irqchip/exiu: Implement ACPI support

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, or as the target of ordinary
interrupt resources.

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/irq-sni-exiu.c

@@ -20,6 +20,7 @@
 #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 +135,13 @@ 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 +152,21 @@ 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)
+	parent_fwspec = *fwspec;
-		return -EINVAL;	/* Not GIC compliant */
+	if (is_of_node(dom->parent->fwnode)) {
-	if (fwspec->param[0] != GIC_SPI)
+		if (fwspec->param_count != 3)
-		return -EINVAL;	/* No PPI should point to this domain */
+			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 {
+		hwirq = fwspec->param[0];
+		parent_fwspec.param[0] = hwirq + info->spi_base + 32;
+	}
 	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);
 }
@@ -245,3 +255,53 @@ out_unmap:
 	return -ENOMEM;
 }
 IRQCHIP_DECLARE(exiu, "socionext,synquacer-exiu", exiu_dt_init);
+
+#ifdef CONFIG_ACPI
+static int exiu_acpi_probe(struct platform_device *pdev)
+{
+	struct irq_domain *domain;
+	struct exiu_irq_data *data;
+	struct resource *res;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "failed to parse memory resource\n");
+		return -ENXIO;
+	}
+
+	data = exiu_init(dev_fwnode(&pdev->dev), res);
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	domain = acpi_irq_create_hierarchy(0, NUM_IRQS, dev_fwnode(&pdev->dev),
+					   &exiu_domain_ops, data);
+	if (!domain) {
+		dev_err(&pdev->dev, "failed to create IRQ domain\n");
+		goto out_unmap;
+	}
+
+	dev_info(&pdev->dev, "%d interrupts forwarded\n", NUM_IRQS);
+
+	return 0;
+
+out_unmap:
+	iounmap(data->base);
+	kfree(data);
+	return -ENOMEM;
+}
+
+static const struct acpi_device_id exiu_acpi_ids[] = {
+	{ "SCX0008" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(acpi, exiu_acpi_ids);
+
+static struct platform_driver exiu_driver = {
+	.driver = {
+		.name = "exiu",
+		.acpi_match_table = exiu_acpi_ids,
+	},
+	.probe = exiu_acpi_probe,
+};
+builtin_platform_driver(exiu_driver);
+#endif