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