1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
2 | /* Copyright 2014 Cisco Systems, Inc. All rights reserved. */ |
3 | |
4 | #ifndef _CQ_DESC_H_ |
5 | #define _CQ_DESC_H_ |
6 | |
7 | /* |
8 | * Completion queue descriptor types |
9 | */ |
10 | enum cq_desc_types { |
11 | CQ_DESC_TYPE_WQ_ENET = 0, |
12 | CQ_DESC_TYPE_DESC_COPY = 1, |
13 | CQ_DESC_TYPE_WQ_EXCH = 2, |
14 | CQ_DESC_TYPE_RQ_ENET = 3, |
15 | CQ_DESC_TYPE_RQ_FCP = 4, |
16 | }; |
17 | |
18 | /* Completion queue descriptor: 16B |
19 | * |
20 | * All completion queues have this basic layout. The |
21 | * type_specific area is unique for each completion |
22 | * queue type. |
23 | */ |
24 | struct cq_desc { |
25 | __le16 completed_index; |
26 | __le16 q_number; |
27 | u8 type_specific[11]; |
28 | u8 type_color; |
29 | }; |
30 | |
31 | #define CQ_DESC_TYPE_BITS 4 |
32 | #define CQ_DESC_TYPE_MASK ((1 << CQ_DESC_TYPE_BITS) - 1) |
33 | #define CQ_DESC_COLOR_MASK 1 |
34 | #define CQ_DESC_COLOR_SHIFT 7 |
35 | #define CQ_DESC_Q_NUM_BITS 10 |
36 | #define CQ_DESC_Q_NUM_MASK ((1 << CQ_DESC_Q_NUM_BITS) - 1) |
37 | #define CQ_DESC_COMP_NDX_BITS 12 |
38 | #define CQ_DESC_COMP_NDX_MASK ((1 << CQ_DESC_COMP_NDX_BITS) - 1) |
39 | |
40 | static inline void cq_desc_dec(const struct cq_desc *desc_arg, |
41 | u8 *type, u8 *color, u16 *q_number, u16 *completed_index) |
42 | { |
43 | const struct cq_desc *desc = desc_arg; |
44 | const u8 type_color = desc->type_color; |
45 | |
46 | *color = (type_color >> CQ_DESC_COLOR_SHIFT) & CQ_DESC_COLOR_MASK; |
47 | |
48 | /* |
49 | * Make sure color bit is read from desc *before* other fields |
50 | * are read from desc. Hardware guarantees color bit is last |
51 | * bit (byte) written. Adding the rmb() prevents the compiler |
52 | * and/or CPU from reordering the reads which would potentially |
53 | * result in reading stale values. |
54 | */ |
55 | rmb(); |
56 | |
57 | *type = type_color & CQ_DESC_TYPE_MASK; |
58 | *q_number = le16_to_cpu(desc->q_number) & CQ_DESC_Q_NUM_MASK; |
59 | *completed_index = le16_to_cpu(desc->completed_index) & |
60 | CQ_DESC_COMP_NDX_MASK; |
61 | } |
62 | |
63 | #endif /* _CQ_DESC_H_ */ |
64 | |