drivers/net/ixgbe/ixgbe_dcb.c

/*******************************************************************************

  Intel 10 Gigabit PCI Express Linux driver
  Copyright(c) 1999 - 2010 Intel Corporation.

  This program is free software; you can redistribute it and/or modify it
  under the terms and conditions of the GNU General Public License,
  version 2, as published by the Free Software Foundation.

  This program is distributed in the hope it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  more details.

  You should have received a copy of the GNU General Public License along with
  this program; if not, write to the Free Software Foundation, Inc.,
  51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.

  The full GNU General Public License is included in this distribution in
  the file called "COPYING".

  Contact Information:
  Linux NICS <linux.nics@intel.com>
  e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
  Intel Corporation, 5200 N.E. Elam Young Parkway, Hillsboro, OR 97124-6497

*******************************************************************************/


#include "ixgbe.h"
#include "ixgbe_type.h"
#include "ixgbe_dcb.h"
#include "ixgbe_dcb_82598.h"
#include "ixgbe_dcb_82599.h"

/**
 * ixgbe_dcb_calculate_tc_credits - Calculates traffic class credits
 * @ixgbe_dcb_config: Struct containing DCB settings.
 * @direction: Configuring either Tx or Rx.
 *
 * This function calculates the credits allocated to each traffic class.
 * It should be called only after the rules are checked by
 * ixgbe_dcb_check_config().
 */
s32 ixgbe_dcb_calculate_tc_credits(struct ixgbe_dcb_config *dcb_config,
				   int max_frame, u8 direction)
{
	struct tc_bw_alloc *p;
	int min_credit;
	int min_multiplier;
	int min_percent = 100;
	s32 ret_val = 0;
	/* Initialization values default for Tx settings */
	u32 credit_refill       = 0;
	u32 credit_max          = 0;
	u16 link_percentage     = 0;
	u8  bw_percent          = 0;
	u8  i;

	if (dcb_config == NULL) {
		ret_val = DCB_ERR_CONFIG;
		goto out;
	}

	min_credit = ((max_frame / 2) + DCB_CREDIT_QUANTUM - 1) /
			DCB_CREDIT_QUANTUM;

	/* Find smallest link percentage */
	for (i = 0; i < MAX_TRAFFIC_CLASS; i++) {
		p = &dcb_config->tc_config[i].path[direction];
		bw_percent = dcb_config->bw_percentage[direction][p->bwg_id];
		link_percentage = p->bwg_percent;

		link_percentage = (link_percentage * bw_percent) / 100;

		if (link_percentage && link_percentage < min_percent)
			min_percent = link_percentage;
	}

	/*
	 * The ratio between traffic classes will control the bandwidth
	 * percentages seen on the wire. To calculate this ratio we use
	 * a multiplier. It is required that the refill credits must be
	 * larger than the max frame size so here we find the smallest
	 * multiplier that will allow all bandwidth percentages to be
	 * greater than the max frame size.
	 */
	min_multiplier = (min_credit / min_percent) + 1;

	/* Find out the link percentage for each TC first */
	for (i = 0; i < MAX_TRAFFIC_CLASS; i++) {
		p = &dcb_config->tc_config[i].path[direction];
		bw_percent = dcb_config->bw_percentage[direction][p->bwg_id];

		link_percentage = p->bwg_percent;
		/* Must be careful of integer division for very small nums */
		link_percentage = (link_percentage * bw_percent) / 100;
		if (p->bwg_percent > 0 && link_percentage == 0)
			link_percentage = 1;

		/* Save link_percentage for reference */
		p->link_percent = (u8)link_percentage;

		/* Calculate credit refill ratio using multiplier */
		credit_refill = min(link_percentage * min_multiplier,
				    MAX_CREDIT_REFILL);
		p->data_credits_refill = (u16)credit_refill;

		/* Calculate maximum credit for the TC */
		credit_max = (link_percentage * MAX_CREDIT) / 100;

		/*
		 * Adjustment based on rule checking, if the percentage
		 * of a TC is too small, the maximum credit may not be
		 * enough to send out a jumbo frame in data plane arbitration.
		 */
		if (credit_max && (credit_max < min_credit))
			credit_max = min_credit;

		if (direction == DCB_TX_CONFIG) {
			/*
			 * Adjustment based on rule checking, if the
			 * percentage of a TC is too small, the maximum
			 * credit may not be enough to send out a TSO
			 * packet in descriptor plane arbitration.
			 */
			if (credit_max &&
			    (credit_max < MINIMUM_CREDIT_FOR_TSO))
				credit_max = MINIMUM_CREDIT_FOR_TSO;

			dcb_config->tc_config[i].desc_credits_max =
				(u16)credit_max;
		}

		p->data_credits_max = (u16)credit_max;
	}

out:
	return ret_val;
}

/**
 * ixgbe_dcb_hw_config - Config and enable DCB
 * @hw: pointer to hardware structure
 * @dcb_config: pointer to ixgbe_dcb_config structure
 *
 * Configure dcb settings and enable dcb mode.
 */
s32 ixgbe_dcb_hw_config(struct ixgbe_hw *hw,
                        struct ixgbe_dcb_config *dcb_config)
{
	s32 ret = 0;
	if (hw->mac.type == ixgbe_mac_82598EB)
		ret = ixgbe_dcb_hw_config_82598(hw, dcb_config);
	else if (hw->mac.type == ixgbe_mac_82599EB)
		ret = ixgbe_dcb_hw_config_82599(hw, dcb_config);
	return ret;
}