gve: DQO: Configure interrupts on device up

When interrupts are first enabled, we also set the ratelimits, which
will be static for the entire usage of the device.
Signed-off-by: Bailey Forrest <bcf@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Catherine Sullivan <csully@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/google/gve/gve_dqo.h

@@ -13,6 +13,9 @@
 #define GVE_ITR_CLEAR_PBA_BIT_DQO BIT(1)
 #define GVE_ITR_NO_UPDATE_DQO (3 << 3)
 
+#define GVE_ITR_INTERVAL_DQO_SHIFT 5
+#define GVE_ITR_INTERVAL_DQO_MASK ((1 << 12) - 1)
+
 #define GVE_TX_IRQ_RATELIMIT_US_DQO 50
 #define GVE_RX_IRQ_RATELIMIT_US_DQO 20
 
@@ -38,6 +41,22 @@ gve_tx_put_doorbell_dqo(const struct gve_priv *priv,
 	iowrite32(val, &priv->db_bar2[index]);
 }
 
+/* Builds register value to write to DQO IRQ doorbell to enable with specified
+ * ratelimit.
+ */
+static inline u32 gve_set_itr_ratelimit_dqo(u32 ratelimit_us)
+{
+	u32 result = GVE_ITR_ENABLE_BIT_DQO;
+
+	/* Interval has 2us granularity. */
+	ratelimit_us >>= 1;
+
+	ratelimit_us &= GVE_ITR_INTERVAL_DQO_MASK;
+	result |= (ratelimit_us << GVE_ITR_INTERVAL_DQO_SHIFT);
+
+	return result;
+}
+
 static inline void
 gve_write_irq_doorbell_dqo(const struct gve_priv *priv,
 			   const struct gve_notify_block *block, u32 val)

drivers/net/ethernet/google/gve/gve_main.c

@@ -1077,14 +1077,26 @@ static void gve_turnup(struct gve_priv *priv)
 		struct gve_notify_block *block = &priv->ntfy_blocks[ntfy_idx];
 
 		napi_enable(&block->napi);
-		iowrite32be(0, gve_irq_doorbell(priv, block));
+		if (gve_is_gqi(priv)) {
+			iowrite32be(0, gve_irq_doorbell(priv, block));
+		} else {
+			u32 val = gve_set_itr_ratelimit_dqo(GVE_TX_IRQ_RATELIMIT_US_DQO);
+
+			gve_write_irq_doorbell_dqo(priv, block, val);
+		}
 	}
 	for (idx = 0; idx < priv->rx_cfg.num_queues; idx++) {
 		int ntfy_idx = gve_rx_idx_to_ntfy(priv, idx);
 		struct gve_notify_block *block = &priv->ntfy_blocks[ntfy_idx];
 
 		napi_enable(&block->napi);
-		iowrite32be(0, gve_irq_doorbell(priv, block));
+		if (gve_is_gqi(priv)) {
+			iowrite32be(0, gve_irq_doorbell(priv, block));
+		} else {
+			u32 val = gve_set_itr_ratelimit_dqo(GVE_RX_IRQ_RATELIMIT_US_DQO);
+
+			gve_write_irq_doorbell_dqo(priv, block, val);
+		}
 	}
 
 	gve_set_napi_enabled(priv);