Re: [PATCH v3 2/2] gpio: sch: Hook into ACPI SCI handler to catch GPIO edge events

[Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>]

On Wed, Nov 20, 2019 at 08:20:14PM +0100, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
> 
> The ACPI description on the Quark platform does not provide the required
> information to do establish generic handling. Therefore, we need to hook
> from the driver directly into SCI handler of the ACPI subsystem in order
> to catch and report GPIO-related events.
> 
> Validated on the Quark-based IOT2000 platform.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>

Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>

Below one minor stylistic comment.

> ---
>  drivers/gpio/gpio-sch.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/drivers/gpio/gpio-sch.c b/drivers/gpio/gpio-sch.c
> index 6a9c5500800c..75c95da145d8 100644
> --- a/drivers/gpio/gpio-sch.c
> +++ b/drivers/gpio/gpio-sch.c
> @@ -155,6 +155,31 @@ static const struct gpio_chip sch_gpio_chip = {
>  	.to_irq			= sch_gpio_to_irq,
>  };
>  
> +static u32 sch_sci_handler(void *context)
> +{
> +	struct sch_gpio *sch = context;
> +	unsigned long core_status, resume_status;
> +	unsigned int resume_gpios, offset;
> +
> +	core_status = inl(sch->iobase + GTS);
> +	resume_status = inl(sch->iobase + GTS + 0x20);
> +
> +	if (core_status == 0 && resume_status == 0)

You can also write this like

	if (!core_status &&& !resume_status)

> +		return ACPI_INTERRUPT_NOT_HANDLED;
> +
> +	for_each_set_bit(offset, &core_status, sch->resume_base)
> +		generic_handle_irq(sch->irq_base + offset);
> +
> +	resume_gpios = sch->chip.ngpio - sch->resume_base;
> +	for_each_set_bit(offset, &resume_status, resume_gpios)
> +		generic_handle_irq(sch->irq_base + sch->resume_base + offset);
> +
> +	outl(core_status, sch->iobase + GTS);
> +	outl(resume_status, sch->iobase + GTS + 0x20);
> +
> +	return ACPI_INTERRUPT_HANDLED;
> +}
> +
>  static int sch_irq_type(struct irq_data *d, unsigned int type)
>  {
>  	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(d);
> @@ -215,6 +240,7 @@ static int sch_gpio_probe(struct platform_device *pdev)
>  	struct irq_chip_type *ct;
>  	struct sch_gpio *sch;
>  	struct resource *res;
> +	acpi_status status;
>  	int irq_base, ret;
>  
>  	sch = devm_kzalloc(&pdev->dev, sizeof(*sch), GFP_KERNEL);
> @@ -303,6 +329,10 @@ static int sch_gpio_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> +	status = acpi_install_sci_handler(sch_sci_handler, sch);
> +	if (ACPI_FAILURE(status))
> +		return -EINVAL;
> +
>  	return 0;
>  }
>  
> -- 
> 2.16.4