[PATCH 03/12] irqchip/stm32-exti: Map interrupts through interrupt nexus node

[Antonio Borneo <antonio.borneo@xxxxxxxxxxx>]

The mapping of EXTI interrupts to its parent interrupt controller
is both SoC and instance dependent.
The current implementation requires adding a new table to the
driver's code and a new compatible for each new EXTI instance.

Check for the presence of the optional interrupt nexus child node
and use its property 'interrup-map' to map EXTI interrupts to the
parent's interrupts.

For old DT's without the optional nexus child node, the driver's
behavior is unchanged, thus keeps backward compatibility.

Signed-off-by: Antonio Borneo <antonio.borneo@xxxxxxxxxxx>
---
 drivers/irqchip/irq-stm32-exti.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-stm32-exti.c b/drivers/irqchip/irq-stm32-exti.c
index 69982f21126a..95bb3dd10b2c 100644
--- a/drivers/irqchip/irq-stm32-exti.c
+++ b/drivers/irqchip/irq-stm32-exti.c
@@ -61,6 +61,7 @@ struct stm32_exti_host_data {
 	struct stm32_exti_chip_data *chips_data;
 	const struct stm32_exti_drv_data *drv_data;
 	struct hwspinlock *hwlock;
+	struct device_node *irq_map_node;
 };
 
 static struct stm32_exti_host_data *stm32_host_data;
@@ -713,8 +714,9 @@ static int stm32_exti_h_domain_alloc(struct irq_domain *dm,
 	u8 desc_irq;
 	struct irq_fwspec *fwspec = data;
 	struct irq_fwspec p_fwspec;
+	struct of_phandle_args out_irq;
 	irq_hw_number_t hwirq;
-	int bank;
+	int bank, ret;
 	u32 event_trg;
 	struct irq_chip *chip;
 
@@ -731,6 +733,25 @@ static int stm32_exti_h_domain_alloc(struct irq_domain *dm,
 
 	irq_domain_set_hwirq_and_chip(dm, virq, hwirq, chip, chip_data);
 
+	if (host_data->irq_map_node) {
+		out_irq.np = host_data->irq_map_node;
+		out_irq.args_count = 2;
+		out_irq.args[0] = fwspec->param[0];
+		out_irq.args[1] = fwspec->param[1];
+
+		ret = of_irq_parse_raw(NULL, &out_irq);
+		if (ret)
+			return ret;
+		/* we only support one parent, so far */
+		if (of_node_to_fwnode(out_irq.np) != dm->parent->fwnode)
+			return -EINVAL;
+
+		of_phandle_args_to_fwspec(out_irq.np, out_irq.args,
+					  out_irq.args_count, &p_fwspec);
+
+		return irq_domain_alloc_irqs_parent(dm, virq, 1, &p_fwspec);
+	}
+
 	if (!host_data->drv_data->desc_irqs)
 		return -EINVAL;
 
@@ -908,7 +929,7 @@ static int stm32_exti_probe(struct platform_device *pdev)
 {
 	int ret, i;
 	struct device *dev = &pdev->dev;
-	struct device_node *np = dev->of_node;
+	struct device_node *child, *np = dev->of_node;
 	struct irq_domain *parent_domain, *domain;
 	struct stm32_exti_host_data *host_data;
 	const struct stm32_exti_drv_data *drv_data;
@@ -976,6 +997,10 @@ static int stm32_exti_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	child = of_get_child_by_name(np, "exti-interrupt-map");
+	if (child && of_property_read_bool(child, "interrupt-map"))
+		host_data->irq_map_node = child;
+
 	stm32_exti_h_syscore_init(host_data);
 
 	return 0;
-- 
2.34.1