net: dsa: tag_sja1105: remove "inline" keyword

The convention is to not use the "inline" keyword for functions in C
files, but to let the compiler choose.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240206112927.4134375-2-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: fill in MODULE_DESCRIPTION()s for DSA tags

W=1 builds now warn if module is built without a MODULE_DESCRIPTION().
Add descriptions to all the DSA tag modules.

The descriptions are copy/pasted Kconfig names, with s/^Tag/DSA tag/.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Acked-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Acked-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/20240104143759.1318137-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: dsa: Use conduit and user terms

Use more inclusive terms throughout the DSA subsystem by moving away
from "master" which is replaced by "conduit" and "slave" which is
replaced by "user". No functional changes.

Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20231023181729.1191071-2-florian.fainelli@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: dsa: sja1105: always enable the send_meta options

incl_srcpt has the limitation, mentioned in commit b4638af8885a ("net:
dsa: sja1105: always enable the INCL_SRCPT option"), that frames with a
MAC DA of 01:80:c2:xx:yy:zz will be received as 01:80:c2:00:00:zz unless
PTP RX timestamping is enabled.

The incl_srcpt option was initially unconditionally enabled, then that
changed with commit 42824463d38d ("net: dsa: sja1105: Limit use of
incl_srcpt to bridge+vlan mode"), then again with b4638af8885a ("net:
dsa: sja1105: always enable the INCL_SRCPT option"). Bottom line is that
it now needs to be always enabled, otherwise the driver does not have a
reliable source of information regarding source_port and switch_id for
link-local traffic (tag_8021q VLANs may be imprecise since now they
identify an entire bridging domain when ports are not standalone).

If we accept that PTP RX timestamping (and therefore, meta frame
generation) is always enabled in hardware, then that limitation could be
avoided and packets with any MAC DA can be properly received, because
meta frames do contain the original bytes from the MAC DA of their
associated link-local packet.

This change enables meta frame generation unconditionally, which also
has the nice side effects of simplifying the switch control path
(a switch reset is no longer required on hwtstamping settings change)
and the tagger data path (it no longer needs to be informed whether to
expect meta frames or not - it always does).

Fixes: 227d07a07ef1 ("net: dsa: sja1105: Add support for traffic through standalone ports")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: fix MAC DA patching from meta frames

The SJA1105 manual says that at offset 4 into the meta frame payload we
have "MAC destination byte 2" and at offset 5 we have "MAC destination
byte 1". These are counted from the LSB, so byte 1 is h_dest[ETH_HLEN-2]
aka h_dest[4] and byte 2 is h_dest[ETH_HLEN-3] aka h_dest[3].

The sja1105_meta_unpack() function decodes these the other way around,
so a frame with MAC DA 01:80:c2:11:22:33 is received by the network
stack as having 01:80:c2:22:11:33.

Fixes: e53e18a6fe4d ("net: dsa: sja1105: Receive and decode meta frames")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: fix source port decoding in vlan_filtering=0 bridge mode

There was a regression introduced by the blamed commit, where pinging to
a VLAN-unaware bridge would fail with the repeated message "Couldn't
decode source port" coming from the tagging protocol driver.

When receiving packets with a bridge_vid as determined by
dsa_tag_8021q_bridge_join(), dsa_8021q_rcv() will decode:
- source_port = 0 (which isn't really valid, more like "don't know")
- switch_id = 0 (which isn't really valid, more like "don't know")
- vbid = value in range 1-7

Since the blamed patch has reversed the order of the checks, we are now
going to believe that source_port != -1 and switch_id != -1, so they're
valid, but they aren't.

The minimal solution to the problem is to only populate source_port and
switch_id with what dsa_8021q_rcv() came up with, if the vbid is zero,
i.e. the source port information is trustworthy.

Fixes: c1ae02d87689 ("net: dsa: tag_sja1105: always prefer source port information from INCL_SRCPT")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: always prefer source port information from INCL_SRCPT

Currently the sja1105 tagging protocol prefers using the source port
information from the VLAN header if that is available, falling back to
the INCL_SRCPT option if it isn't. The VLAN header is available for all
frames except for META frames initiated by the switch (containing RX
timestamps), and thus, the "if (is_link_local)" branch is practically
dead.

The tag_8021q source port identification has become more loose
("imprecise") and will report a plausible rather than exact bridge port,
when under a bridge (be it VLAN-aware or VLAN-unaware). But link-local
traffic always needs to know the precise source port. With incorrect
source port reporting, for example PTP traffic over 2 bridged ports will
all be seen on sockets opened on the first such port, which is incorrect.

Now that the tagging protocol has been changed to make link-local frames
always contain source port information, we can reverse the order of the
checks so that we always give precedence to that information (which is
always precise) in lieu of the tag_8021q VID which is only precise for a
standalone port.

Fixes: d7f9787a763f ("net: dsa: tag_8021q: add support for imprecise RX based on the VBID")
Fixes: 91495f21fcec ("net: dsa: tag_8021q: replace the SVL bridging with VLAN-unaware IVL bridging")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net: dsa: tag_sja1105: replace skb_mac_header() with vlan_eth_hdr()

This is a cosmetic patch which consolidates the code to use the helper
function offered by if_vlan.h.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: don't rely on skb_mac_header() in TX paths

skb_mac_header() will no longer be available in the TX path when
reverting commit 6d1ccff62780 ("net: reset mac header in
dev_start_xmit()"). As preparation for that, let's use
skb_vlan_eth_hdr() to get to the VLAN header instead, which assumes it's
located at skb->data (assumption which holds true here).

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: move tag_8021q headers to their proper place

tag_8021q definitions are all over the place. Some are exported to
linux/dsa/8021q.h (visible by DSA core, taggers, switch drivers and
everyone else), and some are in dsa_priv.h.

Move the structures that don't need external visibility into tag_8021q.c,
and the ones which don't need the world or switch drivers to see them
into tag_8021q.h.

We also have the tag_8021q.h inclusion from switch.c, which is basically
the entire reason why tag_8021q.c was built into DSA in commit
8b6e638b4be2 ("net: dsa: build tag_8021q.c as part of DSA core").
I still don't know how to better deal with that, so leave it alone.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: dsa: move tagging protocol code to tag.{c,h}

It would be nice if tagging protocol drivers could include just the
header they need, since they are (mostly) data path and isolated from
most of the other DSA core code does.

Create a tag.c and a tag.h file which are meant to support tagging
protocol drivers.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: dsa: provide a second modalias to tag proto drivers based on their name

Currently, tagging protocol drivers have a modalias of
"dsa_tag:id-<number>", where the number is one of DSA_TAG_PROTO_*_VALUE.

This modalias makes it possible for the request_module() call in
dsa_tag_driver_get() to work, given the input it has - an integer
returned by ds->ops->get_tag_protocol().

It is also possible to change tagging protocols at (pseudo-)runtime, via
sysfs or via device tree, and this works via the name string of the
tagging protocol rather than via its id (DSA_TAG_PROTO_*_VALUE).

In the latter case, there is no request_module() call, because there is
no association that the DSA core has between the string name and the ID,
to construct the modalias. The module is simply assumed to have been
inserted. This is actually slightly problematic when the tagging
protocol change should take place at probe time, since it's expected
that the dependency module should get autoloaded.

For this purpose, let's introduce a second modalias, so that the DSA
core can call request_module() by name. There is no reason to make the
modalias by name optional, so just modify the MODULE_ALIAS_DSA_TAG_DRIVER()
macro to take both the ID and the name as arguments, and generate two
modaliases behind the scenes.

Suggested-by: Michael Walle <michael@walle.cc>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Michael Walle <michael@walle.cc> # on kontron-sl28 w/ ocelot_8021q
Tested-by: Michael Walle <michael@walle.cc>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: dsa: sja1105: Check return value

Return NULL if we got unexpected value from skb_trim_rcsum() in
sja1110_rcv_inband_control_extension()

Fixes: 4913b8ebf8a9 ("net: dsa: add support for the SJA1110 native tagging protocol")
Signed-off-by: Artem Chernyshev <artem.chernyshev@red-soft.ru>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20221201140032.26746-3-artem.chernyshev@red-soft.ru
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: dsa: tag_8021q: rename dsa_8021q_bridge_tx_fwd_offload_vid

The dsa_8021q_bridge_tx_fwd_offload_vid is no longer used just for
bridge TX forwarding offload, it is the private VLAN reserved for
VLAN-unaware bridging in a way that is compatible with FDB isolation.

So just rename it dsa_tag_8021q_bridge_vid.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_8021q: merge RX and TX VLANs

In the old Shared VLAN Learning mode of operation that tag_8021q
previously used for forwarding, we needed to have distinct concepts for
an RX and a TX VLAN.

An RX VLAN could be installed on all ports that were members of a given
bridge, so that autonomous forwarding could still work, while a TX VLAN
was dedicated for precise packet steering, so it just contained the CPU
port and one egress port.

Now that tag_8021q uses Independent VLAN Learning and imprecise RX/TX
all over, those lines have been blurred and we no longer have the need
to do precise TX towards a port that is in a bridge. As for standalone
ports, it is fine to use the same VLAN ID for both RX and TX.

This patch changes the tag_8021q format by shifting the VLAN range it
reserves, and halving it. Previously, our DIR bits were encoding the
VLAN direction (RX/TX) and were set to either 1 or 2. This meant that
tag_8021q reserved 2K VLANs, or 50% of the available range.

Change the DIR bits to a hardcoded value of 3 now, which makes tag_8021q
reserve only 1K VLANs, and a different range now (the last 1K). This is
done so that we leave the old format in place in case we need to return
to it.

In terms of code, the vid_is_dsa_8021q_rxvlan and vid_is_dsa_8021q_txvlan
functions go away. Any vid_is_dsa_8021q is both a TX and an RX VLAN, and
they are no longer distinct. For example, felix which did different
things for different VLAN types, now needs to handle the RX and the TX
logic for the same VLAN.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_8021q: add support for imprecise RX based on the VBID

The sja1105 switch can't populate the PORT field of the tag_8021q header
when sending a frame to the CPU with a non-zero VBID.

Similar to dsa_find_designated_bridge_port_by_vid() which performs
imprecise RX for VLAN-aware bridges, let's introduce a helper in
tag_8021q for performing imprecise RX based on the VLAN that it has
allocated for a VLAN-unaware bridge.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: make tagging protocols connect to individual switches from a tree

On the NXP Bluebox 3 board which uses a multi-switch setup with sja1105,
the mechanism through which the tagger connects to the switch tree is
broken, due to improper DSA code design. At the time when tag_ops->connect()
is called in dsa_port_parse_cpu(), DSA hasn't finished "touching" all
the ports, so it doesn't know how large the tree is and how many ports
it has. It has just seen the first CPU port by this time. As a result,
this function will call the tagger's ->connect method too early, and the
tagger will connect only to the first switch from the tree.

This could be perhaps addressed a bit more simply by just moving the
tag_ops->connect(dst) call a bit later (for example in dsa_tree_setup),
but there is already a design inconsistency at present: on the switch
side, the notification is on a per-switch basis, but on the tagger side,
it is on a per-tree basis. Furthermore, the persistent storage itself is
per switch (ds->tagger_data). And the tagger connect and disconnect
procedures (at least the ones that exist currently) could see a fair bit
of simplification if they didn't have to iterate through the switches of
a tree.

To fix the issue, this change transforms tag_ops->connect(dst) into
tag_ops->connect(ds) and moves it somewhere where we already iterate
over all switches of a tree. That is in dsa_switch_setup_tag_protocol(),
which is a good placement because we already have there the connection
call to the switch side of things.

As for the dsa_tree_bind_tag_proto() method (called from the code path
that changes the tag protocol), things are a bit more complicated
because we receive the tree as argument, yet when we unwind on errors,
it would be nice to not call tag_ops->disconnect(ds) where we didn't
previously call tag_ops->connect(ds). We didn't have this problem before
because the tag_ops connection operations passed the entire dst before,
and this is more fine grained now. To solve the error rewind case using
the new API, we have to create yet one more cross-chip notifier for
disconnection, and stay connected with the old tag protocol to all the
switches in the tree until we've succeeded to connect with the new one
as well. So if something fails half way, the whole tree is still
connected to the old tagger. But there may still be leaks if the tagger
fails to connect to the 2nd out of 3 switches in a tree: somebody needs
to tell the tagger to disconnect from the first switch. Nothing comes
for free, and this was previously handled privately by the tagging
protocol driver before, but now we need to emit a disconnect cross-chip
notifier for that, because DSA has to take care of the unwind path. We
assume that the tagging protocol has connected to a switch if it has set
ds->tagger_data to something, otherwise we avoid calling its
disconnection method in the error rewind path.

The rest of the changes are in the tagging protocol drivers, and have to
do with the replacement of dst with ds. The iteration is removed and the
error unwind path is simplified, as mentioned above.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: fix zeroization of ds->priv on tag proto disconnect

The method was meant to zeroize ds->tagger_data but got the wrong
pointer. Fix this.

Fixes: c79e84866d2a ("net: dsa: tag_sja1105: convert to tagger-owned data")
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: dsa: tag_sja1105: split sja1105_tagger_data into private and public sections

The sja1105 driver messes with the tagging protocol's state when PTP RX
timestamping is enabled/disabled. This is fundamentally necessary
because the tagger needs to know what to do when it receives a PTP
packet. If RX timestamping is enabled, then a metadata follow-up frame
is expected, and this holds the (partial) timestamp. So the tagger plays
hide-and-seek with the network stack until it also gets the metadata
frame, and then presents a single packet, the timestamped PTP packet.
But when RX timestamping isn't enabled, there is no metadata frame
expected, so the hide-and-seek game must be turned off and the packet
must be delivered right away to the network stack.

Considering this, we create a pseudo isolation by devising two tagger
methods callable by the switch: one to get the RX timestamping state,
and one to set it. Since we can't export symbols between the tagger and
the switch driver, these methods are exposed through function pointers.

After this change, the public portion of the sja1105_tagger_data
contains only function pointers.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Revert "net: dsa: move sja1110_process_meta_tstamp inside the tagging protocol driver"

This reverts commit 6d709cadfde68dbd12bef12fcced6222226dcb06.

The above change was done to avoid calling symbols exported by the
switch driver from the tagging protocol driver.

With the tagger-owned storage model, we have a new option on our hands,
and that is for the switch driver to provide a data consumer handler in
the form of a function pointer inside the ->connect_tag_protocol()
method. Having a function pointer avoids the problems of the exported
symbols approach.

By creating a handler for metadata frames holding TX timestamps on
SJA1110, we are able to eliminate an skb queue from the tagger data, and
replace it with a simple, and stateless, function pointer. This skb
queue is now handled exclusively by sja1105_ptp.c, which makes the code
easier to follow, as it used to be before the reverted patch.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: convert to tagger-owned data

Currently, struct sja1105_tagger_data is a part of struct
sja1105_private, and is used by the sja1105 driver to populate dp->priv.

With the movement towards tagger-owned storage, the sja1105 driver
should not be the owner of this memory.

This change implements the connection between the sja1105 switch driver
and its tagging protocol, which means that sja1105_tagger_data no longer
stays in dp->priv but in ds->tagger_data, and that the sja1105 driver
now only populates the sja1105_port_deferred_xmit callback pointer.
The kthread worker is now the responsibility of the tagger.

The sja1105 driver also alters the tagger's state some more, especially
with regard to the PTP RX timestamping state. This will be fixed up a
bit in further changes.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: make dp->priv point directly to sja1105_tagger_data

The design of the sja1105 tagger dp->priv is that each port has a
separate struct sja1105_port, and the sp->data pointer points to a
common struct sja1105_tagger_data.

We have removed all per-port members accessible by the tagger, and now
only struct sja1105_tagger_data remains. Make dp->priv point directly to
this.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: bring deferred xmit implementation in line with ocelot-8021q

When the ocelot-8021q driver was converted to deferred xmit as part of
commit 8d5f7954b7c8 ("net: dsa: felix: break at first CPU port during
init and teardown"), the deferred implementation was deliberately made
subtly different from what sja1105 has.

The implementation differences lied on the following observations:

- There might be a race between these two lines in tag_sja1105.c:

skb_queue_tail(&sp->xmit_queue, skb_get(skb));
kthread_queue_work(sp->xmit_worker, &sp->xmit_work);

and the skb dequeue logic in sja1105_port_deferred_xmit(). For
example, the xmit_work might be already queued, however the work item
has just finished walking through the skb queue. Because we don't
check the return code from kthread_queue_work, we don't do anything if
the work item is already queued.

However, nobody will take that skb and send it, at least until the
next timestampable skb is sent. This creates additional (and
avoidable) TX timestamping latency.

To close that race, what the ocelot-8021q driver does is it doesn't
keep a single work item per port, and a skb timestamping queue, but
rather dynamically allocates a work item per packet.

- It is also unnecessary to have more than one kthread that does the
work. So delete the per-port kthread allocations and replace them with
a single kthread which is global to the switch.

This change brings the two implementations in line by applying those
observations to the sja1105 driver as well.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: hide dp->bridge_dev and dp->bridge_num in the core behind helpers

The location of the bridge device pointer and number is going to change.
It is not going to be kept individually per port, but in a common
structure allocated dynamically and which will have lockdep validation.

Create helpers to access these elements so that we have a migration path
to the new organization.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: dsa: tag_8021q: make dsa_8021q_{rx,tx}_vid take dp as argument

Pass a single argument to dsa_8021q_rx_vid and dsa_8021q_tx_vid that
contains the necessary information from the two arguments that are
currently provided: the switch and the port number.

Also rename those functions so that they have a dsa_port_* prefix, since
they operate on a struct dsa_port *.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: do not open-code dsa_switch_for_each_port

Find the remaining iterators over dst->ports that only filter for the
ports belonging to a certain switch, and replace those with the
dsa_switch_for_each_port helper that we have now.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: move sja1110_process_meta_tstamp inside the tagging protocol driver

The problem is that DSA tagging protocols really must not depend on the
switch driver, because this creates a circular dependency at insmod
time, and the switch driver will effectively not load when the tagging
protocol driver is missing.

The code was structured in the way it was for a reason, though. The DSA
driver-facing API for PTP timestamping relies on the assumption that
two-step TX timestamps are provided by the hardware in an out-of-band
manner, typically by raising an interrupt and making that timestamp
available inside some sort of FIFO which is to be accessed over
SPI/MDIO/etc.

So the API puts .port_txtstamp into dsa_switch_ops, because it is
expected that the switch driver needs to save some state (like put the
skb into a queue until its TX timestamp arrives).

On SJA1110, TX timestamps are provided by the switch as Ethernet
packets, so this makes them be received and processed by the tagging
protocol driver. This in itself is great, because the timestamps are
full 64-bit and do not require reconstruction, and since Ethernet is the
fastest I/O method available to/from the switch, PTP timestamps arrive
very quickly, no matter how bottlenecked the SPI connection is, because
SPI interaction is not needed at all.

DSA's code structure and strict isolation between the tagging protocol
driver and the switch driver break the natural code organization.

When the tagging protocol driver receives a packet which is classified
as a metadata packet containing timestamps, it passes those timestamps
one by one to the switch driver, which then proceeds to compare them
based on the recorded timestamp ID that was generated in .port_txtstamp.

The communication between the tagging protocol and the switch driver is
done through a method exported by the switch driver, sja1110_process_meta_tstamp.
To satisfy build requirements, we force a dependency to build the
tagging protocol driver as a module when the switch driver is a module.
However, as explained in the first paragraph, that causes the circular
dependency.

To solve this, move the skb queue from struct sja1105_private :: struct
sja1105_ptp_data to struct sja1105_private :: struct sja1105_tagger_data.
The latter is a data structure for which hacks have already been put
into place to be able to create persistent storage per switch that is
accessible from the tagging protocol driver (see sja1105_setup_ports).

With the skb queue directly accessible from the tagging protocol driver,
we can now move sja1110_process_meta_tstamp into the tagging driver
itself, and avoid exporting a symbol.

Fixes: 566b18c8b752 ("net: dsa: sja1105: implement TX timestamping for SJA1110")
Link: https://lore.kernel.org/netdev/20210908220834.d7gmtnwrorhharna@skbuf/
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: move sja1110_process_meta_tstamp inside the tagging protocol driver

The problem is that DSA tagging protocols really must not depend on the
switch driver, because this creates a circular dependency at insmod
time, and the switch driver will effectively not load when the tagging
protocol driver is missing.

The code was structured in the way it was for a reason, though. The DSA
driver-facing API for PTP timestamping relies on the assumption that
two-step TX timestamps are provided by the hardware in an out-of-band
manner, typically by raising an interrupt and making that timestamp
available inside some sort of FIFO which is to be accessed over
SPI/MDIO/etc.

So the API puts .port_txtstamp into dsa_switch_ops, because it is
expected that the switch driver needs to save some state (like put the
skb into a queue until its TX timestamp arrives).

On SJA1110, TX timestamps are provided by the switch as Ethernet
packets, so this makes them be received and processed by the tagging
protocol driver. This in itself is great, because the timestamps are
full 64-bit and do not require reconstruction, and since Ethernet is the
fastest I/O method available to/from the switch, PTP timestamps arrive
very quickly, no matter how bottlenecked the SPI connection is, because
SPI interaction is not needed at all.

DSA's code structure and strict isolation between the tagging protocol
driver and the switch driver break the natural code organization.

When the tagging protocol driver receives a packet which is classified
as a metadata packet containing timestamps, it passes those timestamps
one by one to the switch driver, which then proceeds to compare them
based on the recorded timestamp ID that was generated in .port_txtstamp.

The communication between the tagging protocol and the switch driver is
done through a method exported by the switch driver, sja1110_process_meta_tstamp.
To satisfy build requirements, we force a dependency to build the
tagging protocol driver as a module when the switch driver is a module.
However, as explained in the first paragraph, that causes the circular
dependency.

To solve this, move the skb queue from struct sja1105_private :: struct
sja1105_ptp_data to struct sja1105_private :: struct sja1105_tagger_data.
The latter is a data structure for which hacks have already been put
into place to be able to create persistent storage per switch that is
accessible from the tagging protocol driver (see sja1105_setup_ports).

With the skb queue directly accessible from the tagging protocol driver,
we can now move sja1110_process_meta_tstamp into the tagging driver
itself, and avoid exporting a symbol.

Fixes: 566b18c8b752 ("net: dsa: sja1105: implement TX timestamping for SJA1110")
Link: https://lore.kernel.org/netdev/20210908220834.d7gmtnwrorhharna@skbuf/
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: dsa: tag_sja1105: stop asking the sja1105 driver in sja1105_xmit_tpid

Introduced in commit 38b5beeae7a4 ("net: dsa: sja1105: prepare tagger
for handling DSA tags and VLAN simultaneously"), the sja1105_xmit_tpid
function solved quite a different problem than our needs are now.

Then, we used best-effort VLAN filtering and we were using the xmit_tpid
to tunnel packets coming from an 8021q upper through the TX VLAN allocated
by tag_8021q to that egress port. The need for a different VLAN protocol
depending on switch revision came from the fact that this in itself was
more of a hack to trick the hardware into accepting tunneled VLANs in
the first place.

Right now, we deny 8021q uppers (see sja1105_prechangeupper). Even if we
supported them again, we would not do that using the same method of
{tunneling the VLAN on egress, retagging the VLAN on ingress} that we
had in the best-effort VLAN filtering mode. It seems rather simpler that
we just allocate a VLAN in the VLAN table that is simply not used by the
bridge at all, or by any other port.

Anyway, I have 2 gripes with the current sja1105_xmit_tpid:

1. When sending packets on behalf of a VLAN-aware bridge (with the new
TX forwarding offload framework) plus untagged (with the tag_8021q
VLAN added by the tagger) packets, we can see that on SJA1105P/Q/R/S
and later (which have a qinq_tpid of ETH_P_8021AD), some packets sent
through the DSA master have a VLAN protocol of 0x8100 and others of
0x88a8. This is strange and there is no reason for it now. If we have
a bridge and are therefore forced to send using that bridge's TPID,
we can as well blend with that bridge's VLAN protocol for all packets.

2. The sja1105_xmit_tpid introduces a dependency on the sja1105 driver,
because it looks inside dp->priv. It is desirable to keep as much
separation between taggers and switch drivers as possible. Now it
doesn't do that anymore.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: drop untagged packets on the CPU and DSA ports

The sja1105 driver is a bit special in its use of VLAN headers as DSA
tags. This is because in VLAN-aware mode, the VLAN headers use an actual
TPID of 0x8100, which is understood even by the DSA master as an actual
VLAN header.

Furthermore, control packets such as PTP and STP are transmitted with no
VLAN header as a DSA tag, because, depending on switch generation, there
are ways to steer these control packets towards a precise egress port
other than VLAN tags. Transmitting control packets as untagged means
leaving a door open for traffic in general to be transmitted as untagged
from the DSA master, and for it to traverse the switch and exit a random
switch port according to the FDB lookup.

This behavior is a bit out of line with other DSA drivers which have
native support for DSA tagging. There, it is to be expected that the
switch only accepts DSA-tagged packets on its CPU port, dropping
everything that does not match this pattern.

We perhaps rely a bit too much on the switches' hardware dropping on the
CPU port, and place no other restrictions in the kernel data path to
avoid that. For example, sja1105 is also a bit special in that STP/PTP
packets are transmitted using "management routes"
(sja1105_port_deferred_xmit): when sending a link-local packet from the
CPU, we must first write a SPI message to the switch to tell it to
expect a packet towards multicast MAC DA 01-80-c2-00-00-0e, and to route
it towards port 3 when it gets it. This entry expires as soon as it
matches a packet received by the switch, and it needs to be reinstalled
for the next packet etc. All in all quite a ghetto mechanism, but it is
all that the sja1105 switches offer for injecting a control packet.
The driver takes a mutex for serializing control packets and making the
pairs of SPI writes of a management route and its associated skb atomic,
but to be honest, a mutex is only relevant as long as all parties agree
to take it. With the DSA design, it is possible to open an AF_PACKET
socket on the DSA master net device, and blast packets towards
01-80-c2-00-00-0e, and whatever locking the DSA switch driver might use,
it all goes kaput because management routes installed by the driver will
match skbs sent by the DSA master, and not skbs generated by the driver
itself. So they will end up being routed on the wrong port.

So through the lens of that, maybe it would make sense to avoid that
from happening by doing something in the network stack, like: introduce
a new bit in struct sk_buff, like xmit_from_dsa. Then, somewhere around
dev_hard_start_xmit(), introduce the following check:

if (netdev_uses_dsa(dev) && !skb->xmit_from_dsa)
kfree_skb(skb);

Ok, maybe that is a bit drastic, but that would at least prevent a bunch
of problems. For example, right now, even though the majority of DSA
switches drop packets without DSA tags sent by the DSA master (and
therefore the majority of garbage that user space daemons like avahi and
udhcpcd and friends create), it is still conceivable that an aggressive
user space program can open an AF_PACKET socket and inject a spoofed DSA
tag directly on the DSA master. We have no protection against that; the
packet will be understood by the switch and be routed wherever user
space says. Furthermore: there are some DSA switches where we even have
register access over Ethernet, using DSA tags. So even user space
drivers are possible in this way. This is a huge hole.

However, the biggest thing that bothers me is that udhcpcd attempts to
ask for an IP address on all interfaces by default, and with sja1105, it
will attempt to get a valid IP address on both the DSA master as well as
on sja1105 switch ports themselves. So with IP addresses in the same
subnet on multiple interfaces, the routing table will be messed up and
the system will be unusable for traffic until it is configured manually
to not ask for an IP address on the DSA master itself.

It turns out that it is possible to avoid that in the sja1105 driver, at
least very superficially, by requesting the switch to drop VLAN-untagged
packets on the CPU port. With the exception of control packets, all
traffic originated from tag_sja1105.c is already VLAN-tagged, so only
STP and PTP packets need to be converted. For that, we need to uphold
the equivalence between an untagged and a pvid-tagged packet, and to
remember that the CPU port of sja1105 uses a pvid of 4095.

Now that we drop untagged traffic on the CPU port, non-aggressive user
space applications like udhcpcd stop bothering us, and sja1105 effectively
becomes just as vulnerable to the aggressive kind of user space programs
as other DSA switches are (ok, users can also create 8021q uppers on top
of the DSA master in the case of sja1105, but in future patches we can
easily deny that, but it still doesn't change the fact that VLAN-tagged
packets can still be injected over raw sockets).

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: be dsa_loop-safe

Add support for tag_sja1105 running on non-sja1105 DSA ports, by making
sure that every time we dereference dp->priv, we check the switch's
dsa_switch_ops (otherwise we access a struct sja1105_port structure that
is in fact something else).

This adds an unconditional build-time dependency between sja1105 being
built as module => tag_sja1105 must also be built as module. This was
there only for PTP before.

Some sane defaults must also take place when not running on sja1105
hardware. These are:

- sja1105_xmit_tpid: the sja1105 driver uses different VLAN protocols
depending on VLAN awareness and switch revision (when an encapsulated
VLAN must be sent). Default to 0x8100.

- sja1105_rcv_meta_state_machine: this aggregates PTP frames with their
metadata timestamp frames. When running on non-sja1105 hardware, don't
do that and accept all frames unmodified.

- sja1105_defer_xmit: calls sja1105_port_deferred_xmit in sja1105_main.c
which writes a management route over SPI. When not running on sja1105
hardware, bypass the SPI write and send the frame as-is.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: create a helper for locating EtherType DSA headers on TX

Create a similar helper for locating the offset to the DSA header
relative to skb->data, and make the existing EtherType header taggers to
use it.

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

net: dsa: create a helper for locating EtherType DSA headers on RX

It seems that protocol tagging driver writers are always surprised about
the formula they use to reach their EtherType header on RX, which
becomes apparent from the fact that there are comments in multiple
drivers that mention the same information.

Create a helper that returns a void pointer to skb->data - 2, as well as
centralize the explanation why that is the case.

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

net: dsa: create a helper which allocates space for EtherType DSA headers

Hide away the memmove used by DSA EtherType header taggers to shift the
MAC SA and DA to the left to make room for the header, after they've
called skb_push(). The call to skb_push() is still left explicit in
drivers, to be symmetric with dsa_strip_etype_header, and because not
all callers can be refactored to do it (for example, brcm_tag_xmit_ll
has common code for a pre-Ethernet DSA tag and an EtherType DSA tag).

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

net: dsa: create a helper that strips EtherType DSA headers on RX

All header taggers open-code a memmove that is fairly not all that
obvious, and we can hide the details behind a helper function, since the
only thing specific to the driver is the length of the header tag.

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

net: dsa: tag_sja1105: consistently fail with arbitrary input

Dan Carpenter's smatch tests report that the "vid" variable, populated
by sja1105_vlan_rcv when an skb is received by the tagger that has a
VLAN ID which cannot be decoded by tag_8021q, may be uninitialized when
used here:

if (source_port == -1 || switch_id == -1)
skb->dev = dsa_find_designated_bridge_port_by_vid(netdev, vid);

The sja1105 driver, by construction, sets up the switch in a way that
all data plane packets sent towards the CPU port are VLAN-tagged. So it
is practically impossible, in a functional system, for a packet to be
processed by sja1110_rcv() which is not a control packet and does not
have a VLAN header either.

However, it would be nice if the sja1105 tagging driver could
consistently do something valid, for example fail, even if presented with
packets that do not hold valid sja1105 tags. Currently it is a bit hard
to argue that it does that, given the fact that a data plane packet with
no VLAN tag will trigger a call to dsa_find_designated_bridge_port_by_vid
with a vid argument that is an uninitialized stack variable.

To fix this, we can initialize the u16 vid variable with 0, a value that
can never be a bridge VLAN, so dsa_find_designated_bridge_port_by_vid
will always return a NULL skb->dev.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20210802195137.303625-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net: dsa: remove the struct packet_type argument from dsa_device_ops::rcv()

No tagging driver uses this.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: don't set skb->offload_fwd_mark when not offloading the bridge

DSA has gained the recent ability to deal gracefully with upper
interfaces it cannot offload, such as the bridge, bonding or team
drivers. When such uppers exist, the ports are still in standalone mode
as far as the hardware is concerned.

But when we deliver packets to the software bridge in order for that to
do the forwarding, there is an unpleasant surprise in that the bridge
will refuse to forward them. This is because we unconditionally set
skb->offload_fwd_mark = true, meaning that the bridge thinks the frames
were already forwarded in hardware by us.

Since dp->bridge_dev is populated only when there is hardware offload
for it, but not in the software fallback case, let's introduce a new
helper that can be called from the tagger data path which sets the
skb->offload_fwd_mark accordingly to zero when there is no hardware
offload for bridging. This lets the bridge forward packets back to other
interfaces of our switch, if needed.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Tobias Waldekranz <tobias@waldekranz.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: fix control packets on SJA1110 being received on an imprecise port

On RX, a control packet with SJA1110 will have:
- an in-band control extension (DSA tag) composed of a header and an
optional trailer (if it is a timestamp frame). We can (and do) deduce
the source port and switch id from this.
- a VLAN header, which can either be the tag_8021q RX VLAN (pvid) or the
bridge VLAN. The sja1105_vlan_rcv() function attempts to deduce the
source port and switch id a second time from this.

The basic idea is that even though we don't need the source port
information from the tag_8021q header if it's a control packet, we do
need to strip that header before we pass it on to the network stack.

The problem is that we call sja1105_vlan_rcv for ports under VLAN-aware
bridges, and that function tells us it couldn't identify a tag_8021q
header, so we need to perform imprecise RX by VID. Well, we don't,
because we already know the source port and switch ID.

This patch drops the return value from sja1105_vlan_rcv and we just look
at the source_port and switch_id values from sja1105_rcv and sja1110_rcv
which were initialized to -1. If they are still -1 it means we need to
perform imprecise RX.

Fixes: 884be12f8566 ("net: dsa: sja1105: add support for imprecise RX")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: add bridge TX data plane offload based on tag_8021q

The main desire for having this feature in sja1105 is to support network
stack termination for traffic coming from a VLAN-aware bridge.

For sja1105, offloading the bridge data plane means sending packets
as-is, with the proper VLAN tag, to the chip. The chip will look up its
FDB and forward them to the correct destination port.

But we support bridge data plane offload even for VLAN-unaware bridges,
and the implementation there is different. In fact, VLAN-unaware
bridging is governed by tag_8021q, so it makes sense to have the
.bridge_fwd_offload_add() implementation fully within tag_8021q.
The key difference is that we only support 1 VLAN-aware bridge, but we
support multiple VLAN-unaware bridges. So we need to make sure that the
forwarding domain is not crossed by packets injected from the stack.

For this, we introduce the concept of a tag_8021q TX VLAN for bridge
forwarding offload. As opposed to the regular TX VLANs which contain
only 2 ports (the user port and the CPU port), a bridge data plane TX
VLAN is "multicast" (or "imprecise"): it contains all the ports that are
part of a certain bridge, and the hardware will select where the packet
goes within this "imprecise" forwarding domain.

Each VLAN-unaware bridge has its own "imprecise" TX VLAN, so we make use
of the unique "bridge_num" provided by DSA for the data plane offload.
We use the same 3 bits from the tag_8021q VLAN ID format to encode this
bridge number.

Note that these 3 bit positions have been used before for sub-VLANs in
best-effort VLAN filtering mode. The difference is that for best-effort,
the sub-VLANs were only valid on RX (and it was documented that the
sub-VLAN field needed to be transmitted as zero). Whereas for the bridge
data plane offload, these 3 bits are only valid on TX.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: add support for imprecise RX

This is already common knowledge by now, but the sja1105 does not have
hardware support for DSA tagging for data plane packets, and tag_8021q
sets up a unique pvid per port, transmitted as VLAN-tagged towards the
CPU, for the source port to be decoded nonetheless.

When the port is part of a VLAN-aware bridge, the pvid committed to
hardware is taken from the bridge and not from tag_8021q, so we need to
work with that the best we can.

Configure the switches to send all packets to the CPU as VLAN-tagged
(even ones that were originally untagged on the wire) and make use of
dsa_untag_bridge_pvid() to get rid of it before we send those packets up
the network stack.

With the classified VLAN used by hardware known to the tagger, we first
peek at the VID in an attempt to figure out if the packet was received
from a VLAN-unaware port (standalone or under a VLAN-unaware bridge),
case in which we can continue to call dsa_8021q_rcv(). If that is not
the case, the packet probably came from a VLAN-aware bridge. So we call
the DSA helper that finds for us a "designated bridge port" - one that
is a member of the VLAN ID from the packet, and is in the proper STP
state - basically these are all checks performed by br_handle_frame() in
the software RX data path.

The bridge will accept the packet as valid even if the source port was
maybe wrong. So it will maybe learn the MAC SA of the packet on the
wrong port, and its software FDB will be out of sync with the hardware
FDB. So replies towards this same MAC DA will not work, because the
bridge will send towards a different netdev.

This is where the bridge data plane offload ("imprecise TX") added by
the next patch comes in handy. The software FDB is wrong, true, but the
hardware FDB isn't, and by offloading the bridge forwarding plane we
have a chance to right a wrong, and have the hardware look up the FDB
for us for the reply packet. So it all cancels out.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: delete the best_effort_vlan_filtering mode

Simply put, the best-effort VLAN filtering mode relied on VLAN retagging
from a bridge VLAN towards a tag_8021q sub-VLAN in order to be able to
decode the source port in the tagger, but the VLAN retagging
implementation inside the sja1105 chips is not the best and we were
relying on marginal operating conditions.

The most notable limitation of the best-effort VLAN filtering mode is
its incapacity to treat this case properly:

ip link add br0 type bridge vlan_filtering 1
ip link set swp2 master br0
ip link set swp4 master br0
bridge vlan del dev swp4 vid 1
bridge vlan add dev swp4 vid 1 pvid

When sending an untagged packet through swp2, the expectation is for it
to be forwarded to swp4 as egress-tagged (so it will contain VLAN ID 1
on egress). But the switch will send it as egress-untagged.

There was an attempt to fix this here:
https://patchwork.kernel.org/project/netdevbpf/patch/20210407201452.1703261-2-olteanv@gmail.com/

but it failed miserably because it broke PTP RX timestamping, in a way
that cannot be corrected due to hardware issues related to VLAN
retagging.

So with either PTP broken or pushing VLAN headers on egress for untagged
packets being broken, the sad reality is that the best-effort VLAN
filtering code is broken. Delete it.

Note that this means there will be a temporary loss of functionality in
this driver until it is replaced with something better (network stack
RX/TX capability for "mode 2" as described in
Documentation/networking/dsa/sja1105.rst, the "port under VLAN-aware
bridge" case). We simply cannot keep this code until that driver rework
is done, it is super bloated and tangled with tag_8021q.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: implement TX timestamping for SJA1110

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

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

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

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_sja1105: stop resetting network and transport headers

This makes no sense and is not needed, it is probably a debugging
leftover.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: generalize overhead for taggers that use both headers and trailers

Some really really weird switches just couldn't decide whether to use a
normal or a tail tagger, so they just did both.

This creates problems for DSA, because we only have the concept of an
'overhead' which can be applied to the headroom or to the tailroom of
the skb (like for example during the central TX reallocation procedure),
depending on the value of bool tail_tag, but not to both.

We need to generalize DSA to cater for these odd switches by
transforming the 'overhead / tail_tag' pair into 'needed_headroom /
needed_tailroom'.

The DSA master's MTU is increased to account for both.

The flow dissector code is modified such that it only calls the DSA
adjustment callback if the tagger has a non-zero header length.

Taggers are trivially modified to declare either needed_headroom or
needed_tailroom, based on the tail_tag value that they currently
declare.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: use a custom flow dissector procedure

The sja1105 is a bit of a special snowflake, in that not all frames are
transmitted/received in the same way. L2 link-local frames are received
with the source port/switch ID information put in the destination MAC
address. For the rest, a tag_8021q header is used. So only the latter
frames displace the rest of the headers and need to use the generic flow
dissector procedure.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: request promiscuous mode for master

Currently PTP is broken when ports are in standalone mode (the tagger
keeps printing this message):

sja1105 spi0.1: Expected meta frame, is 01-80-c2-00-00-0e in the DSA master multicast filter?

Sure, one might say "simply add 01-80-c2-00-00-0e to the master's RX
filter" but things become more complicated because:

- Actually all frames in the 01-80-c2-xx-xx-xx and 01-1b-19-xx-xx-xx
range are trapped to the CPU automatically
- The switch mangles bytes 3 and 4 of the MAC address via the incl_srcpt
("include source port [in the DMAC]") option, which is how source port
and switch id identification is done for link-local traffic on RX. But
this means that an address installed to the RX filter would, at the
end of the day, not correspond to the final address seen by the DSA
master.

Assume RX filtering lists on DSA masters are typically too small to
include all necessary addresses for PTP to work properly on sja1105, and
just request promiscuous mode unconditionally.

Just an example:
Assuming the following addresses are trapped to the CPU:
01-80-c2-00-00-00 to 01-80-c2-00-00-ff
01-1b-19-00-00-00 to 01-1b-19-00-00-ff

These are 512 addresses.
Now let's say this is a board with 3 switches, and 4 ports per switch.
The 512 addresses become 6144 addresses that must be managed by the DSA
master's RX filtering lists.

This may be refined in the future, but for now, it is simply not worth
it to add the additional addresses to the master's RX filter, so simply
request it to become promiscuous as soon as the driver probes.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: add compatibility with hwaccel VLAN tags

Check whether there is any hwaccel VLAN tag on RX, and if there is,
treat it as the tag_8021q header.

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: dsa: tag_sja1105: appease sparse checks for ethertype accessors

A comparison between a value from the packet and an integer constant
value needs to be done by converting the value from the packet from
net->host, or the constant from host->net. Not the other way around.
Even though it makes no practical difference, correct that.

Fixes: 38b5beeae7a4 ("net: dsa: sja1105: prepare tagger for handling DSA tags and VLAN simultaneously")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: implement sub-VLAN decoding

Create a subvlan_map as part of each port's tagger private structure.
This keeps reverse mappings of bridge-to-dsa_8021q VLAN retagging rules.

Note that as of this patch, this piece of code is never engaged, due to
the fact that the driver hasn't installed any retagging rule, so we'll
always see packets with a subvlan code of 0 (untagged).

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: dsa: sja1105: prepare tagger for handling DSA tags and VLAN simultaneously

In VLAN-unaware mode, sja1105 uses VLAN tags with a custom TPID of
0xdadb. While in the yet-to-be introduced best_effort_vlan_filtering
mode, it needs to work with normal VLAN TPID values.

A complication arises when we must transmit a VLAN-tagged packet to the
switch when it's in VLAN-aware mode. We need to construct a packet with
2 VLAN tags, and the switch will use the outer header for routing and
pop it on egress. But sadly, here the 2 hardware generations don't
behave the same:

- E/T switches won't pop an ETH_P_8021AD tag on egress, it seems
(packets will remain double-tagged).
- P/Q/R/S switches will drop a packet with 2 ETH_P_8021Q tags (it looks
like it tries to prevent VLAN hopping).

But looks like the reverse is also true:

- E/T switches have no problem popping the outer tag from packets with
2 ETH_P_8021Q tags.
- P/Q/R/S will have no problem popping a single tag even if that is
ETH_P_8021AD.

So it is clear that if we want the hardware to work with dsa_8021q
tagging in VLAN-aware mode, we need to send different TPIDs depending on
revision. Keep that information in priv->info->qinq_tpid.

The per-port tagger structure will hold an xmit_tpid value that depends
not only upon the qinq_tpid, but also upon the VLAN awareness state
itself (in case we must transmit using 0xdadb).

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: dsa: tag_sja1105: Constify dsa_device_ops

sja1105_netdev_ops should be const since that is what the DSA layer
expects.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_8021q: replace dsa_8021q_remove_header with __skb_vlan_pop

Not only did this wheel did not need reinventing, but there is also
an issue with it: It doesn't remove the VLAN header in a way that
preserves the L2 payload checksum when that is being provided by the DSA
master hw. It should recalculate checksum both for the push, before
removing the header, and for the pull afterwards. But the current
implementation is quite dizzying, with pulls followed immediately
afterwards by pushes, the memmove is done before the push, etc. This
makes a DSA master with RX checksumming offload to print stack traces
with the infamous 'hw csum failure' message.

So remove the dsa_8021q_remove_header function and replace it with
something that actually works with inet checksumming.

Fixes: d461933638ae ("net: dsa: tag_8021q: Create helper function for removing VLAN header")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: tag_sja1105: Slightly improve the Xmas tree in sja1105_xmit

This is a cosmetic patch that makes the dp, tx_vid, queue_mapping and
pcp local variable definitions a bit closer in length, so they don't
look like an eyesore as much.

The 'ds' variable is not used otherwise, except for ds->dp.

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>

net: dsa: Make deferred_xmit private to sja1105

There are 3 things that are wrong with the DSA deferred xmit mechanism:

1. Its introduction has made the DSA hotpath ever so slightly more
inefficient for everybody, since DSA_SKB_CB(skb)->deferred_xmit needs
to be initialized to false for every transmitted frame, in order to
figure out whether the driver requested deferral or not (a very rare
occasion, rare even for the only driver that does use this mechanism:
sja1105). That was necessary to avoid kfree_skb from freeing the skb.

2. Because L2 PTP is a link-local protocol like STP, it requires
management routes and deferred xmit with this switch. But as opposed
to STP, the deferred work mechanism needs to schedule the packet
rather quickly for the TX timstamp to be collected in time and sent
to user space. But there is no provision for controlling the
scheduling priority of this deferred xmit workqueue. Too bad this is
a rather specific requirement for a feature that nobody else uses
(more below).

3. Perhaps most importantly, it makes the DSA core adhere a bit too
much to the NXP company-wide policy "Innovate Where It Doesn't
Matter". The sja1105 is probably the only DSA switch that requires
some frames sent from the CPU to be routed to the slave port via an
out-of-band configuration (register write) rather than in-band (DSA
tag). And there are indeed very good reasons to not want to do that:
if that out-of-band register is at the other end of a slow bus such
as SPI, then you limit that Ethernet flow's throughput to effectively
the throughput of the SPI bus. So hardware vendors should definitely
not be encouraged to design this way. We do _not_ want more
widespread use of this mechanism.

Luckily we have a solution for each of the 3 issues:

For 1, we can just remove that variable in the skb->cb and counteract
the effect of kfree_skb with skb_get, much to the same effect. The
advantage, of course, being that anybody who doesn't use deferred xmit
doesn't need to do any extra operation in the hotpath.

For 2, we can create a kernel thread for each port's deferred xmit work.
If the user switch ports are named swp0, swp1, swp2, the kernel threads
will be named swp0_xmit, swp1_xmit, swp2_xmit (there appears to be a 15
character length limit on kernel thread names). With this, the user can
change the scheduling priority with chrt $(pidof swp2_xmit).

For 3, we can actually move the entire implementation to the sja1105
driver.

So this patch deletes the generic implementation from the DSA core and
adds a new one, more adequate to the requirements of PTP TX
timestamping, in sja1105_main.c.

Suggested-by: Florian Fainelli <f.fainelli@gmail.com>
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>

net: dsa: sja1105: Fix sleeping while atomic in .port_hwtstamp_set

Currently this stack trace can be seen with CONFIG_DEBUG_ATOMIC_SLEEP=y:

[ 41.568348] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:909
[ 41.576757] in_atomic(): 1, irqs_disabled(): 0, pid: 208, name: ptp4l
[ 41.583212] INFO: lockdep is turned off.
[ 41.587123] CPU: 1 PID: 208 Comm: ptp4l Not tainted 5.3.0-rc6-01445-ge950f2d4bc7f-dirty #1827
[ 41.599873] [<c0313d7c>] (unwind_backtrace) from [<c030e13c>] (show_stack+0x10/0x14)
[ 41.607584] [<c030e13c>] (show_stack) from [<c1212d50>] (dump_stack+0xd4/0x100)
[ 41.614863] [<c1212d50>] (dump_stack) from [<c037dfc8>] (___might_sleep+0x1c8/0x2b4)
[ 41.622574] [<c037dfc8>] (___might_sleep) from [<c122ea90>] (__mutex_lock+0x48/0xab8)
[ 41.630368] [<c122ea90>] (__mutex_lock) from [<c122f51c>] (mutex_lock_nested+0x1c/0x24)
[ 41.638340] [<c122f51c>] (mutex_lock_nested) from [<c0c6fe08>] (sja1105_static_config_reload+0x30/0x27c)
[ 41.647779] [<c0c6fe08>] (sja1105_static_config_reload) from [<c0c7015c>] (sja1105_hwtstamp_set+0x108/0x1cc)
[ 41.657562] [<c0c7015c>] (sja1105_hwtstamp_set) from [<c0feb650>] (dev_ifsioc+0x18c/0x330)
[ 41.665788] [<c0feb650>] (dev_ifsioc) from [<c0febbd8>] (dev_ioctl+0x320/0x6e8)
[ 41.673064] [<c0febbd8>] (dev_ioctl) from [<c0f8b1f4>] (sock_ioctl+0x334/0x5e8)
[ 41.680340] [<c0f8b1f4>] (sock_ioctl) from [<c05404a8>] (do_vfs_ioctl+0xb0/0xa10)
[ 41.687789] [<c05404a8>] (do_vfs_ioctl) from [<c0540e3c>] (ksys_ioctl+0x34/0x58)
[ 41.695151] [<c0540e3c>] (ksys_ioctl) from [<c0301000>] (ret_fast_syscall+0x0/0x28)
[ 41.702768] Exception stack(0xe8495fa8 to 0xe8495ff0)
[ 41.707796] 5fa0: beff4a8c 00000001 00000011 000089b0 beff4a8c beff4a80
[ 41.715933] 5fc0: beff4a8c 00000001 0000000c 00000036 b6fa98c8 004e19c1 00000001 00000000
[ 41.724069] 5fe0: 004dcedc beff4a6c 004c0738 b6e7af4c
[ 41.729860] BUG: scheduling while atomic: ptp4l/208/0x00000002
[ 41.735682] INFO: lockdep is turned off.

Enabling RX timestamping will logically disturb the fastpath (processing
of meta frames). Replace bool hwts_rx_en with a bit that is checked
atomically from the fastpath and temporarily unset from the sleepable
context during a change of the RX timestamping process (a destructive
operation anyways, requires switch reset).
If found unset, the fastpath (net/dsa/tag_sja1105.c) will just drop any
received meta frame and not take the meta_lock at all.

Fixes: a602afd200f5 ("net: dsa: sja1105: Expose PTP timestamping ioctls to userspace")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: Advertise the 8 TX queues

This is a preparation patch for the tc-taprio offload (and potentially
for other future offloads such as tc-mqprio).

Instead of looking directly at skb->priority during xmit, let's get the
netdev queue and the queue-to-traffic-class mapping, and put the
resulting traffic class into the dsa_8021q PCP field. The switch is
configured with a 1-to-1 PCP-to-ingress-queue-to-egress-queue mapping
(see vlan_pmap in sja1105_main.c), so the effect is that we can inject
into a front-panel's egress traffic class through VLAN tagging from
Linux, completely transparently.

Unfortunately the switch doesn't look at the VLAN PCP in the case of
management traffic to/from the CPU (link-local frames at
01-80-C2-xx-xx-xx or 01-1B-19-xx-xx-xx) so we can't alter the
transmission queue of this type of traffic on a frame-by-frame basis. It
is only selected through the "hostprio" setting which ATM is harcoded in
the driver to 7.

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>

net: dsa: sja1105: Fix memory leak on meta state machine error path

When RX timestamping is enabled and two link-local (non-meta) frames are
received in a row, this constitutes an error.

The tagger is always caching the last link-local frame, in an attempt to
merge it with the meta follow-up frame when that arrives. To recover
from the above error condition, the initial cached link-local frame is
dropped and the second frame in a row is cached (in expectance of the
second meta frame).

However, when dropping the initial link-local frame, its backing memory
was being leaked.

Fixes: f3097be21bf1 ("net: dsa: sja1105: Add a state machine for RX timestamping")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: Fix memory leak on meta state machine normal path

After a meta frame is received, it is associated with the cached
sp->data->stampable_skb from the DSA tagger private structure.

Cached means its refcount is incremented with skb_get() in order for
dsa_switch_rcv() to not free it when the tagger .rcv returns NULL.

The mistake is that skb_unref() is not the correct function to use. It
will correctly decrement the refcount (which will go back to zero) but
the skb memory will not be freed. That is the job of kfree_skb(), which
also calls skb_unref().

But it turns out that freeing the cached stampable_skb is in fact not
necessary. It is still a perfectly valid skb, and now it is even
annotated with the partial RX timestamp. So remove the skb_copy()
altogether and simply pass the stampable_skb with a refcount of 1
(incremented by us, decremented by dsa_switch_rcv) up the stack.

Fixes: f3097be21bf1 ("net: dsa: sja1105: Add a state machine for RX timestamping")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: Fix missing unlock on error in sk_buff()

Add the missing unlock before return from function sk_buff()
in the error handling case.

Fixes: f3097be21bf1 ("net: dsa: sja1105: Add a state machine for RX timestamping")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: Add a state machine for RX timestamping

Meta frame reception relies on the hardware keeping its promise that it
will send no other traffic towards the CPU port between a link-local
frame and a meta frame. Otherwise there is no other way to associate
the meta frame with the link-local frame it's holding a timestamp of.
The receive function is made stateful, and buffers a timestampable frame
until its meta frame arrives, then merges the two, drops the meta and
releases the link-local frame up the stack.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: Receive and decode meta frames

This adds support in the tagger for understanding the source port and
switch id of meta frames. Their timestamp is also extracted but not
used yet - this needs to be done in a state machine that modifies the
previously received timestampable frame - will be added in a follow-up
patch.

Also take the opportunity to:
- Remove a comment in sja1105_filter made obsolete by e8d67fa5696e
("net: dsa: sja1105: Don't store frame type in skb->cb")
- Reorder the checks in sja1105_filter to optimize for the most likely
scenario first: regular traffic.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: Make sja1105_is_link_local not match meta frames

Although meta frames are configured to be sent at SJA1105_META_DMAC
(01-80-C2-00-00-0E) which is a multicast MAC address that would also be
trapped by the switch to the CPU, were it to receive it on a front-panel
port, meta frames are conceptually not link-local frames, they only
carry their RX timestamps.

The choice of sending meta frames at a multicast DMAC is a pragmatic
one, to avoid installing an extra entry to the DSA master port's
multicast MAC filter.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

net: dsa: sja1105: Limit use of incl_srcpt to bridge+vlan mode

The incl_srcpt setting makes the switch mangle the destination MACs of
multicast frames trapped to the CPU - a primitive tagging mechanism that
works even when we cannot use the 802.1Q software features.

The downside is that the two multicast MAC addresses that the switch
traps for L2 PTP (01-80-C2-00-00-0E and 01-1B-19-00-00-00) quickly turn
into a lot more, as the switch encodes the source port and switch id
into bytes 3 and 4 of the MAC. The resulting range of MAC addresses
would need to be installed manually into the DSA master port's multicast
MAC filter, and even then, most devices might not have a large enough
MAC filtering table.

As a result, only limit use of incl_srcpt to when it's strictly
necessary: when under a VLAN filtering bridge. This fixes PTP in
non-bridged mode (standalone ports). Otherwise, PTP frames, as well as
metadata follow-up frames holding RX timestamps won't be received
because they will be blocked by the master port's MAC filter.
Linuxptp doesn't help, because it only requests the addition of the
unmodified PTP MACs to the multicast filter.
This issue is not seen in bridged mode because the master port is put in
promiscuous mode when the slave ports are enslaved to a bridge.
Therefore, there is no downside to having the incl_srcpt mechanism
active there.

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>

net: dsa: tag_8021q: Create helper function for removing VLAN header

This removes the existing implementation from tag_sja1105, which was
partially incorrect (it was not changing the MAC header offset, thereby
leaving it to point 4 bytes earlier than it should have).

This overwrites the VLAN tag by moving the Ethernet source and
destination MACs 4 bytes to the right. Then skb->data (assumed to be
pointing immediately after the EtherType) is temporarily pushed to the
beginning of the new Ethernet header, the new Ethernet header offset and
length are recorded, then skb->data is moved back to where it was.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: Don't store frame type in skb->cb

Due to a confusion I thought that eth_type_trans() was called by the
network stack whereas it can actually be called by network drivers to
figure out the skb protocol and next packet_type handlers.

In light of the above, it is not safe to store the frame type from the
DSA tagger's .filter callback (first entry point on RX path), since GRO
is yet to be invoked on the received traffic. Hence it is very likely
that the skb->cb will actually get overwritten between eth_type_trans()
and the actual DSA packet_type handler.

Of course, what this patch fixes is the actual overwriting of the
SJA1105_SKB_CB(skb)->type field from the GRO layer, which made all
frames be seen as SJA1105_FRAME_TYPE_NORMAL (0).

Fixes: 227d07a07ef1 ("net: dsa: sja1105: Add support for traffic through standalone ports")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net: dsa: sja1105: Add support for traffic through standalone ports

In order to support this, we are creating a make-shift switch tag out of
a VLAN trunk configured on the CPU port. Termination of normal traffic
on switch ports only works when not under a vlan_filtering bridge.
Termination of management (PTP, BPDU) traffic works under all
circumstances because it uses a different tagging mechanism
(incl_srcpt). We are making use of the generic CONFIG_NET_DSA_TAG_8021Q
code and leveraging it from our own CONFIG_NET_DSA_TAG_SJA1105.

There are two types of traffic: regular and link-local.

The link-local traffic received on the CPU port is trapped from the
switch's regular forwarding decisions because it matched one of the two
DMAC filters for management traffic.

On transmission, the switch requires special massaging for these
link-local frames. Due to a weird implementation of the switching IP, by
default it drops link-local frames that originate on the CPU port.
It needs to be told where to forward them to, through an SPI command
("management route") that is valid for only a single frame.
So when we're sending link-local traffic, we are using the
dsa_defer_xmit mechanism.

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>