linux.git/include/linux/dsa, branch v5.14 Linux kernel source tree net: dsa: sja1105: implement TX timestamping for SJA1110 2021-06-11T19:45:38+00:00 Vladimir Oltean vladimir.oltean@nxp.com 2021-06-11T19:01:31+00:00 566b18c8b752f67c4e82f0eb4563dd71f84a8799 The TX timestamping procedure for SJA1105 is a bit unconventional because the transmit procedure itself is unconventional. Control packets (and therefore PTP as well) are transmitted to a specific port in SJA1105 using "management routes" which must be written over SPI to the switch. These are one-shot rules that match by destination MAC address on traffic coming from the CPU port, and select the precise destination port for that packet. So to transmit a packet from NET_TX softirq context, we actually need to defer to a process context so that we can perform that SPI write before we send the packet. The DSA master dev_queue_xmit() runs in process context, and we poll until the switch confirms it took the TX timestamp, then we annotate the skb clone with that TX timestamp. This is why the sja1105 driver does not need an skb queue for TX timestamping. But the SJA1110 is a bit (not much!) more conventional, and you can request 2-step TX timestamping through the DSA header, as well as give the switch a cookie (timestamp ID) which it will give back to you when it has the timestamp. So now we do need a queue for keeping the skb clones until their TX timestamps become available. The interesting part is that the metadata frames from SJA1105 haven't disappeared completely. On SJA1105 they were used as follow-ups which contained RX timestamps, but on SJA1110 they are actually TX completion packets, which contain a variable (up to 32) array of timestamps. Why an array? Because: - not only is the TX timestamp on the egress port being communicated, but also the RX timestamp on the CPU port. Nice, but we don't care about that, so we ignore it. - because a packet could be multicast to multiple egress ports, each port takes its own timestamp, and the TX completion packet contains the individual timestamps on each port. This is unconventional because switches typically have a timestamping FIFO and raise an interrupt, but this one doesn't. So the tagger needs to detect and parse meta frames, and call into the main switch driver, which pairs the timestamps with the skbs in the TX timestamping queue which are waiting for one. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
The TX timestamping procedure for SJA1105 is a bit unconventional
because the transmit procedure itself is unconventional.

Control packets (and therefore PTP as well) are transmitted to a
specific port in SJA1105 using "management routes" which must be written
over SPI to the switch. These are one-shot rules that match by
destination MAC address on traffic coming from the CPU port, and select
the precise destination port for that packet. So to transmit a packet
from NET_TX softirq context, we actually need to defer to a process
context so that we can perform that SPI write before we send the packet.
The DSA master dev_queue_xmit() runs in process context, and we poll
until the switch confirms it took the TX timestamp, then we annotate the
skb clone with that TX timestamp. This is why the sja1105 driver does
not need an skb queue for TX timestamping.

But the SJA1110 is a bit (not much!) more conventional, and you can
request 2-step TX timestamping through the DSA header, as well as give
the switch a cookie (timestamp ID) which it will give back to you when
it has the timestamp. So now we do need a queue for keeping the skb
clones until their TX timestamps become available.

The interesting part is that the metadata frames from SJA1105 haven't
disappeared completely. On SJA1105 they were used as follow-ups which
contained RX timestamps, but on SJA1110 they are actually TX completion
packets, which contain a variable (up to 32) array of timestamps.
Why an array? Because:
- not only is the TX timestamp on the egress port being communicated,
  but also the RX timestamp on the CPU port. Nice, but we don't care
  about that, so we ignore it.
- because a packet could be multicast to multiple egress ports, each
  port takes its own timestamp, and the TX completion packet contains
  the individual timestamps on each port.

This is unconventional because switches typically have a timestamping
FIFO and raise an interrupt, but this one doesn't. So the tagger needs
to detect and parse meta frames, and call into the main switch driver,
which pairs the timestamps with the skbs in the TX timestamping queue
which are waiting for one.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: dsa: add support for the SJA1110 native tagging protocol 2021-06-11T19:45:38+00:00 Vladimir Oltean vladimir.oltean@nxp.com 2021-06-11T19:01:29+00:00 4913b8ebf8a9c56ce66466b4daa07d7d4678cdd8 The SJA1110 has improved a few things compared to SJA1105: - To send a control packet from the host port with SJA1105, one needed to program a one-shot "management route" over SPI. This is no longer true with SJA1110, you can actually send "in-band control extensions" in the packets sent by DSA, these are in fact DSA tags which contain the destination port and switch ID. - When receiving a control packet from the switch with SJA1105, the source port and switch ID were written in bytes 3 and 4 of the destination MAC address of the frame (which was a very poor shot at a DSA header). If the control packet also had an RX timestamp, that timestamp was sent in an actual follow-up packet, so there were reordering concerns on multi-core/multi-queue DSA masters, where the metadata frame with the RX timestamp might get processed before the actual packet to which that timestamp belonged (there is no way to pair a packet to its timestamp other than the order in which they were received). On SJA1110, this is no longer true, control packets have the source port, switch ID and timestamp all in the DSA tags. - Timestamps from the switch were partial: to get a 64-bit timestamp as required by PTP stacks, one would need to take the partial 24-bit or 32-bit timestamp from the packet, then read the current PTP time very quickly, and then patch in the high bits of the current PTP time into the captured partial timestamp, to reconstruct what the full 64-bit timestamp must have been. That is awful because packet processing is done in NAPI context, but reading the current PTP time is done over SPI and therefore needs sleepable context. But it also aggravated a few things: - Not only is there a DSA header in SJA1110, but there is a DSA trailer in fact, too. So DSA needs to be extended to support taggers which have both a header and a trailer. Very unconventional - my understanding is that the trailer exists because the timestamps couldn't be prepared in time for putting them in the header area. - Like SJA1105, not all packets sent to the CPU have the DSA tag added to them, only control packets do: * the ones which match the destination MAC filters/traps in MAC_FLTRES1 and MAC_FLTRES0 * the ones which match FDB entries which have TRAP or TAKETS bits set So we could in theory hack something up to request the switch to take timestamps for all packets that reach the CPU, and those would be DSA-tagged and contain the source port / switch ID by virtue of the fact that there needs to be a timestamp trailer provided. BUT: - The SJA1110 does not parse its own DSA tags in a way that is useful for routing in cross-chip topologies, a la Marvell. And the sja1105 driver already supports cross-chip bridging from the SJA1105 days. It does that by automatically setting up the DSA links as VLAN trunks which contain all the necessary tag_8021q RX VLANs that must be communicated between the switches that span the same bridge. So when using tag_8021q on sja1105, it is possible to have 2 switches with ports sw0p0, sw0p1, sw1p0, sw1p1, and 2 VLAN-unaware bridges br0 and br1, and br0 can take sw0p0 and sw1p0, and br1 can take sw0p1 and sw1p1, and forwarding will happen according to the expected rules of the Linux bridge. We like that, and we don't want that to go away, so as a matter of fact, the SJA1110 tagger still needs to support tag_8021q. So the sja1110 tagger is a hybrid between tag_8021q for data packets, and the native hardware support for control packets. On RX, packets have a 13-byte trailer if they contain an RX timestamp. That trailer is padded in such a way that its byte 8 (the start of the "residence time" field - not parsed by Linux because we don't care) is aligned on a 16 byte boundary. So the padding has a variable length between 0 and 15 bytes. The DSA header contains the offset of the beginning of the padding relative to the beginning of the frame (and the end of the padding is obviously the end of the packet minus 13 bytes, the length of the trailer). So we discard it. Packets which don't have a trailer contain the source port and switch ID information in the header (they are "trap-to-host" packets). Packets which have a trailer contain the source port and switch ID in the trailer. On TX, the destination port mask and switch ID is always in the trailer, so we always need to say in the header that a trailer is present. The header needs a custom EtherType and this was chosen as 0xdadc, after 0xdada which is for Marvell and 0xdadb which is for VLANs in VLAN-unaware mode on SJA1105 (and SJA1110 in fact too). Because we use tag_8021q in concert with the native tagging protocol, control packets will have 2 DSA tags. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
The SJA1110 has improved a few things compared to SJA1105:

- To send a control packet from the host port with SJA1105, one needed
  to program a one-shot "management route" over SPI. This is no longer
  true with SJA1110, you can actually send "in-band control extensions"
  in the packets sent by DSA, these are in fact DSA tags which contain
  the destination port and switch ID.

- When receiving a control packet from the switch with SJA1105, the
  source port and switch ID were written in bytes 3 and 4 of the
  destination MAC address of the frame (which was a very poor shot at a
  DSA header). If the control packet also had an RX timestamp, that
  timestamp was sent in an actual follow-up packet, so there were
  reordering concerns on multi-core/multi-queue DSA masters, where the
  metadata frame with the RX timestamp might get processed before the
  actual packet to which that timestamp belonged (there is no way to
  pair a packet to its timestamp other than the order in which they were
  received). On SJA1110, this is no longer true, control packets have
  the source port, switch ID and timestamp all in the DSA tags.

- Timestamps from the switch were partial: to get a 64-bit timestamp as
  required by PTP stacks, one would need to take the partial 24-bit or
  32-bit timestamp from the packet, then read the current PTP time very
  quickly, and then patch in the high bits of the current PTP time into
  the captured partial timestamp, to reconstruct what the full 64-bit
  timestamp must have been. That is awful because packet processing is
  done in NAPI context, but reading the current PTP time is done over
  SPI and therefore needs sleepable context.

But it also aggravated a few things:

- Not only is there a DSA header in SJA1110, but there is a DSA trailer
  in fact, too. So DSA needs to be extended to support taggers which
  have both a header and a trailer. Very unconventional - my understanding
  is that the trailer exists because the timestamps couldn't be prepared
  in time for putting them in the header area.

- Like SJA1105, not all packets sent to the CPU have the DSA tag added
  to them, only control packets do:

  * the ones which match the destination MAC filters/traps in
    MAC_FLTRES1 and MAC_FLTRES0
  * the ones which match FDB entries which have TRAP or TAKETS bits set

  So we could in theory hack something up to request the switch to take
  timestamps for all packets that reach the CPU, and those would be
  DSA-tagged and contain the source port / switch ID by virtue of the
  fact that there needs to be a timestamp trailer provided. BUT:

- The SJA1110 does not parse its own DSA tags in a way that is useful
  for routing in cross-chip topologies, a la Marvell. And the sja1105
  driver already supports cross-chip bridging from the SJA1105 days.
  It does that by automatically setting up the DSA links as VLAN trunks
  which contain all the necessary tag_8021q RX VLANs that must be
  communicated between the switches that span the same bridge. So when
  using tag_8021q on sja1105, it is possible to have 2 switches with
  ports sw0p0, sw0p1, sw1p0, sw1p1, and 2 VLAN-unaware bridges br0 and
  br1, and br0 can take sw0p0 and sw1p0, and br1 can take sw0p1 and
  sw1p1, and forwarding will happen according to the expected rules of
  the Linux bridge.
  We like that, and we don't want that to go away, so as a matter of
  fact, the SJA1110 tagger still needs to support tag_8021q.

So the sja1110 tagger is a hybrid between tag_8021q for data packets,
and the native hardware support for control packets.

On RX, packets have a 13-byte trailer if they contain an RX timestamp.
That trailer is padded in such a way that its byte 8 (the start of the
"residence time" field - not parsed by Linux because we don't care) is
aligned on a 16 byte boundary. So the padding has a variable length
between 0 and 15 bytes. The DSA header contains the offset of the
beginning of the padding relative to the beginning of the frame (and the
end of the padding is obviously the end of the packet minus 13 bytes,
the length of the trailer). So we discard it.

Packets which don't have a trailer contain the source port and switch ID
information in the header (they are "trap-to-host" packets). Packets
which have a trailer contain the source port and switch ID in the trailer.

On TX, the destination port mask and switch ID is always in the trailer,
so we always need to say in the header that a trailer is present.

The header needs a custom EtherType and this was chosen as 0xdadc, after
0xdada which is for Marvell and 0xdadb which is for VLANs in
VLAN-unaware mode on SJA1105 (and SJA1110 in fact too).

Because we use tag_8021q in concert with the native tagging protocol,
control packets will have 2 DSA tags.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: dsa: sja1105: make SJA1105_SKB_CB fit a full timestamp 2021-06-11T19:45:38+00:00 Vladimir Oltean vladimir.oltean@nxp.com 2021-06-11T19:01:28+00:00 617ef8d9377b9aac381c023cd0823da264c2f463 In SJA1105, RX timestamps for packets sent to the CPU are transmitted in separate follow-up packets (metadata frames). These contain partial timestamps (24 or 32 bits) which are kept in SJA1105_SKB_CB(skb)->meta_tstamp. Thankfully, SJA1110 improved that, and the RX timestamps are now transmitted in-band with the actual packet, in the timestamp trailer. The RX timestamps are now full-width 64 bits. Because we process the RX DSA tags in the rcv() method in the tagger, but we would like to preserve the DSA code structure in that we populate the skb timestamp in the port_rxtstamp() call which only happens later, the implication is that we must somehow pass the 64-bit timestamp from the rcv() method all the way to port_rxtstamp(). We can use the skb->cb for that. Rename the meta_tstamp from struct sja1105_skb_cb from "meta_tstamp" to "tstamp", and increase its size to 64 bits. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
In SJA1105, RX timestamps for packets sent to the CPU are transmitted in
separate follow-up packets (metadata frames). These contain partial
timestamps (24 or 32 bits) which are kept in SJA1105_SKB_CB(skb)->meta_tstamp.

Thankfully, SJA1110 improved that, and the RX timestamps are now
transmitted in-band with the actual packet, in the timestamp trailer.
The RX timestamps are now full-width 64 bits.

Because we process the RX DSA tags in the rcv() method in the tagger,
but we would like to preserve the DSA code structure in that we populate
the skb timestamp in the port_rxtstamp() call which only happens later,
the implication is that we must somehow pass the 64-bit timestamp from
the rcv() method all the way to port_rxtstamp(). We can use the skb->cb
for that.

Rename the meta_tstamp from struct sja1105_skb_cb from "meta_tstamp" to
"tstamp", and increase its size to 64 bits.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: dsa: tag_8021q: refactor RX VLAN parsing into a dedicated function 2021-06-11T19:45:38+00:00 Vladimir Oltean vladimir.oltean@nxp.com 2021-06-11T19:01:27+00:00 233697b3b3f60b17d02ca2a35230aee0ac6f1759 The added value of this function is that it can deal with both the case where the VLAN header is in the skb head, as well as in the offload field. This is something I was not able to do using other functions in the network stack. Since both ocelot-8021q and sja1105 need to do the same stuff, let's make it a common service provided by tag_8021q. This is done as refactoring for the new SJA1110 tagger, which partly uses tag_8021q as well (just like SJA1105), and will be the third caller. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
The added value of this function is that it can deal with both the case
where the VLAN header is in the skb head, as well as in the offload field.
This is something I was not able to do using other functions in the
network stack.

Since both ocelot-8021q and sja1105 need to do the same stuff, let's
make it a common service provided by tag_8021q.

This is done as refactoring for the new SJA1110 tagger, which partly
uses tag_8021q as well (just like SJA1105), and will be the third caller.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: dsa: tag_8021q: remove shim declarations 2021-06-11T19:45:38+00:00 Vladimir Oltean vladimir.oltean@nxp.com 2021-06-11T19:01:26+00:00 ab6a303c5440156dd475b5884cff26a7245630f8 All users of tag_8021q select it in Kconfig, so shim functions are not needed because it is not possible for it to be disabled and its callers enabled. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
All users of tag_8021q select it in Kconfig, so shim functions are not
needed because it is not possible for it to be disabled and its callers
enabled.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: dsa: free skb->cb usage in core driver 2021-04-27T21:10:15+00:00 Yangbo Lu yangbo.lu@nxp.com 2021-04-27T04:22:00+00:00 c4b364ce1270d689ee5010001344b8eae3685f32 Free skb->cb usage in core driver and let device drivers decide to use or not. The reason having a DSA_SKB_CB(skb)->clone was because dsa_skb_tx_timestamp() which may set the clone pointer was called before p->xmit() which would use the clone if any, and the device driver has no way to initialize the clone pointer. This patch just put memset(skb->cb, 0, sizeof(skb->cb)) at beginning of dsa_slave_xmit(). Some new features in the future, like one-step timestamp may need more bytes of skb->cb to use in dsa_skb_tx_timestamp(), and p->xmit(). Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com> Acked-by: Richard Cochran <richardcochran@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Free skb->cb usage in core driver and let device drivers decide to
use or not. The reason having a DSA_SKB_CB(skb)->clone was because
dsa_skb_tx_timestamp() which may set the clone pointer was called
before p->xmit() which would use the clone if any, and the device
driver has no way to initialize the clone pointer.

This patch just put memset(skb->cb, 0, sizeof(skb->cb)) at beginning
of dsa_slave_xmit(). Some new features in the future, like one-step
timestamp may need more bytes of skb->cb to use in
dsa_skb_tx_timestamp(), and p->xmit().

Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: ocelot: Remove ocelot_xfh_get_cpuq 2021-03-16T22:49:52+00:00 Horatiu Vultur horatiu.vultur@microchip.com 2021-03-16T20:10:19+00:00 2ed2c5f0391106406ead3a74bfa571575eafe8b6 Now when extracting frames from CPU the cpuq is not used anymore so remove it. Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Now when extracting frames from CPU the cpuq is not used anymore so
remove it.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: mscc: ocelot: Add support for MRP 2021-02-16T22:47:46+00:00 Horatiu Vultur horatiu.vultur@microchip.com 2021-02-16T21:42:03+00:00 d8ea7ff3995ead5193313c72c0d97c9c16c83be9 Add basic support for MRP. The HW will just trap all MRP frames on the ring ports to CPU and allow the SW to process them. In this way it is possible to for this node to behave both as MRM and MRC. Current limitations are: - it doesn't support Interconnect roles. - it supports only a single ring. - the HW should be able to do forwarding of MRP Test frames so the SW will not need to do this. So it would be able to have the role MRC without SW support. Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Add basic support for MRP. The HW will just trap all MRP frames on the
ring ports to CPU and allow the SW to process them. In this way it is
possible to for this node to behave both as MRM and MRC.

Current limitations are:
- it doesn't support Interconnect roles.
- it supports only a single ring.
- the HW should be able to do forwarding of MRP Test frames so the SW
  will not need to do this. So it would be able to have the role MRC
  without SW support.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: dsa: tag_ocelot: create separate tagger for Seville 2021-02-15T01:31:44+00:00 Vladimir Oltean vladimir.oltean@nxp.com 2021-02-13T22:37:58+00:00 7c4bb540e9173c914c2091fdd9b6aee3c2a3e1e5 The ocelot tagger is a hot mess currently, it relies on memory initialized by the attached driver for basic frame transmission. This is against all that DSA tagging protocols stand for, which is that the transmission and reception of a DSA-tagged frame, the data path, should be independent from the switch control path, because the tag protocol is in principle hot-pluggable and reusable across switches (even if in practice it wasn't until very recently). But if another driver like dsa_loop wants to make use of tag_ocelot, it couldn't. This was done to have common code between Felix and Ocelot, which have one bit difference in the frame header format. Quoting from commit 67c2404922c2 ("net: dsa: felix: create a template for the DSA tags on xmit"): Other alternatives have been analyzed, such as: - Create a separate tag_seville.c: too much code duplication for just 1 bit field difference. - Create a separate DSA_TAG_PROTO_SEVILLE under tag_ocelot.c, just like tag_brcm.c, which would have a separate .xmit function. Again, too much code duplication for just 1 bit field difference. - Allocate the template from the init function of the tag_ocelot.c module, instead of from the driver: couldn't figure out a method of accessing the correct port template corresponding to the correct tagger in the .xmit function. The really interesting part is that Seville should have had its own tagging protocol defined - it is not compatible on the wire with Ocelot, even for that single bit. In principle, a packet generated by DSA_TAG_PROTO_OCELOT when booted on NXP LS1028A would look in a certain way, but when booted on NXP T1040 it would look differently. The reverse is also true: a packet generated by a Seville switch would be interpreted incorrectly by Wireshark if it was told it was generated by an Ocelot switch. Actually things are a bit more nuanced. If we concentrate only on the DSA tag, what I said above is true, but Ocelot/Seville also support an optional DSA tag prefix, which can be short or long, and it is possible to distinguish the two taggers based on an integer constant put in that prefix. Nonetheless, creating a separate tagger is still justified, since the tag prefix is optional, and without it, there is again no way to distinguish. Claiming backwards binary compatibility is a bit more tough, since I've already changed the format of tag_ocelot once, in commit 5124197ce58b ("net: dsa: tag_ocelot: use a short prefix on both ingress and egress"). Therefore I am not very concerned with treating this as a bugfix and backporting it to stable kernels (which would be another mess due to the fact that there would be lots of conflicts with the other DSA_TAG_PROTO* definitions). It's just simpler to say that the string values of the taggers have ABI value starting with kernel 5.12, which will be when the changing of tag protocol via /sys/class/net/<dsa-master>/dsa/tagging goes live. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
The ocelot tagger is a hot mess currently, it relies on memory
initialized by the attached driver for basic frame transmission.
This is against all that DSA tagging protocols stand for, which is that
the transmission and reception of a DSA-tagged frame, the data path,
should be independent from the switch control path, because the tag
protocol is in principle hot-pluggable and reusable across switches
(even if in practice it wasn't until very recently). But if another
driver like dsa_loop wants to make use of tag_ocelot, it couldn't.

This was done to have common code between Felix and Ocelot, which have
one bit difference in the frame header format. Quoting from commit
67c2404922c2 ("net: dsa: felix: create a template for the DSA tags on
xmit"):

    Other alternatives have been analyzed, such as:
    - Create a separate tag_seville.c: too much code duplication for just 1
      bit field difference.
    - Create a separate DSA_TAG_PROTO_SEVILLE under tag_ocelot.c, just like
      tag_brcm.c, which would have a separate .xmit function. Again, too
      much code duplication for just 1 bit field difference.
    - Allocate the template from the init function of the tag_ocelot.c
      module, instead of from the driver: couldn't figure out a method of
      accessing the correct port template corresponding to the correct
      tagger in the .xmit function.

The really interesting part is that Seville should have had its own
tagging protocol defined - it is not compatible on the wire with Ocelot,
even for that single bit. In principle, a packet generated by
DSA_TAG_PROTO_OCELOT when booted on NXP LS1028A would look in a certain
way, but when booted on NXP T1040 it would look differently. The reverse
is also true: a packet generated by a Seville switch would be
interpreted incorrectly by Wireshark if it was told it was generated by
an Ocelot switch.

Actually things are a bit more nuanced. If we concentrate only on the
DSA tag, what I said above is true, but Ocelot/Seville also support an
optional DSA tag prefix, which can be short or long, and it is possible
to distinguish the two taggers based on an integer constant put in that
prefix. Nonetheless, creating a separate tagger is still justified,
since the tag prefix is optional, and without it, there is again no way
to distinguish.

Claiming backwards binary compatibility is a bit more tough, since I've
already changed the format of tag_ocelot once, in commit 5124197ce58b
("net: dsa: tag_ocelot: use a short prefix on both ingress and egress").
Therefore I am not very concerned with treating this as a bugfix and
backporting it to stable kernels (which would be another mess due to the
fact that there would be lots of conflicts with the other DSA_TAG_PROTO*
definitions). It's just simpler to say that the string values of the
taggers have ABI value starting with kernel 5.12, which will be when the
changing of tag protocol via /sys/class/net/<dsa-master>/dsa/tagging
goes live.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: mscc: ocelot: use common tag parsing code with DSA 2021-02-15T01:31:44+00:00 Vladimir Oltean vladimir.oltean@nxp.com 2021-02-13T22:37:56+00:00 40d3f295b5feda409784e569550057b5fbc2a295 The Injection Frame Header and Extraction Frame Header that the switch prepends to frames over the NPI port is also prepended to frames delivered over the CPU port module's queues. Let's unify the handling of the frame headers by making the ocelot driver call some helpers exported by the DSA tagger. Among other things, this allows us to get rid of the strange cpu_to_be32 when transmitting the Injection Frame Header on ocelot, since the packing API uses network byte order natively (when "quirks" is 0). The comments above ocelot_gen_ifh talk about setting pop_cnt to 3, and the cpu extraction queue mask to something, but the code doesn't do it, so we don't do it either. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
The Injection Frame Header and Extraction Frame Header that the switch
prepends to frames over the NPI port is also prepended to frames
delivered over the CPU port module's queues.

Let's unify the handling of the frame headers by making the ocelot
driver call some helpers exported by the DSA tagger. Among other things,
this allows us to get rid of the strange cpu_to_be32 when transmitting
the Injection Frame Header on ocelot, since the packing API uses
network byte order natively (when "quirks" is 0).

The comments above ocelot_gen_ifh talk about setting pop_cnt to 3, and
the cpu extraction queue mask to something, but the code doesn't do it,
so we don't do it either.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>