firmware: arm_ffa: Add support for handling notification pending interrupt(NPI)

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. Both SRI and NPI can be
supported simultaneously.

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.
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Link: https://lore.kernel.org/r/20240411-ffa_npi_support-v2-3-927a670254e6@arm.comSigned-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_ffa/driver.c

@@ -101,6 +101,7 @@ struct ffa_drv_info {
 	bool bitmap_created;
 	bool notif_enabled;
 	unsigned int sched_recv_irq;
+	unsigned int notif_pend_irq;
 	unsigned int cpuhp_state;
 	struct ffa_pcpu_irq __percpu *irq_pcpu;
 	struct workqueue_struct *notif_pcpu_wq;
@@ -1301,6 +1302,15 @@ static irqreturn_t ffa_sched_recv_irq_handler(int irq, void *irq_data)
 	return IRQ_HANDLED;
 }
 
+static irqreturn_t notif_pend_irq_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 void ffa_sched_recv_irq_work_fn(struct work_struct *work)
 {
 	ffa_notification_info_get();
@@ -1364,13 +1374,19 @@ static void ffa_irq_unmap(unsigned int irq)
 
 static int ffa_cpuhp_pcpu_irq_enable(unsigned int cpu)
 {
+	if (drv_info->sched_recv_irq)
 		enable_percpu_irq(drv_info->sched_recv_irq, IRQ_TYPE_NONE);
+	if (drv_info->notif_pend_irq)
+		enable_percpu_irq(drv_info->notif_pend_irq, IRQ_TYPE_NONE);
 	return 0;
 }
 
 static int ffa_cpuhp_pcpu_irq_disable(unsigned int cpu)
 {
+	if (drv_info->sched_recv_irq)
 		disable_percpu_irq(drv_info->sched_recv_irq);
+	if (drv_info->notif_pend_irq)
+		disable_percpu_irq(drv_info->notif_pend_irq);
 	return 0;
 }
 
@@ -1389,13 +1405,16 @@ static void ffa_uninit_pcpu_irq(void)
 	if (drv_info->sched_recv_irq)
 		free_percpu_irq(drv_info->sched_recv_irq, drv_info->irq_pcpu);
 
+	if (drv_info->notif_pend_irq)
+		free_percpu_irq(drv_info->notif_pend_irq, drv_info->irq_pcpu);
+
 	if (drv_info->irq_pcpu) {
 		free_percpu(drv_info->irq_pcpu);
 		drv_info->irq_pcpu = NULL;
 	}
 }
 
-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;
@@ -1409,12 +1428,27 @@ static int ffa_init_pcpu_irq(unsigned int irq)
 
 	drv_info->irq_pcpu = irq_pcpu;
 
-	ret = request_percpu_irq(irq, ffa_sched_recv_irq_handler, "ARM-FFA-SRI",
-				 irq_pcpu);
+	if (drv_info->sched_recv_irq) {
+		ret = request_percpu_irq(drv_info->sched_recv_irq,
+					 ffa_sched_recv_irq_handler,
+					 "ARM-FFA-SRI", irq_pcpu);
+		if (ret) {
+			pr_err("Error registering percpu SRI nIRQ %d : %d\n",
+			       drv_info->sched_recv_irq, ret);
+			return ret;
+		}
+	}
+
+	if (drv_info->notif_pend_irq) {
+		ret = request_percpu_irq(drv_info->notif_pend_irq,
+					 notif_pend_irq_handler,
+					 "ARM-FFA-NPI", irq_pcpu);
 		if (ret) {
-		pr_err("Error registering notification IRQ %d: %d\n", irq, ret);
+			pr_err("Error registering percpu NPI nIRQ %d : %d\n",
+			       drv_info->notif_pend_irq, ret);
 			return ret;
 		}
+	}
 
 	INIT_WORK(&drv_info->sched_recv_irq_work, ffa_sched_recv_irq_work_fn);
 	INIT_WORK(&drv_info->notif_pcpu_work, notif_pcpu_irq_work_fn);
@@ -1438,6 +1472,8 @@ static void ffa_notifications_cleanup(void)
 	ffa_uninit_pcpu_irq();
 	ffa_irq_unmap(drv_info->sched_recv_irq);
 	drv_info->sched_recv_irq = 0;
+	ffa_irq_unmap(drv_info->notif_pend_irq);
+	drv_info->notif_pend_irq = 0;
 
 	if (drv_info->bitmap_created) {
 		ffa_notification_bitmap_destroy();
@@ -1448,7 +1484,7 @@ static void ffa_notifications_cleanup(void)
 
 static void ffa_notifications_setup(void)
 {
-	int ret, irq;
+	int ret;
 
 	ret = ffa_features(FFA_NOTIFICATION_BITMAP_CREATE, 0, NULL, NULL);
 	if (!ret) {
@@ -1461,15 +1497,18 @@ static void ffa_notifications_setup(void)
 		drv_info->bitmap_created = true;
 	}
 
-	irq = ffa_irq_map(FFA_FEAT_SCHEDULE_RECEIVER_INT);
-	if (irq <= 0) {
-		ret = irq;
-		goto cleanup;
-	}
+	ret = ffa_irq_map(FFA_FEAT_SCHEDULE_RECEIVER_INT);
+	if (ret > 0)
+		drv_info->sched_recv_irq = ret;
 
-	drv_info->sched_recv_irq = irq;
+	ret = ffa_irq_map(FFA_FEAT_NOTIFICATION_PENDING_INT);
+	if (ret > 0)
+		drv_info->notif_pend_irq = ret;
+
+	if (!drv_info->sched_recv_irq && !drv_info->notif_pend_irq)
+		goto cleanup;
 
-	ret = ffa_init_pcpu_irq(irq);
+	ret = ffa_init_pcpu_irq();
 	if (ret)
 		goto cleanup;