eth: fbnic: support ring channel get and set while down

Trivial implementation of ethtool channel get and set. Set is only
supported when device is closed, next patch will add code for
live reconfig.

Asymmetric configurations are supported (combined + extra Tx or Rx),
so are configurations with independent IRQs for Rx and Tx.
Having all 3 NAPI types (combined, Tx, Rx) is not supported.

We used to only call fbnic_reset_indir_tbl() during init.
Now that we call it after device had been register must
be careful not to override user config.

Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

drivers/net/ethernet/meta/fbnic/fbnic_ethtool.c

@@ -304,6 +304,68 @@ fbnic_set_rxfh(struct net_device *netdev, struct ethtool_rxfh_param *rxfh,
 	return 0;
 }
 
+static void fbnic_get_channels(struct net_device *netdev,
+			       struct ethtool_channels *ch)
+{
+	struct fbnic_net *fbn = netdev_priv(netdev);
+	struct fbnic_dev *fbd = fbn->fbd;
+
+	ch->max_rx = fbd->max_num_queues;
+	ch->max_tx = fbd->max_num_queues;
+	ch->max_combined = min(ch->max_rx, ch->max_tx);
+	ch->max_other =	FBNIC_NON_NAPI_VECTORS;
+
+	if (fbn->num_rx_queues > fbn->num_napi ||
+	    fbn->num_tx_queues > fbn->num_napi)
+		ch->combined_count = min(fbn->num_rx_queues,
+					 fbn->num_tx_queues);
+	else
+		ch->combined_count =
+			fbn->num_rx_queues + fbn->num_tx_queues - fbn->num_napi;
+	ch->rx_count = fbn->num_rx_queues - ch->combined_count;
+	ch->tx_count = fbn->num_tx_queues - ch->combined_count;
+	ch->other_count = FBNIC_NON_NAPI_VECTORS;
+}
+
+static void fbnic_set_queues(struct fbnic_net *fbn, struct ethtool_channels *ch,
+			     unsigned int max_napis)
+{
+	fbn->num_rx_queues = ch->rx_count + ch->combined_count;
+	fbn->num_tx_queues = ch->tx_count + ch->combined_count;
+	fbn->num_napi = min(ch->rx_count + ch->tx_count + ch->combined_count,
+			    max_napis);
+}
+
+static int fbnic_set_channels(struct net_device *netdev,
+			      struct ethtool_channels *ch)
+{
+	struct fbnic_net *fbn = netdev_priv(netdev);
+	unsigned int max_napis, standalone;
+	struct fbnic_dev *fbd = fbn->fbd;
+
+	max_napis = fbd->num_irqs - FBNIC_NON_NAPI_VECTORS;
+	standalone = ch->rx_count + ch->tx_count;
+
+	/* Limits for standalone queues:
+	 *  - each queue has it's own NAPI (num_napi >= rx + tx + combined)
+	 *  - combining queues (combined not 0, rx or tx must be 0)
+	 */
+	if ((ch->rx_count && ch->tx_count && ch->combined_count) ||
+	    (standalone && standalone + ch->combined_count > max_napis) ||
+	    ch->rx_count + ch->combined_count > fbd->max_num_queues ||
+	    ch->tx_count + ch->combined_count > fbd->max_num_queues ||
+	    ch->other_count != FBNIC_NON_NAPI_VECTORS)
+		return -EINVAL;
+
+	if (!netif_running(netdev)) {
+		fbnic_set_queues(fbn, ch, max_napis);
+		fbnic_reset_indir_tbl(fbn);
+		return 0;
+	}
+
+	return -EBUSY;
+}
+
 static int
 fbnic_get_ts_info(struct net_device *netdev,
 		  struct kernel_ethtool_ts_info *tsinfo)
@@ -417,6 +479,8 @@ static const struct ethtool_ops fbnic_ethtool_ops = {
 	.get_rxfh_indir_size	= fbnic_get_rxfh_indir_size,
 	.get_rxfh		= fbnic_get_rxfh,
 	.set_rxfh		= fbnic_set_rxfh,
+	.get_channels		= fbnic_get_channels,
+	.set_channels		= fbnic_set_channels,
 	.get_ts_info		= fbnic_get_ts_info,
 	.get_ts_stats		= fbnic_get_ts_stats,
 	.get_eth_mac_stats	= fbnic_get_eth_mac_stats,

drivers/net/ethernet/meta/fbnic/fbnic_rpc.c

@@ -13,6 +13,9 @@ void fbnic_reset_indir_tbl(struct fbnic_net *fbn)
 	unsigned int num_rx = fbn->num_rx_queues;
 	unsigned int i;
 
+	if (netif_is_rxfh_configured(fbn->netdev))
+		return;
+
 	for (i = 0; i < FBNIC_RPC_RSS_TBL_SIZE; i++)
 		fbn->indir_tbl[0][i] = ethtool_rxfh_indir_default(i, num_rx);
 }