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    SubjectRe: [PATCH 6/8] irqdomain: Support identity mapped VIRQ allocation.
    Date
    On Sat, 19 May 2012 15:11:46 +0900, Paul Mundt <lethal@linux-sh.org> wrote:
    > This adds a new irq_create_identity_mapping() routine to permit platforms
    > to utilize 1:1 identity mapping between hardware and linux IRQs for
    > domain population. The same semantics as irq_create_mapping() apply,
    > though in this case we only support irqdesc allocation at a static
    > location, rather than falling back on dynamic lookup.
    >
    > Signed-off-by: Paul Mundt <lethal@linux-sh.org>
    > ---
    > include/linux/irqdomain.h | 2 ++
    > kernel/irq/irqdomain.c | 41 +++++++++++++++++++++++++++++++++++++++++
    > 2 files changed, 43 insertions(+), 0 deletions(-)
    >
    > diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
    > index 5abb533..e32d2e7 100644
    > --- a/include/linux/irqdomain.h
    > +++ b/include/linux/irqdomain.h
    > @@ -149,6 +149,8 @@ extern unsigned int irq_create_mapping(struct irq_domain *host,
    > extern void irq_dispose_mapping(unsigned int virq);
    > extern unsigned int irq_find_mapping(struct irq_domain *host,
    > irq_hw_number_t hwirq);
    > +extern unsigned int irq_create_identity_mapping(struct irq_domain *host,
    > + irq_hw_number_t hwirq);
    > extern unsigned int irq_create_direct_mapping(struct irq_domain *host);
    > extern void irq_radix_revmap_insert(struct irq_domain *host, unsigned int virq,
    > irq_hw_number_t hwirq);
    > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
    > index 5f0ca52..ac44781 100644
    > --- a/kernel/irq/irqdomain.c
    > +++ b/kernel/irq/irqdomain.c
    > @@ -459,6 +459,47 @@ unsigned int irq_create_mapping(struct irq_domain *domain,
    > }
    > EXPORT_SYMBOL_GPL(irq_create_mapping);
    >
    > +/**
    > + * irq_create_identity_mapping() - Allocate an identity mapped irq
    > + * @domain: domain owning this hardware interrupt or NULL for default domain
    > + * @hwirq: hardware irq number in that domain space
    > + *
    > + * This routine is used to allocate IRQs with a 1:1 identity mapping
    > + * between the hardware and linux irq.
    > + */
    > +unsigned int irq_create_identity_mapping(struct irq_domain *domain,
    > + irq_hw_number_t hwirq)

    How about the following for an API (omitting error checking, and the
    actual names are up for debate):

    int irq_domain_associate_many(struct irq_domain *domain,
    unsigned int irq_base,
    irq_hw_number_t hwirq_base,
    int count)
    {
    int i;
    for (i = 0; i < count; i++)
    irq_setup_virq(domain, irq_base + i, hwirq_base + i);
    }
    int irq_create_strict_mappings(struct irq_domain *domain,
    unsigned int irq_base,
    irq_hw_number_t hwirq_base,
    int count)
    {
    /* Allows for non-identity, but still static mappings of a
    * range of irq numbers */
    irq_alloc_descs(irq_base, irq_base, irq_domain_nid(domain->of_node));
    irq_domain_associate_many(domain, irq_base, hwirq, count);
    ...
    }

    /* in header */
    static int irq_create_identity_mapping(struct irq_domain *domain,
    irq_hw_number_t hwirq_base)
    {
    irq_create_strict_mappings(domain, hwirq_base, hwirq_base, 1);
    }

    That would give the ability to either associated for pre-allocated
    irq_descs, or strict map for allocating a specific range of irqs.


    > +{
    > + int virq;
    > +
    > + pr_debug("irq: irq_create_identity_mapping(0x%p, 0x%lx)\n",
    > + domain, hwirq);
    > +
    > + if (domain == NULL)
    > + domain = irq_default_domain;

    This is a new API, and I'm not a fan of the irq_default_domain usage
    so I'd like just drop the above too lines. My opinion is that if your
    calling into get a mapping, then the code really should know what
    domain it is requesting from. If a default domain really is needed,
    then there it should be explicit for the caller to find the default
    domain and then pass that in to this function.

    > + if (domain == NULL) {
    > + WARN_ON(1);
    > + return 0;
    > + }
    > +
    > + virq = irq_alloc_desc_at(hwirq, irq_domain_nid(domain->of_node));
    > + if (virq < 0) {
    > + pr_debug("irq: -> virq allocation failed\n");
    > + return 0;
    > + }
    > +
    > + if (irq_setup_virq(domain, virq, hwirq)) {
    > + if (domain->revmap_type != IRQ_DOMAIN_MAP_LEGACY)
    > + irq_free_desc(virq);
    > + return 0;
    > + }
    > +
    > + pr_debug("irq: irq %lu identity mapped\n", hwirq);
    > +
    > + return virq;
    > +}
    > +EXPORT_SYMBOL_GPL(irq_create_identity_mapping);
    > +
    > unsigned int irq_create_of_mapping(struct device_node *controller,
    > const u32 *intspec, unsigned int intsize)
    > {
    > --
    > 1.7.9.rc0.28.g0e1cf
    >
    > --
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    --
    Grant Likely, B.Sc, P.Eng.
    Secret Lab Technologies, Ltd.


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