gpio: mpc8xxx: Make irq_chip immutable

Kernel warns about mutable irq_chips:
"not an immutable chip, please consider fixing!"

Flag the irq_chip as IRQCHIP_IMMUTABLE, add the new helper functions,
and call the appropriate gpiolib functions.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250509-gpio-v1-4-639377c98288@nxp.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Author: MrVan

drivers/gpio/gpio-mpc8xxx.c

@@ -123,9 +123,12 @@ static irqreturn_t mpc8xxx_gpio_irq_cascade(int irq, void *data)
 static void mpc8xxx_irq_unmask(struct irq_data *d)
 {
 	struct mpc8xxx_gpio_chip *mpc8xxx_gc = irq_data_get_irq_chip_data(d);
+	irq_hw_number_t hwirq = irqd_to_hwirq(d);
 	struct gpio_chip *gc = &mpc8xxx_gc->gc;
 	unsigned long flags;
 
+	gpiochip_enable_irq(gc, hwirq);
+
 	raw_spin_lock_irqsave(&mpc8xxx_gc->lock, flags);
 
 	gc->write_reg(mpc8xxx_gc->regs + GPIO_IMR,
@@ -138,6 +141,7 @@ static void mpc8xxx_irq_unmask(struct irq_data *d)
 static void mpc8xxx_irq_mask(struct irq_data *d)
 {
 	struct mpc8xxx_gpio_chip *mpc8xxx_gc = irq_data_get_irq_chip_data(d);
+	irq_hw_number_t hwirq = irqd_to_hwirq(d);
 	struct gpio_chip *gc = &mpc8xxx_gc->gc;
 	unsigned long flags;
 
@@ -148,6 +152,8 @@ static void mpc8xxx_irq_mask(struct irq_data *d)
 		& ~mpc_pin2mask(irqd_to_hwirq(d)));
 
 	raw_spin_unlock_irqrestore(&mpc8xxx_gc->lock, flags);
+
+	gpiochip_disable_irq(gc, hwirq);
 }
 
 static void mpc8xxx_irq_ack(struct irq_data *d)
@@ -244,6 +250,8 @@ static struct irq_chip mpc8xxx_irq_chip = {
 	.irq_ack	= mpc8xxx_irq_ack,
 	/* this might get overwritten in mpc8xxx_probe() */
 	.irq_set_type	= mpc8xxx_irq_set_type,
+	.flags = IRQCHIP_IMMUTABLE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
 };
 
 static int mpc8xxx_gpio_irq_map(struct irq_domain *h, unsigned int irq,