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From: Anup Patel <anup@brainfault.org>
Date: Wed, 10 Jan 2024 20:41:16 +0530
Message-ID: <CAAhSdy1KLSFBA_vD+NX15wuiOsz5QadQWj4ZWOK11qfL1LuHqA@mail.gmail.com>
Subject: Re: [PATCH v7 02/16] irqchip/riscv-intc: Allow large non-standard
 interrupt number
To: Yu Chien Peter Lin <peterlin@andestech.com>
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On Wed, Jan 10, 2024 at 1:10=E2=80=AFPM Yu Chien Peter Lin
<peterlin@andestech.com> wrote:
>
> Currently, the implementation of the RISC-V INTC driver uses the
> interrupt cause as the hardware interrupt number, with a maximum of
> 64 interrupts. However, the platform can expand the interrupt number
> further for custom local interrupts.
>
> To fully utilize the available local interrupt sources, switch
> to using irq_domain_create_tree() that creates the radix tree
> map, add global variables (riscv_intc_nr_irqs, riscv_intc_custom_base
> and riscv_intc_custom_nr_irqs) to determine the valid range of local
> interrupt number (hwirq).
>
> Signed-off-by: Yu Chien Peter Lin <peterlin@andestech.com>
> Reviewed-by: Randolph <randolph@andestech.com>

Looks good to me.

Reviewed-by: Anup Patel <anup@brainfault.org>

Regards,
Anup

> ---
> Changes v1 -> v2:
>   - Fixed irq mapping failure checking (suggested by Cl=C3=A9ment and Anu=
p)
> Changes v2 -> v3:
>   - No change
> Changes v3 -> v4: (Suggested by Thomas [1])
>   - Use pr_warn_ratelimited instead
>   - Fix coding style and commit message
> Changes v4 -> v5: (Suggested by Thomas)
>   - Fix commit message
> Changes v5 -> v6: (Suggested by Anup [2])
>   - Add riscv_intc_* global variables for checking range in riscv_intc_do=
main_alloc()
>   - Advertise the number of interrupts allowed
> Changes v6 -> v7:
>   - No functional change
>
> [1] https://patchwork.kernel.org/project/linux-riscv/patch/20231023004100=
2663486-3-peterlin@andestech.com/#25573085
> [2] https://patchwork.kernel.org/project/linux-riscv/patch/20231213070301=
1684751-3-peterlin@andestech.com/#25636589
> ---
>  drivers/irqchip/irq-riscv-intc.c | 30 +++++++++++++++++++++++-------
>  1 file changed, 23 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv=
-intc.c
> index e8d01b14ccdd..b13a16b164c9 100644
> --- a/drivers/irqchip/irq-riscv-intc.c
> +++ b/drivers/irqchip/irq-riscv-intc.c
> @@ -19,15 +19,17 @@
>  #include <linux/smp.h>
>
>  static struct irq_domain *intc_domain;
> +static unsigned int riscv_intc_nr_irqs __ro_after_init;
> +static unsigned int riscv_intc_custom_base __ro_after_init;
> +static unsigned int riscv_intc_custom_nr_irqs __ro_after_init;
>
>  static asmlinkage void riscv_intc_irq(struct pt_regs *regs)
>  {
>         unsigned long cause =3D regs->cause & ~CAUSE_IRQ_FLAG;
>
> -       if (unlikely(cause >=3D BITS_PER_LONG))
> -               panic("unexpected interrupt cause");
> -
> -       generic_handle_domain_irq(intc_domain, cause);
> +       if (generic_handle_domain_irq(intc_domain, cause))
> +               pr_warn_ratelimited("Failed to handle interrupt (cause: %=
ld)\n",
> +                                   cause);
>  }
>
>  /*
> @@ -93,6 +95,14 @@ static int riscv_intc_domain_alloc(struct irq_domain *=
domain,
>         if (ret)
>                 return ret;
>
> +       /*
> +        * Only allow hwirq for which we have corresponding standard or
> +        * custom interrupt enable register.
> +        */
> +       if ((riscv_intc_nr_irqs <=3D hwirq && hwirq < riscv_intc_custom_b=
ase) ||
> +           (riscv_intc_custom_base + riscv_intc_custom_nr_irqs) <=3D hwi=
rq)
> +               return -EINVAL;
> +
>         for (i =3D 0; i < nr_irqs; i++) {
>                 ret =3D riscv_intc_domain_map(domain, virq + i, hwirq + i=
);
>                 if (ret)
> @@ -117,8 +127,7 @@ static int __init riscv_intc_init_common(struct fwnod=
e_handle *fn)
>  {
>         int rc;
>
> -       intc_domain =3D irq_domain_create_linear(fn, BITS_PER_LONG,
> -                                              &riscv_intc_domain_ops, NU=
LL);
> +       intc_domain =3D irq_domain_create_tree(fn, &riscv_intc_domain_ops=
, NULL);
>         if (!intc_domain) {
>                 pr_err("unable to add IRQ domain\n");
>                 return -ENXIO;
> @@ -132,7 +141,10 @@ static int __init riscv_intc_init_common(struct fwno=
de_handle *fn)
>
>         riscv_set_intc_hwnode_fn(riscv_intc_hwnode);
>
> -       pr_info("%d local interrupts mapped\n", BITS_PER_LONG);
> +       pr_info("%d local interrupts mapped\n", riscv_intc_nr_irqs);
> +       if (riscv_intc_custom_nr_irqs)
> +               pr_info("%d custom local interrupts mapped\n",
> +                       riscv_intc_custom_nr_irqs);
>
>         return 0;
>  }
> @@ -166,6 +178,10 @@ static int __init riscv_intc_init(struct device_node=
 *node,
>                 return 0;
>         }
>
> +       riscv_intc_nr_irqs =3D BITS_PER_LONG;
> +       riscv_intc_custom_base =3D riscv_intc_nr_irqs;
> +       riscv_intc_custom_nr_irqs =3D 0;
> +
>         return riscv_intc_init_common(of_node_to_fwnode(node));
>  }
>
> --
> 2.34.1
>