irqchip/mmp: Add missing chained_irq_{enter,exit}()

The lack of chained_irq_exit() leaves the muxed interrupt masked on MMP3.
For reasons unknown this is not a problem on MMP2.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20190822092643.593488-8-lkundrak@v3.sk

drivers/irqchip/irq-mmp.c

@@ -13,6 +13,7 @@
 #include <linux/init.h>
 #include <linux/irq.h>
 #include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
 #include <linux/irqdomain.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
@@ -132,11 +133,14 @@ struct irq_chip icu_irq_chip = {
 static void icu_mux_irq_demux(struct irq_desc *desc)
 {
 	unsigned int irq = irq_desc_get_irq(desc);
+	struct irq_chip *chip = irq_desc_get_chip(desc);
 	struct irq_domain *domain;
 	struct icu_chip_data *data;
 	int i;
 	unsigned long mask, status, n;
 
+	chained_irq_enter(chip, desc);
+
 	for (i = 1; i < max_icu_nr; i++) {
 		if (irq == icu_data[i].cascade_irq) {
 			domain = icu_data[i].domain;
@@ -146,7 +150,7 @@ static void icu_mux_irq_demux(struct irq_desc *desc)
 	}
 	if (i >= max_icu_nr) {
 		pr_err("Spurious irq %d in MMP INTC\n", irq);
-		return;
+		goto out;
 	}
 
 	mask = readl_relaxed(data->reg_mask);
@@ -158,6 +162,9 @@ static void icu_mux_irq_demux(struct irq_desc *desc)
 			generic_handle_irq(icu_data[i].virq_base + n);
 		}
 	}
+
+out:
+	chained_irq_exit(chip, desc);
 }
 
 static int mmp_irq_domain_map(struct irq_domain *d, unsigned int irq,