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