Re: [PATCH v3 0/8] gpio: renesas: Add support for GPIO and related interrupts in RZ/N1 SoC

[Herve Codina <herve.codina@bootlin.com>]

Hi Conor,

On Thu, 18 Sep 2025 16:37:39 +0100
Conor Dooley <conor@kernel.org> wrote:

> On Thu, Sep 18, 2025 at 12:39:58PM +0200, Herve Codina (Schneider Electric) wrote:
> > Hi,
> > 
> > This series adds support for GPIO and GPIO IRQ mux available in the
> > RZ/N1 SoCs.
> > 
> > The first patches in this series are related to a new helper introduced
> > to parse an interrupt-map property.
> >   - patch 1: Introduce the helper (for_each_of_imap_item)
> >   - patch 2: Add a unittest for the new helper
> >   - patch 3 and 4: convert existing drivers to use this new helper
> > 
> > Patch 4 will conflicts with commit 40c26230a1bf ("irqchip: Use int type
> > to store negative error codes") available in linux-next.
> > 
> > Patch 5 adds support for GPIO (device-tree description)
> > 
> > The last patches (6, 7 and 8) of the series are related to GPIO
> > interrupts and GPIO IRQ multiplexer.
> > 
> > In the RZ/N1 SoCs, GPIO interrupts are wired to a GPIO IRQ multiplexer.
> > 
> > This multiplexer does nothing but select 8 GPIO IRQ lines out of the 96
> > available to wire them to the GIC input lines.
> > 
> > One upstreaming attempt have been done previously by Phil Edworthy [1]
> > but the series has never been applied.
> > 
> > Based on my understanding, I have fully reworked the driver proposed by
> > Phil and removed the IRQ domain. Indeed, the device doesn't handle
> > interrupts. It just routes signals.
> > 
> > Also, as an interrupt-map property is used, the driver cannot be
> > involved as an interrupt controller itself. It is a nexus node.
> > 
> > With that in mind,
> >   - Patch 6 is related to the irq-mux binding.
> > 
> >   - Patch 7 introduces the irq-mux driver.
> >     This driver uses the 'for_each_of_imap_item' helper introduced
> >     previously. Indeed, the lines routing is defined by the
> >     interrupt-map property and the driver needs to set registers to
> >     apply this routing.
> > 
> >   - Patch 8 is the RZ/N1 device-tree description update to have the
> >     support for the GPIO interrupts.
> > 
> > [1] https://lore.kernel.org/all/20190219155511.28507-1-phil.edworthy@renesas.com/
> > 
> > Best regards,
> > Hervé  
> 
> This whole thing is super interesting to me. I have a gpio irq mux of my
> own with a driver that is massively more complex than what you have here
> (it's a full on irqchip driver). I'm definitely gonna have to see if I
> can ape what you have done here and simplify what I have.

Glad to see that this is giving some ideas!

Best regards,
Hervé