irqchip/loongson-pch-pic: Check return value of irq_domain_translate_twocell()

Check the return value of irq_domain_translate_twocell() due to
it may returns -EINVAL if failed and use variable fwspec for it,
and then use a new variable parent_fwspec which is proper for
irq_domain_alloc_irqs_parent().

Fixes: ef8c01eb ("irqchip: Add Loongson PCH PIC controller")
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1594087972-21715-6-git-send-email-yangtiezhu@loongson.cn

drivers/irqchip/irq-loongson-pch-pic.c

@@ -135,16 +135,19 @@ static int pch_pic_alloc(struct irq_domain *domain, unsigned int virq,
 	int err;
 	unsigned int type;
 	unsigned long hwirq;
-	struct irq_fwspec fwspec;
+	struct irq_fwspec *fwspec = arg;
+	struct irq_fwspec parent_fwspec;
 	struct pch_pic *priv = domain->host_data;
 
-	irq_domain_translate_twocell(domain, arg, &hwirq, &type);
+	err = irq_domain_translate_twocell(domain, fwspec, &hwirq, &type);
+	if (err)
+		return err;
 
-	fwspec.fwnode = domain->parent->fwnode;
-	fwspec.param_count = 1;
-	fwspec.param[0] = hwirq + priv->ht_vec_base;
+	parent_fwspec.fwnode = domain->parent->fwnode;
+	parent_fwspec.param_count = 1;
+	parent_fwspec.param[0] = hwirq + priv->ht_vec_base;
 
-	err = irq_domain_alloc_irqs_parent(domain, virq, 1, &fwspec);
+	err = irq_domain_alloc_irqs_parent(domain, virq, 1, &parent_fwspec);
 	if (err)
 		return err;