net: atlantic: QoS implementation: min_rate

This patch adds support for mqprio min_rate limiters.

A2 HW supports Weighted Strict Priority (WSP) arbitration for Tx Descriptor
Queue scheduling among TCs, which can be used for min_rate shaping.

Signed-off-by: Mark Starovoytov <mstarovoitov@marvell.com>
Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/aquantia/atlantic/aq_hw.h

@@ -280,6 +280,8 @@ struct aq_hw_ops {
 	int (*hw_rss_hash_set)(struct aq_hw_s *self,
 			       struct aq_rss_parameters *rss_params);
 
+	int (*hw_tc_rate_limit_set)(struct aq_hw_s *self);
+
 	int (*hw_get_regs)(struct aq_hw_s *self,
 			   const struct aq_hw_caps_s *aq_hw_caps,
 			   u32 *regs_buff);

drivers/net/ethernet/aquantia/atlantic/aq_main.c

@@ -340,7 +340,6 @@ static int aq_validate_mqprio_opt(struct aq_nic_s *self,
 	struct aq_nic_cfg_s *aq_nic_cfg = aq_nic_get_cfg(self);
 	const unsigned int tcs_max = min_t(u8, aq_nic_cfg->aq_hw_caps->tcs_max,
 					   AQ_CFG_TCS_MAX);
-	int i;
 
 	if (num_tc > tcs_max) {
 		netdev_err(self->ndev, "Too many TCs requested\n");
@@ -352,12 +351,9 @@ static int aq_validate_mqprio_opt(struct aq_nic_s *self,
 		return -EOPNOTSUPP;
 	}
 
-	for (i = 0; i < num_tc; i++) {
-		if (has_min_rate && mqprio->min_rate[i]) {
-			netdev_err(self->ndev,
-				   "Min tx rate is not supported\n");
-			return -EOPNOTSUPP;
-		}
+	if (has_min_rate && !ATL_HW_IS_CHIP_FEATURE(self->aq_hw, ANTIGUA)) {
+		netdev_err(self->ndev, "Min tx rate is not supported\n");
+		return -EOPNOTSUPP;
 	}
 
 	return 0;
@@ -368,23 +364,35 @@ static int aq_ndo_setup_tc(struct net_device *dev, enum tc_setup_type type,
 {
 	struct tc_mqprio_qopt_offload *mqprio = type_data;
 	struct aq_nic_s *aq_nic = netdev_priv(dev);
+	bool has_min_rate;
+	bool has_max_rate;
 	int err;
 	int i;
 
 	if (type != TC_SETUP_QDISC_MQPRIO)
 		return -EOPNOTSUPP;
 
+	has_min_rate = !!(mqprio->flags & TC_MQPRIO_F_MIN_RATE);
+	has_max_rate = !!(mqprio->flags & TC_MQPRIO_F_MAX_RATE);
+
 	err = aq_validate_mqprio_opt(aq_nic, mqprio, mqprio->qopt.num_tc);
 	if (err)
 		return err;
 
-	if (mqprio->flags & TC_MQPRIO_F_MAX_RATE) {
-		for (i = 0; i < mqprio->qopt.num_tc; i++) {
+	for (i = 0; i < mqprio->qopt.num_tc; i++) {
+		if (has_max_rate) {
 			u64 max_rate = mqprio->max_rate[i];
 
 			do_div(max_rate, AQ_MBPS_DIVISOR);
 			aq_nic_setup_tc_max_rate(aq_nic, i, (u32)max_rate);
 		}
+
+		if (has_min_rate) {
+			u64 min_rate = mqprio->min_rate[i];
+
+			do_div(min_rate, AQ_MBPS_DIVISOR);
+			aq_nic_setup_tc_min_rate(aq_nic, i, (u32)min_rate);
+		}
 	}
 
 	return aq_nic_setup_tc_mqprio(aq_nic, mqprio->qopt.num_tc,

drivers/net/ethernet/aquantia/atlantic/aq_nic.c

@@ -196,6 +196,9 @@ static int aq_nic_update_link_status(struct aq_nic_s *self)
 #if IS_ENABLED(CONFIG_MACSEC)
 		aq_macsec_enable(self);
 #endif
+		if (self->aq_hw_ops->hw_tc_rate_limit_set)
+			self->aq_hw_ops->hw_tc_rate_limit_set(self->aq_hw);
+
 		netif_tx_wake_all_queues(self->ndev);
 	}
 	if (netif_carrier_ok(self->ndev) && !self->link_status.mbps) {
@@ -1374,3 +1377,28 @@ int aq_nic_setup_tc_max_rate(struct aq_nic_s *self, const unsigned int tc,
 
 	return 0;
 }
+
+int aq_nic_setup_tc_min_rate(struct aq_nic_s *self, const unsigned int tc,
+			     const u32 min_rate)
+{
+	struct aq_nic_cfg_s *cfg = &self->aq_nic_cfg;
+
+	if (tc >= AQ_CFG_TCS_MAX)
+		return -EINVAL;
+
+	if (min_rate)
+		set_bit(tc, &cfg->tc_min_rate_msk);
+	else
+		clear_bit(tc, &cfg->tc_min_rate_msk);
+
+	if (min_rate && min_rate < 20) {
+		netdev_warn(self->ndev,
+			"Setting %s to the minimum usable value of %dMbps.\n",
+			"min rate", 20);
+		cfg->tc_min_rate[tc] = 20;
+	} else {
+		cfg->tc_min_rate[tc] = min_rate;
+	}
+
+	return 0;
+}

drivers/net/ethernet/aquantia/atlantic/aq_nic.h

@@ -66,6 +66,8 @@ struct aq_nic_cfg_s {
 	u8  tcs;
 	u8 prio_tc_map[8];
 	u32 tc_max_rate[AQ_CFG_TCS_MAX];
+	unsigned long tc_min_rate_msk;
+	u32 tc_min_rate[AQ_CFG_TCS_MAX];
 	struct aq_rss_parameters aq_rss;
 	u32 eee_speeds;
 };
@@ -198,4 +200,6 @@ void aq_nic_release_filter(struct aq_nic_s *self, enum aq_rx_filter_type type,
 int aq_nic_setup_tc_mqprio(struct aq_nic_s *self, u32 tcs, u8 *prio_tc_map);
 int aq_nic_setup_tc_max_rate(struct aq_nic_s *self, const unsigned int tc,
 			     const u32 max_rate);
+int aq_nic_setup_tc_min_rate(struct aq_nic_s *self, const unsigned int tc,
+			     const u32 min_rate);
 #endif /* AQ_NIC_H */

drivers/net/ethernet/aquantia/atlantic/hw_atl/hw_atl_b0.c

@@ -138,8 +138,6 @@ static int hw_atl_b0_hw_qos_set(struct aq_hw_s *self)
 	unsigned int prio = 0U;
 	u32 tc = 0U;
 
-	hw_atl_b0_hw_init_tx_tc_rate_limit(self);
-
 	if (cfg->is_ptp) {
 		tx_buff_size -= HW_ATL_B0_PTP_TXBUF_SIZE;
 		rx_buff_size -= HW_ATL_B0_PTP_RXBUF_SIZE;
@@ -152,18 +150,11 @@ static int hw_atl_b0_hw_qos_set(struct aq_hw_s *self)
 	/* TPS VM init */
 	hw_atl_tps_tx_pkt_shed_desc_vm_arb_mode_set(self, 0U);
 
-	/* TPS TC credits init */
-	hw_atl_tps_tx_pkt_shed_data_arb_mode_set(self, 0U);
-
 	tx_buff_size /= cfg->tcs;
 	rx_buff_size /= cfg->tcs;
 	for (tc = 0; tc < cfg->tcs; tc++) {
 		u32 threshold = 0U;
 
-		/* TX Packet Scheduler Data TC0 */
-		hw_atl_tps_tx_pkt_shed_tc_data_max_credit_set(self, tc, 0xFFF);
-		hw_atl_tps_tx_pkt_shed_tc_data_weight_set(self, tc, 0x64);
-
 		/* Tx buf size TC0 */
 		hw_atl_tpb_tx_pkt_buff_size_per_tc_set(self, tx_buff_size, tc);
 
@@ -319,24 +310,87 @@ int hw_atl_b0_hw_offload_set(struct aq_hw_s *self,
 	return aq_hw_err_from_flags(self);
 }
 
-int hw_atl_b0_hw_init_tx_tc_rate_limit(struct aq_hw_s *self)
+static int hw_atl_b0_hw_init_tx_tc_rate_limit(struct aq_hw_s *self)
 {
+	static const u32 max_weight = BIT(HW_ATL_TPS_DATA_TCTWEIGHT_WIDTH) - 1;
 	/* Scale factor is based on the number of bits in fractional portion */
 	static const u32 scale = BIT(HW_ATL_TPS_DESC_RATE_Y_WIDTH);
 	static const u32 frac_msk = HW_ATL_TPS_DESC_RATE_Y_MSK >>
 				    HW_ATL_TPS_DESC_RATE_Y_SHIFT;
+	const u32 link_speed = self->aq_link_status.mbps;
 	struct aq_nic_cfg_s *nic_cfg = self->aq_nic_cfg;
+	unsigned long num_min_rated_tcs = 0;
+	u32 tc_weight[AQ_CFG_TCS_MAX];
+	u32 fixed_max_credit;
+	u8 min_rate_msk = 0;
+	u32 sum_weight = 0;
 	int tc;
 
+	/* By default max_credit is based upon MTU (in unit of 64b) */
+	fixed_max_credit = nic_cfg->aq_hw_caps->mtu / 64;
+
+	if (link_speed) {
+		min_rate_msk = nic_cfg->tc_min_rate_msk &
+			       (BIT(nic_cfg->tcs) - 1);
+		num_min_rated_tcs = hweight8(min_rate_msk);
+	}
+
+	/* First, calculate weights where min_rate is specified */
+	if (num_min_rated_tcs) {
+		for (tc = 0; tc != nic_cfg->tcs; tc++) {
+			if (!nic_cfg->tc_min_rate[tc]) {
+				tc_weight[tc] = 0;
+				continue;
+			}
+
+			tc_weight[tc] = (-1L + link_speed +
+					 nic_cfg->tc_min_rate[tc] *
+					 max_weight) /
+					link_speed;
+			tc_weight[tc] = min(tc_weight[tc], max_weight);
+			sum_weight += tc_weight[tc];
+		}
+	}
+
+	/* WSP, if min_rate is set for at least one TC.
+	 * RR otherwise.
+	 */
+	hw_atl_tps_tx_pkt_shed_data_arb_mode_set(self, min_rate_msk ? 1U : 0U);
+	/* Data TC Arbiter takes precedence over Descriptor TC Arbiter,
+	 * leave Descriptor TC Arbiter as RR.
+	 */
 	hw_atl_tps_tx_pkt_shed_desc_tc_arb_mode_set(self, 0U);
+
 	hw_atl_tps_tx_desc_rate_mode_set(self, nic_cfg->is_qos ? 1U : 0U);
+
 	for (tc = 0; tc != nic_cfg->tcs; tc++) {
 		const u32 en = (nic_cfg->tc_max_rate[tc] != 0) ? 1U : 0U;
 		const u32 desc = AQ_NIC_CFG_TCVEC2RING(nic_cfg, tc, 0);
+		u32 weight, max_credit;
 
-		hw_atl_tps_tx_pkt_shed_desc_tc_max_credit_set(self, tc, 0x50);
+		hw_atl_tps_tx_pkt_shed_desc_tc_max_credit_set(self, tc,
+							      fixed_max_credit);
 		hw_atl_tps_tx_pkt_shed_desc_tc_weight_set(self, tc, 0x1E);
 
+		if (num_min_rated_tcs) {
+			weight = tc_weight[tc];
+
+			if (!weight && sum_weight < max_weight)
+				weight = (max_weight - sum_weight) /
+					 (nic_cfg->tcs - num_min_rated_tcs);
+			else if (!weight)
+				weight = 0x64;
+
+			max_credit = max(8 * weight, fixed_max_credit);
+		} else {
+			weight = 0x64;
+			max_credit = 0xFFF;
+		}
+
+		hw_atl_tps_tx_pkt_shed_tc_data_weight_set(self, tc, weight);
+		hw_atl_tps_tx_pkt_shed_tc_data_max_credit_set(self, tc,
+							      max_credit);
+
 		hw_atl_tps_tx_desc_rate_en_set(self, desc, en);
 
 		if (en) {
@@ -1550,6 +1604,7 @@ const struct aq_hw_ops hw_atl_ops_b0 = {
 	.hw_interrupt_moderation_set = hw_atl_b0_hw_interrupt_moderation_set,
 	.hw_rss_set                  = hw_atl_b0_hw_rss_set,
 	.hw_rss_hash_set             = hw_atl_b0_hw_rss_hash_set,
+	.hw_tc_rate_limit_set        = hw_atl_b0_hw_init_tx_tc_rate_limit,
 	.hw_get_regs                 = hw_atl_utils_hw_get_regs,
 	.hw_get_hw_stats             = hw_atl_utils_get_hw_stats,
 	.hw_get_fw_version           = hw_atl_utils_get_fw_version,

drivers/net/ethernet/aquantia/atlantic/hw_atl/hw_atl_b0.h

@@ -62,8 +62,6 @@ int hw_atl_b0_hw_mac_addr_set(struct aq_hw_s *self, u8 *mac_addr);
 
 int hw_atl_b0_hw_start(struct aq_hw_s *self);
 
-int hw_atl_b0_hw_init_tx_tc_rate_limit(struct aq_hw_s *self);
-
 int hw_atl_b0_hw_irq_enable(struct aq_hw_s *self, u64 mask);
 int hw_atl_b0_hw_irq_disable(struct aq_hw_s *self, u64 mask);
 int hw_atl_b0_hw_irq_read(struct aq_hw_s *self, u64 *mask);