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
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
/*
* Copyright (c) 2012-2016 VMware, Inc. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of EITHER the GNU General Public License
* version 2 as published by the Free Software Foundation or the BSD
* 2-Clause License. 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 version 2 for more details at
* http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html.
*
* You should have received a copy of the GNU General Public License
* along with this program available in the file COPYING in the main
* directory of this source tree.
*
* The BSD 2-Clause License
*
* 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.
*
* 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 HOLDER 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.
*/
#ifndef __PVRDMA_RING_H__
#define __PVRDMA_RING_H__
#include <linux/types.h>
#define PVRDMA_INVALID_IDX -1 /* Invalid index. */
struct pvrdma_ring {
atomic_t prod_tail; /* Producer tail. */
atomic_t cons_head; /* Consumer head. */
};
struct pvrdma_ring_state {
struct pvrdma_ring tx; /* Tx ring. */
struct pvrdma_ring rx; /* Rx ring. */
};
static inline int pvrdma_idx_valid(__u32 idx, __u32 max_elems)
{
/* Generates fewer instructions than a less-than. */
return (idx & ~((max_elems << 1) - 1)) == 0;
}
static inline __s32 pvrdma_idx(atomic_t *var, __u32 max_elems)
{
const unsigned int idx = atomic_read(var);
if (pvrdma_idx_valid(idx, max_elems))
return idx & (max_elems - 1);
return PVRDMA_INVALID_IDX;
}
static inline void pvrdma_idx_ring_inc(atomic_t *var, __u32 max_elems)
{
__u32 idx = atomic_read(var) + 1; /* Increment. */
idx &= (max_elems << 1) - 1; /* Modulo size, flip gen. */
atomic_set(var, idx);
}
static inline __s32 pvrdma_idx_ring_has_space(const struct pvrdma_ring *r,
__u32 max_elems, __u32 *out_tail)
{
const __u32 tail = atomic_read(&r->prod_tail);
const __u32 head = atomic_read(&r->cons_head);
if (pvrdma_idx_valid(tail, max_elems) &&
pvrdma_idx_valid(head, max_elems)) {
*out_tail = tail & (max_elems - 1);
return tail != (head ^ max_elems);
}
return PVRDMA_INVALID_IDX;
}
static inline __s32 pvrdma_idx_ring_has_data(const struct pvrdma_ring *r,
__u32 max_elems, __u32 *out_head)
{
const __u32 tail = atomic_read(&r->prod_tail);
const __u32 head = atomic_read(&r->cons_head);
if (pvrdma_idx_valid(tail, max_elems) &&
pvrdma_idx_valid(head, max_elems)) {
*out_head = head & (max_elems - 1);
return tail != head;
}
return PVRDMA_INVALID_IDX;
}
static inline bool pvrdma_idx_ring_is_valid_idx(const struct pvrdma_ring *r,
__u32 max_elems, __u32 *idx)
{
const __u32 tail = atomic_read(&r->prod_tail);
const __u32 head = atomic_read(&r->cons_head);
if (pvrdma_idx_valid(tail, max_elems) &&
pvrdma_idx_valid(head, max_elems) &&
pvrdma_idx_valid(*idx, max_elems)) {
if (tail > head && (*idx < tail && *idx >= head))
return true;
else if (head > tail && (*idx >= head || *idx < tail))
return true;
}
return false;
}
#endif /* __PVRDMA_RING_H__ */
|
