firmware: arm_ffa: Implement notification bitmap create and destroy interfaces

On systems without a hypervisor the responsibility of requesting the
creation of the notification bitmaps in the SPM falls to the FF-A driver.

We use FFA features to determine if the ABI is supported, if it is not
we can assume there is a hypervisor present and will take care of ensure
the relevant notifications bitmaps are created on this partitions behalf.

An endpoint’s notification bitmaps needs to be setup before it configures
its notifications and before other endpoints and partition managers can
start signaling these notifications.

Add interface to create and destroy the notification bitmaps and use the
same to do the necessary setup during the initialisation and cleanup
during the module exit.

Link: https://lore.kernel.org/r/20231005-ffa_v1-1_notif-v4-2-cddd3237809c@arm.comSigned-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_ffa/driver.c

@@ -84,6 +84,7 @@ struct ffa_drv_info {
 	void *rx_buffer;
 	void *tx_buffer;
 	bool mem_ops_native;
+	bool bitmap_created;
 };
 
 static struct ffa_drv_info *drv_info;
@@ -555,6 +556,37 @@ static int ffa_features(u32 func_feat_id, u32 input_props,
 	return 0;
 }
 
+static int ffa_notification_bitmap_create(void)
+{
+	ffa_value_t ret;
+	u16 vcpu_count = nr_cpu_ids;
+
+	invoke_ffa_fn((ffa_value_t){
+		      .a0 = FFA_NOTIFICATION_BITMAP_CREATE,
+		      .a1 = drv_info->vm_id, .a2 = vcpu_count,
+		      }, &ret);
+
+	if (ret.a0 == FFA_ERROR)
+		return ffa_to_linux_errno((int)ret.a2);
+
+	return 0;
+}
+
+static int ffa_notification_bitmap_destroy(void)
+{
+	ffa_value_t ret;
+
+	invoke_ffa_fn((ffa_value_t){
+		      .a0 = FFA_NOTIFICATION_BITMAP_DESTROY,
+		      .a1 = drv_info->vm_id,
+		      }, &ret);
+
+	if (ret.a0 == FFA_ERROR)
+		return ffa_to_linux_errno((int)ret.a2);
+
+	return 0;
+}
+
 static void ffa_set_up_mem_ops_native_flag(void)
 {
 	if (!ffa_features(FFA_FN_NATIVE(MEM_LEND), 0, NULL, NULL) ||
@@ -704,6 +736,34 @@ static void ffa_setup_partitions(void)
 	kfree(pbuf);
 }
 
+static int ffa_notifications_setup(void)
+{
+	int ret;
+
+	ret = ffa_features(FFA_NOTIFICATION_BITMAP_CREATE, 0, NULL, NULL);
+	if (ret) {
+		pr_err("Notifications not supported, continuing with it ..\n");
+		return 0;
+	}
+
+	ret = ffa_notification_bitmap_create();
+	if (ret) {
+		pr_err("notification_bitmap_create error %d\n", ret);
+		return ret;
+	}
+	drv_info->bitmap_created = true;
+
+	return 0;
+}
+
+static void ffa_notifications_cleanup(void)
+{
+	if (drv_info->bitmap_created) {
+		ffa_notification_bitmap_destroy();
+		drv_info->bitmap_created = false;
+	}
+}
+
 static int __init ffa_init(void)
 {
 	int ret;
@@ -759,7 +819,7 @@ static int __init ffa_init(void)
 
 	ffa_set_up_mem_ops_native_flag();
 
-	return 0;
+	return ffa_notifications_setup();
 free_pages:
 	if (drv_info->tx_buffer)
 		free_pages_exact(drv_info->tx_buffer, RXTX_BUFFER_SIZE);
@@ -774,6 +834,7 @@ subsys_initcall(ffa_init);
 
 static void __exit ffa_exit(void)
 {
+	ffa_notifications_cleanup();
 	ffa_rxtx_unmap(drv_info->vm_id);
 	free_pages_exact(drv_info->tx_buffer, RXTX_BUFFER_SIZE);
 	free_pages_exact(drv_info->rx_buffer, RXTX_BUFFER_SIZE);