net: ptp: introduce .supported_perout_flags to ptp_clock_info

The PTP_PEROUT_REQUEST2 ioctl has gained support for flags specifying
specific output behavior including PTP_PEROUT_ONE_SHOT,
PTP_PEROUT_DUTY_CYCLE, PTP_PEROUT_PHASE.

Driver authors are notorious for not checking the flags of the request.
This results in misinterpreting the request, generating an output signal
that does not match the requested value. It is anticipated that even more
flags will be added in the future, resulting in even more broken requests.

Expecting these issues to be caught during review or playing whack-a-mole
after the fact is not a great solution.

Instead, introduce the supported_perout_flags field in the ptp_clock_info
structure. Update the core character device logic to explicitly reject any
request which has a flag not on this list.

This ensures that drivers must 'opt in' to the flags they support. Drivers
which don't set the .supported_perout_flags field will not need to check
that unsupported flags aren't passed, as the core takes care of this.

Update the drivers which do support flags to set this new field.

Note the following driver files set n_per_out to a non-zero value but did
not check the flags at all:

 • drivers/ptp/ptp_clockmatrix.c
 • drivers/ptp/ptp_idt82p33.c
 • drivers/ptp/ptp_fc3.c
 • drivers/net/ethernet/ti/am65-cpts.c
 • drivers/net/ethernet/aquantia/atlantic/aq_ptp.c
 • drivers/net/ethernet/broadcom/bnxt/bnxt_ptp.c
 • drivers/net/dsa/sja1105/sja1105_ptp.c
 • drivers/net/ethernet/freescale/dpaa2/dpaa2-ptp.c
 • drivers/net/ethernet/mscc/ocelot_vsc7514.c
 • drivers/net/ethernet/intel/i40e/i40e_ptp.c

Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20250414-jk-supported-perout-flags-v2-2-f6b17d15475c@intel.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>