[RFC PATCH 2/3] irqchip/exiu: implement ACPI gpiolib/irqchip support

[Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>]

Expose the existing EXIU hierarchical irqchip domain code to permit
the interrupt controller to be used as the irqchip component of a
GPIO controller on ACPI systems.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
 drivers/irqchip/irq-sni-exiu.c | 82 +++++++++++++++++---
 1 file changed, 73 insertions(+), 9 deletions(-)

diff --git a/drivers/irqchip/irq-sni-exiu.c b/drivers/irqchip/irq-sni-exiu.c
index 52ce662334d4..99351cf997d9 100644
--- a/drivers/irqchip/irq-sni-exiu.c
+++ b/drivers/irqchip/irq-sni-exiu.c
@@ -12,6 +12,7 @@
  * published by the Free Software Foundation.
  */
 
+#include <linux/gpio/driver.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/irq.h>
@@ -20,6 +21,7 @@
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
+#include <linux/platform_device.h>
 
 #include <dt-bindings/interrupt-controller/arm-gic.h>
 
@@ -134,9 +136,13 @@ static int exiu_domain_translate(struct irq_domain *domain,
 
 		*hwirq = fwspec->param[1] - info->spi_base;
 		*type = fwspec->param[2] & IRQ_TYPE_SENSE_MASK;
-		return 0;
+	} else {
+		if (fwspec->param_count != 2)
+			return -EINVAL;
+		*hwirq = fwspec->param[0];
+		*type = fwspec->param[2] & IRQ_TYPE_SENSE_MASK;
 	}
-	return -EINVAL;
+	return 0;
 }
 
 static int exiu_domain_alloc(struct irq_domain *dom, unsigned int virq,
@@ -147,16 +153,23 @@ static int exiu_domain_alloc(struct irq_domain *dom, unsigned int virq,
 	struct exiu_irq_data *info = dom->host_data;
 	irq_hw_number_t hwirq;
 
-	if (fwspec->param_count != 3)
-		return -EINVAL;	/* Not GIC compliant */
-	if (fwspec->param[0] != GIC_SPI)
-		return -EINVAL;	/* No PPI should point to this domain */
-
+	parent_fwspec = *fwspec;
+	if (is_of_node(dom->parent->fwnode)) {
+		if (fwspec->param_count != 3)
+			return -EINVAL;	/* Not GIC compliant */
+		if (fwspec->param[0] != GIC_SPI)
+			return -EINVAL;	/* No PPI should point to this domain */
+
+		hwirq = fwspec->param[1] - info->spi_base;
+	} else if (is_fwnode_irqchip(dom->parent->fwnode)) {
+		hwirq = fwspec->param[0];
+		parent_fwspec.param[0] = hwirq + info->spi_base + 32;
+	} else {
+		return -EINVAL;
+	}
 	WARN_ON(nr_irqs != 1);
-	hwirq = fwspec->param[1] - info->spi_base;
 	irq_domain_set_hwirq_and_chip(dom, virq, hwirq, &exiu_irq_chip, info);
 
-	parent_fwspec = *fwspec;
 	parent_fwspec.fwnode = dom->parent->fwnode;
 	return irq_domain_alloc_irqs_parent(dom, virq, nr_irqs, &parent_fwspec);
 }
@@ -244,3 +257,54 @@ static int __init exiu_dt_init(struct device_node *node,
 	return 0;
 }
 IRQCHIP_DECLARE(exiu, "socionext,synquacer-exiu", exiu_dt_init);
+
+#ifdef CONFIG_ACPI
+static int exiu_acpi_gpio_to_irq(struct gpio_chip *gc, u32 gpio)
+{
+	struct irq_fwspec fwspec;
+
+	fwspec.fwnode		= gc->parent->fwnode;
+	fwspec.param_count	= 2;
+	fwspec.param[0]		= gpio;
+	fwspec.param[1]		= IRQ_TYPE_LEVEL_HIGH;
+
+	return irq_create_fwspec_mapping(&fwspec);
+}
+
+int exiu_acpi_init(struct platform_device *pdev, struct gpio_chip *gc)
+{
+	struct irq_domain *parent_domain = NULL, *domain;
+	struct resource *res;
+	int irq;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq > 0)
+		parent_domain = irq_get_irq_data(irq)->domain;
+
+	if (!parent_domain) {
+		dev_err(&pdev->dev, "unable to obtain parent domain\n");
+		return -ENODEV;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (!res) {
+		dev_err(&pdev->dev, "failed to parse memory resource\n");
+		return -ENXIO;
+	}
+
+	domain = exiu_init(parent_domain, dev_fwnode(&pdev->dev), res);
+	if (IS_ERR(domain)) {
+		dev_err(&pdev->dev, "failed to create IRQ domain (%ld)\n",
+			PTR_ERR(domain));
+		return PTR_ERR(domain);
+	}
+
+	gc->irq.domain = domain;
+	gc->to_irq = exiu_acpi_gpio_to_irq;
+
+	dev_info(&pdev->dev, "%d interrupts forwarded\n", NUM_IRQS);
+
+	return 0;
+}
+EXPORT_SYMBOL(exiu_acpi_init);
+#endif
-- 
2.20.1