1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
2 | /* |
3 | * Copyright 2008 Cisco Systems, Inc. All rights reserved. |
4 | * Copyright 2007 Nuova Systems, Inc. All rights reserved. |
5 | */ |
6 | #ifndef _CQ_DESC_H_ |
7 | #define _CQ_DESC_H_ |
8 | |
9 | /* |
10 | * Completion queue descriptor types |
11 | */ |
12 | enum cq_desc_types { |
13 | CQ_DESC_TYPE_WQ_ENET = 0, |
14 | CQ_DESC_TYPE_DESC_COPY = 1, |
15 | CQ_DESC_TYPE_WQ_EXCH = 2, |
16 | CQ_DESC_TYPE_RQ_ENET = 3, |
17 | CQ_DESC_TYPE_RQ_FCP = 4, |
18 | }; |
19 | |
20 | /* Completion queue descriptor: 16B |
21 | * |
22 | * All completion queues have this basic layout. The |
23 | * type_specfic area is unique for each completion |
24 | * queue type. |
25 | */ |
26 | struct cq_desc { |
27 | __le16 completed_index; |
28 | __le16 q_number; |
29 | u8 type_specfic[11]; |
30 | u8 type_color; |
31 | }; |
32 | |
33 | #define CQ_DESC_TYPE_BITS 4 |
34 | #define CQ_DESC_TYPE_MASK ((1 << CQ_DESC_TYPE_BITS) - 1) |
35 | #define CQ_DESC_COLOR_MASK 1 |
36 | #define CQ_DESC_COLOR_SHIFT 7 |
37 | #define CQ_DESC_Q_NUM_BITS 10 |
38 | #define CQ_DESC_Q_NUM_MASK ((1 << CQ_DESC_Q_NUM_BITS) - 1) |
39 | #define CQ_DESC_COMP_NDX_BITS 12 |
40 | #define CQ_DESC_COMP_NDX_MASK ((1 << CQ_DESC_COMP_NDX_BITS) - 1) |
41 | |
42 | static inline void cq_desc_dec(const struct cq_desc *desc_arg, |
43 | u8 *type, u8 *color, u16 *q_number, u16 *completed_index) |
44 | { |
45 | const struct cq_desc *desc = desc_arg; |
46 | const u8 type_color = desc->type_color; |
47 | |
48 | *color = (type_color >> CQ_DESC_COLOR_SHIFT) & CQ_DESC_COLOR_MASK; |
49 | |
50 | /* |
51 | * Make sure color bit is read from desc *before* other fields |
52 | * are read from desc. Hardware guarantees color bit is last |
53 | * bit (byte) written. Adding the rmb() prevents the compiler |
54 | * and/or CPU from reordering the reads which would potentially |
55 | * result in reading stale values. |
56 | */ |
57 | |
58 | rmb(); |
59 | |
60 | *type = type_color & CQ_DESC_TYPE_MASK; |
61 | *q_number = le16_to_cpu(desc->q_number) & CQ_DESC_Q_NUM_MASK; |
62 | *completed_index = le16_to_cpu(desc->completed_index) & |
63 | CQ_DESC_COMP_NDX_MASK; |
64 | } |
65 | |
66 | #endif /* _CQ_DESC_H_ */ |
67 | |