gpio: rda: Convert to immutable irq_chip

Convert the driver to immutable irq-chip with a bit of
intuition.

Cc: Marc Zyngier <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>
Acked-by: Manivannan Sadhasivam <[e-mail]>
Reviewed-by: Marc Zyngier <[e-mail]>
Signed-off-by: Bartosz Golaszewski <[e-mail]>

drivers/gpio/gpio-rda.c

···
 	struct gpio_chip chip;
 	void __iomem *base;
 	spinlock_t lock;
-	struct irq_chip irq_chip;
 	int irq;
 };
 
···
 	value |= BIT(offset) << RDA_GPIO_IRQ_FALL_SHIFT;
 
 	writel_relaxed(value, base + RDA_GPIO_INT_CTRL_CLR);
+	gpiochip_disable_irq(chip, offset);
 }
 
 static void rda_gpio_irq_ack(struct irq_data *data)
···
 	u32 offset = irqd_to_hwirq(data);
 	u32 trigger = irqd_get_trigger_type(data);
 
+	gpiochip_enable_irq(chip, offset);
 	rda_gpio_set_irq(chip, offset, trigger);
 }
 
···
 
 	chained_irq_exit(ic, desc);
 }
+
+static const struct irq_chip rda_gpio_irq_chip = {
+	.name = "rda-gpio",
+	.irq_ack = rda_gpio_irq_ack,
+	.irq_mask = rda_gpio_irq_mask,
+	.irq_unmask = rda_gpio_irq_unmask,
+	.irq_set_type = rda_gpio_irq_set_type,
+	.flags = IRQCHIP_SKIP_SET_WAKE | IRQCHIP_IMMUTABLE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
+};
 
 static int rda_gpio_probe(struct platform_device *pdev)
 {
···
 	rda_gpio->chip.base = -1;
 
 	if (rda_gpio->irq >= 0) {
-		rda_gpio->irq_chip.name = "rda-gpio",
-		rda_gpio->irq_chip.irq_ack = rda_gpio_irq_ack,
-		rda_gpio->irq_chip.irq_mask = rda_gpio_irq_mask,
-		rda_gpio->irq_chip.irq_unmask = rda_gpio_irq_unmask,
-		rda_gpio->irq_chip.irq_set_type = rda_gpio_irq_set_type,
-		rda_gpio->irq_chip.flags = IRQCHIP_SKIP_SET_WAKE,
-
 		girq = &rda_gpio->chip.irq;
-		girq->chip = &rda_gpio->irq_chip;
+		gpio_irq_chip_set_chip(girq, &rda_gpio_irq_chip);
 		girq->handler = handle_bad_irq;
 		girq->default_type = IRQ_TYPE_NONE;
 		girq->parent_handler = rda_gpio_irq_handler;