1 /* 2 * Copyright 2014 Cisco Systems, Inc. All rights reserved. 3 * 4 * This program is free software; you may redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; version 2 of the License. 7 * 8 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 9 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 10 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 11 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 12 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 13 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 14 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 15 * SOFTWARE. 16 */ 17 18 #ifndef _CQ_DESC_H_ 19 #define _CQ_DESC_H_ 20 21 /* 22 * Completion queue descriptor types 23 */ 24 enum cq_desc_types { 25 CQ_DESC_TYPE_WQ_ENET = 0, 26 CQ_DESC_TYPE_DESC_COPY = 1, 27 CQ_DESC_TYPE_WQ_EXCH = 2, 28 CQ_DESC_TYPE_RQ_ENET = 3, 29 CQ_DESC_TYPE_RQ_FCP = 4, 30 }; 31 32 /* Completion queue descriptor: 16B 33 * 34 * All completion queues have this basic layout. The 35 * type_specific area is unique for each completion 36 * queue type. 37 */ 38 struct cq_desc { 39 __le16 completed_index; 40 __le16 q_number; 41 u8 type_specific[11]; 42 u8 type_color; 43 }; 44 45 #define CQ_DESC_TYPE_BITS 4 46 #define CQ_DESC_TYPE_MASK ((1 << CQ_DESC_TYPE_BITS) - 1) 47 #define CQ_DESC_COLOR_MASK 1 48 #define CQ_DESC_COLOR_SHIFT 7 49 #define CQ_DESC_Q_NUM_BITS 10 50 #define CQ_DESC_Q_NUM_MASK ((1 << CQ_DESC_Q_NUM_BITS) - 1) 51 #define CQ_DESC_COMP_NDX_BITS 12 52 #define CQ_DESC_COMP_NDX_MASK ((1 << CQ_DESC_COMP_NDX_BITS) - 1) 53 54 static inline void cq_desc_dec(const struct cq_desc *desc_arg, 55 u8 *type, u8 *color, u16 *q_number, u16 *completed_index) 56 { 57 const struct cq_desc *desc = desc_arg; 58 const u8 type_color = desc->type_color; 59 60 *color = (type_color >> CQ_DESC_COLOR_SHIFT) & CQ_DESC_COLOR_MASK; 61 62 /* 63 * Make sure color bit is read from desc *before* other fields 64 * are read from desc. Hardware guarantees color bit is last 65 * bit (byte) written. Adding the rmb() prevents the compiler 66 * and/or CPU from reordering the reads which would potentially 67 * result in reading stale values. 68 */ 69 rmb(); 70 71 *type = type_color & CQ_DESC_TYPE_MASK; 72 *q_number = le16_to_cpu(desc->q_number) & CQ_DESC_Q_NUM_MASK; 73 *completed_index = le16_to_cpu(desc->completed_index) & 74 CQ_DESC_COMP_NDX_MASK; 75 } 76 77 #endif /* _CQ_DESC_H_ */ 78