1/*
  2 * Intel MIC Platform Software Stack (MPSS)
  3 *
  4 * This file is provided under a dual BSD/GPLv2 license.  When using or
  5 * redistributing this file, you may do so under either license.
  6 *
  7 * GPL LICENSE SUMMARY
  8 *
  9 * Copyright(c) 2014 Intel Corporation.
 10 *
 11 * This program is free software; you can redistribute it and/or modify
 12 * it under the terms of version 2 of the GNU General Public License as
 13 * published by the Free Software Foundation.
 14 *
 15 * This program is distributed in the hope that it will be useful, but
 16 * WITHOUT ANY WARRANTY; without even the implied warranty of
 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 18 * General Public License for more details.
 19 *
 20 * BSD LICENSE
 21 *
 22 * Copyright(c) 2014 Intel Corporation.
 23 *
 24 * Redistribution and use in source and binary forms, with or without
 25 * modification, are permitted provided that the following conditions
 26 * are met:
 27 *
 28 * * Redistributions of source code must retain the above copyright
 29 *   notice, this list of conditions and the following disclaimer.
 30 * * Redistributions in binary form must reproduce the above copyright
 31 *   notice, this list of conditions and the following disclaimer in
 32 *   the documentation and/or other materials provided with the
 33 *   distribution.
 34 * * Neither the name of Intel Corporation nor the names of its
 35 *   contributors may be used to endorse or promote products derived
 36 *   from this software without specific prior written permission.
 37 *
 38 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 39 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 40 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 41 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 42 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 43 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 44 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 45 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 46 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 47 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 48 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 49 *
 50 * Intel SCIF driver.
 51 */
 52#ifndef SCIF_RB_H
 53#define SCIF_RB_H
 54/*
 55 * This file describes a general purpose, byte based ring buffer. Writers to the
 56 * ring buffer need to synchronize using a lock. The same is true for readers,
 57 * although in practice, the ring buffer has a single reader. It is lockless
 58 * between producer and consumer so it can handle being used across the PCIe
 59 * bus. The ring buffer ensures that there are no reads across the PCIe bus for
 60 * performance reasons. Two of these are used to form a single bidirectional
 61 * queue-pair across PCIe.
 62 */
 63/*
 64 * struct scif_rb - SCIF Ring Buffer
 65 *
 66 * @rb_base: The base of the memory used for storing RB messages
 67 * @read_ptr: Pointer to the read offset
 68 * @write_ptr: Pointer to the write offset
 69 * @size: Size of the memory in rb_base
 70 * @current_read_offset: Cached read offset for performance
 71 * @current_write_offset: Cached write offset for performance
 72 */
 73struct scif_rb {
 74	void *rb_base;
 75	u32 *read_ptr;
 76	u32 *write_ptr;
 77	u32 size;
 78	u32 current_read_offset;
 79	u32 current_write_offset;
 80};
 81
 82/* methods used by both */
 83void scif_rb_init(struct scif_rb *rb, u32 *read_ptr, u32 *write_ptr,
 84		  void *rb_base, u8 size);
 85/* writer only methods */
 86/* write a new command, then scif_rb_commit() */
 87int scif_rb_write(struct scif_rb *rb, void *msg, u32 size);
 88/* after write(), then scif_rb_commit() */
 89void scif_rb_commit(struct scif_rb *rb);
 90/* query space available for writing to a RB. */
 91u32 scif_rb_space(struct scif_rb *rb);
 92
 93/* reader only methods */
 94/* read a new message from the ring buffer of size bytes */
 95u32 scif_rb_get_next(struct scif_rb *rb, void *msg, u32 size);
 96/* update the read pointer so that the space can be reused */
 97void scif_rb_update_read_ptr(struct scif_rb *rb);
 98/* count the number of bytes that can be read */
 99u32 scif_rb_count(struct scif_rb *rb, u32 size);
100#endif