Support the NVIC interrupt controller as node parent of the MSCM
interrupt router. On the dual-core variants of Vybird (VF6xx), the
NVIC interrupt controller is used by the Cortex-M4. To support
running Linux on this core too, MSCM needs NVIC parent support too.

Signed-off-by: Stefan Agner <stefan@agner.ch>
---
 drivers/irqchip/irq-vf610-mscm-ir.c | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/drivers/irqchip/irq-vf610-mscm-ir.c b/drivers/irqchip/irq-vf610-mscm-ir.c
index 9521057..bb0e1a3 100644
--- a/drivers/irqchip/irq-vf610-mscm-ir.c
+++ b/drivers/irqchip/irq-vf610-mscm-ir.c

@@ -101,17 +103,25 @@ static void vf610_mscm_ir_enable(struct irq_data *data)
 	writew_relaxed(chip_data->cpu_mask,
 		       chip_data->mscm_ir_base + MSCM_IRSPRC(hwirq));
 
-	irq_chip_unmask_parent(data);
+	if (parent->chip->irq_enable)
+		parent->chip->irq_enable(parent);
+	else
+		parent->chip->irq_unmask(parent);
+
 }
 
 static void vf610_mscm_ir_disable(struct irq_data *data)
 {
 	irq_hw_number_t hwirq = data->hwirq;
 	struct vf610_mscm_ir_chip_data *chip_data = data->chip_data;
+	struct irq_data *parent = data->parent_data;
 
 	writew_relaxed(0x0, chip_data->mscm_ir_base + MSCM_IRSPRC(hwirq));
 
-	irq_chip_mask_parent(data);
+	if (parent->chip->irq_enable)
+		parent->chip->irq_disable(parent);

@@ -143,10 +153,17 @@ static int vf610_mscm_ir_domain_alloc(struct irq_domain *domain, unsigned int vi
 					      domain->host_data);
 
 	gic_data.np = domain->parent->of_node;
-	gic_data.args_count = 3;
-	gic_data.args[0] = GIC_SPI;
-	gic_data.args[1] = irq_data->args[0];
-	gic_data.args[2] = irq_data->args[1];
+
+	if (mscm_ir_data->is_nvic) {
+		gic_data.args_count = 1;
+		gic_data.args[0] = irq_data->args[0];
+	} else {
+		gic_data.args_count = 3;
+		gic_data.args[0] = GIC_SPI;
+		gic_data.args[1] = irq_data->args[0];
+		gic_data.args[2] = irq_data->args[1];
+	}
+
 	return irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, &gic_data);
 }
 

@@ -199,6 +216,9 @@ static int __init vf610_mscm_ir_of_init(struct device_node *node,
 		goto out_unmap;
 	}
 
+	if (of_device_is_compatible(domain->parent->of_node, "arm,armv7m-nvic"))
+		mscm_ir_data->is_nvic = true;
+