gpio: gpiolib: Allow free() callback to be overridden

Allow free() callback to be overridden from irq_domain_ops for
hierarchical chips.

This allows drivers to free up resources which are allocated during
child_to_parent_hwirq()/populate_parent_alloc_arg() callbacks.

On Renesas RZ/G2L platform a bitmap is maintained for TINT slots, a slot
is allocated in child_to_parent_hwirq() callback which is freed up in free
callback hence this override.
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220707182314.66610-5-prabhakar.mahadev-lad.rj@bp.renesas.com

drivers/gpio/gpiolib.c

@@ -1181,15 +1181,18 @@ static void gpiochip_hierarchy_setup_domain_ops(struct irq_domain_ops *ops)
 	ops->activate = gpiochip_irq_domain_activate;
 	ops->deactivate = gpiochip_irq_domain_deactivate;
 	ops->alloc = gpiochip_hierarchy_irq_domain_alloc;
-	ops->free = irq_domain_free_irqs_common;
 
 	/*
-	 * We only allow overriding the translate() function for
+	 * We only allow overriding the translate() and free() functions for
 	 * hierarchical chips, and this should only be done if the user
-	 * really need something other than 1:1 translation.
+	 * really need something other than 1:1 translation for translate()
+	 * callback and free if user wants to free up any resources which
+	 * were allocated during callbacks, for example populate_parent_alloc_arg.
 	 */
 	if (!ops->translate)
 		ops->translate = gpiochip_hierarchy_irq_domain_translate;
+	if (!ops->free)
+		ops->free = irq_domain_free_irqs_common;
 }
 
 static int gpiochip_hierarchy_add_domain(struct gpio_chip *gc)