diff options
Diffstat (limited to 'drivers/infiniband/hw/vmw_pvrdma/pvrdma_ring.h')
| -rw-r--r-- | drivers/infiniband/hw/vmw_pvrdma/pvrdma_ring.h | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/drivers/infiniband/hw/vmw_pvrdma/pvrdma_ring.h b/drivers/infiniband/hw/vmw_pvrdma/pvrdma_ring.h new file mode 100644 index 000000000..8b558ae23 --- /dev/null +++ b/drivers/infiniband/hw/vmw_pvrdma/pvrdma_ring.h @@ -0,0 +1,114 @@ +/* + * Copyright (c) 2012-2016 VMware, Inc. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of EITHER the GNU General Public License + * version 2 as published by the Free Software Foundation or the BSD + * 2-Clause License. This program is distributed in the hope that it + * will be useful, but WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED + * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + * See the GNU General Public License version 2 for more details at + * http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html. + * + * You should have received a copy of the GNU General Public License + * along with this program available in the file COPYING in the main + * directory of this source tree. + * + * The BSD 2-Clause License + * + * Redistribution and use in source and binary forms, with or + * without modification, are permitted provided that the following + * conditions are met: + * + * - Redistributions of source code must retain the above + * copyright notice, this list of conditions and the following + * disclaimer. + * + * - Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials + * provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, + * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR + * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#ifndef __PVRDMA_RING_H__ +#define __PVRDMA_RING_H__ + +#include <linux/types.h> + +#define PVRDMA_INVALID_IDX -1 /* Invalid index. */ + +struct pvrdma_ring { + atomic_t prod_tail; /* Producer tail. */ + atomic_t cons_head; /* Consumer head. */ +}; + +struct pvrdma_ring_state { + struct pvrdma_ring tx; /* Tx ring. */ + struct pvrdma_ring rx; /* Rx ring. */ +}; + +static inline int pvrdma_idx_valid(__u32 idx, __u32 max_elems) +{ + /* Generates fewer instructions than a less-than. */ + return (idx & ~((max_elems << 1) - 1)) == 0; +} + +static inline __s32 pvrdma_idx(atomic_t *var, __u32 max_elems) +{ + const unsigned int idx = atomic_read(var); + + if (pvrdma_idx_valid(idx, max_elems)) + return idx & (max_elems - 1); + return PVRDMA_INVALID_IDX; +} + +static inline void pvrdma_idx_ring_inc(atomic_t *var, __u32 max_elems) +{ + __u32 idx = atomic_read(var) + 1; /* Increment. */ + + idx &= (max_elems << 1) - 1; /* Modulo size, flip gen. */ + atomic_set(var, idx); +} + +static inline __s32 pvrdma_idx_ring_has_space(const struct pvrdma_ring *r, + __u32 max_elems, __u32 *out_tail) +{ + const __u32 tail = atomic_read(&r->prod_tail); + const __u32 head = atomic_read(&r->cons_head); + + if (pvrdma_idx_valid(tail, max_elems) && + pvrdma_idx_valid(head, max_elems)) { + *out_tail = tail & (max_elems - 1); + return tail != (head ^ max_elems); + } + return PVRDMA_INVALID_IDX; +} + +static inline __s32 pvrdma_idx_ring_has_data(const struct pvrdma_ring *r, + __u32 max_elems, __u32 *out_head) +{ + const __u32 tail = atomic_read(&r->prod_tail); + const __u32 head = atomic_read(&r->cons_head); + + if (pvrdma_idx_valid(tail, max_elems) && + pvrdma_idx_valid(head, max_elems)) { + *out_head = head & (max_elems - 1); + return tail != head; + } + return PVRDMA_INVALID_IDX; +} + +#endif /* __PVRDMA_RING_H__ */ |