/****************************************************************************
 * include/nuttx/mm/gran.h
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * 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 __INCLUDE_NUTTX_MM_GRAN_H
#define __INCLUDE_NUTTX_MM_GRAN_H

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

#include <nuttx/config.h>

#include <sys/types.h>
#include <stdint.h>

#ifdef CONFIG_GRAN

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

/* Configuration ************************************************************/

/* CONFIG_GRAN - Enable granule allocator support
 * CONFIG_GRAN_INTR - Normally mutual exclusive access to granule allocator
 *   data is assured using a semaphore.  If this option is set then, instead,
 *   mutual exclusion logic will disable interrupts.  While this options is
 *   more invasive to system performance, it will also support use of the
 *   granule allocator from interrupt level logic.
 * CONFIG_DEBUG_GRAN - Just like CONFIG_DEBUG_MM, but only generates output
 *   from the gran allocation logic.
 */

/****************************************************************************
 * Public Types
 ****************************************************************************/

/* An opaque reference to an instance of a granule allocator state */

typedef FAR void *GRAN_HANDLE;

/* Form in which the state of the granule allocator is returned */

struct graninfo_s
{
  uint8_t   log2gran;  /* Log base 2 of the size of one granule */
  uint16_t  ngranules; /* The total number of (aligned) granules in the heap */
  uint16_t  nfree;     /* The number of free granules */
  uint16_t  mxfree;    /* The longest sequence of free granules */
};

/****************************************************************************
 * Public Function Prototypes
 ****************************************************************************/

#ifdef __cplusplus
#define EXTERN extern "C"
extern "C"
{
#else
#define EXTERN extern
#endif

/****************************************************************************
 * Name: gran_initialize
 *
 * Description:
 *   Set up one granule allocator instance.  Allocations will be aligned to
 *   the alignment size (log2align; allocations will be in units of the
 *   granule size (log2gran). Larger granules will give better performance
 *   and less overhead but more losses of memory due to quantization waste.
 *   Additional memory waste can occur from alignment; log2align should be
 *   set to 0 unless you are using the granule allocator to manage DMA
 *   or page-aligned memory and your hardware has specific memory alignment
 *   requirements.
 *
 *   General Usage Summary.  This is an example using the GCC section
 *   attribute to position a DMA heap in memory (logic in the linker script
 *   would assign the section .dmaheap to the DMA memory.
 *
 *   FAR uint32_t g_dmaheap[DMAHEAP_SIZE] locate_data(.dmaheap);
 *
 *   The heap is created by calling gran_initialize.  Here the granule size
 *   is set to 64 bytes and the alignment to 16 bytes:
 *
 *     GRAN_HANDLE handle = gran_initialize(g_dmaheap, DMAHEAP_SIZE, 6, 4);
 *
 *   Then the GRAN_HANDLE can be used to allocate memory:
 *
 *     FAR uint8_t *dma_memory = (FAR uint8_t *)gran_alloc(handle, 47);
 *
 *   The actual memory allocates will be 64 byte (wasting 17 bytes) and
 *   will be aligned at least to (1 << log2align).
 *
 *   NOTE: The current implementation also restricts the maximum allocation
 *   size to 32 granules.  That restriction could be eliminated with some
 *   additional coding effort.
 *
 * Input Parameters:
 *   heapstart - Start of the granule allocation heap
 *   heapsize  - Size of heap in bytes
 *   log2gran  - Log base 2 of the size of one granule.  0->1 byte,
 *               1->2 bytes, 2->4 bytes, 3->8 bytes, etc.
 *   log2align - Log base 2 of required alignment.  0->1 byte,
 *               1->2 bytes, 2->4 bytes, 3->8 bytes, etc.  Note that
 *               log2gran must be greater than or equal to log2align
 *               so that all contiguous granules in memory will meet
 *               the minimum alignment requirement. A value of zero
 *               would mean that no alignment is required.
 *
 * Returned Value:
 *   On success, a non-NULL handle is returned that may be used with other
 *   granule allocator interfaces.
 *
 ****************************************************************************/

GRAN_HANDLE gran_initialize(FAR void *heapstart, size_t heapsize,
                            uint8_t log2gran, uint8_t log2align);

/****************************************************************************
 * Name: gran_release
 *
 * Description:
 *   Uninitialize a gram memory allocator and release resources held by the
 *   allocator.
 *
 * Input Parameters:
 *   handle - The handle previously returned by gran_initialize
 *
 * Returned Value:
 *   None.
 *
 ****************************************************************************/

void gran_release(GRAN_HANDLE handle);

/****************************************************************************
 * Name: gran_reserve
 *
 * Description:
 *   Reserve memory in the granule heap.  This will reserve the granules
 *   that contain the start and end addresses plus all of the granules
 *   in between.  This should be done early in the initialization sequence
 *   before any other allocations are made.
 *
 *   Reserved memory can never be allocated (it can be freed however which
 *   essentially unreserves the memory).
 *
 * Input Parameters:
 *   handle - The handle previously returned by gran_initialize
 *   start  - The address of the beginning of the region to be reserved.
 *   size   - The size of the region to be reserved
 *
 * Returned Value:
 *   On success, a non-NULL pointer to the allocated memory is returned;
 *   NULL is returned on failure.
 *
 ****************************************************************************/

FAR void *gran_reserve(GRAN_HANDLE handle, uintptr_t start, size_t size);

/****************************************************************************
 * Name: gran_alloc
 *
 * Description:
 *   Allocate memory from the granule heap.
 *
 *   NOTE: The current implementation also restricts the maximum allocation
 *   size to 32 granules.  That restriction could be eliminated with some
 *   additional coding effort.
 *
 * Input Parameters:
 *   handle - The handle previously returned by gran_initialize
 *   size   - The size of the memory region to allocate.
 *
 * Returned Value:
 *   On success, a non-NULL pointer to the allocated memory is returned;
 *   NULL is returned on failure.
 *
 ****************************************************************************/

FAR void *gran_alloc(GRAN_HANDLE handle, size_t size);

/****************************************************************************
 * Name: gran_alloc_align
 *
 * Description:
 *   Allocate memory from the granule heap.
 *
 *   NOTE: The current implementation also restricts the maximum allocation
 *   size to 32 granules.  That restriction could be eliminated with some
 *   additional coding effort.
 *
 * Input Parameters:
 *   handle - The handle previously returned by gran_initialize
 *   size   - The size of the memory region to allocate.
 *   align  - The size of the memory region to align.
 *
 * Returned Value:
 *   On success, a non-NULL pointer to the allocated memory is returned;
 *   NULL is returned on failure.
 *
 ****************************************************************************/

FAR void *gran_alloc_align(GRAN_HANDLE handle, size_t size, size_t align);

/****************************************************************************
 * Name: gran_free
 *
 * Description:
 *   Return memory to the granule heap.
 *
 * Input Parameters:
 *   handle - The handle previously returned by gran_initialize
 *   memory - A pointer to memory previously allocated by gran_alloc.
 *
 * Returned Value:
 *   None
 *
 ****************************************************************************/

void gran_free(GRAN_HANDLE handle, FAR void *memory, size_t size);

/****************************************************************************
 * Name: gran_info
 *
 * Description:
 *   Return information about the granule heap.
 *
 * Input Parameters:
 *   handle - The handle previously returned by gran_initialize
 *   info   - Memory location to return the gran allocator info.
 *
 * Returned Value:
 *   Zero (OK) is returned on success; a negated errno value is return on
 *   any failure.
 *
 ****************************************************************************/

void gran_info(GRAN_HANDLE handle, FAR struct graninfo_s *info);

#undef EXTERN
#ifdef __cplusplus
}
#endif

#endif /* CONFIG_GRAN */
#endif /* __INCLUDE_NUTTX_MM_GRAN_H */
