irqchip/mips-gic: Only register IPI domain when SMP is enabled

The MIPS GIC irqchip driver may be selected in a uniprocessor
configuration, but it unconditionally registers an IPI domain.

Limit the part of the driver dealing with IPIs to only be compiled when
GENERIC_IRQ_IPI is enabled, which corresponds to an SMP configuration.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220701200056.46555-2-samuel@sholland.org

drivers/irqchip/Kconfig

@@ -322,7 +322,8 @@ config KEYSTONE_IRQ
 
 config MIPS_GIC
 	bool
-	select GENERIC_IRQ_IPI
+	select GENERIC_IRQ_IPI if SMP
+	select IRQ_DOMAIN_HIERARCHY
 	select MIPS_CM
 
 config INGENIC_IRQ

drivers/irqchip/irq-mips-gic.c

@@ -52,13 +52,15 @@ static DEFINE_PER_CPU_READ_MOSTLY(unsigned long[GIC_MAX_LONGS], pcpu_masks);
 
 static DEFINE_SPINLOCK(gic_lock);
 static struct irq_domain *gic_irq_domain;
-static struct irq_domain *gic_ipi_domain;
 static int gic_shared_intrs;
 static unsigned int gic_cpu_pin;
 static unsigned int timer_cpu_pin;
 static struct irq_chip gic_level_irq_controller, gic_edge_irq_controller;
+
+#ifdef CONFIG_GENERIC_IRQ_IPI
 static DECLARE_BITMAP(ipi_resrv, GIC_MAX_INTRS);
 static DECLARE_BITMAP(ipi_available, GIC_MAX_INTRS);
+#endif /* CONFIG_GENERIC_IRQ_IPI */
 
 static struct gic_all_vpes_chip_data {
 	u32	map;
@@ -472,9 +474,11 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int virq,
 	u32 map;
 
 	if (hwirq >= GIC_SHARED_HWIRQ_BASE) {
+#ifdef CONFIG_GENERIC_IRQ_IPI
 		/* verify that shared irqs don't conflict with an IPI irq */
 		if (test_bit(GIC_HWIRQ_TO_SHARED(hwirq), ipi_resrv))
 			return -EBUSY;
+#endif /* CONFIG_GENERIC_IRQ_IPI */
 
 		err = irq_domain_set_hwirq_and_chip(d, virq, hwirq,
 						    &gic_level_irq_controller,
@@ -567,6 +571,8 @@ static const struct irq_domain_ops gic_irq_domain_ops = {
 	.map = gic_irq_domain_map,
 };
 
+#ifdef CONFIG_GENERIC_IRQ_IPI
+
 static int gic_ipi_domain_xlate(struct irq_domain *d, struct device_node *ctrlr,
 				const u32 *intspec, unsigned int intsize,
 				irq_hw_number_t *out_hwirq,
@@ -670,6 +676,48 @@ static const struct irq_domain_ops gic_ipi_domain_ops = {
 	.match = gic_ipi_domain_match,
 };
 
+static int gic_register_ipi_domain(struct device_node *node)
+{
+	struct irq_domain *gic_ipi_domain;
+	unsigned int v[2], num_ipis;
+
+	gic_ipi_domain = irq_domain_add_hierarchy(gic_irq_domain,
+						  IRQ_DOMAIN_FLAG_IPI_PER_CPU,
+						  GIC_NUM_LOCAL_INTRS + gic_shared_intrs,
+						  node, &gic_ipi_domain_ops, NULL);
+	if (!gic_ipi_domain) {
+		pr_err("Failed to add IPI domain");
+		return -ENXIO;
+	}
+
+	irq_domain_update_bus_token(gic_ipi_domain, DOMAIN_BUS_IPI);
+
+	if (node &&
+	    !of_property_read_u32_array(node, "mti,reserved-ipi-vectors", v, 2)) {
+		bitmap_set(ipi_resrv, v[0], v[1]);
+	} else {
+		/*
+		 * Reserve 2 interrupts per possible CPU/VP for use as IPIs,
+		 * meeting the requirements of arch/mips SMP.
+		 */
+		num_ipis = 2 * num_possible_cpus();
+		bitmap_set(ipi_resrv, gic_shared_intrs - num_ipis, num_ipis);
+	}
+
+	bitmap_copy(ipi_available, ipi_resrv, GIC_MAX_INTRS);
+
+	return 0;
+}
+
+#else /* !CONFIG_GENERIC_IRQ_IPI */
+
+static inline int gic_register_ipi_domain(struct device_node *node)
+{
+	return 0;
+}
+
+#endif /* !CONFIG_GENERIC_IRQ_IPI */
+
 static int gic_cpu_startup(unsigned int cpu)
 {
 	/* Enable or disable EIC */
@@ -688,11 +736,12 @@ static int gic_cpu_startup(unsigned int cpu)
 static int __init gic_of_init(struct device_node *node,
 			      struct device_node *parent)
 {
-	unsigned int cpu_vec, i, gicconfig, v[2], num_ipis;
+	unsigned int cpu_vec, i, gicconfig;
 	unsigned long reserved;
 	phys_addr_t gic_base;
 	struct resource res;
 	size_t gic_len;
+	int ret;
 
 	/* Find the first available CPU vector. */
 	i = 0;
@@ -780,30 +829,9 @@ static int __init gic_of_init(struct device_node *node,
 		return -ENXIO;
 	}
 
-	gic_ipi_domain = irq_domain_add_hierarchy(gic_irq_domain,
-						  IRQ_DOMAIN_FLAG_IPI_PER_CPU,
-						  GIC_NUM_LOCAL_INTRS + gic_shared_intrs,
-						  node, &gic_ipi_domain_ops, NULL);
-	if (!gic_ipi_domain) {
-		pr_err("Failed to add IPI domain");
-		return -ENXIO;
-	}
-
-	irq_domain_update_bus_token(gic_ipi_domain, DOMAIN_BUS_IPI);
-
-	if (node &&
-	    !of_property_read_u32_array(node, "mti,reserved-ipi-vectors", v, 2)) {
-		bitmap_set(ipi_resrv, v[0], v[1]);
-	} else {
-		/*
-		 * Reserve 2 interrupts per possible CPU/VP for use as IPIs,
-		 * meeting the requirements of arch/mips SMP.
-		 */
-		num_ipis = 2 * num_possible_cpus();
-		bitmap_set(ipi_resrv, gic_shared_intrs - num_ipis, num_ipis);
-	}
-
-	bitmap_copy(ipi_available, ipi_resrv, GIC_MAX_INTRS);
+	ret = gic_register_ipi_domain(node);
+	if (ret)
+		return ret;
 
 	board_bind_eic_interrupt = &gic_bind_eic_interrupt;