//------------------------------------------------------------------------------
// <copyright file="credit_dist.c" company="Atheros">
// Copyright (c) 2004-2010 Atheros Corporation. All rights reserved.
//
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
//
//
//------------------------------------------------------------------------------
//==============================================================================
// Author(s): ="Atheros"
//==============================================================================
#include "a_config.h"
#include "athdefs.h"
#include "a_types.h"
#include "a_osapi.h"
#define ATH_MODULE_NAME misc
#include "a_debug.h"
#include "htc_api.h"
#include "common_drv.h"
/********* CREDIT DISTRIBUTION FUNCTIONS ******************************************/
#define NO_VO_SERVICE 1 /* currently WMI only uses 3 data streams, so we leave VO service inactive */
#define CONFIG_GIVE_LOW_PRIORITY_STREAMS_MIN_CREDITS 1
#ifdef NO_VO_SERVICE
#define DATA_SVCS_USED 3
#else
#define DATA_SVCS_USED 4
#endif
static void RedistributeCredits(struct common_credit_state_info *pCredInfo,
struct htc_endpoint_credit_dist *pEPDistList);
static void SeekCredits(struct common_credit_state_info *pCredInfo,
struct htc_endpoint_credit_dist *pEPDistList);
/* reduce an ep's credits back to a set limit */
static INLINE void ReduceCredits(struct common_credit_state_info *pCredInfo,
struct htc_endpoint_credit_dist *pEpDist,
int Limit)
{
int credits;
/* set the new limit */
pEpDist->TxCreditsAssigned = Limit;
if (pEpDist->TxCredits <= Limit) {
return;
}
/* figure out how much to take away */
credits = pEpDist->TxCredits - Limit;
/* take them away */
pEpDist->TxCredits -= credits;
pCredInfo->CurrentFreeCredits += credits;
}
/* give an endpoint some credits from the free credit pool */
#define GiveCredits(pCredInfo,pEpDist,credits) \
{ \
(pEpDist)->TxCredits += (credits); \
(pEpDist)->TxCreditsAssigned += (credits); \
(pCredInfo)->CurrentFreeCredits -= (credits); \
}
/* default credit init callback.
* This function is called in the context of HTCStart() to setup initial (application-specific)
* credit distributions */
static void ar6000_credit_init(void *Context,
struct htc_endpoint_credit_dist *pEPList,
int TotalCredits)
{
struct htc_endpoint_credit_dist *pCurEpDist;
int count;
struct common_credit_state_info *pCredInfo = (struct common_credit_state_info *)Context;
pCredInfo->CurrentFreeCredits = TotalCredits;
pCredInfo->TotalAvailableCredits = TotalCredits;
pCurEpDist = pEPList;
/* run through the list and initialize */
while (pCurEpDist != NULL) {
/* set minimums for each endpoint */
pCurEpDist->TxCreditsMin = pCurEpDist->TxCreditsPerMaxMsg;
#ifdef CONFIG_GIVE_LOW_PRIORITY_STREAMS_MIN_CREDITS
if (TotalCredits > 4)
{
if ((pCurEpDist->ServiceID == WMI_DATA_BK_SVC) || (pCurEpDist->ServiceID == WMI_DATA_BE_SVC)){
/* assign at least min credits to lower than VO priority services */
GiveCredits(pCredInfo,pCurEpDist,pCurEpDist->TxCreditsMin);
/* force active */
SET_EP_ACTIVE(pCurEpDist);
}
}
#endif
if (pCurEpDist->ServiceID == WMI_CONTROL_SVC) {
/* give control service some credits */
GiveCredits(pCredInfo,pCurEpDist,pCurEpDist->TxCreditsMin);
/* control service is always marked active, it never goes inactive EVER */
SET_EP_ACTIVE(pCurEpDist);
} else if (pCurEpDist->ServiceID == WMI_DATA_BK_SVC) {
/* this is the lowest priority data endpoint, save this off for easy access */
pCredInfo->pLowestPriEpDist = pCurEpDist;
}
/* Streams have to be created (explicit | implicit)for all kinds
* of traffic. BE endpoints are also inactive in the beginning.
* When BE traffic starts it creates implicit streams that
* redistributes credits.
*/
/* note, all other endpoints have minimums set but are initially given NO credits.
* Credits will be distributed as traffic activity demands */
pCurEpDist = pCurEpDist->pNext;
}
if (pCredInfo->CurrentFreeCredits <= 0) {
AR_DEBUG_PRINTF(ATH_LOG_INF, ("Not enough credits (%d) to do credit distributions \n", TotalCredits));
A_ASSERT(false);
return;
}
/* reset list */
pCurEpDist = pEPList;
/* now run through the list and set max operating credit limits for everyone */
while (pCurEpDist != NULL) {
if (pCurEpDist->ServiceID == WMI_CONTROL_SVC) {
/* control service max is just 1 max message */
pCurEpDist->TxCreditsNorm = pCurEpDist->TxCreditsPerMaxMsg;
} else {
/* for the remaining data endpoints, we assume that each TxCreditsPerMaxMsg are
* the same.
* We use a simple calculation here, we take the remaining credits and
* determine how many max messages this can cover and then set each endpoint's
* normal value equal to 3/4 this amount.
* */
count = (pCredInfo->CurrentFreeCredits/pCurEpDist->TxCreditsPerMaxMsg) * pCurEpDist->TxCreditsPerMaxMsg;
count = (count * 3) >> 2;
count = max(count,pCurEpDist->TxCreditsPerMaxMsg);
/* set normal */
pCurEpDist->TxCreditsNorm = count;
}
pCurEpDist = pCurEpDist->pNext;
}
}
/* default credit distribution callback
* This callback is invoked whenever endpoints require credit distributions.
* A lock is held while this function is invoked, this function shall NOT block.
* The pEPDistList is a list of distribution structures in prioritized order as
* defined by the call to the HTCSetCreditDistribution() api.
*
*/
static void ar6000_credit_distribute(void *Context,
struct htc_endpoint_credit_dist *pEPDistList,
HTC_CREDIT_DIST_REASON Reason)
{
struct htc_endpoint_credit_dist *pCurEpDist;
struct common_credit_state_info *pCredInfo = (struct common_credit_state_info *)Context;
switch (Reason) {
case HTC_CREDIT_DIST_SEND_COMPLETE :
pCurEpDist = pEPDistList;
/* we are given the start of the endpoint distribution list.
* There may be one or more endpoints to service.
* Run through the list and distribute credits */
while (pCurEpDist != NULL) {
if (pCurEpDist->TxCreditsToDist > 0) {
/* return the credits back to the endpoint */
pCurEpDist->TxCredits += pCurEpDist->TxCreditsToDist;
/* always zero out when we are done */
pCurEpDist->TxCreditsToDist = 0;
if (pCurEpDist->TxCredits > pCurEpDist->TxCreditsAssigned) {
/* reduce to the assigned limit, previous credit reductions
* could have caused the limit to change */
ReduceCredits(pCredInfo, pCurEpDist, pCurEpDist->TxCreditsAssigned);
}
if (pCurEpDist->TxCredits > pCurEpDist->TxCreditsNorm) {
/* oversubscribed endpoints need to reduce back to normal */
ReduceCredits(pCredInfo, pCurEpDist, pCurEpDist->TxCreditsNorm);
}
if (!IS_EP_ACTIVE(pCurEpDist)) {
/* endpoint is inactive, now check for messages waiting for credits */
if (pCurEpDist->TxQueueDepth == 0) {
/* EP is inactive and there are no pending messages,
* reduce credits back to zero to recover credits */
ReduceCredits(pCredInfo, pCurEpDist, 0);
}
}
}
pCurEpDist = pCurEpDist->pNext;
}
break;
case HTC_CREDIT_DIST_ACTIVITY_CHANGE :
RedistributeCredits(pCredInfo,pEPDistList);
break;
case HTC_CREDIT_DIST_SEEK_CREDITS :
SeekCredits(pCredInfo,pEPDistList);
break;
case HTC_DUMP_CREDIT_STATE :
AR_DEBUG_PRINTF(ATH_DEBUG_ERR, ("Credit Distribution, total : %d, free : %d\n",
pCredInfo->TotalAvailableCredits, pCredInfo->CurrentFreeCredits));
break;
default:
break;
}
/* sanity checks done after each distribution action */
A_ASSERT(pCredInfo->CurrentFreeCredits <= pCredInfo->TotalAvailableCredits);
A_ASSERT(pCredInfo->CurrentFreeCredits >= 0);
}
/* redistribute credits based on activity change */
static void RedistributeCredits(struct common_credit_state_info *pCredInfo,
struct htc_endpoint_credit_dist *pEPDistList)
{
struct htc_endpoint_credit_dist *pCurEpDist = pEPDistList;
/* walk through the list and remove credits from inactive endpoints */
while (pCurEpDist != NULL) {
#ifdef CONFIG_GIVE_LOW_PRIORITY_STREAMS_MIN_CREDITS
if ((pCurEpDist->ServiceID == WMI_DATA_BK_SVC) || (pCurEpDist->ServiceID == WMI_DATA_BE_SVC)) {
/* force low priority streams to always be active to retain their minimum credit distribution */
SET_EP_ACTIVE(pCurEpDist);
}
#endif
if (pCurEpDist->ServiceID != WMI_CONTROL_SVC) {
if (!IS_EP_ACTIVE(pCurEpDist)) {
if (pCurEpDist->TxQueueDepth == 0) {
/* EP is inactive and there are no pending messages, reduce credits back to zero */
ReduceCredits(pCredInfo, pCurEpDist, 0);
} else {
/* we cannot zero the credits assigned to this EP, but to keep
* the credits available for these leftover packets, reduce to
* a minimum */
ReduceCredits(pCredInfo, pCurEpDist, pCurEpDist->TxCreditsMin);
}
}
}
/* NOTE in the active case, we do not need to do anything further,
* when an EP goes active and needs credits, HTC will call into
* our distribution function using a reason code of HTC_CREDIT_DIST_SEEK_CREDITS */
pCurEpDist = pCurEpDist->pNext;
}
}
/* HTC has an endpoint that needs credits, pEPDist is the endpoint in question */
static void SeekCredits(struct common_credit_state_info *pCredInfo,
struct htc_endpoint_credit_dist *pEPDist)
{
struct htc_endpoint_credit_dist *pCurEpDist;
int credits = 0;
int need;
do {
if (pEPDist->ServiceID == WMI_CONTROL_SVC) {
/* we never oversubscribe on the control service, this is not
* a high performance path and the target never holds onto control
* credits for too long */
break;
}
#ifdef CONFIG_GIVE_LOW_PRIORITY_STREAMS_MIN_CREDITS
if (pEPDist->ServiceID == WMI_DATA_VI_SVC) {
if ((pEPDist->TxCreditsAssigned >= pEPDist->TxCreditsNorm)) {
/* limit VI service from oversubscribing */
break;
}
}
if (pEPDist->ServiceID == WMI_DATA_VO_SVC) {
if ((pEPDist->TxCreditsAssigned >= pEPDist->TxCreditsNorm)) {
/* limit VO service from oversubscribing */
break;
}
}
#else
if (pEPDist->ServiceID == WMI_DATA_VI_SVC) {
if ((pEPDist->TxCreditsAssigned >= pEPDist->TxCreditsNorm) ||
(pCredInfo->CurrentFreeCredits <= pEPDist->TxCreditsPerMaxMsg)) {
/* limit VI service from oversubscribing */
/* at least one free credit will not be used by VI */
break;
}
}
if (pEPDist->ServiceID == WMI_DATA_VO_SVC) {
if ((pEPDist->TxCreditsAssigned >= pEPDist->TxCreditsNorm) ||
(pCredInfo->CurrentFreeCredits <= pEPDist->TxCreditsPerMaxMsg)) {
/* limit VO service from oversubscribing */
/* at least one free credit will not be used by VO */
break;
}
}
#endif
/* for all other services, we follow a simple algorithm of
* 1. checking the free pool for credits
* 2. checking lower priority endpoints for credits to take */
/* give what we can */
credits = min(pCredInfo->CurrentFreeCredits,pEPDist->TxCreditsSeek);
if (credits >= pEPDist->TxCreditsSeek) {
/* we found some to fulfill the seek request */
break;
}
/* we don't have enough in the free pool, try taking away from lower priority services
*
* The rule for taking away credits:
* 1. Only take from lower priority endpoints
* 2. Only take what is allocated above the minimum (never starve an endpoint completely)
* 3. Only take what you need.
*
* */
/* starting at the lowest priority */
pCurEpDist = pCredInfo->pLowestPriEpDist;
/* work backwards until we hit the endpoint again */
while (pCurEpDist != pEPDist) {
/* calculate how many we need so far */
need = pEPDist->TxCreditsSeek - pCredInfo->CurrentFreeCredits;
if ((pCurEpDist->TxCreditsAssigned - need) >= pCurEpDist->TxCreditsMin) {
/* the current one has been allocated more than it's minimum and it
* has enough credits assigned above it's minimum to fulfill our need
* try to take away just enough to fulfill our need */
ReduceCredits(pCredInfo,
pCurEpDist,
pCurEpDist->TxCreditsAssigned - need);
if (pCredInfo->CurrentFreeCredits >= pEPDist->TxCreditsSeek) {
/* we have enough */
break;
}
}
pCurEpDist = pCurEpDist->pPrev;
}
/* return what we can get */
credits = min(pCredInfo->CurrentFreeCredits,pEPDist->TxCreditsSeek);
} while (false);
/* did we find some credits? */
if (credits) {
/* give what we can */
GiveCredits(pCredInfo, pEPDist, credits);
}
}
/* initialize and setup credit distribution */
int ar6000_setup_credit_dist(HTC_HANDLE HTCHandle, struct common_credit_state_info *pCredInfo)
{
HTC_SERVICE_ID servicepriority[5];
A_MEMZERO(pCredInfo,sizeof(struct common_credit_state_info));
servicepriority[0] = WMI_CONTROL_SVC; /* highest */
servicepriority[1] = WMI_DATA_VO_SVC;
servicepriority[2] = WMI_DATA_VI_SVC;
servicepriority[3] = WMI_DATA_BE_SVC;
servicepriority[4] = WMI_DATA_BK_SVC; /* lowest */
/* set callbacks and priority list */
HTCSetCreditDistribution(HTCHandle,
pCredInfo,
ar6000_credit_distribute,
ar6000_credit_init,
servicepriority,
5);
return 0;
}
