1/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
2/*
3 * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
4 * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
5 */
6
7#ifndef RXE_QUEUE_H
8#define RXE_QUEUE_H
9
10/* implements a simple circular buffer that can optionally be
11 * shared between user space and the kernel and can be resized
12
13 * the requested element size is rounded up to a power of 2
14 * and the number of elements in the buffer is also rounded
15 * up to a power of 2. Since the queue is empty when the
16 * producer and consumer indices match the maximum capacity
17 * of the queue is one less than the number of element slots
18 */
19
20/* this data structure is shared between user space and kernel
21 * space for those cases where the queue is shared. It contains
22 * the producer and consumer indices. Is also contains a copy
23 * of the queue size parameters for user space to use but the
24 * kernel must use the parameters in the rxe_queue struct
25 * this MUST MATCH the corresponding librxe struct
26 * for performance reasons arrange to have producer and consumer
27 * pointers in separate cache lines
28 * the kernel should always mask the indices to avoid accessing
29 * memory outside of the data area
30 */
31struct rxe_queue_buf {
32	__u32			log2_elem_size;
33	__u32			index_mask;
34	__u32			pad_1[30];
35	__u32			producer_index;
36	__u32			pad_2[31];
37	__u32			consumer_index;
38	__u32			pad_3[31];
39	__u8			data[];
40};
41
42struct rxe_queue {
43	struct rxe_dev		*rxe;
44	struct rxe_queue_buf	*buf;
45	struct rxe_mmap_info	*ip;
46	size_t			buf_size;
47	size_t			elem_size;
48	unsigned int		log2_elem_size;
49	unsigned int		index_mask;
50};
51
52int do_mmap_info(struct rxe_dev *rxe, struct mminfo __user *outbuf,
53		 struct ib_udata *udata, struct rxe_queue_buf *buf,
54		 size_t buf_size, struct rxe_mmap_info **ip_p);
55
56void rxe_queue_reset(struct rxe_queue *q);
57
58struct rxe_queue *rxe_queue_init(struct rxe_dev *rxe,
59				 int *num_elem,
60				 unsigned int elem_size);
61
62int rxe_queue_resize(struct rxe_queue *q, unsigned int *num_elem_p,
63		     unsigned int elem_size, struct ib_udata *udata,
64		     struct mminfo __user *outbuf,
65		     /* Protect producers while resizing queue */
66		     spinlock_t *producer_lock,
67		     /* Protect consumers while resizing queue */
68		     spinlock_t *consumer_lock);
69
70void rxe_queue_cleanup(struct rxe_queue *queue);
71
72static inline int next_index(struct rxe_queue *q, int index)
73{
74	return (index + 1) & q->buf->index_mask;
75}
76
77static inline int queue_empty(struct rxe_queue *q)
78{
79	return ((q->buf->producer_index - q->buf->consumer_index)
80			& q->index_mask) == 0;
81}
82
83static inline int queue_full(struct rxe_queue *q)
84{
85	return ((q->buf->producer_index + 1 - q->buf->consumer_index)
86			& q->index_mask) == 0;
87}
88
89static inline void advance_producer(struct rxe_queue *q)
90{
91	q->buf->producer_index = (q->buf->producer_index + 1)
92			& q->index_mask;
93}
94
95static inline void advance_consumer(struct rxe_queue *q)
96{
97	q->buf->consumer_index = (q->buf->consumer_index + 1)
98			& q->index_mask;
99}
100
101static inline void *producer_addr(struct rxe_queue *q)
102{
103	return q->buf->data + ((q->buf->producer_index & q->index_mask)
104				<< q->log2_elem_size);
105}
106
107static inline void *consumer_addr(struct rxe_queue *q)
108{
109	return q->buf->data + ((q->buf->consumer_index & q->index_mask)
110				<< q->log2_elem_size);
111}
112
113static inline unsigned int producer_index(struct rxe_queue *q)
114{
115	return q->buf->producer_index;
116}
117
118static inline unsigned int consumer_index(struct rxe_queue *q)
119{
120	return q->buf->consumer_index;
121}
122
123static inline void *addr_from_index(struct rxe_queue *q, unsigned int index)
124{
125	return q->buf->data + ((index & q->index_mask)
126				<< q->buf->log2_elem_size);
127}
128
129static inline unsigned int index_from_addr(const struct rxe_queue *q,
130					   const void *addr)
131{
132	return (((u8 *)addr - q->buf->data) >> q->log2_elem_size)
133		& q->index_mask;
134}
135
136static inline unsigned int queue_count(const struct rxe_queue *q)
137{
138	return (q->buf->producer_index - q->buf->consumer_index)
139		& q->index_mask;
140}
141
142static inline void *queue_head(struct rxe_queue *q)
143{
144	return queue_empty(q) ? NULL : consumer_addr(q);
145}
146
147#endif /* RXE_QUEUE_H */
148