drivers/staging/hv/ring_buffer.h

   1 /*
   2  *
   3  * Copyright (c) 2009, Microsoft Corporation.
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms and conditions of the GNU General Public License,
   7  * version 2, as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
  16  * Place - Suite 330, Boston, MA 02111-1307 USA.
  17  *
  18  * Authors:
  19  *   Haiyang Zhang <haiyangz@microsoft.com>
  20  *   Hank Janssen  <hjanssen@microsoft.com>
  21  *
  22  */
  23
  24
  25 #ifndef _RING_BUFFER_H_
  26 #define _RING_BUFFER_H_
  27
  28 #include <linux/scatterlist.h>
  29
  30 typedef struct _RING_BUFFER {
  31         /* Offset in bytes from the start of ring data below */
  32         volatile u32 WriteIndex;
  33
  34         /* Offset in bytes from the start of ring data below */
  35         volatile u32 ReadIndex;
  36
  37         volatile u32 InterruptMask;
  38
  39         /* Pad it to PAGE_SIZE so that data starts on page boundary */
  40         u8      Reserved[4084];
  41
  42         /* NOTE:
  43          * The InterruptMask field is used only for channels but since our
  44          * vmbus connection also uses this data structure and its data starts
  45          * here, we commented out this field.
  46          */
  47         /* volatile u32 InterruptMask; */
  48
  49         /*
  50          * Ring data starts here + RingDataStartOffset
  51          * !!! DO NOT place any fields below this !!!
  52          */
  53         u8 Buffer[0];
  54 } __attribute__((packed)) RING_BUFFER;
  55
  56 typedef struct _RING_BUFFER_INFO {
  57         RING_BUFFER *RingBuffer;
  58         u32 RingSize;                   /* Include the shared header */
  59         spinlock_t ring_lock;
  60
  61         u32 RingDataSize;               /* < ringSize */
  62         u32 RingDataStartOffset;
  63
  64 } RING_BUFFER_INFO;
  65
  66 typedef struct _RING_BUFFER_DEBUG_INFO {
  67         u32 CurrentInterruptMask;
  68         u32 CurrentReadIndex;
  69         u32 CurrentWriteIndex;
  70         u32 BytesAvailToRead;
  71         u32 BytesAvailToWrite;
  72 } RING_BUFFER_DEBUG_INFO;
  73
  74
  75
  76 /* Interface */
  77
  78
  79 int RingBufferInit(RING_BUFFER_INFO *RingInfo, void *Buffer, u32 BufferLen);
  80
  81 void RingBufferCleanup(RING_BUFFER_INFO *RingInfo);
  82
  83 int RingBufferWrite(RING_BUFFER_INFO *RingInfo,
  84                     struct scatterlist *sglist,
  85                     u32 sgcount);
  86
  87 int RingBufferPeek(RING_BUFFER_INFO *RingInfo, void *Buffer, u32 BufferLen);
  88
  89 int RingBufferRead(RING_BUFFER_INFO *RingInfo,
  90                    void *Buffer,
  91                    u32 BufferLen,
  92                    u32 Offset);
  93
  94 u32 GetRingBufferInterruptMask(RING_BUFFER_INFO *RingInfo);
  95
  96 void DumpRingInfo(RING_BUFFER_INFO *RingInfo, char *Prefix);
  97
  98 void RingBufferGetDebugInfo(RING_BUFFER_INFO *RingInfo,
  99                             RING_BUFFER_DEBUG_INFO *DebugInfo);
 100
 101 #endif /* _RING_BUFFER_H_ */