1// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
2/*
3 * Copyright(c) 2016 Intel Corporation.
4 */
5
6#include <rdma/rdmavt_qp.h>
7#include <rdma/ib_hdrs.h>
8
9/*
10 * Convert the AETH credit code into the number of credits.
11 */
12static const u16 credit_table[31] = {
13	0,                      /* 0 */
14	1,                      /* 1 */
15	2,                      /* 2 */
16	3,                      /* 3 */
17	4,                      /* 4 */
18	6,                      /* 5 */
19	8,                      /* 6 */
20	12,                     /* 7 */
21	16,                     /* 8 */
22	24,                     /* 9 */
23	32,                     /* A */
24	48,                     /* B */
25	64,                     /* C */
26	96,                     /* D */
27	128,                    /* E */
28	192,                    /* F */
29	256,                    /* 10 */
30	384,                    /* 11 */
31	512,                    /* 12 */
32	768,                    /* 13 */
33	1024,                   /* 14 */
34	1536,                   /* 15 */
35	2048,                   /* 16 */
36	3072,                   /* 17 */
37	4096,                   /* 18 */
38	6144,                   /* 19 */
39	8192,                   /* 1A */
40	12288,                  /* 1B */
41	16384,                  /* 1C */
42	24576,                  /* 1D */
43	32768                   /* 1E */
44};
45
46/**
47 * rvt_compute_aeth - compute the AETH (syndrome + MSN)
48 * @qp: the queue pair to compute the AETH for
49 *
50 * Returns the AETH.
51 */
52__be32 rvt_compute_aeth(struct rvt_qp *qp)
53{
54	u32 aeth = qp->r_msn & IB_MSN_MASK;
55
56	if (qp->ibqp.srq) {
57		/*
58		 * Shared receive queues don't generate credits.
59		 * Set the credit field to the invalid value.
60		 */
61		aeth |= IB_AETH_CREDIT_INVAL << IB_AETH_CREDIT_SHIFT;
62	} else {
63		u32 min, max, x;
64		u32 credits;
65		u32 head;
66		u32 tail;
67
68		credits = READ_ONCE(qp->r_rq.kwq->count);
69		if (credits == 0) {
70			/* sanity check pointers before trusting them */
71			if (qp->ip) {
72				head = RDMA_READ_UAPI_ATOMIC(qp->r_rq.wq->head);
73				tail = RDMA_READ_UAPI_ATOMIC(qp->r_rq.wq->tail);
74			} else {
75				head = READ_ONCE(qp->r_rq.kwq->head);
76				tail = READ_ONCE(qp->r_rq.kwq->tail);
77			}
78			if (head >= qp->r_rq.size)
79				head = 0;
80			if (tail >= qp->r_rq.size)
81				tail = 0;
82			/*
83			 * Compute the number of credits available (RWQEs).
84			 * There is a small chance that the pair of reads are
85			 * not atomic, which is OK, since the fuzziness is
86			 * resolved as further ACKs go out.
87			 */
88			credits = rvt_get_rq_count(&qp->r_rq, head, tail);
89		}
90		/*
91		 * Binary search the credit table to find the code to
92		 * use.
93		 */
94		min = 0;
95		max = 31;
96		for (;;) {
97			x = (min + max) / 2;
98			if (credit_table[x] == credits)
99				break;
100			if (credit_table[x] > credits) {
101				max = x;
102			} else {
103				if (min == x)
104					break;
105				min = x;
106			}
107		}
108		aeth |= x << IB_AETH_CREDIT_SHIFT;
109	}
110	return cpu_to_be32(aeth);
111}
112EXPORT_SYMBOL(rvt_compute_aeth);
113
114/**
115 * rvt_get_credit - flush the send work queue of a QP
116 * @qp: the qp who's send work queue to flush
117 * @aeth: the Acknowledge Extended Transport Header
118 *
119 * The QP s_lock should be held.
120 */
121void rvt_get_credit(struct rvt_qp *qp, u32 aeth)
122{
123	struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
124	u32 credit = (aeth >> IB_AETH_CREDIT_SHIFT) & IB_AETH_CREDIT_MASK;
125
126	lockdep_assert_held(&qp->s_lock);
127	/*
128	 * If the credit is invalid, we can send
129	 * as many packets as we like.  Otherwise, we have to
130	 * honor the credit field.
131	 */
132	if (credit == IB_AETH_CREDIT_INVAL) {
133		if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT)) {
134			qp->s_flags |= RVT_S_UNLIMITED_CREDIT;
135			if (qp->s_flags & RVT_S_WAIT_SSN_CREDIT) {
136				qp->s_flags &= ~RVT_S_WAIT_SSN_CREDIT;
137				rdi->driver_f.schedule_send(qp);
138			}
139		}
140	} else if (!(qp->s_flags & RVT_S_UNLIMITED_CREDIT)) {
141		/* Compute new LSN (i.e., MSN + credit) */
142		credit = (aeth + credit_table[credit]) & IB_MSN_MASK;
143		if (rvt_cmp_msn(credit, qp->s_lsn) > 0) {
144			qp->s_lsn = credit;
145			if (qp->s_flags & RVT_S_WAIT_SSN_CREDIT) {
146				qp->s_flags &= ~RVT_S_WAIT_SSN_CREDIT;
147				rdi->driver_f.schedule_send(qp);
148			}
149		}
150	}
151}
152EXPORT_SYMBOL(rvt_get_credit);
153
154/**
155 * rvt_restart_sge - rewind the sge state for a wqe
156 * @ss: the sge state pointer
157 * @wqe: the wqe to rewind
158 * @len: the data length from the start of the wqe in bytes
159 *
160 * Returns the remaining data length.
161 */
162u32 rvt_restart_sge(struct rvt_sge_state *ss, struct rvt_swqe *wqe, u32 len)
163{
164	ss->sge = wqe->sg_list[0];
165	ss->sg_list = wqe->sg_list + 1;
166	ss->num_sge = wqe->wr.num_sge;
167	ss->total_len = wqe->length;
168	rvt_skip_sge(ss, len, false);
169	return wqe->length - len;
170}
171EXPORT_SYMBOL(rvt_restart_sge);
172
173