linux-toradex.git/include/linux/ptp_clock_kernel.h, branch v4.19-rc5

ptp: introduce ptp auxiliary worker

2017-08-01T22:22:55+00:00

Many PTP drivers required to perform some asynchronous or periodic work,
like periodically handling PHC counter overflow or handle delayed timestamp
for RX/TX network packets. In most of the cases, such work is implemented
using workqueues. Unfortunately, Kernel workqueues might introduce
significant delay in work scheduling under high system load and on -RT,
which could cause misbehavior of PTP drivers due to internal counter
overflow, for example, and there is no way to tune its execution policy and
priority manuallly.

Hence, The kthread_worker can be used insted of workqueues, as it create
separte named kthread for each worker and its its execution policy and
priority can be configured using chrt tool.

This prblem was reported for two drivers TI CPSW CPTS and dp83640, so
instead of modifying each of these driver it was proposed to add PTP
auxiliary worker to the PHC subsystem.

The patch adds PTP auxiliary worker in PHC subsystem using kthread_worker
and kthread_delayed_work and introduces two new PHC subsystem APIs:

- long (*do_aux_work)(struct ptp_clock_info *ptp) callback in
ptp_clock_info structure, which driver should assign if it require to
perform asynchronous or periodic work. Driver should return the delay of
the PTP next auxiliary work scheduling time (>=0) or negative value in case
further scheduling is not required.

- int ptp_schedule_worker(struct ptp_clock *ptp, unsigned long delay) which
allows schedule PTP auxiliary work.

The name of kthread_worker thread corresponds PTP PHC device name "ptp%d".

Signed-off-by: Grygorii Strashko 
Signed-off-by: David S. Miller

Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-12-13T03:56:15+00:00

Pull timer updates from Thomas Gleixner:
 "The time/timekeeping/timer folks deliver with this update:

   - Fix a reintroduced signed/unsigned issue and cleanup the whole
     signed/unsigned mess in the timekeeping core so this wont happen
     accidentaly again.

   - Add a new trace clock based on boot time

   - Prevent injection of random sleep times when PM tracing abuses the
     RTC for storage

   - Make posix timers configurable for real tiny systems

   - Add tracepoints for the alarm timer subsystem so timer based
     suspend wakeups can be instrumented

   - The usual pile of fixes and updates to core and drivers"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  timekeeping: Use mul_u64_u32_shr() instead of open coding it
  timekeeping: Get rid of pointless typecasts
  timekeeping: Make the conversion call chain consistently unsigned
  timekeeping_Force_unsigned_clocksource_to_nanoseconds_conversion
  alarmtimer: Add tracepoints for alarm timers
  trace: Update documentation for mono, mono_raw and boot clock
  trace: Add an option for boot clock as trace clock
  timekeeping: Add a fast and NMI safe boot clock
  timekeeping/clocksource_cyc2ns: Document intended range limitation
  timekeeping: Ignore the bogus sleep time if pm_trace is enabled
  selftests/timers: Fix spelling mistake "Asyncrhonous" -> "Asynchronous"
  clocksource/drivers/bcm2835_timer: Unmap region obtained by of_iomap
  clocksource/drivers/arm_arch_timer: Map frame with of_io_request_and_map()
  arm64: dts: rockchip: Arch counter doesn't tick in system suspend
  clocksource/drivers/arm_arch_timer: Don't assume clock runs in suspend
  posix-timers: Make them configurable
  posix_cpu_timers: Move the add_device_randomness() call to a proper place
  timer: Move sys_alarm from timer.c to itimer.c
  ptp_clock: Allow for it to be optional
  Kconfig: Regenerate *.c_shipped files after previous changes
  ...

ptp_clock: Allow for it to be optional

2016-11-16T08:26:34+00:00

In order to break the hard dependency between the PTP clock subsystem and
ethernet drivers capable of being clock providers, this patch provides
simple PTP stub functions to allow linkage of those drivers into the
kernel even when the PTP subsystem is configured out. Drivers must be
ready to accept NULL from ptp_clock_register() in that case.

And to make it possible for PTP to be configured out, the select statement
in those driver's Kconfig menu entries is converted to the new "imply"
statement. This way the PTP subsystem may have Kconfig dependencies of
its own, such as POSIX_TIMERS, without having to make those ethernet
drivers unavailable if POSIX timers are cconfigured out. And when support
for POSIX timers is selected again then the default config option for PTP
clock support will automatically be adjusted accordingly.

The pch_gbe driver is a bit special as it relies on extra code in
drivers/ptp/ptp_pch.c. Therefore we let the make process descend into
drivers/ptp/ even if PTP_1588_CLOCK is unselected.

Signed-off-by: Nicolas Pitre 
Acked-by: Richard Cochran 
Acked-by: Edward Cree 
Acked-by: Thomas Gleixner 
Acked-by: John Stultz 
Reviewed-by: Josh Triplett 
Cc: Paul Bolle 
Cc: linux-kbuild@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: Michal Marek 
Link: http://lkml.kernel.org/r/1478841010-28605-4-git-send-email-nicolas.pitre@linaro.org
Signed-off-by: Thomas Gleixner

ptp: Introduce a high resolution frequency adjustment method.

2016-11-10T02:19:53+00:00

The internal PTP Hardware Clock (PHC) interface limits the resolution for
frequency adjustments to one part per billion.  However, some hardware
devices allow finer adjustment, and making use of the increased resolution
improves synchronization measurably on such devices.

This patch adds an alternative method that allows finer frequency tuning
by passing the scaled ppm value to PHC drivers.  This value comes from
user space, and it has a resolution of about 0.015 ppb.  We also deprecate
the older method, anticipating its removal once existing drivers have been
converted over.

Signed-off-by: Richard Cochran 
Suggested-by: Ulrik De Bie 
Signed-off-by: David S. Miller

ptp_clock: future-proofing drivers against PTP subsystem becoming optional

2016-09-22T06:18:33+00:00

Drivers must be ready to accept NULL from ptp_clock_register() if the
PTP clock subsystem is configured out.

This patch documents that and ensures that all drivers cope well
with a NULL return.

Signed-off-by: Nicolas Pitre 
Reviewed-by: Eugenia Emantayev 
Acked-by: Richard Cochran 
Acked-by: Edward Cree 
Signed-off-by: David S. Miller

ptp: Add PTP_SYS_OFFSET_PRECISE for driver crosstimestamping

2016-03-03T22:23:43+00:00

Currently, network /system cross-timestamping is performed in the
PTP_SYS_OFFSET ioctl. The PTP clock driver reads gettimeofday() and
the gettime64() callback provided by the driver. The cross-timestamp
is best effort where the latency between the capture of system time
(getnstimeofday()) and the device time (driver callback) may be
significant.

The getcrosststamp() callback and corresponding PTP_SYS_OFFSET_PRECISE
ioctl allows the driver to perform this device/system correlation when
for example cross timestamp hardware is available. Modern Intel
systems can do this for onboard Ethernet controllers using the ART
counter. There is virtually zero latency between captures of the ART
and network device clock.

The capabilities ioctl (PTP_CLOCK_GETCAPS), is augmented allowing
applications to query whether or not drivers implement the
getcrosststamp callback, providing more precise cross timestamping.

Cc: Prarit Bhargava 
Cc: Richard Cochran 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Andy Lutomirski 
Cc: kevin.b.stanton@intel.com
Cc: kevin.j.clarke@intel.com
Cc: hpa@zytor.com
Cc: jeffrey.t.kirsher@intel.com
Cc: netdev@vger.kernel.org
Acked-by: Richard Cochran 
Signed-off-by: Christopher S. Hall 
[jstultz: Commit subject tweaks]
Signed-off-by: John Stultz

ptp: remove 32 bit get/set methods.

2015-03-31T16:01:19+00:00

All of the PHC drivers have been converted to the new methods.  This patch
converts the three remaining callers within the core code and removes the
older methods for good.  As a result, the core PHC code is ready for the
year 2038.  However, some of the PHC drivers are not quite ready yet.

Signed-off-by: Richard Cochran 
Signed-off-by: David S. Miller

ptp: introduce get/set time methods with explicit 64 bit seconds.

2015-03-31T16:01:16+00:00

Converting the PHC drivers over to the new methods is one step along the
way to making them ready for 2038.  Once all the drivers are up to date,
then the old methods will be removed.

Signed-off-by: Richard Cochran 
Signed-off-by: David S. Miller

ptp: introduce programmable pins.

2014-03-21T18:21:13+00:00

This patch adds a pair of new ioctls to the PTP Hardware Clock device
interface. Using the ioctls, user space programs can query each pin to
find out its current function and also reprogram a different function
if desired.

Signed-off-by: Richard Cochran 
Signed-off-by: David S. Miller

ptp: update adjfreq callback description

2012-11-03T19:27:07+00:00

This patch updates the adjfreq callback description to include a note that the
delta in ppb is always relative to the base frequency, and not to the current
frequency of the hardware clock.

Signed-off-by: Jacob Keller 
CC: stable@vger.kernel.org [v3.5+]
CC: Richard Cochran 
CC: John Stultz 
Signed-off-by: Jeff Kirsher 
Signed-off-by: David S. Miller