Re: [RFC PATCH 0/3] gpio: pca953x: Redesign handling of chip types

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Thu, Feb 02, 2023 at 05:12:22PM +0200, Andy Shevchenko wrote:
> On Mon, Jan 30, 2023 at 09:59:30PM +0100, Levente Révész wrote:
> > Hi All,
> > 
> > The pca953x driver supports many chips. These all have the basic 4
> > registers: input, output, invert and direction. Most of them have
> > additional registers for various functions, like pull-up and
> > pull-down control, interrupt status and mask, hardware debounce.
> > 
> > Different chip types have various register layouts. These layouts differ
> > even in the basic 4 registers.
> > 
> > This patch series
> > 
> >     1. Cleans up chip type handling, and
> >     2. Replaces register address calculations. The proposed scheme
> >        works with every register of every chip type.
> > 
> > These changes make it possible to add support for extended functions for
> > more chip types, including:
> > 
> >     * Interrupt mask for PCA950X, PCA9698, PCA957X and XRA120X
> >     * Interrupt status for PCA957X and XRA120X
> >     * Bias for PCA957X and XRA120X
> >     * Debounce for PCAL65XX and XRA120X
> > 
> > References:
> > 1. Previous discussion about the chip types
> >    https://lore.kernel.org/linux-gpio/Y1q52efyv93%2Fz8BC@smile.fi.intel.com/
> > 2. An overview of pca953x chip types
> >    https://lore.kernel.org/linux-gpio/67bba210-09ac-32fb-bb97-8bfc40c2c200@eilabs.com/
> 
> Now as I'm thinking more of your nice job, it may be less effort to everybody
> if you start from moving the driver to be a real pin control driver united with
> GPIO handling.
> 
> That said, start drivers/pinctrl/pinctrl-pca953x.c from scratch with all your
> ideas in it. To make it better for review and testing, split by series in which
> you add the main chip family, i.e. PCA953x one (without interrupt?) and then
> adding each type one-by-one.
> 
> Also prepare some documentation file in Documentation/...gpio.../pca953x or
> start a brand new pinctrl folder (we do not have it yet) where you describe
> all your research.
> 
> Note, this will be quite useful to enable PWM support later on for some chips.

And to avoid messing up with the existing driver, add Kconfig part at last.

-- 
With Best Regards,
Andy Shevchenko