irqchip: crossbar: Introduce ti, max-crossbar-sources to identify valid crossbar mapping

Currently we attempt to map any crossbar value to an IRQ, however,
this is not correct from hardware perspective. There is a max crossbar
event number upto which hardware supports. So describe the same in
device tree using 'ti,max-crossbar-sources' property and use it to
validate requests.

[ jac - remove MAX_SOURCES from binding doc, use integer because we
shouldn't put implementation details in the binding docs ]

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Sricharan R <r.sricharan@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Link: https://lkml.kernel.org/r/1403766634-18543-14-git-send-email-r.sricharan@ti.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

Documentation/devicetree/bindings/arm/omap/crossbar.txt

@@ -10,6 +10,7 @@ Required properties:
 - compatible : Should be "ti,irq-crossbar"
 - reg: Base address and the size of the crossbar registers.
 - ti,max-irqs: Total number of irqs available at the interrupt controller.
+- ti,max-crossbar-sources: Maximum number of crossbar sources that can be routed.
 - ti,reg-size: Size of a individual register in bytes. Every individual
 	    register is assumed to be of same size. Valid sizes are 1, 2, 4.
 - ti,irqs-reserved: List of the reserved irq lines that are not muxed using
@@ -30,6 +31,7 @@ Examples:
 			compatible = "ti,irq-crossbar";
 			reg = <0x4a002a48 0x130>;
 			ti,max-irqs = <160>;
+			ti,max-crossbar-sources = <400>;
 			ti,reg-size = <2>;
 			ti,irqs-reserved = <0 1 2 3 5 6 131 132 139 140>;
 			ti,irqs-skip = <10 133 139 140>;

drivers/irqchip/irq-crossbar.c

@@ -26,6 +26,7 @@
  * struct crossbar_device - crossbar device description
  * @int_max: maximum number of supported interrupts
  * @safe_map: safe default value to initialize the crossbar
+ * @max_crossbar_sources: Maximum number of crossbar sources
  * @irq_map: array of interrupts to crossbar number mapping
  * @crossbar_base: crossbar base address
  * @register_offsets: offsets for each irq number
@@ -34,6 +35,7 @@
 struct crossbar_device {
 	uint int_max;
 	uint safe_map;
+	uint max_crossbar_sources;
 	uint *irq_map;
 	void __iomem *crossbar_base;
 	int *register_offsets;
@@ -117,12 +119,19 @@ static int crossbar_domain_xlate(struct irq_domain *d,
 				 unsigned int *out_type)
 {
 	int ret;
+	int req_num = intspec[1];
 
-	ret = get_prev_map_irq(intspec[1]);
+	if (req_num >= cb->max_crossbar_sources) {
+		pr_err("%s: requested crossbar number %d > max %d\n",
+		       __func__, req_num, cb->max_crossbar_sources);
+		return -EINVAL;
+	}
+
+	ret = get_prev_map_irq(req_num);
 	if (ret >= 0)
 		goto found;
 
-	ret = allocate_free_irq(intspec[1]);
+	ret = allocate_free_irq(req_num);
 
 	if (ret < 0)
 		return ret;
@@ -153,6 +162,14 @@ static int __init crossbar_of_init(struct device_node *node)
 	if (!cb->crossbar_base)
 		goto err_cb;
 
+	of_property_read_u32(node, "ti,max-crossbar-sources",
+			     &cb->max_crossbar_sources);
+	if (!cb->max_crossbar_sources) {
+		pr_err("missing 'ti,max-crossbar-sources' property\n");
+		ret = -EINVAL;
+		goto err_base;
+	}
+
 	of_property_read_u32(node, "ti,max-irqs", &max);
 	if (!max) {
 		pr_err("missing 'ti,max-irqs' property\n");