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1/*2 * Copyright (c) 2012-2016 VMware, Inc. All rights reserved.3 *4 * This program is free software; you can redistribute it and/or5 * modify it under the terms of EITHER the GNU General Public License6 * version 2 as published by the Free Software Foundation or the BSD7 * 2-Clause License. This program is distributed in the hope that it8 * will be useful, but WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED9 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.10 * See the GNU General Public License version 2 for more details at11 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html.12 *13 * You should have received a copy of the GNU General Public License14 * along with this program available in the file COPYING in the main15 * directory of this source tree.16 *17 * The BSD 2-Clause License18 *19 * Redistribution and use in source and binary forms, with or20 * without modification, are permitted provided that the following21 * conditions are met:22 *23 * - Redistributions of source code must retain the above24 * copyright notice, this list of conditions and the following25 * disclaimer.26 *27 * - Redistributions in binary form must reproduce the above28 * copyright notice, this list of conditions and the following29 * disclaimer in the documentation and/or other materials30 * provided with the distribution.31 *32 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS33 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT34 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS35 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE36 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,37 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES38 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR39 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)40 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,41 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)42 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED43 * OF THE POSSIBILITY OF SUCH DAMAGE.44 */45 46#ifndef __PVRDMA_RING_H__47#define __PVRDMA_RING_H__48 49#include <linux/types.h>50 51#define PVRDMA_INVALID_IDX -1 /* Invalid index. */52 53struct pvrdma_ring {54 atomic_t prod_tail; /* Producer tail. */55 atomic_t cons_head; /* Consumer head. */56};57 58struct pvrdma_ring_state {59 struct pvrdma_ring tx; /* Tx ring. */60 struct pvrdma_ring rx; /* Rx ring. */61};62 63static inline int pvrdma_idx_valid(__u32 idx, __u32 max_elems)64{65 /* Generates fewer instructions than a less-than. */66 return (idx & ~((max_elems << 1) - 1)) == 0;67}68 69static inline __s32 pvrdma_idx(atomic_t *var, __u32 max_elems)70{71 const unsigned int idx = atomic_read(var);72 73 if (pvrdma_idx_valid(idx, max_elems))74 return idx & (max_elems - 1);75 return PVRDMA_INVALID_IDX;76}77 78static inline void pvrdma_idx_ring_inc(atomic_t *var, __u32 max_elems)79{80 __u32 idx = atomic_read(var) + 1; /* Increment. */81 82 idx &= (max_elems << 1) - 1; /* Modulo size, flip gen. */83 atomic_set(var, idx);84}85 86static inline __s32 pvrdma_idx_ring_has_space(const struct pvrdma_ring *r,87 __u32 max_elems, __u32 *out_tail)88{89 const __u32 tail = atomic_read(&r->prod_tail);90 const __u32 head = atomic_read(&r->cons_head);91 92 if (pvrdma_idx_valid(tail, max_elems) &&93 pvrdma_idx_valid(head, max_elems)) {94 *out_tail = tail & (max_elems - 1);95 return tail != (head ^ max_elems);96 }97 return PVRDMA_INVALID_IDX;98}99 100static inline __s32 pvrdma_idx_ring_has_data(const struct pvrdma_ring *r,101 __u32 max_elems, __u32 *out_head)102{103 const __u32 tail = atomic_read(&r->prod_tail);104 const __u32 head = atomic_read(&r->cons_head);105 106 if (pvrdma_idx_valid(tail, max_elems) &&107 pvrdma_idx_valid(head, max_elems)) {108 *out_head = head & (max_elems - 1);109 return tail != head;110 }111 return PVRDMA_INVALID_IDX;112}113 114#endif /* __PVRDMA_RING_H__ */115