drivers/net/ixgbe/ixgbe_dcb.c

   1 /*******************************************************************************
   2
   3   Intel 10 Gigabit PCI Express Linux driver
   4   Copyright(c) 1999 - 2010 Intel Corporation.
   5
   6   This program is free software; you can redistribute it and/or modify it
   7   under the terms and conditions of the GNU General Public License,
   8   version 2, as published by the Free Software Foundation.
   9
  10   This program is distributed in the hope it will be useful, but WITHOUT
  11   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  13   more details.
  14
  15   You should have received a copy of the GNU General Public License along with
  16   this program; if not, write to the Free Software Foundation, Inc.,
  17   51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  18
  19   The full GNU General Public License is included in this distribution in
  20   the file called "COPYING".
  21
  22   Contact Information:
  23   Linux NICS <linux.nics@intel.com>
  24   e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
  25   Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497
  26
  27 *******************************************************************************/
  28
  29
  30 #include "ixgbe.h"
  31 #include "ixgbe_type.h"
  32 #include "ixgbe_dcb.h"
  33 #include "ixgbe_dcb_82598.h"
  34 #include "ixgbe_dcb_82599.h"
  35
  36 /**
  37  * ixgbe_dcb_calculate_tc_credits - Calculates traffic class credits
  38  * @ixgbe_dcb_config: Struct containing DCB settings.
  39  * @direction: Configuring either Tx or Rx.
  40  *
  41  * This function calculates the credits allocated to each traffic class.
  42  * It should be called only after the rules are checked by
  43  * ixgbe_dcb_check_config().
  44  */
  45 s32 ixgbe_dcb_calculate_tc_credits(struct ixgbe_hw *hw,
  46                                    struct ixgbe_dcb_config *dcb_config,
  47                                    int max_frame, u8 direction)
  48 {
  49         struct tc_bw_alloc *p;
  50         int min_credit;
  51         int min_multiplier;
  52         int min_percent = 100;
  53         s32 ret_val = 0;
  54         /* Initialization values default for Tx settings */
  55         u32 credit_refill       = 0;
  56         u32 credit_max          = 0;
  57         u16 link_percentage     = 0;
  58         u8  bw_percent          = 0;
  59         u8  i;
  60
  61         if (dcb_config == NULL) {
  62                 ret_val = DCB_ERR_CONFIG;
  63                 goto out;
  64         }
  65
  66         min_credit = ((max_frame / 2) + DCB_CREDIT_QUANTUM - 1) /
  67                         DCB_CREDIT_QUANTUM;
  68
  69         /* Find smallest link percentage */
  70         for (i = 0; i < MAX_TRAFFIC_CLASS; i++) {
  71                 p = &dcb_config->tc_config[i].path[direction];
  72                 bw_percent = dcb_config->bw_percentage[direction][p->bwg_id];
  73                 link_percentage = p->bwg_percent;
  74
  75                 link_percentage = (link_percentage * bw_percent) / 100;
  76
  77                 if (link_percentage && link_percentage < min_percent)
  78                         min_percent = link_percentage;
  79         }
  80
  81         /*
  82          * The ratio between traffic classes will control the bandwidth
  83          * percentages seen on the wire. To calculate this ratio we use
  84          * a multiplier. It is required that the refill credits must be
  85          * larger than the max frame size so here we find the smallest
  86          * multiplier that will allow all bandwidth percentages to be
  87          * greater than the max frame size.
  88          */
  89         min_multiplier = (min_credit / min_percent) + 1;
  90
  91         /* Find out the link percentage for each TC first */
  92         for (i = 0; i < MAX_TRAFFIC_CLASS; i++) {
  93                 p = &dcb_config->tc_config[i].path[direction];
  94                 bw_percent = dcb_config->bw_percentage[direction][p->bwg_id];
  95
  96                 link_percentage = p->bwg_percent;
  97                 /* Must be careful of integer division for very small nums */
  98                 link_percentage = (link_percentage * bw_percent) / 100;
  99                 if (p->bwg_percent > 0 && link_percentage == 0)
 100                         link_percentage = 1;
 101
 102                 /* Save link_percentage for reference */
 103                 p->link_percent = (u8)link_percentage;
 104
 105                 /* Calculate credit refill ratio using multiplier */
 106                 credit_refill = min(link_percentage * min_multiplier,
 107                                     MAX_CREDIT_REFILL);
 108                 p->data_credits_refill = (u16)credit_refill;
 109
 110                 /* Calculate maximum credit for the TC */
 111                 credit_max = (link_percentage * MAX_CREDIT) / 100;
 112
 113                 /*
 114                  * Adjustment based on rule checking, if the percentage
 115                  * of a TC is too small, the maximum credit may not be
 116                  * enough to send out a jumbo frame in data plane arbitration.
 117                  */
 118                 if (credit_max && (credit_max < min_credit))
 119                         credit_max = min_credit;
 120
 121                 if (direction == DCB_TX_CONFIG) {
 122                         /*
 123                          * Adjustment based on rule checking, if the
 124                          * percentage of a TC is too small, the maximum
 125                          * credit may not be enough to send out a TSO
 126                          * packet in descriptor plane arbitration.
 127                          */
 128                         if ((hw->mac.type == ixgbe_mac_82598EB) &&
 129                             credit_max &&
 130                             (credit_max < MINIMUM_CREDIT_FOR_TSO))
 131                                 credit_max = MINIMUM_CREDIT_FOR_TSO;
 132
 133                         dcb_config->tc_config[i].desc_credits_max =
 134                                 (u16)credit_max;
 135                 }
 136
 137                 p->data_credits_max = (u16)credit_max;
 138         }
 139
 140 out:
 141         return ret_val;
 142 }
 143
 144 /**
 145  * ixgbe_dcb_hw_config - Config and enable DCB
 146  * @hw: pointer to hardware structure
 147  * @dcb_config: pointer to ixgbe_dcb_config structure
 148  *
 149  * Configure dcb settings and enable dcb mode.
 150  */
 151 s32 ixgbe_dcb_hw_config(struct ixgbe_hw *hw,
 152                         struct ixgbe_dcb_config *dcb_config)
 153 {
 154         s32 ret = 0;
 155         switch (hw->mac.type) {
 156         case ixgbe_mac_82598EB:
 157                 ret = ixgbe_dcb_hw_config_82598(hw, dcb_config);
 158                 break;
 159         case ixgbe_mac_82599EB:
 160         case ixgbe_mac_X540:
 161                 ret = ixgbe_dcb_hw_config_82599(hw, dcb_config);
 162                 break;
 163         default:
 164                 break;
 165         }
 166         return ret;
 167 }
 168