u.BusNumber.Start = (ULONG)Start;
    CmDescriptor->u.BusNumber.Length = IoDescriptor->u.BusNumber.Length;
 
    return STATUS_SUCCESS;
}
 
NTSTATUS
NTAPI
IopArbBusNumberUnpackResource(
    _In_ PCM_PARTIAL_RESOURCE_DESCRIPTOR CmDescriptor,
    _Out_ PUINT64 Start,
    _Out_ PUINT64 OutLength)
{
    PAGED_CODE();
 
    *Start  = CmDescriptor->u.BusNumber.Start;
    *OutLength = CmDescriptor->u.BusNumber.Length;
 
    return STATUS_SUCCESS;
}
 
INT32
NTAPI
IopArbBusNumberScoreRequirement(
    _In_ PIO_RESOURCE_DESCRIPTOR IoDescriptor)
{
    PAGED_CODE();
 
    ASSERT(IoDescriptor->u.BusNumber.Length != 0);
    if (IoDescriptor->u.BusNumber.Length == 0)
        return -1;
 
    return (IoDescriptor->u.BusNumber.MaxBusNumber - IoDescriptor->u.BusNumber.MinBusNumber)
           / IoDescriptor->u.BusNumber.Length;
}
 
NTSTATUS
NTAPI
IopArbBusNumberInitialize(VOID)
{
    NTSTATUS Status = STATUS_UNSUCCESSFUL;
 
    PAGED_CODE();
    IopRootBusNumberArbiter.Name = L"RootBusNumber";
    IopRootBusNumberArbiter.UnpackRequirement = IopArbBusNumberUnpackRequirements;
    IopRootBusNumberArbiter.PackResource = IopArbBusNumberPackResource;
    IopRootBusNumberArbiter.UnpackResource = IopArbBusNumberUnpackResource;
    IopRootBusNumberArbiter.ScoreRequirement = IopArbBusNumberScoreRequirement;
 
    Status = ArbiterLibInitializeInstance(&IopRootBusNumberArbiter,
                                          NULL,
                                          CmResourceTypeBusNumber,
                                          IopRootBusNumberArbiter.Name,
                                          L"Root",
                                          NULL);
    if (!NT_SUCCESS(Status))
    {
        DPRINT1("IopArbBusNumberInitialize: Failed with %X", Status);
    }
 
    return Status;
}