ARM: EXYNOS: Add device tree support for interrupt combiner

Add device tree based instantiation of the interrupt combiner controller.
Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

Documentation/devicetree/bindings/arm/samsung/interrupt-combiner.txt

+* Samsung Exynos Interrupt Combiner Controller
+
+Samsung's Exynos4 architecture includes a interrupt combiner controller which
+can combine interrupt sources as a group and provide a single interrupt request
+for the group. The interrupt request from each group are connected to a parent
+interrupt controller, such as GIC in case of Exynos4210.
+
+The interrupt combiner controller consists of multiple combiners. Upto eight
+interrupt sources can be connected to a combiner. The combiner outputs one
+combined interrupt for its eight interrupt sources. The combined interrupt
+is usually connected to a parent interrupt controller.
+
+A single node in the device tree is used to describe the interrupt combiner
+controller module (which includes multiple combiners). A combiner in the
+interrupt controller module shares config/control registers with other
+combiners. For example, a 32-bit interrupt enable/disable config register
+can accommodate upto 4 interrupt combiners (with each combiner supporting
+upto 8 interrupt sources).
+
+Required properties:
+- compatible: should be "samsung,exynos4210-combiner".
+- interrupt-controller: Identifies the node as an interrupt controller.
+- #interrupt-cells: should be <2>. The meaning of the cells are
+	* First Cell: Combiner Group Number.
+	* Second Cell: Interrupt number within the group.
+- reg: Base address and size of interrupt combiner registers.
+- interrupts: The list of interrupts generated by the combiners which are then
+    connected to a parent interrupt controller. The format of the interrupt
+    specifier depends in the interrupt parent controller.
+
+Optional properties:
+- samsung,combiner-nr: The number of interrupt combiners supported. If this
+  property is not specified, the default number of combiners is assumed
+  to be 16.
+- interrupt-parent: pHandle of the parent interrupt controller, if not
+  inherited from the parent node.
+
+
+Example:
+
+	The following is a an example from the Exynos4210 SoC dtsi file.
+
+	combiner:interrupt-controller@10440000 {
+		compatible = "samsung,exynos4210-combiner";
+		interrupt-controller;
+		#interrupt-cells = <2>;
+		reg = <0x10440000 0x1000>;
+		interrupts = <0 0 0>, <0 1 0>, <0 2 0>, <0 3 0>,
+			     <0 4 0>, <0 5 0>, <0 6 0>, <0 7 0>,
+			     <0 8 0>, <0 9 0>, <0 10 0>, <0 11 0>,
+			     <0 12 0>, <0 13 0>, <0 14 0>, <0 15 0>;
+	};

arch/arm/mach-exynos/common.c

@@ -21,6 +21,7 @@
 #include <linux/of_irq.h>
 #include <linux/export.h>
 #include <linux/irqdomain.h>
+#include <linux/of_address.h>
 
 #include <asm/proc-fns.h>
 #include <asm/exception.h>
@@ -490,6 +491,35 @@ static void __init combiner_init_one(unsigned int combiner_nr,
 		     base + COMBINER_ENABLE_CLEAR);
 }
 
+#ifdef CONFIG_OF
+static int combiner_irq_domain_xlate(struct irq_domain *d,
+				     struct device_node *controller,
+				     const u32 *intspec, unsigned int intsize,
+				     unsigned long *out_hwirq,
+				     unsigned int *out_type)
+{
+	if (d->of_node != controller)
+		return -EINVAL;
+
+	if (intsize < 2)
+		return -EINVAL;
+
+	*out_hwirq = intspec[0] * MAX_IRQ_IN_COMBINER + intspec[1];
+	*out_type = 0;
+
+	return 0;
+}
+#else
+static int combiner_irq_domain_xlate(struct irq_domain *d,
+				     struct device_node *controller,
+				     const u32 *intspec, unsigned int intsize,
+				     unsigned long *out_hwirq,
+				     unsigned int *out_type)
+{
+	return -EINVAL;
+}
+#endif
+
 static int combiner_irq_domain_map(struct irq_domain *d, unsigned int irq,
 				   irq_hw_number_t hw)
 {
@@ -501,16 +531,26 @@ static int combiner_irq_domain_map(struct irq_domain *d, unsigned int irq,
 }
 
 static struct irq_domain_ops combiner_irq_domain_ops = {
+	.xlate	= combiner_irq_domain_xlate,
 	.map	= combiner_irq_domain_map,
 };
 
 void __init combiner_init(void __iomem *combiner_base, struct device_node *np)
 {
-	int i, irq_base;
+	int i, irq, irq_base;
 	unsigned int max_nr, nr_irq;
 
+	if (np) {
+		if (of_property_read_u32(np, "samsung,combiner-nr", &max_nr)) {
+			pr_warning("%s: number of combiners not specified, "
+				"setting default as %d.\n",
+				__func__, EXYNOS4_MAX_COMBINER_NR);
+			max_nr = EXYNOS4_MAX_COMBINER_NR;
+		}
+	} else {
 		max_nr = soc_is_exynos5250() ? EXYNOS5_MAX_COMBINER_NR :
 						EXYNOS4_MAX_COMBINER_NR;
+	}
 	nr_irq = max_nr * MAX_IRQ_IN_COMBINER;
 
 	irq_base = irq_alloc_descs(COMBINER_IRQ(0, 0), 1, nr_irq, 0);
@@ -528,13 +568,31 @@ void __init combiner_init(void __iomem *combiner_base, struct device_node *np)
 
 	for (i = 0; i < max_nr; i++) {
 		combiner_init_one(i, combiner_base + (i >> 2) * 0x10);
-		combiner_cascade_irq(i, IRQ_SPI(i));
+		irq = np ? irq_of_parse_and_map(np, i) : IRQ_SPI(i);
+		combiner_cascade_irq(i, irq);
 	}
 }
 
 #ifdef CONFIG_OF
+int __init combiner_of_init(struct device_node *np, struct device_node *parent)
+{
+	void __iomem *combiner_base;
+
+	combiner_base = of_iomap(np, 0);
+	if (!combiner_base) {
+		pr_err("%s: failed to map combiner registers\n", __func__);
+		return -ENXIO;
+	}
+
+	combiner_init(combiner_base, np);
+
+	return 0;
+}
+
 static const struct of_device_id exynos4_dt_irq_match[] = {
 	{ .compatible = "arm,cortex-a9-gic", .data = gic_of_init, },
+	{ .compatible = "samsung,exynos4210-combiner",
+			.data = combiner_of_init, },
 	{},
 };
 #endif
@@ -552,6 +610,7 @@ void __init exynos4_init_irq(void)
 		of_irq_init(exynos4_dt_irq_match);
 #endif
 
+	if (!of_have_populated_dt())
 		combiner_init(S5P_VA_COMBINER_BASE, NULL);
 
 	/*
@@ -567,8 +626,6 @@ void __init exynos5_init_irq(void)
 #ifdef CONFIG_OF
 	of_irq_init(exynos4_dt_irq_match);
 #endif
-	combiner_init(S5P_VA_COMBINER_BASE, NULL);
-
 	/*
 	 * The parameters of s5p_init_irq() are for VIC init.
 	 * Theses parameters should be NULL and 0 because EXYNOS4