irqchip/sifive-plic: Support irq domain hierarchy

Add support for hierarchical irq domains. This is needed as
pre-requisite for gpio-sifive driver.
Signed-off-by: Yash Shah <yash.shah@sifive.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1575976274-13487-4-git-send-email-yash.shah@sifive.com

drivers/irqchip/Kconfig

@@ -490,6 +490,7 @@ config TI_SCI_INTA_IRQCHIP
 config SIFIVE_PLIC
 	bool "SiFive Platform-Level Interrupt Controller"
 	depends on RISCV
+	select IRQ_DOMAIN_HIERARCHY
 	help
 	   This enables support for the PLIC chip found in SiFive (and
 	   potentially other) RISC-V systems.  The PLIC controls devices

drivers/irqchip/irq-sifive-plic.c

@@ -154,15 +154,37 @@ static struct irq_chip plic_chip = {
 static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
 			      irq_hw_number_t hwirq)
 {
-	irq_set_chip_and_handler(irq, &plic_chip, handle_fasteoi_irq);
-	irq_set_chip_data(irq, NULL);
+	irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data,
+			    handle_fasteoi_irq, NULL, NULL);
 	irq_set_noprobe(irq);
 	return 0;
 }
 
+static int plic_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
+				 unsigned int nr_irqs, void *arg)
+{
+	int i, ret;
+	irq_hw_number_t hwirq;
+	unsigned int type;
+	struct irq_fwspec *fwspec = arg;
+
+	ret = irq_domain_translate_onecell(domain, fwspec, &hwirq, &type);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < nr_irqs; i++) {
+		ret = plic_irqdomain_map(domain, virq + i, hwirq + i);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 static const struct irq_domain_ops plic_irqdomain_ops = {
-	.map		= plic_irqdomain_map,
-	.xlate		= irq_domain_xlate_onecell,
+	.translate	= irq_domain_translate_onecell,
+	.alloc		= plic_irq_domain_alloc,
+	.free		= irq_domain_free_irqs_top,
 };
 
 static struct irq_domain *plic_irqdomain;