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

From: Jan Kiszka <jan.kiszka@siemens.com>

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@siemens.com>
---
 drivers/gpio/gpio-sch.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

On Wed, Nov 20, 2019 at 08:20:14PM +0100, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> 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@siemens.com>

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>

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