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>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/dsa/sja1105.h b/include/linux/dsa/sja1105.h
index 2c4fce4eaf0d..79435cfc20eb 100644
--- a/include/linux/dsa/sja1105.h
+++ b/include/linux/dsa/sja1105.h
@@ -45,6 +45,13 @@ struct sja1105_tagger_data {
         bool hwts_rx_en;
 };
 
+struct sja1105_skb_cb {
+        u32 meta_tstamp;
+};
+
+#define SJA1105_SKB_CB(skb) \
+        ((struct sja1105_skb_cb *)DSA_SKB_CB_PRIV(skb))
+
 struct sja1105_port {
         struct sja1105_tagger_data *data;
         struct dsa_port *dp;