diff -r 000000000000 -r 96e5fb8b040d kernel/eka/drivers/locmedia/dmasupport.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/kernel/eka/drivers/locmedia/dmasupport.cpp Thu Dec 17 09:24:54 2009 +0200 @@ -0,0 +1,749 @@ +// Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies). +// All rights reserved. +// This component and the accompanying materials are made available +// under the terms of the License "Eclipse Public License v1.0" +// which accompanies this distribution, and is available +// at the URL "http://www.eclipse.org/legal/epl-v10.html". +// +// Initial Contributors: +// Nokia Corporation - initial contribution. +// +// Contributors: +// +// Description: +// e32\drivers\locmedia\dmasupport.cpp +// +// + +#include +#include +#include "locmedia.h" +#include "dmasupport.h" +#include "dmasupport.inl" + +#define PHYSADDR_FAULT() Kern::Fault("TLOCDRV-PHYS-ADDR",__LINE__) + +//#define __DEBUG_DMASUP__ +#ifdef __DEBUG_DMASUP__ +#define __KTRACE_DMA(p) {p;} +#else +#define __KTRACE_DMA(p) +#endif + +TInt DDmaHelper::iPageSize; +TInt DDmaHelper::iPageSizeLog2; +TInt DDmaHelper::iPageSizeMsk; + +/****************************************************************************** + DDmaHelper + ******************************************************************************/ +const TPhysAddr KPhysMemFragmented = KPhysAddrInvalid; + +TUint32 Log2(TUint32 aVal) + { + __ASSERT_COMPILE(sizeof(TUint32) == 4); + + TUint32 bitPos=31; + + if(!(aVal >> 16)) {bitPos-=16; aVal<<=16;} + if(!(aVal >> 24)) {bitPos-=8; aVal<<=8 ;} + if(!(aVal >> 28)) {bitPos-=4; aVal<<=4 ;} + if(!(aVal >> 30)) {bitPos-=2; aVal<<=2 ;} + if(!(aVal >> 31)) {bitPos-=1;} + + return bitPos; + } + +TBool IsPowerOfTwo(TInt aNum) +// +// Returns ETrue if aNum is a power of two +// + { + return (aNum != 0 && (aNum & -aNum) == aNum); + } + +void DDmaHelper::ResetPageLists() + { + iFragLen = 0; + iFragLenRemaining = 0; + } + +DDmaHelper::DDmaHelper() + { + iPageSize = Kern::RoundToPageSize(1); + __ASSERT_ALWAYS(IsPowerOfTwo(iPageSize), PHYSADDR_FAULT()); + iPageSizeLog2 = Log2(iPageSize); + iPageSizeMsk = iPageSize-1; + } + +DDmaHelper::~DDmaHelper() + { + delete [] iPageArray; + delete [] iPageList; + if (iPhysicalPinObject) + { + NKern::ThreadEnterCS(); + Kern::DestroyPhysicalPinObject(iPhysicalPinObject); + NKern::ThreadLeaveCS(); + } + } + +/** +Constructs the DDmaHelper object + +@param aLength The maximum length of data mapped by this object. + Should be a multiple of the page size +@param aMediaBlockSize The minimum amount data that the media can transfer in read / write operations +@param aDmaAlignment The memory alignment required by the media devices DMA controller. (i.e. word aligned = 2) + +@return KErrNone,if successful; + KErrNoMemory, if unable to create Page Array's. +*/ +TInt DDmaHelper::Construct(TInt aLength, TInt aMediaBlockSize, TInt aDmaAlignment) + { + __ASSERT_ALWAYS(aMediaBlockSize > 0, PHYSADDR_FAULT()); + __ASSERT_ALWAYS(IsPowerOfTwo(aMediaBlockSize), PHYSADDR_FAULT()); + __ASSERT_ALWAYS(aLength > 0, PHYSADDR_FAULT()); + __ASSERT_ALWAYS(aLength > iPageSize, PHYSADDR_FAULT()); + + // This code assumes that the media block size (normally 512) is >= the processor's + // cache-line size (typically 32 bytes). This may not be true for future processors. + // If the cache-line size was 1024, for example, reading 512 bytes into a client's + // buffer & then calling Cache::SyncMemoryAfterDmaRead would invalidate an entire 1024 + // bytes in the user's address space. + TUint cacheLineSize = Cache::DmaBufferAlignment(); + __ASSERT_ALWAYS(IsPowerOfTwo(cacheLineSize), PHYSADDR_FAULT()); + if (cacheLineSize > (TUint) aMediaBlockSize) + return KErrNotSupported; + + //Check whether Kernel supports physical memory pinning: + TInt mm = Kern::HalFunction(EHalGroupKernel, EKernelHalMemModelInfo, 0, 0) & EMemModelTypeMask; + if (mm >= EMemModelTypeFlexible) + { + // Flexible memory model supports physical pinning for user (and Kernel) memory that + // is the subject of DMA transfer. + // Physical memory pinning ensures that: + // - physical memory is not moved by RAM defragmentation. + // - it is safe to to DMA against it or do sync cache (using new interface) even if/when + // the owner of the memory (e.g. untrusted user aplication) decomits memory or panics. + // For details @see Kern::PinPhysicalMemory. + // Cache Sync of physically pinned memory on flexible memory model is done by: + // - Cache::SyncPhysicalMemoryBeforeDmaWrite + // - Cache::SyncPhysicalMemoryBeforeDmaRead + // - Cache::SyncPhysicalMemoryAfterDmaRead + iPhysPinningAvailable = ETrue; + __KTRACE_DMA(Kern::Printf("Memory model (%d) supports physical pining\n",mm)); + NKern::ThreadEnterCS(); + TInt r=Kern::CreatePhysicalPinObject(iPhysicalPinObject); + NKern::ThreadLeaveCS(); + if (r) return r; + } + else + { + // Memory models before flexible do not support memory pinning. + // The driver has to use PrepareMemoryForDMA/ReleaseMemoryFromDMA Kernel interface + // that ensures that physical memory won't be moved by RAM defragmentation module. + // However, Kernel relies on assumption that the user memory won't dissapear (e.g. by + // user client closing the chunk or panics), as it would lead to Kernel crash. + // For that reason, the only use case for DMA transfer into user memory is File System's + // read/write buffer - as it is assumed that File System is trusted component. + // To mark its buffers(s) for DMA transfer, File Sytem must call UserSvr::RegisterTrustedChunk + // before DMA transfer starts. + // Cache sync. operations before/after DMA transfer must be done by using the old Cache interface: + // - Cache::SyncMemoryBeforeDmaWrite + // - Cache::SyncMemoryBeforeDmaRead + // - Cache::SyncMemoryAfterDmaRead + // As they all require linear address as input, these methods also rely on File System buffers + // to be in valid state during sync calls. + iPhysPinningAvailable = EFalse; + __KTRACE_DMA(Kern::Printf("Memory model (%d) doesn't support physical pining\n",mm)); + iPhysicalPinObject = NULL; + } + + iMaxPages = (aLength >> iPageSizeLog2)-1; + + // 2 Additional pages for page straddling + iPageArray = new TPhysAddr[iMaxPages+2]; + if (iPageArray != NULL) + { + iPageList = new TPageList[iMaxPages]; + if (iPageList != NULL) + { + iMediaBlockSize = aMediaBlockSize; + iMediaBlockSizeMask = TInt64(iMediaBlockSize - 1); + + iDmaAlignment = aDmaAlignment; + __KTRACE_DMA(Kern::Printf("-PHYSADDR: Construct iMaxPages(%d), MediaBlocks(%d), DMAalign(%d)",iMaxPages,iMediaBlockSize,iDmaAlignment)); + return KErrNone; + } + delete [] iPageArray; iPageArray = NULL; + } + + iMaxPages = 0; + return KErrNoMemory; + } + +/** + * Each Read/Write request is examined to determine if the descriptor that + * is referenced is mapped to a physical memory object; + * if so it prepares the memory, updates the request with physical memory information + * and issues the request. + * If a request does not make use of physical memory or is not configured correctly the + * request is passed through without modification. + */ +TInt DDmaHelper::SendReceive(TLocDrvRequest& aReq, TLinAddr aLinAddress) + { + DPrimaryMediaBase& primaryMedia = *aReq.Drive()->iPrimaryMedia; + + TInt reqId = aReq.Id(); + if (reqId != DLocalDrive::ERead && reqId != DLocalDrive::EWrite) + return aReq.SendReceive(&primaryMedia.iMsgQ); + + if ((I64HIGH(aReq.Length()) > 0) || (aReq.Length() < iMediaBlockSize)) + return aReq.SendReceive(&primaryMedia.iMsgQ); + + // If more than one user thread tries to access the drive, then bail out as there is + // only one DDmaHelper object per TLocDrv. Normally this shouldn't ever happen unless + // a client app accesses the drive directly using TBusLOcalDrive or the file system is + // asynchronous (i.e. there is a separate drive thread) but the file server message is + // flagged as synchronous - e.g. EFsDrive + if (TInt(__e32_atomic_add_ord32(&iLockCount, 1)) > 0) // busy ? + { + __KTRACE_DMA(Kern::Printf("-PHYSADDR: BUSY")); + __e32_atomic_add_ord32(&iLockCount, TUint32(-1)); + return aReq.SendReceive(&primaryMedia.iMsgQ); + } + + // make a copy of the request + iMemoryType = EUnknown; + iReq = &aReq; + iReqId = reqId; + + iReqPosClient = iReq->Pos(); + + iReqLenClient = I64LOW(iReq->Length()); + + iReqRemoteDesOffset = iReq->RemoteDesOffset(); + iReqFlags = iReq->Flags(); + + iRemoteThread = iReq->RemoteThread(); + iCurrentThread = &Kern::CurrentThread(); + iOwningThread = iRemoteThread ? iRemoteThread : iCurrentThread; + + iChunk = NULL; + iChunkOffset = 0; + iLinAddressUser = NULL; + iLenConsumed = 0; + + // point to the start of the descriptor + iLinAddressUser = aLinAddress - iReqRemoteDesOffset; + + // Need to check descriptors from both direct Clients (i.e. file cache, RemoteThread == NULL ) + // and Remote Server Clients (file server clients, RemoteThread != NULL) + // Shared Memory can potentially be used by both remote server and direct clients + NKern::ThreadEnterCS(); + iChunk = Kern::OpenSharedChunk(iOwningThread, (const TAny*) iLinAddressUser, ETrue, iChunkOffset); + NKern::ThreadLeaveCS(); + + TInt fragments = 0; + TInt r; + do + { + __KTRACE_DMA(Kern::Printf(">PHYSADDR:SendReceive() iReqLen %d; iLenConsumed %d; fragments %d",iReqLen, iLenConsumed, fragments)); + r = RequestStart(); + if (r != KErrNone) + { + if (iChunk) + { + NKern::ThreadEnterCS(); + Kern::ChunkClose(iChunk); + iChunk = NULL; + NKern::ThreadLeaveCS(); + } + __KTRACE_DMA(Kern::Printf("SendReceive(&primaryMedia.iMsgQ); + } + else + { + iReq->Flags() |= TLocDrvRequest::EPhysAddr; + } + + __KTRACE_DMA(Kern::Printf("-PHYSADDR:SendReceive() rThread %08X pos %08lX, len %d addr %08X off %08X", + iRemoteThread, iReq->Pos(), I64LOW(iReq->Length()), iLinAddressUser, iReqRemoteDesOffset)); + + __ASSERT_DEBUG(iReq->Length() == FragLength(), PHYSADDR_FAULT()); + __ASSERT_DEBUG(iReq->Length() != 0, PHYSADDR_FAULT()); + + // reinstate iValue in case overwritten by DMediaPagingDevice::CompleteRequest() + iReq->iValue = iReqId; + + r = iReq->SendReceive(&primaryMedia.iMsgQ); + + // The media driver could potentially choose to deal with the request + // without accessing physical memory (e.g. if the data is already cached). + iLenConsumed += iFragLenRemaining; + + RequestEnd(); + + ResetPageLists(); + + fragments++; + + } + while(r == KErrNone && LengthRemaining() > 0); + + if (iChunk) + { + NKern::ThreadEnterCS(); + Kern::ChunkClose(iChunk); + iChunk = NULL; + NKern::ThreadLeaveCS(); + } + + // Set remote descriptor length to iReqLenClient + if (iReqId == DLocalDrive::ERead && r == KErrNone) + r = UpdateRemoteDescriptorLength(iReqLenClient); + + __KTRACE_DMA(Kern::Printf(" + * + * The pages may not be physically contiguous; if they are not, + * then they are supplied to the media driver one contiguous + * sequent at a time by GetPhysicalAddress() + **/ +TInt DDmaHelper::RequestStart() + { + __KTRACE_DMA(Kern::Printf(">PHYSADDR:RequestStart()")); + iIndex = 0; + + TLinAddr startAddr = LinAddress(); + TInt64 startPos = iReqPosClient + iLenConsumed; + TInt mediaBlockOffset = BlockOffset(startPos); + TInt addrBlockOffset = BlockOffset(startAddr); + TInt length = Min(LengthRemaining(), MaxFragLength()); + + iPageArrayCount = iPageListCount = 0; + + TLinAddr firstPageStart = PageAlign(startAddr); + TLinAddr lastPageStart = PageAlign(startAddr + length + iPageSize - 1); + iPageArrayCount = (lastPageStart - firstPageStart + 1) >> iPageSizeLog2; + + iMemoryType = EUnknown; + iPhysAddr = KPhysMemFragmented; // Default - Mark memory as fragmented + + //************************************* + // Check Physical Page Alignment!! + //************************************* + if (!IsBlockAligned(startPos)) + { + // Will DMA align at next block alignment? such that DMA can be used + TInt ofset = I64LOW((startPos + iMediaBlockSize) & (iMediaBlockSize-1)); + ofset = iMediaBlockSize - ofset; + + if (!IsDmaAligned(startAddr)) + { + __KTRACE_DMA(Kern::Printf(" 0) ) + { + TLinAddr firstPageAddr = PageAlign(startAddr); //ensure that it is page aligned. + + TInt r = KErrNone; + if (iPhysPinningAvailable) + { + TBool readOnlyMem = (iReqId == DLocalDrive::EWrite); + r = Kern::PinPhysicalMemory(iPhysicalPinObject, firstPageAddr, iPageArrayCount << iPageSizeLog2, + readOnlyMem, iPhysAddr, iPageArray, iMapAttr, iPageColour, iCurrentThread); + } + else + { + NKern::ThreadEnterCS(); + r = Kern::PrepareMemoryForDMA(iCurrentThread, (void*)firstPageAddr, iPageArrayCount << iPageSizeLog2, iPageArray); + NKern::ThreadLeaveCS(); + } + if (r != KErrNone) + return r; + + iMemoryType = EFileServerChunk; + + __KTRACE_DMA(Kern::Printf("-PHYSADDR:RequestStart() - EFileServerChunk")); + } + //**************************** + // Is it shared chunk ? + //**************************** + else if (iChunk) + { + // calculate chunk offset of start of first page + TInt offset = iChunkOffset + iReqRemoteDesOffset+ iLenConsumed; + + TInt r = Kern::ChunkPhysicalAddress(iChunk, offset, length, iLinAddressKernel, iMapAttr, iPhysAddr, iPageArray); + + if (r < KErrNone) + return r; // 0 = Contiguous Memory, 1 = Fragmented/Dis-Contiguous Memory + + iMemoryType = ESharedChunk; + + __KTRACE_DMA(Kern::Printf("-PHYSADDR:RequestStart() - ESharedChunk")); + } + else + { + __KTRACE_DMA(Kern::Printf("Length() = MAKE_TINT64(0, length); + iReq->Pos() = iReqPosClient + iLenConsumed; + iReq->RemoteDesOffset() = iReqRemoteDesOffset + iLenConsumed; + // restore EAdjusted flag to ensure iReq->Pos() is adjusted correctly + iReq->Flags()&= ~TLocDrvRequest::EAdjusted; + iReq->Flags()|= (iReqFlags & TLocDrvRequest::EAdjusted); + + //************************************************ + // Sync memory + //************************************************ + __KTRACE_DMA(Kern::Printf(">SYNC-PHYSADDR:addr 0x%x len %d", startAddr, length)); + + // Only sync whole blocks: it is assumed that the media driver will transfer + // partial start and end blocks without DMA + + TInt startBlockPartialLen = IsBlockAligned(startPos) ? 0 : iMediaBlockSize - BlockOffset(startPos); + TInt blockLen = (TInt) BlockAlign(length - startBlockPartialLen); + + if (iReqId == DLocalDrive::EWrite) + { + if (iMemoryType == ESharedChunk) + { + Cache::SyncMemoryBeforeDmaWrite(iLinAddressKernel+startBlockPartialLen, blockLen, iMapAttr); + } + else // (iMemoryType == EFileServerChunk) + { + if (iPhysPinningAvailable) + Cache::SyncPhysicalMemoryBeforeDmaWrite(iPageArray, iPageColour, startBlockPartialLen, blockLen, iMapAttr); + else + Cache::SyncMemoryBeforeDmaWrite(startAddr+startBlockPartialLen, blockLen); + } + } + else + { + if (iMemoryType == ESharedChunk) + Cache::SyncMemoryBeforeDmaRead(iLinAddressKernel, length, iMapAttr); + else // (iMemoryType == EFileServerChunk) + { + if (iPhysPinningAvailable) + Cache::SyncPhysicalMemoryBeforeDmaRead(iPageArray, iPageColour, 0, length, iMapAttr); + else + Cache::SyncMemoryBeforeDmaRead(startAddr, length); + } + } + + __KTRACE_DMA(Kern::Printf("PHYSADDR:RequestEnd()")); + + __ASSERT_DEBUG(iReqId == DLocalDrive::ERead || iReqId == DLocalDrive::EWrite, PHYSADDR_FAULT()); + __ASSERT_DEBUG(iMemoryType == ESharedChunk || iMemoryType == EFileServerChunk, PHYSADDR_FAULT()); + + TInt length = FragLength(); // len of data just transferred + TLinAddr startAddr = LinAddress() - length; + + // Sync the memory : but not if the media driver has decided to transfer ALL the data using IPC rather than DMA. + // It is assumed that the media driver will transfer partial start & end blocks using IPC, but it may also choose + // to use IPC for the ENTIRE fragment when read/writing at the end of the media (see medmmc.cpp) + if (iFragLenRemaining < length && iReqId == DLocalDrive::ERead) + { + TInt64 startPos = iReq->Pos(); + TInt startBlockPartialLen = IsBlockAligned(startPos) ? 0 : iMediaBlockSize - BlockOffset(startPos); + TInt blockLen = (TInt) BlockAlign(length - startBlockPartialLen); + + if (iMemoryType == ESharedChunk) + { + Cache::SyncMemoryAfterDmaRead(iLinAddressKernel + startBlockPartialLen, blockLen); + } + else // (iMemoryType == EFileServerChunk) + { + if (iPhysPinningAvailable) + Cache::SyncPhysicalMemoryAfterDmaRead(iPageArray, iPageColour, startBlockPartialLen, blockLen, iMapAttr); + else + Cache::SyncMemoryAfterDmaRead(startAddr + startBlockPartialLen, blockLen); + } + + } + ReleasePages(PageAlign(startAddr)); + } + +/** + * For File Server chunks this method releases the current physical memory in use. + * + * @see Kern::ReleaseMemoryFromDMA() + */ +void DDmaHelper::ReleasePages(TLinAddr aAddr) + { + if (iMemoryType == EFileServerChunk) + { + __KTRACE_DMA(Kern::Printf(">PHYSADDR():ReleasePages thread (0x%x) aAddr(0x%08x) size(%d) iPageArray(0x%x)",iCurrentThread, aAddr, (iPageArrayCount << iPageSizeLog2), iPageArray)); + + TInt r; + if (iPhysPinningAvailable) + { + r = Kern::UnpinPhysicalMemory(iPhysicalPinObject); + } + else + { + NKern::ThreadEnterCS(); + r = Kern::ReleaseMemoryFromDMA(iCurrentThread, (void*) aAddr, iPageArrayCount << iPageSizeLog2, iPageArray); + NKern::ThreadLeaveCS(); + } + __ASSERT_ALWAYS(r == KErrNone, PHYSADDR_FAULT()); + } + } + +/** + * Utility method which examines the page array, compiling adjacent pages into contiguous fragments + * and populating iPageList with said fragments. + */ +void DDmaHelper::BuildPageList() + { + iPageListCount = 0; + + if (iPhysAddr != KPhysMemFragmented) + { + __KTRACE_DMA(Kern::Printf(">PHYSADDR:BuildPageList() - Contiguous Memory")); + // Only one entry required. + iPageList[0].iAddress = iPhysAddr; + iPageList[0].iLength = FragLength(); + iPageListCount = 1; + } + else + { + __KTRACE_DMA(Kern::Printf(">PHYSADDR:BuildPageList() - Dis-Contiguous Memory")); + TInt offset; + + offset = PageOffset(iChunkOffset + iReqRemoteDesOffset+ iLenConsumed); + iPageList[0].iAddress = iPageArray[0]+offset; + iPageList[0].iLength = iPageSize-offset; + + TInt lengthRemaining = FragLength() - iPageList[0].iLength; + + TInt i =1; + for( ; i < iPageArrayCount; i++) + { + //Check if RAM pages are physically adjacent + if ((iPageArray[i-1] + PageSize()) == iPageArray[i]) + { + // Adjacent pages - just add length + iPageList[iPageListCount].iLength += PageSize(); + } + else + { + // Not Adjacent, start new Memory fragment + iPageListCount++; + iPageList[iPageListCount].iAddress = iPageArray[i]; + iPageList[iPageListCount].iLength = iPageSize; + } + + lengthRemaining -= PageSize(); + if (lengthRemaining < 0) + { + // Last page, re-adjust length for odd remainder. + iPageList[iPageListCount].iLength += lengthRemaining; + break; + } + } + + iPageListCount++; + } + +//#ifdef __DEBUG_DMASUP__ +// for (TInt m=0; m= iPageListCount) + { + __KTRACE_DMA(Kern::Printf(">PHYSADDR:GetPhysD() [%d], PageListCount:%d", iIndex, iPageListCount)); + aAddr = 0; + aLen = 0; + return KErrGeneral; + } + + aAddr = iPageList[iIndex].iAddress; + aLen = iPageList[iIndex].iLength; + iLenConsumed+= aLen; + iFragLenRemaining-= aLen; + + __KTRACE_DMA(Kern::Printf(">PHYSADDR:GetPhysD() [%d] addr:0x%08X, l:%d; Used:%d, Left:%d", iIndex, aAddr, aLen, iLenConsumed, iFragLenRemaining)); + __ASSERT_DEBUG(aLen >= 0, PHYSADDR_FAULT()); + + iIndex++; //Move index to next page + + return KErrNone; + } + + +#ifdef __DEMAND_PAGING__ +/** + * Returns Address and Length of next contiguous Physical memory. + * Static function specifically for Demand Paging support + * + * @param aReq TLocDrvRequest from which physical + * @param aAddr Populated with the Physical Address of the Request aReq. + * @param aLen Populated with the length in bytes of the memory. + * + * @return KErrNone + */ +TInt DDmaHelper::GetPhysicalAddress(TLocDrvRequest& aReq, TPhysAddr& aAddr, TInt& aLen) + { + __ASSERT_DEBUG( (aReq.Flags() & TLocDrvRequest::ETClientBuffer) == 0, PHYSADDR_FAULT()); + TLinAddr linAddr = (TLinAddr) aReq.RemoteDes(); + TInt& offset = aReq.RemoteDesOffset(); + TLinAddr currLinAddr = linAddr + offset; + TInt reqLen = I64LOW(aReq.Length()); + __ASSERT_DEBUG(I64HIGH(aReq.Length()) == 0, PHYSADDR_FAULT()); + + aAddr = Epoc::LinearToPhysical(currLinAddr); + + // Set the initial length to be the length remaining in this page or the request length (whichever is shorter). + // If there are subsequent pages, we then need to determine whether they are contiguous + aLen = Min( (TInt) (PageAlign(currLinAddr+iPageSize) - currLinAddr), reqLen - offset); + + __ASSERT_DEBUG(aLen > 0, PHYSADDR_FAULT()); + + TPhysAddr currPhysPageAddr = PageAlign((TLinAddr) aAddr); + + offset+= aLen; + + + while (offset < reqLen) + { + TPhysAddr nextPhysPageAddr = Epoc::LinearToPhysical(linAddr + offset); + __ASSERT_DEBUG(PageOffset((TLinAddr) nextPhysPageAddr) == 0, PHYSADDR_FAULT()); + + if (nextPhysPageAddr != currPhysPageAddr + iPageSize) + break; + + currPhysPageAddr = nextPhysPageAddr; + + TInt len = Min(iPageSize, reqLen - offset); + offset+= len; + aLen+= len; + } + + + __KTRACE_DMA(Kern::Printf(">PHYSADDR:DP:GetPhysS(), linAddr %08X, physAddr %08X, len %x reqLen %x", linAddr + offset, aAddr, aLen, reqLen)); + + return KErrNone; + } +#endif // (__DEMAND_PAGING__) + + +/** + * Modifies the current requests remote descriptor length + * + * @param aLength Length in bytes to which the descriptor is to be set. + * + * @return KErrNone, if successful; + * KErrBadDescriptor, if descriptor is corrupted; + * otherwise one of the other system wide error codes. + */ + +TInt DDmaHelper::UpdateRemoteDescriptorLength(TInt aLength) + { + __KTRACE_DMA(Kern::Printf(">PHYSADDR:UpDesLen(%d)",aLength)); + + // Restore request Id (overwritten by KErrNone return code) to stop ASSERT in WriteRemote + iReq->Id() = DLocalDrive::ERead; + + // restore caller's descriptor offset + iReq->RemoteDesOffset() = iReqRemoteDesOffset; + + // Write a zero length descriptor at the end such that the descriptors length is correctly updated. + TPtrC8 zeroDes(NULL, 0); + TInt r = iReq->WriteRemote(&zeroDes, aLength); + + // restore return code + iReq->iValue = KErrNone; + + return r; + } +