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

[Atish Patra]

On Wed, Jan 10, 2024 at 7:11 AM Anup Patel <anup@xxxxxxxxxxxxxx> wrote:
>
> On Wed, Jan 10, 2024 at 1:10 PM Yu Chien Peter Lin
> <peterlin@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx>
> > Reviewed-by: Randolph <randolph@xxxxxxxxxxxxx>
>
> Looks good to me.
>
> Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxx/#25573085
> > [2] https://patchwork.kernel.org/project/linux-riscv/patch/20231213070301.1684751-3-peterlin@xxxxxxxxxxxxx/#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
> >


Reviewed-by: Atish Patra <atishp@xxxxxxxxxxxx>

-- 
Regards,
Atish