linux-kernel - Re: [PATCH v17 0/9] Introduce the Counter character device interface

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Date:   Thu, 30 Sep 2021 18:21:40 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     William Breathitt Gray <vilhelm.gray@...il.com>
Cc:     linux-stm32@...md-mailman.stormreply.com, kernel@...gutronix.de,
        a.fatoum@...gutronix.de, kamel.bouhara@...tlin.com,
        gwendal@...omium.org, alexandre.belloni@...tlin.com,
        david@...hnology.com, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        syednwaris@...il.com, patrick.havelange@...ensium.com,
        fabrice.gasnier@...com, mcoquelin.stm32@...il.com,
        alexandre.torgue@...com, o.rempel@...gutronix.de,
        jarkko.nikula@...ux.intel.com, Peter Rosin <peda@...ntia.se>
Subject: Re: [PATCH v17 0/9] Introduce the Counter character device
 interface

On Wed, 29 Sep 2021 12:15:57 +0900
William Breathitt Gray <vilhelm.gray@...il.com> wrote:

> Changes in v17:
>  - A couple minor improvements to documentation from review suggestions
>  - chrdev_lock redeclared as atomic_t; BITMAP was not necessary because
>    chrdev_lock is a single flag
>  - test_and_set_bit_lock(), clear_bit_unlock(), and clear_bit(),
>    replaced respectively with atomic_add_unless(), atomic_dec(), and
>    atomic_set()
>  - counter_comp_read_is_equal() and counter_comp_read_is_set() macros
>    implemented in order to properly test counter_comp structures' read
>    callback states
>  - counter_sysfs_add() call performed before counter_chrdev_add() call
>    in counter_register() in order to match unwinding sequence
>  - for-loop utilized in counter-example.c in order to simplify code
>  - counter-example.c returns 1 on error instead of -errno; errno may be
>    modified after a subsequent library call so we can't depend on it
> 
> For convenience, this patchset is also available on my personal git
> repo: https://gitlab.com/vilhelmgray/iio/-/tree/counter_chrdev_v17
> 
> 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.

Applied to the togreg branch of iio.git and pushed out as testing for
0-day to see if we missed anything!

I couldn't resist hitting lore.kernel.org for some archaeology on whether
this broke records for a series on the IIO list (i.e. one I'd actually
reviewed :)

It has the dubious honour of being the only series to reach v17 that has
been posted to linux-iio@...r.kernel.org as far as records go back.

Peter Rosin's MUX series got to v15 and that seems to be the previous
record holder joint with an mxs-lradc set from a while back.

Perhaps not a record you wanted to get, but it shows impressive grit
and determination!

Jonathan

> 
> William Breathitt Gray (9):
>   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   |  29 +
>  Documentation/driver-api/generic-counter.rst  | 177 ++++--
>  .../userspace-api/ioctl/ioctl-number.rst      |   1 +
>  MAINTAINERS                                   |   2 +
>  drivers/counter/104-quad-8.c                  | 256 ++++++--
>  drivers/counter/Kconfig                       |   6 +-
>  drivers/counter/Makefile                      |   2 +-
>  drivers/counter/counter-chrdev.c              | 578 ++++++++++++++++++
>  drivers/counter/counter-chrdev.h              |  14 +
>  drivers/counter/counter-core.c                |  56 +-
>  drivers/counter/counter-sysfs.c               | 123 +++-
>  include/linux/counter.h                       |  98 +--
>  include/uapi/linux/counter.h                  | 154 +++++
>  tools/Makefile                                |  13 +-
>  tools/counter/Build                           |   1 +
>  tools/counter/Makefile                        |  53 ++
>  tools/counter/counter_example.c               |  92 +++
>  17 files changed, 1509 insertions(+), 146 deletions(-)
>  create mode 100644 drivers/counter/counter-chrdev.c
>  create mode 100644 drivers/counter/counter-chrdev.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: a5ae0cfd53aaf031c2e9ba048281776fa67047c2