1 /*
2  * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
3  * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
4  *
5  * This software is available to you under a choice of one of two
6  * licenses.  You may choose to be licensed under the terms of the GNU
7  * General Public License (GPL) Version 2, available from the file
8  * COPYING in the main directory of this source tree, or the
9  * OpenIB.org BSD license below:
10  *
11  *     Redistribution and use in source and binary forms, with or
12  *     without modification, are permitted provided that the following
13  *     conditions are met:
14  *
15  *	- Redistributions of source code must retain the above
16  *	  copyright notice, this list of conditions and the following
17  *	  disclaimer.
18  *
19  *	- Redistributions in binary form must reproduce the above
20  *	  copyright notice, this list of conditions and the following
21  *	  disclaimer in the documentation and/or other materials
22  *	  provided with the distribution.
23  *
24  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
28  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
29  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
30  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
31  * SOFTWARE.
32  */
33 
34 #ifndef RXE_QUEUE_H
35 #define RXE_QUEUE_H
36 
37 /* implements a simple circular buffer that can optionally be
38  * shared between user space and the kernel and can be resized
39 
40  * the requested element size is rounded up to a power of 2
41  * and the number of elements in the buffer is also rounded
42  * up to a power of 2. Since the queue is empty when the
43  * producer and consumer indices match the maximum capacity
44  * of the queue is one less than the number of element slots
45  */
46 
47 /* this data structure is shared between user space and kernel
48  * space for those cases where the queue is shared. It contains
49  * the producer and consumer indices. Is also contains a copy
50  * of the queue size parameters for user space to use but the
51  * kernel must use the parameters in the rxe_queue struct
52  * this MUST MATCH the corresponding librxe struct
53  * for performance reasons arrange to have producer and consumer
54  * pointers in separate cache lines
55  * the kernel should always mask the indices to avoid accessing
56  * memory outside of the data area
57  */
58 struct rxe_queue_buf {
59 	__u32			log2_elem_size;
60 	__u32			index_mask;
61 	__u32			pad_1[30];
62 	__u32			producer_index;
63 	__u32			pad_2[31];
64 	__u32			consumer_index;
65 	__u32			pad_3[31];
66 	__u8			data[0];
67 };
68 
69 struct rxe_queue {
70 	struct rxe_dev		*rxe;
71 	struct rxe_queue_buf	*buf;
72 	struct rxe_mmap_info	*ip;
73 	size_t			buf_size;
74 	size_t			elem_size;
75 	unsigned int		log2_elem_size;
76 	unsigned int		index_mask;
77 };
78 
79 int do_mmap_info(struct rxe_dev *rxe, struct mminfo __user *outbuf,
80 		 struct ib_udata *udata, struct rxe_queue_buf *buf,
81 		 size_t buf_size, struct rxe_mmap_info **ip_p);
82 
83 void rxe_queue_reset(struct rxe_queue *q);
84 
85 struct rxe_queue *rxe_queue_init(struct rxe_dev *rxe,
86 				 int *num_elem,
87 				 unsigned int elem_size);
88 
89 int rxe_queue_resize(struct rxe_queue *q, unsigned int *num_elem_p,
90 		     unsigned int elem_size, struct ib_udata *udata,
91 		     struct mminfo __user *outbuf,
92 		     /* Protect producers while resizing queue */
93 		     spinlock_t *producer_lock,
94 		     /* Protect consumers while resizing queue */
95 		     spinlock_t *consumer_lock);
96 
97 void rxe_queue_cleanup(struct rxe_queue *queue);
98 
99 static inline int next_index(struct rxe_queue *q, int index)
100 {
101 	return (index + 1) & q->buf->index_mask;
102 }
103 
104 static inline int queue_empty(struct rxe_queue *q)
105 {
106 	return ((q->buf->producer_index - q->buf->consumer_index)
107 			& q->index_mask) == 0;
108 }
109 
110 static inline int queue_full(struct rxe_queue *q)
111 {
112 	return ((q->buf->producer_index + 1 - q->buf->consumer_index)
113 			& q->index_mask) == 0;
114 }
115 
116 static inline void advance_producer(struct rxe_queue *q)
117 {
118 	q->buf->producer_index = (q->buf->producer_index + 1)
119 			& q->index_mask;
120 }
121 
122 static inline void advance_consumer(struct rxe_queue *q)
123 {
124 	q->buf->consumer_index = (q->buf->consumer_index + 1)
125 			& q->index_mask;
126 }
127 
128 static inline void *producer_addr(struct rxe_queue *q)
129 {
130 	return q->buf->data + ((q->buf->producer_index & q->index_mask)
131 				<< q->log2_elem_size);
132 }
133 
134 static inline void *consumer_addr(struct rxe_queue *q)
135 {
136 	return q->buf->data + ((q->buf->consumer_index & q->index_mask)
137 				<< q->log2_elem_size);
138 }
139 
140 static inline unsigned int producer_index(struct rxe_queue *q)
141 {
142 	return q->buf->producer_index;
143 }
144 
145 static inline unsigned int consumer_index(struct rxe_queue *q)
146 {
147 	return q->buf->consumer_index;
148 }
149 
150 static inline void *addr_from_index(struct rxe_queue *q, unsigned int index)
151 {
152 	return q->buf->data + ((index & q->index_mask)
153 				<< q->buf->log2_elem_size);
154 }
155 
156 static inline unsigned int index_from_addr(const struct rxe_queue *q,
157 					   const void *addr)
158 {
159 	return (((u8 *)addr - q->buf->data) >> q->log2_elem_size)
160 		& q->index_mask;
161 }
162 
163 static inline unsigned int queue_count(const struct rxe_queue *q)
164 {
165 	return (q->buf->producer_index - q->buf->consumer_index)
166 		& q->index_mask;
167 }
168 
169 static inline void *queue_head(struct rxe_queue *q)
170 {
171 	return queue_empty(q) ? NULL : consumer_addr(q);
172 }
173 
174 #endif /* RXE_QUEUE_H */
175