net: dsa: sja1105: Add a state machine for RX timestamping
Meta frame reception relies on the hardware keeping its promise that it will send no other traffic towards the CPU port between a link-local frame and a meta frame. Otherwise there is no other way to associate the meta frame with the link-local frame it's holding a timestamp of. The receive function is made stateful, and buffers a timestampable frame until its meta frame arrives, then merges the two, drops the meta and releases the link-local frame up the stack. Signed-off-by: Vladimir Oltean <olteanv@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -1600,6 +1600,14 @@ static int sja1105_setup(struct dsa_switch *ds)
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return sja1105_setup_8021q_tagging(ds, true);
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}
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static void sja1105_teardown(struct dsa_switch *ds)
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{
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struct sja1105_private *priv = ds->priv;
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cancel_work_sync(&priv->tagger_data.rxtstamp_work);
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skb_queue_purge(&priv->tagger_data.skb_rxtstamp_queue);
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}
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static int sja1105_mgmt_xmit(struct dsa_switch *ds, int port, int slot,
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struct sk_buff *skb, bool takets)
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{
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@ -1747,6 +1755,57 @@ static int sja1105_set_ageing_time(struct dsa_switch *ds,
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return sja1105_static_config_reload(priv);
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}
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#define to_tagger(d) \
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container_of((d), struct sja1105_tagger_data, rxtstamp_work)
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#define to_sja1105(d) \
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container_of((d), struct sja1105_private, tagger_data)
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static void sja1105_rxtstamp_work(struct work_struct *work)
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{
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struct sja1105_tagger_data *data = to_tagger(work);
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struct sja1105_private *priv = to_sja1105(data);
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struct sk_buff *skb;
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u64 now;
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mutex_lock(&priv->ptp_lock);
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now = priv->tstamp_cc.read(&priv->tstamp_cc);
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while ((skb = skb_dequeue(&data->skb_rxtstamp_queue)) != NULL) {
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struct skb_shared_hwtstamps *shwt = skb_hwtstamps(skb);
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u64 ts;
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*shwt = (struct skb_shared_hwtstamps) {0};
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ts = SJA1105_SKB_CB(skb)->meta_tstamp;
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ts = sja1105_tstamp_reconstruct(priv, now, ts);
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ts = timecounter_cyc2time(&priv->tstamp_tc, ts);
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shwt->hwtstamp = ns_to_ktime(ts);
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netif_rx_ni(skb);
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}
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mutex_unlock(&priv->ptp_lock);
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}
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/* Called from dsa_skb_defer_rx_timestamp */
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bool sja1105_port_rxtstamp(struct dsa_switch *ds, int port,
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struct sk_buff *skb, unsigned int type)
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{
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struct sja1105_private *priv = ds->priv;
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struct sja1105_tagger_data *data = &priv->tagger_data;
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if (!data->hwts_rx_en)
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return false;
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/* We need to read the full PTP clock to reconstruct the Rx
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* timestamp. For that we need a sleepable context.
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*/
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skb_queue_tail(&data->skb_rxtstamp_queue, skb);
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schedule_work(&data->rxtstamp_work);
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return true;
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}
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/* Called from dsa_skb_tx_timestamp. This callback is just to make DSA clone
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* the skb and have it available in DSA_SKB_CB in the .port_deferred_xmit
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* callback, where we will timestamp it synchronously.
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@ -1766,6 +1825,7 @@ bool sja1105_port_txtstamp(struct dsa_switch *ds, int port,
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static const struct dsa_switch_ops sja1105_switch_ops = {
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.get_tag_protocol = sja1105_get_tag_protocol,
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.setup = sja1105_setup,
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.teardown = sja1105_teardown,
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.set_ageing_time = sja1105_set_ageing_time,
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.phylink_validate = sja1105_phylink_validate,
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.phylink_mac_config = sja1105_mac_config,
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@ -1787,6 +1847,7 @@ static const struct dsa_switch_ops sja1105_switch_ops = {
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.port_mdb_add = sja1105_mdb_add,
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.port_mdb_del = sja1105_mdb_del,
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.port_deferred_xmit = sja1105_port_deferred_xmit,
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.port_rxtstamp = sja1105_port_rxtstamp,
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.port_txtstamp = sja1105_port_txtstamp,
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};
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@ -1885,6 +1946,7 @@ static int sja1105_probe(struct spi_device *spi)
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tagger_data = &priv->tagger_data;
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skb_queue_head_init(&tagger_data->skb_rxtstamp_queue);
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INIT_WORK(&tagger_data->rxtstamp_work, sja1105_rxtstamp_work);
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/* Connections between dsa_port and sja1105_port */
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for (i = 0; i < SJA1105_NUM_PORTS; i++) {
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@ -45,6 +45,13 @@ struct sja1105_tagger_data {
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bool hwts_rx_en;
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};
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struct sja1105_skb_cb {
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u32 meta_tstamp;
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};
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#define SJA1105_SKB_CB(skb) \
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((struct sja1105_skb_cb *)DSA_SKB_CB_PRIV(skb))
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struct sja1105_port {
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struct sja1105_tagger_data *data;
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struct dsa_port *dp;
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@ -110,6 +110,124 @@ static struct sk_buff *sja1105_xmit(struct sk_buff *skb,
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((pcp << VLAN_PRIO_SHIFT) | tx_vid));
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}
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static void sja1105_transfer_meta(struct sk_buff *skb,
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const struct sja1105_meta *meta)
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{
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struct ethhdr *hdr = eth_hdr(skb);
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hdr->h_dest[3] = meta->dmac_byte_3;
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hdr->h_dest[4] = meta->dmac_byte_4;
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SJA1105_SKB_CB(skb)->meta_tstamp = meta->tstamp;
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}
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/* This is a simple state machine which follows the hardware mechanism of
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* generating RX timestamps:
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*
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* After each timestampable skb (all traffic for which send_meta1 and
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* send_meta0 is true, aka all MAC-filtered link-local traffic) a meta frame
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* containing a partial timestamp is immediately generated by the switch and
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* sent as a follow-up to the link-local frame on the CPU port.
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*
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* The meta frames have no unique identifier (such as sequence number) by which
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* one may pair them to the correct timestampable frame.
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* Instead, the switch has internal logic that ensures no frames are sent on
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* the CPU port between a link-local timestampable frame and its corresponding
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* meta follow-up. It also ensures strict ordering between ports (lower ports
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* have higher priority towards the CPU port). For this reason, a per-port
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* data structure is not needed/desirable.
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*
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* This function pairs the link-local frame with its partial timestamp from the
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* meta follow-up frame. The full timestamp will be reconstructed later in a
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* work queue.
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*/
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static struct sk_buff
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*sja1105_rcv_meta_state_machine(struct sk_buff *skb,
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struct sja1105_meta *meta,
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bool is_link_local,
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bool is_meta)
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{
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struct sja1105_port *sp;
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struct dsa_port *dp;
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dp = dsa_slave_to_port(skb->dev);
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sp = dp->priv;
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/* Step 1: A timestampable frame was received.
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* Buffer it until we get its meta frame.
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*/
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if (is_link_local && sp->data->hwts_rx_en) {
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spin_lock(&sp->data->meta_lock);
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/* Was this a link-local frame instead of the meta
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* that we were expecting?
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*/
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if (sp->data->stampable_skb) {
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dev_err_ratelimited(dp->ds->dev,
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"Expected meta frame, is %12llx "
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"in the DSA master multicast filter?\n",
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SJA1105_META_DMAC);
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}
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/* Hold a reference to avoid dsa_switch_rcv
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* from freeing the skb.
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*/
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sp->data->stampable_skb = skb_get(skb);
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spin_unlock(&sp->data->meta_lock);
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/* Tell DSA we got nothing */
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return NULL;
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/* Step 2: The meta frame arrived.
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* Time to take the stampable skb out of the closet, annotate it
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* with the partial timestamp, and pretend that we received it
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* just now (basically masquerade the buffered frame as the meta
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* frame, which serves no further purpose).
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*/
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} else if (is_meta) {
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struct sk_buff *stampable_skb;
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spin_lock(&sp->data->meta_lock);
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stampable_skb = sp->data->stampable_skb;
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sp->data->stampable_skb = NULL;
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/* Was this a meta frame instead of the link-local
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* that we were expecting?
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*/
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if (!stampable_skb) {
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dev_err_ratelimited(dp->ds->dev,
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"Unexpected meta frame\n");
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spin_unlock(&sp->data->meta_lock);
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return NULL;
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}
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if (stampable_skb->dev != skb->dev) {
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dev_err_ratelimited(dp->ds->dev,
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"Meta frame on wrong port\n");
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spin_unlock(&sp->data->meta_lock);
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return NULL;
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}
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/* Free the meta frame and give DSA the buffered stampable_skb
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* for further processing up the network stack.
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*/
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kfree_skb(skb);
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skb = skb_copy(stampable_skb, GFP_ATOMIC);
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if (!skb) {
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dev_err_ratelimited(dp->ds->dev,
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"Failed to copy stampable skb\n");
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return NULL;
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}
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sja1105_transfer_meta(skb, meta);
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/* The cached copy will be freed now */
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skb_unref(stampable_skb);
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spin_unlock(&sp->data->meta_lock);
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}
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return skb;
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}
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static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
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struct net_device *netdev,
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struct packet_type *pt)
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@ -167,7 +285,8 @@ static struct sk_buff *sja1105_rcv(struct sk_buff *skb,
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if (is_tagged)
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skb = dsa_8021q_remove_header(skb);
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return skb;
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return sja1105_rcv_meta_state_machine(skb, &meta, is_link_local,
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is_meta);
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}
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static struct dsa_device_ops sja1105_netdev_ops = {
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