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,
80 		 struct ib_udata *udata,
81 		 bool is_req,
82 		 struct ib_ucontext *context,
83 		 struct rxe_queue_buf *buf,
84 		 size_t buf_size,
85 		 struct rxe_mmap_info **ip_p);
86 
87 void rxe_queue_reset(struct rxe_queue *q);
88 
89 struct rxe_queue *rxe_queue_init(struct rxe_dev *rxe,
90 				 int *num_elem,
91 				 unsigned int elem_size);
92 
93 int rxe_queue_resize(struct rxe_queue *q,
94 		     unsigned int *num_elem_p,
95 		     unsigned int elem_size,
96 		     struct ib_ucontext *context,
97 		     struct ib_udata *udata,
98 		     /* Protect producers while resizing queue */
99 		     spinlock_t *producer_lock,
100 		     /* Protect consumers while resizing queue */
101 		     spinlock_t *consumer_lock);
102 
103 void rxe_queue_cleanup(struct rxe_queue *queue);
104 
105 static inline int next_index(struct rxe_queue *q, int index)
106 {
107 	return (index + 1) & q->buf->index_mask;
108 }
109 
110 static inline int queue_empty(struct rxe_queue *q)
111 {
112 	return ((q->buf->producer_index - q->buf->consumer_index)
113 			& q->index_mask) == 0;
114 }
115 
116 static inline int queue_full(struct rxe_queue *q)
117 {
118 	return ((q->buf->producer_index + 1 - q->buf->consumer_index)
119 			& q->index_mask) == 0;
120 }
121 
122 static inline void advance_producer(struct rxe_queue *q)
123 {
124 	q->buf->producer_index = (q->buf->producer_index + 1)
125 			& q->index_mask;
126 }
127 
128 static inline void advance_consumer(struct rxe_queue *q)
129 {
130 	q->buf->consumer_index = (q->buf->consumer_index + 1)
131 			& q->index_mask;
132 }
133 
134 static inline void *producer_addr(struct rxe_queue *q)
135 {
136 	return q->buf->data + ((q->buf->producer_index & q->index_mask)
137 				<< q->log2_elem_size);
138 }
139 
140 static inline void *consumer_addr(struct rxe_queue *q)
141 {
142 	return q->buf->data + ((q->buf->consumer_index & q->index_mask)
143 				<< q->log2_elem_size);
144 }
145 
146 static inline unsigned int producer_index(struct rxe_queue *q)
147 {
148 	return q->buf->producer_index;
149 }
150 
151 static inline unsigned int consumer_index(struct rxe_queue *q)
152 {
153 	return q->buf->consumer_index;
154 }
155 
156 static inline void *addr_from_index(struct rxe_queue *q, unsigned int index)
157 {
158 	return q->buf->data + ((index & q->index_mask)
159 				<< q->buf->log2_elem_size);
160 }
161 
162 static inline unsigned int index_from_addr(const struct rxe_queue *q,
163 					   const void *addr)
164 {
165 	return (((u8 *)addr - q->buf->data) >> q->log2_elem_size)
166 		& q->index_mask;
167 }
168 
169 static inline unsigned int queue_count(const struct rxe_queue *q)
170 {
171 	return (q->buf->producer_index - q->buf->consumer_index)
172 		& q->index_mask;
173 }
174 
175 static inline void *queue_head(struct rxe_queue *q)
176 {
177 	return queue_empty(q) ? NULL : consumer_addr(q);
178 }
179 
180 #endif /* RXE_QUEUE_H */
181