On Sat, 03 Mar 2012 21:09:32 -0800, David Daney <david.s.daney@xxxxxxxxx> wrote:
> On 03/03/2012 11:35 AM, Rob Herring wrote:
> > On 03/02/2012 01:29 PM, David Daney wrote:
> >> On 03/02/2012 11:07 AM, Grant Likely wrote:
> >>> +static void __init octeon_irq_set_ciu_mapping(unsigned int irq,
> >>> + unsigned int line,
> >>> + unsigned int bit,
> >>> + struct irq_domain *domain,
> >>> struct irq_chip *chip,
> >>> irq_flow_handler_t handler)
> >>> {
> >>> + struct irq_data *irqd;
> >>> union octeon_ciu_chip_data cd;
> >>>
> >>> irq_set_chip_and_handler(irq, chip, handler);
> >>> -
> >>> cd.l = 0;
> >>> cd.s.line = line;
> >>> cd.s.bit = bit;
> >>>
> >>> irq_set_chip_data(irq, cd.p);
> >>> octeon_irq_ciu_to_irq[line][bit] = irq;
> >>> +
> >>> + irqd = irq_get_irq_data(irq);
> >>> + irqd->hwirq = line<< 6 | bit;
> >>> + irqd->domain = domain;
> >>>>> I think the domain code will set these.
> >>>> It is my understanding that the domain code only does this for:
> >>>>
> >>>> o irq_domain_add_legacy()
> >>>>
> >>>> o irq_create_direct_mapping()
> >>>>
> >>>> o irq_create_mapping()
> >>>>
> >>>> We use none of those. So I do it here.
> >>>>
> >>>> If there is a better way, I am open to suggestions.
> >>> irq_create_mapping is called by irq_create_of_mapping() which is
> >>> in turn called by irq_of_parse_and-map(). irq_domain always
> >>> manages the hwirq and domain values. Driver code cannot manipulate
> >>> them manually.
> >>>
> >> I really must be missing something.
> >>
> >> Given:
> >>
> >> 1) I must have a mapping between hwirq and irq that I control so that
> >> non-OF code using the OCTEON_IRQ_* constants continues to work.
> > Those defines are what you need to work to get rid of.
>
> We are not starting from a blank slate here. There is a lot of in-tree
> code using these symbols. We cannot make them disappear with wishful
> thinking.
>
> The first step is a switch to irq_domains using the existing mappings.
>
> After we do that, I have patches to transition some drivers to use the
> OF mapping via irq_domains. After those are merged, we can work toward
> getting rid of OCTEON_IRQ_*. But I think it must be the last step in
> the process, not the first.
> >
> >> 2) irq_create_mapping() will allocate a random irq value if none is
> >> already assigned to the hwirq.
> >>
> >> Therefore: To avoid having random irq values assigned, I must manually
> >> assign them.
> >>
> > So you should be using legacy domain if you need to maintain fixed hwirq
> > to linux irq numbers. "linear" is a bit confusing as it doesn't mean
> > linear 1:1 irq number assignment, but linear search.
>
> My reading of Grant's code in linux-next directly contradicts this
> statement. There is no code in irqdomain.c, that I can see, that allows
> me to have an arbitrary mapping of irq <--> hwirq values.
There are 4 kinds of mappings available; legacy, linear, radix and nomap.
Ignore nomap and radix; you don't want them.
legacy maps a contiguous range of hwirq numbers to a contiguous range of
linux irq numbers. To preserve the exising #define mappings but still add
DT support, this is the one that you want. The downside is that it requires
all the irq_descs to be allocated ahead of time (which probably isn't a
problem for you).
The linear map has a linear reverse map lookup table that allows arbitrary
irq <--> hwirq mappings. This mapping is preferred, but it doesn't work
if you need to preserve #defined irq mappings.
g.
