pinctrl: starfive: Make the irqchip immutable

Commit 6c846d0 ("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 warning is
now observed for the starfive driver:

    gpio gpiochip0: (11910000.pinctrl): not an immutable chip, please consider fixing it!

Fix this by making the irqchip in the starfive driver immutable.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/5eb66be34356afd5eb0ea9027329e0939d03d3a0.1652884852.git.geert+renesas@glider.be
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Author: geertu

drivers/pinctrl/pinctrl-starfive.c

@@ -1074,6 +1074,8 @@ static void starfive_irq_mask(struct irq_data *d)
 	value = readl_relaxed(ie) & ~mask;
 	writel_relaxed(value, ie);
 	raw_spin_unlock_irqrestore(&sfp->lock, flags);
+
+	gpiochip_disable_irq(&sfp->gc, d->hwirq);
 }
 
 static void starfive_irq_mask_ack(struct irq_data *d)
@@ -1102,6 +1104,8 @@ static void starfive_irq_unmask(struct irq_data *d)
 	unsigned long flags;
 	u32 value;
 
+	gpiochip_enable_irq(&sfp->gc, d->hwirq);
+
 	raw_spin_lock_irqsave(&sfp->lock, flags);
 	value = readl_relaxed(ie) | mask;
 	writel_relaxed(value, ie);
@@ -1163,14 +1167,15 @@ static int starfive_irq_set_type(struct irq_data *d, unsigned int trigger)
 	return 0;
 }
 
-static struct irq_chip starfive_irq_chip = {
+static const struct irq_chip starfive_irq_chip = {
 	.name = "StarFive GPIO",
 	.irq_ack = starfive_irq_ack,
 	.irq_mask = starfive_irq_mask,
 	.irq_mask_ack = starfive_irq_mask_ack,
 	.irq_unmask = starfive_irq_unmask,
 	.irq_set_type = starfive_irq_set_type,
-	.flags = IRQCHIP_SET_TYPE_MASKED,
+	.flags = IRQCHIP_IMMUTABLE | IRQCHIP_SET_TYPE_MASKED,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
 };
 
 static void starfive_gpio_irq_handler(struct irq_desc *desc)
@@ -1308,7 +1313,7 @@ static int starfive_probe(struct platform_device *pdev)
 	sfp->gc.base = -1;
 	sfp->gc.ngpio = NR_GPIOS;
 
-	sfp->gc.irq.chip = &starfive_irq_chip;
+	gpio_irq_chip_set_chip(&sfp->gc.irq, &starfive_irq_chip);
 	sfp->gc.irq.parent_handler = starfive_gpio_irq_handler;
 	sfp->gc.irq.num_parents = 1;
 	sfp->gc.irq.parents = devm_kcalloc(dev, sfp->gc.irq.num_parents,