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 struct hv_ring_buffer {
  31         /* Offset in bytes from the start of ring data below */
  32         volatile u32 write_index;
  33
  34         /* Offset in bytes from the start of ring data below */
  35         volatile u32 read_index;
  36
  37         volatile u32 interrupt_mask;
  38
  39         /* Pad it to PAGE_SIZE so that data starts on page boundary */
  40         u8      reserved[4084];
  41
  42         /* NOTE:
  43          * The interrupt_mask 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));
  55
  56 struct hv_ring_buffer_info {
  57         struct hv_ring_buffer *ring_buffer;
  58         u32 ring_size;                  /* Include the shared header */
  59         spinlock_t ring_lock;
  60
  61         u32 ring_datasize;              /* < ring_size */
  62         u32 ring_data_startoffset;
  63 };
  64
  65 struct hv_ring_buffer_debug_info {
  66         u32 current_interrupt_mask;
  67         u32 current_read_index;
  68         u32 current_write_index;
  69         u32 bytes_avail_toread;
  70         u32 bytes_avail_towrite;
  71 };
  72
  73
  74
  75 /* Interface */
  76
  77
  78 int ringbuffer_init(struct hv_ring_buffer_info *ring_info, void *buffer,
  79                    u32 buflen);
  80
  81 void ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info);
  82
  83 int ringbuffer_write(struct hv_ring_buffer_info *ring_info,
  84                     struct scatterlist *sglist,
  85                     u32 sgcount);
  86
  87 int ringbuffer_peek(struct hv_ring_buffer_info *ring_info, void *buffer,
  88                    u32 buflen);
  89
  90 int ringbuffer_read(struct hv_ring_buffer_info *ring_info,
  91                    void *buffer,
  92                    u32 buflen,
  93                    u32 offset);
  94
  95 u32 get_ringbuffer_interrupt_mask(struct hv_ring_buffer_info *ring_info);
  96
  97 void dump_ring_info(struct hv_ring_buffer_info *ring_info, char *prefix);
  98
  99 void ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
 100                             struct hv_ring_buffer_debug_info *debug_info);
 101
 102 #endif /* _RING_BUFFER_H_ */