esp-idf/components/esp32s2/include/esp_spiram.h

// Copyright 2015-2017 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_SPIRAM_H
#define __ESP_SPIRAM_H

#include <stddef.h>
#include <stdint.h>
#include "esp_err.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @brief Initialize spiram interface/hardware. Normally called from cpu_start.c.
 *
 * @return ESP_OK on success
 */
esp_err_t esp_spiram_init(void);

/**
 * @brief Configure Cache/MMU for access to external SPI RAM.
 *
 * Normally this function is called from cpu_start, if CONFIG_SPIRAM_BOOT_INIT
 * option is enabled. Applications which need to enable SPI RAM at run time
 * can disable CONFIG_SPIRAM_BOOT_INIT, and call this function later.
 *
 * @attention this function must be called with flash cache disabled.
 */
void esp_spiram_init_cache(void);


/**
 * @brief Memory test for SPI RAM. Should be called after SPI RAM is initialized and
 * (in case of a dual-core system) the app CPU is online. This test overwrites the 
 * memory with crap, so do not call after e.g. the heap allocator has stored important
 * stuff in SPI RAM.
 *
 * @return true on success, false on failed memory test
 */
bool esp_spiram_test(void);


/**
 * @brief Add the initialized SPI RAM to the heap allocator.
 */
esp_err_t esp_spiram_add_to_heapalloc(void);


/**
 * @brief Get the size of the attached SPI RAM chip selected in menuconfig
 *
 * @return Size in bytes, or 0 if no external RAM chip support compiled in.
 */
size_t esp_spiram_get_size(void);


/**
 * @brief Force a writeback of the data in the SPI RAM cache. This is to be called whenever
 * cache is disabled, because disabling cache on the ESP32 discards the data in the SPI
 * RAM cache.
 *
 * This is meant for use from within the SPI flash code.
 */
void esp_spiram_writeback_cache(void);



/**
 * @brief Reserve a pool of internal memory for specific DMA/internal allocations
 *
 * @param size Size of reserved pool in bytes
 *
 * @return
 *          - ESP_OK on success
 *          - ESP_ERR_NO_MEM when no memory available for pool
 */
esp_err_t esp_spiram_reserve_dma_pool(size_t size);

#ifdef __cplusplus
}
#endif

#endif