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114 lines
3.9 KiB
114 lines
3.9 KiB
/* |
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* Copyright (c) 2012-2016 VMware, Inc. All rights reserved. |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of EITHER the GNU General Public License |
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* version 2 as published by the Free Software Foundation or the BSD |
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* 2-Clause License. This program is distributed in the hope that it |
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* will be useful, but WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED |
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* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. |
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* See the GNU General Public License version 2 for more details at |
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* http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program available in the file COPYING in the main |
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* directory of this source tree. |
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* |
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* The BSD 2-Clause License |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials |
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* provided with the distribution. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, |
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR |
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED |
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* OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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#ifndef __PVRDMA_RING_H__ |
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#define __PVRDMA_RING_H__ |
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#include <linux/types.h> |
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#define PVRDMA_INVALID_IDX -1 /* Invalid index. */ |
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struct pvrdma_ring { |
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atomic_t prod_tail; /* Producer tail. */ |
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atomic_t cons_head; /* Consumer head. */ |
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}; |
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struct pvrdma_ring_state { |
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struct pvrdma_ring tx; /* Tx ring. */ |
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struct pvrdma_ring rx; /* Rx ring. */ |
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}; |
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static inline int pvrdma_idx_valid(__u32 idx, __u32 max_elems) |
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{ |
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/* Generates fewer instructions than a less-than. */ |
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return (idx & ~((max_elems << 1) - 1)) == 0; |
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} |
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static inline __s32 pvrdma_idx(atomic_t *var, __u32 max_elems) |
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{ |
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const unsigned int idx = atomic_read(var); |
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if (pvrdma_idx_valid(idx, max_elems)) |
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return idx & (max_elems - 1); |
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return PVRDMA_INVALID_IDX; |
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} |
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static inline void pvrdma_idx_ring_inc(atomic_t *var, __u32 max_elems) |
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{ |
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__u32 idx = atomic_read(var) + 1; /* Increment. */ |
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idx &= (max_elems << 1) - 1; /* Modulo size, flip gen. */ |
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atomic_set(var, idx); |
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} |
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static inline __s32 pvrdma_idx_ring_has_space(const struct pvrdma_ring *r, |
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__u32 max_elems, __u32 *out_tail) |
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{ |
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const __u32 tail = atomic_read(&r->prod_tail); |
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const __u32 head = atomic_read(&r->cons_head); |
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if (pvrdma_idx_valid(tail, max_elems) && |
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pvrdma_idx_valid(head, max_elems)) { |
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*out_tail = tail & (max_elems - 1); |
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return tail != (head ^ max_elems); |
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} |
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return PVRDMA_INVALID_IDX; |
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} |
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static inline __s32 pvrdma_idx_ring_has_data(const struct pvrdma_ring *r, |
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__u32 max_elems, __u32 *out_head) |
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{ |
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const __u32 tail = atomic_read(&r->prod_tail); |
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const __u32 head = atomic_read(&r->cons_head); |
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if (pvrdma_idx_valid(tail, max_elems) && |
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pvrdma_idx_valid(head, max_elems)) { |
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*out_head = head & (max_elems - 1); |
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return tail != head; |
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} |
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return PVRDMA_INVALID_IDX; |
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} |
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#endif /* __PVRDMA_RING_H__ */
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