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

Ard Biesheuvel
2019-05-28T13:12:49Z

On Tue, 28 May 2019 at 15:02, Lorenzo Pieralisi
<lorenzo.pieralisi@arm.com> wrote:
>
> On Mon, May 27, 2019 at 01:27:17PM +0200, 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.
>
> Nit: I do not think they are "unqualified".
>
> ACPI 6.3, table 6-237, Extended Interrupt Descriptor Definition:
>
> "Resource Source: (Optional) If present, the device that uses this
> descriptor consumes its resources from the resources produces by the
> named device object. If not present, the device consumes its resources
> out of a global pool."
>
> Where the global pool I _assume_ is the GSI domain, so it is the default
> expected behaviour (for once :))
>

By 'unqualified', I meant lacking an explicit description of the
producer of the resource. But I can change the wording if you prefer.

> > 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.
>
> Yes please comment parameters even if it is just a wrapper around
> the IRQ domain API.
>
> > +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
>
> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

Thanks,