[Patch v5 04/12] irqchip: xilinx: Add support for parent intc

[Zubair Lutfullah Kakakhel]

The MIPS based xilfpga platform has the following IRQ structure

Peripherals --> xilinx_intcontroller -> mips_cpu_int controller

Add support for the driver to chain the irq handler

Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel at imgtec.com>

---
V4 -> V5
Rebased to v4.9-rc1
Missing curly braces

V3 -> V4
Clean up if/else when a parent is found
Pass irqchip structure to handler as data

V2 -> V3
Reused existing parent node instead of finding again.
Cleanup up handler based on review

V1 -> V2

No change
---
 drivers/irqchip/irq-xilinx-intc.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-xilinx-intc.c b/drivers/irqchip/irq-xilinx-intc.c
index 45e5154..dbf8b0c 100644
--- a/drivers/irqchip/irq-xilinx-intc.c
+++ b/drivers/irqchip/irq-xilinx-intc.c
@@ -15,6 +15,7 @@
 #include <linux/of_address.h>
 #include <linux/io.h>
 #include <linux/bug.h>
+#include <linux/of_irq.h>
 
 /* No one else should require these constants, so define them locally here. */
 #define ISR 0x00			/* Interrupt Status Register */
@@ -154,11 +155,23 @@ static int xintc_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hw)
 	.map = xintc_map,
 };
 
+static void xil_intc_irq_handler(struct irq_desc *desc)
+{
+	u32 pending;
+
+	do {
+		pending = xintc_get_irq();
+		if (pending == -1U)
+			break;
+		generic_handle_irq(pending);
+	} while (true);
+}
+
 static int __init xilinx_intc_of_init(struct device_node *intc,
 					     struct device_node *parent)
 {
 	u32 nr_irq;
-	int ret;
+	int ret, irq;
 	struct xintc_irq_chip *irqc;
 
 	if (xintc_irqc) {
@@ -221,7 +234,16 @@ static int __init xilinx_intc_of_init(struct device_node *intc,
 		goto err_alloc;
 	}
 
-	irq_set_default_host(root_domain);
+	if (parent) {
+		irq = irq_of_parse_and_map(intc, 0);
+		if (irq)
+			irq_set_chained_handler_and_data(irq,
+							 xil_intc_irq_handler,
+							 irqc);
+
+	} else {
+		irq_set_default_host(root_domain);
+	}
 
 	return 0;
 
-- 
1.9.1