irqchip/loongson-eiointc: Add suspend/resume support

Add suspend/resume support for EIOINTC irqchip, which is needed for
upcoming suspend/hibernation.
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221020073527.541845-3-chenhuacai@loongson.cn

drivers/irqchip/irq-loongson-eiointc.c

@@ -17,6 +17,7 @@
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
+#include <linux/syscore_ops.h>
 
 #define EIOINTC_REG_NODEMAP	0x14a0
 #define EIOINTC_REG_IPMAP	0x14c0
@@ -301,6 +302,37 @@ static struct irq_domain *acpi_get_vec_parent(int node, struct acpi_vector_group
 	return NULL;
 }
 
+static int eiointc_suspend(void)
+{
+	return 0;
+}
+
+static void eiointc_resume(void)
+{
+	int i, j;
+	struct irq_desc *desc;
+	struct irq_data *irq_data;
+
+	eiointc_router_init(0);
+
+	for (i = 0; i < nr_pics; i++) {
+		for (j = 0; j < VEC_COUNT; j++) {
+			desc = irq_resolve_mapping(eiointc_priv[i]->eiointc_domain, j);
+			if (desc && desc->handle_irq && desc->handle_irq != handle_bad_irq) {
+				raw_spin_lock(&desc->lock);
+				irq_data = &desc->irq_data;
+				eiointc_set_irq_affinity(irq_data, irq_data->common->affinity, 0);
+				raw_spin_unlock(&desc->lock);
+			}
+		}
+	}
+}
+
+static struct syscore_ops eiointc_syscore_ops = {
+	.suspend = eiointc_suspend,
+	.resume = eiointc_resume,
+};
+
 static int __init
 pch_pic_parse_madt(union acpi_subtable_headers *header,
 		       const unsigned long end)
@@ -380,6 +412,7 @@ int __init eiointc_acpi_init(struct irq_domain *parent,
 	parent_irq = irq_create_mapping(parent, acpi_eiointc->cascade);
 	irq_set_chained_handler_and_data(parent_irq, eiointc_irq_dispatch, priv);
 
+	register_syscore_ops(&eiointc_syscore_ops);
 	cpuhp_setup_state_nocalls(CPUHP_AP_IRQ_LOONGARCH_STARTING,
 				  "irqchip/loongarch/intc:starting",
 				  eiointc_router_init, NULL);