porting: Add convenience init function in FreeRTOS NPL

This adds convenience function for FreeRTOS NPL which initializes
OS-specific things. Currently it creates tasks necessary to run ported
NimBLE.

porting/npl/freertos/include/nimble/nimble_port_freertos.h

@@ -0,0 +1,35 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef _NIMBLE_PORT_FREERTOS_H
+#define _NIMBLE_PORT_FREERTOS_H
+
+#include "nimble/nimble_npl.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void nimble_port_freertos_init(TaskFunction_t host_task_fn);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _NIMBLE_PORT_FREERTOS_H */

porting/npl/freertos/src/nimble_port_freertos.c

@@ -0,0 +1,51 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include <stddef.h>
+#include "FreeRTOS.h"
+#include "task.h"
+#include "nimble/nimble_port.h"
+
+#if NIMBLE_CFG_CONTROLLER
+static TaskHandle_t ll_task_h;
+#endif
+static TaskHandle_t host_task_h;
+
+void
+nimble_port_freertos_init(TaskFunction_t host_task_fn)
+{
+#if NIMBLE_CFG_CONTROLLER
+    /*
+     * Create task where NimBLE LL will run. This one is required as LL has its
+     * own event queue and should have highest priority. The task function is
+     * provided by NimBLE and in case of FreeRTOS it does not need to be wrapped
+     * since it has compatible prototype.
+     */
+    xTaskCreate(nimble_port_ll_task_func, "ll", configMINIMAL_STACK_SIZE + 400,
+                NULL, configMAX_PRIORITIES - 1, &ll_task_h);
+#endif
+
+    /*
+     * Create task where NimBLE host will run. It is not strictly necessary to
+     * have separate task for NimBLE host, but since something needs to handle
+     * default queue it is just easier to make separate task which does this.
+     */
+    xTaskCreate(host_task_fn, "ble", configMINIMAL_STACK_SIZE + 400,
+                NULL, tskIDLE_PRIORITY + 1, &host_task_h);
+}