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