dpaa2-eth: Add PFC support through DCB ops

Add support in dpaa2-eth for PFC (Priority Flow Control)
through the DCB ops.

Instruct the hardware to respond to received PFC frames.
Current firmware doesn't allow us to selectively enable PFC
on the Rx side for some priorities only, so we will react to
all incoming PFC frames (and stop transmitting on the traffic
classes specified in the frame).

Also, configure the hardware to generate PFC frames based on Rx
congestion notifications. When a certain number of frames accumulate in
the ingress queues corresponding to a traffic class, priority flow
control frames are generated for that TC.

The number of PFC traffic classes available can be queried through
lldptool. Also, which of those traffic classes have PFC enabled is also
controlled through the same dcbnl_rtnl_ops callbacks.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 146 insertions, 0 deletions

diff --git a/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-dcb.c b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-dcb.c
new file mode 100644
index 000000000000..7ee07872af4d
--- /dev/null
+++ b/drivers/net/ethernet/freescale/dpaa2/dpaa2-eth-dcb.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause)
+/* Copyright 2020 NXP */
+
+#include "dpaa2-eth.h"
+
+static int dpaa2_eth_dcbnl_ieee_getpfc(struct net_device *net_dev,
+				       struct ieee_pfc *pfc)
+{
+	struct dpaa2_eth_priv *priv = netdev_priv(net_dev);
+
+	if (!(priv->link_state.options & DPNI_LINK_OPT_PFC_PAUSE))
+		return 0;
+
+	memcpy(pfc, &priv->pfc, sizeof(priv->pfc));
+	pfc->pfc_cap = dpaa2_eth_tc_count(priv);
+
+	return 0;
+}
+
+static inline bool is_prio_enabled(u8 pfc_en, u8 tc)
+{
+	return !!(pfc_en & (1 << tc));
+}
+
+static int set_pfc_cn(struct dpaa2_eth_priv *priv, u8 pfc_en)
+{
+	struct dpni_congestion_notification_cfg cfg = {0};
+	int i, err;
+
+	cfg.notification_mode = DPNI_CONG_OPT_FLOW_CONTROL;
+	cfg.units = DPNI_CONGESTION_UNIT_FRAMES;
+	cfg.message_iova = 0ULL;
+	cfg.message_ctx = 0ULL;
+
+	for (i = 0; i < dpaa2_eth_tc_count(priv); i++) {
+		if (is_prio_enabled(pfc_en, i)) {
+			cfg.threshold_entry = DPAA2_ETH_CN_THRESH_ENTRY(priv);
+			cfg.threshold_exit = DPAA2_ETH_CN_THRESH_EXIT(priv);
+		} else {
+			/* For priorities not set in the pfc_en mask, we leave
+			 * the congestion thresholds at zero, which effectively
+			 * disables generation of PFC frames for them
+			 */
+			cfg.threshold_entry = 0;
+			cfg.threshold_exit = 0;
+		}
+
+		err = dpni_set_congestion_notification(priv->mc_io, 0,
+						       priv->mc_token,
+						       DPNI_QUEUE_RX, i, &cfg);
+		if (err) {
+			netdev_err(priv->net_dev,
+				   "dpni_set_congestion_notification failed\n");
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static int dpaa2_eth_dcbnl_ieee_setpfc(struct net_device *net_dev,
+				       struct ieee_pfc *pfc)
+{
+	struct dpaa2_eth_priv *priv = netdev_priv(net_dev);
+	struct dpni_link_cfg link_cfg = {0};
+	int err;
+
+	if (pfc->mbc || pfc->delay)
+		return -EOPNOTSUPP;
+
+	/* If same PFC enabled mask, nothing to do */
+	if (priv->pfc.pfc_en == pfc->pfc_en)
+		return 0;
+
+	/* We allow PFC configuration even if it won't have any effect until
+	 * general pause frames are enabled
+	 */
+	if (!dpaa2_eth_rx_pause_enabled(priv->link_state.options) ||
+	    !dpaa2_eth_tx_pause_enabled(priv->link_state.options))
+		netdev_warn(net_dev, "Pause support must be enabled in order for PFC to work!\n");
+
+	link_cfg.rate = priv->link_state.rate;
+	link_cfg.options = priv->link_state.options;
+	if (pfc->pfc_en)
+		link_cfg.options |= DPNI_LINK_OPT_PFC_PAUSE;
+	else
+		link_cfg.options &= ~DPNI_LINK_OPT_PFC_PAUSE;
+	err = dpni_set_link_cfg(priv->mc_io, 0, priv->mc_token, &link_cfg);
+	if (err) {
+		netdev_err(net_dev, "dpni_set_link_cfg failed\n");
+		return err;
+	}
+
+	/* Configure congestion notifications for the enabled priorities */
+	err = set_pfc_cn(priv, pfc->pfc_en);
+	if (err)
+		return err;
+
+	memcpy(&priv->pfc, pfc, sizeof(priv->pfc));
+
+	return 0;
+}
+
+static u8 dpaa2_eth_dcbnl_getdcbx(struct net_device *net_dev)
+{
+	struct dpaa2_eth_priv *priv = netdev_priv(net_dev);
+
+	return priv->dcbx_mode;
+}
+
+static u8 dpaa2_eth_dcbnl_setdcbx(struct net_device *net_dev, u8 mode)
+{
+	struct dpaa2_eth_priv *priv = netdev_priv(net_dev);
+
+	return (mode != (priv->dcbx_mode)) ? 1 : 0;
+}
+
+static u8 dpaa2_eth_dcbnl_getcap(struct net_device *net_dev, int capid, u8 *cap)
+{
+	struct dpaa2_eth_priv *priv = netdev_priv(net_dev);
+
+	switch (capid) {
+	case DCB_CAP_ATTR_PFC:
+		*cap = true;
+		break;
+	case DCB_CAP_ATTR_PFC_TCS:
+		*cap = 1 << (dpaa2_eth_tc_count(priv) - 1);
+		break;
+	case DCB_CAP_ATTR_DCBX:
+		*cap = priv->dcbx_mode;
+		break;
+	default:
+		*cap = false;
+		break;
+	}
+
+	return 0;
+}
+
+const struct dcbnl_rtnl_ops dpaa2_eth_dcbnl_ops = {
+	.ieee_getpfc	= dpaa2_eth_dcbnl_ieee_getpfc,
+	.ieee_setpfc	= dpaa2_eth_dcbnl_ieee_setpfc,
+	.getdcbx	= dpaa2_eth_dcbnl_getdcbx,
+	.setdcbx	= dpaa2_eth_dcbnl_setdcbx,
+	.getcap		= dpaa2_eth_dcbnl_getcap,
+};