Atheros AR600x driver + build glue

chromeos/drivers/ath6kl/miscdrv/credit_dist.c

+//------------------------------------------------------------------------------
+// <copyright file="credit_dist.c" company="Atheros">
+//    Copyright (c) 2004-2008 Atheros Corporation.  All rights reserved.
+// 
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 2 as
+// published by the Free Software Foundation;
+//
+// Software distributed under the License is distributed on an "AS
+// IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+// implied. See the License for the specific language governing
+// rights and limitations under the License.
+//
+//
+//------------------------------------------------------------------------------
+//==============================================================================
+// 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 */
+
+#ifdef NO_VO_SERVICE
+#define DATA_SVCS_USED 3
+#else
+#define DATA_SVCS_USED 4
+#endif
+
+static void RedistributeCredits(COMMON_CREDIT_STATE_INFO *pCredInfo,
+                                HTC_ENDPOINT_CREDIT_DIST *pEPDistList);
+
+static void SeekCredits(COMMON_CREDIT_STATE_INFO *pCredInfo,
+                        HTC_ENDPOINT_CREDIT_DIST *pEPDistList);
+
+/* reduce an ep's credits back to a set limit */
+static INLINE void ReduceCredits(COMMON_CREDIT_STATE_INFO *pCredInfo,
+                                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,
+                               HTC_ENDPOINT_CREDIT_DIST *pEPList,
+                               int                      TotalCredits)
+{
+    HTC_ENDPOINT_CREDIT_DIST *pCurEpDist;
+    int                      count;
+    COMMON_CREDIT_STATE_INFO *pCredInfo = (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;
+
+        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,
+                                     HTC_ENDPOINT_CREDIT_DIST *pEPDistList,
+                                     HTC_CREDIT_DIST_REASON   Reason)
+{
+    HTC_ENDPOINT_CREDIT_DIST *pCurEpDist;
+    COMMON_CREDIT_STATE_INFO *pCredInfo = (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(COMMON_CREDIT_STATE_INFO *pCredInfo,
+                                HTC_ENDPOINT_CREDIT_DIST *pEPDistList)
+{
+    HTC_ENDPOINT_CREDIT_DIST *pCurEpDist = pEPDistList;
+
+        /* walk through the list and remove credits from inactive endpoints */
+    while (pCurEpDist != NULL) {
+
+        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(COMMON_CREDIT_STATE_INFO *pCredInfo,
+                        HTC_ENDPOINT_CREDIT_DIST *pEPDist)
+{
+    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;
+        }
+
+        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;
+            }
+        }
+
+        /* 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 fullfill 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 fullfill our need
+                     * try to take away just enough to fullfill 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 */
+A_STATUS ar6000_setup_credit_dist(HTC_HANDLE HTCHandle, COMMON_CREDIT_STATE_INFO *pCredInfo)
+{
+    HTC_SERVICE_ID servicepriority[5];
+
+    A_MEMZERO(pCredInfo,sizeof(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 A_OK;
+}
+