Message-ID: <bd45c06a-77cc-2ab3-122e-41dee1aee0ac@os.amperecomputing.com>
Date: Mon, 8 Sep 2025 12:02:14 -0700 (PDT)
From: Ilkka Koskinen <ilkka@...amperecomputing.com>
To: Kazuhiro Abe <fj1078ii@...jp.fujitsu.com>
cc: Lorenzo Pieralisi <lpieralisi@...nel.org>, 
    Hanjun Guo <guohanjun@...wei.com>, Sudeep Holla <sudeep.holla@....com>, 
    "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>, 
    linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
    linux-kernel@...r.kernel.org, 
    Ilkka Koskinen <ilkka@...amperecomputing.com>
Subject: Re: [PATCH v3] ACPI: AGDI: Add interrupt signaling mode support


Hi Kazuhiro,

On Fri, 5 Sep 2025, Kazuhiro Abe wrote:
> AGDI has two types of signaling modes: SDEI and interrupt.
> Currently, the AGDI driver only supports SDEI.
> Therefore, add support for interrupt signaling mode
> The interrupt vector is retrieved from the AGDI table, and call panic
> function when an interrupt occurs.
>
> Signed-off-by: Kazuhiro Abe <fj1078ii@...jp.fujitsu.com>


Looks good to me.

Reviewed-by: Ilkka Koskinen <ilkka@...amperecomputing.com>


Hanjun & Sudeep, what's your thought on enabling the use of regular
interrupts here? I do agree the spec talks about non-maskable ones and
to my understanding that's what the idea was indeed.

Cheers, Ilkka


> ---
> I keep normal IRQ code when NMI cannot be used.
> If there is any concern, please let me know.
>
> v2->v3
> - Fix bug in the return value of agdi_probe function.
> - Remove unnecessary curly braces in the agdi_remove function.
>
> v2: https://lore.kernel.org/all/20250829101154.2377800-1-fj1078ii@aa.jp.fujitsu.com/
> v1->v2
> - Remove acpica update since there is no need to update define value
>   for this patch.
> ---
> drivers/acpi/arm64/agdi.c | 95 ++++++++++++++++++++++++++++++++++++---
> 1 file changed, 88 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/acpi/arm64/agdi.c b/drivers/acpi/arm64/agdi.c
> index e0df3daa4abf..2313a46f01cd 100644
> --- a/drivers/acpi/arm64/agdi.c
> +++ b/drivers/acpi/arm64/agdi.c
> @@ -16,7 +16,11 @@
> #include "init.h"
>
> struct agdi_data {
> +	unsigned char flags;
> 	int sdei_event;
> +	unsigned int gsiv;
> +	bool use_nmi;
> +	int irq;
> };
>
> static int agdi_sdei_handler(u32 sdei_event, struct pt_regs *regs, void *arg)
> @@ -48,6 +52,55 @@ static int agdi_sdei_probe(struct platform_device *pdev,
> 	return 0;
> }
>
> +static irqreturn_t agdi_interrupt_handler_nmi(int irq, void *dev_id)
> +{
> +	nmi_panic(NULL, "Arm Generic Diagnostic Dump and Reset NMI Interrupt event issued\n");
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t agdi_interrupt_handler_irq(int irq, void *dev_id)
> +{
> +	panic("Arm Generic Diagnostic Dump and Reset Interrupt event issued\n");
> +	return IRQ_HANDLED;
> +}
> +
> +static int agdi_interrupt_probe(struct platform_device *pdev,
> +				struct agdi_data *adata)
> +{
> +	unsigned long irq_flags;
> +	int ret;
> +	int irq;
> +
> +	irq = acpi_register_gsi(NULL, adata->gsiv, ACPI_EDGE_SENSITIVE, ACPI_ACTIVE_HIGH);
> +	if (irq < 0) {
> +		dev_err(&pdev->dev, "cannot register GSI#%d (%d)\n", adata->gsiv, irq);
> +		return irq;
> +	}
> +
> +	irq_flags = IRQF_PERCPU | IRQF_NOBALANCING | IRQF_NO_AUTOEN |
> +		    IRQF_NO_THREAD;
> +	/* try NMI first */
> +	ret = request_nmi(irq, &agdi_interrupt_handler_nmi, irq_flags,
> +			  "agdi_interrupt_nmi", NULL);
> +	if (ret) {
> +		ret = request_irq(irq, &agdi_interrupt_handler_irq,
> +				  irq_flags, "agdi_interrupt_irq", NULL);
> +		if (ret) {
> +			dev_err(&pdev->dev, "cannot register IRQ %d\n", ret);
> +			acpi_unregister_gsi(adata->gsiv);
> +			return ret;
> +		}
> +		enable_irq(irq);
> +		adata->irq = irq;
> +	} else {
> +		enable_nmi(irq);
> +		adata->irq = irq;
> +		adata->use_nmi = true;
> +	}
> +
> +	return 0;
> +}
> +
> static int agdi_probe(struct platform_device *pdev)
> {
> 	struct agdi_data *adata = dev_get_platdata(&pdev->dev);
> @@ -55,12 +108,15 @@ static int agdi_probe(struct platform_device *pdev)
> 	if (!adata)
> 		return -EINVAL;
>
> -	return agdi_sdei_probe(pdev, adata);
> +	if (adata->flags & ACPI_AGDI_SIGNALING_MODE)
> +		return agdi_interrupt_probe(pdev, adata);
> +	else
> +		return agdi_sdei_probe(pdev, adata);
> }
>
> -static void agdi_remove(struct platform_device *pdev)
> +static void agdi_sdei_remove(struct platform_device *pdev,
> +			     struct agdi_data *adata)
> {
> -	struct agdi_data *adata = dev_get_platdata(&pdev->dev);
> 	int err, i;
>
> 	err = sdei_event_disable(adata->sdei_event);
> @@ -83,6 +139,29 @@ static void agdi_remove(struct platform_device *pdev)
> 			adata->sdei_event, ERR_PTR(err));
> }
>
> +static void agdi_interrupt_remove(struct platform_device *pdev,
> +				  struct agdi_data *adata)
> +{
> +	if (adata->irq != -1) {
> +		if (adata->use_nmi)
> +			free_nmi(adata->irq, NULL);
> +		else
> +			free_irq(adata->irq, NULL);
> +
> +		acpi_unregister_gsi(adata->gsiv);
> +	}
> +}
> +
> +static void agdi_remove(struct platform_device *pdev)
> +{
> +	struct agdi_data *adata = dev_get_platdata(&pdev->dev);
> +
> +	if (adata->flags & ACPI_AGDI_SIGNALING_MODE)
> +		agdi_interrupt_remove(pdev, adata);
> +	else
> +		agdi_sdei_remove(pdev, adata);
> +}
> +
> static struct platform_driver agdi_driver = {
> 	.driver = {
> 		.name = "agdi",
> @@ -94,7 +173,7 @@ static struct platform_driver agdi_driver = {
> void __init acpi_agdi_init(void)
> {
> 	struct acpi_table_agdi *agdi_table;
> -	struct agdi_data pdata;
> +	struct agdi_data pdata = {0};
> 	struct platform_device *pdev;
> 	acpi_status status;
>
> @@ -104,11 +183,13 @@ void __init acpi_agdi_init(void)
> 		return;
>
> 	if (agdi_table->flags & ACPI_AGDI_SIGNALING_MODE) {
> -		pr_warn("Interrupt signaling is not supported");
> -		goto err_put_table;
> +		pdata.gsiv = agdi_table->gsiv;
> +	} else {
> +		pdata.sdei_event = agdi_table->sdei_event;
> 	}
>
> -	pdata.sdei_event = agdi_table->sdei_event;
> +	pdata.irq = -1;
> +	pdata.flags = agdi_table->flags;
>
> 	pdev = platform_device_register_data(NULL, "agdi", 0, &pdata, sizeof(pdata));
> 	if (IS_ERR(pdev))
> -- 
> 2.43.0
>
>

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