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SubjectRe: [net-next, v5, 02/11] ptp: support ptp physical/virtual clocks conversion
Date
Yangbo Lu <yangbo.lu@nxp.com> writes:

> Support ptp physical/virtual clocks conversion via sysfs.
> There will be a new attribute n_vclocks under ptp physical
> clock sysfs.
>
> - In default, the value is 0 meaning only ptp physical clock
> is in use.
> - Setting the value can create corresponding number of ptp
> virtual clocks to use. But current physical clock is guaranteed
> to stay free running.
> - Setting the value back to 0 can delete virtual clocks and back
> use physical clock again.
>
> Another new attribute max_vclocks control the maximum number of
> ptp vclocks.
>
> Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
> ---
> Changes for v2:
> - Split from v1 patch #2.
> - Converted to num_vclocks for creating virtual clocks.
> - Guranteed physical clock free running when using virtual
> clocks.
> - Fixed build warning.
> - Updated copyright.
> Changes for v3:
> - Protected concurrency of ptp->num_vclocks accessing.
> Changes for v4:
> - Rephrased description in doc.
> - Used unsigned int for vclocks number, and max_vclocks
> for limitiation.
> - Fixed mutex locking.
> - Other minor fixes.
> Changes for v5:
> - Fixed checkpatch.
> - Checked pointer parent->class->name.
> ---
> Documentation/ABI/testing/sysfs-ptp | 20 ++++
> drivers/ptp/ptp_clock.c | 26 ++++++
> drivers/ptp/ptp_private.h | 21 +++++
> drivers/ptp/ptp_sysfs.c | 138 ++++++++++++++++++++++++++++
> 4 files changed, 205 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-ptp b/Documentation/ABI/testing/sysfs-ptp
> index 2363ad810ddb..d378f57c1b73 100644
> --- a/Documentation/ABI/testing/sysfs-ptp
> +++ b/Documentation/ABI/testing/sysfs-ptp
> @@ -33,6 +33,13 @@ Description:
> frequency adjustment value (a positive integer) in
> parts per billion.
>
> +What: /sys/class/ptp/ptpN/max_vclocks
> +Date: May 2021
> +Contact: Yangbo Lu <yangbo.lu@nxp.com>
> +Description:
> + This file contains the maximum number of ptp vclocks.
> + Write integer to re-configure it.
> +
> What: /sys/class/ptp/ptpN/n_alarms
> Date: September 2010
> Contact: Richard Cochran <richardcochran@gmail.com>
> @@ -61,6 +68,19 @@ Description:
> This file contains the number of programmable pins
> offered by the PTP hardware clock.
>
> +What: /sys/class/ptp/ptpN/n_vclocks
> +Date: May 2021
> +Contact: Yangbo Lu <yangbo.lu@nxp.com>
> +Description:
> + This file contains the number of virtual PTP clocks in
> + use. By default, the value is 0 meaning that only the
> + physical clock is in use. Setting the value creates
> + the corresponding number of virtual clocks and causes
> + the physical clock to become free running. Setting the
> + value back to 0 deletes the virtual clocks and
> + switches the physical clock back to normal, adjustable
> + operation.
> +
> What: /sys/class/ptp/ptpN/pins
> Date: March 2014
> Contact: Richard Cochran <richardcochran@gmail.com>
> diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
> index a23a37a4d5dc..7334f478dde7 100644
> --- a/drivers/ptp/ptp_clock.c
> +++ b/drivers/ptp/ptp_clock.c
> @@ -76,6 +76,11 @@ static int ptp_clock_settime(struct posix_clock *pc, const struct timespec64 *tp
> {
> struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
>
> + if (ptp_vclock_in_use(ptp)) {
> + pr_err("ptp: virtual clock in use\n");
> + return -EBUSY;
> + }
> +
> return ptp->info->settime64(ptp->info, tp);
> }
>
> @@ -97,6 +102,11 @@ static int ptp_clock_adjtime(struct posix_clock *pc, struct __kernel_timex *tx)
> struct ptp_clock_info *ops;
> int err = -EOPNOTSUPP;
>
> + if (ptp_vclock_in_use(ptp)) {
> + pr_err("ptp: virtual clock in use\n");
> + return -EBUSY;
> + }
> +
> ops = ptp->info;
>
> if (tx->modes & ADJ_SETOFFSET) {
> @@ -161,6 +171,7 @@ static void ptp_clock_release(struct device *dev)
> ptp_cleanup_pin_groups(ptp);
> mutex_destroy(&ptp->tsevq_mux);
> mutex_destroy(&ptp->pincfg_mux);
> + mutex_destroy(&ptp->n_vclocks_mux);
> ida_simple_remove(&ptp_clocks_map, ptp->index);
> kfree(ptp);
> }
> @@ -208,6 +219,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
> spin_lock_init(&ptp->tsevq.lock);
> mutex_init(&ptp->tsevq_mux);
> mutex_init(&ptp->pincfg_mux);
> + mutex_init(&ptp->n_vclocks_mux);
> init_waitqueue_head(&ptp->tsev_wq);
>
> if (ptp->info->do_aux_work) {
> @@ -221,6 +233,14 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
> ptp->pps_source->lookup_cookie = ptp;
> }
>
> + /* PTP virtual clock is being registered under physical clock */
> + if (parent->class && parent->class->name &&
> + strcmp(parent->class->name, "ptp") == 0)
> + ptp->is_virtual_clock = true;
> +
> + if (!ptp->is_virtual_clock)
> + ptp->max_vclocks = PTP_DEFAULT_MAX_VCLOCKS;
> +
> err = ptp_populate_pin_groups(ptp);
> if (err)
> goto no_pin_groups;
> @@ -270,6 +290,7 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
> kworker_err:
> mutex_destroy(&ptp->tsevq_mux);
> mutex_destroy(&ptp->pincfg_mux);
> + mutex_destroy(&ptp->n_vclocks_mux);
> ida_simple_remove(&ptp_clocks_map, index);
> no_slot:
> kfree(ptp);
> @@ -280,6 +301,11 @@ EXPORT_SYMBOL(ptp_clock_register);
>
> int ptp_clock_unregister(struct ptp_clock *ptp)
> {
> + if (ptp_vclock_in_use(ptp)) {
> + pr_err("ptp: virtual clock in use\n");
> + return -EBUSY;
> + }
> +

None of the drivers (that I looked) expect ptp_clock_unregister() to
return an error.

So, what should we do?
1. Fix all the drivers to return an error on module unloading (that's
usually the path ptp_clock_unregister() is called)?
2. Remove all the PTP virtual clocks when the physical clock is
unregistered?

(And as always, I could be missing something obvious here)

Sorry for being (extremely) late about this.


Cheers,
--
Vinicius

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