gpio: mt7621: Make the irqchip immutable

Commit 6c846d02 ("gpio: Don't fiddle with irqchips marked as
immutable") added a warning to indicate if the gpiolib is altering the
internals of irqchips.  Following this change the following warnings
are now observed for the mt7621 driver:

gpio gpiochip0: (1e000600.gpio-bank0): not an immutable chip, please consider fixing it!
gpio gpiochip1: (1e000600.gpio-bank1): not an immutable chip, please consider fixing it!
gpio gpiochip2: (1e000600.gpio-bank2): not an immutable chip, please consider fixing it!

Fix this by making the irqchip in the mt7621 driver immutable.
Tested-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

drivers/gpio/gpio-mt7621.c

@@ -112,6 +112,8 @@ mediatek_gpio_irq_unmask(struct irq_data *d)
 	unsigned long flags;
 	u32 rise, fall, high, low;
 
+	gpiochip_enable_irq(gc, d->hwirq);
+
 	spin_lock_irqsave(&rg->lock, flags);
 	rise = mtk_gpio_r32(rg, GPIO_REG_REDGE);
 	fall = mtk_gpio_r32(rg, GPIO_REG_FEDGE);
@@ -143,6 +145,8 @@ mediatek_gpio_irq_mask(struct irq_data *d)
 	mtk_gpio_w32(rg, GPIO_REG_HLVL, high & ~BIT(pin));
 	mtk_gpio_w32(rg, GPIO_REG_LLVL, low & ~BIT(pin));
 	spin_unlock_irqrestore(&rg->lock, flags);
+
+	gpiochip_disable_irq(gc, d->hwirq);
 }
 
 static int
@@ -204,6 +208,16 @@ mediatek_gpio_xlate(struct gpio_chip *chip,
 	return gpio % MTK_BANK_WIDTH;
 }
 
+static const struct irq_chip mt7621_irq_chip = {
+	.name		= "mt7621-gpio",
+	.irq_mask_ack	= mediatek_gpio_irq_mask,
+	.irq_mask	= mediatek_gpio_irq_mask,
+	.irq_unmask	= mediatek_gpio_irq_unmask,
+	.irq_set_type	= mediatek_gpio_irq_type,
+	.flags		= IRQCHIP_IMMUTABLE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
+};
+
 static int
 mediatek_gpio_bank_probe(struct device *dev, int bank)
 {
@@ -238,11 +252,6 @@ mediatek_gpio_bank_probe(struct device *dev, int bank)
 		return -ENOMEM;
 
 	rg->chip.offset = bank * MTK_BANK_WIDTH;
-	rg->irq_chip.name = dev_name(dev);
-	rg->irq_chip.irq_unmask = mediatek_gpio_irq_unmask;
-	rg->irq_chip.irq_mask = mediatek_gpio_irq_mask;
-	rg->irq_chip.irq_mask_ack = mediatek_gpio_irq_mask;
-	rg->irq_chip.irq_set_type = mediatek_gpio_irq_type;
 
 	if (mtk->gpio_irq) {
 		struct gpio_irq_chip *girq;
@@ -262,7 +271,7 @@ mediatek_gpio_bank_probe(struct device *dev, int bank)
 		}
 
 		girq = &rg->chip.irq;
-		girq->chip = &rg->irq_chip;
+		gpio_irq_chip_set_chip(girq, &mt7621_irq_chip);
 		/* This will let us handle the parent IRQ in the driver */
 		girq->parent_handler = NULL;
 		girq->num_parents = 0;