Re: [PATCH v7 12/17] ARM64 / ACPI: Introduce ACPI_IRQ_MODEL_GIC and register device's gsi

Marc Zyngier
2015-01-16T10:45:59Z

On 14/01/15 15:05, 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.
>
> Originally-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
> Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
> Tested-by: Yijing Wang <wangyijing@huawei.com>
> 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 0b7c3a6..c3e24c4 100644
> --- a/arch/arm64/kernel/acpi.c
> +++ b/arch/arm64/kernel/acpi.c
> @@ -37,6 +37,12 @@ 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.
> */
> @@ -184,6 +190,73 @@ void __init acpi_smp_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);

Is the ACPI implementation really expecting to only deal with a single
domain for interrupts?

This is likely to lead to a number of issues as we're now implementing
stacked domains (GICv2m, GICv3 ITS are already using that model, and
"wire-to MSI translators" will certainly do the same).

This means that, despite having a single GIC described in ACPI, you may
end-up with multiple domains. I expect you'll be safe with MSI (assuming
you never describe them in ACPI), but any form of wire-to-MSI
translation won't work at all.

Thanks,

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