[v3,net-next,06/10] net: ptp: create a mock-up PTP Hardware Clock driver

Commit Message

Vladimir Oltean Aug. 1, 2023, 6:24 p.m. UTC

There are several cases where virtual net devices may benefit from
having a PTP clock, and these have to do with testing. I can see at
least netdevsim and veth as potential users of a common mock-up PTP
hardware clock driver.

The proposed idea is to create an object which emulates PTP clock
operations on top of the unadjustable CLOCK_MONOTONIC_RAW plus a
software-controlled time domain via a timecounter/cyclecounter and then
link that PHC to the netdevsim device.

The driver is fully functional for its intended purpose, and it
successfully passes the PTP selftests.

$ cd tools/testing/selftests/ptp/
$ ./phc.sh /dev/ptp2
TEST: settime                          [ OK ]
TEST: adjtime                          [ OK ]
TEST: adjfreq                          [ OK ]

Signed-off-by: Vladimir Oltean <[e-mail]>
---
v2->v3:
- split off ptp_mock into separate patch
- fix ptp_mock compilation as a module
- turn phc->lock into a global spinlock
- drop bogus support for ptp_clock_register() ever returning NULL
- add MAINTAINERS entry
v1->v2: patch is new

 MAINTAINERS              |   7 ++
 drivers/ptp/Kconfig      |  11 +++
 drivers/ptp/Makefile     |   1 +
 drivers/ptp/ptp_mock.c   | 175 +++++++++++++++++++++++++++++++++++++++
 include/linux/ptp_mock.h |  38 +++++++++
 5 files changed, 232 insertions(+)
 create mode 100644 drivers/ptp/ptp_mock.c
 create mode 100644 include/linux/ptp_mock.h

Comments

Kurt Kanzenbach Aug. 2, 2023, 12:18 p.m. UTC | #1

Hi Vladimir,

this looks good. One question below.

On Tue Aug 01 2023, Vladimir Oltean wrote:
> There are several cases where virtual net devices may benefit from
> having a PTP clock, and these have to do with testing. I can see at
> least netdevsim and veth as potential users of a common mock-up PTP
> hardware clock driver.
>
> The proposed idea is to create an object which emulates PTP clock
> operations on top of the unadjustable CLOCK_MONOTONIC_RAW plus a
> software-controlled time domain via a timecounter/cyclecounter and then
> link that PHC to the netdevsim device.
>
> The driver is fully functional for its intended purpose, and it
> successfully passes the PTP selftests.
>
> $ cd tools/testing/selftests/ptp/
> $ ./phc.sh /dev/ptp2
> TEST: settime                          [ OK ]
> TEST: adjtime                          [ OK ]
> TEST: adjfreq                          [ OK ]
>
> Signed-off-by: Vladimir Oltean <[e-mail]>
> ---
> v2->v3:
> - split off ptp_mock into separate patch
> - fix ptp_mock compilation as a module
> - turn phc->lock into a global spinlock
> - drop bogus support for ptp_clock_register() ever returning NULL
> - add MAINTAINERS entry
> v1->v2: patch is new
>
>  MAINTAINERS              |   7 ++
>  drivers/ptp/Kconfig      |  11 +++
>  drivers/ptp/Makefile     |   1 +
>  drivers/ptp/ptp_mock.c   | 175 +++++++++++++++++++++++++++++++++++++++
>  include/linux/ptp_mock.h |  38 +++++++++
>  5 files changed, 232 insertions(+)
>  create mode 100644 drivers/ptp/ptp_mock.c
>  create mode 100644 include/linux/ptp_mock.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c4f95a9d03b9..164b7930f5d0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -17175,6 +17175,13 @@ F:	drivers/ptp/*
>  F:	include/linux/ptp_cl*
>  K:	(?:\b|_)ptp(?:\b|_)
>  
> +PTP MOCKUP CLOCK SUPPORT
> +M:	Vladimir Oltean <[e-mail]>
> +L:	[e-mail]
> +S:	Maintained
> +F:	drivers/ptp/ptp_mock.c
> +F:	include/linux/ptp_mock.h
> +
>  PTP VIRTUAL CLOCK SUPPORT
>  M:	Yangbo Lu <[e-mail]>
>  L:	[e-mail]
> diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig
> index 32dff1b4f891..ed9d97a032f1 100644
> --- a/drivers/ptp/Kconfig
> +++ b/drivers/ptp/Kconfig
> @@ -155,6 +155,17 @@ config PTP_1588_CLOCK_IDTCM
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called ptp_clockmatrix.
>  
> +config PTP_1588_CLOCK_MOCK
> +	tristate "Mock-up PTP clock"
> +	depends on PTP_1588_CLOCK
> +	help
> +	  This driver offers a set of PTP clock manipulation operations over
> +	  the system monotonic time. It can be used by virtual network device
> +	  drivers to emulate PTP capabilities.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called ptp_mock.
> +
>  config PTP_1588_CLOCK_VMW
>  	tristate "VMware virtual PTP clock"
>  	depends on ACPI && HYPERVISOR_GUEST && X86
> diff --git a/drivers/ptp/Makefile b/drivers/ptp/Makefile
> index 553f18bf3c83..dea0cebd2303 100644
> --- a/drivers/ptp/Makefile
> +++ b/drivers/ptp/Makefile
> @@ -16,6 +16,7 @@ ptp-qoriq-y				+= ptp_qoriq.o
>  ptp-qoriq-$(CONFIG_DEBUG_FS)		+= ptp_qoriq_debugfs.o
>  obj-$(CONFIG_PTP_1588_CLOCK_IDTCM)	+= ptp_clockmatrix.o
>  obj-$(CONFIG_PTP_1588_CLOCK_IDT82P33)	+= ptp_idt82p33.o
> +obj-$(CONFIG_PTP_1588_CLOCK_MOCK)	+= ptp_mock.o
>  obj-$(CONFIG_PTP_1588_CLOCK_VMW)	+= ptp_vmw.o
>  obj-$(CONFIG_PTP_1588_CLOCK_OCP)	+= ptp_ocp.o
>  obj-$(CONFIG_PTP_DFL_TOD)		+= ptp_dfl_tod.o
> diff --git a/drivers/ptp/ptp_mock.c b/drivers/ptp/ptp_mock.c
> new file mode 100644
> index 000000000000..1525aafca752
> --- /dev/null
> +++ b/drivers/ptp/ptp_mock.c
> @@ -0,0 +1,175 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright 2023 NXP
> + *
> + * Mock-up PTP Hardware Clock driver for virtual network devices
> + *
> + * Create a PTP clock which offers PTP time manipulation operations
> + * using a timecounter/cyclecounter on top of CLOCK_MONOTONIC_RAW.
> + */
> +
> +#include <linux/ptp_clock_kernel.h>
> +#include <linux/ptp_mock.h>
> +#include <linux/timecounter.h>
> +
> +/* Clamp scaled_ppm between -2,097,152,000 and 2,097,152,000,
> + * and thus "adj" between -68,719,476 and 68,719,476
> + */
> +#define MOCK_PHC_MAX_ADJ_PPB		32000000
> +/* Timestamps from ktime_get_raw() have 1 ns resolution, so the scale factor
> + * (MULT >> SHIFT) needs to be 1. Pick SHIFT as 31 bits, which translates
> + * MULT(freq 0) into 0x80000000.
> + */
> +#define MOCK_PHC_CC_SHIFT		31
> +#define MOCK_PHC_CC_MULT		(1 << MOCK_PHC_CC_SHIFT)
> +#define MOCK_PHC_FADJ_SHIFT		9
> +#define MOCK_PHC_FADJ_DENOMINATOR	15625ULL
> +
> +/* The largest cycle_delta that timecounter_read_delta() can handle without a
> + * 64-bit overflow during the multiplication with cc->mult, given the max "adj"
> + * we permit, is ~8.3 seconds. Make sure readouts are more frequent than that.
> + */
> +#define MOCK_PHC_REFRESH_INTERVAL	(HZ * 5)
> +
> +#define info_to_phc(d) container_of((d), struct mock_phc, info)
> +
> +static DEFINE_SPINLOCK(mock_phc_lock);
> +
> +struct mock_phc {
> +	struct ptp_clock_info info;
> +	struct ptp_clock *clock;
> +	struct timecounter tc;
> +	struct cyclecounter cc;
> +};
> +
> +static u64 mock_phc_cc_read(const struct cyclecounter *cc)
> +{
> +	return ktime_to_ns(ktime_get_raw());

Maybe return ktime_get_raw_ns()?

> +}
> +
> +static int mock_phc_adjfine(struct ptp_clock_info *info, long scaled_ppm)
> +{
> +	struct mock_phc *phc = info_to_phc(info);
> +	s64 adj;
> +
> +	adj = (s64)scaled_ppm << MOCK_PHC_FADJ_SHIFT;
> +	adj = div_s64(adj, MOCK_PHC_FADJ_DENOMINATOR);
> +
> +	spin_lock_bh(&mock_phc_lock);

Why spin_lock_bh()? What's executed in bh context here? The PTP aux
worker runs in thread context.

Thanks,
Kurt

Vladimir Oltean Aug. 2, 2023, 12:43 p.m. UTC | #2

Hi Kurt,

On Wed, Aug 02, 2023 at 02:18:10PM +0200, Kurt Kanzenbach wrote:
> > +static u64 mock_phc_cc_read(const struct cyclecounter *cc)
> > +{
> > +	return ktime_to_ns(ktime_get_raw());
> 
> Maybe return ktime_get_raw_ns()?

Maybe.. Didn't notice that there's a helper which does exactly this.

> > +}
> > +
> > +static int mock_phc_adjfine(struct ptp_clock_info *info, long scaled_ppm)
> > +{
> > +	struct mock_phc *phc = info_to_phc(info);
> > +	s64 adj;
> > +
> > +	adj = (s64)scaled_ppm << MOCK_PHC_FADJ_SHIFT;
> > +	adj = div_s64(adj, MOCK_PHC_FADJ_DENOMINATOR);
> > +
> > +	spin_lock_bh(&mock_phc_lock);
> 
> Why spin_lock_bh()? What's executed in bh context here? The PTP aux
> worker runs in thread context.

Correct, thanks for spotting. This is a left-over from some other
(unsubmitted) functionality I was working on. In the submitted variant,
nothing runs in softirq context, and thus, bottom halves don't need to
be disabled.

If there's nothing functionally broken, I think I'd prefer to address
both comments with follow-up patches rather than respinning this 10-patch
series. The build testing for this series still has not finished yet,
since yesterday.

Thanks for reviewing.

Vinicius Costa Gomes Aug. 2, 2023, 9:58 p.m. UTC | #3

Vladimir Oltean <[e-mail]> writes:

> There are several cases where virtual net devices may benefit from
> having a PTP clock, and these have to do with testing. I can see at
> least netdevsim and veth as potential users of a common mock-up PTP
> hardware clock driver.
>
> The proposed idea is to create an object which emulates PTP clock
> operations on top of the unadjustable CLOCK_MONOTONIC_RAW plus a
> software-controlled time domain via a timecounter/cyclecounter and then
> link that PHC to the netdevsim device.
>
> The driver is fully functional for its intended purpose, and it
> successfully passes the PTP selftests.
>
> $ cd tools/testing/selftests/ptp/
> $ ./phc.sh /dev/ptp2
> TEST: settime                          [ OK ]
> TEST: adjtime                          [ OK ]
> TEST: adjfreq                          [ OK ]
>
> Signed-off-by: Vladimir Oltean <[e-mail]>
> ---
> v2->v3:
> - split off ptp_mock into separate patch
> - fix ptp_mock compilation as a module
> - turn phc->lock into a global spinlock
> - drop bogus support for ptp_clock_register() ever returning NULL
> - add MAINTAINERS entry
> v1->v2: patch is new
>
>  MAINTAINERS              |   7 ++
>  drivers/ptp/Kconfig      |  11 +++
>  drivers/ptp/Makefile     |   1 +
>  drivers/ptp/ptp_mock.c   | 175 +++++++++++++++++++++++++++++++++++++++
>  include/linux/ptp_mock.h |  38 +++++++++
>  5 files changed, 232 insertions(+)
>  create mode 100644 drivers/ptp/ptp_mock.c
>  create mode 100644 include/linux/ptp_mock.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c4f95a9d03b9..164b7930f5d0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -17175,6 +17175,13 @@ F:	drivers/ptp/*
>  F:	include/linux/ptp_cl*
>  K:	(?:\b|_)ptp(?:\b|_)
>  
> +PTP MOCKUP CLOCK SUPPORT
> +M:	Vladimir Oltean <[e-mail]>
> +L:	[e-mail]
> +S:	Maintained
> +F:	drivers/ptp/ptp_mock.c
> +F:	include/linux/ptp_mock.h
> +
>  PTP VIRTUAL CLOCK SUPPORT
>  M:	Yangbo Lu <[e-mail]>
>  L:	[e-mail]
> diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig
> index 32dff1b4f891..ed9d97a032f1 100644
> --- a/drivers/ptp/Kconfig
> +++ b/drivers/ptp/Kconfig
> @@ -155,6 +155,17 @@ config PTP_1588_CLOCK_IDTCM
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called ptp_clockmatrix.
>  
> +config PTP_1588_CLOCK_MOCK
> +	tristate "Mock-up PTP clock"
> +	depends on PTP_1588_CLOCK
> +	help
> +	  This driver offers a set of PTP clock manipulation operations over
> +	  the system monotonic time. It can be used by virtual network device
> +	  drivers to emulate PTP capabilities.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called ptp_mock.
> +
>  config PTP_1588_CLOCK_VMW
>  	tristate "VMware virtual PTP clock"
>  	depends on ACPI && HYPERVISOR_GUEST && X86
> diff --git a/drivers/ptp/Makefile b/drivers/ptp/Makefile
> index 553f18bf3c83..dea0cebd2303 100644
> --- a/drivers/ptp/Makefile
> +++ b/drivers/ptp/Makefile
> @@ -16,6 +16,7 @@ ptp-qoriq-y				+= ptp_qoriq.o
>  ptp-qoriq-$(CONFIG_DEBUG_FS)		+= ptp_qoriq_debugfs.o
>  obj-$(CONFIG_PTP_1588_CLOCK_IDTCM)	+= ptp_clockmatrix.o
>  obj-$(CONFIG_PTP_1588_CLOCK_IDT82P33)	+= ptp_idt82p33.o
> +obj-$(CONFIG_PTP_1588_CLOCK_MOCK)	+= ptp_mock.o
>  obj-$(CONFIG_PTP_1588_CLOCK_VMW)	+= ptp_vmw.o
>  obj-$(CONFIG_PTP_1588_CLOCK_OCP)	+= ptp_ocp.o
>  obj-$(CONFIG_PTP_DFL_TOD)		+= ptp_dfl_tod.o
> diff --git a/drivers/ptp/ptp_mock.c b/drivers/ptp/ptp_mock.c
> new file mode 100644
> index 000000000000..1525aafca752
> --- /dev/null
> +++ b/drivers/ptp/ptp_mock.c
> @@ -0,0 +1,175 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright 2023 NXP
> + *
> + * Mock-up PTP Hardware Clock driver for virtual network devices
> + *
> + * Create a PTP clock which offers PTP time manipulation operations
> + * using a timecounter/cyclecounter on top of CLOCK_MONOTONIC_RAW.
> + */
> +
> +#include <linux/ptp_clock_kernel.h>
> +#include <linux/ptp_mock.h>
> +#include <linux/timecounter.h>
> +
> +/* Clamp scaled_ppm between -2,097,152,000 and 2,097,152,000,
> + * and thus "adj" between -68,719,476 and 68,719,476
> + */
> +#define MOCK_PHC_MAX_ADJ_PPB		32000000
> +/* Timestamps from ktime_get_raw() have 1 ns resolution, so the scale factor
> + * (MULT >> SHIFT) needs to be 1. Pick SHIFT as 31 bits, which translates
> + * MULT(freq 0) into 0x80000000.
> + */
> +#define MOCK_PHC_CC_SHIFT		31
> +#define MOCK_PHC_CC_MULT		(1 << MOCK_PHC_CC_SHIFT)
> +#define MOCK_PHC_FADJ_SHIFT		9
> +#define MOCK_PHC_FADJ_DENOMINATOR	15625ULL
> +
> +/* The largest cycle_delta that timecounter_read_delta() can handle without a
> + * 64-bit overflow during the multiplication with cc->mult, given the max "adj"
> + * we permit, is ~8.3 seconds. Make sure readouts are more frequent than that.
> + */
> +#define MOCK_PHC_REFRESH_INTERVAL	(HZ * 5)
> +
> +#define info_to_phc(d) container_of((d), struct mock_phc, info)
> +
> +static DEFINE_SPINLOCK(mock_phc_lock);
> +

Not a big deal, but as it is possible to have multiple netdevsim
instances (is it?), I think it's better to move the lock inside struct
mock_phc.

> +struct mock_phc {
> +	struct ptp_clock_info info;
> +	struct ptp_clock *clock;
> +	struct timecounter tc;
> +	struct cyclecounter cc;
> +};
> +
> +static u64 mock_phc_cc_read(const struct cyclecounter *cc)
> +{
> +	return ktime_to_ns(ktime_get_raw());
> +}
> +
> +static int mock_phc_adjfine(struct ptp_clock_info *info, long scaled_ppm)
> +{
> +	struct mock_phc *phc = info_to_phc(info);
> +	s64 adj;
> +
> +	adj = (s64)scaled_ppm << MOCK_PHC_FADJ_SHIFT;
> +	adj = div_s64(adj, MOCK_PHC_FADJ_DENOMINATOR);
> +
> +	spin_lock_bh(&mock_phc_lock);
> +	timecounter_read(&phc->tc);
> +	phc->cc.mult = MOCK_PHC_CC_MULT + adj;
> +	spin_unlock_bh(&mock_phc_lock);
> +
> +	return 0;
> +}
> +
> +static int mock_phc_adjtime(struct ptp_clock_info *info, s64 delta)
> +{
> +	struct mock_phc *phc = info_to_phc(info);
> +
> +	spin_lock_bh(&mock_phc_lock);
> +	timecounter_adjtime(&phc->tc, delta);
> +	spin_unlock_bh(&mock_phc_lock);
> +
> +	return 0;
> +}
> +
> +static int mock_phc_settime64(struct ptp_clock_info *info,
> +			      const struct timespec64 *ts)
> +{
> +	struct mock_phc *phc = info_to_phc(info);
> +	u64 ns = timespec64_to_ns(ts);
> +
> +	spin_lock_bh(&mock_phc_lock);
> +	timecounter_init(&phc->tc, &phc->cc, ns);
> +	spin_unlock_bh(&mock_phc_lock);
> +
> +	return 0;
> +}
> +
> +static int mock_phc_gettime64(struct ptp_clock_info *info, struct timespec64 *ts)
> +{
> +	struct mock_phc *phc = info_to_phc(info);
> +	u64 ns;
> +
> +	spin_lock_bh(&mock_phc_lock);
> +	ns = timecounter_read(&phc->tc);
> +	spin_unlock_bh(&mock_phc_lock);
> +
> +	*ts = ns_to_timespec64(ns);
> +
> +	return 0;
> +}
> +
> +static long mock_phc_refresh(struct ptp_clock_info *info)
> +{
> +	struct timespec64 ts;
> +
> +	mock_phc_gettime64(info, &ts);
> +
> +	return MOCK_PHC_REFRESH_INTERVAL;
> +}
> +
> +int mock_phc_index(struct mock_phc *phc)
> +{
> +	return ptp_clock_index(phc->clock);
> +}
> +EXPORT_SYMBOL_GPL(mock_phc_index);
> +
> +struct mock_phc *mock_phc_create(struct device *dev)
> +{
> +	struct mock_phc *phc;
> +	int err;
> +
> +	phc = kzalloc(sizeof(*phc), GFP_KERNEL);
> +	if (!phc) {
> +		err = -ENOMEM;
> +		goto out;
> +	}
> +
> +	phc->info = (struct ptp_clock_info) {
> +		.owner		= THIS_MODULE,
> +		.name		= "Mock-up PTP clock",
> +		.max_adj	= MOCK_PHC_MAX_ADJ_PPB,
> +		.adjfine	= mock_phc_adjfine,
> +		.adjtime	= mock_phc_adjtime,
> +		.gettime64	= mock_phc_gettime64,
> +		.settime64	= mock_phc_settime64,
> +		.do_aux_work	= mock_phc_refresh,
> +	};
> +
> +	phc->cc = (struct cyclecounter) {
> +		.read	= mock_phc_cc_read,
> +		.mask	= CYCLECOUNTER_MASK(64),
> +		.mult	= MOCK_PHC_CC_MULT,
> +		.shift	= MOCK_PHC_CC_SHIFT,
> +	};
> +
> +	timecounter_init(&phc->tc, &phc->cc, 0);
> +
> +	phc->clock = ptp_clock_register(&phc->info, dev);
> +	if (IS_ERR(phc->clock)) {
> +		err = PTR_ERR(phc->clock);
> +		goto out_free_phc;
> +	}
> +
> +	ptp_schedule_worker(phc->clock, MOCK_PHC_REFRESH_INTERVAL);
> +
> +	return phc;
> +
> +out_free_phc:
> +	kfree(phc);
> +out:
> +	return ERR_PTR(err);
> +}
> +EXPORT_SYMBOL_GPL(mock_phc_create);
> +
> +void mock_phc_destroy(struct mock_phc *phc)
> +{
> +	ptp_clock_unregister(phc->clock);
> +	kfree(phc);
> +}
> +EXPORT_SYMBOL_GPL(mock_phc_destroy);
> +
> +MODULE_DESCRIPTION("Mock-up PTP Hardware Clock driver");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/ptp_mock.h b/include/linux/ptp_mock.h
> new file mode 100644
> index 000000000000..72eb401034d9
> --- /dev/null
> +++ b/include/linux/ptp_mock.h
> @@ -0,0 +1,38 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Mock-up PTP Hardware Clock driver for virtual network devices
> + *
> + * Copyright 2023 NXP
> + */
> +
> +#ifndef _PTP_MOCK_H_
> +#define _PTP_MOCK_H_
> +
> +struct device;
> +struct mock_phc;
> +
> +#if IS_ENABLED(CONFIG_PTP_1588_CLOCK_MOCK)
> +
> +struct mock_phc *mock_phc_create(struct device *dev);
> +void mock_phc_destroy(struct mock_phc *phc);
> +int mock_phc_index(struct mock_phc *phc);
> +
> +#else
> +
> +static inline struct mock_phc *mock_phc_create(struct device *dev)
> +{
> +	return NULL;
> +}
> +
> +static inline void mock_phc_destroy(struct mock_phc *phc)
> +{
> +}
> +
> +static inline int mock_phc_index(struct mock_phc *phc)
> +{
> +	return -1;
> +}
> +
> +#endif
> +
> +#endif /* _PTP_MOCK_H_ */
> -- 
> 2.34.1
>

Vladimir Oltean Aug. 3, 2023, 2:45 p.m. UTC | #4

On Wed, Aug 02, 2023 at 02:58:24PM -0700, Vinicius Costa Gomes wrote:
> > +static DEFINE_SPINLOCK(mock_phc_lock);
> > +
> 
> Not a big deal, but as it is possible to have multiple netdevsim
> instances (is it?), I think it's better to move the lock inside struct
> mock_phc.

Ok. I'll respin with this and Kurt's comments addressed. I'll wait for a
little bit longer, in case there are more change requests.

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index c4f95a9d03b9..164b7930f5d0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17175,6 +17175,13 @@  F:	drivers/ptp/*
 F:	include/linux/ptp_cl*
 K:	(?:\b|_)ptp(?:\b|_)
 
+PTP MOCKUP CLOCK SUPPORT
+M:	Vladimir Oltean <[e-mail]>
+L:	[e-mail]
+S:	Maintained
+F:	drivers/ptp/ptp_mock.c
+F:	include/linux/ptp_mock.h
+
 PTP VIRTUAL CLOCK SUPPORT
 M:	Yangbo Lu <[e-mail]>
 L:	[e-mail]
diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig
index 32dff1b4f891..ed9d97a032f1 100644
--- a/drivers/ptp/Kconfig
+++ b/drivers/ptp/Kconfig
@@ -155,6 +155,17 @@  config PTP_1588_CLOCK_IDTCM
 	  To compile this driver as a module, choose M here: the module
 	  will be called ptp_clockmatrix.
 
+config PTP_1588_CLOCK_MOCK
+	tristate "Mock-up PTP clock"
+	depends on PTP_1588_CLOCK
+	help
+	  This driver offers a set of PTP clock manipulation operations over
+	  the system monotonic time. It can be used by virtual network device
+	  drivers to emulate PTP capabilities.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called ptp_mock.
+
 config PTP_1588_CLOCK_VMW
 	tristate "VMware virtual PTP clock"
 	depends on ACPI && HYPERVISOR_GUEST && X86
diff --git a/drivers/ptp/Makefile b/drivers/ptp/Makefile
index 553f18bf3c83..dea0cebd2303 100644
--- a/drivers/ptp/Makefile
+++ b/drivers/ptp/Makefile
@@ -16,6 +16,7 @@  ptp-qoriq-y				+= ptp_qoriq.o
 ptp-qoriq-$(CONFIG_DEBUG_FS)		+= ptp_qoriq_debugfs.o
 obj-$(CONFIG_PTP_1588_CLOCK_IDTCM)	+= ptp_clockmatrix.o
 obj-$(CONFIG_PTP_1588_CLOCK_IDT82P33)	+= ptp_idt82p33.o
+obj-$(CONFIG_PTP_1588_CLOCK_MOCK)	+= ptp_mock.o
 obj-$(CONFIG_PTP_1588_CLOCK_VMW)	+= ptp_vmw.o
 obj-$(CONFIG_PTP_1588_CLOCK_OCP)	+= ptp_ocp.o
 obj-$(CONFIG_PTP_DFL_TOD)		+= ptp_dfl_tod.o
diff --git a/drivers/ptp/ptp_mock.c b/drivers/ptp/ptp_mock.c
new file mode 100644
index 000000000000..1525aafca752
--- /dev/null
+++ b/drivers/ptp/ptp_mock.c
@@ -0,0 +1,175 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2023 NXP
+ *
+ * Mock-up PTP Hardware Clock driver for virtual network devices
+ *
+ * Create a PTP clock which offers PTP time manipulation operations
+ * using a timecounter/cyclecounter on top of CLOCK_MONOTONIC_RAW.
+ */
+
+#include <linux/ptp_clock_kernel.h>
+#include <linux/ptp_mock.h>
+#include <linux/timecounter.h>
+
+/* Clamp scaled_ppm between -2,097,152,000 and 2,097,152,000,
+ * and thus "adj" between -68,719,476 and 68,719,476
+ */
+#define MOCK_PHC_MAX_ADJ_PPB		32000000
+/* Timestamps from ktime_get_raw() have 1 ns resolution, so the scale factor
+ * (MULT >> SHIFT) needs to be 1. Pick SHIFT as 31 bits, which translates
+ * MULT(freq 0) into 0x80000000.
+ */
+#define MOCK_PHC_CC_SHIFT		31
+#define MOCK_PHC_CC_MULT		(1 << MOCK_PHC_CC_SHIFT)
+#define MOCK_PHC_FADJ_SHIFT		9
+#define MOCK_PHC_FADJ_DENOMINATOR	15625ULL
+
+/* The largest cycle_delta that timecounter_read_delta() can handle without a
+ * 64-bit overflow during the multiplication with cc->mult, given the max "adj"
+ * we permit, is ~8.3 seconds. Make sure readouts are more frequent than that.
+ */
+#define MOCK_PHC_REFRESH_INTERVAL	(HZ * 5)
+
+#define info_to_phc(d) container_of((d), struct mock_phc, info)
+
+static DEFINE_SPINLOCK(mock_phc_lock);
+
+struct mock_phc {
+	struct ptp_clock_info info;
+	struct ptp_clock *clock;
+	struct timecounter tc;
+	struct cyclecounter cc;
+};
+
+static u64 mock_phc_cc_read(const struct cyclecounter *cc)
+{
+	return ktime_to_ns(ktime_get_raw());
+}
+
+static int mock_phc_adjfine(struct ptp_clock_info *info, long scaled_ppm)
+{
+	struct mock_phc *phc = info_to_phc(info);
+	s64 adj;
+
+	adj = (s64)scaled_ppm << MOCK_PHC_FADJ_SHIFT;
+	adj = div_s64(adj, MOCK_PHC_FADJ_DENOMINATOR);
+
+	spin_lock_bh(&mock_phc_lock);
+	timecounter_read(&phc->tc);
+	phc->cc.mult = MOCK_PHC_CC_MULT + adj;
+	spin_unlock_bh(&mock_phc_lock);
+
+	return 0;
+}
+
+static int mock_phc_adjtime(struct ptp_clock_info *info, s64 delta)
+{
+	struct mock_phc *phc = info_to_phc(info);
+
+	spin_lock_bh(&mock_phc_lock);
+	timecounter_adjtime(&phc->tc, delta);
+	spin_unlock_bh(&mock_phc_lock);
+
+	return 0;
+}
+
+static int mock_phc_settime64(struct ptp_clock_info *info,
+			      const struct timespec64 *ts)
+{
+	struct mock_phc *phc = info_to_phc(info);
+	u64 ns = timespec64_to_ns(ts);
+
+	spin_lock_bh(&mock_phc_lock);
+	timecounter_init(&phc->tc, &phc->cc, ns);
+	spin_unlock_bh(&mock_phc_lock);
+
+	return 0;
+}
+
+static int mock_phc_gettime64(struct ptp_clock_info *info, struct timespec64 *ts)
+{
+	struct mock_phc *phc = info_to_phc(info);
+	u64 ns;
+
+	spin_lock_bh(&mock_phc_lock);
+	ns = timecounter_read(&phc->tc);
+	spin_unlock_bh(&mock_phc_lock);
+
+	*ts = ns_to_timespec64(ns);
+
+	return 0;
+}
+
+static long mock_phc_refresh(struct ptp_clock_info *info)
+{
+	struct timespec64 ts;
+
+	mock_phc_gettime64(info, &ts);
+
+	return MOCK_PHC_REFRESH_INTERVAL;
+}
+
+int mock_phc_index(struct mock_phc *phc)
+{
+	return ptp_clock_index(phc->clock);
+}
+EXPORT_SYMBOL_GPL(mock_phc_index);
+
+struct mock_phc *mock_phc_create(struct device *dev)
+{
+	struct mock_phc *phc;
+	int err;
+
+	phc = kzalloc(sizeof(*phc), GFP_KERNEL);
+	if (!phc) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	phc->info = (struct ptp_clock_info) {
+		.owner		= THIS_MODULE,
+		.name		= "Mock-up PTP clock",
+		.max_adj	= MOCK_PHC_MAX_ADJ_PPB,
+		.adjfine	= mock_phc_adjfine,
+		.adjtime	= mock_phc_adjtime,
+		.gettime64	= mock_phc_gettime64,
+		.settime64	= mock_phc_settime64,
+		.do_aux_work	= mock_phc_refresh,
+	};
+
+	phc->cc = (struct cyclecounter) {
+		.read	= mock_phc_cc_read,
+		.mask	= CYCLECOUNTER_MASK(64),
+		.mult	= MOCK_PHC_CC_MULT,
+		.shift	= MOCK_PHC_CC_SHIFT,
+	};
+
+	timecounter_init(&phc->tc, &phc->cc, 0);
+
+	phc->clock = ptp_clock_register(&phc->info, dev);
+	if (IS_ERR(phc->clock)) {
+		err = PTR_ERR(phc->clock);
+		goto out_free_phc;
+	}
+
+	ptp_schedule_worker(phc->clock, MOCK_PHC_REFRESH_INTERVAL);
+
+	return phc;
+
+out_free_phc:
+	kfree(phc);
+out:
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(mock_phc_create);
+
+void mock_phc_destroy(struct mock_phc *phc)
+{
+	ptp_clock_unregister(phc->clock);
+	kfree(phc);
+}
+EXPORT_SYMBOL_GPL(mock_phc_destroy);
+
+MODULE_DESCRIPTION("Mock-up PTP Hardware Clock driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/ptp_mock.h b/include/linux/ptp_mock.h
new file mode 100644
index 000000000000..72eb401034d9
--- /dev/null
+++ b/include/linux/ptp_mock.h
@@ -0,0 +1,38 @@ 
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Mock-up PTP Hardware Clock driver for virtual network devices
+ *
+ * Copyright 2023 NXP
+ */
+
+#ifndef _PTP_MOCK_H_
+#define _PTP_MOCK_H_
+
+struct device;
+struct mock_phc;
+
+#if IS_ENABLED(CONFIG_PTP_1588_CLOCK_MOCK)
+
+struct mock_phc *mock_phc_create(struct device *dev);
+void mock_phc_destroy(struct mock_phc *phc);
+int mock_phc_index(struct mock_phc *phc);
+
+#else
+
+static inline struct mock_phc *mock_phc_create(struct device *dev)
+{
+	return NULL;
+}
+
+static inline void mock_phc_destroy(struct mock_phc *phc)
+{
+}
+
+static inline int mock_phc_index(struct mock_phc *phc)
+{
+	return -1;
+}
+
+#endif
+
+#endif /* _PTP_MOCK_H_ */