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
cq_desc_dec(const struct cq_desc * desc_arg,u8 * type,u8 * color,u16 * q_number,u16 * completed_index)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
