soc/tegra: pmc: Fix crashes for hierarchical interrupts

Interrupts that don't have an associated wake event or GPIO wake events
end up with an associate IRQ chip that is NULL and which causes IRQ code
to crash. This is because we don't implicitly set the parent IRQ chip by
allocating the interrupt at the parent. However, there really isn't a
corresponding interrupt at the parent, so we need to work around this by
setting the special no_irq_chip as the IRQ chip for these interrupts.

Fixes: 19906e6 ("soc/tegra: pmc: Add wake event support")
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/soc/tegra/pmc.c

@@ -1899,6 +1899,20 @@ static int tegra_pmc_irq_alloc(struct irq_domain *domain, unsigned int virq,
 							    event->id,
 							    &pmc->irq, pmc);
 
+			/*
+			 * GPIOs don't have an equivalent interrupt in the
+			 * parent controller (GIC). However some code, such
+			 * as the one in irq_get_irqchip_state(), require a
+			 * valid IRQ chip to be set. Make sure that's the
+			 * case by passing NULL here, which will install a
+			 * dummy IRQ chip for the interrupt in the parent
+			 * domain.
+			 */
+			if (domain->parent)
+				irq_domain_set_hwirq_and_chip(domain->parent,
+							      virq, 0, NULL,
+							      NULL);
+
 			break;
 		}
 	}
@@ -1908,10 +1922,22 @@ static int tegra_pmc_irq_alloc(struct irq_domain *domain, unsigned int virq,
 	 * dummy hardware IRQ number. This is used in the ->irq_set_type()
 	 * and ->irq_set_wake() callbacks to return early for these IRQs.
 	 */
-	if (i == soc->num_wake_events)
+	if (i == soc->num_wake_events) {
 		err = irq_domain_set_hwirq_and_chip(domain, virq, ULONG_MAX,
 						    &pmc->irq, pmc);
 
+		/*
+		 * Interrupts without a wake event don't have a corresponding
+		 * interrupt in the parent controller (GIC). Pass NULL for the
+		 * chip here, which causes a dummy IRQ chip to be installed
+		 * for the interrupt in the parent domain, to make this
+		 * explicit.
+		 */
+		if (domain->parent)
+			irq_domain_set_hwirq_and_chip(domain->parent, virq, 0,
+						      NULL, NULL);
+	}
+
 	return err;
 }