linux/drivers/net/ethernet/intel/igc/igc_tsn.c

// SPDX-License-Identifier: GPL-2.0
/* Copyright (c)  2019 Intel Corporation */

#include "igc.h"
#include "igc_hw.h"
#include "igc_tsn.h"

static bool is_any_launchtime(struct igc_adapter *adapter)
{
	int i;

	for (i = 0; i < adapter->num_tx_queues; i++) {
		struct igc_ring *ring = adapter->tx_ring[i];

		if (ring->launchtime_enable)
			return true;
	}

	return false;
}

static bool is_cbs_enabled(struct igc_adapter *adapter)
{
	int i;

	for (i = 0; i < adapter->num_tx_queues; i++) {
		struct igc_ring *ring = adapter->tx_ring[i];

		if (ring->cbs_enable)
			return true;
	}

	return false;
}

static unsigned int igc_tsn_new_flags(struct igc_adapter *adapter)
{
	unsigned int new_flags = adapter->flags & ~IGC_FLAG_TSN_ANY_ENABLED;

	if (adapter->taprio_offload_enable)
		new_flags |= IGC_FLAG_TSN_QBV_ENABLED;

	if (is_any_launchtime(adapter))
		new_flags |= IGC_FLAG_TSN_QBV_ENABLED;

	if (is_cbs_enabled(adapter))
		new_flags |= IGC_FLAG_TSN_QAV_ENABLED;

	if (adapter->strict_priority_enable)
		new_flags |= IGC_FLAG_TSN_LEGACY_ENABLED;

	return new_flags;
}

static bool igc_tsn_is_tx_mode_in_tsn(struct igc_adapter *adapter)
{
	struct igc_hw *hw = &adapter->hw;

	return !!(rd32(IGC_TQAVCTRL) & IGC_TQAVCTRL_TRANSMIT_MODE_TSN);
}

void igc_tsn_adjust_txtime_offset(struct igc_adapter *adapter)
{
	struct igc_hw *hw = &adapter->hw;
	u16 txoffset;

	if (!igc_tsn_is_tx_mode_in_tsn(adapter))
		return;

	switch (adapter->link_speed) {
	case SPEED_10:
		txoffset = IGC_TXOFFSET_SPEED_10;
		break;
	case SPEED_100:
		txoffset = IGC_TXOFFSET_SPEED_100;
		break;
	case SPEED_1000:
		txoffset = IGC_TXOFFSET_SPEED_1000;
		break;
	case SPEED_2500:
		txoffset = IGC_TXOFFSET_SPEED_2500;
		break;
	default:
		txoffset = 0;
		break;
	}

	wr32(IGC_GTXOFFSET, txoffset);
}

static void igc_tsn_restore_retx_default(struct igc_adapter *adapter)
{
	struct igc_hw *hw = &adapter->hw;
	u32 retxctl;

	retxctl = rd32(IGC_RETX_CTL) & IGC_RETX_CTL_WATERMARK_MASK;
	wr32(IGC_RETX_CTL, retxctl);
}

bool igc_tsn_is_taprio_activated_by_user(struct igc_adapter *adapter)
{
	struct igc_hw *hw = &adapter->hw;

	return (rd32(IGC_BASET_H) || rd32(IGC_BASET_L)) &&
		adapter->taprio_offload_enable;
}

static void igc_tsn_tx_arb(struct igc_adapter *adapter, u16 *queue_per_tc)
{
	struct igc_hw *hw = &adapter->hw;
	u32 txarb;

	txarb = rd32(IGC_TXARB);

	txarb &= ~(IGC_TXARB_TXQ_PRIO_0_MASK |
		   IGC_TXARB_TXQ_PRIO_1_MASK |
		   IGC_TXARB_TXQ_PRIO_2_MASK |
		   IGC_TXARB_TXQ_PRIO_3_MASK);

	txarb |= IGC_TXARB_TXQ_PRIO_0(queue_per_tc[3]);
	txarb |= IGC_TXARB_TXQ_PRIO_1(queue_per_tc[2]);
	txarb |= IGC_TXARB_TXQ_PRIO_2(queue_per_tc[1]);
	txarb |= IGC_TXARB_TXQ_PRIO_3(queue_per_tc[0]);

	wr32(IGC_TXARB, txarb);
}

/* Returns the TSN specific registers to their default values after
 * the adapter is reset.
 */
static int igc_tsn_disable_offload(struct igc_adapter *adapter)
{
	u16 queue_per_tc[4] = { 3, 2, 1, 0 };
	struct igc_hw *hw = &adapter->hw;
	u32 tqavctrl;
	int i;

	wr32(IGC_GTXOFFSET, 0);
	wr32(IGC_TXPBS, I225_TXPBSIZE_DEFAULT);
	wr32(IGC_DTXMXPKTSZ, IGC_DTXMXPKTSZ_DEFAULT);

	if (igc_is_device_id_i226(hw))
		igc_tsn_restore_retx_default(adapter);

	tqavctrl = rd32(IGC_TQAVCTRL);
	tqavctrl &= ~(IGC_TQAVCTRL_TRANSMIT_MODE_TSN |
		      IGC_TQAVCTRL_ENHANCED_QAV | IGC_TQAVCTRL_FUTSCDDIS);

	wr32(IGC_TQAVCTRL, tqavctrl);

	for (i = 0; i < adapter->num_tx_queues; i++) {
		wr32(IGC_TXQCTL(i), 0);
		wr32(IGC_STQT(i), 0);
		wr32(IGC_ENDQT(i), NSEC_PER_SEC);
	}

	wr32(IGC_QBVCYCLET_S, 0);
	wr32(IGC_QBVCYCLET, NSEC_PER_SEC);

	/* Reset mqprio TC configuration. */
	netdev_reset_tc(adapter->netdev);

	/* Restore the default Tx arbitration: Priority 0 has the highest
	 * priority and is assigned to queue 0 and so on and so forth.
	 */
	igc_tsn_tx_arb(adapter, queue_per_tc);

	adapter->flags &= ~IGC_FLAG_TSN_QBV_ENABLED;
	adapter->flags &= ~IGC_FLAG_TSN_LEGACY_ENABLED;

	return 0;
}

/* To partially fix i226 HW errata, reduce MAC internal buffering from 192 Bytes
 * to 88 Bytes by setting RETX_CTL register using the recommendation from:
 * a) Ethernet Controller I225/I226 Specification Update Rev 2.1
 *    Item 9: TSN: Packet Transmission Might Cross the Qbv Window
 * b) I225/6 SW User Manual Rev 1.2.4: Section 8.11.5 Retry Buffer Control
 */
static void igc_tsn_set_retx_qbvfullthreshold(struct igc_adapter *adapter)
{
	struct igc_hw *hw = &adapter->hw;
	u32 retxctl, watermark;

	retxctl = rd32(IGC_RETX_CTL);
	watermark = retxctl & IGC_RETX_CTL_WATERMARK_MASK;
	/* Set QBVFULLTH value using watermark and set QBVFULLEN */
	retxctl |= (watermark << IGC_RETX_CTL_QBVFULLTH_SHIFT) |
		   IGC_RETX_CTL_QBVFULLEN;
	wr32(IGC_RETX_CTL, retxctl);
}

static int igc_tsn_enable_offload(struct igc_adapter *adapter)
{
	struct igc_hw *hw = &adapter->hw;
	u32 tqavctrl, baset_l, baset_h;
	u32 sec, nsec, cycle;
	ktime_t base_time, systim;
	int i;

	wr32(IGC_TSAUXC, 0);
	wr32(IGC_DTXMXPKTSZ, IGC_DTXMXPKTSZ_TSN);
	wr32(IGC_TXPBS, IGC_TXPBSIZE_TSN);

	if (igc_is_device_id_i226(hw))
		igc_tsn_set_retx_qbvfullthreshold(adapter);

	if (adapter->strict_priority_enable) {
		int err;

		err = netdev_set_num_tc(adapter->netdev, adapter->num_tc);
		if (err)
			return err;

		for (i = 0; i < adapter->num_tc; i++) {
			err = netdev_set_tc_queue(adapter->netdev, i, 1,
						  adapter->queue_per_tc[i]);
			if (err)
				return err;
		}

		/* In case the card is configured with less than four queues. */
		for (; i < IGC_MAX_TX_QUEUES; i++)
			adapter->queue_per_tc[i] = i;

		/* Configure queue priorities according to the user provided
		 * mapping.
		 */
		igc_tsn_tx_arb(adapter, adapter->queue_per_tc);

		/* Enable legacy TSN mode which will do strict priority without
		 * any other TSN features.
		 */
		tqavctrl = rd32(IGC_TQAVCTRL);
		tqavctrl |= IGC_TQAVCTRL_TRANSMIT_MODE_TSN;
		tqavctrl &= ~IGC_TQAVCTRL_ENHANCED_QAV;
		wr32(IGC_TQAVCTRL, tqavctrl);

		return 0;
	}

	for (i = 0; i < adapter->num_tx_queues; i++) {
		struct igc_ring *ring = adapter->tx_ring[i];
		u32 txqctl = 0;
		u16 cbs_value;
		u32 tqavcc;

		wr32(IGC_STQT(i), ring->start_time);
		wr32(IGC_ENDQT(i), ring->end_time);

		if (adapter->taprio_offload_enable) {
			/* If taprio_offload_enable is set we are in "taprio"
			 * mode and we need to be strict about the
			 * cycles: only transmit a packet if it can be
			 * completed during that cycle.
			 *
			 * If taprio_offload_enable is NOT true when
			 * enabling TSN offload, the cycle should have
			 * no external effects, but is only used internally
			 * to adapt the base time register after a second
			 * has passed.
			 *
			 * Enabling strict mode in this case would
			 * unnecessarily prevent the transmission of
			 * certain packets (i.e. at the boundary of a
			 * second) and thus interfere with the launchtime
			 * feature that promises transmission at a
			 * certain point in time.
			 */
			txqctl |= IGC_TXQCTL_STRICT_CYCLE |
				IGC_TXQCTL_STRICT_END;
		}

		if (ring->launchtime_enable)
			txqctl |= IGC_TXQCTL_QUEUE_MODE_LAUNCHT;

		/* Skip configuring CBS for Q2 and Q3 */
		if (i > 1)
			goto skip_cbs;

		if (ring->cbs_enable) {
			if (i == 0)
				txqctl |= IGC_TXQCTL_QAV_SEL_CBS0;
			else
				txqctl |= IGC_TXQCTL_QAV_SEL_CBS1;

			/* According to i225 datasheet section 7.5.2.7, we
			 * should set the 'idleSlope' field from TQAVCC
			 * register following the equation:
			 *
			 * value = link-speed   0x7736 * BW * 0.2
			 *         ---------- *  -----------------         (E1)
			 *          100Mbps            2.5
			 *
			 * Note that 'link-speed' is in Mbps.
			 *
			 * 'BW' is the percentage bandwidth out of full
			 * link speed which can be found with the
			 * following equation. Note that idleSlope here
			 * is the parameter from this function
			 * which is in kbps.
			 *
			 *     BW =     idleSlope
			 *          -----------------                      (E2)
			 *          link-speed * 1000
			 *
			 * That said, we can come up with a generic
			 * equation to calculate the value we should set
			 * it TQAVCC register by replacing 'BW' in E1 by E2.
			 * The resulting equation is:
			 *
			 * value = link-speed * 0x7736 * idleSlope * 0.2
			 *         -------------------------------------   (E3)
			 *             100 * 2.5 * link-speed * 1000
			 *
			 * 'link-speed' is present in both sides of the
			 * fraction so it is canceled out. The final
			 * equation is the following:
			 *
			 *     value = idleSlope * 61036
			 *             -----------------                   (E4)
			 *                  2500000
			 *
			 * NOTE: For i225, given the above, we can see
			 *       that idleslope is represented in
			 *       40.959433 kbps units by the value at
			 *       the TQAVCC register (2.5Gbps / 61036),
			 *       which reduces the granularity for
			 *       idleslope increments.
			 *
			 * In i225 controller, the sendSlope and loCredit
			 * parameters from CBS are not configurable
			 * by software so we don't do any
			 * 'controller configuration' in respect to
			 * these parameters.
			 */
			cbs_value = DIV_ROUND_UP_ULL(ring->idleslope
						     * 61036ULL, 2500000);

			tqavcc = rd32(IGC_TQAVCC(i));
			tqavcc &= ~IGC_TQAVCC_IDLESLOPE_MASK;
			tqavcc |= cbs_value | IGC_TQAVCC_KEEP_CREDITS;
			wr32(IGC_TQAVCC(i), tqavcc);

			wr32(IGC_TQAVHC(i),
			     0x80000000 + ring->hicredit * 0x7736);
		} else {
			/* Disable any CBS for the queue */
			txqctl &= ~(IGC_TXQCTL_QAV_SEL_MASK);

			/* Set idleSlope to zero. */
			tqavcc = rd32(IGC_TQAVCC(i));
			tqavcc &= ~(IGC_TQAVCC_IDLESLOPE_MASK |
				    IGC_TQAVCC_KEEP_CREDITS);
			wr32(IGC_TQAVCC(i), tqavcc);

			/* Set hiCredit to zero. */
			wr32(IGC_TQAVHC(i), 0);
		}
skip_cbs:
		wr32(IGC_TXQCTL(i), txqctl);
	}

	tqavctrl = rd32(IGC_TQAVCTRL) & ~IGC_TQAVCTRL_FUTSCDDIS;

	tqavctrl |= IGC_TQAVCTRL_TRANSMIT_MODE_TSN | IGC_TQAVCTRL_ENHANCED_QAV;

	adapter->qbv_count++;

	cycle = adapter->cycle_time;
	base_time = adapter->base_time;

	nsec = rd32(IGC_SYSTIML);
	sec = rd32(IGC_SYSTIMH);

	systim = ktime_set(sec, nsec);
	if (ktime_compare(systim, base_time) > 0) {
		s64 n = div64_s64(ktime_sub_ns(systim, base_time), cycle);

		base_time = ktime_add_ns(base_time, (n + 1) * cycle);
	} else {
		if (igc_is_device_id_i226(hw)) {
			ktime_t adjust_time, expires_time;

		       /* According to datasheet section 7.5.2.9.3.3, FutScdDis bit
			* has to be configured before the cycle time and base time.
			* Tx won't hang if a GCL is already running,
			* so in this case we don't need to set FutScdDis.
			*/
			if (!(rd32(IGC_BASET_H) || rd32(IGC_BASET_L)))
				tqavctrl |= IGC_TQAVCTRL_FUTSCDDIS;

			nsec = rd32(IGC_SYSTIML);
			sec = rd32(IGC_SYSTIMH);
			systim = ktime_set(sec, nsec);

			adjust_time = adapter->base_time;
			expires_time = ktime_sub_ns(adjust_time, systim);
			hrtimer_start(&adapter->hrtimer, expires_time, HRTIMER_MODE_REL);
		}
	}

	wr32(IGC_TQAVCTRL, tqavctrl);

	wr32(IGC_QBVCYCLET_S, cycle);
	wr32(IGC_QBVCYCLET, cycle);

	baset_h = div_s64_rem(base_time, NSEC_PER_SEC, &baset_l);
	wr32(IGC_BASET_H, baset_h);

	/* In i226, Future base time is only supported when FutScdDis bit
	 * is enabled and only active for re-configuration.
	 * In this case, initialize the base time with zero to create
	 * "re-configuration" scenario then only set the desired base time.
	 */
	if (tqavctrl & IGC_TQAVCTRL_FUTSCDDIS)
		wr32(IGC_BASET_L, 0);
	wr32(IGC_BASET_L, baset_l);

	return 0;
}

int igc_tsn_reset(struct igc_adapter *adapter)
{
	unsigned int new_flags;
	int err = 0;

	new_flags = igc_tsn_new_flags(adapter);

	if (!(new_flags & IGC_FLAG_TSN_ANY_ENABLED))
		return igc_tsn_disable_offload(adapter);

	err = igc_tsn_enable_offload(adapter);
	if (err < 0)
		return err;

	adapter->flags = new_flags;

	return err;
}

static bool igc_tsn_will_tx_mode_change(struct igc_adapter *adapter)
{
	bool any_tsn_enabled = !!(igc_tsn_new_flags(adapter) &
				  IGC_FLAG_TSN_ANY_ENABLED);

	return (any_tsn_enabled && !igc_tsn_is_tx_mode_in_tsn(adapter)) ||
	       (!any_tsn_enabled && igc_tsn_is_tx_mode_in_tsn(adapter));
}

int igc_tsn_offload_apply(struct igc_adapter *adapter)
{
	/* Per I225/6 HW Design Section 7.5.2.1 guideline, if tx mode change
	 * from legacy->tsn or tsn->legacy, then reset adapter is needed.
	 */
	if (netif_running(adapter->netdev) &&
	    igc_tsn_will_tx_mode_change(adapter)) {
		schedule_work(&adapter->reset_task);
		return 0;
	}

	igc_tsn_reset(adapter);

	return 0;
}