path: root/net
diff options
authorVladimir Oltean <>2021-02-14 00:38:00 +0200
committerDavid S. Miller <>2021-02-14 17:31:44 -0800
commitc8c0ba4fe2479033be946cfb5651d45c876c4c86 (patch)
treeee6d0f72c8b8aa1332026916bd73823bc68fd93b /net
parent924ee317f72459a49ac4130272c7d33063e60339 (diff)
net: dsa: felix: setup MMIO filtering rules for PTP when using tag_8021q
Since the tag_8021q tagger is software-defined, it has no means by itself for retrieving hardware timestamps of PTP event messages. Because we do want to support PTP on ocelot even with tag_8021q, we need to use the CPU port module for that. The RX timestamp is present in the Extraction Frame Header. And because we can't use NPI mode which redirects the CPU queues to an "external CPU" (meaning the ARM CPU running Linux), then we need to poll the CPU port module through the MMIO registers to retrieve TX and RX timestamps. Sadly, on NXP LS1028A, the Felix switch was integrated into the SoC without wiring the extraction IRQ line to the ARM GIC. So, if we want to be notified of any PTP packets received on the CPU port module, we have a problem. There is a possible workaround, which is to use the Ethernet CPU port as a notification channel that packets are available on the CPU port module as well. When a PTP packet is received by the DSA tagger (without timestamp, of course), we go to the CPU extraction queues, poll for it there, then we drop the original Ethernet packet and masquerade the packet retrieved over MMIO (plus the timestamp) as the original when we inject it up the stack. Create a quirk in struct felix is selected by the Felix driver (but not by Seville, since that doesn't support PTP at all). We want to do this such that the workaround is minimally invasive for future switches that don't require this workaround. The only traffic for which we need timestamps is PTP traffic, so add a redirection rule to the CPU port module for this. Currently we only have the need for PTP over L2, so redirection rules for UDP ports 319 and 320 are TBD for now. Note that for the workaround of matching of PTP-over-Ethernet-port with PTP-over-MMIO queues to work properly, both channels need to be absolutely lossless. There are two parts to achieving that: - We keep flow control enabled on the tag_8021q CPU port - We put the DSA master interface in promiscuous mode, so it will never drop a PTP frame (for the profiles we are interested in, these are sent to the multicast MAC addresses of 01-80-c2-00-00-0e and 01-1b-19-00-00-00). Signed-off-by: Vladimir Oltean <> Reviewed-by: Florian Fainelli <> Signed-off-by: David S. Miller <>
Diffstat (limited to 'net')
1 files changed, 1 insertions, 0 deletions
diff --git a/net/dsa/tag_ocelot_8021q.c b/net/dsa/tag_ocelot_8021q.c
index 8991ebf098a3..190255d06bef 100644
--- a/net/dsa/tag_ocelot_8021q.c
+++ b/net/dsa/tag_ocelot_8021q.c
@@ -60,6 +60,7 @@ static const struct dsa_device_ops ocelot_8021q_netdev_ops = {
.xmit = ocelot_xmit,
.rcv = ocelot_rcv,
.overhead = VLAN_HLEN,
+ .promisc_on_master = true,