include/linux/mlx5/doorbell.h

   1 /*
   2  * Copyright (c) 2013-2015, Mellanox Technologies. All rights reserved.
   3  *
   4  * This software is available to you under a choice of one of two
   5  * licenses.  You may choose to be licensed under the terms of the GNU
   6  * General Public License (GPL) Version 2, available from the file
   7  * COPYING in the main directory of this source tree, or the
   8  * OpenIB.org BSD license below:
   9  *
  10  *     Redistribution and use in source and binary forms, with or
  11  *     without modification, are permitted provided that the following
  12  *     conditions are met:
  13  *
  14  *      - Redistributions of source code must retain the above
  15  *        copyright notice, this list of conditions and the following
  16  *        disclaimer.
  17  *
  18  *      - Redistributions in binary form must reproduce the above
  19  *        copyright notice, this list of conditions and the following
  20  *        disclaimer in the documentation and/or other materials
  21  *        provided with the distribution.
  22  *
  23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30  * SOFTWARE.
  31  */
  32
  33 #ifndef MLX5_DOORBELL_H
  34 #define MLX5_DOORBELL_H
  35
  36 #define MLX5_BF_OFFSET        0x800
  37 #define MLX5_CQ_DOORBELL      0x20
  38
  39 #if BITS_PER_LONG == 64
  40 /* Assume that we can just write a 64-bit doorbell atomically.  s390
  41  * actually doesn't have writeq() but S/390 systems don't even have
  42  * PCI so we won't worry about it.
  43  */
  44
  45 #define MLX5_DECLARE_DOORBELL_LOCK(name)
  46 #define MLX5_INIT_DOORBELL_LOCK(ptr)    do { } while (0)
  47 #define MLX5_GET_DOORBELL_LOCK(ptr)      (NULL)
  48
  49 static inline void mlx5_write64(__be32 val[2], void __iomem *dest,
  50                                 spinlock_t *doorbell_lock)
  51 {
  52         __raw_writeq(*(u64 *)val, dest);
  53 }
  54
  55 #else
  56
  57 /* Just fall back to a spinlock to protect the doorbell if
  58  * BITS_PER_LONG is 32 -- there's no portable way to do atomic 64-bit
  59  * MMIO writes.
  60  */
  61
  62 #define MLX5_DECLARE_DOORBELL_LOCK(name) spinlock_t name;
  63 #define MLX5_INIT_DOORBELL_LOCK(ptr)     spin_lock_init(ptr)
  64 #define MLX5_GET_DOORBELL_LOCK(ptr)      (ptr)
  65
  66 static inline void mlx5_write64(__be32 val[2], void __iomem *dest,
  67                                 spinlock_t *doorbell_lock)
  68 {
  69         unsigned long flags;
  70
  71         if (doorbell_lock)
  72                 spin_lock_irqsave(doorbell_lock, flags);
  73         __raw_writel((__force u32) val[0], dest);
  74         __raw_writel((__force u32) val[1], dest + 4);
  75         if (doorbell_lock)
  76                 spin_unlock_irqrestore(doorbell_lock, flags);
  77 }
  78
  79 #endif
  80
  81 #endif /* MLX5_DOORBELL_H */