/*-
 * Copyright (c) 2002-2005 Sam Leffler, Errno Consulting
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    similar to the "NO WARRANTY" disclaimer below ("Disclaimer") and any
 *    redistribution must be conditioned upon including a substantially
 *    similar Disclaimer requirement for further binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * 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 NONINFRINGEMENT, MERCHANTIBILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR 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 DAMAGES.
 *
 * $Id$
 */

/*
 * Atsushi Onoe's rate control algorithm.
 */
#if !defined(AUTOCONF_INCLUDED) && !defined(CONFIG_LOCALVERSION)
#include <linux/config.h>
#endif
#include <linux/version.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/random.h>
#include <linux/delay.h>
#include <linux/cache.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/if_arp.h>

#include <asm/uaccess.h>

#include <net80211/if_media.h>
#include <net80211/ieee80211_var.h>
#include <net80211/ieee80211_rate.h>

#include "if_athvar.h"
#include "if_ath_hal.h"
#include "ah_desc.h"

#include "onoe.h"

#define	ONOE_DEBUG
#ifdef ONOE_DEBUG
enum {
	ATH_DEBUG_RATE	= 0x00000010,	/* rate control */
};
#define	DPRINTF(sc, _fmt, ...) do {				\
	if (sc->sc_debug & ATH_DEBUG_RATE)			\
		printk(_fmt, __VA_ARGS__);			\
} while (0)
#else
#define	DPRINTF(sc, _fmt, ...)
#endif

#include "release.h"
#if 0
static char *version = "1.0 (" RELEASE_VERSION ")";
#endif
static char *dev_info = "ath_rate_onoe";

/*
 * Default parameters for the rate control algorithm.  These are
 * all tunable with sysctls.  The rate controller runs periodically
 * (each ath_rateinterval ms) analyzing transmit statistics for each
 * neighbor/station (when operating in station mode this is only the AP).
 * If transmits look to be working well over a sampling period then
 * it gives a "raise rate credit".  If transmits look to not be working
 * well than it deducts a credit.  If the credits cross a threshold then
 * the transmit rate is raised.  Various error conditions force the
 * the transmit rate to be dropped.
 *
 * The decision to issue/deduct a credit is based on the errors and
 * retries accumulated over the sampling period.  ath_rate_raise defines
 * the percent of retransmits for which a credit is issued/deducted.
 * ath_rate_raise_threshold defines the threshold on credits at which
 * the transmit rate is increased.
 *
 * XXX this algorithm is flawed.
 */
static int ath_rateinterval = 1000;		/* rate ctl interval (ms) */
static int ath_rate_raise = 10;			/* add credit threshold */
static int ath_rate_raise_threshold = 10;	/* rate ctl raise threshold */

static void ath_rate_update(struct ath_softc *, struct ieee80211_node *, int);
static void ath_rate_ctl_start(struct ath_softc *, struct ieee80211_node *);
static void ath_rate_ctl(void *, struct ieee80211_node *);

static void
ath_rate_node_init(struct ath_softc *sc, struct ath_node *an)
{
	/* NB: assumed to be zero'd by caller */
	ath_rate_update(sc, &an->an_node, 0);
}

static void
ath_rate_node_cleanup(struct ath_softc *sc, struct ath_node *an)
{
}

static void
ath_rate_findrate(struct ath_softc *sc, struct ath_node *an,
	int shortPreamble, size_t frameLen,
	u_int8_t *rix, unsigned int *try0, u_int8_t *txrate)
{
	struct onoe_node *on = ATH_NODE_ONOE(an);

	*rix = on->on_tx_rix0;
	*try0 = on->on_tx_try0;
	if (shortPreamble)
		*txrate = on->on_tx_rate0sp;
	else
		*txrate = on->on_tx_rate0;
}

static void
ath_rate_get_mrr(struct ath_softc *sc, struct ath_node *an, int shortPreamble,
		 size_t frame_size, u_int8_t rix, struct ieee80211_mrr *mrr)
{
	struct onoe_node *on = ATH_NODE_ONOE(an);

	mrr->rate1 = on->on_tx_rate1sp;
	mrr->retries1 = 2;
	mrr->rate2 = on->on_tx_rate2sp;
	mrr->retries2 = 2;
	mrr->rate3 = on->on_tx_rate3sp;
	mrr->retries3 = 2;
}

static void
ath_rate_tx_complete(struct ath_softc *sc,
	struct ath_node *an, const struct ath_buf *bf)
{
	struct onoe_node *on = ATH_NODE_ONOE(an);
	const struct ath_tx_status *ts = &bf->bf_dsstatus.ds_txstat;

	if (ts->ts_status == 0)
		on->on_tx_ok++;
	else
		on->on_tx_err++;
	on->on_tx_retr += ts->ts_shortretry
			+ ts->ts_longretry;
	if (time_after_eq(jiffies, on->on_nextcheck)) {
		ath_rate_ctl(sc, &an->an_node);
		/* XXX halve rate for station mode */
		on->on_nextcheck = jiffies + (ath_rateinterval * HZ) / 1000;
	}
}

static void
ath_rate_newassoc(struct ath_softc *sc, struct ath_node *an, int isnew)
{
	if (isnew)
		ath_rate_ctl_start(sc, &an->an_node);
}

static void
ath_rate_update(struct ath_softc *sc, struct ieee80211_node *ni, int rate)
{
	struct ath_node *an = ATH_NODE(ni);
	struct onoe_node *on = ATH_NODE_ONOE(an);
	const HAL_RATE_TABLE *rt = sc->sc_currates;
	u_int8_t rix;

	KASSERT(rt != NULL, ("no rate table, mode %u", sc->sc_curmode));

	DPRINTF(sc, "%s: set xmit rate for " MAC_FMT " to %dM\n",
		__func__, MAC_ADDR(ni->ni_macaddr),
		ni->ni_rates.rs_nrates > 0 ?
			(ni->ni_rates.rs_rates[rate] & IEEE80211_RATE_VAL) / 2 : 0);

	ni->ni_txrate = rate;
	/*
	 * Before associating a node has no rate set setup
	 * so we can't calculate any transmit codes to use.
	 * This is ok since we should never be sending anything
	 * but management frames and those always go at the
	 * lowest hardware rate.
	 */
	if (ni->ni_rates.rs_nrates == 0)
		goto done;
	on->on_tx_rix0 = sc->sc_rixmap[ni->ni_rates.rs_rates[rate] & IEEE80211_RATE_VAL];
	on->on_tx_rate0 = rt->info[on->on_tx_rix0].rateCode;

	on->on_tx_rate0sp = on->on_tx_rate0 |
		rt->info[on->on_tx_rix0].shortPreamble;
	if (sc->sc_mrretry) {
		/*
		 * Hardware supports multi-rate retry; setup two
		 * step-down retry rates and make the lowest rate
		 * be the ``last chance''.  We use 4, 2, 2, 2 tries
		 * respectively (4 is set here, the rest are fixed
		 * in the xmit routine).
		 */
		on->on_tx_try0 = 1 + 3;		/* 4 tries at rate 0 */
		if (--rate >= 0) {
			rix = sc->sc_rixmap[ni->ni_rates.rs_rates[rate] & IEEE80211_RATE_VAL];
			on->on_tx_rate1 = rt->info[rix].rateCode;
			on->on_tx_rate1sp = on->on_tx_rate1 |
				rt->info[rix].shortPreamble;
		} else
			on->on_tx_rate1 = on->on_tx_rate1sp = 0;
		if (--rate >= 0) {
			rix = sc->sc_rixmap[ni->ni_rates.rs_rates[rate] & IEEE80211_RATE_VAL];
			on->on_tx_rate2 = rt->info[rix].rateCode;
			on->on_tx_rate2sp = on->on_tx_rate2 |
				rt->info[rix].shortPreamble;
		} else
			on->on_tx_rate2 = on->on_tx_rate2sp = 0;
		if (rate > 0) {
			/* NB: only do this if we didn't already do it above */
			on->on_tx_rate3 = rt->info[0].rateCode;
			on->on_tx_rate3sp =
				on->on_tx_rate3 | rt->info[0].shortPreamble;
		} else
			on->on_tx_rate3 = on->on_tx_rate3sp = 0;
	} else {
		on->on_tx_try0 = ATH_TXMAXTRY;	/* max tries at rate 0 */
		on->on_tx_rate1 = on->on_tx_rate1sp = 0;
		on->on_tx_rate2 = on->on_tx_rate2sp = 0;
		on->on_tx_rate3 = on->on_tx_rate3sp = 0;
	}
done:
	on->on_tx_ok = on->on_tx_err = on->on_tx_retr = on->on_tx_upper = 0;
}

/*
 * Set the starting transmit rate for a node.
 */
static void
ath_rate_ctl_start(struct ath_softc *sc, struct ieee80211_node *ni)
{
#define	RATE(_ix)	(ni->ni_rates.rs_rates[(_ix)] & IEEE80211_RATE_VAL)
	struct ieee80211vap *vap = ni->ni_vap;
	int srate;

	KASSERT(ni->ni_rates.rs_nrates > 0, ("no rates"));

	if (vap->iv_fixed_rate != IEEE80211_FIXED_RATE_NONE) {
		/*
		 * A fixed rate is to be used.  Find the corresponding
		 * index in the rate table.
		 */
		for (srate = 0; srate < ni->ni_rates.rs_nrates; srate++)
			if (vap->iv_fixed_rate ==
			    (ni->ni_rates.rs_rates[srate] & IEEE80211_RATE_VAL)) {
				ath_rate_update(sc, ni, srate);
				return;
			}

		printk(KERN_WARNING "%s: %s: fixed rate %u%sMbps is not "
		       "available and will be ignored\n", vap->iv_dev->name,
		       dev_info, vap->iv_fixed_rate / 2,
		       (vap->iv_fixed_rate & 1) ? ".5" : "");
	}

	/*
	 * No fixed rate is requested. For 11b start with
	 * the highest negotiated rate; otherwise, for 11g
	 * and 11a, we start "in the middle" at 24Mb or 36Mb.
	 */
	srate = ni->ni_rates.rs_nrates - 1;
	if (sc->sc_curmode != IEEE80211_MODE_11B) {
		/*
		 * Scan the negotiated rate set to find the
		 * closest rate.
		 */
		/* NB: the rate set is assumed sorted */
		for (; srate >= 0 && RATE(srate) > 72; srate--);
		KASSERT(srate >= 0, ("bogus rate set"));
	}

	ath_rate_update(sc, ni, srate);
#undef RATE
}

static void
ath_rate_cb(void *arg, struct ieee80211_node *ni)
{
	ath_rate_update(netdev_priv(ni->ni_ic->ic_dev), ni, (long) arg);
}

/*
 * Reset the rate control state for each 802.11 state transition.
 */
static void
ath_rate_newstate(struct ieee80211vap *vap, enum ieee80211_state state)
{
	struct ieee80211com *ic = vap->iv_ic;
	struct ath_softc *sc = netdev_priv(ic->ic_dev);
	struct ieee80211_node *ni;

	if (state == IEEE80211_S_INIT)
		return;
	if (vap->iv_opmode == IEEE80211_M_STA) {
		/*
		 * Reset local xmit state; this is really only
		 * meaningful when operating in station mode.
		 */
		ni = vap->iv_bss;
		if (state == IEEE80211_S_RUN) {
			ath_rate_ctl_start(sc, ni);
		} else {
			ath_rate_update(sc, ni, 0);
		}
	} else {
		/*
		 * When operating as a station the node table holds
		 * the APs that were discovered during scanning.
		 * For any other operating mode we want to reset the
		 * tx rate state of each node.
		 */
		ieee80211_iterate_nodes(&ic->ic_sta, ath_rate_cb, NULL);
		ath_rate_update(sc, vap->iv_bss, 0);
	}
}

/* 
 * Examine and potentially adjust the transmit rate.
 */
static void
ath_rate_ctl(void *arg, struct ieee80211_node *ni)
{
	struct ath_softc *sc = arg;
	struct onoe_node *on = ATH_NODE_ONOE(ATH_NODE(ni));
	struct ieee80211_rateset *rs = &ni->ni_rates;
	int dir = 0, nrate, enough;

	sc->sc_stats.ast_rate_calls++;

	/*
	 * Rate control
	 * XXX: very primitive version.
	 */
	enough = (on->on_tx_ok + on->on_tx_err >= 10);

	/* no packet reached -> down */
	if (on->on_tx_err > 0 && on->on_tx_ok == 0)
		dir = -1;

	/* all packets needs retry in average -> down */
	if (enough && on->on_tx_ok < on->on_tx_retr)
		dir = -1;

	/* no error and less than rate_raise% of packets need retry -> up */
	if (enough && on->on_tx_err == 0 &&
	    on->on_tx_retr < (on->on_tx_ok * ath_rate_raise) / 100)
		dir = 1;

	DPRINTF(sc, MAC_FMT ": ok %d err %d retr %d upper %d dir %d\n",
		MAC_ADDR(ni->ni_macaddr),
		on->on_tx_ok, on->on_tx_err, on->on_tx_retr,
		on->on_tx_upper, dir);

	nrate = ni->ni_txrate;
	switch (dir) {
	case 0:
		if (enough && on->on_tx_upper > 0)
			on->on_tx_upper--;
		break;
	case -1:
		if (nrate > 0) {
			nrate--;
			sc->sc_stats.ast_rate_drop++;
		}
		on->on_tx_upper = 0;
		break;
	case 1:
		/* raise rate if we hit rate_raise_threshold */
		if (++on->on_tx_upper < ath_rate_raise_threshold)
			break;
		on->on_tx_upper = 0;
		if (nrate + 1 < rs->rs_nrates) {
			nrate++;
			sc->sc_stats.ast_rate_raise++;
		}
		break;
	}

	if (nrate != ni->ni_txrate) {
		DPRINTF(sc, "%s: %dM -> %dM (%d ok, %d err, %d retr)\n",
		    __func__,
		    (rs->rs_rates[ni->ni_txrate] & IEEE80211_RATE_VAL) / 2,
		    (rs->rs_rates[nrate] & IEEE80211_RATE_VAL) / 2,
		    on->on_tx_ok, on->on_tx_err, on->on_tx_retr);
		ath_rate_update(sc, ni, nrate);
	} else if (enough)
		on->on_tx_ok = on->on_tx_err = on->on_tx_retr = 0;
}

static struct ath_ratectrl *
ath_rate_attach(struct ath_softc *sc)
{
	struct onoe_softc *osc;

	_MOD_INC_USE(THIS_MODULE, return NULL);
	osc = kmalloc(sizeof(struct onoe_softc), GFP_ATOMIC);
	if (osc == NULL) {
		_MOD_DEC_USE(THIS_MODULE);
		return NULL;
	}
	osc->arc.arc_space = sizeof(struct onoe_node);
	osc->arc.arc_vap_space = 0;

	return &osc->arc;
}

static void
ath_rate_detach(struct ath_ratectrl *arc)
{
	struct onoe_softc *osc = (struct onoe_softc *)arc;

	kfree(osc);
	_MOD_DEC_USE(THIS_MODULE);
}

static int minrateinterval = 500;	/* 500ms */
static int maxpercent = 100;		/* 100% */
static int minpercent = 0;		/* 0% */
static int maxint = 0x7fffffff;		/* 32-bit big */

/*
 * Static (i.e. global) sysctls.
 */
static ctl_table ath_rate_static_sysctls[] = {
	{ ATH_INIT_CTL_NAME(CTL_AUTO)
	  .procname	= "interval",
	  .mode		= 0644,
	  .data		= &ath_rateinterval,
	  .maxlen	= sizeof(ath_rateinterval),
	  .extra1	= &minrateinterval,
	  .extra2	= &maxint,
	  .proc_handler	= proc_dointvec_minmax
	},
	{ ATH_INIT_CTL_NAME(CTL_AUTO)
	  .procname	= "raise",
	  .mode		= 0644,
	  .data		= &ath_rate_raise,
	  .maxlen	= sizeof(ath_rate_raise),
	  .extra1	= &minpercent,
	  .extra2	= &maxpercent,
	  .proc_handler	= proc_dointvec_minmax
	},
	{ ATH_INIT_CTL_NAME(CTL_AUTO)
	  .procname	= "raise_threshold",
	  .mode		= 0644,
	  .data		= &ath_rate_raise_threshold,
	  .maxlen	= sizeof(ath_rate_raise_threshold),
	  .proc_handler	= proc_dointvec
	},
	{ }
};
static ctl_table ath_rate_table[] = {
	{ ATH_INIT_CTL_NAME(CTL_AUTO)
	  .procname	= "rate_onoe",
	  .mode		= 0555,
	  .child	= ath_rate_static_sysctls
	}, { }
};
static ctl_table ath_ath_table[] = {
	{ ATH_INIT_CTL_NAME(DEV_ATH)
	  .procname	= "ath",
	  .mode		= 0555,
	  .child	= ath_rate_table
	}, { }
};
static ctl_table ath_root_table[] = {
	{ ATH_INIT_CTL_NAME(CTL_DEV)
	  .procname	= "dev",
	  .mode		= 0555,
	  .child	= ath_ath_table
	}, { }
};
static struct ctl_table_header *ath_sysctl_header;

static struct ieee80211_rate_ops ath_rate_ops = {
	.ratectl_id = IEEE80211_RATE_ONOE,
	.node_init = ath_rate_node_init,
	.node_cleanup = ath_rate_node_cleanup,
	.findrate = ath_rate_findrate,
	.get_mrr = ath_rate_get_mrr,
	.tx_complete = ath_rate_tx_complete,
	.newassoc = ath_rate_newassoc,
	.newstate = ath_rate_newstate,
	.attach = ath_rate_attach,
	.detach = ath_rate_detach,
};

MODULE_AUTHOR("Errno Consulting, Sam Leffler");
MODULE_DESCRIPTION("Atsushi Onoe's rate control algorithm for Atheros devices");
#ifdef MODULE_VERSION
MODULE_VERSION(RELEASE_VERSION);
#endif
#ifdef MODULE_LICENSE
MODULE_LICENSE("Dual BSD/GPL");
#endif

static int __init
init_ath_rate_onoe(void)
{
	int ret = ieee80211_rate_register(&ath_rate_ops);
	if (ret)
		return ret;

	ath_sysctl_header = ATH_REGISTER_SYSCTL_TABLE(ath_root_table);
	return (0);
}
module_init(init_ath_rate_onoe);

static void __exit
exit_ath_rate_onoe(void)
{
	if (ath_sysctl_header != NULL)
		unregister_sysctl_table(ath_sysctl_header);
	ieee80211_rate_unregister(&ath_rate_ops);
}
module_exit(exit_ath_rate_onoe);