scif_rb.h
4.03 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
/*
* Intel MIC Platform Software Stack (MPSS)
*
* This file is provided under a dual BSD/GPLv2 license. When using or
* redistributing this file, you may do so under either license.
*
* GPL LICENSE SUMMARY
*
* Copyright(c) 2014 Intel Corporation.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that 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.
*
* BSD LICENSE
*
* Copyright(c) 2014 Intel Corporation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Intel Corporation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* Intel SCIF driver.
*/
#ifndef SCIF_RB_H
#define SCIF_RB_H
/*
* This file describes a general purpose, byte based ring buffer. Writers to the
* ring buffer need to synchronize using a lock. The same is true for readers,
* although in practice, the ring buffer has a single reader. It is lockless
* between producer and consumer so it can handle being used across the PCIe
* bus. The ring buffer ensures that there are no reads across the PCIe bus for
* performance reasons. Two of these are used to form a single bidirectional
* queue-pair across PCIe.
*/
/*
* struct scif_rb - SCIF Ring Buffer
*
* @rb_base: The base of the memory used for storing RB messages
* @read_ptr: Pointer to the read offset
* @write_ptr: Pointer to the write offset
* @size: Size of the memory in rb_base
* @current_read_offset: Cached read offset for performance
* @current_write_offset: Cached write offset for performance
*/
struct scif_rb {
void *rb_base;
u32 *read_ptr;
u32 *write_ptr;
u32 size;
u32 current_read_offset;
u32 current_write_offset;
};
/* methods used by both */
void scif_rb_init(struct scif_rb *rb, u32 *read_ptr, u32 *write_ptr,
void *rb_base, u8 size);
/* writer only methods */
/* write a new command, then scif_rb_commit() */
int scif_rb_write(struct scif_rb *rb, void *msg, u32 size);
/* after write(), then scif_rb_commit() */
void scif_rb_commit(struct scif_rb *rb);
/* query space available for writing to a RB. */
u32 scif_rb_space(struct scif_rb *rb);
/* reader only methods */
/* read a new message from the ring buffer of size bytes */
u32 scif_rb_get_next(struct scif_rb *rb, void *msg, u32 size);
/* update the read pointer so that the space can be reused */
void scif_rb_update_read_ptr(struct scif_rb *rb);
/* count the number of bytes that can be read */
u32 scif_rb_count(struct scif_rb *rb, u32 size);
#endif