irqchip/gic: Drop support for secondary GIC in non-DT systems

We do not have any in-tree platform with this pathological setup,
and only a single system (Cavium's cns3xxx) isn't DT aware.

Let's drop the secondary GIC support for now, until we remove
the above horror altogether.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm/mach-cns3xxx/core.c

@@ -90,7 +90,7 @@ void __init cns3xxx_map_io(void)
 /* used by entry-macro.S */
 void __init cns3xxx_init_irq(void)
 {
-	gic_init(0, 29, IOMEM(CNS3XXX_TC11MP_GIC_DIST_BASE_VIRT),
+	gic_init(IOMEM(CNS3XXX_TC11MP_GIC_DIST_BASE_VIRT),
 		 IOMEM(CNS3XXX_TC11MP_GIC_CPU_BASE_VIRT));
 }
 

drivers/irqchip/irq-gic.c

@@ -1089,11 +1089,10 @@ static void gic_init_chip(struct gic_chip_data *gic, struct device *dev,
 #endif
 }
 
-static int gic_init_bases(struct gic_chip_data *gic, int irq_start,
+static int gic_init_bases(struct gic_chip_data *gic,
 			  struct fwnode_handle *handle)
 {
-	irq_hw_number_t hwirq_base;
-	int gic_irqs, irq_base, ret;
+	int gic_irqs, ret;
 
 	if (IS_ENABLED(CONFIG_GIC_NON_BANKED) && gic->percpu_offset) {
 		/* Frankein-GIC without banked registers... */
@@ -1145,28 +1144,21 @@ static int gic_init_bases(struct gic_chip_data *gic, int irq_start,
 	} else {		/* Legacy support */
 		/*
 		 * For primary GICs, skip over SGIs.
-		 * For secondary GICs, skip over PPIs, too.
+		 * No secondary GIC support whatsoever.
 		 */
-		if (gic == &gic_data[0] && (irq_start & 31) > 0) {
-			hwirq_base = 16;
-			if (irq_start != -1)
-				irq_start = (irq_start & ~31) + 16;
-		} else {
-			hwirq_base = 32;
-		}
+		int irq_base;
 
-		gic_irqs -= hwirq_base; /* calculate # of irqs to allocate */
+		gic_irqs -= 16; /* calculate # of irqs to allocate */
 
-		irq_base = irq_alloc_descs(irq_start, 16, gic_irqs,
+		irq_base = irq_alloc_descs(16, 16, gic_irqs,
 					   numa_node_id());
 		if (irq_base < 0) {
-			WARN(1, "Cannot allocate irq_descs @ IRQ%d, assuming pre-allocated\n",
-			     irq_start);
-			irq_base = irq_start;
+			WARN(1, "Cannot allocate irq_descs @ IRQ16, assuming pre-allocated\n");
+			irq_base = 16;
 		}
 
 		gic->domain = irq_domain_add_legacy(NULL, gic_irqs, irq_base,
-					hwirq_base, &gic_irq_domain_ops, gic);
+						    16, &gic_irq_domain_ops, gic);
 	}
 
 	if (WARN_ON(!gic->domain)) {
@@ -1195,7 +1187,6 @@ static int gic_init_bases(struct gic_chip_data *gic, int irq_start,
 }
 
 static int __init __gic_init_bases(struct gic_chip_data *gic,
-				   int irq_start,
 				   struct fwnode_handle *handle)
 {
 	char *name;
@@ -1231,32 +1222,28 @@ static int __init __gic_init_bases(struct gic_chip_data *gic,
 		gic_init_chip(gic, NULL, name, false);
 	}
 
-	ret = gic_init_bases(gic, irq_start, handle);
+	ret = gic_init_bases(gic, handle);
 	if (ret)
 		kfree(name);
 
 	return ret;
 }
 
-void __init gic_init(unsigned int gic_nr, int irq_start,
-		     void __iomem *dist_base, void __iomem *cpu_base)
+void __init gic_init(void __iomem *dist_base, void __iomem *cpu_base)
 {
 	struct gic_chip_data *gic;
 
-	if (WARN_ON(gic_nr >= CONFIG_ARM_GIC_MAX_NR))
-		return;
-
 	/*
 	 * Non-DT/ACPI systems won't run a hypervisor, so let's not
 	 * bother with these...
 	 */
 	static_branch_disable(&supports_deactivate_key);
 
-	gic = &gic_data[gic_nr];
+	gic = &gic_data[0];
 	gic->raw_dist_base = dist_base;
 	gic->raw_cpu_base = cpu_base;
 
-	__gic_init_bases(gic, irq_start, NULL);
+	__gic_init_bases(gic, NULL);
 }
 
 static void gic_teardown(struct gic_chip_data *gic)
@@ -1399,7 +1386,7 @@ int gic_of_init_child(struct device *dev, struct gic_chip_data **gic, int irq)
 	if (ret)
 		return ret;
 
-	ret = gic_init_bases(*gic, -1, &dev->of_node->fwnode);
+	ret = gic_init_bases(*gic, &dev->of_node->fwnode);
 	if (ret) {
 		gic_teardown(*gic);
 		return ret;
@@ -1459,7 +1446,7 @@ gic_of_init(struct device_node *node, struct device_node *parent)
 	if (gic_cnt == 0 && !gic_check_eoimode(node, &gic->raw_cpu_base))
 		static_branch_disable(&supports_deactivate_key);
 
-	ret = __gic_init_bases(gic, -1, &node->fwnode);
+	ret = __gic_init_bases(gic, &node->fwnode);
 	if (ret) {
 		gic_teardown(gic);
 		return ret;
@@ -1650,7 +1637,7 @@ static int __init gic_v2_acpi_init(struct acpi_subtable_header *header,
 		return -ENOMEM;
 	}
 
-	ret = __gic_init_bases(gic, -1, domain_handle);
+	ret = __gic_init_bases(gic, domain_handle);
 	if (ret) {
 		pr_err("Failed to initialise GIC\n");
 		irq_domain_free_fwnode(domain_handle);

include/linux/irqchip/arm-gic.h

@@ -158,8 +158,7 @@ int gic_of_init_child(struct device *dev, struct gic_chip_data **gic, int irq);
  * Legacy platforms not converted to DT yet must use this to init
  * their GIC
  */
-void gic_init(unsigned int nr, int start,
-	      void __iomem *dist , void __iomem *cpu);
+void gic_init(void __iomem *dist , void __iomem *cpu);
 
 int gicv2m_init(struct fwnode_handle *parent_handle,
 		struct irq_domain *parent);