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

Marc Zyngier
2019-05-28T12:54:40Z

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?

Otherwise (and with Mika's comments addressed), looks good to me.

Thanks,

M.
--
Jazz is not dead. It just smells funny...