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net: dsa: sja1105: Build a minimal understanding of meta frames

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Meta frames are sent on the CPU port by the switch if RX timestamping is
enabled. They contain a partial timestamp of the previous frame.

They are Ethernet frames with the Ethernet header constructed out of:

- SJA1105_META_DMAC
- SJA1105_META_SMAC
- ETH_P_SJA1105_META

The Ethernet payload will be decoded in a follow-up patch.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vladimir Oltean
2019-06-08 15:04:36 +03:00
committed by David S. Miller
parent 47ed985e97
commit d3f9b90bf1
2 changed files with 26 additions and 0 deletions
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15
net/dsa/tag_sja1105.c
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@@ -22,6 +22,21 @@ static inline bool sja1105_is_link_local(const struct sk_buff *skb)
return false;
}
static inline bool sja1105_is_meta_frame(const struct sk_buff *skb)
{
const struct ethhdr *hdr = eth_hdr(skb);
u64 smac = ether_addr_to_u64(hdr->h_source);
u64 dmac = ether_addr_to_u64(hdr->h_dest);
if (smac != SJA1105_META_SMAC)
return false;
if (dmac != SJA1105_META_DMAC)
return false;
if (ntohs(hdr->h_proto) != ETH_P_SJA1105_META)
return false;
return true;
}
/* This is the first time the tagger sees the frame on RX.
* Figure out if we can decode it, and if we can, annotate skb->cb with how we
* plan to do that, so we don't need to check again in the rcv function.