cxgb4: Add support for adaptive rx

Based on original work by Kumar Sanghvi <kumaras@chelsio.com>

Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4.h

@@ -452,6 +452,7 @@ struct sge_rspq {                   /* state for an SGE response queue */
 	u8 gen;                     /* current generation bit */
 	u8 intr_params;             /* interrupt holdoff parameters */
 	u8 next_intr_params;        /* holdoff params for next interrupt */
+	u8 adaptive_rx;
 	u8 pktcnt_idx;              /* interrupt packet threshold */
 	u8 uld;                     /* ULD handling this queue */
 	u8 idx;                     /* queue index within its group */

drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c

@@ -2753,8 +2753,31 @@ static int set_rx_intr_params(struct net_device *dev,
 	return 0;
 }
 
+static int set_adaptive_rx_setting(struct net_device *dev, int adaptive_rx)
+{
+	int i;
+	struct port_info *pi = netdev_priv(dev);
+	struct adapter *adap = pi->adapter;
+	struct sge_eth_rxq *q = &adap->sge.ethrxq[pi->first_qset];
+
+	for (i = 0; i < pi->nqsets; i++, q++)
+		q->rspq.adaptive_rx = adaptive_rx;
+
+	return 0;
+}
+
+static int get_adaptive_rx_setting(struct net_device *dev)
+{
+	struct port_info *pi = netdev_priv(dev);
+	struct adapter *adap = pi->adapter;
+	struct sge_eth_rxq *q = &adap->sge.ethrxq[pi->first_qset];
+
+	return q->rspq.adaptive_rx;
+}
+
 static int set_coalesce(struct net_device *dev, struct ethtool_coalesce *c)
 {
+	set_adaptive_rx_setting(dev, c->use_adaptive_rx_coalesce);
 	return set_rx_intr_params(dev, c->rx_coalesce_usecs,
 				  c->rx_max_coalesced_frames);
 }
@@ -2768,6 +2791,7 @@ static int get_coalesce(struct net_device *dev, struct ethtool_coalesce *c)
 	c->rx_coalesce_usecs = qtimer_val(adap, rq);
 	c->rx_max_coalesced_frames = (rq->intr_params & QINTR_CNT_EN) ?
 		adap->sge.counter_val[rq->pktcnt_idx] : 0;
+	c->use_adaptive_rx_coalesce = get_adaptive_rx_setting(dev);
 	return 0;
 }
 

drivers/net/ethernet/chelsio/cxgb4/sge.c

@@ -203,6 +203,9 @@ enum {
 	RX_LARGE_MTU_BUF = 0x3,   /* large MTU buffer */
 };
 
+static int timer_pkt_quota[] = {1, 1, 2, 3, 4, 5};
+#define MIN_NAPI_WORK  1
+
 static inline dma_addr_t get_buf_addr(const struct rx_sw_desc *d)
 {
 	return d->dma_addr & ~(dma_addr_t)RX_BUF_FLAGS;
@@ -1969,9 +1972,26 @@ static int napi_rx_handler(struct napi_struct *napi, int budget)
 	u32 val;
 
 	if (likely(work_done < budget)) {
+		int timer_index;
+
 		napi_complete(napi);
-		params = q->next_intr_params;
-		q->next_intr_params = q->intr_params;
+		timer_index = QINTR_TIMER_IDX_GET(q->next_intr_params);
+
+		if (q->adaptive_rx) {
+			if (work_done > max(timer_pkt_quota[timer_index],
+					    MIN_NAPI_WORK))
+				timer_index = (timer_index + 1);
+			else
+				timer_index = timer_index - 1;
+
+			timer_index = clamp(timer_index, 0, SGE_TIMERREGS - 1);
+			q->next_intr_params = QINTR_TIMER_IDX(timer_index) |
+							      V_QINTR_CNT_EN;
+			params = q->next_intr_params;
+		} else {
+			params = q->next_intr_params;
+			q->next_intr_params = q->intr_params;
+		}
 	} else
 		params = QINTR_TIMER_IDX(7);
 

drivers/net/ethernet/chelsio/cxgb4/t4_hw.h

@@ -135,6 +135,7 @@ struct rsp_ctrl {
 #define RSPD_GEN(x)  ((x) >> 7)
 #define RSPD_TYPE(x) (((x) >> 4) & 3)
 
+#define V_QINTR_CNT_EN	   0x0
 #define QINTR_CNT_EN       0x1
 #define QINTR_TIMER_IDX(x) ((x) << 1)
 #define QINTR_TIMER_IDX_GET(x) (((x) >> 1) & 0x7)

drivers/net/ethernet/chelsio/cxgb4/t4_regs.h

@@ -77,6 +77,7 @@
 #define  PIDX_T5(x)  (((x) >> S_PIDX_T5) & M_PIDX_T5)
 
 
+#define SGE_TIMERREGS	6
 #define SGE_PF_GTS 0x4
 #define  INGRESSQID_MASK   0xffff0000U
 #define  INGRESSQID_SHIFT  16