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Commit d3f9b90b authored by Vladimir Oltean's avatar Vladimir Oltean Committed by David S. Miller
Browse files

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



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: default avatarVladimir Oltean <olteanv@gmail.com>
Reviewed-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 47ed985e

include/linux/dsa/sja1105.h

+11 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <net/dsa.h>



#define ETH_P_SJA1105				ETH_P_DSA_8021Q

#define ETH_P_SJA1105_META			0x0008



/* IEEE 802.3 Annex 57A: Slow Protocols PDUs (01:80:C2:xx:xx:xx) */

#define SJA1105_LINKLOCAL_FILTER_A		0x0180C2000000ull
@@ -20,6 +21,16 @@ 
#define SJA1105_LINKLOCAL_FILTER_B		0x011B19000000ull

#define SJA1105_LINKLOCAL_FILTER_B_MASK		0xFFFFFF000000ull



/* Source and Destination MAC of follow-up meta frames.

 * Whereas the choice of SMAC only affects the unique identification of the

 * switch as sender of meta frames, the DMAC must be an address that is present

 * in the DSA master port's multicast MAC filter.

 * 01-80-C2-00-00-0E is a good choice for this, as all profiles of IEEE 1588

 * over L2 use this address for some purpose already.

 */

#define SJA1105_META_SMAC			0x222222222222ull

#define SJA1105_META_DMAC			0x0180C200000Eull



struct sja1105_port {

	struct dsa_port *dp;

	bool hwts_tx_en;

net/dsa/tag_sja1105.c

+15 −0
Original line number Diff line number Diff line
@@ -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.