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[PATCH 1/2] irqdomain: support three-cell scheme interrupts

Yixun Lan posted 2 patches 11 months, 2 weeks ago
There is a newer version of this series
[PATCH 1/2] irqdomain: support three-cell scheme interrupts
Posted by Yixun Lan 11 months, 2 weeks ago 
The is a prerequisite patch to support parsing three-cell
interrupts which encoded as <instance hwirq irqflag>,
the translate function will always retrieve irq number and
flag from last two cells.

Signed-off-by: Yixun Lan <dlan@gentoo.org>
---
 kernel/irq/irqdomain.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index ec6d8e72d980f604ded2bfa2143420e0e0095920..cb874ab5e54a4763d601122becd63b6d759e55d2 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -1208,10 +1208,17 @@ int irq_domain_translate_twocell(struct irq_domain *d,
 				 unsigned long *out_hwirq,
 				 unsigned int *out_type)
 {
+	u32 irq, type;
+
 	if (WARN_ON(fwspec->param_count < 2))
 		return -EINVAL;
-	*out_hwirq = fwspec->param[0];
-	*out_type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
+
+	irq = fwspec->param_count - 2;
+	type = fwspec->param_count - 1;
+
+	*out_hwirq = fwspec->param[irq];
+	*out_type = fwspec->param[type] & IRQ_TYPE_SENSE_MASK;
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(irq_domain_translate_twocell);

-- 
2.48.1
Re: [PATCH 1/2] irqdomain: support three-cell scheme interrupts
Posted by Alex Elder 11 months, 2 weeks ago 
On 2/27/25 5:24 AM, Yixun Lan wrote:
> The is a prerequisite patch to support parsing three-cell
> interrupts which encoded as <instance hwirq irqflag>,
> the translate function will always retrieve irq number and
> flag from last two cells.
> 
> Signed-off-by: Yixun Lan <dlan@gentoo.org>
> ---
>   kernel/irq/irqdomain.c | 11 +++++++++--
>   1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> index ec6d8e72d980f604ded2bfa2143420e0e0095920..cb874ab5e54a4763d601122becd63b6d759e55d2 100644
> --- a/kernel/irq/irqdomain.c
> +++ b/kernel/irq/irqdomain.c
> @@ -1208,10 +1208,17 @@ int irq_domain_translate_twocell(struct irq_domain *d,
>   				 unsigned long *out_hwirq,
>   				 unsigned int *out_type)
>   {

This function is meant for "twocell".  There is also another function
irq_domain_translate_onecell().  Why don't you just create
irq_domain_translate_threecell" instead?

					-Alex


> +	u32 irq, type;
> +
>   	if (WARN_ON(fwspec->param_count < 2))
>   		return -EINVAL;
> -	*out_hwirq = fwspec->param[0];
> -	*out_type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
> +
> +	irq = fwspec->param_count - 2;
> +	type = fwspec->param_count - 1;
> +
> +	*out_hwirq = fwspec->param[irq];
> +	*out_type = fwspec->param[type] & IRQ_TYPE_SENSE_MASK;
> +
>   	return 0;
>   }
>   EXPORT_SYMBOL_GPL(irq_domain_translate_twocell);
>
Re: [PATCH 1/2] irqdomain: support three-cell scheme interrupts
Posted by Yixun Lan 11 months, 2 weeks ago 
On 10:12 Thu 27 Feb     , Alex Elder wrote:
> On 2/27/25 5:24 AM, Yixun Lan wrote:
> > The is a prerequisite patch to support parsing three-cell
> > interrupts which encoded as <instance hwirq irqflag>,
> > the translate function will always retrieve irq number and
> > flag from last two cells.
> > 
> > Signed-off-by: Yixun Lan <dlan@gentoo.org>
> > ---
> >   kernel/irq/irqdomain.c | 11 +++++++++--
> >   1 file changed, 9 insertions(+), 2 deletions(-)
> > 
> > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> > index ec6d8e72d980f604ded2bfa2143420e0e0095920..cb874ab5e54a4763d601122becd63b6d759e55d2 100644
> > --- a/kernel/irq/irqdomain.c
> > +++ b/kernel/irq/irqdomain.c
> > @@ -1208,10 +1208,17 @@ int irq_domain_translate_twocell(struct irq_domain *d,
> >   				 unsigned long *out_hwirq,
> >   				 unsigned int *out_type)
> >   {
> 
> This function is meant for "twocell".  There is also another function
> irq_domain_translate_onecell().  Why don't you just create
> irq_domain_translate_threecell" instead?
> 
good question!

it's too many changes for adding "threecell" which I thought not worth
the effort, or maybe we can rename the function to *twothreecell()?

I'm not sure which way to go is the best, ideas from maintainer are
welcome

> 
> > +	u32 irq, type;
> > +
> >   	if (WARN_ON(fwspec->param_count < 2))
> >   		return -EINVAL;
> > -	*out_hwirq = fwspec->param[0];
> > -	*out_type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
> > +
> > +	irq = fwspec->param_count - 2;
> > +	type = fwspec->param_count - 1;
no matter two or three cell, it's always parse the last two cells,
virtually they are same syntax, which can reuse the *_translate_twocell()
function perfectly..

> > +
> > +	*out_hwirq = fwspec->param[irq];
> > +	*out_type = fwspec->param[type] & IRQ_TYPE_SENSE_MASK;
> > +
> >   	return 0;
> >   }
> >   EXPORT_SYMBOL_GPL(irq_domain_translate_twocell);
> > 
> 

-- 
Yixun Lan (dlan)
Gentoo Linux Developer
GPG Key ID AABEFD55
Re: [PATCH 1/2] irqdomain: support three-cell scheme interrupts
Posted by Thomas Gleixner 11 months, 2 weeks ago 
On Thu, Feb 27 2025 at 20:41, Yixun Lan wrote:
> On 10:12 Thu 27 Feb     , Alex Elder wrote:
>> On 2/27/25 5:24 AM, Yixun Lan wrote:
>> > 
>> > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
>> > index ec6d8e72d980f604ded2bfa2143420e0e0095920..cb874ab5e54a4763d601122becd63b6d759e55d2 100644
>> > --- a/kernel/irq/irqdomain.c
>> > +++ b/kernel/irq/irqdomain.c
>> > @@ -1208,10 +1208,17 @@ int irq_domain_translate_twocell(struct irq_domain *d,
>> >   				 unsigned long *out_hwirq,
>> >   				 unsigned int *out_type)
>> >   {
>> 
>> This function is meant for "twocell".  There is also another function
>> irq_domain_translate_onecell().  Why don't you just create
>> irq_domain_translate_threecell" instead?
>> 
> good question!
>
> it's too many changes for adding "threecell" which I thought not worth
> the effort, or maybe we can rename the function to *twothreecell()?
>
> I'm not sure which way to go is the best, ideas from maintainer are
> welcome

We really want to have explicit functions for two and three cells.
 
>> > +	u32 irq, type;
>> > +
>> >   	if (WARN_ON(fwspec->param_count < 2))
>> >   		return -EINVAL;
>> > -	*out_hwirq = fwspec->param[0];
>> > -	*out_type = fwspec->param[1] & IRQ_TYPE_SENSE_MASK;
>> > +
>> > +	irq = fwspec->param_count - 2;
>> > +	type = fwspec->param_count - 1;
> no matter two or three cell, it's always parse the last two cells,
> virtually they are same syntax, which can reuse the *_translate_twocell()
> function perfectly..

Yes, that works but the code is completely non-obvious. So what you
really want is something like this:

int irq_domain_translate_cells(struct irq_domain *d, unsigned long *hwirq,
			       unsigned int *type)
{
        unsigned int cells = fwspec->param_count;

        switch (cells) {
       	case 1:
                *hwirq = fwspec->param[0];
                *type = IRQ_TYPE_NONE;
                return 0;
       	case 2..3:
	        /*
        	 * For multi cell translations the hardware interrupt number and type
	         * are in the last two cells.
	         */
		*hwirq = fwspec->param[cells - 2];
        	*type = fwspec->param[cells - 1] & IRQ_TYPE_SENSE_MASK;
                return 0;
        default:
   		return -EINVAL;
        }
}

Then have inline helpers:

static inline int irq_domain_translate_XXXcell(struct irq_domain *d, unsigned long *hwirq,
					       unsigned int *type)
{
        return irq_domain_translate_cells(d, hwirq, type);
}

That avoids changing all call sites at once and merges the one cell
translation into it.

You get the idea....

Thanks,

        tglx
Re: [PATCH 1/2] irqdomain: support three-cell scheme interrupts
Posted by Linus Walleij 11 months, 2 weeks ago 
On Thu, Feb 27, 2025 at 9:42 PM Yixun Lan <dlan@gentoo.org> wrote:

> > This function is meant for "twocell".  There is also another function
> > irq_domain_translate_onecell().  Why don't you just create
> > irq_domain_translate_threecell" instead?
> >
> good question!
>
> it's too many changes for adding "threecell" which I thought not worth
> the effort, or maybe we can rename the function to *twothreecell()?
>
> I'm not sure which way to go is the best, ideas from maintainer are
> welcome

Yeah just rename it twothreecell, that's fine, we will understand it :)

Thanks for driving this change, much appreciated!

Yours,
Linus Walleij
Re: [PATCH 1/2] irqdomain: support three-cell scheme interrupts
Posted by Yixun Lan 11 months, 2 weeks ago 
Hi Linus Walleij:

On 09:44 Fri 28 Feb     , Linus Walleij wrote:
> On Thu, Feb 27, 2025 at 9:42 PM Yixun Lan <dlan@gentoo.org> wrote:
> 
> > > This function is meant for "twocell".  There is also another function
> > > irq_domain_translate_onecell().  Why don't you just create
> > > irq_domain_translate_threecell" instead?
> > >
> > good question!
> >
> > it's too many changes for adding "threecell" which I thought not worth
> > the effort, or maybe we can rename the function to *twothreecell()?
> >
> > I'm not sure which way to go is the best, ideas from maintainer are
> > welcome
> 
> Yeah just rename it twothreecell, that's fine, we will understand it :)
> 
there will be quite a lot files to touch, which looks a little bit scary
but anyway, I'm fine with either way..

$ git grep irq_domain_translate_twocell | cut -f 1 -d ':' | sort -u | wc -l
11

Thomas Gleixner, do you agree with this direction? then I can work on it

-- 
Yixun Lan (dlan)
Gentoo Linux Developer
GPG Key ID AABEFD55

Patchew 2.1-devel-b67e4c2

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