[PATCH 3/3] firmware: arm_ffa: Add support for handling notification pending interrupt(NPI)

[Sudeep Holla]

The FF-A uses the notification pending interrupt to inform the receiver
that it has a pending notification. This is a virtual interrupt and is
used by the following type of receivers:
 1. A guest/VM running under a hypervisor.
 2. An S-EL1 SP running under a S-EL2 SPMC.

The rules that govern the properties of the NPI are the same as the
rules for the SRI with couple of exceptions. If the SRI is not supported,
then an attempt to discover NPI will be made in the driver.

The handling of NPI is also same as the handling of notification for the
self/primary VM with ID 0 except the absence of global notification.

Co-Developed-by: Jens Wiklander <jens.wiklander at linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
---
 drivers/firmware/arm_ffa/driver.c | 43 +++++++++++++++++++++++++++++++--------
 1 file changed, 34 insertions(+), 9 deletions(-)

diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index c299cb9e6889..d50b41a815b9 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -100,6 +100,8 @@ struct ffa_drv_info {
 	bool mem_ops_native;
 	bool bitmap_created;
 	bool notif_enabled;
+	/* Flag to indicate it is Notification pending interrupt */
+	bool irq_is_npi;
 	/* Schedule Receiver(SRI) or Notification pending interrupt(NPI) */
 	unsigned int sr_or_np_irq;
 	unsigned int cpuhp_state;
@@ -1138,6 +1140,15 @@ ffa_self_notif_handle(u16 vcpu, bool is_per_vcpu, void *cb_data)
 			      &info->notif_pcpu_work);
 }
 
+static irqreturn_t npi_handler(int irq, void *irq_data)
+{
+	struct ffa_pcpu_irq *pcpu = irq_data;
+
+	ffa_self_notif_handle(smp_processor_id(), true, pcpu->info);
+
+	return IRQ_HANDLED;
+}
+
 static const struct ffa_info_ops ffa_drv_info_ops = {
 	.api_version_get = ffa_api_version_get,
 	.partition_info_get = ffa_partition_info_get,
@@ -1307,16 +1318,24 @@ static void ffa_sched_recv_irq_work_fn(struct work_struct *work)
 	ffa_notification_info_get();
 }
 
-static int ffa_sr_or_np_irq_map(void)
+static int ffa_sr_or_np_irq_map(bool *irq_is_npi)
 {
 	int ret, irq, intr_id;
 
 	/* The returned intr_id is assumed to be SGI donated to NS world */
 	ret = ffa_features(FFA_FEAT_SCHEDULE_RECEIVER_INT, 0, &intr_id, NULL);
-	if (ret < 0) {
-		if (ret != -EOPNOTSUPP)
-			pr_err("Failed to retrieve scheduler Rx interrupt\n");
+	if (ret && ret != -EOPNOTSUPP) {
+		pr_err("Failed to retrieve scheduler Rx interrupt\n");
 		return ret;
+	} else if (ret) {
+		ret = ffa_features(FFA_FEAT_NOTIFICATION_PENDING_INT, 0,
+				   &intr_id, NULL);
+		if (ret) {
+			if (ret != -EOPNOTSUPP)
+				pr_err("Failed to retrieve notification pending interrupt\n");
+			return ret;
+		}
+		*irq_is_npi = true;
 	}
 
 	if (acpi_disabled) {
@@ -1389,7 +1408,7 @@ static void ffa_uninit_pcpu_irq(void)
 	}
 }
 
-static int ffa_init_pcpu_irq(unsigned int irq)
+static int ffa_init_pcpu_irq(void)
 {
 	struct ffa_pcpu_irq __percpu *irq_pcpu;
 	int ret, cpu;
@@ -1403,9 +1422,15 @@ static int ffa_init_pcpu_irq(unsigned int irq)
 
 	drv_info->irq_pcpu = irq_pcpu;
 
-	ret = request_percpu_irq(irq, sri_handler, "ARM-FFA-SRI", irq_pcpu);
+	if (drv_info->irq_is_npi)
+		ret = request_percpu_irq(drv_info->sr_or_np_irq, npi_handler,
+					 "ARM-FFA-NPI", irq_pcpu);
+	else
+		ret = request_percpu_irq(drv_info->sr_or_np_irq, sri_handler,
+					 "ARM-FFA-SRI", irq_pcpu);
 	if (ret) {
-		pr_err("Error registering notification IRQ %d: %d\n", irq, ret);
+		pr_err("Error registering NPI/SRI IRQ %d: %d\n",
+		       drv_info->sr_or_np_irq, ret);
 		return ret;
 	}
 
@@ -1453,7 +1478,7 @@ static void ffa_notifications_setup(void)
 		drv_info->bitmap_created = true;
 	}
 
-	irq = ffa_sr_or_np_irq_map();
+	irq = ffa_sr_or_np_irq_map(&drv_info->irq_is_npi);
 	if (irq <= 0) {
 		ret = irq;
 		goto cleanup;
@@ -1461,7 +1486,7 @@ static void ffa_notifications_setup(void)
 
 	drv_info->sr_or_np_irq = irq;
 
-	ret = ffa_init_pcpu_irq(irq);
+	ret = ffa_init_pcpu_irq();
 	if (ret)
 		goto cleanup;
 

-- 
2.43.2