Re: [PATCH v3 1/4] acpi/irq: implement helper to create hierachical domains

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On Tue, 28 May 2019 at 14:54, Marc Zyngier <marc.zyngier@arm.com> wrote:
>
> Hi Ard,
>
> On 27/05/2019 12:27, Ard Biesheuvel wrote:
> > ACPI permits arbitrary producer->consumer interrupt links to be
> > described in AML, which means a topology such as the following
> > is perfectly legal:
> >
> >   Device (EXIU) {
> >     Name (_HID, "SCX0008")
> >     Name (_UID, Zero)
> >     Name (_CRS, ResourceTemplate () {
> >       ...
> >     })
> >   }
> >
> >   Device (GPIO) {
> >     Name (_HID, "SCX0007")
> >     Name (_UID, Zero)
> >     Name (_CRS, ResourceTemplate () {
> >       Memory32Fixed (ReadWrite, SYNQUACER_GPIO_BASE, SYNQUACER_GPIO_SIZE)
> >       Interrupt (ResourceConsumer, Edge, ActiveHigh, ExclusiveAndWake, 0, "\\_SB.EXIU") {
> >         7,
> >       }
> >     })
> >     ...
> >   }
> >
> > The EXIU in this example is the external interrupt unit as can be found
> > on Socionext SynQuacer based platforms, which converts a block of 32 SPIs
> > from arbitrary polarity/trigger into level-high, with a separate set
> > of config/mask/unmask/clear controls.
> >
> > The existing DT based driver in drivers/irqchip/irq-sni-exiu.c models
> > this as a hierarchical domain stacked on top of the GIC's irqdomain.
> > Since the GIC is modeled as a DT node as well, obtaining a reference
> > to this irqdomain is easily done by going through the parent link.
> >
> > On ACPI systems, however, the GIC is not modeled as an object in the
> > namespace, and so device objects cannot refer to it directly. So in
> > order to obtain the irqdomain reference when driving the EXIU in ACPI
> > mode, we need a helper that implicitly grabs the default domain for
> > unqualified interrupts as the parent of the hierarchy.
> >
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > ---
> >  drivers/acpi/irq.c   | 20 ++++++++++++++++++++
> >  include/linux/acpi.h |  7 +++++++
> >  2 files changed, 27 insertions(+)
> >
> > diff --git a/drivers/acpi/irq.c b/drivers/acpi/irq.c
> > index c3b2222e2129..39824a6bbcd5 100644
> > --- a/drivers/acpi/irq.c
> > +++ b/drivers/acpi/irq.c
> > @@ -295,3 +295,23 @@ void __init acpi_set_irq_model(enum acpi_irq_model_id model,
> >       acpi_irq_model = model;
> >       acpi_gsi_domain_id = fwnode;
> >  }
> > +
> > +/**
> > + * acpi_irq_create_hierarchy - Create a hierarchical IRQ domain with the default
> > + *                             GSI domain as its parent.
> > + */
> > +struct irq_domain *acpi_irq_create_hierarchy(unsigned int flags,
> > +                                          unsigned int size,
> > +                                          struct fwnode_handle *fwnode,
> > +                                          const struct irq_domain_ops *ops,
> > +                                          void *host_data)
> > +{
> > +     struct irq_domain *d = irq_find_matching_fwnode(acpi_gsi_domain_id,
> > +                                                     DOMAIN_BUS_ANY);
> > +
> > +     if (!d)
> > +             return NULL;
> > +
> > +     return irq_domain_create_hierarchy(d, flags, size, fwnode, ops,
> > +                                        host_data);
> > +}
> > diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> > index 98440df7fe42..70de4bc30cea 100644
> > --- a/include/linux/acpi.h
> > +++ b/include/linux/acpi.h
> > @@ -23,6 +23,7 @@
> >
> >  #include <linux/errno.h>
> >  #include <linux/ioport.h>    /* for struct resource */
> > +#include <linux/irqdomain.h>
> >  #include <linux/resource_ext.h>
> >  #include <linux/device.h>
> >  #include <linux/property.h>
> > @@ -327,6 +328,12 @@ int acpi_isa_irq_to_gsi (unsigned isa_irq, u32 *gsi);
> >  void acpi_set_irq_model(enum acpi_irq_model_id model,
> >                       struct fwnode_handle *fwnode);
> >
> > +struct irq_domain *acpi_irq_create_hierarchy(unsigned int flags,
> > +                                          unsigned int size,
> > +                                          struct fwnode_handle *fwnode,
> > +                                          const struct irq_domain_ops *ops,
> > +                                          void *host_data);
> > +
> >  #ifdef CONFIG_X86_IO_APIC
> >  extern int acpi_get_override_irq(u32 gsi, int *trigger, int *polarity);
> >  #else
> >
>
> Should we consider exporting this function to modules?
>

Good point, we probably should.


> Otherwise (and with Mika's comments addressed), looks good to me.
>
> Thanks,
>
>         M.
> --
> Jazz is not dead. It just smells funny...