768 lines
30 KiB
C
768 lines
30 KiB
C
// Copyright 2022 Nick Brassel (@tzarc)
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// SPDX-License-Identifier: GPL-2.0-or-later
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#include <stdbool.h>
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#include "fnv.h"
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#include "wear_leveling.h"
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#include "wear_leveling_internal.h"
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/*
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This wear leveling algorithm is adapted from algorithms from previous
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implementations in QMK, namely:
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- Artur F. (http://engsta.com/stm32-flash-memory-eeprom-emulator/)
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- Yiancar -- QMK's base implementation for STM32F303
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- Ilya Zhuravlev -- initial wear leveling algorithm
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- Don Kjer -- increased flash density algorithm
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- Nick Brassel (@tzarc) -- decoupled for use on other peripherals
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At this layer, it is assumed that any reads/writes from the backing store
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have a "reset state" after erasure of zero.
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It is up to the backing store to perform translation of values, such as
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taking the complement in order to deal with flash memory's reset value.
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Terminology:
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- Backing store: this is the storage area used by the wear leveling
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algorithm.
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- Backing size: this is the amount of storage provided by the backing
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store for use by the wear leveling algorithm.
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- Backing write size: this is the minimum number of bytes the backing
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store can write in a single operation.
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- Logical data: this is the externally-visible "emulated EEPROM" that
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external subsystems "see" when performing reads/writes.
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- Logical size: this is the amount of storage available for use
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externally. Effectively, the "size of the EEPROM".
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- Write log: this is a section of the backing store used to keep track
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of modifications without overwriting existing data. This log is
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"played back" on startup such that any subsequent reads are capable
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of returning the latest data.
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- Consolidated data: this is a section of the backing store reserved for
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use for the latest copy of logical data. This is only ever written
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when the write log is full -- the latest values for the logical data
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are written here and the write log is cleared.
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Configurables:
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- BACKING_STORE_WRITE_SIZE: The number of bytes requires for a write
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operation. This is defined by the capabilities of the backing store.
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- WEAR_LEVELING_BACKING_SIZE: The number of bytes provided by the
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backing store for use by the wear leveling algorithm. This is
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defined by the capabilities of the backing store. This value must
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also be at least twice the size of the logical size, as well as a
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multiple of the logical size.
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- WEAR_LEVELING_LOGICAL_SIZE: The number of bytes externally visible
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to other subsystems performing reads/writes. This must be a multiple
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of the write size.
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General algorithm:
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During initialization:
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* The contents of the consolidated data section are read into cache.
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* The contents of the write log are "played back" and update the
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cache accordingly.
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During reads:
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* Logical data is served from the cache.
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During writes:
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* The cache is updated with the new data.
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* A new write log entry is appended to the log.
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* If the log's full, data is consolidated and the write log cleared.
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Write log structure:
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The first 8 bytes of the write log are a FNV1a_64 hash of the contents
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of the consolidated data area, in an attempt to detect and guard against
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any data corruption.
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The write log follows the hash:
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Given that the algorithm needs to cater for 2-, 4-, and 8-byte writes,
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a variable-length write log entry is used such that the minimal amount
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of storage is used based off the backing store write size.
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Firstly, an empty log entry is expected to be all zeros. If the backing
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store uses 0xFF for cleared bytes, it should return the complement, such
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that this wear-leveling algorithm "receives" zeros.
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For multi-byte writes, up to 8 bytes will be used for each log entry,
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depending on the size of backing store writes:
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╔ Multi-byte Log Entry (2, 4-byte) ═╗
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║00XXXYYY║YYYYYYYY║YYYYYYYY║AAAAAAAA║
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║ └┬┘└┬┘║└──┬───┘║└──┬───┘║└──┬───┘║
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║ LenAdd║ Address║ Address║Value[0]║
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╚════════╩════════╩════════╩════════╝
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╔ Multi-byte Log Entry (2-byte) ══════════════════════╗
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║00XXXYYY║YYYYYYYY║YYYYYYYY║AAAAAAAA║BBBBBBBB║CCCCCCCC║
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║ └┬┘└┬┘║└──┬───┘║└──┬───┘║└──┬───┘║└──┬───┘║└──┬───┘║
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║ LenAdd║ Address║ Address║Value[0]║Value[1]║Value[2]║
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╚════════╩════════╩════════╩════════╩════════╩════════╝
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╔ Multi-byte Log Entry (2, 4, 8-byte) ══════════════════════════════════╗
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║00XXXYYY║YYYYYYYY║YYYYYYYY║AAAAAAAA║BBBBBBBB║CCCCCCCC║DDDDDDDD║EEEEEEEE║
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║ └┬┘└┬┘║└──┬───┘║└──┬───┘║└──┬───┘║└──┬───┘║└──┬───┘║└──┬───┘║└──┬───┘║
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║ LenAdd║ Address║ Address║Value[0]║Value[1]║Value[2]║Value[3]║Value[4]║
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╚════════╩════════╩════════╩════════╩════════╩════════╩════════╩════════╝
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19 bits are used for the address, which allows for a max logical size of
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512kB. Up to 5 bytes can be included in a single log entry.
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For 2-byte backing store writes, the last two bytes are optional
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depending on the length of data to be written. Accordingly, either 3
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or 4 backing store write operations will occur.
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For 4-byte backing store writes, either one or two write operations
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occur, depending on the length.
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For 8-byte backing store writes, one write operation occur.
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2-byte backing store optimizations:
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For single byte writes, addresses between 0...63 are encoded in a single
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backing store write operation. 4- and 8-byte backing stores do not have
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this optimization as it does not minimize the number of bytes written.
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╔ Byte-Entry ════╗
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║01XXXXXXYYYYYYYY║
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║ └─┬──┘└──┬───┘║
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║ Address Value ║
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╚════════════════╝
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0 <= Address < 0x40 (64)
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A second optimization takes into account uint16_t writes of 0 or 1,
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specifically catering for KC_NO and KC_TRANSPARENT in the dynamic keymap
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subsystem. This is valid only for the first 16kB of logical data --
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addresses outside this range will use the multi-byte encoding above.
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╔ U16-Encoded 0 ═╗
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║100XXXXXXXXXXXXX║
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║ │└─────┬─────┘║
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║ │Address >> 1 ║
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║ └── Value: 0 ║
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╚════════════════╝
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0 <= Address <= 0x3FFE (16382)
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╔ U16-Encoded 1 ═╗
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║101XXXXXXXXXXXXX║
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║ │└─────┬─────┘║
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║ │Address >> 1 ║
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║ └── Value: 1 ║
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╚════════════════╝
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0 <= Address <= 0x3FFE (16382) */
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/**
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* Storage area for the wear-leveling cache.
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*/
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static struct __attribute__((__aligned__(BACKING_STORE_WRITE_SIZE))) {
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__attribute__((__aligned__(BACKING_STORE_WRITE_SIZE))) uint8_t cache[(WEAR_LEVELING_LOGICAL_SIZE)];
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uint32_t write_address;
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bool unlocked;
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} wear_leveling;
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/**
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* Locking helper: status
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*/
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typedef enum backing_store_lock_status_t { STATUS_FAILURE = 0, STATUS_SUCCESS, STATUS_UNCHANGED } backing_store_lock_status_t;
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/**
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* Locking helper: unlock
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*/
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static inline backing_store_lock_status_t wear_leveling_unlock(void) {
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if (wear_leveling.unlocked) {
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return STATUS_UNCHANGED;
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}
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if (!backing_store_unlock()) {
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return STATUS_FAILURE;
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}
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wear_leveling.unlocked = true;
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return STATUS_SUCCESS;
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}
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/**
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* Locking helper: lock
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*/
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static inline backing_store_lock_status_t wear_leveling_lock(void) {
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if (!wear_leveling.unlocked) {
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return STATUS_UNCHANGED;
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}
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if (!backing_store_lock()) {
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return STATUS_FAILURE;
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}
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wear_leveling.unlocked = false;
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return STATUS_SUCCESS;
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}
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/**
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* Resets the cache, ensuring the write address is correctly initialised.
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*/
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static void wear_leveling_clear_cache(void) {
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memset(wear_leveling.cache, 0, (WEAR_LEVELING_LOGICAL_SIZE));
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wear_leveling.write_address = (WEAR_LEVELING_LOGICAL_SIZE) + 8; // +8 is due to the FNV1a_64 of the consolidated buffer
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}
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/**
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* Reads the consolidated data from the backing store into the cache.
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* Does not consider the write log.
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*/
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static wear_leveling_status_t wear_leveling_read_consolidated(void) {
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wl_dprintf("Reading consolidated data\n");
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wear_leveling_status_t status = WEAR_LEVELING_SUCCESS;
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if (!backing_store_read_bulk(0, (backing_store_int_t *)wear_leveling.cache, sizeof(wear_leveling.cache) / sizeof(backing_store_int_t))) {
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wl_dprintf("Failed to read from backing store\n");
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status = WEAR_LEVELING_FAILED;
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}
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// Verify the FNV1a_64 result
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if (status != WEAR_LEVELING_FAILED) {
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uint64_t expected = fnv_64a_buf(wear_leveling.cache, (WEAR_LEVELING_LOGICAL_SIZE), FNV1A_64_INIT);
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write_log_entry_t entry;
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wl_dprintf("Reading checksum\n");
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#if BACKING_STORE_WRITE_SIZE == 2
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backing_store_read_bulk((WEAR_LEVELING_LOGICAL_SIZE), entry.raw16, 4);
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#elif BACKING_STORE_WRITE_SIZE == 4
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backing_store_read_bulk((WEAR_LEVELING_LOGICAL_SIZE), entry.raw32, 2);
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#elif BACKING_STORE_WRITE_SIZE == 8
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backing_store_read((WEAR_LEVELING_LOGICAL_SIZE) + 0, &entry.raw64);
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#endif
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// If we have a mismatch, clear the cache but do not flag a failure,
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// which will cater for the completely clean MCU case.
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if (entry.raw64 == expected) {
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wl_dprintf("Checksum matches, consolidated data is correct\n");
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} else {
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wl_dprintf("Checksum mismatch, clearing cache\n");
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wear_leveling_clear_cache();
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}
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}
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// If we failed for any reason, then clear the cache
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if (status == WEAR_LEVELING_FAILED) {
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wear_leveling_clear_cache();
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}
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return status;
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}
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/**
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* Writes the current cache to consolidated data at the beginning of the backing store.
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* Does not clear the write log.
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* Pre-condition: this is just after an erase, so we can write directly without reading.
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*/
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static wear_leveling_status_t wear_leveling_write_consolidated(void) {
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wl_dprintf("Writing consolidated data\n");
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backing_store_lock_status_t lock_status = wear_leveling_unlock();
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wear_leveling_status_t status = WEAR_LEVELING_CONSOLIDATED;
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if (!backing_store_write_bulk(0, (backing_store_int_t *)wear_leveling.cache, sizeof(wear_leveling.cache) / sizeof(backing_store_int_t))) {
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wl_dprintf("Failed to write to backing store\n");
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status = WEAR_LEVELING_FAILED;
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}
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if (status != WEAR_LEVELING_FAILED) {
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// Write out the FNV1a_64 result of the consolidated data
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write_log_entry_t entry;
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entry.raw64 = fnv_64a_buf(wear_leveling.cache, (WEAR_LEVELING_LOGICAL_SIZE), FNV1A_64_INIT);
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wl_dprintf("Writing checksum\n");
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do {
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#if BACKING_STORE_WRITE_SIZE == 2
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if (!backing_store_write_bulk((WEAR_LEVELING_LOGICAL_SIZE), entry.raw16, 4)) {
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status = WEAR_LEVELING_FAILED;
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break;
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}
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#elif BACKING_STORE_WRITE_SIZE == 4
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if (!backing_store_write_bulk((WEAR_LEVELING_LOGICAL_SIZE), entry.raw32, 2)) {
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status = WEAR_LEVELING_FAILED;
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break;
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}
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#elif BACKING_STORE_WRITE_SIZE == 8
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if (!backing_store_write((WEAR_LEVELING_LOGICAL_SIZE), entry.raw64)) {
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status = WEAR_LEVELING_FAILED;
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break;
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}
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#endif
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} while (0);
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}
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if (lock_status == STATUS_SUCCESS) {
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wear_leveling_lock();
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}
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return status;
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}
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/**
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* Forces a write of the current cache.
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* Erases the backing store, including the write log.
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* During this operation, there is the potential for data loss if a power loss occurs.
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*/
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static wear_leveling_status_t wear_leveling_consolidate_force(void) {
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wl_dprintf("Erasing backing store\n");
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// Erase the backing store. Expectation is that any un-written values that are read back after this call come back as zero.
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bool ok = backing_store_erase();
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if (!ok) {
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wl_dprintf("Failed to erase backing store\n");
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return WEAR_LEVELING_FAILED;
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}
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// Write the cache to the first section of the backing store.
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wear_leveling_status_t status = wear_leveling_write_consolidated();
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if (status == WEAR_LEVELING_FAILED) {
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wl_dprintf("Failed to write consolidated data\n");
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}
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// Next write of the log occurs after the consolidated values at the start of the backing store.
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wear_leveling.write_address = (WEAR_LEVELING_LOGICAL_SIZE) + 8; // +8 due to the FNV1a_64 of the consolidated area
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return status;
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}
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/**
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* Potential write of the current cache to the backing store.
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* Skipped if the current write log position is not at the end of the backing store.
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* During this operation, there is the potential for data loss if a power loss occurs.
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*
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* @return true if consolidation occurred
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*/
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static wear_leveling_status_t wear_leveling_consolidate_if_needed(void) {
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if (wear_leveling.write_address >= (WEAR_LEVELING_BACKING_SIZE)) {
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return wear_leveling_consolidate_force();
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}
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return WEAR_LEVELING_SUCCESS;
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}
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/**
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* Appends the supplied fixed-width entry to the write log, optionally consolidating if the log is full.
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*
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* @return true if consolidation occurred
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*/
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static wear_leveling_status_t wear_leveling_append_raw(backing_store_int_t value) {
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bool ok = backing_store_write(wear_leveling.write_address, value);
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if (!ok) {
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wl_dprintf("Failed to write to backing store\n");
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return WEAR_LEVELING_FAILED;
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}
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wear_leveling.write_address += (BACKING_STORE_WRITE_SIZE);
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return wear_leveling_consolidate_if_needed();
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}
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/**
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* Handles writing multi_byte-encoded data to the backing store.
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*
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* @return true if consolidation occurred
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*/
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static wear_leveling_status_t wear_leveling_write_raw_multibyte(uint32_t address, const void *value, size_t length) {
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const uint8_t * p = value;
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write_log_entry_t log = LOG_ENTRY_MAKE_MULTIBYTE(address, length);
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for (size_t i = 0; i < length; ++i) {
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log.raw8[3 + i] = p[i];
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}
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// Write to the backing store. See the multi-byte log format in the documentation header at the top of the file.
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wear_leveling_status_t status;
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#if BACKING_STORE_WRITE_SIZE == 2
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status = wear_leveling_append_raw(log.raw16[0]);
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if (status != WEAR_LEVELING_SUCCESS) {
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return status;
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}
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status = wear_leveling_append_raw(log.raw16[1]);
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if (status != WEAR_LEVELING_SUCCESS) {
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return status;
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}
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if (length > 1) {
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status = wear_leveling_append_raw(log.raw16[2]);
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if (status != WEAR_LEVELING_SUCCESS) {
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return status;
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}
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}
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if (length > 3) {
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status = wear_leveling_append_raw(log.raw16[3]);
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if (status != WEAR_LEVELING_SUCCESS) {
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return status;
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}
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}
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#elif BACKING_STORE_WRITE_SIZE == 4
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status = wear_leveling_append_raw(log.raw32[0]);
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if (status != WEAR_LEVELING_SUCCESS) {
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return status;
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}
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if (length > 1) {
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status = wear_leveling_append_raw(log.raw32[1]);
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if (status != WEAR_LEVELING_SUCCESS) {
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return status;
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}
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}
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#elif BACKING_STORE_WRITE_SIZE == 8
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status = wear_leveling_append_raw(log.raw64);
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if (status != WEAR_LEVELING_SUCCESS) {
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return status;
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}
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#endif
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return status;
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}
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/**
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* Handles the actual writing of logical data into the write log section of the backing store.
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*/
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static wear_leveling_status_t wear_leveling_write_raw(uint32_t address, const void *value, size_t length) {
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const uint8_t * p = value;
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size_t remaining = length;
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wear_leveling_status_t status = WEAR_LEVELING_SUCCESS;
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while (remaining > 0) {
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#if BACKING_STORE_WRITE_SIZE == 2
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// Small-write optimizations - uint16_t, 0 or 1, address is even, address <16384:
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if (remaining >= 2 && address % 2 == 0 && address < 16384) {
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const uint16_t v = *(const uint16_t *)p;
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if (v == 0 || v == 1) {
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const write_log_entry_t log = LOG_ENTRY_MAKE_WORD_01(address, v);
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status = wear_leveling_append_raw(log.raw16[0]);
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if (status != WEAR_LEVELING_SUCCESS) {
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// If consolidation occurred, then the cache has already been written to the consolidated area. No need to continue.
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// If a failure occurred, pass it on.
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return status;
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}
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remaining -= 2;
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address += 2;
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p += 2;
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continue;
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}
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}
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// Small-write optimizations - address<64:
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if (address < 64) {
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const write_log_entry_t log = LOG_ENTRY_MAKE_OPTIMIZED_64(address, *p);
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status = wear_leveling_append_raw(log.raw16[0]);
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if (status != WEAR_LEVELING_SUCCESS) {
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// If consolidation occurred, then the cache has already been written to the consolidated area. No need to continue.
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// If a failure occurred, pass it on.
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return status;
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}
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remaining--;
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address++;
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p++;
|
|
continue;
|
|
}
|
|
#endif // BACKING_STORE_WRITE_SIZE == 2
|
|
const size_t this_length = remaining >= LOG_ENTRY_MULTIBYTE_MAX_BYTES ? LOG_ENTRY_MULTIBYTE_MAX_BYTES : remaining;
|
|
status = wear_leveling_write_raw_multibyte(address, p, this_length);
|
|
if (status != WEAR_LEVELING_SUCCESS) {
|
|
// If consolidation occurred, then the cache has already been written to the consolidated area. No need to continue.
|
|
// If a failure occurred, pass it on.
|
|
return status;
|
|
}
|
|
remaining -= this_length;
|
|
address += (uint32_t)this_length;
|
|
p += this_length;
|
|
}
|
|
|
|
return status;
|
|
}
|
|
|
|
/**
|
|
* "Replays" the write log from the backing store, updating the local cache with updated values.
|
|
*/
|
|
static wear_leveling_status_t wear_leveling_playback_log(void) {
|
|
wl_dprintf("Playback write log\n");
|
|
|
|
wear_leveling_status_t status = WEAR_LEVELING_SUCCESS;
|
|
bool cancel_playback = false;
|
|
uint32_t address = (WEAR_LEVELING_LOGICAL_SIZE) + 8; // +8 due to the FNV1a_64 of the consolidated area
|
|
while (!cancel_playback && address < (WEAR_LEVELING_BACKING_SIZE)) {
|
|
backing_store_int_t value;
|
|
bool ok = backing_store_read(address, &value);
|
|
if (!ok) {
|
|
wl_dprintf("Failed to load from backing store, skipping playback of write log\n");
|
|
cancel_playback = true;
|
|
status = WEAR_LEVELING_FAILED;
|
|
break;
|
|
}
|
|
if (value == 0) {
|
|
wl_dprintf("Found empty slot, no more log entries\n");
|
|
cancel_playback = true;
|
|
break;
|
|
}
|
|
|
|
// If we got a nonzero value, then we need to increment the address to ensure next write occurs at next location
|
|
address += (BACKING_STORE_WRITE_SIZE);
|
|
|
|
// Read from the write log
|
|
write_log_entry_t log;
|
|
#if BACKING_STORE_WRITE_SIZE == 2
|
|
log.raw16[0] = value;
|
|
#elif BACKING_STORE_WRITE_SIZE == 4
|
|
log.raw32[0] = value;
|
|
#elif BACKING_STORE_WRITE_SIZE == 8
|
|
log.raw64 = value;
|
|
#endif
|
|
|
|
switch (LOG_ENTRY_GET_TYPE(log)) {
|
|
case LOG_ENTRY_TYPE_MULTIBYTE: {
|
|
#if BACKING_STORE_WRITE_SIZE == 2
|
|
ok = backing_store_read(address, &log.raw16[1]);
|
|
if (!ok) {
|
|
wl_dprintf("Failed to load from backing store, skipping playback of write log\n");
|
|
cancel_playback = true;
|
|
status = WEAR_LEVELING_FAILED;
|
|
break;
|
|
}
|
|
address += (BACKING_STORE_WRITE_SIZE);
|
|
#endif // BACKING_STORE_WRITE_SIZE == 2
|
|
const uint32_t a = LOG_ENTRY_MULTIBYTE_GET_ADDRESS(log);
|
|
const uint8_t l = LOG_ENTRY_MULTIBYTE_GET_LENGTH(log);
|
|
|
|
if (a + l > (WEAR_LEVELING_LOGICAL_SIZE)) {
|
|
cancel_playback = true;
|
|
status = WEAR_LEVELING_FAILED;
|
|
break;
|
|
}
|
|
|
|
#if BACKING_STORE_WRITE_SIZE == 2
|
|
if (l > 1) {
|
|
ok = backing_store_read(address, &log.raw16[2]);
|
|
if (!ok) {
|
|
wl_dprintf("Failed to load from backing store, skipping playback of write log\n");
|
|
cancel_playback = true;
|
|
status = WEAR_LEVELING_FAILED;
|
|
break;
|
|
}
|
|
address += (BACKING_STORE_WRITE_SIZE);
|
|
}
|
|
if (l > 3) {
|
|
ok = backing_store_read(address, &log.raw16[3]);
|
|
if (!ok) {
|
|
wl_dprintf("Failed to load from backing store, skipping playback of write log\n");
|
|
cancel_playback = true;
|
|
status = WEAR_LEVELING_FAILED;
|
|
break;
|
|
}
|
|
address += (BACKING_STORE_WRITE_SIZE);
|
|
}
|
|
#elif BACKING_STORE_WRITE_SIZE == 4
|
|
if (l > 1) {
|
|
ok = backing_store_read(address, &log.raw32[1]);
|
|
if (!ok) {
|
|
wl_dprintf("Failed to load from backing store, skipping playback of write log\n");
|
|
cancel_playback = true;
|
|
status = WEAR_LEVELING_FAILED;
|
|
break;
|
|
}
|
|
address += (BACKING_STORE_WRITE_SIZE);
|
|
}
|
|
#endif
|
|
|
|
memcpy(&wear_leveling.cache[a], &log.raw8[3], l);
|
|
} break;
|
|
#if BACKING_STORE_WRITE_SIZE == 2
|
|
case LOG_ENTRY_TYPE_OPTIMIZED_64: {
|
|
const uint32_t a = LOG_ENTRY_OPTIMIZED_64_GET_ADDRESS(log);
|
|
const uint8_t v = LOG_ENTRY_OPTIMIZED_64_GET_VALUE(log);
|
|
|
|
if (a >= (WEAR_LEVELING_LOGICAL_SIZE)) {
|
|
cancel_playback = true;
|
|
status = WEAR_LEVELING_FAILED;
|
|
break;
|
|
}
|
|
|
|
wear_leveling.cache[a] = v;
|
|
} break;
|
|
case LOG_ENTRY_TYPE_WORD_01: {
|
|
const uint32_t a = LOG_ENTRY_WORD_01_GET_ADDRESS(log);
|
|
const uint8_t v = LOG_ENTRY_WORD_01_GET_VALUE(log);
|
|
|
|
if (a + 1 >= (WEAR_LEVELING_LOGICAL_SIZE)) {
|
|
cancel_playback = true;
|
|
status = WEAR_LEVELING_FAILED;
|
|
break;
|
|
}
|
|
|
|
wear_leveling.cache[a + 0] = v;
|
|
wear_leveling.cache[a + 1] = 0;
|
|
} break;
|
|
#endif // BACKING_STORE_WRITE_SIZE == 2
|
|
default: {
|
|
cancel_playback = true;
|
|
status = WEAR_LEVELING_FAILED;
|
|
} break;
|
|
}
|
|
}
|
|
|
|
// We've reached the end of the log, so we're at the new write location
|
|
wear_leveling.write_address = address;
|
|
|
|
if (status == WEAR_LEVELING_FAILED) {
|
|
// If we had a failure during readback, assume we're corrupted -- force a consolidation with the data we already have
|
|
status = wear_leveling_consolidate_force();
|
|
} else {
|
|
// Consolidate the cache + write log if required
|
|
status = wear_leveling_consolidate_if_needed();
|
|
}
|
|
|
|
return status;
|
|
}
|
|
|
|
/**
|
|
* Wear-leveling initialization
|
|
*/
|
|
wear_leveling_status_t wear_leveling_init(void) {
|
|
wl_dprintf("Init\n");
|
|
|
|
// Reset the cache
|
|
wear_leveling_clear_cache();
|
|
|
|
// Initialise the backing store
|
|
if (!backing_store_init()) {
|
|
// If it failed, clear the cache and return with failure
|
|
wear_leveling_clear_cache();
|
|
return WEAR_LEVELING_FAILED;
|
|
}
|
|
|
|
// Read the previous consolidated values, then replay the existing write log so that the cache has the "live" values
|
|
wear_leveling_status_t status = wear_leveling_read_consolidated();
|
|
if (status == WEAR_LEVELING_FAILED) {
|
|
// If it failed, clear the cache and return with failure
|
|
wear_leveling_clear_cache();
|
|
return status;
|
|
}
|
|
|
|
status = wear_leveling_playback_log();
|
|
if (status == WEAR_LEVELING_FAILED) {
|
|
// If it failed, clear the cache and return with failure
|
|
wear_leveling_clear_cache();
|
|
return status;
|
|
}
|
|
|
|
return status;
|
|
}
|
|
|
|
/**
|
|
* Wear-leveling erase.
|
|
* Post-condition: any reads from the backing store directly after an erase operation must come back as zero.
|
|
*/
|
|
wear_leveling_status_t wear_leveling_erase(void) {
|
|
wl_dprintf("Erase\n");
|
|
|
|
// Unlock the backing store
|
|
backing_store_lock_status_t lock_status = wear_leveling_unlock();
|
|
if (lock_status == STATUS_FAILURE) {
|
|
wear_leveling_lock();
|
|
return WEAR_LEVELING_FAILED;
|
|
}
|
|
|
|
// Perform the erase
|
|
bool ret = backing_store_erase();
|
|
wear_leveling_clear_cache();
|
|
|
|
// Lock the backing store if we acquired the lock successfully
|
|
if (lock_status == STATUS_SUCCESS) {
|
|
ret &= (wear_leveling_lock() != STATUS_FAILURE);
|
|
}
|
|
|
|
return ret ? WEAR_LEVELING_SUCCESS : WEAR_LEVELING_FAILED;
|
|
}
|
|
|
|
/**
|
|
* Writes logical data into the backing store. Skips writes if there are no changes to values.
|
|
*/
|
|
wear_leveling_status_t wear_leveling_write(const uint32_t address, const void *value, size_t length) {
|
|
wl_assert(address + length <= (WEAR_LEVELING_LOGICAL_SIZE));
|
|
if (address + length > (WEAR_LEVELING_LOGICAL_SIZE)) {
|
|
return WEAR_LEVELING_FAILED;
|
|
}
|
|
|
|
wl_dprintf("Write ");
|
|
wl_dump(address, value, length);
|
|
|
|
// Skip write if there's no change compared to the current cached value
|
|
if (memcmp(value, &wear_leveling.cache[address], length) == 0) {
|
|
return true;
|
|
}
|
|
|
|
// Update the cache before writing to the backing store -- if we hit the end of the backing store during writes to the log then we'll force a consolidation in-line
|
|
memcpy(&wear_leveling.cache[address], value, length);
|
|
|
|
// Unlock the backing store
|
|
backing_store_lock_status_t lock_status = wear_leveling_unlock();
|
|
if (lock_status == STATUS_FAILURE) {
|
|
wear_leveling_lock();
|
|
return WEAR_LEVELING_FAILED;
|
|
}
|
|
|
|
// Perform the actual write
|
|
wear_leveling_status_t status = wear_leveling_write_raw(address, value, length);
|
|
switch (status) {
|
|
case WEAR_LEVELING_CONSOLIDATED:
|
|
case WEAR_LEVELING_FAILED:
|
|
// If the write triggered consolidation, or the write failed, then nothing else needs to occur.
|
|
break;
|
|
|
|
case WEAR_LEVELING_SUCCESS:
|
|
// Consolidate the cache + write log if required
|
|
status = wear_leveling_consolidate_if_needed();
|
|
break;
|
|
|
|
default:
|
|
// Unsure how we'd get here...
|
|
status = WEAR_LEVELING_FAILED;
|
|
break;
|
|
}
|
|
|
|
if (lock_status == STATUS_SUCCESS) {
|
|
if (wear_leveling_lock() == STATUS_FAILURE) {
|
|
status = WEAR_LEVELING_FAILED;
|
|
}
|
|
}
|
|
|
|
return status;
|
|
}
|
|
|
|
/**
|
|
* Reads logical data from the cache.
|
|
*/
|
|
wear_leveling_status_t wear_leveling_read(const uint32_t address, void *value, size_t length) {
|
|
wl_assert(address + length <= (WEAR_LEVELING_LOGICAL_SIZE));
|
|
if (address + length > (WEAR_LEVELING_LOGICAL_SIZE)) {
|
|
return WEAR_LEVELING_FAILED;
|
|
}
|
|
|
|
// Only need to copy from the cache
|
|
memcpy(value, &wear_leveling.cache[address], length);
|
|
|
|
wl_dprintf("Read ");
|
|
wl_dump(address, value, length);
|
|
return WEAR_LEVELING_SUCCESS;
|
|
}
|
|
|
|
/**
|
|
* Weak implementation of bulk read, drivers can implement more optimised implementations.
|
|
*/
|
|
__attribute__((weak)) bool backing_store_read_bulk(uint32_t address, backing_store_int_t *values, size_t item_count) {
|
|
for (size_t i = 0; i < item_count; ++i) {
|
|
if (!backing_store_read(address + (i * BACKING_STORE_WRITE_SIZE), &values[i])) {
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* Weak implementation of bulk write, drivers can implement more optimised implementations.
|
|
*/
|
|
__attribute__((weak)) bool backing_store_write_bulk(uint32_t address, backing_store_int_t *values, size_t item_count) {
|
|
for (size_t i = 0; i < item_count; ++i) {
|
|
if (!backing_store_write(address + (i * BACKING_STORE_WRITE_SIZE), values[i])) {
|
|
return false;
|
|
}
|
|
}
|
|
return true;
|
|
} |