[RFC PATCH v4 4/5] gpio: gpiolib: Add ngirq member to struct gpio_irq_chip

[Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>]

Supported GPIO IRQs by the chip is not always equal to the number of GPIO
pins. For example on Renesas RZ/G2L SoC where it has GPIO0-122 pins but at
a give point a maximum of only 32 GPIO pins can be used as IRQ lines in
the IRQC domain.

This patch adds ngirq member to struct gpio_irq_chip and passes this as a
size to irq_domain_create_hierarchy()/irq_domain_create_simple() if it is
being set in the driver otherwise fallbacks to using ngpio.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
 drivers/gpio/gpiolib.c      | 4 ++--
 include/linux/gpio/driver.h | 8 ++++++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index aede442f610d..8784d11f8a15 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1221,7 +1221,7 @@ static int gpiochip_hierarchy_add_domain(struct gpio_chip *gc)
 	gc->irq.domain = irq_domain_create_hierarchy(
 		gc->irq.parent_domain,
 		0,
-		gc->ngpio,
+		gc->irq.ngirq ?: gc->ngpio,
 		gc->irq.fwnode,
 		&gc->irq.child_irq_domain_ops,
 		gc);
@@ -1564,7 +1564,7 @@ static int gpiochip_add_irqchip(struct gpio_chip *gc,
 	} else {
 		/* Some drivers provide custom irqdomain ops */
 		gc->irq.domain = irq_domain_create_simple(fwnode,
-			gc->ngpio,
+			gc->irq.ngirq ?: gc->ngpio,
 			gc->irq.first,
 			gc->irq.domain_ops ?: &gpiochip_domain_ops,
 			gc);
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index b0728c8ad90c..eada90d59657 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -51,6 +51,14 @@ struct gpio_irq_chip {
 	 */
 	const struct irq_domain_ops *domain_ops;
 
+	/**
+	 * @ngirq:
+	 *
+	 * The number of GPIO IRQ's handled by this IRQ domain; usually is
+	 * equal to ngpio.
+	 */
+	u16 ngirq;
+
 #ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
 	/**
 	 * @fwnode:
-- 
2.17.1