[PATCH v8 3/4] gpio: rpmsg: add generic rpmsg GPIO driver

[Shenwei Wang]

> -----Original Message-----
> From: Andrew Lunn <andrew at lunn.ch>
> Sent: Tuesday, February 24, 2026 4:23 PM
> To: Shenwei Wang <shenwei.wang at nxp.com>
> Cc: Arnaud POULIQUEN <arnaud.pouliquen at foss.st.com>; Linus Walleij
> <linusw at kernel.org>; Bartosz Golaszewski <brgl at kernel.org>; Jonathan Corbet
> <corbet at lwn.net>; Rob Herring <robh at kernel.org>; Krzysztof Kozlowski
> <krzk+dt at kernel.org>; Conor Dooley <conor+dt at kernel.org>; Bjorn Andersson
> <andersson at kernel.org>; Mathieu Poirier <mathieu.poirier at linaro.org>; Frank Li
> <frank.li at nxp.com>; Sascha Hauer <s.hauer at pengutronix.de>; Shuah Khan
> <skhan at linuxfoundation.org>; linux-gpio at vger.kernel.org; linux-
> doc at vger.kernel.org; linux-kernel at vger.kernel.org; Pengutronix Kernel Team
> <kernel at pengutronix.de>; Fabio Estevam <festevam at gmail.com>; Peng Fan
> <peng.fan at nxp.com>; devicetree at vger.kernel.org; linux-
> remoteproc at vger.kernel.org; imx at lists.linux.dev; linux-arm-
> kernel at lists.infradead.org; dl-linux-imx <linux-imx at nxp.com>; Bartosz
> Golaszewski <brgl at bgdev.pl>
> Subject: Re: [EXT] Re: [PATCH v8 3/4] gpio: rpmsg: add generic rpmsg GPIO driver
> 
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> 
> > > > + remote_cm33{
> > > > +     rpmsg {
> > > > +        rpmsg-io-channel {
> > > > +          #address-cells = <1>;
> > > > +          #size-cells = <0>;
> > > > +
> > > > +          gpio at 0 {
> > > > +            compatible = "rpmsg-gpio";
> > > > +            reg = <0>;
> > > > +            gpio-controller;
> > > > +            #gpio-cells = <2>;
> > > > +            #interrupt-cells = <2>;
> > > > +            interrupt-controller;
> > > > +          };
> > > > +          gpio at 1 {
> > > > +            compatible = "rpmsg-gpio";
> > > > +            reg = <1>;
> > > > +            gpio-controller;
> > > > +            #gpio-cells = <2>;
> > > > +            #interrupt-cells = <2>;
> > > > +            interrupt-controller;
> > > > +          };
> 
> > Then how would you distinguish gpio at 0 from gpio at 1 on the CM33 RPMSG bus
> in the example above?
> > They are running on the same transport.
> 
> Doesn't reg indicate the channel number? gpio at 0 is on rpmsg channel 0. gpio at 1
> is on channel 1? The reg value gets filled into struct rpmsg_channel_info when
> the endpoints are created?

There is only a single RPMSG channel for the CM33 remoteproc in this example-its name 
is "rpmsg-io-channel". As I mentioned above, both gpio at 0 and gpio at 1 run over this same transport. 
The transport here is the RPMSG channel, so multiple GPIO controllers share that channel.

Thanks,
Shenwei

> 
>    Andrew