linux-kernel - Re: [PATCH 12/18] gpio: add support for the sl28cpld GPIO controller

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Message-ID: <021f3add4b03b7a682832921a96ef85f@walle.cc>
Date:   Mon, 30 Mar 2020 13:48:21 +0200
From:   Michael Walle <michael@...le.cc>
To:     Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio <linux-gpio@...r.kernel.org>,
        linux-devicetree <devicetree@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, linux-hwmon@...r.kernel.org,
        linux-pwm@...r.kernel.org,
        LINUXWATCHDOG <linux-watchdog@...r.kernel.org>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>,
        Rob Herring <robh+dt@...nel.org>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Lee Jones <lee.jones@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Shawn Guo <shawnguo@...nel.org>, Li Yang <leoyang.li@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <maz@...nel.org>
Subject: Re: [PATCH 12/18] gpio: add support for the sl28cpld GPIO controller

Hi,


Am 2020-03-30 13:21, schrieb Bartosz Golaszewski:
> pt., 27 mar 2020 o 16:28 Michael Walle <michael@...le.cc> napisał(a):
>> 
>> Am 2020-03-27 11:20, schrieb Linus Walleij:
>> > On Thu, Mar 26, 2020 at 9:06 PM Michael Walle <michael@...le.cc> wrote:
>> >> Am 2020-03-25 12:50, schrieb Bartosz Golaszewski:
>> >
>> >> > In that case maybe you should use the disable_locking option in
>> >> > regmap_config and provide your own callbacks that you can use in the
>> >> > irqchip code too?
>> >>
>> >> But how would that solve problem (1). And keep in mind, that the
>> >> reqmap_irqchip is actually used for the interrupt controller, which
>> >> is not this gpio controller.
>> >>
>> >> Ie. the interrupt controller of the sl28cpld uses the regmap_irqchip
>> >> and all interrupt phandles pointing to the interrupt controller will
>> >> reference the toplevel node. Any phandles pointing to the gpio
>> >> controller will reference the GPIO subnode.
>> >
>> > Ideally we would create something generic that has been on my
>> > mind for some time, like a generic GPIO regmap irqchip now that
>> > there are a few controllers like that.
>> >
>> > I don't know how feasible it is or how much work it would be. But
>> > as with GPIO_GENERIC (for MMIO) it would be helpful since we
>> > can then implement things like .set_multiple() and .get_multiple()
>> > for everyone.
>> 
>> For starters, would that be a drivers/gpio/gpio-regmap.c or a
>> drivers/base/regmap/regmap-gpio.c? I would assume the first,
>> because the stuff in drivers/base/regmap operates on a given
>> regmap and we'd just be using one, correct? On the other hand
>> there is also the reqmap-irq.c. But as pointed out before, it
>> will add an interrupt controller to the regmap, not a device
>> so to speak.
>> 
>> -michael
> 
> This has been on my TODO list for so long, but I've never been able to
> find the time... I'd really appreciate any effort in that direction as
> I believe it would allow us to slowly port a big part of the GPIO
> expander drivers over to it and make large portions of our codebase
> generic.

I might have at least a first patch this week. So if you and Linus
Walleij might have some time to help review and comment on that, it
would be greatly appreciated.

-michael

> 
> Best regards,
> Bartosz Golaszewski