linux-kernel - Re: IIO Device Driver for Maxim DS3502 potentiometer

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Date:   Sat, 29 Jan 2022 10:24:16 +0530
From:   jagath jogj <jagathjog1996@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc:     jic23@...nel.org, lars@...afoo.de, aardelean@...iqon.com,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: IIO Device Driver for Maxim DS3502 potentiometer

Hello Jonathan and Andy Shevchenko,

Thanks for replying.

On Fri, Jan 28, 2022 at 8:14 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Fri, Jan 28, 2022 at 10:35:54AM +0000, Jonathan Cameron wrote:
> > On Fri, 28 Jan 2022 09:11:28 +0530
> > jagath jogj <jagathjog1996@...il.com> wrote:
> >
> > > Hello,
> > >
> > > I have a Maxim DS3502 potentiometer breakout and I have written an IIO
> > > driver for learning purposes and tested with Raspberry pi and wanted
> > > to send patches of the driver for the IIO sub-system.
> > >
> > > Can I send the patches for DS3502 POT for review?
> > >
> > > The setup used to write driver
> > > Raspberry pi 3b
> > > DS3502 breakout board
> > > Raspberry pi latest kernel branch - https://github.com/raspberrypi/linux
>
> > Welcome to IIO.
> >
> > Absolutely on sending the patches for review.
> > You'll need to rebase them on latest mainline from kernel.org
> > (pick a tagged version which would currently be 5.17-rc1_

I am using raspberry pi kernel branch rpi-5.17-y which is based on
mainline tag 5.17-rc1.
Is it required to rebase the changes to the latest tag version
5.17-rc1 from kernel.org?

> >
> > and then follow the documentation for how to submit a patch in
> > https://www.kernel.org/doc/html/latest/process/submitting-patches.html

Sure I will follow the documentation for submitting a patch.
I am also learning and recently submitted a patch series of code-style
fixes to the staging branch.

> >
> > Feel free to ask if you have any questions about the process.
> >
> > Looking forwards to seeing your code.
>
> Agree with Jonathan.
>
> One remark though, can you double check that drivers/iio/potentiometer
> doesn't have any similar driver that can be expanded (usually it can be
> done by analyzing a register file of the devices, like register offsets
> and their meanings or bit fields)?

In iio/potentiometer folder the existing Maxim DS1803 is having some
differences with DS3502 like

Maxim DS1803:
Number of wipers - 2
Number of Positions - 256 - 8 bit.
Memory map having 2 volatile registers used to store wiper value.
https://datasheets.maximintegrated.com/en/ds/DS1803.pdf

Maxim DS3502:
Number of wipers - 1
Number of Positions - 128 - 7 bit.
The memory map has 2 registers to store wiper value and mode
Supports non-volatile memory to store wiper value
Supports 2 modes - Mode 0 and Mode 1
https://datasheets.maximintegrated.com/en/ds/DS3502.pdf

So thought of writing the driver for DS3502 in a separate file.
Need some advice on this whether to implement it on a separate file or
to extend the existing driver.

>
> --
> With Best Regards,
> Andy Shevchenko
>

Regards,
Jagath