From: AKASHI Takahiro <takahiro.akashi@linaro.org>
To: Cristian Marussi <cristian.marussi@arm.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Rob Herring <robh@kernel.org>,
sudeep.holla@arm.com, krzysztof.kozlowski+dt@linaro.org,
conor+dt@kernel.org, Oleksii_Moisieiev@epam.com,
linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org
Subject: Re: [RFC v2 5/5] dt-bindings: gpio: Add bindings for pinctrl based generic gpio driver
Date: Tue, 10 Oct 2023 14:14:37 +0900 [thread overview]
Message-ID: <ZSTdvROVzJU5FRAZ@octopus> (raw)
In-Reply-To: <ZSQXXW1NRiCpsENu@e120937-lin>
On Mon, Oct 09, 2023 at 04:08:13PM +0100, Cristian Marussi wrote:
> On Mon, Oct 09, 2023 at 03:13:24PM +0200, Linus Walleij wrote:
> > On Mon, Oct 9, 2023 at 11:08???AM Cristian Marussi
> > <cristian.marussi@arm.com> wrote:
> >
> > > > > + gpio0: gpio@0 {
> > > > > + compatible = "pin-control-gpio";
> > > > > + gpio-controller;
> > > > > + #gpio-cells = <2>;
> > > > > + gpio-ranges = <&scmi_pinctrl 0 10 5>,
> > > > > + <&scmi_pinctrl 5 0 0>;
> > > > > + gpio-ranges-group-names = "",
> > > > > + "pinmux_gpio";
> > > > > + };
> > > >
> > >
> > > Assuming the above &scmi_pinctrl refers to the protocol node as we
> > > usually do,
> >
> > No it does not, it is a three-layer cake.
> >
> > scmi <-> scmi_pinctrl <-> scmi_gpio
> >
> > it refers to the scmi_pinctrl node.
> >
>
> Thanks, this explains a lot.
> Cristian
Just in case,
gpio-ranges = <&scmi_pinctrl 0 10 5>;
means that SCMI *pin* range [10..(10+5-1)] are mapped to this driver's
gpio range [0..(5-1)]. So any consumer driver can access a gpio pin
as:
foo-gpios = <&gpio0 3>;
will refer to gpio pin#3 that is actually SCMI's 13.
gpio-ranges = <&scmi_pinctrl 5 0 0>;
gpio-ranges-group-names = "pinmux_gpio";
means that SCMI *group*, "pinmux_gpio", are mapped to this driver's
gpio range which starts with 5. If "pinmux_gpio" indicates SCMI *pin*
range [20..24],
baa-gpios = <&gpio0 7>;
will refer to gpio pin#7 that is actually SCMI's 22 (=20 + (7-5)).
This way, we (consumer drivers) don't care what is the underlying pin
controller.
-Takahiro Akashi
>
> > There is no SCMI GPIO protocol, instead SCMI is using the
> > operations already available in the pin controller to exercise
> > GPIO. Generic pin control has operations to drive lines for
> > example, and Takahiro is adding the ability for a generic pin
> > controller to also read a line.
>
>
> >
> > Yours,
> > Linus Walleij
next prev parent reply other threads:[~2023-10-10 5:14 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-05 2:58 [RFC v2 0/5] gpio: add pinctrl based generic gpio driver AKASHI Takahiro
2023-10-05 2:58 ` [RFC v2 1/5] pinctrl: define PIN_CONFIG_INPUT AKASHI Takahiro
2023-10-10 11:53 ` Linus Walleij
2023-10-05 2:58 ` [RFC v2 2/5] pinctrl: always export pin_config_get_for_pin() AKASHI Takahiro
2023-10-10 11:54 ` Linus Walleij
2023-10-05 2:58 ` [RFC v2 3/5] pinctrl: add pinctrl_gpio_get_config() AKASHI Takahiro
2023-10-05 2:58 ` [RFC v2 4/5] gpio: add pinctrl based generic gpio driver AKASHI Takahiro
2023-10-10 12:00 ` Linus Walleij
2023-10-12 1:08 ` AKASHI Takahiro
2023-10-05 2:58 ` [RFC v2 5/5] dt-bindings: gpio: Add bindings for " AKASHI Takahiro
2023-10-05 19:48 ` Krzysztof Kozlowski
2023-10-12 1:15 ` AKASHI Takahiro
2023-10-12 7:27 ` Krzysztof Kozlowski
2023-10-06 13:18 ` Rob Herring
2023-10-06 13:23 ` Rob Herring
2023-10-09 7:49 ` Linus Walleij
2023-10-09 9:08 ` Cristian Marussi
2023-10-09 13:13 ` Linus Walleij
2023-10-09 15:08 ` Cristian Marussi
2023-10-10 5:14 ` AKASHI Takahiro [this message]
2023-10-10 5:25 ` AKASHI Takahiro
2023-10-12 7:25 ` Linus Walleij
2023-10-17 2:32 ` AKASHI Takahiro
2023-10-23 8:12 ` Linus Walleij
2023-10-24 7:12 ` AKASHI Takahiro
2023-10-24 9:40 ` Linus Walleij
2023-10-24 10:55 ` Cristian Marussi
2023-10-24 13:01 ` Linus Walleij
2023-10-24 11:09 ` AKASHI Takahiro
2023-10-24 13:12 ` Linus Walleij
2023-10-24 13:42 ` AKASHI Takahiro
2023-11-05 22:15 ` Linus Walleij
2023-10-19 21:27 ` [RFC v2 0/5] gpio: add " andy.shevchenko
2023-10-20 0:21 ` AKASHI Takahiro
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