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 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