Generic wear-leveling algorithm (#16996)

* Initial import of wear-leveling algorithm.

* Alignment.

* Docs tweaks.

* Lock/unlock.

* Update quantum/wear_leveling/wear_leveling_internal.h

Co-authored-by: Stefan Kerkmann <karlk90@pm.me>

* More tests, fix issue with consolidation when unlocked.

* More tests.

* Review comments.

* Add plumbing for FNV1a.

* Another test checking that checksum mismatch clears the cache.

* Check that the write log still gets played back.

Co-authored-by: Stefan Kerkmann <karlk90@pm.me>

quantum/wear_leveling/tests/backing_mocks.hpp

@@ -0,0 +1,210 @@
+// Copyright 2022 Nick Brassel (@tzarc)
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+#include <algorithm>
+#include <array>
+#include <cstdint>
+#include <cstdlib>
+#include <functional>
+#include <type_traits>
+#include <vector>
+
+extern "C" {
+#include "fnv.h"
+#include "wear_leveling.h"
+#include "wear_leveling_internal.h"
+};
+
+// Maximum number of mock write log entries to keep
+using MOCK_WRITE_LOG_MAX_ENTRIES = std::integral_constant<std::size_t, 1024>;
+// Complement to the backing store integral, for emulating flash erases of all bytes=0xFF
+using BACKING_STORE_INTEGRAL_COMPLEMENT = std::integral_constant<backing_store_int_t, ((backing_store_int_t)(~(backing_store_int_t)0))>;
+// Total number of elements stored in the backing arrays
+using BACKING_STORE_ELEMENT_COUNT = std::integral_constant<std::size_t, (WEAR_LEVELING_BACKING_SIZE / sizeof(backing_store_int_t))>;
+
+class MockBackingStoreElement {
+   private:
+    backing_store_int_t value;
+    std::size_t         writes;
+    std::size_t         erases;
+
+   public:
+    MockBackingStoreElement() : value(BACKING_STORE_INTEGRAL_COMPLEMENT::value), writes(0), erases(0) {}
+    void reset() {
+        erase();
+        writes = 0;
+        erases = 0;
+    }
+    void erase() {
+        if (!is_erased()) {
+            ++erases;
+        }
+        value = BACKING_STORE_INTEGRAL_COMPLEMENT::value;
+    }
+    backing_store_int_t get() const {
+        return value;
+    }
+    void set(const backing_store_int_t& v) {
+        EXPECT_TRUE(is_erased()) << "Attempted write at index which isn't empty.";
+        value = v;
+        ++writes;
+    }
+    std::size_t num_writes() const {
+        return writes;
+    }
+    std::size_t num_erases() const {
+        return erases;
+    }
+    bool is_erased() const {
+        return value == BACKING_STORE_INTEGRAL_COMPLEMENT::value;
+    }
+};
+
+struct MockBackingStoreLogEntry {
+    MockBackingStoreLogEntry(uint32_t address, backing_store_int_t value) : address(address), value(value), erased(false) {}
+    MockBackingStoreLogEntry(bool erased) : address(0), value(0), erased(erased) {}
+    uint32_t            address = 0;     // The address of the operation
+    backing_store_int_t value   = 0;     // The value of the operation
+    bool                erased  = false; // Whether the entire backing store was erased
+};
+
+class MockBackingStore {
+   private:
+    MockBackingStore() {
+        reset_instance();
+    }
+
+    // Type containing each of the entries and the write counts
+    using storage_t = std::array<MockBackingStoreElement, BACKING_STORE_ELEMENT_COUNT::value>;
+
+    // Whether the backing store is locked
+    bool locked;
+    // The actual data stored in the emulated flash
+    storage_t backing_storage;
+    // The number of erase cycles that have occurred
+    std::uint64_t backing_erasure_count;
+    // The max number of writes to an element of the backing store
+    std::uint64_t backing_max_write_count;
+    // The total number of writes to all elements of the backing store
+    std::uint64_t backing_total_write_count;
+    // The write log for the backing store
+    std::vector<MockBackingStoreLogEntry> write_log;
+
+    // The number of times each API was invoked
+    std::uint64_t backing_init_invoke_count;
+    std::uint64_t backing_unlock_invoke_count;
+    std::uint64_t backing_erase_invoke_count;
+    std::uint64_t backing_write_invoke_count;
+    std::uint64_t backing_lock_invoke_count;
+
+    // Whether init should succeed
+    std::function<bool(std::uint64_t)> init_success_callback;
+    // Whether erase should succeed
+    std::function<bool(std::uint64_t)> erase_success_callback;
+    // Whether unlocks should succeed
+    std::function<bool(std::uint64_t)> unlock_success_callback;
+    // Whether writes should succeed
+    std::function<bool(std::uint64_t, std::uint32_t)> write_success_callback;
+    // Whether locks should succeed
+    std::function<bool(std::uint64_t)> lock_success_callback;
+
+    template <typename... Args>
+    void append_log(Args&&... args) {
+        if (write_log.size() < MOCK_WRITE_LOG_MAX_ENTRIES::value) {
+            write_log.emplace_back(std::forward<Args>(args)...);
+        }
+    }
+
+   public:
+    static MockBackingStore& Instance() {
+        static MockBackingStore instance;
+        return instance;
+    }
+
+    std::uint64_t erasure_count() const {
+        return backing_erasure_count;
+    }
+    std::uint64_t max_write_count() const {
+        return backing_max_write_count;
+    }
+    std::uint64_t total_write_count() const {
+        return backing_total_write_count;
+    }
+
+    // The number of times each API was invoked
+    std::uint64_t init_invoke_count() const {
+        return backing_init_invoke_count;
+    }
+    std::uint64_t unlock_invoke_count() const {
+        return backing_unlock_invoke_count;
+    }
+    std::uint64_t erase_invoke_count() const {
+        return backing_erase_invoke_count;
+    }
+    std::uint64_t write_invoke_count() const {
+        return backing_write_invoke_count;
+    }
+    std::uint64_t lock_invoke_count() const {
+        return backing_lock_invoke_count;
+    }
+
+    // Clear out the internal data for the next run
+    void reset_instance();
+
+    bool is_locked() const {
+        return locked;
+    }
+
+    // APIs for the backing store
+    bool init();
+    bool unlock();
+    bool erase();
+    bool write(std::uint32_t address, backing_store_int_t value);
+    bool lock();
+    bool read(std::uint32_t address, backing_store_int_t& value) const;
+
+    // Control over when init/writes/erases should succeed
+    void set_init_callback(std::function<bool(std::uint64_t)> callback) {
+        init_success_callback = callback;
+    }
+    void set_erase_callback(std::function<bool(std::uint64_t)> callback) {
+        erase_success_callback = callback;
+    }
+    void set_unlock_callback(std::function<bool(std::uint64_t)> callback) {
+        unlock_success_callback = callback;
+    }
+    void set_write_callback(std::function<bool(std::uint64_t, std::uint32_t)> callback) {
+        write_success_callback = callback;
+    }
+    void set_lock_callback(std::function<bool(std::uint64_t)> callback) {
+        lock_success_callback = callback;
+    }
+
+    auto storage_begin() const -> decltype(backing_storage.begin()) {
+        return backing_storage.begin();
+    }
+    auto storage_end() const -> decltype(backing_storage.end()) {
+        return backing_storage.end();
+    }
+
+    auto storage_begin() -> decltype(backing_storage.begin()) {
+        return backing_storage.begin();
+    }
+    auto storage_end() -> decltype(backing_storage.end()) {
+        return backing_storage.end();
+    }
+
+    auto log_begin() -> decltype(write_log.begin()) {
+        return write_log.begin();
+    }
+    auto log_end() -> decltype(write_log.end()) {
+        return write_log.end();
+    }
+
+    auto log_begin() const -> decltype(write_log.begin()) {
+        return write_log.begin();
+    }
+    auto log_end() const -> decltype(write_log.end()) {
+        return write_log.end();
+    }
+};