net: dsa: sja1105: move ts_id from sja1105_tagger_data

The TX timestamp ID is incremented by the SJA1110 PTP timestamping
callback (->port_tx_timestamp) for every packet, when cloning it.
It isn't used by the tagger at all, even though it sits inside the
struct sja1105_tagger_data.

Also, serialization to this structure is currently done through
tagger_data->meta_lock, which is a cheap hack because the meta_lock
isn't used for anything else on SJA1110 (sja1105_rcv_meta_state_machine
isn't called).

This change moves ts_id from sja1105_tagger_data to sja1105_private and
introduces a dedicated spinlock for it, also in sja1105_private.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/sja1105/sja1105.h

@@ -261,6 +261,9 @@ struct sja1105_private {
 	 * the switch doesn't confuse them with one another.
 	 */
 	struct mutex mgmt_lock;
+	/* PTP two-step TX timestamp ID, and its serialization lock */
+	spinlock_t ts_id_lock;
+	u8 ts_id;
 	/* Serializes access to the dynamic config interface */
 	struct mutex dynamic_config_lock;
 	struct devlink_region **regions;

drivers/net/dsa/sja1105/sja1105_main.c

@@ -3348,6 +3348,7 @@ static int sja1105_probe(struct spi_device *spi)
 	mutex_init(&priv->ptp_data.lock);
 	mutex_init(&priv->dynamic_config_lock);
 	mutex_init(&priv->mgmt_lock);
+	spin_lock_init(&priv->ts_id_lock);
 
 	rc = sja1105_parse_dt(priv);
 	if (rc < 0) {

drivers/net/dsa/sja1105/sja1105_ptp.c

@@ -468,15 +468,15 @@ void sja1110_txtstamp(struct dsa_switch *ds, int port, struct sk_buff *skb)
 
 	skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
 
-	spin_lock(&tagger_data->meta_lock);
+	spin_lock(&priv->ts_id_lock);
 
-	ts_id = tagger_data->ts_id;
+	ts_id = priv->ts_id;
 	/* Deal automatically with 8-bit wraparound */
-	tagger_data->ts_id++;
+	priv->ts_id++;
 
 	SJA1105_SKB_CB(clone)->ts_id = ts_id;
 
-	spin_unlock(&tagger_data->meta_lock);
+	spin_unlock(&priv->ts_id_lock);
 
 	skb_queue_tail(&tagger_data->skb_txtstamp_queue, clone);
 }

include/linux/dsa/sja1105.h

@@ -51,7 +51,6 @@ struct sja1105_tagger_data {
 	 */
 	spinlock_t meta_lock;
 	unsigned long state;
-	u8 ts_id;
 	/* Used on SJA1110 where meta frames are generated only for
 	 * 2-step TX timestamps
 	 */