net: enetc: fix support for PTP_EXTTS_REQUEST2 ioctl

Commit 7c571ac57d ("net: ptp: introduce .supported_extts_flags to
ptp_clock_info") moved the validation of the external timestamp request
flags into the PTP core. A driver that does not set
.supported_extts_flags still accepts the legacy PTP_EXTTS_REQUEST ioctl,
but every PTP_EXTTS_REQUEST2 request is rejected with -EOPNOTSUPP.

The ENETC timer is the QorIQ 1588 timer, set up by ptp_qoriq_init(), which
programs TMR_CTRL with ETEP1 and ETEP2 cleared, so it timestamps the
rising edge of its external trigger inputs. Declare that, with
PTP_STRICT_FLAGS, so that a falling edge request is rejected instead of
being timestamped on the rising edge.

This also makes the legacy PTP_EXTTS_REQUEST ioctl strict: a request for
the falling edge, or for both edges, now fails with -EOPNOTSUPP instead
of being timestamped on the rising edge. That cannot be avoided: the core
adds PTP_STRICT_FLAGS to every PTP_EXTTS_REQUEST2 request, so a driver
has to declare it to accept them, and once declared it applies to both
ioctls. Commit 3200fdd402 ("broadcom: fix support for
PTP_EXTTS_REQUEST2 ioctl") made the same change for bcm-phy-ptp.

Fixes: 7c571ac57d ("net: ptp: introduce .supported_extts_flags to ptp_clock_info")
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Signed-off-by: Vincent Jardin <vjardin@free.fr>
Reviewed-by: Wei Fang <wei.fang@nxp.com>
Link: https://patch.msgid.link/20261009-for-upstream-qoriq-ptp-extts-flags-v2-2-0f4eeff2295d@free.fr
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/freescale/enetc/enetc_ptp.c

@@ -16,6 +16,7 @@ static struct ptp_clock_info enetc_ptp_caps = {
 	.n_per_out	= 0,
 	.n_pins		= 0,
 	.pps		= 1,
+	.supported_extts_flags = PTP_RISING_EDGE | PTP_STRICT_FLAGS,
 	.adjfine	= ptp_qoriq_adjfine,
 	.adjtime	= ptp_qoriq_adjtime,
 	.gettime64	= ptp_qoriq_gettime,