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Date:   Wed, 5 Apr 2023 17:48:47 +0200
From:   Andrew Jones <ajones@ventanamicro.com>
To:     Sunil V L <sunilvl@ventanamicro.com>
Cc:     linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-riscv@lists.infradead.org, linux-acpi@vger.kernel.org,
        linux-crypto@vger.kernel.org, platform-driver-x86@vger.kernel.org,
        llvm@lists.linux.dev, Jonathan Corbet <corbet@lwn.net>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>, Len Brown <lenb@kernel.org>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Weili Qian <qianweili@huawei.com>,
        Zhou Wang <wangzhou1@hisilicon.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Marc Zyngier <maz@kernel.org>,
        Maximilian Luz <luzmaximilian@gmail.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Mark Gross <markgross@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Tom Rix <trix@redhat.com>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        "David S . Miller" <davem@davemloft.net>,
        "Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
        Conor Dooley <conor.dooley@microchip.com>
Subject: Re: [PATCH V4 15/23] irqchip/riscv-intc: Add ACPI support
Message-ID: <qxftlofleo2bpyqa5lyshiluc5cd37u4hljn4bh7noxv7g5pno@ldvh6gkyrlzu>
References: <20230404182037.863533-1-sunilvl@ventanamicro.com>
 <20230404182037.863533-16-sunilvl@ventanamicro.com>
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In-Reply-To: <20230404182037.863533-16-sunilvl@ventanamicro.com>
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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.

> +}
> +
> +IRQCHIP_ACPI_DECLARE(riscv_intc, ACPI_MADT_TYPE_RINTC, NULL,
> +		     ACPI_MADT_RINTC_VERSION_V1, riscv_intc_acpi_init);
> +#endif
> -- 
> 2.34.1
> 

Thanks,
drew