This patch set adds PTP timestamping support to the NETC switch, so that
the switch ports can be used for IEEE 1588 PTP synchronization.
The NETC switch has no time registers of its own and instead shares the
PTP time of the NETC Timer, which is a separate PCIe function driven by
its own driver. The first 3 patches prepare the Timer driver for this
role: tidy up its 64-bit register access, drop an ineffective reset, and
export netc_timer_get_current_time() so the switch driver can read the
current PTP time across the driver boundary in a race-free way.
The switch redirects PTP frames to the CPU through the ingress port
filter table (IPFT). A few patches harden and simplify the existing IPFT
and host flood handling first, then enable the ingress port filtering
lookup by default so PTP filter rules take effect without extra software
tracking.
On top of that groundwork, the switch driver gains RX timestamping and
both flavours of TX timestamping. Timestamps are carried between the
hardware and the driver through dedicated switch tags: the ingress and
transmit timestamps ride in To_Host tags, and per-frame requests ride in
To_Port tags. Two-step TX matches a queued skb clone against the
timestamp response echoed back by the hardware. One-step TX defers the
Sync frame to a per-port work, where the driver reads a fresh PTP time
and writes it into the Sync frame's timestamp field, then programs the
single-step register and transmits the frame so the hardware can add the
residence time to the correction field on the wire.
Together these changes let standard user-space PTP stacks drive hardware
timestamping on the NETC switch ports.
I saw netdev's Sashiko reported some issues [1], and I think some of them
should be fixed or improved.
[1] https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20261103021024.3121936-1-wei.fang%40oss.nxp.com
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