Re: [PATCH V4 15/23] irqchip/riscv-intc: Add ACPI support

[Sunil V L <sunilvl@ventanamicro.com>]

On Wed, Apr 05, 2023 at 05:48:47PM +0200, Andrew Jones wrote:
> On Tue, Apr 04, 2023 at 11:50:29PM +0530, Sunil V L wrote:
> > Add support for initializing the RISC-V INTC driver on ACPI
> > platforms.
> > 
> > Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> > Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> > Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
> > ---
> >  drivers/irqchip/irq-riscv-intc.c | 74 ++++++++++++++++++++++++++------
> >  1 file changed, 61 insertions(+), 13 deletions(-)
> > 
> > diff --git a/drivers/irqchip/irq-riscv-intc.c b/drivers/irqchip/irq-riscv-intc.c
> > index f229e3e66387..6b476fa356c0 100644
> > --- a/drivers/irqchip/irq-riscv-intc.c
> > +++ b/drivers/irqchip/irq-riscv-intc.c
> > @@ -6,6 +6,7 @@
> >   */
> >  
> >  #define pr_fmt(fmt) "riscv-intc: " fmt
> > +#include <linux/acpi.h>
> >  #include <linux/atomic.h>
> >  #include <linux/bits.h>
> >  #include <linux/cpu.h>
> > @@ -112,6 +113,30 @@ static struct fwnode_handle *riscv_intc_hwnode(void)
> >  	return intc_domain->fwnode;
> >  }
> >  
> > +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);
> > +	if (!intc_domain) {
> > +		pr_err("unable to add IRQ domain\n");
> > +		return -ENXIO;
> > +	}
> > +
> > +	rc = set_handle_irq(&riscv_intc_irq);
> > +	if (rc) {
> > +		pr_err("failed to set irq handler\n");
> > +		return rc;
> > +	}
> > +
> > +	riscv_set_intc_hwnode_fn(riscv_intc_hwnode);
> > +
> > +	pr_info("%d local interrupts mapped\n", BITS_PER_LONG);
> > +
> > +	return 0;
> > +}
> > +
> >  static int __init riscv_intc_init(struct device_node *node,
> >  				  struct device_node *parent)
> >  {
> > @@ -133,24 +158,47 @@ static int __init riscv_intc_init(struct device_node *node,
> >  	if (riscv_hartid_to_cpuid(hartid) != smp_processor_id())
> >  		return 0;
> >  
> > -	intc_domain = irq_domain_add_linear(node, BITS_PER_LONG,
> > -					    &riscv_intc_domain_ops, NULL);
> > -	if (!intc_domain) {
> > -		pr_err("unable to add IRQ domain\n");
> > -		return -ENXIO;
> > -	}
> > -
> > -	rc = set_handle_irq(&riscv_intc_irq);
> > +	rc = riscv_intc_init_common(of_node_to_fwnode(node));
> >  	if (rc) {
> > -		pr_err("failed to set irq handler\n");
> > +		pr_err("failed to initialize INTC\n");
> 
> The ACPI version doesn't output this error when riscv_intc_init_common()
> fails. It should probably be consistent. Either removing it here, if the
> errors output within riscv_intc_init_common() are sufficient, or adding
> it to the ACPI version.
> 
> >  		return rc;
> >  	}
> >  
> > -	riscv_set_intc_hwnode_fn(riscv_intc_hwnode);
> > -
> > -	pr_info("%d local interrupts mapped\n", BITS_PER_LONG);
> > -
> >  	return 0;
> >  }
> >  
> >  IRQCHIP_DECLARE(riscv, "riscv,cpu-intc", riscv_intc_init);
> > +
> > +#ifdef CONFIG_ACPI
> > +
> > +static int __init riscv_intc_acpi_init(union acpi_subtable_headers *header,
> > +				       const unsigned long end)
> > +{
> > +	int rc;
> > +	struct fwnode_handle *fn;
> > +	struct acpi_madt_rintc *rintc;
> > +
> > +	rintc = (struct acpi_madt_rintc *)header;
> > +
> > +	/*
> > +	 * The ACPI MADT will have one INTC for each CPU (or HART)
> > +	 * so riscv_intc_acpi_init() function will be called once
> > +	 * for each INTC. We only do INTC initialization
> > +	 * for the INTC belonging to the boot CPU (or boot HART).
> > +	 */
> > +	if (riscv_hartid_to_cpuid(rintc->hart_id) != smp_processor_id())
> > +		return 0;
> > +
> > +	fn = irq_domain_alloc_named_fwnode("RISCV-INTC");
> > +	if (!fn) {
> > +		pr_err("unable to allocate INTC FW node\n");
> > +		return -ENOMEM;
> > +	}
> > +
> > +	rc = riscv_intc_init_common(fn);
> > +	return rc;
> 
> nit: If we don't add the error message here, then rc can be removed and we
> can just do
> 
>   return riscv_intc_init_common(fn);
> 
> And, if we remove the error above, then we reduce the return there too.
> 
Make sense. Thanks!. Will update in next revision.

Thanks,
Sunil