dpaa2-eth: Add pause frame support

Starting with firmware version MC10.18.0, we have support for
L2 flow control. Asymmetrical configuration (Rx or Tx only) is
supported, but not pause frame autonegotioation.

Pause frame configuration is done via ethtool. By default, we start
with flow control enabled on both Rx and Tx. Changes are propagated
to hardware through firmware commands, using two flags (PAUSE,
ASYM_PAUSE) to specify Rx and Tx pause configuration, as follows:

PAUSE | ASYM_PAUSE | Rx pause | Tx pause
----------------------------------------
  0   |     0      | disabled | disabled
  0   |     1      | disabled | enabled
  1   |     0      | enabled  | enabled
  1   |     1      | enabled  | disabled

The hardware can automatically send pause frames when the number
of buffers in the pool goes below a predefined threshold. Due to
this, flow control is incompatible with Rx frame queue taildrop
(both mechanisms target the case when processing of ingress
frames can't keep up with the Rx rate; for large frames, the number
of buffers in the pool may never get low enough to trigger pause
frames as long as taildrop is enabled). So we set pause frame
generation and Rx FQ taildrop as mutually exclusive.

Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 70 insertions, 10 deletions

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
index 2c6f9b1225b8..5402867272be 100644
--- a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
@@ -1208,9 +1208,37 @@ static void disable_ch_napi(struct dpaa2_eth_priv *priv)
 	}
 }
 
+static void dpaa2_eth_set_rx_taildrop(struct dpaa2_eth_priv *priv, bool enable)
+{
+	struct dpni_taildrop td = {0};
+	int i, err;
+
+	if (priv->rx_td_enabled == enable)
+		return;
+
+	td.enable = enable;
+	td.threshold = DPAA2_ETH_TAILDROP_THRESH;
+
+	for (i = 0; i < priv->num_fqs; i++) {
+		if (priv->fq[i].type != DPAA2_RX_FQ)
+			continue;
+		err = dpni_set_taildrop(priv->mc_io, 0, priv->mc_token,
+					DPNI_CP_QUEUE, DPNI_QUEUE_RX, 0,
+					priv->fq[i].flowid, &td);
+		if (err) {
+			netdev_err(priv->net_dev,
+				   "dpni_set_taildrop() failed\n");
+			break;
+		}
+	}
+
+	priv->rx_td_enabled = enable;
+}
+
 static int link_state_update(struct dpaa2_eth_priv *priv)
 {
 	struct dpni_link_state state = {0};
+	bool tx_pause;
 	int err;
 
 	err = dpni_get_link_state(priv->mc_io, 0, priv->mc_token, &state);
@@ -1220,6 +1248,14 @@ static int link_state_update(struct dpaa2_eth_priv *priv)
 		return err;
 	}
 
+	/* If Tx pause frame settings have changed, we need to update
+	 * Rx FQ taildrop configuration as well. We configure taildrop
+	 * only when pause frame generation is disabled.
+	 */
+	tx_pause = !!(state.options & DPNI_LINK_OPT_PAUSE) ^
+		   !!(state.options & DPNI_LINK_OPT_ASYM_PAUSE);
+	dpaa2_eth_set_rx_taildrop(priv, !tx_pause);
+
 	/* Chech link state; speed / duplex changes are not treated yet */
 	if (priv->link_state.up == state.up)
 		goto out;
@@ -2445,6 +2481,33 @@ static void set_enqueue_mode(struct dpaa2_eth_priv *priv)
 		priv->enqueue = dpaa2_eth_enqueue_fq;
 }
 
+static int set_pause(struct dpaa2_eth_priv *priv)
+{
+	struct device *dev = priv->net_dev->dev.parent;
+	struct dpni_link_cfg link_cfg = {0};
+	int err;
+
+	/* Get the default link options so we don't override other flags */
+	err = dpni_get_link_cfg(priv->mc_io, 0, priv->mc_token, &link_cfg);
+	if (err) {
+		dev_err(dev, "dpni_get_link_cfg() failed\n");
+		return err;
+	}
+
+	/* By default, enable both Rx and Tx pause frames */
+	link_cfg.options |= DPNI_LINK_OPT_PAUSE;
+	link_cfg.options &= ~DPNI_LINK_OPT_ASYM_PAUSE;
+	err = dpni_set_link_cfg(priv->mc_io, 0, priv->mc_token, &link_cfg);
+	if (err) {
+		dev_err(dev, "dpni_set_link_cfg() failed\n");
+		return err;
+	}
+
+	priv->link_state.options = link_cfg.options;
+
+	return 0;
+}
+
 /* Configure the DPNI object this interface is associated with */
 static int setup_dpni(struct fsl_mc_device *ls_dev)
 {
@@ -2500,6 +2563,13 @@ static int setup_dpni(struct fsl_mc_device *ls_dev)
 
 	set_enqueue_mode(priv);
 
+	/* Enable pause frame support */
+	if (dpaa2_eth_has_pause_support(priv)) {
+		err = set_pause(priv);
+		if (err)
+			goto close;
+	}
+
 	priv->cls_rules = devm_kzalloc(dev, sizeof(struct dpaa2_eth_cls_rule) *
 				       dpaa2_eth_fs_count(priv), GFP_KERNEL);
 	if (!priv->cls_rules)
@@ -2531,7 +2601,6 @@ static int setup_rx_flow(struct dpaa2_eth_priv *priv,
 	struct device *dev = priv->net_dev->dev.parent;
 	struct dpni_queue queue;
 	struct dpni_queue_id qid;
-	struct dpni_taildrop td;
 	int err;
 
 	err = dpni_get_queue(priv->mc_io, 0, priv->mc_token,
@@ -2556,15 +2625,6 @@ static int setup_rx_flow(struct dpaa2_eth_priv *priv,
 		return err;
 	}
 
-	td.enable = 1;
-	td.threshold = DPAA2_ETH_TAILDROP_THRESH;
-	err = dpni_set_taildrop(priv->mc_io, 0, priv->mc_token, DPNI_CP_QUEUE,
-				DPNI_QUEUE_RX, 0, fq->flowid, &td);
-	if (err) {
-		dev_err(dev, "dpni_set_threshold() failed\n");
-		return err;
-	}
-
 	/* xdp_rxq setup */
 	err = xdp_rxq_info_reg(&fq->channel->xdp_rxq, priv->net_dev,
 			       fq->flowid);