[PATCH v7 02/16] irqchip/riscv-intc: Allow large non-standard interrupt number

[Anup Patel]

On Wed, Jan 10, 2024 at 1:10 PM Yu Chien Peter Lin
<peterlin at 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 at andestech.com>
> Reviewed-by: Randolph <randolph at andestech.com>

Looks good to me.

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

Regards,
Anup

> ---
> Changes v1 -> v2:
>   - Fixed irq mapping failure checking (suggested by Clément and Anup)
> 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_domain_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 = regs->cause & ~CAUSE_IRQ_FLAG;
>
> -       if (unlikely(cause >= 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 <= hwirq && hwirq < riscv_intc_custom_base) ||
> +           (riscv_intc_custom_base + riscv_intc_custom_nr_irqs) <= hwirq)
> +               return -EINVAL;
> +
>         for (i = 0; i < nr_irqs; i++) {
>                 ret = riscv_intc_domain_map(domain, virq + i, hwirq + i);
>                 if (ret)
> @@ -117,8 +127,7 @@ static int __init riscv_intc_init_common(struct fwnode_handle *fn)
>  {
>         int rc;
>
> -       intc_domain = irq_domain_create_linear(fn, BITS_PER_LONG,
> -                                              &riscv_intc_domain_ops, NULL);
> +       intc_domain = 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 fwnode_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 = BITS_PER_LONG;
> +       riscv_intc_custom_base = riscv_intc_nr_irqs;
> +       riscv_intc_custom_nr_irqs = 0;
> +
>         return riscv_intc_init_common(of_node_to_fwnode(node));
>  }
>
> --
> 2.34.1
>