[PATCH v8 15/21] ARM64 / ACPI: Introduce ACPI_IRQ_MODEL_GIC and register device's gsi

Will Deacon
2015-02-09T07:07:54Z

On Mon, Feb 09, 2015 at 06:53:31AM +0000, Hanjun Guo wrote:
> On 2015?02?09? 14:34, Will Deacon wrote:
> > On Mon, Feb 02, 2015 at 12:45:43PM +0000, Hanjun Guo wrote:
> >> Introduce ACPI_IRQ_MODEL_GIC which is needed for ARM64 as GIC is
> >> used, and then register device's gsi with the core IRQ subsystem.
> >>
> >> acpi_register_gsi() is similar to DT based irq_of_parse_and_map(),
> >> since gsi is unique in the system, so use hwirq number directly
> >> for the mapping.
> >>
> >> We are going to implement stacked domains when GICv2m, GICv3, ITS
> >> support are added.
> >>
> >> CC: Marc Zyngier <marc.zyngier@arm.com>
> >> Originally-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
> >> Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
> >> Tested-by: Yijing Wang <wangyijing@huawei.com>
> >> Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
> >> Tested-by: Jon Masters <jcm@redhat.com>
> >> Tested-by: Timur Tabi <timur@codeaurora.org>
> >> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> >> ---
> >> arch/arm64/kernel/acpi.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++
> >> drivers/acpi/bus.c | 3 ++
> >> include/linux/acpi.h | 1 +
> >> 3 files changed, 77 insertions(+)
> >>
> >> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> >> index f80caef..f86a982 100644
> >> --- a/arch/arm64/kernel/acpi.c
> >> +++ b/arch/arm64/kernel/acpi.c
> >> @@ -38,6 +38,12 @@ EXPORT_SYMBOL(acpi_pci_disabled);
> >> static int enabled_cpus; /* Processors (GICC) with enabled flag in MADT */
> >>
> >> /*
> >> + * Since we're on ARM, the default interrupt routing model
> >> + * clearly has to be GIC.
> >> + */
> >> +enum acpi_irq_model_id acpi_irq_model = ACPI_IRQ_MODEL_GIC;
> >> +
> >> +/*
> >> * __acpi_map_table() will be called before page_init(), so early_ioremap()
> >> * or early_memremap() should be called here to for ACPI table mapping.
> >> */
> >> @@ -185,6 +191,73 @@ void __init acpi_init_cpus(void)
> >> pr_info("%d CPUs enabled, %d CPUs total\n", enabled_cpus, total_cpus);
> >> }
> >>
> >> +int acpi_gsi_to_irq(u32 gsi, unsigned int *irq)
> >> +{
> >> + *irq = irq_find_mapping(NULL, gsi);
> >> +
> >> + return 0;
> >> +}
> >> +EXPORT_SYMBOL_GPL(acpi_gsi_to_irq);
> >> +
> >> +/*
> >> + * success: return IRQ number (>0)
> >> + * failure: return =< 0
> >> + */
> >> +int acpi_register_gsi(struct device *dev, u32 gsi, int trigger, int polarity)
> >> +{
> >> + unsigned int irq;
> >> + unsigned int irq_type;
> >> +
> >> + /*
> >> + * ACPI have no bindings to indicate SPI or PPI, so we
> >> + * use different mappings from DT in ACPI.
> >> + *
> >> + * For FDT
> >> + * PPI interrupt: in the range [0, 15];
> >> + * SPI interrupt: in the range [0, 987];
> >> + *
> >> + * For ACPI, GSI should be unique so using
> >> + * the hwirq directly for the mapping:
> >> + * PPI interrupt: in the range [16, 31];
> >> + * SPI interrupt: in the range [32, 1019];
> >> + */
> >> +
> >> + if (trigger == ACPI_EDGE_SENSITIVE &&
> >> + polarity == ACPI_ACTIVE_LOW)
> >> + irq_type = IRQ_TYPE_EDGE_FALLING;
> >> + else if (trigger == ACPI_EDGE_SENSITIVE &&
> >> + polarity == ACPI_ACTIVE_HIGH)
> >> + irq_type = IRQ_TYPE_EDGE_RISING;
> >> + else if (trigger == ACPI_LEVEL_SENSITIVE &&
> >> + polarity == ACPI_ACTIVE_LOW)
> >> + irq_type = IRQ_TYPE_LEVEL_LOW;
> >> + else if (trigger == ACPI_LEVEL_SENSITIVE &&
> >> + polarity == ACPI_ACTIVE_HIGH)
> >> + irq_type = IRQ_TYPE_LEVEL_HIGH;
> >> + else
> >> + irq_type = IRQ_TYPE_NONE;
> >> +
> >> + /*
> >> + * Since only one GIC is supported in ACPI 5.0, we can
> >> + * create mapping refer to the default domain
> >> + */
> >> + irq = irq_create_mapping(NULL, gsi);
> >> + if (!irq)
> >> + return irq;
> >> +
> >> + /* Set irq type if specified and different than the current one */
> >> + if (irq_type != IRQ_TYPE_NONE &&
> >> + irq_type != irq_get_trigger_type(irq))
> >> + irq_set_irq_type(irq, irq_type);
> >> + return irq;
> >> +}
> >> +EXPORT_SYMBOL_GPL(acpi_register_gsi);
> >> +
> >> +void acpi_unregister_gsi(u32 gsi)
> >> +{
> >> +}
> >> +EXPORT_SYMBOL_GPL(acpi_unregister_gsi);
> >> +
> >> static int __init acpi_parse_fadt(struct acpi_table_header *table)
> >> {
> >> struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
> >
> > Does this code *have* to sit under arch/arm64? I can't see anything
> > architecture-specific about it and the bulk of the functions map directly
> > onto irq domain callbacks. I know that the answer is probably "we can fix
> > that in the future", but it doesn't seem like a huge amount of effort to
> > get the right abstractions in place from the beginning so that we don't
> > have to churn this stuff later on.
>
> Do you mean move acpi_register_gsi()/acpi_unregister_gsi() to irqdomain
> related file?
>
> Since x86 and IA64 have their arch specific acpi_register_gsi()
> /acpi_unregister_gsi(), we will got compile errors on x86 and IA64
> platforms.

Right, but nobody builds a single kernel image supporting x86 and arm, so
this doesn't sound impossible to fix.

The code here basically consists of:

- Definition of acpi_irq_model. That can stay here for now.
- Empty stub for acpi_unregister_gsi -- should be in core code
- acpi_gsi_to_irq -- maps directly to irq_find_mapping, core code.
- Code to translate an ACPI interrupt type to a Linux IRQ subsystem type
- Instantiaton of an irq mapping

None of that has anything to do with the arm64 architecture. If we have to
make some small changes to core code to accommodate a non-x86 architecture,
then I think we should at least consider that first.

Will