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

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Date:   Fri, 27 Mar 2020 16:28:11 +0100
From:   Michael Walle <michael@...le.cc>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        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

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