boards/arm/stm32f7/nucleo-144/src/stm32_dma_alloc.c

/****************************************************************************
 * boards/arm/stm32f7/nucleo-144/src/stm32_dma_alloc.c
 *
 *   Copyright (C) 2016 PX4 Development Team. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name PX4 nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>
#include <syslog.h>
#include <stdint.h>
#include <errno.h>
#include <nuttx/mm/gran.h>

#include "nucleo-144.h"

#if defined(CONFIG_FAT_DMAMEMORY)

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

#if !defined(CONFIG_GRAN)
#  error microSD DMA support requires CONFIG_GRAN
#endif

#define BOARD_DMA_ALLOC_POOL_SIZE (8*512)

/****************************************************************************
 * Private Data
 ****************************************************************************/

static GRAN_HANDLE dma_allocator;

/* The DMA heap size constrains the total number of things that can be
 * ready to do DMA at a time.
 *
 * For example, FAT DMA depends on one sector-sized buffer per filesystem
 * plus one sector-sized buffer per file.
 *
 * We use a fundamental alignment / granule size of 64B; this is sufficient
 * to guarantee alignment for the largest STM32 DMA burst
 * (16 beats x 32bits).
 */

static
uint8_t g_dma_heap[BOARD_DMA_ALLOC_POOL_SIZE] aligned_data(64);

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: stm32_dma_alloc_init
 *
 * Description:
 *   All boards may optionally provide this API to instantiate a pool of
 *   memory for uses with FAST FS DMA operations.
 *
 ****************************************************************************/

int stm32_dma_alloc_init(void)
{
  dma_allocator = gran_initialize(g_dma_heap,
                                  sizeof(g_dma_heap),
                                  7,  /* 128B granule - must be > alignment (XXX bug?) */
                                  6); /* 64B alignment */

  if (dma_allocator == NULL)
    {
      return -ENOMEM;
    }

  return OK;
}

/* DMA-aware allocator stubs for the FAT filesystem. */

void *fat_dma_alloc(size_t size)
{
  return gran_alloc(dma_allocator, size);
}

void fat_dma_free(void *memory, size_t size)
{
  gran_free(dma_allocator, memory, size);
}

#endif /* CONFIG_FAT_DMAMEMORY */