linux-kernel - Re: [PATCH 4/6] of/irq: Introduce of_irq_foreach

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Message-ID: <20250730114342.665ec546@bootlin.com>
Date: Wed, 30 Jul 2025 11:43:42 +0200
From: Herve Codina <herve.codina@...tlin.com>
To: Rob Herring <robh@...nel.org>
Cc: Hoan Tran <hoan@...amperecomputing.com>, Linus Walleij
 <linus.walleij@...aro.org>, Bartosz Golaszewski <brgl@...ev.pl>, Krzysztof
 Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Geert
 Uytterhoeven <geert+renesas@...der.be>, Magnus Damm
 <magnus.damm@...il.com>, Saravana Kannan <saravanak@...gle.com>, Serge
 Semin <fancer.lancer@...il.com>, Phil Edworthy <phil.edworthy@...esas.com>,
 linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org, Miquel
 Raynal <miquel.raynal@...tlin.com>, Thomas Petazzoni
 <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH 4/6] of/irq: Introduce of_irq_foreach_imap

Hi Rob,

On Tue, 29 Jul 2025 14:51:51 -0500
Rob Herring <robh@...nel.org> wrote:

> On Fri, Jul 25, 2025 at 05:26:13PM +0200, Herve Codina wrote:
> > of_irq_foreach_imap is an iterator designed to help a driver to parse
> > an interrupt-map property.
> > 
> > Indeed some drivers need to know details about the interrupt mapping
> > described in the device-tree in order to set internal registers
> > accordingly.  
> 
> I would like to see some existing user converted to make sure it works 
> for other cases.

I will see what I can do for the next iteration.
Maybe I will propose a unit test for this new API.

> 
> > 
> > Signed-off-by: Herve Codina <herve.codina@...tlin.com>
> > ---
> >  drivers/of/irq.c       | 70 ++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/of_irq.h | 11 +++++++
> >  2 files changed, 81 insertions(+)
> > 
> > diff --git a/drivers/of/irq.c b/drivers/of/irq.c
> > index f8ad79b9b1c9..863b31eb3c1a 100644
> > --- a/drivers/of/irq.c
> > +++ b/drivers/of/irq.c
> > @@ -157,6 +157,76 @@ const __be32 *of_irq_parse_imap_parent(const __be32 *imap, int len, struct of_ph
> >  	return imap;
> >  }
> >  
> > +/**
> > + * of_irq_foreach_imap - Iterate through interrupt-map items
> > + * @np: device node where interrupt-map is available
> > + * @func: function called on each interrupt-map items
> > + * @data: data passe to @func
> > + *
> > + * This function iterates through interrupt-map items and calls @func on each
> > + * item. The parent interrupt described in the interrupt-map item is parsed
> > + * and passed to @func using a pointer to a struct of_phandle_args.
> > + * Also the imap raw value is passed in order to allow @func to look at other
> > + * values of the interrupt-map (child unit address and child interrupt
> > + * specificer)
> > + *
> > + * If @func returns an error, the iteration stops and this error is returned.
> > + */
> > +int of_irq_foreach_imap(struct device_node *np,
> > +			int (*func)(void *data,
> > +				    const __be32 *imap,
> > +				    const struct of_phandle_args *parent_args),
> > +			void *data)  
> 
> The func callback is a departure from other DT iterators. Look at the 
> 'ranges' iterator which keeps the state on each iteration.
> 

I see, I will propose a reworked version in the next iteration to have
something similar to ranges:
  - of_irq_imap_parser_init()
  - for_each_of_range() with something like
       for (; of_irq_imap_parser_one(parser, imap);)
  - of_irq_imap_parser_one()
  - of_irq_imap_parser_exit(): Not sure, will see if I need to release something

Best regards,
Hervé