On Tue, Jun 15, 2021 at 05:45:08PM +0800, Yangbo Lu wrote:
> diff --git a/drivers/ptp/Makefile b/drivers/ptp/Makefile
> index 8673d1743faa..3c6a905760e2 100644
> --- a/drivers/ptp/Makefile
> +++ b/drivers/ptp/Makefile
> @@ -3,7 +3,7 @@
> # Makefile for PTP 1588 clock support.
> #
>
> -ptp-y := ptp_clock.o ptp_chardev.o ptp_sysfs.o
> +ptp-y := ptp_clock.o ptp_vclock.o ptp_chardev.o ptp_sysfs.o
Nit: Please place ptp_vclock.o at the end of the list.
> ptp_kvm-$(CONFIG_X86) := ptp_kvm_x86.o ptp_kvm_common.o
> ptp_kvm-$(CONFIG_HAVE_ARM_SMCCC) := ptp_kvm_arm.o ptp_kvm_common.o
> obj-$(CONFIG_PTP_1588_CLOCK) += ptp.o
> diff --git a/drivers/ptp/ptp_private.h b/drivers/ptp/ptp_private.h
> index 6b97155148f1..3f388d63904c 100644
> --- a/drivers/ptp/ptp_private.h
> +++ b/drivers/ptp/ptp_private.h
> @@ -48,6 +48,20 @@ struct ptp_clock {
> struct kthread_delayed_work aux_work;
> };
>
> +#define info_to_vclock(d) container_of((d), struct ptp_vclock, info)
> +#define cc_to_vclock(d) container_of((d), struct ptp_vclock, cc)
> +#define dw_to_vclock(d) container_of((d), struct ptp_vclock, refresh_work)
> +
> +struct ptp_vclock {
> + struct ptp_clock *pclock;
> + struct ptp_clock_info info;
> + struct ptp_clock *clock;
> + struct cyclecounter cc;
> + struct timecounter tc;
> + spinlock_t lock; /* protects tc/cc */
> + struct delayed_work refresh_work;
Can we please have a kthread worker here instead of work?
Experience shows that plain work can be delayed for a long, long time
on busy systems.
> +};
> +
> /*
> * The function queue_cnt() is safe for readers to call without
> * holding q->lock. Readers use this function to verify that the queue
> @@ -89,4 +103,6 @@ extern const struct attribute_group *ptp_groups[];
> int ptp_populate_pin_groups(struct ptp_clock *ptp);
> void ptp_cleanup_pin_groups(struct ptp_clock *ptp);
>
> +struct ptp_vclock *ptp_vclock_register(struct ptp_clock *pclock);
> +void ptp_vclock_unregister(struct ptp_vclock *vclock);
> #endif
> diff --git a/drivers/ptp/ptp_vclock.c b/drivers/ptp/ptp_vclock.c
> new file mode 100644
> index 000000000000..b8f500677314
> --- /dev/null
> +++ b/drivers/ptp/ptp_vclock.c
> @@ -0,0 +1,154 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * PTP virtual clock driver
> + *
> + * Copyright 2021 NXP
> + */
> +#include <linux/slab.h>
> +#include "ptp_private.h"
> +
> +#define PTP_VCLOCK_CC_MULT (1 << 31)
> +#define PTP_VCLOCK_CC_SHIFT 31
These two are okay, but ...
> +#define PTP_VCLOCK_CC_MULT_NUM (1 << 9)
> +#define PTP_VCLOCK_CC_MULT_DEM 15625ULL
the similarity of naming is confusing for these two. They are only
used in the .adjfine method. How about this?
PTP_VCLOCK_FADJ_NUMERATOR, or even PTP_VCLOCK_FADJ_SHIFT (see below)
PTP_VCLOCK_FADJ_DENOMINATOR
> +#define PTP_VCLOCK_CC_REFRESH_INTERVAL (HZ * 2)
Consider dropping CC from the name.
PTP_VCLOCK_REFRESH_INTERVAL sounds good to me.
> +static int ptp_vclock_adjfine(struct ptp_clock_info *ptp, long scaled_ppm)
> +{
> + struct ptp_vclock *vclock = info_to_vclock(ptp);
> + unsigned long flags;
> + s64 adj;
> +
> + adj = (s64)scaled_ppm * PTP_VCLOCK_CC_MULT_NUM;
Rather than
scaled_ppm * (1 << 9)
I suggest
scaled_ppm << 9
instead. I suppose a good compiler would replace the multiplication
with a bit shift, but it never hurts to spell it out.
> + adj = div_s64(adj, PTP_VCLOCK_CC_MULT_DEM);
> +
> + spin_lock_irqsave(&vclock->lock, flags);
> + timecounter_read(&vclock->tc);
> + vclock->cc.mult = PTP_VCLOCK_CC_MULT + adj;
> + spin_unlock_irqrestore(&vclock->lock, flags);
> +
> + return 0;
> +}
Thanks,
Richard
