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* 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 <>
* Hank Janssen <>
#ifndef _RING_BUFFER_H_
#define _RING_BUFFER_H_
#include <linux/scatterlist.h>
typedef struct _RING_BUFFER {
/* Offset in bytes from the start of ring data below */
volatile u32 WriteIndex;
/* Offset in bytes from the start of ring data below */
volatile u32 ReadIndex;
volatile u32 InterruptMask;
/* Pad it to PAGE_SIZE so that data starts on page boundary */
u8 Reserved[4084];
/* NOTE:
* The InterruptMask field is used only for channels but since our
* vmbus connection also uses this data structure and its data starts
* here, we commented out this field.
/* volatile u32 InterruptMask; */
* Ring data starts here + RingDataStartOffset
* !!! DO NOT place any fields below this !!!
u8 Buffer[0];
} __attribute__((packed)) RING_BUFFER;
typedef struct _RING_BUFFER_INFO {
RING_BUFFER *RingBuffer;
u32 RingSize; /* Include the shared header */
spinlock_t ring_lock;
u32 RingDataSize; /* < ringSize */
u32 RingDataStartOffset;
typedef struct _RING_BUFFER_DEBUG_INFO {
u32 CurrentInterruptMask;
u32 CurrentReadIndex;
u32 CurrentWriteIndex;
u32 BytesAvailToRead;
u32 BytesAvailToWrite;
/* Interface */
int RingBufferInit(RING_BUFFER_INFO *RingInfo, void *Buffer, u32 BufferLen);
void RingBufferCleanup(RING_BUFFER_INFO *RingInfo);
int RingBufferWrite(RING_BUFFER_INFO *RingInfo,
struct scatterlist *sglist,
u32 sgcount);
int RingBufferPeek(RING_BUFFER_INFO *RingInfo, void *Buffer, u32 BufferLen);
int RingBufferRead(RING_BUFFER_INFO *RingInfo,
void *Buffer,
u32 BufferLen,
u32 Offset);
u32 GetRingBufferInterruptMask(RING_BUFFER_INFO *RingInfo);
void DumpRingInfo(RING_BUFFER_INFO *RingInfo, char *Prefix);
void RingBufferGetDebugInfo(RING_BUFFER_INFO *RingInfo,
#endif /* _RING_BUFFER_H_ */