Re: [PATCH] ACPI: AGDI: Add interrupt signaling mode support

[Hanjun Guo <guohanjun@huawei.com>]

Hi Kazuhiro,

On 2025/8/18 14:54, 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 singaling mode
> The interrupt vector is retrieved from the AGDI table, and call panic
> function when an interrupt occurs.


> SDEI & Interrupt mode is not supported.

I think this can be removed, it's not allowed naturely.

> 
> Signed-off-by: Kazuhiro Abe <fj1078ii@aa.jp.fujitsu.com>
> ---
>   drivers/acpi/arm64/agdi.c | 114 +++++++++++++++++++++++++++++++++++---
>   include/acpi/actbl2.h     |   4 +-
>   2 files changed, 110 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/acpi/arm64/agdi.c b/drivers/acpi/arm64/agdi.c
> index e0df3daa4abf0..c514bb874c5d3 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;

will we use normal interrupt as the signaling?

In the spec, it says:

Some use-cases, such as system management, require the ability to
generate a non-maskable event to the OS to request the OS kernel to
perform a diagnostic dump and reset the system.

Seems only non-maskable event is allowed, Sudeep, any idea about this?

> +	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 +108,20 @@ static int agdi_probe(struct platform_device *pdev)
>   	if (!adata)
>   		return -EINVAL;
>   
> -	return agdi_sdei_probe(pdev, adata);
> +	switch (adata->flags & ACPI_AGDI_SIGNALING_MODE_MASK) {
> +	case ACPI_AGDI_SIGNALING_MODE_SDEI:
> +		return agdi_sdei_probe(pdev, adata);
> +
> +	case ACPI_AGDI_SIGNALING_MODE_INTERRUPT:
> +		return agdi_interrupt_probe(pdev, adata);
> +	}
> +
> +	return 0;
>   }
>   
> -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 +144,34 @@ 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);
> +
> +	switch (adata->flags & ACPI_AGDI_SIGNALING_MODE_MASK) {
> +	case ACPI_AGDI_SIGNALING_MODE_SDEI:
> +		agdi_sdei_remove(pdev, adata);
> +		break;
> +
> +	case ACPI_AGDI_SIGNALING_MODE_INTERRUPT:
> +		agdi_interrupt_remove(pdev, adata);
> +		break;
> +	}
> +}
> +
>   static struct platform_driver agdi_driver = {
>   	.driver = {
>   		.name = "agdi",
> @@ -94,7 +183,7 @@ 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;
>   
> @@ -103,12 +192,23 @@ void __init acpi_agdi_init(void)
>   	if (ACPI_FAILURE(status))
>   		return;
>   
> -	if (agdi_table->flags & ACPI_AGDI_SIGNALING_MODE) {
> -		pr_warn("Interrupt signaling is not supported");
> +	switch (agdi_table->flags & ACPI_AGDI_SIGNALING_MODE_MASK) {
> +	case ACPI_AGDI_SIGNALING_MODE_SDEI:
> +		pdata.sdei_event = agdi_table->sdei_event;
> +		break;
> +
> +	case ACPI_AGDI_SIGNALING_MODE_INTERRUPT:
> +		pdata.gsiv = agdi_table->gsiv;
> +		break;
> +
> +	default:
> +		pr_warn("Signaling mode(%d) is not supported",
> +			agdi_table->flags & ACPI_AGDI_SIGNALING_MODE_MASK);
>   		goto err_put_table;
>   	}
>   
> -	pdata.sdei_event = agdi_table->sdei_event;
> +	pdata.irq = -1;
> +	pdata.flags = agdi_table->flags;

My major concern is about the normal interrrupt as the event, not sure
if it is ok, let's figure it out first.

>   
>   	pdev = platform_device_register_data(NULL, "agdi", 0, &pdata, sizeof(pdata));
>   	if (IS_ERR(pdev))
> diff --git a/include/acpi/actbl2.h b/include/acpi/actbl2.h
> index 048f5f47f8b88..9ddbdd772f139 100644
> --- a/include/acpi/actbl2.h
> +++ b/include/acpi/actbl2.h
> @@ -339,7 +339,9 @@ struct acpi_table_agdi {
>   
>   /* Mask for Flags field above */
>   
> -#define ACPI_AGDI_SIGNALING_MODE (1)
> +#define ACPI_AGDI_SIGNALING_MODE_MASK (3)
> +#define ACPI_AGDI_SIGNALING_MODE_SDEI (0)
> +#define ACPI_AGDI_SIGNALING_MODE_INTERRUPT (1)

You need to send a patch to ACPICA first to add interrupt support,
this file belongs acpica.

Thanks
Hanjun