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/**************************************************************************/
/* */
/* Copyright (c) Microsoft Corporation. All rights reserved. */
/* */
/* This software is licensed under the Microsoft Software License */
/* Terms for Microsoft Azure RTOS. Full text of the license can be */
/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
/* and in the root directory of this software. */
/* */
/**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** LevelX Component */
/** */
/** NOR Flash */
/** */
/**************************************************************************/
/**************************************************************************/
#define LX_SOURCE_CODE
/* Disable ThreadX error checking. */
#ifndef LX_DISABLE_ERROR_CHECKING
#define LX_DISABLE_ERROR_CHECKING
#endif
/* Include necessary system files. */
#include "lx_api.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _lx_nor_flash_next_block_to_erase_find PORTABLE C */
/* 6.1.7 */
/* AUTHOR */
/* */
/* William E. Lamie, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function finds the next block to erase in the NOR flash. */
/* */
/* INPUT */
/* */
/* nor_flash NOR flash instance */
/* return_erase_block Returned block to erase */
/* return_erase_count Returned erase count of block */
/* return_mapped_sectors Returned number of mapped */
/* sectors */
/* return_obsolete_sectors Returned number of obsolete */
/* sectors */
/* */
/* OUTPUT */
/* */
/* return status */
/* */
/* CALLS */
/* */
/* _lx_nor_flash_driver_read Driver flash sector read */
/* _lx_nor_flash_system_error Internal system error handler */
/* */
/* CALLED BY */
/* */
/* Internal LevelX */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 William E. Lamie Initial Version 6.0 */
/* 09-30-2020 William E. Lamie Modified comment(s), */
/* resulting in version 6.1 */
/* 06-02-2021 Bhupendra Naphade Modified comment(s), */
/* resulting in version 6.1.7 */
/* */
/**************************************************************************/
UINT _lx_nor_flash_next_block_to_erase_find(LX_NOR_FLASH *nor_flash, ULONG *return_erase_block, ULONG *return_erase_count, ULONG *return_mapped_sectors, ULONG *return_obsolete_sectors)
{
ULONG *block_word_ptr;
ULONG *list_word_ptr;
ULONG list_word;
ULONG i, j;
ULONG mapped_sectors;
ULONG erase_count;
ULONG obsolete_sectors;
ULONG min_block_erase = 0;
ULONG min_block_erase_count;
ULONG min_block_obsolete_count = 0;
ULONG min_block_mapped_count = 0;
ULONG max_obsolete_sectors;
ULONG max_obsolete_block = 0;
ULONG max_obsolete_erase_count = 0;
ULONG max_obsolete_mapped_count = 0;
ULONG min_system_block_erase_count;
ULONG max_system_block_erase_count;
ULONG erase_count_threshold;
#ifndef LX_DIRECT_READ
UINT status;
#endif
/* Setup the block word pointer to the first word of the search block. */
block_word_ptr = nor_flash -> lx_nor_flash_base_address;
/* Initialize the minimum erase count. */
min_block_erase_count = LX_ALL_ONES;
/* Initialize the system minimum and maximum erase counts. */
min_system_block_erase_count = LX_ALL_ONES;
max_system_block_erase_count = 0;
/* Initialize the maximum obsolete sector count. */
max_obsolete_sectors = 0;
/* Calculate the erase count threshold. */
if (nor_flash -> lx_nor_flash_free_physical_sectors >= nor_flash -> lx_nor_flash_physical_sectors_per_block)
{
/* Calculate erase count threshold by adding constant to the current minimum. */
erase_count_threshold = nor_flash -> lx_nor_flash_minimum_erase_count + LX_NOR_FLASH_MAX_ERASE_COUNT_DELTA;
}
else
{
/* When the number of free sectors is low, simply pick the block that has the most number of obsolete sectors. */
erase_count_threshold = LX_ALL_ONES;
}
/* Loop through the blocks to attempt to find the mapped logical sector. */
for (i = 0; i < nor_flash -> lx_nor_flash_total_blocks; i++)
{
/* Read the erase count of this block. */
#ifdef LX_DIRECT_READ
/* Read the word directly. */
erase_count = *(block_word_ptr);
#else
status = _lx_nor_flash_driver_read(nor_flash, block_word_ptr, &erase_count, 1);
/* Check for an error from flash driver. Drivers should never return an error.. */
if (status)
{
/* Call system error handler. */
_lx_nor_flash_system_error(nor_flash, status);
/* Return the error. */
return(status);
}
#endif
/* Update the system minimum and maximum erase counts. */
if (erase_count < min_system_block_erase_count)
min_system_block_erase_count = erase_count;
if (erase_count > max_system_block_erase_count)
max_system_block_erase_count = erase_count;
/* Compute the number of obsolete and mapped sectors for this block. */
obsolete_sectors = 0;
mapped_sectors = 0;
/* Setup a pointer to the mapped list. */
list_word_ptr = block_word_ptr + nor_flash -> lx_nor_flash_block_physical_sector_mapping_offset;
/* Loop through the mapped list for this block. */
for (j = 0; j < nor_flash -> lx_nor_flash_physical_sectors_per_block; j++)
{
/* Read the current mapping entry. */
#ifdef LX_DIRECT_READ
/* Read the word directly. */
list_word = *(list_word_ptr);
#else
status = _lx_nor_flash_driver_read(nor_flash, list_word_ptr, &list_word, 1);
/* Check for an error from flash driver. Drivers should never return an error.. */
if (status)
{
/* Call system error handler. */
_lx_nor_flash_system_error(nor_flash, status);
/* Return the error. */
return(status);
}
#endif
/* Determine if the entry hasn't been used. */
if (list_word == LX_NOR_PHYSICAL_SECTOR_FREE)
{
/* Since allocations are done sequentially in the block, we know nothing
else exists after this point. */
break;
}
/* Is this entry obsolete? */
if ((list_word & LX_NOR_PHYSICAL_SECTOR_VALID) == 0)
{
/* Increment the number of obsolete sectors. */
obsolete_sectors++;
}
else
{
/* Increment the number of mapped sectors. */
mapped_sectors++;
}
/* Move the list pointer ahead. */
list_word_ptr++;
}
/* Determine if we have a block with a new maximum number of obsolete sectors. */
if ((obsolete_sectors > max_obsolete_sectors) && (erase_count <= erase_count_threshold))
{
/* Update the new maximum obsolete sectors and related information. */
max_obsolete_sectors = obsolete_sectors;
max_obsolete_block = i;
max_obsolete_erase_count = erase_count;
max_obsolete_mapped_count = mapped_sectors;
}
else if ((max_obsolete_sectors) && (obsolete_sectors == max_obsolete_sectors) && (erase_count <= erase_count_threshold))
{
/* Another block has the same number of obsolete sectors. Does this new block have a smaller erase
count? */
if (erase_count < max_obsolete_erase_count)
{
/* Yes, erase the block with the smaller erase count. */
max_obsolete_sectors = obsolete_sectors;
max_obsolete_block = i;
max_obsolete_erase_count = erase_count;
max_obsolete_mapped_count = mapped_sectors;
}
}
/* Determine if we have a new minimum erase count. */
if (erase_count < min_block_erase_count)
{
/* Update the new minimum erase count and related information. */
min_block_erase_count = erase_count;
min_block_erase = i;
min_block_obsolete_count = obsolete_sectors;
min_block_mapped_count = mapped_sectors;
}
/* Move to the next block. */
block_word_ptr = block_word_ptr + nor_flash -> lx_nor_flash_words_per_block;
}
/* Determine if we can erase the block with the most obsolete sectors. */
if (max_obsolete_sectors)
{
/* Erase the block with the most obsolete sectors. */
*return_erase_block = max_obsolete_block;
*return_erase_count = max_obsolete_erase_count;
*return_obsolete_sectors = max_obsolete_sectors;
*return_mapped_sectors = max_obsolete_mapped_count;
}
else
{
/* Otherwise, choose the block with the smallest erase count. */
*return_erase_block = min_block_erase;
*return_erase_count = min_block_erase_count;
*return_obsolete_sectors = min_block_obsolete_count;
*return_mapped_sectors = min_block_mapped_count;
}
/* Update the overall minimum and maximum erase count. */
nor_flash -> lx_nor_flash_minimum_erase_count = min_system_block_erase_count;
nor_flash -> lx_nor_flash_maximum_erase_count = max_system_block_erase_count;
/* Return success. */
return(LX_SUCCESS);
}