[PATCH v2 4/4] amba: Properly handle device probe without IRQ domain

[Kefeng Wang <wangkefeng.wang@huawei.com>]

of_amba_device_create() uses irq_of_parse_and_map() to translate
a DT interrupt specification into a Linux virtual interrupt number.

But it doesn't properly handle the case where the interrupt controller
is not yet available, eg, when pl011 interrupt is connected to MBIGEN
interrupt controller, because the mbigen initialization is too late,
which will lead to no IRQ due to no IRQ domain found, log is shown below,
  "irq: no irq domain found for uart0 !"

use of_irq_get() to return -EPROBE_DEFER as above, and in the driver
deferred probe, it will properly handle in such case, also return 0
in other fail cases to be consistent as before.

Cc: Russell King <linux@armlinux.org.uk>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Reported-by: Ruizhe Lin <linruizhe@huawei.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 drivers/amba/bus.c    | 27 +++++++++++++++++++++++++++
 drivers/of/platform.c |  6 +-----
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 4d3a565ca079..96e84ce66e9a 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -19,6 +19,7 @@
 #include <linux/clk/clk-conf.h>
 #include <linux/platform_device.h>
 #include <linux/reset.h>
+#include <linux/of_irq.h>
 
 #define to_amba_driver(d)	container_of(d, struct amba_driver, drv)
 
@@ -170,6 +171,28 @@ static int amba_uevent(struct device *dev, struct kobj_uevent_env *env)
 	return retval;
 }
 
+static int of_amba_device_decode_irq(struct amba_device *dev)
+{
+	struct device_node *node = dev->dev.of_node;
+	int i, irq;
+
+	if (IS_ENABLED(CONFIG_OF_IRQ) && node) {
+		/* Decode the IRQs and address ranges */
+		for (i = 0; i < AMBA_NR_IRQS; i++) {
+			irq = of_irq_get(node, i);
+			if (irq < 0) {
+				if (irq == -EPROBE_DEFER)
+					return irq;
+				irq = 0;
+			}
+
+			dev->irq[i] = irq;
+		}
+	}
+
+	return 0;
+}
+
 /*
  * These are the device model conversion veneers; they convert the
  * device model structures to our more specific structures.
@@ -182,6 +205,10 @@ static int amba_probe(struct device *dev)
 	int ret;
 
 	do {
+		ret = of_amba_device_decode_irq(pcdev);
+		if (ret)
+			break;
+
 		ret = of_clk_set_defaults(dev->of_node, false);
 		if (ret < 0)
 			break;
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index 74afbb7a4f5e..32d5ff8df747 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -222,7 +222,7 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
 {
 	struct amba_device *dev;
 	const void *prop;
-	int i, ret;
+	int ret;
 
 	pr_debug("Creating amba device %pOF\n", node);
 
@@ -253,10 +253,6 @@ static struct amba_device *of_amba_device_create(struct device_node *node,
 	if (prop)
 		dev->periphid = of_read_ulong(prop, 1);
 
-	/* Decode the IRQs and address ranges */
-	for (i = 0; i < AMBA_NR_IRQS; i++)
-		dev->irq[i] = irq_of_parse_and_map(node, i);
-
 	ret = of_address_to_resource(node, 0, &dev->res);
 	if (ret) {
 		pr_err("amba: of_address_to_resource() failed (%d) for %pOF\n",
-- 
2.18.0.huawei.25