On Tue, Sep 7, 2021 at 11:02 PM Robert Marko [off-list ref] wrote:

On Tue, Aug 24, 2021 at 10:03 AM Robert Marko [off-list ref] wrote:

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On Wed, Aug 11, 2021 at 2:17 PM Linus Walleij [off-list ref] wrote:

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On Tue, Aug 3, 2021 at 9:23 PM Robert Marko [off-list ref] wrote:

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The pins that this driver wants to expose are used for SFP-s only,
they are provided by the Lattice CPLD which also does other things.

Linux has a generic SFP driver which is used to manage these SFP
ports, but it only supports GPIO-s, it has no concept of anything else.
Since the driver is fully generic, I have no idea how could one extend it
to effectively handle these pins internally, especially since I have more
switches that use the CPLD for SFP-s as well, even for 48 ports and 192
pins for them.

Which file is this driver in so I can look?

Hi Linus,
Sorry for the late reply.

Sure, here is the generic Linux driver that is used for SFP handling:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/phy/sfp.c?h=v5.14-rc7

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Maybe it is not a good idea to look for generic code just because
it is convenient? I have had this problem before with GPIO, along
the lines "lemme just do this dirty thing this one time because it
is so convenient for me" (more or less) and the answer is still
"no".

Can you either augment the driver to handle a regmap with bit indices
instead or write a new similar driver for that or refactor it some other
way?

It is not a simple solution to your problem, but it might be the right
solution even if it means some more work.

I understand your position, believe me, I spend some time looking at
what would be the logical way for these switches.
But I see no way how could the SFP driver be extended in a generic way
that would allow supporting different register layouts when it comes to pins.

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GPIO regmap works perfectly for this as its generic enough to cover all of
these cases.

Yeah but it might be the wrong thing to do even if it is simple
to use and works.

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CPLD also provides pins to test the port LED-s per color as well,
but I have chosen not to expose them so far.

Have you considered
Documentation/devicetree/bindings/leds/register-bit-led.txt

Yeah, but unfortunately in this case it wont work as the LED-s
are for debugging/test purposes only and you first need to switch
the CPLD out of it interpreting the LED state with a BIT flip.

Regards,
Robert

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If it is a regmap in Linux then that is fine, just pass the regmap
around inside the kernel, OK finished. But really that is an OS
detail.

Yes, its regmap but I cant really pass it to the SFP driver as I don't have
special driver handling the SFP but rather the generic kernel one.
It only knows how to handle GPIO-s.

Of course you have to program it. If I know which driver it
is it is easier to provide architecture ideas.

Yours,
Linus Walleij

Linus,

can I offer some further explanation?

Regards,
Robert

Hi Linus,

I would really like to move forward with this somehow.

I have multiple switches depending on the outcome of this series.

Regards,
Robert

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--
Robert Marko
Staff Embedded Linux Engineer
Sartura Ltd.
Lendavska ulica 16a
10000 Zagreb, Croatia
Email: robert.marko@sartura.hr
Web: www.sartura.hr

--
Robert Marko
Staff Embedded Linux Engineer
Sartura Ltd.
Lendavska ulica 16a
10000 Zagreb, Croatia
Email: robert.marko@sartura.hr
Web: www.sartura.hr

-- 
Robert Marko
Staff Embedded Linux Engineer
Sartura Ltd.
Lendavska ulica 16a
10000 Zagreb, Croatia
Email: robert.marko@sartura.hr
Web: www.sartura.hr