| /* |
| * 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); |
