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       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                 :          0 : 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                 :          0 :         const struct cq_desc *desc = desc_arg;
      58                 :          0 :         const u8 type_color = desc->type_color;
      59                 :            : 
      60                 :          0 :         *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                 :          0 :         rmb();
      70                 :            : 
      71                 :          0 :         *type = type_color & CQ_DESC_TYPE_MASK;
      72                 :          0 :         *q_number = le16_to_cpu(desc->q_number) & CQ_DESC_Q_NUM_MASK;
      73         [ #  # ]:          0 :         *completed_index = le16_to_cpu(desc->completed_index) &
      74                 :            :                 CQ_DESC_COMP_NDX_MASK;
      75                 :          0 : }
      76                 :            : 
      77                 :            : #endif /* _CQ_DESC_H_ */