1/*	$OpenBSD: ieee80211_amrr.c,v 1.12 2019/02/24 09:36:28 stsp Exp $	*/
2
3/*-
4 * Copyright (c) 2006
5 *	Damien Bergamini <damien.bergamini@free.fr>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20#include <sys/param.h>
21#include <sys/systm.h>
22#include <sys/kernel.h>
23#include <sys/socket.h>
24
25#include <net/if.h>
26#include <net/if_media.h>
27
28#include <netinet/in.h>
29#include <netinet/if_ether.h>
30
31#include <net80211/ieee80211_var.h>
32#include <net80211/ieee80211_priv.h>
33#include <net80211/ieee80211_amrr.h>
34
35#define is_success(amn)	\
36	((amn)->amn_retrycnt < (amn)->amn_txcnt / 10)
37#define is_failure(amn)	\
38	((amn)->amn_retrycnt > (amn)->amn_txcnt / 3)
39#define is_enough(amn)		\
40	((amn)->amn_txcnt > 10)
41#define reset_cnt(amn)		\
42	do { (amn)->amn_txcnt = (amn)->amn_retrycnt = 0; } while (0)
43
44static inline int
45is_min_rate(struct ieee80211_node *ni)
46{
47	return (ni->ni_txrate == 0);
48}
49
50static inline int
51is_max_rate(struct ieee80211_node *ni)
52{
53	return (ni->ni_txrate == ni->ni_rates.rs_nrates - 1);
54}
55
56static inline void
57increase_rate(struct ieee80211_node *ni)
58{
59	ni->ni_txrate++;
60}
61
62static inline void
63decrease_rate(struct ieee80211_node *ni)
64{
65	ni->ni_txrate--;
66}
67
68void
69ieee80211_amrr_node_init(const struct ieee80211_amrr *amrr,
70    struct ieee80211_amrr_node *amn)
71{
72	amn->amn_success = 0;
73	amn->amn_recovery = 0;
74	amn->amn_txcnt = amn->amn_retrycnt = 0;
75	amn->amn_success_threshold = amrr->amrr_min_success_threshold;
76}
77
78/*
79 * Update ni->ni_txrate.
80 */
81void
82ieee80211_amrr_choose(struct ieee80211_amrr *amrr, struct ieee80211_node *ni,
83    struct ieee80211_amrr_node *amn)
84{
85#define RV(rate)	((rate) & IEEE80211_RATE_VAL)
86	int need_change = 0;
87
88	if (is_success(amn) && is_enough(amn)) {
89		amn->amn_success++;
90		if (amn->amn_success >= amn->amn_success_threshold &&
91		    !is_max_rate(ni)) {
92			amn->amn_recovery = 1;
93			amn->amn_success = 0;
94			increase_rate(ni);
95			DPRINTF(("increase rate=%d,#tx=%d,#retries=%d\n",
96			    RV(ni->ni_rates.rs_rates[ni->ni_txrate]),
97			    amn->amn_txcnt, amn->amn_retrycnt));
98			need_change = 1;
99		} else {
100			amn->amn_recovery = 0;
101		}
102	} else if (is_failure(amn)) {
103		amn->amn_success = 0;
104		if (!is_min_rate(ni)) {
105			if (amn->amn_recovery) {
106				amn->amn_success_threshold *= 2;
107				if (amn->amn_success_threshold >
108				    amrr->amrr_max_success_threshold)
109					amn->amn_success_threshold =
110					    amrr->amrr_max_success_threshold;
111			} else {
112				amn->amn_success_threshold =
113				    amrr->amrr_min_success_threshold;
114			}
115			decrease_rate(ni);
116			DPRINTF(("decrease rate=%d,#tx=%d,#retries=%d\n",
117			    RV(ni->ni_rates.rs_rates[ni->ni_txrate]),
118			    amn->amn_txcnt, amn->amn_retrycnt));
119			need_change = 1;
120		}
121		amn->amn_recovery = 0;
122	}
123
124	if (is_enough(amn) || need_change)
125		reset_cnt(amn);
126#undef RV
127}
128