net: dsa: microchip: Add partial ACL support for ksz9477 switches

This patch adds partial Access Control List (ACL) support for the
ksz9477 family of switches. ACLs enable filtering of incoming layer 2
MAC, layer 3 IP, and layer 4 TCP/UDP packets on each port. They provide
additional capabilities for filtering routed network protocols and can
take precedence over other forwarding functions.

ACLs can filter ingress traffic based on header fields such as
source/destination MAC address, EtherType, IPv4 address, IPv4 protocol,
UDP/TCP ports, and TCP flags. The ACL is an ordered list of up to 16
access control rules programmed into the ACL Table. Each entry specifies
a set of matching conditions and action rules for controlling packet
forwarding and priority.

The ACL also implements a count function, generating an interrupt
instead of a forwarding action. It can be used as a watchdog timer or an
event counter. The ACL consists of three parts: matching rules, action
rules, and processing entries. Multiple match conditions can be either
AND'ed or OR'ed together.

This patch introduces support for a subset of the available ACL
functionality, specifically layer 2 matching and prioritization of
matched packets. For example:

tc qdisc add dev lan2 clsact
tc filter add dev lan2 ingress protocol 0x88f7 flower action skbedit prio 7

tc qdisc add dev lan1 clsact
tc filter add dev lan1 ingress protocol 0x88f7 flower action skbedit prio 7

The hardware offloading implementation was benchmarked against a
configuration without hardware offloading. This latter setup relied on a
software-based Linux bridge. No noticeable differences were observed
between the two configurations. Here is an example of software-based
test:

ip l s dev enu1u1 up
ip l s dev enu1u2 up
ip l s dev enu1u4 up
ethtool -A enu1u1 autoneg off rx off tx off
ethtool -A enu1u2 autoneg off rx off tx off
ethtool -A enu1u4 autoneg off rx off tx off
ip l a name br0 type bridge
ip l s dev br0 up
ip l s enu1u1 master br0
ip l s enu1u2 master br0
ip l s enu1u4 master br0

tc qdisc add dev enu1u1 root handle 1: ets strict 4 priomap 3 3 2 2 1 1 0 0
tc qdisc add dev enu1u4 root handle 1: ets strict 4 priomap 3 3 2 2 1 1 0 0
tc qdisc add dev enu1u2 root handle 1: ets strict 4 priomap 3 3 2 2 1 1 0 0

tc qdisc add dev enu1u1 clsact
tc filter add dev enu1u1 ingress protocol ipv4 flower action skbedit prio 7

tc qdisc add dev enu1u4 clsact
tc filter add dev enu1u4 ingress protocol ipv4 flower action skbedit prio 0

On a system attached to the port enu1u2 I run two iperf3 server
instances:
iperf3 -s -p 5210 &
iperf3 -s -p 5211 &

On systems attached to enu1u4 and enu1u1 I run:
iperf3 -u -c 172.17.0.1 -p 5210 -b100M -l1472 -t100
and
iperf3 -u -c 172.17.0.1 -p 5211 -b100M -l1472 -t100

As a result, IP traffic on port enu1u1 will be prioritized and take
precedence over IP traffic on port enu1u4

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>