net: lan743x: implement ndo_hwtstamp_get()

Permit programs such as "hwtstamp_ctl -i eth0" to retrieve the current
timestamping configuration of the NIC, rather than returning "Device
driver does not have support for non-destructive SIOCGHWTSTAMP."

The driver configures all channels with the same timestamping settings.
On TX, retrieve the settings of the first channel, those should be
representative for the entire NIC. On RX, save the filter settings in a
new adapter field.

Signed-off-by: Vladimir Oltean <[e-mail]>
Reviewed-by: Gerhard Engleder <[e-mail]>
Reviewed-by: Vadim Fedorenko <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/microchip/lan743x_main.c

···
 	default:
 			return -ERANGE;
 	}
+	adapter->rx_tstamp_filter = rx_filter;
 	return 0;
 }
 
···
 	.ndo_change_mtu		= lan743x_netdev_change_mtu,
 	.ndo_get_stats64	= lan743x_netdev_get_stats64,
 	.ndo_set_mac_address	= lan743x_netdev_set_mac_address,
+	.ndo_hwtstamp_get	= lan743x_ptp_hwtstamp_get,
 	.ndo_hwtstamp_set	= lan743x_ptp_hwtstamp_set,
 };
 

drivers/net/ethernet/microchip/lan743x_main.h

···
 	phy_interface_t		phy_interface;
 	struct phylink		*phylink;
 	struct phylink_config	phylink_config;
+	int			rx_tstamp_filter;
 };
 
 #define LAN743X_COMPONENT_FLAG_RX(channel)  BIT(20 + (channel))

drivers/net/ethernet/microchip/lan743x_ptp.c

···
 	lan743x_ptp_tx_ts_complete(adapter);
 }
 
+int lan743x_ptp_hwtstamp_get(struct net_device *netdev,
+			     struct kernel_hwtstamp_config *config)
+{
+	struct lan743x_adapter *adapter = netdev_priv(netdev);
+	struct lan743x_tx *tx = &adapter->tx[0];
+
+	if (tx->ts_flags & TX_TS_FLAG_ONE_STEP_SYNC)
+		config->tx_type = HWTSTAMP_TX_ONESTEP_SYNC;
+	else if (tx->ts_flags & TX_TS_FLAG_TIMESTAMPING_ENABLED)
+		config->tx_type = HWTSTAMP_TX_ON;
+	else
+		config->tx_type = HWTSTAMP_TX_OFF;
+
+	config->rx_filter = adapter->rx_tstamp_filter;
+
+	return 0;
+}
+
 int lan743x_ptp_hwtstamp_set(struct net_device *netdev,
 			     struct kernel_hwtstamp_config *config,
 			     struct netlink_ext_ack *extack)

drivers/net/ethernet/microchip/lan743x_ptp.h

···
 void lan743x_ptp_close(struct lan743x_adapter *adapter);
 void lan743x_ptp_update_latency(struct lan743x_adapter *adapter,
 				u32 link_speed);
-
+int lan743x_ptp_hwtstamp_get(struct net_device *netdev,
+			     struct kernel_hwtstamp_config *config);
 int lan743x_ptp_hwtstamp_set(struct net_device *netdev,
 			     struct kernel_hwtstamp_config *config,
 			     struct netlink_ext_ack *extack);