gpio: 104-idio-16: Use irqchip template

This makes the driver use the irqchip template to assign
properties to the gpio_irq_chip instead of using the
explicit call to gpiochip_irqchip_add().

The irqchip is instead added while adding the gpiochip.
Also move the IRQ initialization to the special .init_hw()
callback.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Cc: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/20200722105517.186137-1-linus.walleij@linaro.org

drivers/gpio/gpio-104-idio-16.c

@@ -224,10 +224,22 @@ static const char *idio_16_names[IDIO_16_NGPIO] = {
 	"IIN8", "IIN9", "IIN10", "IIN11", "IIN12", "IIN13", "IIN14", "IIN15"
 };
 
+static int idio_16_irq_init_hw(struct gpio_chip *gc)
+{
+	struct idio_16_gpio *const idio16gpio = gpiochip_get_data(gc);
+
+	/* Disable IRQ by default */
+	outb(0, idio16gpio->base + 2);
+	outb(0, idio16gpio->base + 1);
+
+	return 0;
+}
+
 static int idio_16_probe(struct device *dev, unsigned int id)
 {
 	struct idio_16_gpio *idio16gpio;
 	const char *const name = dev_name(dev);
+	struct gpio_irq_chip *girq;
 	int err;
 
 	idio16gpio = devm_kzalloc(dev, sizeof(*idio16gpio), GFP_KERNEL);
@@ -256,6 +268,16 @@ static int idio_16_probe(struct device *dev, unsigned int id)
 	idio16gpio->base = base[id];
 	idio16gpio->out_state = 0xFFFF;
 
+	girq = &idio16gpio->chip.irq;
+	girq->chip = &idio_16_irqchip;
+	/* This will let us handle the parent IRQ in the driver */
+	girq->parent_handler = NULL;
+	girq->num_parents = 0;
+	girq->parents = NULL;
+	girq->default_type = IRQ_TYPE_NONE;
+	girq->handler = handle_edge_irq;
+	girq->init_hw = idio_16_irq_init_hw;
+
 	raw_spin_lock_init(&idio16gpio->lock);
 
 	err = devm_gpiochip_add_data(dev, &idio16gpio->chip, idio16gpio);
@@ -264,17 +286,6 @@ static int idio_16_probe(struct device *dev, unsigned int id)
 		return err;
 	}
 
-	/* Disable IRQ by default */
-	outb(0, base[id] + 2);
-	outb(0, base[id] + 1);
-
-	err = gpiochip_irqchip_add(&idio16gpio->chip, &idio_16_irqchip, 0,
-		handle_edge_irq, IRQ_TYPE_NONE);
-	if (err) {
-		dev_err(dev, "Could not add irqchip (%d)\n", err);
-		return err;
-	}
-
 	err = devm_request_irq(dev, irq[id], idio_16_irq_handler, 0, name,
 		idio16gpio);
 	if (err) {