IB/mlx5: Mmap the HCA's core clock register to user-space

In order to read the HCA's current cycles register, we need
to map it to user-space. Add support to map this register
via mmap command.

Signed-off-by: Matan Barak <matanb@mellanox.com>
Reviewed-by: Moshe Lazer <moshel@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index b2a6643..1303487 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -65,7 +65,9 @@
 
 enum mlx5_ib_mmap_cmd {
 	MLX5_IB_MMAP_REGULAR_PAGE		= 0,
-	MLX5_IB_MMAP_GET_CONTIGUOUS_PAGES	= 1, /* always last */
+	MLX5_IB_MMAP_GET_CONTIGUOUS_PAGES	= 1,
+	/* 5 is chosen in order to be compatible with old versions of libmlx5 */
+	MLX5_IB_MMAP_CORE_CLOCK			= 5,
 };
 
 enum {