Re: [PATCH v3 7/8] soc: renesas: Add support for Renesas RZ/N1 GPIO Interrupt Multiplexer

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

Hi Wolfram,

On Fri, 19 Sep 2025 16:40:06 +0200
Wolfram Sang <wsa+renesas@sang-engineering.com> wrote:

> > Rob asked to use only interrupt-map and use directly the interrupt-map index as
> > the hardware index:
> >   https://lore.kernel.org/lkml/20250801111753.382f52ac@bootlin.com/  
> 
> I agree with that. Currently an interrupt-map entry looks like:
> 
> 	interrupt-map = <0 &gic GIC_SPI 103 IRQ_TYPE_LEVEL_HIGH>,
> 
> And the number after GIC_SPI determines the index register, no? Can't we
> simply say 'index = <SPI_nr_from_dt> - 103' incl. some sanity checks?
> 

And so 103 used to compute the index is hardcoded on the driver.

Further more the wiring of irq-mux interrupt output to the GIC input
line depends on the irq-mux integration and not the irq-mux itself.
Nothing in the irq-mux itself requires a specific connection to the
GIC.

But well, without adding this mapping information in the DT, maybe a
table in the driver in order to determine reg index from GIC IRQ number.

kind of:
  static u8 reg_index[8] = {103, 104, 105, ... , 110};

Base on GIC IRQ number retrieve from the interrupt-map item, we search for
the index in reg_index that match this number. The index found is the index
used to access the register.

What do you think about this?

Best regards,
Hervé