1 files changed, 606 insertions, 0 deletions
diff --git a/drivers/staging/hv/RingBuffer.c b/drivers/staging/hv/RingBuffer.c
new file mode 100644
index 000000000000..f69ae33a91e3
--- /dev/null
+++ b/drivers/staging/hv/RingBuffer.c
@@ -0,0 +1,606 @@
+/*
+ *
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include "osd.h"
+#include "logging.h"
+#include "RingBuffer.h"
+
+
+/* #defines */
+
+
+/* Amount of space to write to */
+#define BYTES_AVAIL_TO_WRITE(r, w, z) ((w) >= (r))?((z) - ((w) - (r))):((r) - (w))
+
+
+/*++
+
+Name:
+	GetRingBufferAvailBytes()
+
+Description:
+	Get number of bytes available to read and to write to
+	for the specified ring buffer
+
+--*/
+static inline void
+GetRingBufferAvailBytes(RING_BUFFER_INFO *rbi, u32 *read, u32 *write)
+{
+	u32 read_loc,write_loc;
+
+	/* Capture the read/write indices before they changed */
+	read_loc = rbi->RingBuffer->ReadIndex;
+	write_loc = rbi->RingBuffer->WriteIndex;
+
+	*write = BYTES_AVAIL_TO_WRITE(read_loc, write_loc, rbi->RingDataSize);
+	*read = rbi->RingDataSize - *write;
+}
+
+/*++
+
+Name:
+	GetNextWriteLocation()
+
+Description:
+	Get the next write location for the specified ring buffer
+
+--*/
+static inline u32
+GetNextWriteLocation(RING_BUFFER_INFO* RingInfo)
+{
+	u32 next = RingInfo->RingBuffer->WriteIndex;
+
+	ASSERT(next < RingInfo->RingDataSize);
+
+	return next;
+}
+
+/*++
+
+Name:
+	SetNextWriteLocation()
+
+Description:
+	Set the next write location for the specified ring buffer
+
+--*/
+static inline void
+SetNextWriteLocation(RING_BUFFER_INFO* RingInfo, u32 NextWriteLocation)
+{
+	RingInfo->RingBuffer->WriteIndex = NextWriteLocation;
+}
+
+/*++
+
+Name:
+	GetNextReadLocation()
+
+Description:
+	Get the next read location for the specified ring buffer
+
+--*/
+static inline u32
+GetNextReadLocation(RING_BUFFER_INFO* RingInfo)
+{
+	u32 next = RingInfo->RingBuffer->ReadIndex;
+
+	ASSERT(next < RingInfo->RingDataSize);
+
+	return next;
+}
+
+/*++
+
+Name:
+	GetNextReadLocationWithOffset()
+
+Description:
+	Get the next read location + offset for the specified ring buffer.
+	This allows the caller to skip
+
+--*/
+static inline u32
+GetNextReadLocationWithOffset(RING_BUFFER_INFO* RingInfo, u32 Offset)
+{
+	u32 next = RingInfo->RingBuffer->ReadIndex;
+
+	ASSERT(next < RingInfo->RingDataSize);
+	next += Offset;
+	next %= RingInfo->RingDataSize;
+
+	return next;
+}
+
+/*++
+
+Name:
+	SetNextReadLocation()
+
+Description:
+	Set the next read location for the specified ring buffer
+
+--*/
+static inline void
+SetNextReadLocation(RING_BUFFER_INFO* RingInfo, u32 NextReadLocation)
+{
+	RingInfo->RingBuffer->ReadIndex = NextReadLocation;
+}
+
+
+/*++
+
+Name:
+	GetRingBuffer()
+
+Description:
+	Get the start of the ring buffer
+
+--*/
+static inline void *
+GetRingBuffer(RING_BUFFER_INFO* RingInfo)
+{
+	return (void *)RingInfo->RingBuffer->Buffer;
+}
+
+
+/*++
+
+Name:
+	GetRingBufferSize()
+
+Description:
+	Get the size of the ring buffer
+
+--*/
+static inline u32
+GetRingBufferSize(RING_BUFFER_INFO* RingInfo)
+{
+	return RingInfo->RingDataSize;
+}
+
+/*++
+
+Name:
+	GetRingBufferIndices()
+
+Description:
+	Get the read and write indices as u64 of the specified ring buffer
+
+--*/
+static inline u64
+GetRingBufferIndices(RING_BUFFER_INFO* RingInfo)
+{
+	return ((u64)RingInfo->RingBuffer->WriteIndex << 32) || RingInfo->RingBuffer->ReadIndex;
+}
+
+
+/*++
+
+Name:
+	DumpRingInfo()
+
+Description:
+	Dump out to console the ring buffer info
+
+--*/
+void DumpRingInfo(RING_BUFFER_INFO *RingInfo, char *Prefix)
+{
+	u32 bytesAvailToWrite;
+	u32 bytesAvailToRead;
+
+	GetRingBufferAvailBytes(RingInfo, &bytesAvailToRead, &bytesAvailToWrite);
+
+	DPRINT(VMBUS, DEBUG_RING_LVL, "%s <<ringinfo %p buffer %p avail write %u avail read %u read idx %u write idx %u>>",
+		Prefix,
+		RingInfo,
+		RingInfo->RingBuffer->Buffer,
+		bytesAvailToWrite,
+		bytesAvailToRead,
+		RingInfo->RingBuffer->ReadIndex,
+		RingInfo->RingBuffer->WriteIndex);
+}
+
+
+/* Internal routines */
+
+static u32
+CopyToRingBuffer(
+	RING_BUFFER_INFO	*RingInfo,
+	u32				StartWriteOffset,
+	void *				Src,
+	u32				SrcLen);
+
+static u32
+CopyFromRingBuffer(
+	RING_BUFFER_INFO	*RingInfo,
+	void *				Dest,
+	u32				DestLen,
+	u32				StartReadOffset);
+
+
+
+/*++
+
+Name:
+	RingBufferGetDebugInfo()
+
+Description:
+	Get various debug metrics for the specified ring buffer
+
+--*/
+void RingBufferGetDebugInfo(RING_BUFFER_INFO *RingInfo,
+			    RING_BUFFER_DEBUG_INFO *DebugInfo)
+{
+	u32 bytesAvailToWrite;
+	u32 bytesAvailToRead;
+
+	if (RingInfo->RingBuffer)
+	{
+		GetRingBufferAvailBytes(RingInfo, &bytesAvailToRead, &bytesAvailToWrite);
+
+		DebugInfo->BytesAvailToRead = bytesAvailToRead;
+		DebugInfo->BytesAvailToWrite = bytesAvailToWrite;
+		DebugInfo->CurrentReadIndex = RingInfo->RingBuffer->ReadIndex;
+		DebugInfo->CurrentWriteIndex = RingInfo->RingBuffer->WriteIndex;
+
+		DebugInfo->CurrentInterruptMask = RingInfo->RingBuffer->InterruptMask;
+	}
+}
+
+
+/*++
+
+Name:
+	GetRingBufferInterruptMask()
+
+Description:
+	Get the interrupt mask for the specified ring buffer
+
+--*/
+u32 GetRingBufferInterruptMask(RING_BUFFER_INFO *rbi)
+{
+	return rbi->RingBuffer->InterruptMask;
+}
+
+/*++
+
+Name:
+	RingBufferInit()
+
+Description:
+	Initialize the ring buffer
+
+--*/
+int RingBufferInit(RING_BUFFER_INFO *RingInfo, void *Buffer, u32 BufferLen)
+{
+	ASSERT(sizeof(RING_BUFFER) == PAGE_SIZE);
+
+	memset(RingInfo, 0, sizeof(RING_BUFFER_INFO));
+
+	RingInfo->RingBuffer = (RING_BUFFER*)Buffer;
+	RingInfo->RingBuffer->ReadIndex = RingInfo->RingBuffer->WriteIndex = 0;
+
+	RingInfo->RingSize = BufferLen;
+	RingInfo->RingDataSize = BufferLen - sizeof(RING_BUFFER);
+
+	spin_lock_init(&RingInfo->ring_lock);
+
+	return 0;
+}
+
+/*++
+
+Name:
+	RingBufferCleanup()
+
+Description:
+	Cleanup the ring buffer
+
+--*/
+void RingBufferCleanup(RING_BUFFER_INFO* RingInfo)
+{
+}
+
+/*++
+
+Name:
+	RingBufferWrite()
+
+Description:
+	Write to the ring buffer
+
+--*/
+int RingBufferWrite(RING_BUFFER_INFO *OutRingInfo,
+		    struct scatterlist *sglist, u32 sgcount)
+{
+	int i=0;
+	u32 byteAvailToWrite;
+	u32 byteAvailToRead;
+	u32 totalBytesToWrite=0;
+
+	struct scatterlist *sg;
+	volatile u32 nextWriteLocation;
+	u64 prevIndices=0;
+	unsigned long flags;
+
+	DPRINT_ENTER(VMBUS);
+
+	for_each_sg(sglist, sg, sgcount, i)
+	{
+		totalBytesToWrite += sg->length;
+	}
+
+	totalBytesToWrite += sizeof(u64);
+
+	spin_lock_irqsave(&OutRingInfo->ring_lock, flags);
+
+	GetRingBufferAvailBytes(OutRingInfo, &byteAvailToRead, &byteAvailToWrite);
+
+	DPRINT_DBG(VMBUS, "Writing %u bytes...", totalBytesToWrite);
+
+	/* DumpRingInfo(OutRingInfo, "BEFORE "); */
+
+	/* If there is only room for the packet, assume it is full. Otherwise, the next time around, we think the ring buffer */
+	/* is empty since the read index == write index */
+	if (byteAvailToWrite <= totalBytesToWrite)
+	{
+		DPRINT_DBG(VMBUS, "No more space left on outbound ring buffer (needed %u, avail %u)", totalBytesToWrite, byteAvailToWrite);
+
+		spin_unlock_irqrestore(&OutRingInfo->ring_lock, flags);
+
+		DPRINT_EXIT(VMBUS);
+
+		return -1;
+	}
+
+	/* Write to the ring buffer */
+	nextWriteLocation = GetNextWriteLocation(OutRingInfo);
+
+	for_each_sg(sglist, sg, sgcount, i)
+	{
+		nextWriteLocation = CopyToRingBuffer(OutRingInfo,
+						     nextWriteLocation,
+						     sg_virt(sg),
+						     sg->length);
+	}
+
+	/* Set previous packet start */
+	prevIndices = GetRingBufferIndices(OutRingInfo);
+
+	nextWriteLocation = CopyToRingBuffer(OutRingInfo,
+					     nextWriteLocation,
+					     &prevIndices,
+					     sizeof(u64));
+
+	/* Make sure we flush all writes before updating the writeIndex */
+	mb();
+
+	/* Now, update the write location */
+	SetNextWriteLocation(OutRingInfo, nextWriteLocation);
+
+	/* DumpRingInfo(OutRingInfo, "AFTER "); */
+
+	spin_unlock_irqrestore(&OutRingInfo->ring_lock, flags);
+
+	DPRINT_EXIT(VMBUS);
+
+	return 0;
+}
+
+
+/*++
+
+Name:
+	RingBufferPeek()
+
+Description:
+	Read without advancing the read index
+
+--*/
+int RingBufferPeek(RING_BUFFER_INFO *InRingInfo, void *Buffer, u32 BufferLen)
+{
+	u32 bytesAvailToWrite;
+	u32 bytesAvailToRead;
+	u32 nextReadLocation=0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&InRingInfo->ring_lock, flags);
+
+	GetRingBufferAvailBytes(InRingInfo, &bytesAvailToRead, &bytesAvailToWrite);
+
+	/* Make sure there is something to read */
+	if (bytesAvailToRead < BufferLen )
+	{
+		/* DPRINT_DBG(VMBUS, "got callback but not enough to read <avail to read %d read size %d>!!", bytesAvailToRead, BufferLen); */
+
+		spin_unlock_irqrestore(&InRingInfo->ring_lock, flags);
+
+		return -1;
+	}
+
+	/* Convert to byte offset */
+	nextReadLocation = GetNextReadLocation(InRingInfo);
+
+	nextReadLocation = CopyFromRingBuffer(InRingInfo,
+											Buffer,
+											BufferLen,
+											nextReadLocation);
+
+	spin_unlock_irqrestore(&InRingInfo->ring_lock, flags);
+
+	return 0;
+}
+
+
+/*++
+
+Name:
+	RingBufferRead()
+
+Description:
+	Read and advance the read index
+
+--*/
+int RingBufferRead(RING_BUFFER_INFO *InRingInfo, void *Buffer,
+		   u32 BufferLen, u32 Offset)
+{
+	u32 bytesAvailToWrite;
+	u32 bytesAvailToRead;
+	u32 nextReadLocation=0;
+	u64 prevIndices=0;
+	unsigned long flags;
+
+	ASSERT(BufferLen > 0);
+
+	spin_lock_irqsave(&InRingInfo->ring_lock, flags);
+
+	GetRingBufferAvailBytes(InRingInfo, &bytesAvailToRead, &bytesAvailToWrite);
+
+	DPRINT_DBG(VMBUS, "Reading %u bytes...", BufferLen);
+
+	/* DumpRingInfo(InRingInfo, "BEFORE "); */
+
+	/* Make sure there is something to read */
+	if (bytesAvailToRead < BufferLen )
+	{
+		DPRINT_DBG(VMBUS, "got callback but not enough to read <avail to read %d read size %d>!!", bytesAvailToRead, BufferLen);
+
+		spin_unlock_irqrestore(&InRingInfo->ring_lock, flags);
+
+		return -1;
+	}
+
+	nextReadLocation = GetNextReadLocationWithOffset(InRingInfo, Offset);
+
+	nextReadLocation = CopyFromRingBuffer(InRingInfo,
+											Buffer,
+											BufferLen,
+											nextReadLocation);
+
+	nextReadLocation = CopyFromRingBuffer(InRingInfo,
+											&prevIndices,
+											sizeof(u64),
+											nextReadLocation);
+
+	/* Make sure all reads are done before we update the read index since */
+	/* the writer may start writing to the read area once the read index is updated */
+	mb();
+
+	/* Update the read index */
+	SetNextReadLocation(InRingInfo, nextReadLocation);
+
+	/* DumpRingInfo(InRingInfo, "AFTER "); */
+
+	spin_unlock_irqrestore(&InRingInfo->ring_lock, flags);
+
+	return 0;
+}
+
+
+/*++
+
+Name:
+	CopyToRingBuffer()
+
+Description:
+	Helper routine to copy from source to ring buffer.
+	Assume there is enough room. Handles wrap-around in dest case only!!
+
+--*/
+static u32
+CopyToRingBuffer(
+	RING_BUFFER_INFO	*RingInfo,
+	u32				StartWriteOffset,
+	void *				Src,
+	u32				SrcLen)
+{
+	void * ringBuffer=GetRingBuffer(RingInfo);
+	u32 ringBufferSize=GetRingBufferSize(RingInfo);
+	u32 fragLen;
+
+	if (SrcLen > ringBufferSize - StartWriteOffset) /* wrap-around detected! */
+	{
+		DPRINT_DBG(VMBUS, "wrap-around detected!");
+
+		fragLen = ringBufferSize - StartWriteOffset;
+		memcpy(ringBuffer + StartWriteOffset, Src, fragLen);
+		memcpy(ringBuffer, Src + fragLen, SrcLen - fragLen);
+	}
+	else
+	{
+		memcpy(ringBuffer + StartWriteOffset, Src, SrcLen);
+	}
+
+	StartWriteOffset += SrcLen;
+	StartWriteOffset %= ringBufferSize;
+
+	return StartWriteOffset;
+}
+
+
+/*++
+
+Name:
+	CopyFromRingBuffer()
+
+Description:
+	Helper routine to copy to source from ring buffer.
+	Assume there is enough room. Handles wrap-around in src case only!!
+
+--*/
+static u32
+CopyFromRingBuffer(
+	RING_BUFFER_INFO	*RingInfo,
+	void *				Dest,
+	u32				DestLen,
+	u32				StartReadOffset)
+{
+	void * ringBuffer=GetRingBuffer(RingInfo);
+	u32 ringBufferSize=GetRingBufferSize(RingInfo);
+
+	u32 fragLen;
+
+	if (DestLen > ringBufferSize - StartReadOffset) /* wrap-around detected at the src */
+	{
+		DPRINT_DBG(VMBUS, "src wrap-around detected!");
+
+		fragLen = ringBufferSize - StartReadOffset;
+
+		memcpy(Dest, ringBuffer + StartReadOffset, fragLen);
+		memcpy(Dest + fragLen, ringBuffer, DestLen - fragLen);
+	}
+	else
+	{
+		memcpy(Dest, ringBuffer + StartReadOffset, DestLen);
+	}
+
+	StartReadOffset += DestLen;
+	StartReadOffset %= ringBufferSize;
+
+	return StartReadOffset;
+}
+
+
+/* eof */