1/*
2 * Copyright(c) 2016 Intel Corporation.
3 *
4 * This file is provided under a dual BSD/GPLv2 license.  When using or
5 * redistributing this file, you may do so under either license.
6 *
7 * GPL LICENSE SUMMARY
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of version 2 of the GNU General Public License as
11 * published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16 * General Public License for more details.
17 *
18 * BSD LICENSE
19 *
20 * Redistribution and use in source and binary forms, with or without
21 * modification, are permitted provided that the following conditions
22 * are met:
23 *
24 *  - Redistributions of source code must retain the above copyright
25 *    notice, this list of conditions and the following disclaimer.
26 *  - Redistributions in binary form must reproduce the above copyright
27 *    notice, this list of conditions and the following disclaimer in
28 *    the documentation and/or other materials provided with the
29 *    distribution.
30 *  - Neither the name of Intel Corporation nor the names of its
31 *    contributors may be used to endorse or promote products derived
32 *    from this software without specific prior written permission.
33 *
34 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
35 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
36 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
37 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
38 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
39 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
40 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
41 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
42 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
43 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
44 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
45 *
46 */
47
48#include <rdma/rdmavt_qp.h>
49#include <rdma/ib_hdrs.h>
50
51/*
52 * Convert the AETH credit code into the number of credits.
53 */
54static const u16 credit_table[31] = {
55	0,                      /* 0 */
56	1,                      /* 1 */
57	2,                      /* 2 */
58	3,                      /* 3 */
59	4,                      /* 4 */
60	6,                      /* 5 */
61	8,                      /* 6 */
62	12,                     /* 7 */
63	16,                     /* 8 */
64	24,                     /* 9 */
65	32,                     /* A */
66	48,                     /* B */
67	64,                     /* C */
68	96,                     /* D */
69	128,                    /* E */
70	192,                    /* F */
71	256,                    /* 10 */
72	384,                    /* 11 */
73	512,                    /* 12 */
74	768,                    /* 13 */
75	1024,                   /* 14 */
76	1536,                   /* 15 */
77	2048,                   /* 16 */
78	3072,                   /* 17 */
79	4096,                   /* 18 */
80	6144,                   /* 19 */
81	8192,                   /* 1A */
82	12288,                  /* 1B */
83	16384,                  /* 1C */
84	24576,                  /* 1D */
85	32768                   /* 1E */
86};
87
88/**
89 * rvt_compute_aeth - compute the AETH (syndrome + MSN)
90 * @qp: the queue pair to compute the AETH for
91 *
92 * Returns the AETH.
93 */
94__be32 rvt_compute_aeth(struct rvt_qp *qp)
95{
96	u32 aeth = qp->r_msn & IB_MSN_MASK;
97
98	if (qp->ibqp.srq) {
99		/*
100		 * Shared receive queues don't generate credits.
101		 * Set the credit field to the invalid value.
102		 */
103		aeth |= IB_AETH_CREDIT_INVAL << IB_AETH_CREDIT_SHIFT;
104	} else {
105		u32 min, max, x;
106		u32 credits;
107		u32 head;
108		u32 tail;
109
110		credits = READ_ONCE(qp->r_rq.kwq->count);
111		if (credits == 0) {
112			/* sanity check pointers before trusting them */
113			if (qp->ip) {
114				head = RDMA_READ_UAPI_ATOMIC(qp->r_rq.wq->head);
115				tail = RDMA_READ_UAPI_ATOMIC(qp->r_rq.wq->tail);
116			} else {
117				head = READ_ONCE(qp->r_rq.kwq->head);
118				tail = READ_ONCE(qp->r_rq.kwq->tail);
119			}
120			if (head >= qp->r_rq.size)
121				head = 0;
122			if (tail >= qp->r_rq.size)
123				tail = 0;
124			/*
125			 * Compute the number of credits available (RWQEs).
126			 * There is a small chance that the pair of reads are
127			 * not atomic, which is OK, since the fuzziness is
128			 * resolved as further ACKs go out.
129			 */
130			credits = rvt_get_rq_count(&qp->r_rq, head, tail);
131		}
132		/*
133		 * Binary search the credit table to find the code to
134		 * use.
135		 */
136		min = 0;
137		max = 31;
138		for (;;) {
139			x = (min + max) / 2;
140			if (credit_table[x] == credits)
141				break;
142			if (credit_table[x] > credits) {
143				max = x;
144			} else {
145				if (min == x)
146					break;
147				min = x;
148			}
149		}
150		aeth |= x << IB_AETH_CREDIT_SHIFT;
151	}
152	return cpu_to_be32(aeth);
153}
154EXPORT_SYMBOL(rvt_compute_aeth);
155
156/**
157 * rvt_get_credit - flush the send work queue of a QP
158 * @qp: the qp who's send work queue to flush
159 * @aeth: the Acknowledge Extended Transport Header
160 *
161 * The QP s_lock should be held.
162 */
163void rvt_get_credit(struct rvt_qp *qp, u32 aeth)
164{
165	struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
166	u32 credit = (aeth >> IB_AETH_CREDIT_SHIFT) & IB_AETH_CREDIT_MASK;
167
168	lockdep_assert_held(&qp->s_lock);
169	/*
170	 * If the credit is invalid, we can send
171	 * as many packets as we like.  Otherwise, we have to
172	 * honor the credit field.
173	 */
174	if (credit == IB_AETH_CREDIT_INVAL) {
175		if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT)) {
176			qp->s_flags |= RVT_S_UNLIMITED_CREDIT;
177			if (qp->s_flags & RVT_S_WAIT_SSN_CREDIT) {
178				qp->s_flags &= ~RVT_S_WAIT_SSN_CREDIT;
179				rdi->driver_f.schedule_send(qp);
180			}
181		}
182	} else if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT)) {
183		/* Compute new LSN (i.e., MSN + credit) */
184		credit = (aeth + credit_table[credit]) & IB_MSN_MASK;
185		if (rvt_cmp_msn(credit, qp->s_lsn) > 0) {
186			qp->s_lsn = credit;
187			if (qp->s_flags & RVT_S_WAIT_SSN_CREDIT) {
188				qp->s_flags &= ~RVT_S_WAIT_SSN_CREDIT;
189				rdi->driver_f.schedule_send(qp);
190			}
191		}
192	}
193}
194EXPORT_SYMBOL(rvt_get_credit);
195
196/**
197 * rvt_restart_sge - rewind the sge state for a wqe
198 * @ss: the sge state pointer
199 * @wqe: the wqe to rewind
200 * @len: the data length from the start of the wqe in bytes
201 *
202 * Returns the remaining data length.
203 */
204u32 rvt_restart_sge(struct rvt_sge_state *ss, struct rvt_swqe *wqe, u32 len)
205{
206	ss->sge = wqe->sg_list[0];
207	ss->sg_list = wqe->sg_list + 1;
208	ss->num_sge = wqe->wr.num_sge;
209	ss->total_len = wqe->length;
210	rvt_skip_sge(ss, len, false);
211	return wqe->length - len;
212}
213EXPORT_SYMBOL(rvt_restart_sge);
214
215