[PATCH v2 7/8] firmware: smccc: lfa: Register DT interrupt

[Andre Przywara <andre.przywara@arm.com>]

The Arm Live Firmware Activation spec describes an asynchronous
notification mechanism, where the platform can notify the host OS about
newly pending image updates.
In the absence of the ACPI notification mechanism also a simple
devicetree node can describe an interrupt.

Add code to find the respective DT node and register the specified
interrupt, to trigger the activation if needed.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 drivers/firmware/smccc/lfa_fw.c | 45 +++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/firmware/smccc/lfa_fw.c b/drivers/firmware/smccc/lfa_fw.c
index 5dc531e462eb..ecd056901b8d 100644
--- a/drivers/firmware/smccc/lfa_fw.c
+++ b/drivers/firmware/smccc/lfa_fw.c
@@ -16,6 +16,8 @@
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/nmi.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
 #include <linux/psci.h>
 #include <linux/stop_machine.h>
 #include <linux/string.h>
@@ -841,6 +843,43 @@ static void lfa_remove_acpi(struct device *dev)
 }
 #endif
 
+static irqreturn_t lfa_irq_handler(int irq, void *dev_id)
+{
+	return IRQ_WAKE_THREAD;
+}
+
+static irqreturn_t lfa_irq_handler_thread(int irq, void *dev_id)
+{
+	int ret;
+
+	while (!(ret = activate_pending_image()))
+		;
+
+	if (ret != -ENOENT)
+		pr_warn("notified image activation failed: %d\n", ret);
+
+	return IRQ_HANDLED;
+}
+
+static int lfa_register_dt(struct device *dev)
+{
+	struct device_node *np;
+	unsigned int irq;
+
+	np = of_find_compatible_node(NULL, NULL, "arm,lfa");
+	if (!np)
+		return -ENODEV;
+
+	irq = irq_of_parse_and_map(np, 0);
+	of_node_put(np);
+	if (!irq)
+		return -ENODEV;
+
+	return devm_request_threaded_irq(dev, irq, lfa_irq_handler,
+					 lfa_irq_handler_thread,
+					 IRQF_COND_ONESHOT, NULL, NULL);
+}
+
 static int lfa_faux_probe(struct faux_device *fdev)
 {
 	int ret;
@@ -854,6 +893,12 @@ static int lfa_faux_probe(struct faux_device *fdev)
 		}
 	}
 
+	ret = lfa_register_dt(&fdev->dev);
+	if (!ret)
+		pr_info("registered LFA DT notification interrupt\n");
+	if (ret != -ENODEV)
+		return ret;
+
 	return 0;
 }
 
-- 
2.43.0