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/*
* Copyright(c) 2016 Intel Corporation.
*
* This file is provided under a dual BSD/GPLv2 license. When using or
* redistributing this file, you may do so under either license.
*
* GPL LICENSE SUMMARY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* 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 for more details.
*
* BSD 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.
* - Neither the name of Intel Corporation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* 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
* OWNER 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.
*
*/
#include <rdma/rdma_vt.h>
#include <rdma/ib_hdrs.h>
/*
* Convert the AETH credit code into the number of credits.
*/
static const u16 credit_table[31] = {
0, /* 0 */
1, /* 1 */
2, /* 2 */
3, /* 3 */
4, /* 4 */
6, /* 5 */
8, /* 6 */
12, /* 7 */
16, /* 8 */
24, /* 9 */
32, /* A */
48, /* B */
64, /* C */
96, /* D */
128, /* E */
192, /* F */
256, /* 10 */
384, /* 11 */
512, /* 12 */
768, /* 13 */
1024, /* 14 */
1536, /* 15 */
2048, /* 16 */
3072, /* 17 */
4096, /* 18 */
6144, /* 19 */
8192, /* 1A */
12288, /* 1B */
16384, /* 1C */
24576, /* 1D */
32768 /* 1E */
};
/**
* rvt_compute_aeth - compute the AETH (syndrome + MSN)
* @qp: the queue pair to compute the AETH for
*
* Returns the AETH.
*/
__be32 rvt_compute_aeth(struct rvt_qp *qp)
{
u32 aeth = qp->r_msn & IB_MSN_MASK;
if (qp->ibqp.srq) {
/*
* Shared receive queues don't generate credits.
* Set the credit field to the invalid value.
*/
aeth |= IB_AETH_CREDIT_INVAL << IB_AETH_CREDIT_SHIFT;
} else {
u32 min, max, x;
u32 credits;
struct rvt_rwq *wq = qp->r_rq.wq;
u32 head;
u32 tail;
/* sanity check pointers before trusting them */
head = wq->head;
if (head >= qp->r_rq.size)
head = 0;
tail = wq->tail;
if (tail >= qp->r_rq.size)
tail = 0;
/*
* Compute the number of credits available (RWQEs).
* There is a small chance that the pair of reads are
* not atomic, which is OK, since the fuzziness is
* resolved as further ACKs go out.
*/
credits = head - tail;
if ((int)credits < 0)
credits += qp->r_rq.size;
/*
* Binary search the credit table to find the code to
* use.
*/
min = 0;
max = 31;
for (;;) {
x = (min + max) / 2;
if (credit_table[x] == credits)
break;
if (credit_table[x] > credits) {
max = x;
} else {
if (min == x)
break;
min = x;
}
}
aeth |= x << IB_AETH_CREDIT_SHIFT;
}
return cpu_to_be32(aeth);
}
EXPORT_SYMBOL(rvt_compute_aeth);
/**
* rvt_get_credit - flush the send work queue of a QP
* @qp: the qp who's send work queue to flush
* @aeth: the Acknowledge Extended Transport Header
*
* The QP s_lock should be held.
*/
void rvt_get_credit(struct rvt_qp *qp, u32 aeth)
{
struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
u32 credit = (aeth >> IB_AETH_CREDIT_SHIFT) & IB_AETH_CREDIT_MASK;
lockdep_assert_held(&qp->s_lock);
/*
* If the credit is invalid, we can send
* as many packets as we like. Otherwise, we have to
* honor the credit field.
*/
if (credit == IB_AETH_CREDIT_INVAL) {
if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT)) {
qp->s_flags |= RVT_S_UNLIMITED_CREDIT;
if (qp->s_flags & RVT_S_WAIT_SSN_CREDIT) {
qp->s_flags &= ~RVT_S_WAIT_SSN_CREDIT;
rdi->driver_f.schedule_send(qp);
}
}
} else if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT)) {
/* Compute new LSN (i.e., MSN + credit) */
credit = (aeth + credit_table[credit]) & IB_MSN_MASK;
if (rvt_cmp_msn(credit, qp->s_lsn) > 0) {
qp->s_lsn = credit;
if (qp->s_flags & RVT_S_WAIT_SSN_CREDIT) {
qp->s_flags &= ~RVT_S_WAIT_SSN_CREDIT;
rdi->driver_f.schedule_send(qp);
}
}
}
}
EXPORT_SYMBOL(rvt_get_credit);
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