Message-ID: <YS5C+cr1TRhqkCkU@shinobu>
Date:   Tue, 31 Aug 2021 23:55:53 +0900
From:   William Breathitt Gray <vilhelm.gray@...il.com>
To:     Fabrice Gasnier <fabrice.gasnier@...s.st.com>
Cc:     jic23@...nel.org, kamel.bouhara@...tlin.com, gwendal@...omium.org,
        david@...hnology.com, linux-iio@...r.kernel.org,
        patrick.havelange@...ensium.com, alexandre.belloni@...tlin.com,
        mcoquelin.stm32@...il.com, linux-kernel@...r.kernel.org,
        o.rempel@...gutronix.de, jarkko.nikula@...ux.intel.com,
        Dan Carpenter <dan.carpenter@...cle.com>,
        kernel@...gutronix.de, fabrice.gasnier@...com,
        syednwaris@...il.com, linux-stm32@...md-mailman.stormreply.com,
        linux-arm-kernel@...ts.infradead.org, alexandre.torgue@...com
Subject: Re: [Linux-stm32] [PATCH v16 03/14] counter: Internalize sysfs
 interface code

On Tue, Aug 31, 2021 at 11:16:59PM +0900, William Breathitt Gray wrote:
> On Tue, Aug 31, 2021 at 03:44:04PM +0200, Fabrice Gasnier wrote:
> > On 8/27/21 5:47 AM, William Breathitt Gray wrote:
> > > This is a reimplementation of the Generic Counter driver interface.
> > > There are no modifications to the Counter subsystem userspace interface,
> > > so existing userspace applications should continue to run seamlessly.
> > > 
> > > The purpose of this patch is to internalize the sysfs interface code
> > > among the various counter drivers into a shared module. Counter drivers
> > > pass and take data natively (i.e. u8, u64, etc.) and the shared counter
> > > module handles the translation between the sysfs interface and the
> > > device drivers. This guarantees a standard userspace interface for all
> > > counter drivers, and helps generalize the Generic Counter driver ABI in
> > > order to support the Generic Counter chrdev interface (introduced in a
> > > subsequent patch) without significant changes to the existing counter
> > > drivers.
> > > 
> > > Note, Counter device registration is the same as before: drivers
> > > populate a struct counter_device with components and callbacks, then
> > > pass the structure to the devm_counter_register function. However,
> > > what's different now is how the Counter subsystem code handles this
> > > registration internally.
> > > 
> > > Whereas before callbacks would interact directly with sysfs data, this
> > > interaction is now abstracted and instead callbacks interact with native
> > > C data types. The counter_comp structure forms the basis for Counter
> > > extensions.
> > > 
> > > The counter-sysfs.c file contains the code to parse through the
> > > counter_device structure and register the requested components and
> > > extensions. Attributes are created and populated based on type, with
> > > respective translation functions to handle the mapping between sysfs and
> > > the counter driver callbacks.
> > > 
> > > The translation performed for each attribute is straightforward: the
> > > attribute type and data is parsed from the counter_attribute structure,
> > > the respective counter driver read/write callback is called, and sysfs
> > > I/O is handled before or after the driver read/write function is called.
> > > 
> > > Cc: Jarkko Nikula <jarkko.nikula@...ux.intel.com>
> > > Cc: Patrick Havelange <patrick.havelange@...ensium.com>
> > > Cc: Kamel Bouhara <kamel.bouhara@...tlin.com>
> > > Cc: Fabrice Gasnier <fabrice.gasnier@...com>
> > > Cc: Maxime Coquelin <mcoquelin.stm32@...il.com>
> > > Cc: Alexandre Torgue <alexandre.torgue@...com>
> > > Cc: Dan Carpenter <dan.carpenter@...cle.com>
> > > Acked-by: Syed Nayyar Waris <syednwaris@...il.com>
> > > Reviewed-by: David Lechner <david@...hnology.com>
> > > Tested-by: David Lechner <david@...hnology.com>
> > > Signed-off-by: William Breathitt Gray <vilhelm.gray@...il.com>
> > > ---
> > >  MAINTAINERS                             |    1 -
> > >  drivers/counter/104-quad-8.c            |  449 +++----
> > >  drivers/counter/Makefile                |    1 +
> > >  drivers/counter/counter-core.c          |  142 +++
> > >  drivers/counter/counter-sysfs.c         |  849 +++++++++++++
> > >  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       |  179 ++-
> > >  drivers/counter/ti-eqep.c               |  180 +--
> > >  include/linux/counter.h                 |  658 +++++-----
> > >  include/linux/counter_enum.h            |   45 -
> > >  16 files changed, 1949 insertions(+), 2633 deletions(-)
> > >  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
> > > 
> > 
> > Hi William,
> > 
> > For the STM32 drivers, you can add my:
> > Reviewed-by: Fabrice Gasnier <fabrice.gasnier@...s.st.com>
> > 
> > Thanks,
> > Fabrice
> 
> Hello Fabrice,
> 
> I noticed the stm32-lptimer-cnt.c function_write() and action_write()
> callbacks do not appear to write the desired function/action
> configuration to the device. Would you check whether the device actually
> supports this functionality or if these callbacks should be removed from
> this driver.
> 
> Thanks,
> 
> William Breathitt Gray

Nevermind, I see that these configurations are sent to the device via
stm32_lptim_setup() when the counter is enabled. So that setup should be
fine after all.

Thanks,

William Breathitt Gray

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