[apple/xnu.git] / iokit / Kernel / IOInterleavedMemoryDescriptor.cpp

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 * Please obtain a copy of the License at
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#include <IOKit/IOLib.h>
#include <IOKit/IOInterleavedMemoryDescriptor.h>

#define super IOMemoryDescriptor
OSDefineMetaClassAndStructors(IOInterleavedMemoryDescriptor, IOMemoryDescriptor)

IOInterleavedMemoryDescriptor * IOInterleavedMemoryDescriptor::withCapacity(
        IOByteCount           capacity,
        IODirection           direction )
{
        //
        // Create a new IOInterleavedMemoryDescriptor.  The "buffer" will be made up
        // of several memory descriptors, that are to be chained end-to-end to make up
        // a single memory descriptor.
        //

        IOInterleavedMemoryDescriptor * me = new IOInterleavedMemoryDescriptor;

        if (me && !me->initWithCapacity(
                    /* capacity  */ capacity,
                    /* direction */ direction )) {
                me->release();
                me = NULL;
        }

        return me;
}

bool
IOInterleavedMemoryDescriptor::initWithCapacity(
        IOByteCount           capacity,
        IODirection           direction )
{
        //
        // Initialize an IOInterleavedMemoryDescriptor. The "buffer" will be made up
        // of several memory descriptors, that are to be chained end-to-end to make up
        // a single memory descriptor.
        //

        assert(capacity);

        // Ask our superclass' opinion.
        if (super::init() == false) {
                return false;
        }

        // Initialize our minimal state.

        _flags                  = direction;
#ifndef __LP64__
        _direction              = (IODirection) (_flags & kIOMemoryDirectionMask);
#endif /* !__LP64__ */
        _length                 = 0;
        _mappings               = NULL;
        _tag                    = 0;
        _descriptorCount        = 0;
        _descriptors            = IONew(IOMemoryDescriptor *, capacity);
        _descriptorOffsets      = IONew(IOByteCount, capacity);
        _descriptorLengths      = IONew(IOByteCount, capacity);

        if ((_descriptors == NULL) || (_descriptorOffsets == NULL) || (_descriptorLengths == NULL)) {
                return false;
        }

        _descriptorCapacity     = capacity;

        return true;
}

void
IOInterleavedMemoryDescriptor::clearMemoryDescriptors( IODirection direction )
{
        UInt32 index;

        for (index = 0; index < _descriptorCount; index++) {
                if (_descriptorPrepared) {
                        _descriptors[index]->complete(getDirection());
                }

                _descriptors[index]->release();
                _descriptors[index] = NULL;

                _descriptorOffsets[index] = 0;
                _descriptorLengths[index] = 0;
        }

        if (direction != kIODirectionNone) {
                _flags = (_flags & ~kIOMemoryDirectionMask) | direction;
#ifndef __LP64__
                _direction = (IODirection) (_flags & kIOMemoryDirectionMask);
#endif /* !__LP64__ */
        }

        _descriptorCount = 0;
        _length = 0;
        _mappings = NULL;
        _tag = 0;
};

bool
IOInterleavedMemoryDescriptor::setMemoryDescriptor(
        IOMemoryDescriptor * descriptor,
        IOByteCount offset,
        IOByteCount length )
{
        if (_descriptorPrepared || (_descriptorCount == _descriptorCapacity)) {
                return false;
        }

        if ((offset + length) > descriptor->getLength()) {
                return false;
        }

//    if ( descriptor->getDirection() != getDirection() )
//        return false;

        descriptor->retain();
        _descriptors[_descriptorCount] = descriptor;
        _descriptorOffsets[_descriptorCount] = offset;
        _descriptorLengths[_descriptorCount] = length;

        _descriptorCount++;

        _length += length;

        return true;
}

void
IOInterleavedMemoryDescriptor::free()
{
        //
        // Free all of this object's outstanding resources.
        //

        if (_descriptors) {
                for (unsigned index = 0; index < _descriptorCount; index++) {
                        _descriptors[index]->release();
                }

                if (_descriptors != NULL) {
                        IODelete(_descriptors, IOMemoryDescriptor *, _descriptorCapacity);
                }

                if (_descriptorOffsets != NULL) {
                        IODelete(_descriptorOffsets, IOMemoryDescriptor *, _descriptorCapacity);
                }

                if (_descriptorLengths != NULL) {
                        IODelete(_descriptorLengths, IOMemoryDescriptor *, _descriptorCapacity);
                }
        }

        super::free();
}

IOReturn
IOInterleavedMemoryDescriptor::prepare(IODirection forDirection)
{
        //
        // Prepare the memory for an I/O transfer.
        //
        // This involves paging in the memory and wiring it down for the duration
        // of the transfer.  The complete() method finishes the processing of the
        // memory after the I/O transfer finishes.
        //

        unsigned index;
        IOReturn status = kIOReturnSuccess;
        IOReturn statusUndo;

        if (forDirection == kIODirectionNone) {
                forDirection = getDirection();
        }

        for (index = 0; index < _descriptorCount; index++) {
                status = _descriptors[index]->prepare(forDirection);
                if (status != kIOReturnSuccess) {
                        break;
                }
        }

        if (status != kIOReturnSuccess) {
                for (unsigned indexUndo = 0; indexUndo < index; indexUndo++) {
                        statusUndo = _descriptors[index]->complete(forDirection);
                        assert(statusUndo == kIOReturnSuccess);
                }
        }

        if (status == kIOReturnSuccess) {
                _descriptorPrepared = true;
        }

        return status;
}

IOReturn
IOInterleavedMemoryDescriptor::complete(IODirection forDirection)
{
        //
        // Complete processing of the memory after an I/O transfer finishes.
        //
        // This method shouldn't be called unless a prepare() was previously issued;
        // the prepare() and complete() must occur in pairs, before and after an I/O
        // transfer.
        //

        IOReturn status;
        IOReturn statusFinal = kIOReturnSuccess;

        if (forDirection == kIODirectionNone) {
                forDirection = getDirection();
        }

        for (unsigned index = 0; index < _descriptorCount; index++) {
                status = _descriptors[index]->complete(forDirection);
                if (status != kIOReturnSuccess) {
                        statusFinal = status;
                }
                assert(status == kIOReturnSuccess);
        }

        _descriptorPrepared = false;

        return statusFinal;
}

addr64_t
IOInterleavedMemoryDescriptor::getPhysicalSegment(
        IOByteCount   offset,
        IOByteCount * length,
        IOOptionBits  options )
{
        //
        // This method returns the physical address of the byte at the given offset
        // into the memory,  and optionally the length of the physically contiguous
        // segment from that offset.
        //

        addr64_t pa;

        assert(offset <= _length);

        for (unsigned index = 0; index < _descriptorCount; index++) {
                if (offset < _descriptorLengths[index]) {
                        pa = _descriptors[index]->getPhysicalSegment(_descriptorOffsets[index] + offset, length, options);
                        if ((_descriptorLengths[index] - offset) < *length) {
                                *length = _descriptorLengths[index] - offset;
                        }
                        return pa;
                }
                offset -= _descriptorLengths[index];
        }

        if (length) {
                *length = 0;
        }

        return 0;
}