1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
2 | /* |
3 | * Copyright 2008-2010 Cisco Systems, Inc. All rights reserved. |
4 | * Copyright 2007 Nuova Systems, Inc. All rights reserved. |
5 | */ |
6 | |
7 | #ifndef _CQ_DESC_H_ |
8 | #define _CQ_DESC_H_ |
9 | |
10 | /* |
11 | * Completion queue descriptor types |
12 | */ |
13 | enum cq_desc_types { |
14 | CQ_DESC_TYPE_WQ_ENET = 0, |
15 | CQ_DESC_TYPE_DESC_COPY = 1, |
16 | CQ_DESC_TYPE_WQ_EXCH = 2, |
17 | CQ_DESC_TYPE_RQ_ENET = 3, |
18 | CQ_DESC_TYPE_RQ_FCP = 4, |
19 | }; |
20 | |
21 | /* Completion queue descriptor: 16B |
22 | * |
23 | * All completion queues have this basic layout. The |
24 | * type_specfic area is unique for each completion |
25 | * queue type. |
26 | */ |
27 | struct cq_desc { |
28 | __le16 completed_index; |
29 | __le16 q_number; |
30 | u8 type_specfic[11]; |
31 | u8 type_color; |
32 | }; |
33 | |
34 | #define CQ_DESC_TYPE_BITS 4 |
35 | #define CQ_DESC_TYPE_MASK ((1 << CQ_DESC_TYPE_BITS) - 1) |
36 | #define CQ_DESC_COLOR_MASK 1 |
37 | #define CQ_DESC_COLOR_SHIFT 7 |
38 | #define CQ_DESC_Q_NUM_BITS 10 |
39 | #define CQ_DESC_Q_NUM_MASK ((1 << CQ_DESC_Q_NUM_BITS) - 1) |
40 | #define CQ_DESC_COMP_NDX_BITS 12 |
41 | #define CQ_DESC_COMP_NDX_MASK ((1 << CQ_DESC_COMP_NDX_BITS) - 1) |
42 | |
43 | static inline void cq_desc_dec(const struct cq_desc *desc_arg, |
44 | u8 *type, u8 *color, u16 *q_number, u16 *completed_index) |
45 | { |
46 | const struct cq_desc *desc = desc_arg; |
47 | const u8 type_color = desc->type_color; |
48 | |
49 | *color = (type_color >> CQ_DESC_COLOR_SHIFT) & CQ_DESC_COLOR_MASK; |
50 | |
51 | /* |
52 | * Make sure color bit is read from desc *before* other fields |
53 | * are read from desc. Hardware guarantees color bit is last |
54 | * bit (byte) written. Adding the rmb() prevents the compiler |
55 | * and/or CPU from reordering the reads which would potentially |
56 | * result in reading stale values. |
57 | */ |
58 | |
59 | rmb(); |
60 | |
61 | *type = type_color & CQ_DESC_TYPE_MASK; |
62 | *q_number = le16_to_cpu(desc->q_number) & CQ_DESC_Q_NUM_MASK; |
63 | *completed_index = le16_to_cpu(desc->completed_index) & |
64 | CQ_DESC_COMP_NDX_MASK; |
65 | } |
66 | |
67 | #endif /* _CQ_DESC_H_ */ |
68 | |