Merge branch 'feature/dualcore_spi_flash_api' into 'master'

Dual core compatible spi flash APIs

Implementation of spi flash APIs which work in dual core mode.

This also includes other changes:
- fixes to FreeRTOS tasks.c made by Jeroen and me — these were originally made to fix issues with high priority tasks seen in WiFi stack, but were required to get stuff in ipc.c working as well
- initial base idea with two high-priority tasks was separated into a separate API — esp_ipc.h. That API allows one to run a function on the other CPU from a high-priority task. Because we don't have preemption across CPUs, this is currently not very fast: it requires on average half a tick until the second CPU switches to the high priority task. Currently that API can be either blocking, or non-blocking with queue length of 1. I haven't yet found a use case for arbitrary sized queue of IPC requests. Anyone who needs that can trivially add that later by replacing a binary semaphore with a generic queue.

With these changes i can run application with WiFi stack and NVS on both cores.

See merge request !25

components/esp32/include/esp_err.h

@@ -27,7 +27,10 @@ typedef int32_t esp_err_t;
 #define ESP_OK          0
 #define ESP_FAIL        -1
 
-#define ESP_ERR_NO_MEM  0x101
+#define ESP_ERR_NO_MEM          0x101
+#define ESP_ERR_INVALID_ARG     0x102
+#define ESP_ERR_INVALID_STATE   0x103
+
 
 #ifdef __cplusplus
 }

components/esp32/include/esp_ipc.h

@@ -0,0 +1,88 @@
+// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed 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 __ESP_IPC_H__
+#define __ESP_IPC_H__
+
+#include <esp_err.h>
+
+typedef void (*esp_ipc_func_t)(void* arg);
+
+/**
+ * @brief Inter-processor call APIs
+ *
+ * FreeRTOS provides several APIs which can be used to communicate between
+ * different tasks, including tasks running on different CPUs.
+ * This module provides additional APIs to run some code on the other CPU.
+ *
+ * These APIs can only be used when FreeRTOS scheduler is running.
+ */
+
+
+/**
+ * @brief Initialize inter-processor call module.
+ *
+ * This function start two tasks, one on each CPU. These tasks are started
+ * with high priority. These tasks are normally inactive, waiting until one of
+ * the esp_ipc_call_* functions to be used. One of these tasks will be
+ * woken up to execute the callback provided to esp_ipc_call_nonblocking or
+ * esp_ipc_call_blocking.
+ */
+void esp_ipc_init();
+
+
+/**
+ * @brief Execute function on the given CPU
+ *
+ * This will wake a high-priority task on CPU indicated by cpu_id argument,
+ * and run func(arg) in the context of that task.
+ * This function returns as soon as the high-priority task is woken up.
+ * If another IPC call is already being executed, this function will also wait
+ * for it to complete.
+ *
+ * In single-core mode, returns ESP_ERR_INVALID_ARG for cpu_id 1.
+ *
+ * @param cpu_id CPU where function should be executed (0 or 1)
+ * @param func pointer to a function which should be executed
+ * @param arg arbitrary argument to be passed into function
+ *
+ * @return ESP_ERR_INVALID_ARG if cpu_id is invalid
+ *         ESP_ERR_INVALID_STATE if FreeRTOS scheduler is not running
+ *         ESP_OK otherwise
+ */
+esp_err_t esp_ipc_call(uint32_t cpu_id, esp_ipc_func_t func, void* arg);
+
+
+/**
+ * @brief Execute function on the given CPU and wait for it to finish
+ *
+ * This will wake a high-priority task on CPU indicated by cpu_id argument,
+ * and run func(arg) in the context of that task.
+ * This function waits for func to return.
+ *
+ * In single-core mode, returns ESP_ERR_INVALID_ARG for cpu_id 1.
+ *
+ * @param cpu_id CPU where function should be executed (0 or 1)
+ * @param func pointer to a function which should be executed
+ * @param arg arbitrary argument to be passed into function
+ *
+ * @return ESP_ERR_INVALID_ARG if cpu_id is invalid
+ *         ESP_ERR_INVALID_STATE if FreeRTOS scheduler is not running
+ *         ESP_OK otherwise
+ */
+esp_err_t esp_ipc_call_blocking(uint32_t cpu_id, esp_ipc_func_t func, void* arg);
+
+
+
+#endif /* __ESP_IPC_H__ */