gpio: timberdale: Make irq_chip immutable

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

Constify timbgpio_irqchip, 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-v1-8-639377c98288@nxp.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Author: MrVan

drivers/gpio/gpio-timberdale.c

@@ -103,20 +103,26 @@ static void timbgpio_irq_disable(struct irq_data *d)
 {
 	struct timbgpio *tgpio = irq_data_get_irq_chip_data(d);
 	int offset = d->irq - tgpio->irq_base;
+	irq_hw_number_t hwirq = irqd_to_hwirq(d);
 	unsigned long flags;
 
 	spin_lock_irqsave(&tgpio->lock, flags);
 	tgpio->last_ier &= ~(1UL << offset);
 	iowrite32(tgpio->last_ier, tgpio->membase + TGPIO_IER);
 	spin_unlock_irqrestore(&tgpio->lock, flags);
+
+	gpiochip_disable_irq(&tgpio->gpio, hwirq);
 }
 
 static void timbgpio_irq_enable(struct irq_data *d)
 {
 	struct timbgpio *tgpio = irq_data_get_irq_chip_data(d);
 	int offset = d->irq - tgpio->irq_base;
+	irq_hw_number_t hwirq = irqd_to_hwirq(d);
 	unsigned long flags;
 
+	gpiochip_enable_irq(&tgpio->gpio, hwirq);
+
 	spin_lock_irqsave(&tgpio->lock, flags);
 	tgpio->last_ier |= 1UL << offset;
 	iowrite32(tgpio->last_ier, tgpio->membase + TGPIO_IER);
@@ -205,11 +211,13 @@ static void timbgpio_irq(struct irq_desc *desc)
 	iowrite32(tgpio->last_ier, tgpio->membase + TGPIO_IER);
 }
 
-static struct irq_chip timbgpio_irqchip = {
+static const struct irq_chip timbgpio_irqchip = {
 	.name		= "GPIO",
 	.irq_enable	= timbgpio_irq_enable,
 	.irq_disable	= timbgpio_irq_disable,
 	.irq_set_type	= timbgpio_irq_type,
+	.flags = IRQCHIP_IMMUTABLE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
 };
 
 static int timbgpio_probe(struct platform_device *pdev)