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>

1 files changed, 54 insertions, 0 deletions

diff --git a/quantum/wear_leveling/wear_leveling.h b/quantum/wear_leveling/wear_leveling.h
new file mode 100644
index 0000000000..6641bc49b3
--- /dev/null
+++ b/quantum/wear_leveling/wear_leveling.h
@@ -0,0 +1,54 @@
+// Copyright 2022 Nick Brassel (@tzarc)
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+#include <stdint.h>
+#include <stdlib.h>
+
+/**
+ * @typedef Status returned from any wear-leveling API.
+ */
+typedef enum wear_leveling_status_t {
+    WEAR_LEVELING_FAILED,      //< Invocation failed
+    WEAR_LEVELING_SUCCESS,     //< Invocation succeeded
+    WEAR_LEVELING_CONSOLIDATED //< Invocation succeeded, consolidation occurred
+} wear_leveling_status_t;
+
+/**
+ * Wear-leveling initialization
+ *
+ * @return Status of the request
+ */
+wear_leveling_status_t wear_leveling_init(void);
+
+/**
+ * Wear-leveling erasure.
+ *
+ * Clears the wear-leveling area, with the definition that the "reset state" of all data is zero.
+ *
+ * @return Status of the request
+ */
+wear_leveling_status_t wear_leveling_erase(void);
+
+/**
+ * Writes logical data into the backing store.
+ *
+ * Skips writes if there are no changes to written values. The entire written block is considered when attempting to
+ * determine if an overwrite should occur -- if there is any data mismatch the entire block will be written to the log,
+ * not just the changed bytes.
+ *
+ * @param address[in] the logical address to write data
+ * @param value[in] pointer to the source buffer
+ * @param length[in] length of the data
+ * @return Status of the request
+ */
+wear_leveling_status_t wear_leveling_write(uint32_t address, const void* value, size_t length);
+
+/**
+ * Reads logical data from the cache.
+ *
+ * @param address[in] the logical address to read data
+ * @param value[out] pointer to the destination buffer
+ * @param length[in] length of the data
+ * @return Status of the request
+ */
+wear_leveling_status_t wear_leveling_read(uint32_t address, void* value, size_t length);