Re: [PATCH v16 00/14] Introduce the Counter character device interface

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 30 Aug 2021 18:17:06 +0100
Jonathan Cameron <jic23@kernel.org> wrote:

> On Fri, 27 Aug 2021 12:47:44 +0900
> William Breathitt Gray <vilhelm.gray@gmail.com> wrote:
> 
> > Changes in v16:
> >  - Define magic numbers for stm32-lptimer-cnt clock polarities
> >  - Define magic numbers for stm32-timer-cnt encoder modes
> >  - Bump KernelVersion to 5.16 in sysfs-bus-counter ABI documentation
> >  - Fix typos in driver API generic-counter.rst documentation file
> > 
> > For convenience, this patchset is also available on my personal git
> > repo: https://gitlab.com/vilhelmgray/iio/-/tree/counter_chrdev_v16
> > 
> > The patches preceding "counter: Internalize sysfs interface code" are
> > primarily cleanup and fixes that can be picked up and applied now to the
> > IIO tree if so desired. The "counter: Internalize sysfs interface code"
> > patch as well may be considered for pickup because it is relatively safe
> > and makes no changes to the userspace interface.
> > 
> > To summarize the main points of this patchset: there are no changes to
> > the existing Counter sysfs userspace interface; a Counter character
> > device interface is introduced that allows Counter events and associated
> > data to be read() by userspace; the events_configure() and
> > watch_validate() driver callbacks are introduced to support Counter
> > events; and IRQ support is added to the 104-QUAD-8 driver, serving as an
> > example of how to support the new Counter events functionality.  
> 
> Hi William,
> 
> I'll aim to pick up the first part in a week (too tired today after a lot
> of reviewing to even manage the basic sanity check on the changes).
> 
> For the rest...
> 
> What I'd really like to know is if anyone other than William and I is planning
> to review them in depth? (particularly 7 and 8 which are the new interface
> patch and docs)
> 
> So if anyone reading this is in that category please let me know.  We can wait,
> but conversely if no one is going to get time / inclination to do it then I
> don't want to hold these up any longer and maximum time in linux-next may
> be more useful than sitting unloved on the mailing list.

Ah well, looks like it's just the two of us for the chrdev core patches :)

Anyhow, I found time for a more thorough review.  I'm not 100% convinced on
the model for the chrdev but you know a lot more about this sort of hardware than
I do and it definitely seems reasonable - if anything it might be more flexible
than it needs to be.

I've highlighted a few small things in the patches.  With those fixed I'm happy
to apply the remainder of this series unless someone shouts in the meantime.

There has been plenty of time for review, so fingers crossed that anyone
who hasn't commented, but cares, is happy with how you have done it.

So, lucky v17!  Persistence pays off in the end.

Thanks,

Jonathan

> 
> Jonathan
> 
> > 
> > William Breathitt Gray (14):
> >   counter: stm32-lptimer-cnt: Provide defines for clock polarities
> >   counter: stm32-timer-cnt: Provide defines for slave mode selection
> >   counter: Internalize sysfs interface code
> >   counter: Update counter.h comments to reflect sysfs internalization
> >   docs: counter: Update to reflect sysfs internalization
> >   counter: Move counter enums to uapi header
> >   counter: Add character device interface
> >   docs: counter: Document character device interface
> >   tools/counter: Create Counter tools
> >   counter: Implement signalZ_action_component_id sysfs attribute
> >   counter: Implement *_component_id sysfs attributes
> >   counter: Implement events_queue_size sysfs attribute
> >   counter: 104-quad-8: Replace mutex with spinlock
> >   counter: 104-quad-8: Add IRQ support for the ACCES 104-QUAD-8
> > 
> >  Documentation/ABI/testing/sysfs-bus-counter   |   38 +-
> >  Documentation/driver-api/generic-counter.rst  |  358 +++-
> >  .../userspace-api/ioctl/ioctl-number.rst      |    1 +
> >  MAINTAINERS                                   |    3 +-
> >  drivers/counter/104-quad-8.c                  |  699 ++++----
> >  drivers/counter/Kconfig                       |    6 +-
> >  drivers/counter/Makefile                      |    1 +
> >  drivers/counter/counter-chrdev.c              |  553 ++++++
> >  drivers/counter/counter-chrdev.h              |   14 +
> >  drivers/counter/counter-core.c                |  191 +++
> >  drivers/counter/counter-sysfs.c               |  960 +++++++++++
> >  drivers/counter/counter-sysfs.h               |   13 +
> >  drivers/counter/counter.c                     | 1496 -----------------
> >  drivers/counter/ftm-quaddec.c                 |   60 +-
> >  drivers/counter/intel-qep.c                   |  144 +-
> >  drivers/counter/interrupt-cnt.c               |   62 +-
> >  drivers/counter/microchip-tcb-capture.c       |   91 +-
> >  drivers/counter/stm32-lptimer-cnt.c           |  212 ++-
> >  drivers/counter/stm32-timer-cnt.c             |  195 +--
> >  drivers/counter/ti-eqep.c                     |  180 +-
> >  include/linux/counter.h                       |  715 ++++----
> >  include/linux/counter_enum.h                  |   45 -
> >  include/linux/mfd/stm32-lptimer.h             |    5 +
> >  include/linux/mfd/stm32-timers.h              |    4 +
> >  include/uapi/linux/counter.h                  |  154 ++
> >  tools/Makefile                                |   13 +-
> >  tools/counter/Build                           |    1 +
> >  tools/counter/Makefile                        |   53 +
> >  tools/counter/counter_example.c               |   93 +
> >  29 files changed, 3569 insertions(+), 2791 deletions(-)
> >  create mode 100644 drivers/counter/counter-chrdev.c
> >  create mode 100644 drivers/counter/counter-chrdev.h
> >  create mode 100644 drivers/counter/counter-core.c
> >  create mode 100644 drivers/counter/counter-sysfs.c
> >  create mode 100644 drivers/counter/counter-sysfs.h
> >  delete mode 100644 drivers/counter/counter.c
> >  delete mode 100644 include/linux/counter_enum.h
> >  create mode 100644 include/uapi/linux/counter.h
> >  create mode 100644 tools/counter/Build
> >  create mode 100644 tools/counter/Makefile
> >  create mode 100644 tools/counter/counter_example.c
> > 
> > 
> > base-commit: 5ffeb17c0d3dd44704b4aee83e297ec07666e4d6  
>