bnxt_en: add support for software dynamic interrupt moderation

This implements the changes needed for the bnxt_en driver to add support
for dynamic interrupt moderation per ring.

This does add additional counters in the receive path, but testing shows
that any additional instructions are offset by throughput gain when the
default configuration is for low latency.

Signed-off-by: Andy Gospodarek <gospo@broadcom.com>
Acked-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: CCX-Stingray

drivers/net/ethernet/broadcom/bnxt/Makefile

@@ -1,4 +1,4 @@
 obj-$(CONFIG_BNXT) += bnxt_en.o
 
-bnxt_en-y := bnxt.o bnxt_sriov.o bnxt_ethtool.o bnxt_dcb.o bnxt_ulp.o bnxt_xdp.o bnxt_vfr.o bnxt_devlink.o
+bnxt_en-y := bnxt.o bnxt_sriov.o bnxt_ethtool.o bnxt_dcb.o bnxt_ulp.o bnxt_xdp.o bnxt_vfr.o bnxt_devlink.o bnxt_dim.o
 bnxt_en-$(CONFIG_BNXT_FLOWER_OFFLOAD) += bnxt_tc.o

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -1645,6 +1645,8 @@ static int bnxt_rx_pkt(struct bnxt *bp, struct bnxt_napi *bnapi, u32 *raw_cons,
 	rxr->rx_next_cons = NEXT_RX(cons);
 
 next_rx_no_prod:
+	cpr->rx_packets += 1;
+	cpr->rx_bytes += len;
 	*raw_cons = tmp_raw_cons;
 
 	return rc;
@@ -1802,6 +1804,7 @@ static irqreturn_t bnxt_msix(int irq, void *dev_instance)
 	struct bnxt_cp_ring_info *cpr = &bnapi->cp_ring;
 	u32 cons = RING_CMP(cpr->cp_raw_cons);
 
+	cpr->event_ctr++;
 	prefetch(&cpr->cp_desc_ring[CP_RING(cons)][CP_IDX(cons)]);
 	napi_schedule(&bnapi->napi);
 	return IRQ_HANDLED;
@@ -2025,6 +2028,15 @@ static int bnxt_poll(struct napi_struct *napi, int budget)
 			break;
 		}
 	}
+	if (bp->flags & BNXT_FLAG_DIM) {
+		struct net_dim_sample dim_sample;
+
+		net_dim_sample(cpr->event_ctr,
+			       cpr->rx_packets,
+			       cpr->rx_bytes,
+			       &dim_sample);
+		net_dim(&cpr->dim, dim_sample);
+	}
 	mmiowb();
 	return work_done;
 }
@@ -2617,6 +2629,8 @@ static void bnxt_init_cp_rings(struct bnxt *bp)
 		struct bnxt_ring_struct *ring = &cpr->cp_ring_struct;
 
 		ring->fw_ring_id = INVALID_HW_RING_ID;
+		cpr->rx_ring_coal.coal_ticks = bp->rx_coal.coal_ticks;
+		cpr->rx_ring_coal.coal_bufs = bp->rx_coal.coal_bufs;
 	}
 }
 
@@ -4593,6 +4607,36 @@ static void bnxt_hwrm_set_coal_params(struct bnxt_coal *hw_coal,
 	req->flags = cpu_to_le16(flags);
 }
 
+int bnxt_hwrm_set_ring_coal(struct bnxt *bp, struct bnxt_napi *bnapi)
+{
+	struct hwrm_ring_cmpl_ring_cfg_aggint_params_input req_rx = {0};
+	struct bnxt_cp_ring_info *cpr = &bnapi->cp_ring;
+	struct bnxt_coal coal;
+	unsigned int grp_idx;
+
+	/* Tick values in micro seconds.
+	 * 1 coal_buf x bufs_per_record = 1 completion record.
+	 */
+	memcpy(&coal, &bp->rx_coal, sizeof(struct bnxt_coal));
+
+	coal.coal_ticks = cpr->rx_ring_coal.coal_ticks;
+	coal.coal_bufs = cpr->rx_ring_coal.coal_bufs;
+
+	if (!bnapi->rx_ring)
+		return -ENODEV;
+
+	bnxt_hwrm_cmd_hdr_init(bp, &req_rx,
+			       HWRM_RING_CMPL_RING_CFG_AGGINT_PARAMS, -1, -1);
+
+	bnxt_hwrm_set_coal_params(&coal, &req_rx);
+
+	grp_idx = bnapi->index;
+	req_rx.ring_id = cpu_to_le16(bp->grp_info[grp_idx].cp_fw_ring_id);
+
+	return hwrm_send_message(bp, &req_rx, sizeof(req_rx),
+				 HWRM_CMD_TIMEOUT);
+}
+
 int bnxt_hwrm_set_coal(struct bnxt *bp)
 {
 	int i, rc = 0;
@@ -5715,7 +5759,13 @@ static void bnxt_enable_napi(struct bnxt *bp)
 	int i;
 
 	for (i = 0; i < bp->cp_nr_rings; i++) {
+		struct bnxt_cp_ring_info *cpr = &bp->bnapi[i]->cp_ring;
 		bp->bnapi[i]->in_reset = false;
+
+		if (bp->bnapi[i]->rx_ring) {
+			INIT_WORK(&cpr->dim.work, bnxt_dim_work);
+			cpr->dim.mode = NET_DIM_CQ_PERIOD_MODE_START_FROM_EQE;
+		}
 		napi_enable(&bp->bnapi[i]->napi);
 	}
 }

drivers/net/ethernet/broadcom/bnxt/bnxt.h

@@ -24,6 +24,7 @@
 #include <net/dst_metadata.h>
 #include <net/switchdev.h>
 #include <net/xdp.h>
+#include <linux/net_dim.h>
 
 struct tx_bd {
 	__le32 tx_bd_len_flags_type;
@@ -608,6 +609,17 @@ struct bnxt_tx_ring_info {
 	struct bnxt_ring_struct	tx_ring_struct;
 };
 
+struct bnxt_coal {
+	u16			coal_ticks;
+	u16			coal_ticks_irq;
+	u16			coal_bufs;
+	u16			coal_bufs_irq;
+			/* RING_IDLE enabled when coal ticks < idle_thresh  */
+	u16			idle_thresh;
+	u8			bufs_per_record;
+	u8			budget;
+};
+
 struct bnxt_tpa_info {
 	void			*data;
 	u8			*data_ptr;
@@ -672,6 +684,13 @@ struct bnxt_cp_ring_info {
 	u32			cp_raw_cons;
 	void __iomem		*cp_doorbell;
 
+	struct bnxt_coal	rx_ring_coal;
+	u64			rx_packets;
+	u64			rx_bytes;
+	u64			event_ctr;
+
+	struct net_dim		dim;
+
 	struct tx_cmp		*cp_desc_ring[MAX_CP_PAGES];
 
 	dma_addr_t		cp_desc_mapping[MAX_CP_PAGES];
@@ -946,17 +965,6 @@ struct bnxt_test_info {
 #define BNXT_CAG_REG_LEGACY_INT_STATUS	0x4014
 #define BNXT_CAG_REG_BASE		0x300000
 
-struct bnxt_coal {
-	u16			coal_ticks;
-	u16			coal_ticks_irq;
-	u16			coal_bufs;
-	u16			coal_bufs_irq;
-			/* RING_IDLE enabled when coal ticks < idle_thresh  */
-	u16			idle_thresh;
-	u8			bufs_per_record;
-	u8			budget;
-};
-
 struct bnxt_tc_flow_stats {
 	u64		packets;
 	u64		bytes;
@@ -1128,6 +1136,7 @@ struct bnxt {
 	#define BNXT_FLAG_DOUBLE_DB	0x400000
 	#define BNXT_FLAG_FW_DCBX_AGENT	0x800000
 	#define BNXT_FLAG_CHIP_NITRO_A0	0x1000000
+	#define BNXT_FLAG_DIM		0x2000000
 
 	#define BNXT_FLAG_ALL_CONFIG_FEATS (BNXT_FLAG_TPA |		\
 					    BNXT_FLAG_RFS |		\
@@ -1425,4 +1434,7 @@ int bnxt_setup_mq_tc(struct net_device *dev, u8 tc);
 int bnxt_get_max_rings(struct bnxt *, int *, int *, bool);
 void bnxt_restore_pf_fw_resources(struct bnxt *bp);
 int bnxt_port_attr_get(struct bnxt *bp, struct switchdev_attr *attr);
+void bnxt_dim_work(struct work_struct *work);
+int bnxt_hwrm_set_ring_coal(struct bnxt *bp, struct bnxt_napi *bnapi);
+
 #endif

drivers/net/ethernet/broadcom/bnxt/bnxt_dim.c

@@ -0,0 +1,32 @@
+/* Broadcom NetXtreme-C/E network driver.
+ *
+ * Copyright (c) 2017-2018 Broadcom Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/net_dim.h>
+#include "bnxt_hsi.h"
+#include "bnxt.h"
+
+void bnxt_dim_work(struct work_struct *work)
+{
+	struct net_dim *dim = container_of(work, struct net_dim,
+					   work);
+	struct bnxt_cp_ring_info *cpr = container_of(dim,
+						     struct bnxt_cp_ring_info,
+						     dim);
+	struct bnxt_napi *bnapi = container_of(cpr,
+					       struct bnxt_napi,
+					       cp_ring);
+	struct net_dim_cq_moder cur_profile = net_dim_get_profile(dim->mode,
+								  dim->profile_ix);
+
+	cpr->rx_ring_coal.coal_ticks = cur_profile.usec;
+	cpr->rx_ring_coal.coal_bufs = cur_profile.pkts;
+
+	bnxt_hwrm_set_ring_coal(bnapi->bp, bnapi);
+	dim->state = NET_DIM_START_MEASURE;
+}

drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c

@@ -49,6 +49,8 @@ static int bnxt_get_coalesce(struct net_device *dev,
 
 	memset(coal, 0, sizeof(*coal));
 
+	coal->use_adaptive_rx_coalesce = bp->flags & BNXT_FLAG_DIM;
+
 	hw_coal = &bp->rx_coal;
 	mult = hw_coal->bufs_per_record;
 	coal->rx_coalesce_usecs = hw_coal->coal_ticks;
@@ -77,6 +79,15 @@ static int bnxt_set_coalesce(struct net_device *dev,
 	int rc = 0;
 	u16 mult;
 
+	if (coal->use_adaptive_rx_coalesce) {
+		bp->flags |= BNXT_FLAG_DIM;
+	} else {
+		if (bp->flags & BNXT_FLAG_DIM) {
+			bp->flags &= ~(BNXT_FLAG_DIM);
+			goto reset_coalesce;
+		}
+	}
+
 	hw_coal = &bp->rx_coal;
 	mult = hw_coal->bufs_per_record;
 	hw_coal->coal_ticks = coal->rx_coalesce_usecs;
@@ -104,6 +115,7 @@ static int bnxt_set_coalesce(struct net_device *dev,
 		update_stats = true;
 	}
 
+reset_coalesce:
 	if (netif_running(dev)) {
 		if (update_stats) {
 			rc = bnxt_close_nic(bp, true, false);