Messages in this thread | | | From | Anup Patel <> | Date | Wed, 26 Jan 2022 15:42:25 +0530 | Subject | Re: [PATCH 2/6] irqchip/riscv-intc: Set intc domain as the default host |
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On Wed, Jan 26, 2022 at 2:31 PM Marc Zyngier <maz@kernel.org> wrote: > > On Wed, 26 Jan 2022 03:16:55 +0000, > Anup Patel <anup@brainfault.org> wrote: > > > > On Tue, Jan 25, 2022 at 11:47 PM Marc Zyngier <maz@kernel.org> wrote: > > > > > > On Tue, 25 Jan 2022 05:42:13 +0000, > > > Anup Patel <apatel@ventanamicro.com> wrote: > > > > > > > > We have quite a few RISC-V drivers (such as RISC-V SBI IPI driver, > > > > RISC-V timer driver, RISC-V PMU driver, etc) which do not have a > > > > dedicated DT/ACPI fwnode. This patch makes intc domain as the default > > > > host so that these drivers can directly create local interrupt mapping > > > > using standardized local interrupt numbers > > > > > > > > Signed-off-by: Anup Patel <apatel@ventanamicro.com> > > > > --- > > > > drivers/clocksource/timer-riscv.c | 17 +---------------- > > > > drivers/irqchip/irq-riscv-intc.c | 9 +++++++++ > > > > 2 files changed, 10 insertions(+), 16 deletions(-) > > > > > > > > diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c > > > > index 1767f8bf2013..dd6916ae6365 100644 > > > > --- a/drivers/clocksource/timer-riscv.c > > > > +++ b/drivers/clocksource/timer-riscv.c > > > > @@ -102,8 +102,6 @@ static irqreturn_t riscv_timer_interrupt(int irq, void *dev_id) > > > > static int __init riscv_timer_init_dt(struct device_node *n) > > > > { > > > > int cpuid, hartid, error; > > > > - struct device_node *child; > > > > - struct irq_domain *domain; > > > > > > > > hartid = riscv_of_processor_hartid(n); > > > > if (hartid < 0) { > > > > @@ -121,20 +119,7 @@ static int __init riscv_timer_init_dt(struct device_node *n) > > > > if (cpuid != smp_processor_id()) > > > > return 0; > > > > > > > > - domain = NULL; > > > > - child = of_get_compatible_child(n, "riscv,cpu-intc"); > > > > - if (!child) { > > > > - pr_err("Failed to find INTC node [%pOF]\n", n); > > > > - return -ENODEV; > > > > - } > > > > - domain = irq_find_host(child); > > > > - of_node_put(child); > > > > - if (!domain) { > > > > - pr_err("Failed to find IRQ domain for node [%pOF]\n", n); > > > > - return -ENODEV; > > > > - } > > > > - > > > > - riscv_clock_event_irq = irq_create_mapping(domain, RV_IRQ_TIMER); > > > > + riscv_clock_event_irq = irq_create_mapping(NULL, RV_IRQ_TIMER); > > > > if (!riscv_clock_event_irq) { > > > > pr_err("Failed to map timer interrupt for node [%pOF]\n", n); > > > > return -ENODEV; > > > > diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c > > > > index b65bd8878d4f..9f0a7a8a5c4d 100644 > > > > --- a/drivers/irqchip/irq-riscv-intc.c > > > > +++ b/drivers/irqchip/irq-riscv-intc.c > > > > @@ -125,6 +125,15 @@ static int __init riscv_intc_init(struct device_node *node, > > > > return rc; > > > > } > > > > > > > > + /* > > > > + * Make INTC as the default domain which will allow drivers > > > > + * not having dedicated DT/ACPI fwnode (such as RISC-V SBI IPI > > > > + * driver, RISC-V timer driver, RISC-V PMU driver, etc) can > > > > + * directly create local interrupt mapping using standardized > > > > + * local interrupt numbers. > > > > + */ > > > > + irq_set_default_host(intc_domain); > > > > > > No, please. This really is a bad idea. This sort of catch-all have > > > constantly proven to be a nuisance, because they discard all the > > > topology information. Eventually, you realise that you need to know > > > where this is coming from, but it really is too late. > > > > > > I'd rather you *synthesise* a fwnode (like ACPI does) rather then do > > > this. > > > > In absence of INTC as the default domain, currently we have various > > drivers looking up INTC irq_domain from DT (or ACPI). This is quite a > > bit of duplicate code across various drivers. > > > > How about having a irq_domain lookup routine (riscv_intc_find_irq_domain()) > > exported by the RISC-V INTC driver or arch/riscv ? > > OR > > Do you have an alternative suggestion ? > > But *why* don't you provide an interrupt controller node for DT? I > really don't think that's outlandish to require.
Historically, all RISC-V SBI related drivers never had any DT/ACPI node because we can always query/discover the SBI functionality at runtime.
The mechanism to query/discover SBI IPI, Timer and PMU is through SBI base functions. Also, local interrupts used by these drivers are specified by the RISC-V specification. This means having a DT/ACPI node for these drivers doesn't provide any info.
We will be having KVM RISC-V AIA support in future which will not have a DT/ACPI node as well because this can be discovered as a CPU capability and the local interrupt to be used is specified by the RISC-V hypervisor specification.
> > For ACPI, we already have an interface that allows a fwnode to be > registered (acpi_set_irq_model) and interrupts mapped > (acpi_register_gsi).
The ACPI specification being proposed for RISC-V does not have any details for SBI IPI, Timer, and PMU for the same reasons mentioned above.
> > You should already have all the required tools you need.
Are you okay if arch/riscv exports riscv_intc_find_irq_domain() ? OR Maybe export riscv_intc_find_irq_domain() from INTC driver ?
Regards, Anup
> > M. > > -- > Without deviation from the norm, progress is not possible.
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