changeset 2344c9dcc0d6 in /z/repo/gem5
details: http://repo.gem5.org/gem5?cmd=changeset;node=2344c9dcc0d6
description:
dev: Add a DmaCallback class to DmaDevice
This patch introduces the DmaCallback helper class, which registers a
callback
to fire after a sequence of (potentially non-contiguous) DMA transfers
on a
DmaPort completes.
diffstat:
src/dev/dma_device.hh | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 85 insertions(+), 0 deletions(-)
diffs (95 lines):
diff -r 9796e43e751d -r 2344c9dcc0d6 src/dev/dma_device.hh
--- a/src/dev/dma_device.hh Tue Sep 13 23:12:46 2016 -0400
+++ b/src/dev/dma_device.hh Tue Sep 13 23:14:24 2016 -0400
@@ -185,6 +185,91 @@
};
/**
+ * DMA callback class.
+ *
+ * Allows one to register for a callback event after a sequence of (potentially
+ * non-contiguous) DMA transfers on a DmaPort completes. Derived classes must
+ * implement the process() method and use getChunkEvent() to allocate a
+ * callback event for each participating DMA.
+ */
+class DmaCallback : public Drainable
+{
+ public:
+ virtual const std::string name() const { return "DmaCallback"; }
+
+ /**
+ * DmaPort ensures that all oustanding DMA accesses have completed before
+ * it finishes draining. However, DmaChunkEvents scheduled with a delay
+ * might still be sitting on the event queue. Therefore, draining is not
+ * complete until count is 0, which ensures that all outstanding
+ * DmaChunkEvents associated with this DmaCallback have fired.
+ */
+ DrainState drain() override
+ {
+ return count ? DrainState::Draining : DrainState::Drained;
+ }
+
+ protected:
+ int count;
+
+ DmaCallback()
+ : count(0)
+ { }
+
+ virtual ~DmaCallback() { }
+
+ /**
+ * Callback function invoked on completion of all chunks.
+ */
+ virtual void process() = 0;
+
+ private:
+ /**
+ * Called by DMA engine completion event on each chunk completion.
+ * Since the object may delete itself here, callers should not use
+ * the object pointer after calling this function.
+ */
+ void chunkComplete()
+ {
+ if (--count == 0) {
+ process();
+ // Need to notify DrainManager that this object is finished
+ // draining, even though it is immediately deleted.
+ signalDrainDone();
+ delete this;
+ }
+ }
+
+ /**
+ * Event invoked by DmaDevice on completion of each chunk.
+ */
+ class DmaChunkEvent : public Event
+ {
+ private:
+ DmaCallback *callback;
+
+ public:
+ DmaChunkEvent(DmaCallback *cb)
+ : Event(Default_Pri, AutoDelete), callback(cb)
+ { }
+
+ void process() { callback->chunkComplete(); }
+ };
+
+ public:
+
+ /**
+ * Request a chunk event. Chunks events should be provided to each DMA
+ * request that wishes to participate in this DmaCallback.
+ */
+ Event *getChunkEvent()
+ {
+ ++count;
+ return new DmaChunkEvent(this);
+ }
+};
+
+/**
* Buffered DMA engine helper class
*
* This class implements a simple DMA engine that feeds a FIFO
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