1 /*
2 * Copyright 2008-2010 Cisco Systems, Inc. All rights reserved.
3 * Copyright 2007 Nuova Systems, Inc. All rights reserved.
4 *
5 * This program is free software; you may redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; version 2 of the License.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
10 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
11 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
12 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
13 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
14 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
15 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
16 * SOFTWARE.
17 *
18 */
19
20 #ifndef _CQ_DESC_H_
21 #define _CQ_DESC_H_
22
23 /*
24 * Completion queue descriptor types
25 */
26 enum cq_desc_types {
27 CQ_DESC_TYPE_WQ_ENET = 0,
28 CQ_DESC_TYPE_DESC_COPY = 1,
29 CQ_DESC_TYPE_WQ_EXCH = 2,
30 CQ_DESC_TYPE_RQ_ENET = 3,
31 CQ_DESC_TYPE_RQ_FCP = 4,
32 };
33
34 /* Completion queue descriptor: 16B
35 *
36 * All completion queues have this basic layout. The
37 * type_specfic area is unique for each completion
38 * queue type.
39 */
40 struct cq_desc {
41 __le16 completed_index;
42 __le16 q_number;
43 u8 type_specfic[11];
44 u8 type_color;
45 };
46
47 #define CQ_DESC_TYPE_BITS 4
48 #define CQ_DESC_TYPE_MASK ((1 << CQ_DESC_TYPE_BITS) - 1)
49 #define CQ_DESC_COLOR_MASK 1
50 #define CQ_DESC_COLOR_SHIFT 7
51 #define CQ_DESC_Q_NUM_BITS 10
52 #define CQ_DESC_Q_NUM_MASK ((1 << CQ_DESC_Q_NUM_BITS) - 1)
53 #define CQ_DESC_COMP_NDX_BITS 12
54 #define CQ_DESC_COMP_NDX_MASK ((1 << CQ_DESC_COMP_NDX_BITS) - 1)
55
56 static inline void cq_desc_dec(const struct cq_desc *desc_arg,
57 u8 *type, u8 *color, u16 *q_number, u16 *completed_index)
58 {
59 const struct cq_desc *desc = desc_arg;
60 const u8 type_color = desc->type_color;
61
62 *color = (type_color >> CQ_DESC_COLOR_SHIFT) & CQ_DESC_COLOR_MASK;
63
64 /*
65 * Make sure color bit is read from desc *before* other fields
66 * are read from desc. Hardware guarantees color bit is last
67 * bit (byte) written. Adding the rmb() prevents the compiler
68 * and/or CPU from reordering the reads which would potentially
69 * result in reading stale values.
70 */
71
72 rmb();
73
74 *type = type_color & CQ_DESC_TYPE_MASK;
75 *q_number = le16_to_cpu(desc->q_number) & CQ_DESC_Q_NUM_MASK;
76 *completed_index = le16_to_cpu(desc->completed_index) &
77 CQ_DESC_COMP_NDX_MASK;
78 }
79
80 #endif /* _CQ_DESC_H_ */