Add New Sample To Git Hub

Adding the new HAL Extension sample to the online repository  in the
"General" Category

6 files changed, 1560 insertions, 0 deletions

diff --git a/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.c b/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.c
new file mode 100644
index 00000000..3aade318
--- /dev/null
+++ b/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.c
@@ -0,0 +1,1253 @@
+/*++
+
+Copyright (c) 2011 Microsoft Corporation
+
+Module Name:
+
+    HalExtSampleDma.c
+
+Abstract:
+
+    This file implements a HAL Extension Module for the fictitious chDMA
+    controller.
+
+Author:
+
+    Cody Hartwig (chartwig) 9-Jun-2011
+
+--*/
+
+//
+// --------------------------------------------------------------------Includes
+//
+
+#include <nthalext.h>
+
+//
+// ---------------------------------------------------------------- Definitions
+//
+
+//
+// Disable warnings of features used by the standard headers
+//
+// Disable warning C4214: nonstandard extension used : bit field types other than int
+// Disable warning C4201: nonstandard extension used : nameless struct/union
+// Disable warning C4115: named type definition in parentheses
+// Disable warning C4127: conditional expression is constant
+// Disable warning C4200: zero-sized array in struct/union
+//
+
+#pragma warning(disable:4214 4201 4115 4127 4200)
+
+//
+// Define register set size.
+//
+
+#define CH_DMA_REGISTER_SIZE            (0x210)
+
+//
+// Define maximums.
+//
+
+#define CH_DMA_MAX_REQUEST_LINES        (32)
+#define CH_DMA_MAX_CHANNELS             (32)
+
+#define CONFIGURE_ADD_REQ_CONFIG        (0x80000000)
+
+//
+// Define register offsets.
+//
+
+#define CH_DMA_CONTROL                  (0x00)
+#define CH_DMA_STATUS                   (0x04)
+#define CH_DMA_INTERRUPT_MASK           (0x08)
+
+#define CH_DMA_CHAN_CONTROL             (0x00)
+#define CH_DMA_CHAN_MEM_PTR             (0x04)
+#define CH_DMA_CHAN_DEV_PTR             (0x08)
+#define CH_DMA_CHAN_STATUS              (0x1c)
+
+//
+// Define device-side bus widths.
+//
+
+#define CH_DMA_WIDTH_8_BIT              (0)
+#define CH_DMA_WIDTH_16_BIT             (1)
+#define CH_DMA_WIDTH_32_BIT             (2)
+
+//
+// Define transfer burst sizes.
+//
+
+#define CH_DMA_BURST_1_WORD             (0)
+#define CH_DMA_BURST_2_WORD             (1)
+#define CH_DMA_BURST_4_WORD             (2)
+#define CH_DMA_BURST_8_WORD             (3)
+
+//
+// Define transfer directions.
+//
+
+#define CH_DMA_DEVICE_WRITE             (0)
+#define CH_DMA_DEVICE_READ              (1)
+
+//
+// ------------------------------------------------------ Data Type Definitions
+//
+
+#pragma pack(push, 1)
+
+//
+// Register Definitions.
+//
+
+typedef struct _CH_DMA_CONTROL_REGISTER {
+    union {
+        struct {
+            ULONG ControllerEnable:1;
+            ULONG Reserved:31;
+        };
+        ULONG AsUlong;
+    };
+} CH_DMA_CONTROL_REGISTER, *PCH_DMA_CONTROL_REGISTER;
+
+typedef struct _CH_DMA_CHAN_CONTROL_REGISTER {
+    union {
+        struct {
+            ULONG ChannelEnable:1;
+            ULONG InterruptEnable:1;
+            ULONG DeviceWidth:2;
+            ULONG BurstSize:2;
+            ULONG FlowControl:1;
+            ULONG Loop:1;
+            ULONG RequestLine:5;
+            ULONG ReadFromDevice:1;
+            ULONG Reserved:2;
+            ULONG Length:16;
+        };
+        ULONG AsUlong;
+    };
+} CH_DMA_CHAN_CONTROL_REGISTER, *PCH_DMA_CHAN_CONTROL_REGISTER;
+
+typedef struct _CH_DMA_CHAN_STATUS_REGISTER {
+    union {
+        struct {
+            ULONG Busy:1;
+            ULONG Reserved:15;
+            ULONG BytesTransferred:16;
+        };
+        ULONG AsUlong;
+    };
+} CH_DMA_CHAN_STATUS_REGISTER, *PCH_DMA_CHAN_STATUS_REGISTER;
+
+//
+// CSRT resource descriptor types for chDMA.
+//
+
+typedef struct _CH_DMA_ADD_REQ_LINE_CONFIG {
+    ULONG RequestLine;
+    CH_DMA_CHAN_CONTROL_REGISTER Ctrl;
+} CH_DMA_ADD_REQ_LINE_CONFIG, *PCH_DMA_ADD_REQ_LINE_CONFIG;
+
+typedef struct _RD_DMA_CONTROLLER {
+    CSRT_RESOURCE_DESCRIPTOR_HEADER Header;
+    ULONGLONG BasePhysicalAddress;
+    ULONG ChannelCount;
+    ULONG MinimumRequestLine;
+    ULONG MaximumRequestLine;
+    ULONG InterruptGsi;
+    BOOLEAN CacheCoherent;
+    ULONG ReqLineConfigCount;
+    CH_DMA_ADD_REQ_LINE_CONFIG ReqLineConfigs[ANYSIZE_ARRAY];
+} RD_DMA_CONTROLLER, *PRD_DMA_CONTROLLER;
+
+//
+// Resource description matching chDMA controller described in chdmaReadme.txt:
+//
+// CH_DMA_CHAN_CONTROL_REGISTER UartControl;
+// UartControl.AsUlong = 0;
+// UartControl.DeviceWidth = CH_DMA_WIDTH_8_BIT;
+// UartControl.BurstSize = CH_DMA_BURST_1_WORD;
+// UartControl.FlowControl = 1;
+//
+// CH_DMA_ADD_REQ_LINE_CONFIG UartConfig = {
+//      0x15,
+//      UartControl
+// };
+//
+// RD_DMA_CONTROLLER DmaDesc = {
+//      Header,
+//      0x70001000,
+//      32,
+//      0,
+//      31,
+//      0x27,
+//      FALSE,
+//      1,
+//      { UartConfig }
+// };
+//
+
+typedef struct _RD_DMA_CHANNEL {
+    CSRT_RESOURCE_DESCRIPTOR_HEADER Header;
+    ULONG ChannelNumber;
+} RD_DMA_CHANNEL, *PRD_DMA_CHANNEL;
+
+//
+// Resource description matching chDMA channel described in chdmaReadme.txt:
+//
+// RD_DMA_CHANNEL DmaDesc = {
+//      Header,
+//      0
+// };
+//
+
+#pragma pack(pop)
+
+//
+// Extension Request line to configuration mapping.
+//
+
+typedef struct _CH_REQ_LINE_CONFIG {
+    BOOLEAN Valid;
+    CH_DMA_CHAN_CONTROL_REGISTER Ctrl;
+} CH_REQ_LINE_CONFIG, *PCH_REQ_LINE_CONFIG;
+
+typedef struct _CH_REQ_LINE_CONFIG_TABLE {
+    CH_REQ_LINE_CONFIG Entries[CH_DMA_MAX_REQUEST_LINES];
+} CH_DMA_REQ_LINE_CONFIG_TABLE, *PCH_DMA_REQ_LINE_CONFIG_TABLE;
+
+//
+// Define extension internal data for the controller and channel.
+//
+
+typedef struct _CH_DMA_CHANNEL {
+    BOOLEAN Active;
+    BOOLEAN AutoInit;
+} CH_DMA_CHANNEL, *PCH_DMA_CHANNEL;
+
+typedef struct _CH_DMA_CONTROLLER {
+
+    //
+    // Virtual and physical base addresses of the controller.
+    //
+
+    PULONG ControllerBaseVa;
+    PHYSICAL_ADDRESS ControllerBasePa;
+
+    ULONG ChannelCount;
+    ULONG MinimumRequestLine;
+    ULONG MaximumRequestLine;
+
+    //
+    // Individual channel extension status.
+    //
+
+    CH_DMA_CHANNEL Channels[CH_DMA_MAX_CHANNELS];
+
+    //
+    // Request line to configuration mapping.
+    //
+
+    CH_DMA_REQ_LINE_CONFIG_TABLE ReqConfig;
+} CH_DMA_CONTROLLER, *PCH_DMA_CONTROLLER;
+
+//
+// ----------------------------------------------------------------- Prototypes
+//
+
+VOID
+ChInitializeController (
+    __in PVOID ControllerContext
+    );
+
+BOOLEAN
+ChValidateRequestLineBinding (
+    __in PVOID ControllerContext,
+    __in PDMA_REQUEST_LINE_BINDING_DESCRIPTION BindingDescription
+    );
+
+ULONG
+ChQueryMaxFragments (
+    __in PVOID ControllerContext,
+    __in ULONG ChannelNumber,
+    __in ULONG MaxFragmentsRequested
+    );
+
+VOID
+ChProgramChannel (
+    __in PVOID ControllerContext,
+    __in ULONG ChannelNumber,
+    __in ULONG RequestLine,
+    __in PDMA_SCATTER_GATHER_LIST MemoryAddresses,
+    __in PHYSICAL_ADDRESS DeviceAddress,
+    __in BOOLEAN WriteToDevice,
+    __in BOOLEAN LoopTransfer
+    );
+
+BOOLEAN
+ChCancelTransfer (
+    __in PVOID ControllerContext,
+    __in ULONG ChannelNumber
+    );
+
+NTSTATUS
+ChConfigureChannel (
+    __in PVOID ControllerContext,
+    __in ULONG ChannelNumber,
+    __in ULONG FunctionNumber,
+    __in PVOID Context
+    );
+
+VOID
+ChFlushChannel (
+    __in PVOID ControllerContext,
+    __in ULONG ChannelNumber
+    );
+
+_Success_(return != FALSE)
+BOOLEAN
+ChHandleInterrupt (
+    __in PVOID ControllerContext,
+    __out PULONG ChannelNumber,
+    __out PDMA_INTERRUPT_TYPE InterruptType
+    );
+
+ULONG
+ChReadDmaCounter (
+    __in PVOID ControllerContext,
+    __in ULONG ChannelNumber
+    );
+
+//
+// -------------------------------------------------------------------- Globals
+//
+
+DMA_FUNCTION_TABLE ChFunctionTable =
+{
+    ChInitializeController,
+    ChValidateRequestLineBinding,
+    ChQueryMaxFragments,
+    ChProgramChannel,
+    ChConfigureChannel,
+    ChFlushChannel,
+    ChHandleInterrupt,
+    ChReadDmaCounter,
+    NULL, /* ReportCommonBuffer */
+    ChCancelTransfer
+};
+
+//
+// ------------------------------------------------------------------- Routines
+//
+
+VOID
+WriteRegister (
+    __in PCH_DMA_CONTROLLER Controller,
+    __in ULONG RegisterOffset,
+    __in ULONG Value
+    )
+
+{
+
+    PULONG Address;
+
+    Address = Controller->ControllerBaseVa;
+
+    //
+    // Add register offset.  Register offset is in bytes.  Pointer addition is
+    // in ULONGs.
+    //
+
+    Address += (RegisterOffset / 4);
+
+    WRITE_REGISTER_ULONG(Address, Value);
+}
+
+ULONG
+ReadRegister (
+    __in PCH_DMA_CONTROLLER Controller,
+    __in ULONG RegisterOffset
+    )
+
+{
+
+    PULONG Address;
+
+    Address = Controller->ControllerBaseVa;
+
+    //
+    // Add register offset.  Register offset is in bytes.  Pointer addition is
+    // in ULONGs.
+    //
+
+    Address += (RegisterOffset / 4);
+
+    return READ_REGISTER_ULONG(Address);
+}
+
+VOID
+WriteChannelRegister (
+    __in PCH_DMA_CONTROLLER Controller,
+    __in ULONG ChannelNumber,
+    __in ULONG RegisterOffset,
+    __in ULONG Value
+    )
+
+{
+    PULONG Address;
+
+    Address = Controller->ControllerBaseVa;
+
+    //
+    // Add channel base offset.
+    // Register offset is in bytes.  Pointer addition is in ULONGs.
+    //
+
+    Address += (0x10 / 4);
+
+    //
+    // Add channel number offset.
+    //
+
+    Address += ((0x10 * ChannelNumber) / 4);
+
+    //
+    // Add channel register offset.
+    //
+
+    Address += (RegisterOffset / 4);
+
+    WRITE_REGISTER_ULONG(Address, Value);
+}
+
+ULONG
+ReadChannelRegister (
+    __in PCH_DMA_CONTROLLER Controller,
+    __in ULONG ChannelNumber,
+    __in ULONG RegisterOffset
+    )
+
+{
+
+    PULONG Address;
+
+    Address = Controller->ControllerBaseVa;
+
+    //
+    // Add channel base offset.
+    // Register offset is in bytes.  Pointer addition is in ULONGs.
+    //
+
+    Address += (0x10 / 4);
+
+    //
+    // Add channel number offset.
+    //
+
+    Address += ((0x10 * ChannelNumber) / 4);
+
+    //
+    // Add channel register offset.
+    //
+
+    Address += (RegisterOffset / 4);
+
+    return READ_REGISTER_ULONG(Address);
+}
+
+VOID
+ChInitializeController (
+    __in PVOID ControllerContext
+    )
+
+/*++
+
+Routine Description:
+
+    This routine provides an opportunity for DMA controllers to initialize.
+
+Arguments:
+
+    ControllerContext - Supplies a pointer to the controller's internel data.
+
+Return Value:
+
+    None.
+
+--*/
+
+{
+
+    CH_DMA_CONTROL_REGISTER CtrlRegister;
+    PCH_DMA_CONTROLLER Controller;
+    ULONG Index;
+    ULONG InterruptMask;
+
+    Controller = (PCH_DMA_CONTROLLER)ControllerContext;
+
+    //
+    // Map the controller base iff this is the first call to init (and it is
+    // therefore not already mapped.)
+    //
+
+    if (Controller->ControllerBaseVa == NULL) {
+        Controller->ControllerBaseVa =
+            (PULONG) HalMapIoSpace(Controller->ControllerBasePa,
+                                   PAGE_SIZE,
+                                   MmNonCached);
+
+        NT_ASSERT(Controller->ControllerBaseVa != NULL);
+    }
+
+    if (Controller->ControllerBaseVa == NULL) {
+        return;
+    }
+
+    //
+    // Initialize each channel.
+    //
+
+    for (Index = 0; Index < Controller->ChannelCount; Index += 1) {
+        WriteChannelRegister(Controller, Index, CH_DMA_CHAN_CONTROL, 0);
+        Controller->Channels[Index].Active = FALSE;
+        Controller->Channels[Index].AutoInit = FALSE;
+    }
+
+    //
+    // Enable the DMA controller.
+    //
+
+    CtrlRegister.AsUlong = 0;
+    CtrlRegister.ControllerEnable = 1;
+    WriteRegister(Controller, CH_DMA_CONTROL, CtrlRegister.AsUlong);
+
+    //
+    // Enable all interrupts.
+    //
+
+    InterruptMask = (1UL << Controller->ChannelCount) - 1;
+    WriteRegister(Controller, CH_DMA_INTERRUPT_MASK, InterruptMask);
+
+    return;
+}
+
+BOOLEAN
+ChValidateRequestLineBinding (
+    __in PVOID ControllerContext,
+    __in PDMA_REQUEST_LINE_BINDING_DESCRIPTION BindingDescription
+    )
+
+/*++
+
+Routine Description:
+
+    This routine queries a DMA controller extension to test the validity of a
+    request line binding.
+
+Arguments:
+
+    ControllerContext - Supplies a pointer to the controller's internal data.
+
+    DeviceDescription - Supplies a pointer to the request information.
+
+Return Value:
+
+    TRUE if the request line binding is valid and supported by the controller.
+
+    FALSE if the binding is invalid.
+
+Environment:
+
+    PASSIVE_LEVEL.
+
+--*/
+
+{
+
+    PCH_DMA_CONTROLLER Controller;
+
+    Controller = (PCH_DMA_CONTROLLER)ControllerContext;
+    if (BindingDescription->ChannelNumber > Controller->ChannelCount) {
+        return FALSE;
+    }
+
+    if ((BindingDescription->RequestLine > Controller->MaximumRequestLine) ||
+        (BindingDescription->RequestLine < Controller->MinimumRequestLine)) {
+
+        return FALSE;
+    }
+
+    return TRUE;
+}
+
+ULONG
+ChQueryMaxFragments (
+    __in PVOID ControllerContext,
+    __in ULONG ChannelNumber,
+    __in ULONG MaxFragmentsRequested
+    )
+
+/*++
+
+Routine Description:
+
+    This routine queries the DMA extension to determine the number of
+    scatter gather fragments that the next transfer can support.
+
+Arguments:
+
+    ControllerContext - Supplies a pointer to the controller's internal data.
+
+    ChannelNumber - Supplies the number of the channel to program.
+
+    MaxFragmentsRequested - Supplies a hint to the maximum fragments useful to
+        this transfer.
+
+Return Value:
+
+    Number of fragments the next transfer on this channel can support.
+
+--*/
+
+{
+
+    UNREFERENCED_PARAMETER(ControllerContext);
+    UNREFERENCED_PARAMETER(ChannelNumber);
+    UNREFERENCED_PARAMETER(MaxFragmentsRequested);
+
+    return 1;
+}
+
+VOID
+ChProgramChannel (
+    __in PVOID ControllerContext,
+    __in ULONG ChannelNumber,
+    __in ULONG RequestLine,
+    __in PDMA_SCATTER_GATHER_LIST MemoryAddresses,
+    __in PHYSICAL_ADDRESS DeviceAddress,
+    __in BOOLEAN WriteToDevice,
+    __in BOOLEAN LoopTransfer
+    )
+
+/*++
+
+Routine Description:
+
+    This routine programs a DMA controller channel for a specific transfer.
+
+Arguments:
+
+    ControllerContext - Supplies a pointer to the controller's internal data.
+
+    ChannelNumber - Supplies the number of the channel to program.
+
+    RequestLine - Supplies the request line number to program.  This request
+        line number is system-unique (as provided to the HAL during
+        registration) and must be translated by the extension.
+
+    MemoryAddress - Supplies the address to be programmed into the memory
+        side of the channel configuration.
+
+    DeviceAddress - Supplies the address to be programmed into the device
+        side of the channel configuration.
+
+    WriteToDevice - Supplies the direction of the transfer.
+
+    LoopTransfer - Supplies whether AutoInitialize has been set in the
+        adapter making this request.
+
+Return Value:
+
+    None.
+
+--*/
+
+{
+
+    CH_DMA_CHAN_CONTROL_REGISTER Ctrl;
+    PCH_DMA_CONTROLLER Controller;
+    ULONG DevPtr;
+    ULONG MemPtr;
+
+    Controller = (PCH_DMA_CONTROLLER)ControllerContext;
+    Controller->Channels[ChannelNumber].Active = TRUE;
+
+    //
+    // If this request line exists in the request line config table, use
+    // those values.  Otherwise, use the reset values.
+    //
+
+    Ctrl.AsUlong = 0;
+    if (Controller->ReqConfig.Entries[RequestLine].Valid != 0) {
+        Ctrl.AsUlong = Controller->ReqConfig.Entries[RequestLine].Ctrl.AsUlong;
+    }
+
+    Ctrl.ChannelEnable = 1;
+    Ctrl.InterruptEnable = 1;
+    Ctrl.Loop = (LoopTransfer == FALSE) ? 0 : 1;
+    Ctrl.ReadFromDevice = (WriteToDevice == FALSE) ? 1 : 0;
+
+    //
+    // Request lines numbers reported by BIOS may be offset to make them
+    // globally unique.  Request lines on the controller are based at 0.
+    //
+
+    Ctrl.RequestLine = RequestLine - Controller->MinimumRequestLine;
+    Ctrl.Length = MemoryAddresses->Elements[0].Length;
+
+    DevPtr = DeviceAddress.LowPart;
+    MemPtr = MemoryAddresses->Elements[0].Address.LowPart;
+
+    WriteChannelRegister(Controller,
+                         ChannelNumber,
+                         CH_DMA_CHAN_MEM_PTR,
+                         MemPtr);
+
+    WriteChannelRegister(Controller,
+                         ChannelNumber,
+                         CH_DMA_CHAN_DEV_PTR,
+                         DevPtr);
+
+    //
+    // Channel control is written last as it will enable the channel.
+    //
+
+    WriteChannelRegister(Controller,
+                         ChannelNumber,
+                         CH_DMA_CHAN_CONTROL,
+                         Ctrl.AsUlong);
+}
+
+BOOLEAN
+ChCancelTransfer (
+    __in PVOID ControllerContext,
+    __in ULONG ChannelNumber
+    )
+
+/*++
+
+Routine Description:
+
+    This routine must disable the selected channel.  The channel must not be
+    capable of interrupting for this transfer after being cleared in this way.
+
+Arguments:
+
+    ControllerContext - Supplies a pointer to the controller's internal data.
+
+    ChannelNumber - Supplies the channel number.
+
+Return Value:
+
+    FALSE if the channel is already idle or if the channel is already asserting
+    an interrupt.  TRUE is the channel is active and no interrupt is asserted.
+
+--*/
+
+{
+
+    PCH_DMA_CONTROLLER Controller;
+    ULONG StatusRegister;
+
+    Controller = (PCH_DMA_CONTROLLER)ControllerContext;
+
+    //
+    // If the channel is not active (because the interrupt already fired or
+    // because the channel was never programmed, return immediately.
+    //
+
+    if (Controller->Channels[ChannelNumber].Active == FALSE) {
+        return FALSE;
+    }
+
+    //
+    // Disable the channel.
+    //
+
+    WriteChannelRegister(Controller, ChannelNumber, CH_DMA_CHAN_CONTROL, 0);
+
+    //
+    // If an interrupt is already pending on the channel, do nothing.  The
+    // normal interrupt path will complete it.  If an interrupt is not pending
+    // then this was successfully cancelled.  In that case, mark the channel
+    // inactive and return TRUE.
+    //
+
+    StatusRegister = ReadRegister(Controller, CH_DMA_STATUS);
+    if ((StatusRegister & (1UL << ChannelNumber)) != 0) {
+        return FALSE;
+
+    } else {
+        Controller->Channels[ChannelNumber].Active = FALSE;
+        return TRUE;
+    }
+}
+
+NTSTATUS
+AddReqLineConfig (
+    __in PCH_DMA_CONTROLLER Controller,
+    __in PCH_DMA_ADD_REQ_LINE_CONFIG Config
+    )
+
+/*++
+
+Routine Description:
+
+    This routine updates the request line configuration table in the
+    extension's internal data for this controller.
+
+Arguments:
+
+    Controller - Supplies a pointer to the internal data for the controller.
+
+    Config - Supplies a pointer to the configuration to modify.
+
+Return Value:
+
+    STATUS_INVALID_PARAMETER if the request line is invalid.
+    Else, STATUS_SUCCESS.
+
+--*/
+
+{
+
+    ULONG RequestLine;
+
+    RequestLine = Config->RequestLine;
+    if ((RequestLine < Controller->MinimumRequestLine) ||
+        (RequestLine > Controller->MaximumRequestLine)) {
+
+        return STATUS_INVALID_PARAMETER;
+    }
+
+    Controller->ReqConfig.Entries[RequestLine].Ctrl.AsUlong =
+        Config->Ctrl.AsUlong;
+
+    return STATUS_SUCCESS;
+}
+
+NTSTATUS
+ChConfigureChannel (
+    __in PVOID ControllerContext,
+    __in ULONG ChannelNumber,
+    __in ULONG FunctionNumber,
+    __in PVOID Context
+    )
+
+/*++
+
+Routine Description:
+
+    This routine configures the channel for a DMA extension specific operation.
+
+Arguments:
+
+    ControllerContext - Supplies a pointer to the controller's internal data.
+
+    ChannelNumber - Supplies the channel to configure.
+
+    FunctionNumber - Supplies the ID of the operation to perform.
+
+    Context - Supplies parameters for this operation.
+
+Return Value:
+
+    NTSTATUS code.
+
+--*/
+
+{
+
+    PCH_DMA_CONTROLLER Controller;
+    NTSTATUS Status;
+
+    UNREFERENCED_PARAMETER(ChannelNumber);
+
+    Controller = (PCH_DMA_CONTROLLER)ControllerContext;
+    switch (FunctionNumber) {
+    case CONFIGURE_ADD_REQ_CONFIG:
+        Status = AddReqLineConfig(Controller,
+                                  (PCH_DMA_ADD_REQ_LINE_CONFIG)Context);
+
+        break;
+    default:
+        Status = STATUS_NOT_IMPLEMENTED;
+    }
+
+    return Status;
+}
+
+VOID
+ChFlushChannel (
+    __in PVOID ControllerContext,
+    __in ULONG ChannelNumber
+    )
+
+/*++
+
+Routine Description:
+
+    This routine flushes a previous transfer from a channel and returns the
+    channel to a state ready for the next ProgramChannel call.
+
+Arguments:
+
+    ControllerContext - Supplies a pointer to the controller's internal data.
+
+    ChannelNumber - Supplies the channel to flush.
+
+Return Value:
+
+    None.
+
+--*/
+
+{
+
+    PCH_DMA_CONTROLLER Controller;
+
+    Controller = (PCH_DMA_CONTROLLER)ControllerContext;
+    WriteChannelRegister(Controller, ChannelNumber, CH_DMA_CHAN_CONTROL, 0);
+}
+
+_Success_(return != FALSE)
+BOOLEAN
+ChHandleInterrupt (
+    __in PVOID ControllerContext,
+    __out PULONG ChannelNumber,
+    __out PDMA_INTERRUPT_TYPE InterruptType
+    )
+
+/*++
+
+Routine Description:
+
+    This routine probes a controller for interrupts, clears any interrupts
+    found, fills in channel and interrupt type information.  This routine
+    will be called repeatedly until FALSE is returned.
+
+Arguments:
+
+    ControllerContext - Supplies a pointer to the controller's internal data.
+
+    ChannelNumber - Supplies a placeholder for the extension to fill in which
+        channel is interrupting.
+
+    InterruptType - Supplies a placeholder for the extension to fill in the
+        interrupt type.
+
+Return Value:
+
+    TRUE if an interrupt was found on this controller.
+
+    FALSE otherwise.
+
+--*/
+
+{
+
+    PCH_DMA_CONTROLLER Controller;
+    ULONG Index;
+    ULONG StatusRegister;
+
+    Controller = (PCH_DMA_CONTROLLER)ControllerContext;
+    StatusRegister = ReadRegister(Controller, CH_DMA_STATUS);
+    for (Index = 0; Index < Controller->ChannelCount; Index += 1) {
+        if ((StatusRegister & (1UL << Index)) != 0) {
+            *ChannelNumber = Index;
+            *InterruptType = InterruptTypeCompletion;
+            WriteRegister(Controller, CH_DMA_STATUS, (1UL << Index));
+
+            //
+            // If the channel is not marked as active, then this interrupt
+            // is spurious.  Probably this is the result of a transfer being
+            // cancelled.
+            //
+
+            if (Controller->Channels[Index].Active == FALSE) {
+                continue;
+            }
+
+            //
+            // If the channel is not in autoinitialize mode, is it inactive now.
+            // If the channel is in autoinitialize, then it will remain active
+            // until it receives a cancel.
+            //
+
+            if (Controller->Channels[Index].AutoInit == FALSE) {
+                Controller->Channels[Index].Active = FALSE;
+            }
+
+            return TRUE;
+        }
+    }
+
+    return FALSE;
+}
+
+ULONG ChReadDmaCounter (
+    __in PVOID ControllerContext,
+    __in ULONG ChannelNumber
+    )
+
+/*++
+
+Routine Description:
+
+    This routine determines how many bytes remain to be transferred on the
+    given channel.  If the current transfer is set to loop, this routine
+    will return the number of bytes remaining in the current iteration.
+
+Arguments:
+
+    ControllerContext - Supplies a pointer to the controller's internal data.
+
+    ChannelNumber - Supplies the channel number.
+
+Return Value:
+
+    Returns the number of bytes remaining to be transferred on the given
+    channel.
+
+--*/
+
+{
+
+    PCH_DMA_CONTROLLER Controller;
+    CH_DMA_CHAN_CONTROL_REGISTER Ctrl;
+    CH_DMA_CHAN_STATUS_REGISTER StatusReg;
+
+    Controller = (PCH_DMA_CONTROLLER)ControllerContext;
+    Ctrl.AsUlong = ReadChannelRegister(Controller,
+                                       ChannelNumber,
+                                       CH_DMA_CHAN_CONTROL);
+
+    StatusReg.AsUlong = ReadChannelRegister(Controller,
+                                            ChannelNumber,
+                                            CH_DMA_CHAN_STATUS);
+
+    return (Ctrl.Length - StatusReg.BytesTransferred);
+}
+
+NTSTATUS
+RegisterDmaController (
+    __in ULONG Handle,
+    __in PCSRT_RESOURCE_GROUP_HEADER ResourceGroup,
+    __in PCSRT_RESOURCE_DESCRIPTOR_HEADER ResourceDescriptor,
+    __out PULONG ControllerId
+    )
+
+/*++
+
+Routine Description:
+
+    This routine takes a DMA resource descriptor with subtype controller.
+    The controller is then registered with the HAL.
+
+Arguments:
+
+    Handle - Supplies handle passed to extension.
+
+    ResourceGroup - Supplies resource group containing this descriptor.
+
+    ResourceDescrpitor - Supplies the resource descriptor.
+
+    ControllerId - Supplies a placeholder for the controller ID returned from
+        the HAL after registration.
+
+Return Value:
+
+    NTSTATUS Value.
+
+--*/
+
+{
+
+    PCH_REQ_LINE_CONFIG ConfigEntry;
+    PCH_REQ_LINE_CONFIG ConfigTableDst;
+    PCH_DMA_ADD_REQ_LINE_CONFIG ConfigTableSrc;
+    CH_DMA_CONTROLLER Controller;
+    PRD_DMA_CONTROLLER DmaDesc;
+    DMA_INITIALIZATION_BLOCK DmaInitBlock;
+    ULONG Index;
+    ULONG RequestLine;
+    NTSTATUS Status;
+
+    RtlZeroMemory(&Controller, sizeof(CH_DMA_CONTROLLER));
+
+    DmaDesc = (PRD_DMA_CONTROLLER)ResourceDescriptor;
+    Controller.ControllerBasePa.QuadPart = DmaDesc->BasePhysicalAddress;
+    Controller.ChannelCount = DmaDesc->ChannelCount;
+    Controller.MinimumRequestLine = DmaDesc->MinimumRequestLine;
+    Controller.MaximumRequestLine = DmaDesc->MaximumRequestLine;
+
+    //
+    // Build request line configuration mapping table.
+    //
+
+    ConfigTableDst = &Controller.ReqConfig.Entries[0];
+    ConfigTableSrc = &DmaDesc->ReqLineConfigs[0];
+
+    //
+    // Verify the supplied configuration description will fit within
+    // the build maximum.
+    //
+
+    if (DmaDesc->ReqLineConfigCount >= CH_DMA_MAX_REQUEST_LINES) {
+        Status = STATUS_INVALID_PARAMETER_1;
+        goto Exit;
+    }
+
+    for (Index = 0; Index < DmaDesc->ReqLineConfigCount; Index += 1) {
+
+        RequestLine = ConfigTableSrc[Index].RequestLine;
+
+        //
+        // Keep PreFast happy that we're assigning within memory bounds
+        //
+
+        if (RequestLine >= CH_DMA_MAX_REQUEST_LINES) {
+            Status = STATUS_INVALID_PARAMETER_2;
+            goto Exit;
+        }
+
+        ConfigEntry = &ConfigTableDst[RequestLine];
+        ConfigEntry->Ctrl.AsUlong = ConfigTableSrc[Index].Ctrl.AsUlong;
+        ConfigEntry->Valid = TRUE;
+    }
+
+    INITIALIZE_DMA_HEADER(&DmaInitBlock);
+    DmaInitBlock.ChannelCount = Controller.ChannelCount;
+    DmaInitBlock.MinimumTransferUnit = 1;
+    DmaInitBlock.MinimumRequestLine = Controller.MinimumRequestLine;
+    DmaInitBlock.MaximumRequestLine = Controller.MaximumRequestLine;
+    DmaInitBlock.CacheCoherent = DmaDesc->CacheCoherent;
+    DmaInitBlock.GeneratesInterrupt = TRUE;
+    DmaInitBlock.InternalData = (PVOID)&Controller;
+    DmaInitBlock.InternalDataSize = sizeof(CH_DMA_CONTROLLER);
+    DmaInitBlock.DmaAddressWidth = 32;
+    DmaInitBlock.Gsi = DmaDesc->InterruptGsi;
+    DmaInitBlock.InterruptPolarity = InterruptActiveHigh;
+    DmaInitBlock.InterruptMode = LevelSensitive;
+    DmaInitBlock.Operations = &ChFunctionTable;
+
+    //
+    // Register physical address space with the HAL.
+    //
+
+    HalRegisterPermanentAddressUsage(Controller.ControllerBasePa,
+                                     CH_DMA_REGISTER_SIZE);
+
+    //
+    // Register controller.
+    //
+
+    Status = RegisterResourceDescriptor(Handle,
+                                        ResourceGroup,
+                                        ResourceDescriptor,
+                                        &DmaInitBlock);
+
+    *ControllerId = DmaInitBlock.ControllerId;
+
+Exit:
+    return Status;
+
+}
+
+NTSTATUS
+RegisterDmaChannel (
+    __in ULONG Handle,
+    __in PCSRT_RESOURCE_GROUP_HEADER ResourceGroup,
+    __in PCSRT_RESOURCE_DESCRIPTOR_HEADER ResourceDescriptor,
+    __in ULONG ControllerId
+    )
+
+/*++
+
+Routine Description:
+
+    This routine takes a DMA resource descriptor with subtype channel.
+    The channel is then registered with the HAL.
+
+Arguments:
+
+    Handle - Supplies handle passed to extension.
+
+    ResourceGroup - Supplies resource group containing this descriptor.
+
+    ResourceDescrpitor - Supplies the resource descriptor.
+
+    ControllerId - Supplies the controller ID this channel is registered with.
+
+Return Value:
+
+    NTSTATUS Value.
+
+--*/
+
+{
+
+    DMA_CHANNEL_INITIALIZATION_BLOCK DmaChannelInitBlock;
+    PRD_DMA_CHANNEL DmaDesc;
+
+    NT_ASSERT(ControllerId != 0);
+
+    DmaDesc = (PRD_DMA_CHANNEL)ResourceDescriptor;
+    INITIALIZE_DMA_CHANNEL_HEADER(&DmaChannelInitBlock);
+    DmaChannelInitBlock.ControllerId = ControllerId;
+    DmaChannelInitBlock.GeneratesInterrupt = FALSE;
+    DmaChannelInitBlock.ChannelNumber = DmaDesc->ChannelNumber;
+    DmaChannelInitBlock.CommonBufferLength = 0;
+
+    return RegisterResourceDescriptor(Handle,
+                                      ResourceGroup,
+                                      ResourceDescriptor,
+                                      &DmaChannelInitBlock);
+}
+
+NTSTATUS
+AddResourceGroup (
+    __in ULONG Handle,
+    __in PCSRT_RESOURCE_GROUP_HEADER ResourceGroup
+    )
+
+{
+
+    ULONG ControllerId;
+    PCSRT_RESOURCE_DESCRIPTOR_HEADER ResourceDescriptor;
+
+    ResourceDescriptor = NULL;
+    ControllerId = 0;
+    for (;;) {
+        ResourceDescriptor =
+            GetNextResourceDescriptor(Handle,
+                                      ResourceGroup,
+                                      ResourceDescriptor,
+                                      CSRT_RD_TYPE_DMA,
+                                      CSRT_RD_SUBTYPE_ANY,
+                                      CSRT_RD_UID_ANY);
+
+        if (ResourceDescriptor == NULL) {
+            break;
+        }
+
+        if (ResourceDescriptor->Subtype == CSRT_RD_SUBTYPE_DMA_CONTROLLER) {
+            RegisterDmaController(Handle,
+                                  ResourceGroup,
+                                  ResourceDescriptor,
+                                  &ControllerId);
+
+        } else if (ResourceDescriptor->Subtype == CSRT_RD_SUBTYPE_DMA_CHANNEL) {
+            RegisterDmaChannel(Handle,
+                               ResourceGroup,
+                               ResourceDescriptor,
+                               ControllerId);
+        } else {
+
+            NT_ASSERT(FALSE);
+        }
+    }
+
+    return STATUS_SUCCESS;
+}
diff --git a/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.def b/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.def
new file mode 100644
index 00000000..22ecba00
--- /dev/null
+++ b/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.def
@@ -0,0 +1,2 @@
+LIBRARY HalExtSampleDma
+
diff --git a/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.rc b/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.rc
new file mode 100644
index 00000000..534afafb
--- /dev/null
+++ b/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.rc
@@ -0,0 +1,10 @@
+#include "verrsrc.h"
+#include <ntverp.h>
+
+#define VER_FILETYPE                VFT_DLL
+#define VER_FILESUBTYPE             VFT_UNKNOWN
+#define VER_FILEDESCRIPTION_STR     "HAL Extension Sample - DMA"
+#define VER_INTERNALNAME_STR        "HalExtSampleDma.DLL"
+#define VER_ORIGINALFILENAME_STR    "HalExtSampleDma.DLL"
+
+#include <common.ver>
diff --git a/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.vcxproj b/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.vcxproj
new file mode 100644
index 00000000..4d7b340c
--- /dev/null
+++ b/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.vcxproj
@@ -0,0 +1,126 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="12.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|Arm">
+      <Configuration>Debug</Configuration>
+      <Platform>Arm</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|Arm">
+      <Configuration>Release</Configuration>
+      <Platform>Arm</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <PropertyGroup Label="Globals">
+    <ProjectGuid>{7568DCFB-C421-478A-A809-21EF6EC243BE}</ProjectGuid>
+    <RootNamespace>$(MSBuildProjectName)</RootNamespace>
+    <KMDF_VERSION_MAJOR>1</KMDF_VERSION_MAJOR>
+    <Configuration Condition="'$(Configuration)' == ''">Debug</Configuration>
+    <Platform Condition="'$(Platform)' == ''">Arm</Platform>
+    <SampleGuid>{03525FA0-7E40-493E-AAB7-D8D73FACBC51}</SampleGuid>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
+  <PropertyGroup Label="Configuration" Condition="'$(Configuration)|$(Platform)'=='Release|Arm'">
+    <TargetVersion>Windows10</TargetVersion>
+    <UseDebugLibraries>False</UseDebugLibraries>
+    <DriverTargetPlatform>Universal</DriverTargetPlatform>
+    <DriverType />
+    <PlatformToolset>WindowsApplicationForDrivers10.0</PlatformToolset>
+    <ConfigurationType>DynamicLibrary</ConfigurationType>
+  </PropertyGroup>
+  <PropertyGroup Label="Configuration" Condition="'$(Configuration)|$(Platform)'=='Debug|Arm'">
+    <TargetVersion>Windows10</TargetVersion>
+    <UseDebugLibraries>True</UseDebugLibraries>
+    <DriverTargetPlatform>Universal</DriverTargetPlatform>
+    <DriverType />
+    <PlatformToolset>WindowsApplicationForDrivers10.0</PlatformToolset>
+    <ConfigurationType>DynamicLibrary</ConfigurationType>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <PropertyGroup>
+    <OutDir>$(IntDir)</OutDir>
+  </PropertyGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Release|Arm'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" />
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Debug|Arm'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" />
+  </ImportGroup>
+  <ItemGroup Label="WrappedTaskItems" />
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Arm'">
+    <Link>
+      <EntryPointSymbol Condition="'$(Platform)'=='win32'">HalExtensionInit@12</EntryPointSymbol>
+      <EntryPointSymbol Condition="'$(Platform)'!='win32'">HalExtensionInit</EntryPointSymbol>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Arm'">
+    <Link>
+      <EntryPointSymbol Condition="'$(Platform)'=='win32'">HalExtensionInit@12</EntryPointSymbol>
+      <EntryPointSymbol Condition="'$(Platform)'!='win32'">HalExtensionInit</EntryPointSymbol>
+    </Link>
+  </ItemDefinitionGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|Arm'">
+    <TargetName>HalExtSampleDma</TargetName>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Arm'">
+    <TargetName>HalExtSampleDma</TargetName>
+  </PropertyGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Arm'">
+    <ResourceCompile>
+      <AdditionalIncludeDirectories>%(AdditionalIncludeDirectories);$(DDK_INC_PATH)</AdditionalIncludeDirectories>
+    </ResourceCompile>
+    <ClCompile>
+      <AdditionalIncludeDirectories>%(AdditionalIncludeDirectories);$(DDK_INC_PATH)</AdditionalIncludeDirectories>
+      <TreatWarningAsError>true</TreatWarningAsError>
+      <WarningLevel>Level4</WarningLevel>
+      <AdditionalOptions>%(AdditionalOptions) /J</AdditionalOptions>
+      <ExceptionHandling>
+      </ExceptionHandling>
+    </ClCompile>
+    <Midl>
+      <AdditionalIncludeDirectories>%(AdditionalIncludeDirectories);$(DDK_INC_PATH)</AdditionalIncludeDirectories>
+    </Midl>
+    <Link>
+      <AdditionalDependencies>%(AdditionalDependencies);halextlib.lib;libcntpr.lib;bufferoverflowfastfailk.lib</AdditionalDependencies>
+      <AdditionalOptions>%(AdditionalOptions)                           -merge:PAGECONST=PAGE                    -merge:INITCONST=INIT                    /LARGEADDRESSAWARE</AdditionalOptions>
+      <ModuleDefinitionFile>HalExtSampleDma.def</ModuleDefinitionFile>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Arm'">
+    <ResourceCompile>
+      <AdditionalIncludeDirectories>%(AdditionalIncludeDirectories);$(DDK_INC_PATH)</AdditionalIncludeDirectories>
+    </ResourceCompile>
+    <ClCompile>
+      <AdditionalIncludeDirectories>%(AdditionalIncludeDirectories);$(DDK_INC_PATH)</AdditionalIncludeDirectories>
+      <TreatWarningAsError>true</TreatWarningAsError>
+      <WarningLevel>Level4</WarningLevel>
+      <AdditionalOptions>%(AdditionalOptions) /J</AdditionalOptions>
+      <ExceptionHandling>
+      </ExceptionHandling>
+    </ClCompile>
+    <Midl>
+      <AdditionalIncludeDirectories>%(AdditionalIncludeDirectories);$(DDK_INC_PATH)</AdditionalIncludeDirectories>
+    </Midl>
+    <Link>
+      <AdditionalDependencies>%(AdditionalDependencies);halextlib.lib;libcntpr.lib;bufferoverflowfastfailk.lib</AdditionalDependencies>
+      <AdditionalOptions>%(AdditionalOptions)                           -merge:PAGECONST=PAGE                    -merge:INITCONST=INIT                    /LARGEADDRESSAWARE</AdditionalOptions>
+      <ModuleDefinitionFile>HalExtSampleDma.def</ModuleDefinitionFile>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemGroup>
+    <ClCompile Include="HalExtSampleDma.c" />
+    <ResourceCompile Include="HalExtSampleDma.rc" />
+  </ItemGroup>
+  <ItemGroup>
+    <Inf Exclude="@(Inf)" Include="*.inf" />
+    <FilesToPackage Include="$(TargetPath)" Condition="'$(ConfigurationType)'=='Driver' or '$(ConfigurationType)'=='DynamicLibrary'" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Exclude="@(None)" Include="*.txt;*.htm;*.html" />
+    <None Exclude="@(None)" Include="*.ico;*.cur;*.bmp;*.dlg;*.rct;*.gif;*.jpg;*.jpeg;*.wav;*.jpe;*.tiff;*.tif;*.png;*.rc2" />
+    <None Exclude="@(None)" Include="*.def;*.bat;*.hpj;*.asmx" />
+  </ItemGroup>
+  <ItemGroup>
+    <ClInclude Exclude="@(ClInclude)" Include="*.h;*.hpp;*.hxx;*.hm;*.inl;*.xsd" />
+  </ItemGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+</Project>
\ No newline at end of file
diff --git a/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.vcxproj.Filters b/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.vcxproj.Filters
new file mode 100644
index 00000000..0e78975f
--- /dev/null
+++ b/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDma.vcxproj.Filters
@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup>
+    <Filter Include="Source Files">
+      <Extensions>cpp;c;cc;cxx;def;odl;idl;hpj;bat;asm;asmx;*</Extensions>
+      <UniqueIdentifier>{C49AD628-A169-4113-A58C-7869B002B124}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="Header Files">
+      <Extensions>h;hpp;hxx;hm;inl;inc;xsd</Extensions>
+      <UniqueIdentifier>{4066A1BF-4F9E-4F43-B6C3-3DEEDE4A553C}</UniqueIdentifier>
+    </Filter>
+    <Filter Include="Resource Files">
+      <Extensions>rc;ico;cur;bmp;dlg;rc2;rct;bin;rgs;gif;jpg;jpeg;jpe;resx;tiff;tif;png;wav;mfcribbon-ms;man;xml</Extensions>
+      <UniqueIdentifier>{CD82A108-349C-4687-A02C-C816B6A47307}</UniqueIdentifier>
+    </Filter>
+  </ItemGroup>
+  <ItemGroup>
+    <ClCompile Include="HalExtSampleDma.c">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <None Include="HalExtSampleDma.def">
+      <Filter>Source Files</Filter>
+    </None>
+  </ItemGroup>
+  <ItemGroup>
+    <ResourceCompile Include="HalExtSampleDma.rc">
+      <Filter>Resource Files</Filter>
+    </ResourceCompile>
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDmaReadme.txt b/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDmaReadme.txt
new file mode 100644
index 00000000..05e44648
--- /dev/null
+++ b/general/HalExtensionSample/HalExtSampleDma/HalExtSampleDmaReadme.txt
@@ -0,0 +1,139 @@
+Copyright (c) 2011 Microsoft Corporation
+
+Author: Cody Hartwig (chartwig) 9-Jun-2011
+
+------
+
+This document describes the chDMA controller.  chDMA is a 32-channel,
+32-request line DMA controller for which a sample HAL extension has been
+implemented.  This document also describes a sample peripheral device and the
+configuration required for use with the DMA controller.
+
+General Controller Information
+==============================
+
+Base Physical Address                     0x70001000
+GSI                                       0x27
+Number of Channels                        32
+Number of Request Lines                   32
+Cache Coherent                            No
+Supports ReadDmaCounter                   Yes
+
+
+Register Layout
+===============
+
+CH_DMA_CONTROL (Offset: 0x00, RW, Reset: 0x00000000)
+--------------
+
+This register sets controller-wide settings such as controller enable.
+
+Bit              Function
+31               Controller Enable: 1-enable, 0-disable
+30-0             Reserved
+
+CH_DMA_STATUS (Offset: 0x04, RW1C, Reset: 0x00000000)
+-------------
+
+This register describes which channels are currently asserting an interrupt.
+Interrupts are cleared by writing 1 to the appropriate bit.
+
+Bit                 Function
+31                  Channel 31 interrupt status
+30                  Channel 30 interrupt status
+..
+0                   Channel 0 interrupt status
+
+CH_DMA_INTERRUPT_MASK (Offset: 0x08, RW, Reset: 0x00000000)
+---------------------
+
+A channel interrupt is unmasked by writing 1 to the corresponding bit in this
+register.
+
+Bit                 Function
+31                  Channel 31 interrupt mask
+30                  Channel 30 interrupt mask
+..
+0                   Channel 0 interrupt mask
+
+CH_DMA_CHANNEL_i_CONTROL (Offset: 0x10 + (i * 0x10), RW, Reset:0x00000000)
+------------------------
+
+This register controls per channel operation of the controller.  A transfer
+may begin once the enable bit is set.  When the enable bit is cleared, the
+current burst is finished and the transfer will stop.
+
+Bit               Function
+31                Enable
+30                Interrupt on completion
+29-28             Device Width:
+                      0b00 - 8-bit
+                      0b01 - 16-bit
+                      0b10 - 32-bit
+                      0b11 - Reserved
+27-26             Burst Size:
+                      0b00 - 1 Word
+                      0b01 - 2 Word
+                      0b10 - 4 Word
+                      0b11 - 8 Word
+25                    Flow Control: 1-enable, 0-disable
+24                    Loop: 1-repeat transfer, 0-transfer once
+23-19             Request line trigger
+18                Transfer Direction: 1-device to mem, 0-mem to device
+17-16             Reserved
+15-0              Transfer Length
+
+CH_DMA_CHANNEL_i_MEM_PTR (Offset: 0x14 + (i * 0x10), RW, Reset: 0x00000000)
+------------------------
+
+This register sets the memory-side address of the transfer.
+
+Bit               Function
+31-0              Memory-side address
+
+CH_DMA_CHANNEL_i_DEV_PTR (Offset: 0x18 + (i * 0x10), RW, Reset: 0x00000000)
+------------------------
+
+This register sets the device-side address of the transfer.
+
+Bit               Function
+31-0              Device-side address
+
+CH_DMA_CHANNEL_i_STATUS (Offset: 0x1c + (i * 0x10), RO, Reset: 0x00000000)
+-----------------------
+
+This register reports transfer status.
+
+Bit               Function
+31                Channel Busy
+30-16             Reserved
+15-0              Bytes Transferred
+
+
+
+Programming Model
+=================
+Normal operation of the DMA controller is achieved by the following steps:
+
+1. Enable the controller by writing 0x80000000 to the CH_DMA_CONTROL register.
+2. Unmask channel 0's interrupt by or'ing 0x1 with the CH_DMA_INTERRUPT_MASK
+   register
+3. Program the memory-side transfer address into the CH_DMA_CHANNEL_0_MEM_PTR
+   register.
+4. Program the device-side transfer address into the CH_DMA_CHANNEL_0_DEV_PTR
+   register.
+5. Program the CH_DMA_CHANNEL_0_CONTROL register.  This enables the channel.
+
+
+Peripheral Information
+======================
+
+For the purposes of this sample, the chDMA controller is connected to a single
+UAART.  This UART requires the following DMA controller configuration to
+work properly:
+
+Parameter              Value
+Bus Width              8 bits
+Burst Size             1 Word
+Request Line           0x15
+Flow Control           Enabled