///////////////////////////////////////////////////////////////////////////////
//
//    (C) Copyright 1995 - 1997 OSR Open Systems Resources, Inc.
//    All Rights Reserved
//
//    This sofware is supplied for instructional purposes only.
//
//    OSR Open Systems Resources, Inc. (OSR) expressly disclaims any warranty
//    for this software.  THIS SOFTWARE IS PROVIDED  "AS IS" WITHOUT WARRANTY
//    OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING, WITHOUT LIMITATION,
//    THE IMPLIED WARRANTIES OF MECHANTABILITY OR FITNESS FOR A PARTICULAR
//    PURPOSE.  THE ENTIRE RISK ARISING FROM THE USE OF THIS SOFTWARE REMAINS
//    WITH YOU.  OSR's entire liability and your exclusive remedy shall not
//    exceed the price paid for this material.  In no event shall OSR or its
//    suppliers be liable for any damages whatsoever (including, without
//    limitation, damages for loss of business profit, business interruption,
//    loss of business information, or any other pecuniary loss) arising out
//    of the use or inability to use this software, even if OSR has been
//    advised of the possibility of such damages.  Because some states/
//    jurisdictions do not allow the exclusion or limitation of liability for
//    consequential or incidental damages, the above limitation may not apply
//    to you.
//
//    OSR Open Systems Resources, Inc.
//    105 Route 101A Suite 19
//    Amherst, NH 03031  (603) 595-6500 FAX: (603) 595-6503
//    email bugs to: bugs@osr.com
//
//                       
//    MODULE:
//
//        READ_WRITE.C
//
//    ABSTRACT:
//
//      This file contains read and write routines used by the
//      PCI Busmaster DMA device driver for the AMCC 5933 chip.
//
//    AUTHOR(S):
//
//        OSR Open Systems Resources, Inc.
// 
//    REVISION:   
//
//
///////////////////////////////////////////////////////////////////////////////

#include "osr-pci.h"

//
// forward declarations
//
BOOLEAN OsrStartReadOnDevice(IN PVOID SynchronizeContext);
BOOLEAN OsrStartWriteOnDevice(IN PVOID SynchronizeContext);

IO_ALLOCATION_ACTION  OsrAdapterControlRead(IN PDEVICE_OBJECT DeviceObject,
                                IN PIRP NotUsed, IN PVOID MapRegisterBase,
                                IN PVOID Context);
IO_ALLOCATION_ACTION  OsrAdapterControlWrite(IN PDEVICE_OBJECT DeviceObject,
                                IN PIRP NotUsed, IN PVOID MapRegisterBase,
                                IN PVOID Context);

///////////////////////////////////////////////////////////////////////////////
//
//  OsrWrite
//
//    This is the write dispatch entry point for the driver, called when the
//    I/O Manager has an IRP_MJ_WRITE request for the driver to process.
//
//  INPUTS:
//
//      DeviceObject - Address of the DEVICE_OBJECT for our device.
//  
//    Irp - Address of the IRP representing the IRP_MJ_WRITE call.
//
//  OUTPUTS:
//
//      None.
//
//  RETURNS:
//
//    STATUS_PENDING, since we are putting the IRP on our internal queue.
//
//  IRQL:
//
//    This routine is called at IRQL_PASSIVE_LEVEL.
//
//  NOTES:
//
//    Since we set the DO_DIRECT_IO bit in the Device Object, all buffers
//    passed to us will have been probed and locked and described by an MDL.
//    The I/O manager will provides us the MDL address in Irp->MdlAddress.
//
///////////////////////////////////////////////////////////////////////////////
NTSTATUS OsrWrite(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
    POSR_DEVICE_EXT devExt = DeviceObject->DeviceExtension;
    KIRQL oldIrql;
    NTSTATUS code = STATUS_SUCCESS;
    BOOLEAN listWasEmpty;
    PIO_STACK_LOCATION ioStack;
    ULONG temp;
            
#if DBG
    DbgPrint("OsrWrite: entered\n");
#endif

    //
    // Validate the IRP we've received
    //
    ioStack = IoGetCurrentIrpStackLocation(Irp);

    //
    // If the length of the requested transfer is either zero or too long,
    // we immediately compelte the IRP with an error status.
    //
    if (ioStack->Parameters.Write.Length == 0 ||
        ioStack->Parameters.Write.Length > OSR_PCI_MAX_TXFER)  {
            
        Irp->IoStatus.Status = STATUS_INVALID_USER_BUFFER;
        Irp->IoStatus.Information = 0;

        IoCompleteRequest(Irp, IO_NO_INCREMENT);

        return(STATUS_INVALID_USER_BUFFER);

    }
    
    // Take out the Write list lock, since we'll insert this IRP
    // onto the write queue
    //
    KeAcquireSpinLock(&devExt->WriteQueueLock, &oldIrql);

    //
    // Since we'll probably be queuing this request, set a routine 
    // to be called by the I/O Manager in case he needs to cancel
    // this IRP.
    //
    IoSetCancelRoutine(Irp, OsrCancelFromWriteQueue);

    //
    // Before we queue this request, has it been cancelled??
    //
    // What we're doing here is closing that tiny window between the time
    // the Dispatch routine is called and when we acquired the queue spin
    // lock.  Once the queue spin lock is held, and the IRP is queued, the
    // cancellation routine will deal with any requests to cancel the IRP.
    //
    if (Irp->Cancel)  {
        
        //
        // Can't complete a request with a valid cancel routine!
        //
        // TECHNICAL ERRATA: Page 466, Example 17.5 has the following
        // line, which is obviously in error:
        //
        // IoSetCancelRoutine(Irp, OsrCancelFromWriteQueue);
        // 
        // This line SHOULD READ:
        //
        IoSetCancelRoutine(Irp, NULL);
         
        KeReleaseSpinLock(&devExt->WriteQueueLock, oldIrql);

        Irp->IoStatus.Status = STATUS_CANCELLED;
        Irp->IoStatus.Information = 0;

        IoCompleteRequest(Irp, IO_NO_INCREMENT);

        return(STATUS_CANCELLED);
    }

    //
    // If we get this far, we will return with this request pending
    //
    IoMarkIrpPending(Irp);

    //
    // Do we need to start this request on the device?
    //
    // If there is no IRP currently in progress, we'll start the
    // one we've just received.
    //
    if (devExt->CurrentWriteIrp == NULL)  {
                
        //
        // No write presently active.  Start this request...
        // (Note that we're still holding the queue lock here)
        //
        OsrStartWriteIrp(DeviceObject,Irp);

    } else {

        //
        // Put this request on the end of the write queue
        //
        InsertTailList(&devExt->WriteQueue, &Irp->Tail.Overlay.ListEntry);

    }

    //
    // We're done playing with the write queue now
    //
    KeReleaseSpinLock(&devExt->WriteQueueLock, oldIrql);
    
#if DBG
    DbgPrint("OsrWrite: exiting\n");
#endif

    return(STATUS_PENDING);
}

///////////////////////////////////////////////////////////////////////////////
//
//  OsrRead
//
//    This is the read dispatch entry point for the driver, called when the
//    I/O Manager has an IRP_MJ_READ request for the driver to process.
//
//  INPUTS:
//
//      DeviceObject - Address of the DEVICE_OBJECT for our device.
//  
//    Irp - Address of the IRP representing the IRP_MJ_READ call.
//
//  OUTPUTS:
//
//      None.
//
//  RETURNS:
//
//    STATUS_PENDING, since we are putting the IRP on our internal queue.
//
//  IRQL:
//
//    This routine is called at IRQL_PASSIVE_LEVEL.
//
//  NOTES:
//
//    Since we set the DO_DIRECT_IO bit in the Device Object, all buffers
//    passed to us will have been probed and locked and described by an MDL.
//    The I/O manager will provides us the MDL address in Irp->MdlAddress.
//
///////////////////////////////////////////////////////////////////////////////
NTSTATUS OsrRead(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
    POSR_DEVICE_EXT devExt = DeviceObject->DeviceExtension;
    KIRQL oldIrql;
    NTSTATUS code = STATUS_SUCCESS;
    BOOLEAN listWasEmpty;
    PIO_STACK_LOCATION ioStack;
    ULONG temp;
            
#if DBG
    DbgPrint("OsrRead: entered\n");
#endif

    //
    // Validate the IRP we've received
    //
    ioStack = IoGetCurrentIrpStackLocation(Irp);

    //
    // If the length of the requested transfer is either zero or too long,
    // we immediately compelte the IRP with an error status.
    //
    if (ioStack->Parameters.Read.Length == 0 ||
        ioStack->Parameters.Read.Length > OSR_PCI_MAX_TXFER)  {
            
        Irp->IoStatus.Status = STATUS_INVALID_USER_BUFFER;
        Irp->IoStatus.Information = 0;

        IoCompleteRequest(Irp, IO_NO_INCREMENT);

        return(STATUS_INVALID_USER_BUFFER);

    }

    //
    // Get the Read Queue lock, so we can insert our IRP
    //
    KeAcquireSpinLock(&devExt->ReadQueueLock, &oldIrql);

    //
    // Since we'll probably be queuing this request, set a routine 
    // to be called by the I/O Manager in case he needs to cancel
    // this IRP.
    //
    IoSetCancelRoutine(Irp, OsrCancelFromReadQueue);

    //
    // Do we need to cancel this IRP, instead of queue it?
    //
    if (Irp->Cancel)  {
        
        //
        // Can't complete a request with a valid cancel routine!
        //
        IoSetCancelRoutine(Irp, NULL);
    
        KeReleaseSpinLock(&devExt->ReadQueueLock, oldIrql);

        Irp->IoStatus.Status = STATUS_CANCELLED;
        Irp->IoStatus.Information = 0;

        IoCompleteRequest(Irp, IO_NO_INCREMENT);

        return(STATUS_CANCELLED);
    }

    //
    // We'll be returning with this request pending
    //
    IoMarkIrpPending(Irp);

    //
    // Do we need to start this request on the device?
    //
    // If there is no IRP currently in progress, we'll start the
    // one we've just received.
    //
    if (devExt->CurrentReadIrp == NULL)  {
                
        //
        // No read operation presently active.  Start this request...
        // (Note that we're still holding the queue lock here)
        //
        OsrStartReadIrp(DeviceObject,Irp);

    } else {

        //
        // Put this request on the end of the write queue
        //
        InsertTailList(&devExt->ReadQueue, &Irp->Tail.Overlay.ListEntry);

    }

    //
    // We're done
    //
    KeReleaseSpinLock(&devExt->ReadQueueLock, oldIrql);
    
#if DBG
    DbgPrint("OsrRead: exiting\n");
#endif

      return(STATUS_PENDING);
}

///////////////////////////////////////////////////////////////////////////////
//
//  OsrStartWriteIrp
//
//    This is routine is called by the OsrWrite and DpcForIsr routine to
//    start a new Write operation.  The request started is the IRP located
//    at the head of the write queue.
//
//  INPUTS:
//
//      DeviceObject - Address of the DEVICE_OBJECT for our device.
//  
//      Irp - Address of the IRP representing the IRP_MJ_WRITE call.
//
//  OUTPUTS:
//
//      None.
//
//  RETURNS:
//
//      None.
//
//  IRQL:
//
//      This routine is called at IRQL_DISPATCH_LEVEL.
//
//  NOTES:
//      *** Called (and returns) with the WriteQueueLock held.
//
///////////////////////////////////////////////////////////////////////////////
VOID
OsrStartWriteIrp(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
    POSR_DEVICE_EXT devExt = DeviceObject->DeviceExtension;
    PIO_STACK_LOCATION ioStack;
    ULONG mapRegsNeeded;
    
    ioStack = IoGetCurrentIrpStackLocation(Irp);

    //
    // In progress IRPs cannot be cancelled
    //
    IoSetCancelRoutine(Irp, NULL);

#if DBG
    DbgPrint("OsrWrite: Transfer length %d.\n",
                                ioStack->Parameters.Write.Length);
#endif

    //
    // There is no in-progress request.  Start this request on the
    // device.
    //
    devExt->CurrentWriteIrp = Irp;

    devExt->WriteTotalLength = ioStack->Parameters.Write.Length;

    devExt->WriteSoFar = 0;

    devExt->WriteStartingOffset = 0;

    //
    // Start the watchdog timer on this IRP
    //
    (ULONG)Irp->Tail.Overlay.DriverContext[0] = OSR_WATCHDOG_INTERVAL;

    //
    // Since we're about to initiate a DMA operation, ensure the user's data
    // buffer is flushed from the cache back into memory, on processors that
    // are non-DMA cache coherent.
    //
    KeFlushIoBuffers(Irp->MdlAddress, FALSE, TRUE);

    //
    // Determine the number of map registers we'll need for this transfer
    //
    mapRegsNeeded = 
        ADDRESS_AND_SIZE_TO_SPAN_PAGES(MmGetMdlVirtualAddress(Irp->MdlAddress),
                                        ioStack->Parameters.Write.Length);
        
#if DBG
    DbgPrint("StartWrite: %d. map regs needed\n", mapRegsNeeded);
#endif

    //
    // If the number of map registers required for this transfer exceeds the
    // maximum we're allowed to use (as reported to us from HalGetAdapter() ),
    // we'll need to limit ourselves to the maximum we're allowed.
    //
    devExt->MapRegsThisWrite = ((mapRegsNeeded > devExt->WriteMapRegsGot) ? 
                              devExt->WriteMapRegsGot : mapRegsNeeded);

#if DBG
    DbgPrint("StartWrite: %d. map regs this xfer\n", devExt->MapRegsThisWrite);
#endif

    //
    // Ready to GO! Allocate the appropriate Adapter Object and map registers.
    //
    IoAllocateAdapterChannel(devExt->WriteAdapter,
                             DeviceObject, 
                             devExt->MapRegsThisWrite,
                             OsrAdapterControlWrite,
                             Irp);
}


///////////////////////////////////////////////////////////////////////////////
//
//  OsrStartReadIrp
//
//    This is routine is called by the OsrRead and Dpc routine in order to
//    begin a new Read operation.
//
//  INPUTS:
//
//      DeviceObject - Address of the DEVICE_OBJECT for our device.
//  
//      Irp - Address of the IRP representing the IRP_MJ_READ call.
//
//  OUTPUTS:
//
//      None.
//
//  RETURNS:
//
//      None.
//
//  IRQL:
//
//      This routine is called at IRQL_DISPATCH_LEVEL.