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 <[email protected]> --- Changes in v3: Split from previous 09/10 patch (no functional changes). Changes in v2: None. include/linux/dsa/sja1105.h | 11 +++++++++++ net/dsa/tag_sja1105.c | 15 +++++++++++++++ 2 files changed, 26 insertions(+) diff --git a/include/linux/dsa/sja1105.h b/include/linux/dsa/sja1105.h index f5d5f7823da6..4f09743b4713 100644 --- a/include/linux/dsa/sja1105.h +++ b/include/linux/dsa/sja1105.h @@ -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; diff --git a/net/dsa/tag_sja1105.c b/net/dsa/tag_sja1105.c index 7a56a27a1fd2..9ff7cfa6ea20 100644 --- a/net/dsa/tag_sja1105.c +++ b/net/dsa/tag_sja1105.c @@ -7,6 +7,21 @@ #include <linux/packing.h> #include "dsa_priv.h" +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. -- 2.17.1
