Rework paths for eeprom locations. (#17326)

* Rework paths for eeprom locations.

* File relocation.

* Wrong file move.

* Fixup test paths.

5 files changed, 1369 insertions, 0 deletions

diff --git a/platforms/chibios/drivers/eeprom/eeprom_stm32.c b/platforms/chibios/drivers/eeprom/eeprom_stm32.c
new file mode 100644
index 0000000000..a15bfe09ed
--- /dev/null
+++ b/platforms/chibios/drivers/eeprom/eeprom_stm32.c
@@ -0,0 +1,629 @@
+/*
+ * This software is experimental and a work in progress.
+ * Under no circumstances should these files be used in relation to any critical system(s).
+ * Use of these files is at your own risk.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+ * PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * This files are free to use from http://engsta.com/stm32-flash-memory-eeprom-emulator/ by
+ * Artur F.
+ *
+ * Modifications for QMK and STM32F303 by Yiancar
+ * Modifications to add flash wear leveling by Ilya Zhuravlev
+ * Modifications to increase flash density by Don Kjer
+ */
+
+#include <stdio.h>
+#include <stdbool.h>
+#include "util.h"
+#include "debug.h"
+#include "eeprom_stm32.h"
+#include "flash_stm32.h"
+
+/*
+ * We emulate eeprom by writing a snapshot compacted view of eeprom contents,
+ * followed by a write log of any change since that snapshot:
+ *
+ * === SIMULATED EEPROM CONTENTS ===
+ *
+ * ┌─ Compacted ┬ Write Log ─┐
+ * │............│[BYTE][BYTE]│
+ * │FFFF....FFFF│[WRD0][WRD1]│
+ * │FFFFFFFFFFFF│[WORD][NEXT]│
+ * │....FFFFFFFF│[BYTE][WRD0]│
+ * ├────────────┼────────────┤
+ * └──PAGE_BASE │            │
+ *    PAGE_LAST─┴─WRITE_BASE │
+ *                WRITE_LAST ┘
+ *
+ * Compacted contents are the 1's complement of the actual EEPROM contents.
+ * e.g. An 'FFFF' represents a '0000' value.
+ *
+ * The size of the 'compacted' area is equal to the size of the 'emulated' eeprom.
+ * The size of the compacted-area and write log are configurable, and the combined
+ * size of Compacted + WriteLog is a multiple FEE_PAGE_SIZE, which is MCU dependent.
+ * Simulated Eeprom contents are located at the end of available flash space.
+ *
+ * The following configuration defines can be set:
+ *
+ * FEE_PAGE_COUNT   # Total number of pages to use for eeprom simulation (Compact + Write log)
+ * FEE_DENSITY_BYTES   # Size of simulated eeprom. (Defaults to half the space allocated by FEE_PAGE_COUNT)
+ * NOTE: The current implementation does not include page swapping,
+ * and FEE_DENSITY_BYTES will consume that amount of RAM as a cached view of actual EEPROM contents.
+ *
+ * The maximum size of FEE_DENSITY_BYTES is currently 16384. The write log size equals
+ * FEE_PAGE_COUNT * FEE_PAGE_SIZE - FEE_DENSITY_BYTES.
+ * The larger the write log, the less frequently the compacted area needs to be rewritten.
+ *
+ *
+ * *** General Algorithm ***
+ *
+ * During initialization:
+ * The contents of the Compacted-flash area are loaded and the 1's complement value
+ * is cached into memory (e.g. 0xFFFF in Flash represents 0x0000 in cache).
+ * Write log entries are processed until a 0xFFFF is reached.
+ * Each log entry updates a byte or word in the cache.
+ *
+ * During reads:
+ * EEPROM contents are given back directly from the cache in memory.
+ *
+ * During writes:
+ * The contents of the cache is updated first.
+ * If the Compacted-flash area corresponding to the write address is unprogrammed, the 1's complement of the value is written directly into Compacted-flash
+ * Otherwise:
+ * If the write log is full, erase both the Compacted-flash area and the Write log, then write cached contents to the Compacted-flash area.
+ * Otherwise a Write log entry is constructed and appended to the next free position in the Write log.
+ *
+ *
+ * *** Write Log Structure ***
+ *
+ * Write log entries allow for optimized byte writes to addresses below 128. Writing 0 or 1 words are also optimized when word-aligned.
+ *
+ * === WRITE LOG ENTRY FORMATS ===
+ *
+ * ╔═══ Byte-Entry ══╗
+ * ║0XXXXXXX║YYYYYYYY║
+ * ║ └──┬──┘║└──┬───┘║
+ * ║ Address║ Value  ║
+ * ╚════════╩════════╝
+ * 0 <= Address < 0x80 (128)
+ *
+ * ╔ Word-Encoded 0 ╗
+ * ║100XXXXXXXXXXXXX║
+ * ║  │└─────┬─────┘║
+ * ║  │Address >> 1 ║
+ * ║  └── Value: 0  ║
+ * ╚════════════════╝
+ * 0 <= Address <= 0x3FFE (16382)
+ *
+ * ╔ Word-Encoded 1 ╗
+ * ║101XXXXXXXXXXXXX║
+ * ║  │└─────┬─────┘║
+ * ║  │Address >> 1 ║
+ * ║  └── Value: 1  ║
+ * ╚════════════════╝
+ * 0 <= Address <= 0x3FFE (16382)
+ *
+ * ╔═══ Reserved ═══╗
+ * ║110XXXXXXXXXXXXX║
+ * ╚════════════════╝
+ *
+ * ╔═══════════ Word-Next ═══════════╗
+ * ║111XXXXXXXXXXXXX║YYYYYYYYYYYYYYYY║
+ * ║   └─────┬─────┘║└───────┬──────┘║
+ * ║(Address-128)>>1║     ~Value     ║
+ * ╚════════════════╩════════════════╝
+ * (  0 <= Address <  0x0080 (128): Reserved)
+ * 0x80 <= Address <= 0x3FFE (16382)
+ *
+ * Write Log entry ranges:
+ * 0x0000 ... 0x7FFF - Byte-Entry;     address is (Entry & 0x7F00) >> 4; value is (Entry & 0xFF)
+ * 0x8000 ... 0x9FFF - Word-Encoded 0; address is (Entry & 0x1FFF) << 1; value is 0
+ * 0xA000 ... 0xBFFF - Word-Encoded 1; address is (Entry & 0x1FFF) << 1; value is 1
+ * 0xC000 ... 0xDFFF - Reserved
+ * 0xE000 ... 0xFFBF - Word-Next;      address is (Entry & 0x1FFF) << 1 + 0x80; value is ~(Next_Entry)
+ * 0xFFC0 ... 0xFFFE - Reserved
+ * 0xFFFF            - Unprogrammed
+ *
+ */
+
+#include "eeprom_stm32_defs.h"
+/* These bits are used for optimizing encoding of bytes, 0 and 1 */
+#define FEE_WORD_ENCODING 0x8000
+#define FEE_VALUE_NEXT 0x6000
+#define FEE_VALUE_RESERVED 0x4000
+#define FEE_VALUE_ENCODED 0x2000
+#define FEE_BYTE_RANGE 0x80
+
+/* Flash word value after erase */
+#define FEE_EMPTY_WORD ((uint16_t)0xFFFF)
+
+#if !defined(FEE_PAGE_SIZE) || !defined(FEE_PAGE_COUNT) || !defined(FEE_MCU_FLASH_SIZE) || !defined(FEE_PAGE_BASE_ADDRESS)
+#    error "not implemented."
+#endif
+
+/* In-memory contents of emulated eeprom for faster access */
+/* *TODO: Implement page swapping */
+static uint16_t WordBuf[FEE_DENSITY_BYTES / 2];
+static uint8_t *DataBuf = (uint8_t *)WordBuf;
+
+/* Pointer to the first available slot within the write log */
+static uint16_t *empty_slot;
+
+// #define DEBUG_EEPROM_OUTPUT
+
+/*
+ * Debug print utils
+ */
+
+#if defined(DEBUG_EEPROM_OUTPUT)
+
+#    define debug_eeprom debug_enable
+#    define eeprom_println(s) println(s)
+#    define eeprom_printf(fmt, ...) xprintf(fmt, ##__VA_ARGS__);
+
+#else /* NO_DEBUG */
+
+#    define debug_eeprom false
+#    define eeprom_println(s)
+#    define eeprom_printf(fmt, ...)
+
+#endif /* NO_DEBUG */
+
+void print_eeprom(void) {
+#ifndef NO_DEBUG
+    int empty_rows = 0;
+    for (uint16_t i = 0; i < FEE_DENSITY_BYTES; i++) {
+        if (i % 16 == 0) {
+            if (i >= FEE_DENSITY_BYTES - 16) {
+                /* Make sure we display the last row */
+                empty_rows = 0;
+            }
+            /* Check if this row is uninitialized */
+            ++empty_rows;
+            for (uint16_t j = 0; j < 16; j++) {
+                if (DataBuf[i + j]) {
+                    empty_rows = 0;
+                    break;
+                }
+            }
+            if (empty_rows > 1) {
+                /* Repeat empty row */
+                if (empty_rows == 2) {
+                    /* Only display the first repeat empty row */
+                    println("*");
+                }
+                i += 15;
+                continue;
+            }
+            xprintf("%04x", i);
+        }
+        if (i % 8 == 0) print(" ");
+
+        xprintf(" %02x", DataBuf[i]);
+        if ((i + 1) % 16 == 0) {
+            println("");
+        }
+    }
+#endif
+}
+
+uint16_t EEPROM_Init(void) {
+    /* Load emulated eeprom contents from compacted flash into memory */
+    uint16_t *src  = (uint16_t *)FEE_COMPACTED_BASE_ADDRESS;
+    uint16_t *dest = (uint16_t *)DataBuf;
+    for (; src < (uint16_t *)FEE_COMPACTED_LAST_ADDRESS; ++src, ++dest) {
+        *dest = ~*src;
+    }
+
+    if (debug_eeprom) {
+        println("EEPROM_Init Compacted Pages:");
+        print_eeprom();
+        println("EEPROM_Init Write Log:");
+    }
+
+    /* Replay write log */
+    uint16_t *log_addr;
+    for (log_addr = (uint16_t *)FEE_WRITE_LOG_BASE_ADDRESS; log_addr < (uint16_t *)FEE_WRITE_LOG_LAST_ADDRESS; ++log_addr) {
+        uint16_t address = *log_addr;
+        if (address == FEE_EMPTY_WORD) {
+            break;
+        }
+        /* Check for lowest 128-bytes optimization */
+        if (!(address & FEE_WORD_ENCODING)) {
+            uint8_t bvalue = (uint8_t)address;
+            address >>= 8;
+            DataBuf[address] = bvalue;
+            eeprom_printf("DataBuf[0x%02x] = 0x%02x;\n", address, bvalue);
+        } else {
+            uint16_t wvalue;
+            /* Check if value is in next word */
+            if ((address & FEE_VALUE_NEXT) == FEE_VALUE_NEXT) {
+                /* Read value from next word */
+                if (++log_addr >= (uint16_t *)FEE_WRITE_LOG_LAST_ADDRESS) {
+                    break;
+                }
+                wvalue = ~*log_addr;
+                if (!wvalue) {
+                    eeprom_printf("Incomplete write at log_addr: 0x%04x;\n", (uint32_t)log_addr);
+                    /* Possibly incomplete write.  Ignore and continue */
+                    continue;
+                }
+                address &= 0x1FFF;
+                address <<= 1;
+                /* Writes to addresses less than 128 are byte log entries */
+                address += FEE_BYTE_RANGE;
+            } else {
+                /* Reserved for future use */
+                if (address & FEE_VALUE_RESERVED) {
+                    eeprom_printf("Reserved encoded value at log_addr: 0x%04x;\n", (uint32_t)log_addr);
+                    continue;
+                }
+                /* Optimization for 0 or 1 values. */
+                wvalue = (address & FEE_VALUE_ENCODED) >> 13;
+                address &= 0x1FFF;
+                address <<= 1;
+            }
+            if (address < FEE_DENSITY_BYTES) {
+                eeprom_printf("DataBuf[0x%04x] = 0x%04x;\n", address, wvalue);
+                *(uint16_t *)(&DataBuf[address]) = wvalue;
+            } else {
+                eeprom_printf("DataBuf[0x%04x] cannot be set to 0x%04x [BAD ADDRESS]\n", address, wvalue);
+            }
+        }
+    }
+
+    empty_slot = log_addr;
+
+    if (debug_eeprom) {
+        println("EEPROM_Init Final DataBuf:");
+        print_eeprom();
+    }
+
+    return FEE_DENSITY_BYTES;
+}
+
+/* Clear flash contents (doesn't touch in-memory DataBuf) */
+static void eeprom_clear(void) {
+    FLASH_Unlock();
+
+    for (uint16_t page_num = 0; page_num < FEE_PAGE_COUNT; ++page_num) {
+        eeprom_printf("FLASH_ErasePage(0x%04x)\n", (uint32_t)(FEE_PAGE_BASE_ADDRESS + (page_num * FEE_PAGE_SIZE)));
+        FLASH_ErasePage(FEE_PAGE_BASE_ADDRESS + (page_num * FEE_PAGE_SIZE));
+    }
+
+    FLASH_Lock();
+
+    empty_slot = (uint16_t *)FEE_WRITE_LOG_BASE_ADDRESS;
+    eeprom_printf("eeprom_clear empty_slot: 0x%08x\n", (uint32_t)empty_slot);
+}
+
+/* Erase emulated eeprom */
+void EEPROM_Erase(void) {
+    eeprom_println("EEPROM_Erase");
+    /* Erase compacted pages and write log */
+    eeprom_clear();
+    /* re-initialize to reset DataBuf */
+    EEPROM_Init();
+}
+
+/* Compact write log */
+static uint8_t eeprom_compact(void) {
+    /* Erase compacted pages and write log */
+    eeprom_clear();
+
+    FLASH_Unlock();
+
+    FLASH_Status final_status = FLASH_COMPLETE;
+
+    /* Write emulated eeprom contents from memory to compacted flash */
+    uint16_t *src  = (uint16_t *)DataBuf;
+    uintptr_t dest = FEE_COMPACTED_BASE_ADDRESS;
+    uint16_t  value;
+    for (; dest < FEE_COMPACTED_LAST_ADDRESS; ++src, dest += 2) {
+        value = *src;
+        if (value) {
+            eeprom_printf("FLASH_ProgramHalfWord(0x%04x, 0x%04x)\n", (uint32_t)dest, ~value);
+            FLASH_Status status = FLASH_ProgramHalfWord(dest, ~value);
+            if (status != FLASH_COMPLETE) final_status = status;
+        }
+    }
+
+    FLASH_Lock();
+
+    if (debug_eeprom) {
+        println("eeprom_compacted:");
+        print_eeprom();
+    }
+
+    return final_status;
+}
+
+static uint8_t eeprom_write_direct_entry(uint16_t Address) {
+    /* Check if we can just write this directly to the compacted flash area */
+    uintptr_t directAddress = FEE_COMPACTED_BASE_ADDRESS + (Address & 0xFFFE);
+    if (*(uint16_t *)directAddress == FEE_EMPTY_WORD) {
+        /* Write the value directly to the compacted area without a log entry */
+        uint16_t value = ~*(uint16_t *)(&DataBuf[Address & 0xFFFE]);
+        /* Early exit if a write isn't needed */
+        if (value == FEE_EMPTY_WORD) return FLASH_COMPLETE;
+
+        FLASH_Unlock();
+
+        eeprom_printf("FLASH_ProgramHalfWord(0x%08x, 0x%04x) [DIRECT]\n", (uint32_t)directAddress, value);
+        FLASH_Status status = FLASH_ProgramHalfWord(directAddress, value);
+
+        FLASH_Lock();
+        return status;
+    }
+    return 0;
+}
+
+static uint8_t eeprom_write_log_word_entry(uint16_t Address) {
+    FLASH_Status final_status = FLASH_COMPLETE;
+
+    uint16_t value = *(uint16_t *)(&DataBuf[Address]);
+    eeprom_printf("eeprom_write_log_word_entry(0x%04x): 0x%04x\n", Address, value);
+
+    /* MSB signifies the lowest 128-byte optimization is not in effect */
+    uint16_t encoding = FEE_WORD_ENCODING;
+    uint8_t  entry_size;
+    if (value <= 1) {
+        encoding |= value << 13;
+        entry_size = 2;
+    } else {
+        encoding |= FEE_VALUE_NEXT;
+        entry_size = 4;
+        /* Writes to addresses less than 128 are byte log entries */
+        Address -= FEE_BYTE_RANGE;
+    }
+
+    /* if we can't find an empty spot, we must compact emulated eeprom */
+    if (empty_slot > (uint16_t *)(FEE_WRITE_LOG_LAST_ADDRESS - entry_size)) {
+        /* compact the write log into the compacted flash area */
+        return eeprom_compact();
+    }
+
+    /* Word log writes should be word-aligned.  Take back a bit */
+    Address >>= 1;
+    Address |= encoding;
+
+    /* ok we found a place let's write our data */
+    FLASH_Unlock();
+
+    /* address */
+    eeprom_printf("FLASH_ProgramHalfWord(0x%08x, 0x%04x)\n", (uint32_t)empty_slot, Address);
+    final_status = FLASH_ProgramHalfWord((uintptr_t)empty_slot++, Address);
+
+    /* value */
+    if (encoding == (FEE_WORD_ENCODING | FEE_VALUE_NEXT)) {
+        eeprom_printf("FLASH_ProgramHalfWord(0x%08x, 0x%04x)\n", (uint32_t)empty_slot, ~value);
+        FLASH_Status status = FLASH_ProgramHalfWord((uintptr_t)empty_slot++, ~value);
+        if (status != FLASH_COMPLETE) final_status = status;
+    }
+
+    FLASH_Lock();
+
+    return final_status;
+}
+
+static uint8_t eeprom_write_log_byte_entry(uint16_t Address) {
+    eeprom_printf("eeprom_write_log_byte_entry(0x%04x): 0x%02x\n", Address, DataBuf[Address]);
+
+    /* if couldn't find an empty spot, we must compact emulated eeprom */
+    if (empty_slot >= (uint16_t *)FEE_WRITE_LOG_LAST_ADDRESS) {
+        /* compact the write log into the compacted flash area */
+        return eeprom_compact();
+    }
+
+    /* ok we found a place let's write our data */
+    FLASH_Unlock();
+
+    /* Pack address and value into the same word */
+    uint16_t value = (Address << 8) | DataBuf[Address];
+
+    /* write to flash */
+    eeprom_printf("FLASH_ProgramHalfWord(0x%08x, 0x%04x)\n", (uint32_t)empty_slot, value);
+    FLASH_Status status = FLASH_ProgramHalfWord((uintptr_t)empty_slot++, value);
+
+    FLASH_Lock();
+
+    return status;
+}
+
+uint8_t EEPROM_WriteDataByte(uint16_t Address, uint8_t DataByte) {
+    /* if the address is out-of-bounds, do nothing */
+    if (Address >= FEE_DENSITY_BYTES) {
+        eeprom_printf("EEPROM_WriteDataByte(0x%04x, 0x%02x) [BAD ADDRESS]\n", Address, DataByte);
+        return FLASH_BAD_ADDRESS;
+    }
+
+    /* if the value is the same, don't bother writing it */
+    if (DataBuf[Address] == DataByte) {
+        eeprom_printf("EEPROM_WriteDataByte(0x%04x, 0x%02x) [SKIP SAME]\n", Address, DataByte);
+        return 0;
+    }
+
+    /* keep DataBuf cache in sync */
+    DataBuf[Address] = DataByte;
+    eeprom_printf("EEPROM_WriteDataByte DataBuf[0x%04x] = 0x%02x\n", Address, DataBuf[Address]);
+
+    /* perform the write into flash memory */
+    /* First, attempt to write directly into the compacted flash area */
+    FLASH_Status status = eeprom_write_direct_entry(Address);
+    if (!status) {
+        /* Otherwise append to the write log */
+        if (Address < FEE_BYTE_RANGE) {
+            status = eeprom_write_log_byte_entry(Address);
+        } else {
+            status = eeprom_write_log_word_entry(Address & 0xFFFE);
+        }
+    }
+    if (status != 0 && status != FLASH_COMPLETE) {
+        eeprom_printf("EEPROM_WriteDataByte [STATUS == %d]\n", status);
+    }
+    return status;
+}
+
+uint8_t EEPROM_WriteDataWord(uint16_t Address, uint16_t DataWord) {
+    /* if the address is out-of-bounds, do nothing */
+    if (Address >= FEE_DENSITY_BYTES) {
+        eeprom_printf("EEPROM_WriteDataWord(0x%04x, 0x%04x) [BAD ADDRESS]\n", Address, DataWord);
+        return FLASH_BAD_ADDRESS;
+    }
+
+    /* Check for word alignment */
+    FLASH_Status final_status = FLASH_COMPLETE;
+    if (Address % 2) {
+        final_status        = EEPROM_WriteDataByte(Address, DataWord);
+        FLASH_Status status = EEPROM_WriteDataByte(Address + 1, DataWord >> 8);
+        if (status != FLASH_COMPLETE) final_status = status;
+        if (final_status != 0 && final_status != FLASH_COMPLETE) {
+            eeprom_printf("EEPROM_WriteDataWord [STATUS == %d]\n", final_status);
+        }
+        return final_status;
+    }
+
+    /* if the value is the same, don't bother writing it */
+    uint16_t oldValue = *(uint16_t *)(&DataBuf[Address]);
+    if (oldValue == DataWord) {
+        eeprom_printf("EEPROM_WriteDataWord(0x%04x, 0x%04x) [SKIP SAME]\n", Address, DataWord);
+        return 0;
+    }
+
+    /* keep DataBuf cache in sync */
+    *(uint16_t *)(&DataBuf[Address]) = DataWord;
+    eeprom_printf("EEPROM_WriteDataWord DataBuf[0x%04x] = 0x%04x\n", Address, *(uint16_t *)(&DataBuf[Address]));
+
+    /* perform the write into flash memory */
+    /* First, attempt to write directly into the compacted flash area */
+    final_status = eeprom_write_direct_entry(Address);
+    if (!final_status) {
+        /* Otherwise append to the write log */
+        /* Check if we need to fall back to byte write */
+        if (Address < FEE_BYTE_RANGE) {
+            final_status = FLASH_COMPLETE;
+            /* Only write a byte if it has changed */
+            if ((uint8_t)oldValue != (uint8_t)DataWord) {
+                final_status = eeprom_write_log_byte_entry(Address);
+            }
+            FLASH_Status status = FLASH_COMPLETE;
+            /* Only write a byte if it has changed */
+            if ((oldValue >> 8) != (DataWord >> 8)) {
+                status = eeprom_write_log_byte_entry(Address + 1);
+            }
+            if (status != FLASH_COMPLETE) final_status = status;
+        } else {
+            final_status = eeprom_write_log_word_entry(Address);
+        }
+    }
+    if (final_status != 0 && final_status != FLASH_COMPLETE) {
+        eeprom_printf("EEPROM_WriteDataWord [STATUS == %d]\n", final_status);
+    }
+    return final_status;
+}
+
+uint8_t EEPROM_ReadDataByte(uint16_t Address) {
+    uint8_t DataByte = 0xFF;
+
+    if (Address < FEE_DENSITY_BYTES) {
+        DataByte = DataBuf[Address];
+    }
+
+    eeprom_printf("EEPROM_ReadDataByte(0x%04x): 0x%02x\n", Address, DataByte);
+
+    return DataByte;
+}
+
+uint16_t EEPROM_ReadDataWord(uint16_t Address) {
+    uint16_t DataWord = 0xFFFF;
+
+    if (Address < FEE_DENSITY_BYTES - 1) {
+        /* Check word alignment */
+        if (Address % 2) {
+            DataWord = DataBuf[Address] | (DataBuf[Address + 1] << 8);
+        } else {
+            DataWord = *(uint16_t *)(&DataBuf[Address]);
+        }
+    }
+
+    eeprom_printf("EEPROM_ReadDataWord(0x%04x): 0x%04x\n", Address, DataWord);
+
+    return DataWord;
+}
+
+/*****************************************************************************
+ *  Bind to eeprom_driver.c
+ *******************************************************************************/
+void eeprom_driver_init(void) {
+    EEPROM_Init();
+}
+
+void eeprom_driver_erase(void) {
+    EEPROM_Erase();
+}
+
+void eeprom_read_block(void *buf, const void *addr, size_t len) {
+    const uint8_t *src  = (const uint8_t *)addr;
+    uint8_t *      dest = (uint8_t *)buf;
+
+    /* Check word alignment */
+    if (len && (uintptr_t)src % 2) {
+        /* Read the unaligned first byte */
+        *dest++ = EEPROM_ReadDataByte((const uintptr_t)src++);
+        --len;
+    }
+
+    uint16_t value;
+    bool     aligned = ((uintptr_t)dest % 2 == 0);
+    while (len > 1) {
+        value = EEPROM_ReadDataWord((const uintptr_t)((uint16_t *)src));
+        if (aligned) {
+            *(uint16_t *)dest = value;
+            dest += 2;
+        } else {
+            *dest++ = value;
+            *dest++ = value >> 8;
+        }
+        src += 2;
+        len -= 2;
+    }
+    if (len) {
+        *dest = EEPROM_ReadDataByte((const uintptr_t)src);
+    }
+}
+
+void eeprom_write_block(const void *buf, void *addr, size_t len) {
+    uint8_t *      dest = (uint8_t *)addr;
+    const uint8_t *src  = (const uint8_t *)buf;
+
+    /* Check word alignment */
+    if (len && (uintptr_t)dest % 2) {
+        /* Write the unaligned first byte */
+        EEPROM_WriteDataByte((uintptr_t)dest++, *src++);
+        --len;
+    }
+
+    uint16_t value;
+    bool     aligned = ((uintptr_t)src % 2 == 0);
+    while (len > 1) {
+        if (aligned) {
+            value = *(uint16_t *)src;
+        } else {
+            value = *(uint8_t *)src | (*(uint8_t *)(src + 1) << 8);
+        }
+        EEPROM_WriteDataWord((uintptr_t)((uint16_t *)dest), value);
+        dest += 2;
+        src += 2;
+        len -= 2;
+    }
+
+    if (len) {
+        EEPROM_WriteDataByte((uintptr_t)dest, *src);
+    }
+}
diff --git a/platforms/chibios/drivers/eeprom/eeprom_stm32.h b/platforms/chibios/drivers/eeprom/eeprom_stm32.h
new file mode 100644
index 0000000000..8fcfb556b8
--- /dev/null
+++ b/platforms/chibios/drivers/eeprom/eeprom_stm32.h
@@ -0,0 +1,33 @@
+/*
+ * This software is experimental and a work in progress.
+ * Under no circumstances should these files be used in relation to any critical system(s).
+ * Use of these files is at your own risk.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+ * PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * This files are free to use from http://engsta.com/stm32-flash-memory-eeprom-emulator/ by
+ * Artur F.
+ *
+ * Modifications for QMK and STM32F303 by Yiancar
+ *
+ * This library assumes 8-bit data locations. To add a new MCU, please provide the flash
+ * page size and the total flash size in Kb. The number of available pages must be a multiple
+ * of 2. Only half of the pages account for the total EEPROM size.
+ * This library also assumes that the pages are not used by the firmware.
+ */
+
+#pragma once
+
+uint16_t EEPROM_Init(void);
+void     EEPROM_Erase(void);
+uint8_t  EEPROM_WriteDataByte(uint16_t Address, uint8_t DataByte);
+uint8_t  EEPROM_WriteDataWord(uint16_t Address, uint16_t DataWord);
+uint8_t  EEPROM_ReadDataByte(uint16_t Address);
+uint16_t EEPROM_ReadDataWord(uint16_t Address);
+
+void print_eeprom(void);
diff --git a/platforms/chibios/drivers/eeprom/eeprom_stm32_defs.h b/platforms/chibios/drivers/eeprom/eeprom_stm32_defs.h
new file mode 100644
index 0000000000..57d0440330
--- /dev/null
+++ b/platforms/chibios/drivers/eeprom/eeprom_stm32_defs.h
@@ -0,0 +1,136 @@
+/* Copyright 2021 QMK
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <hal.h>
+
+#if !defined(FEE_PAGE_SIZE) || !defined(FEE_PAGE_COUNT)
+#    if defined(STM32F103xB) || defined(STM32F042x6) || defined(GD32VF103C8) || defined(GD32VF103CB)
+#        ifndef FEE_PAGE_SIZE
+#            define FEE_PAGE_SIZE 0x400 // Page size = 1KByte
+#        endif
+#        ifndef FEE_PAGE_COUNT
+#            define FEE_PAGE_COUNT 2 // How many pages are used
+#        endif
+#    elif defined(STM32F103xE) || defined(STM32F303xC) || defined(STM32F303xE) || defined(STM32F072xB) || defined(STM32F070xB)
+#        ifndef FEE_PAGE_SIZE
+#            define FEE_PAGE_SIZE 0x800 // Page size = 2KByte
+#        endif
+#        ifndef FEE_PAGE_COUNT
+#            define FEE_PAGE_COUNT 4 // How many pages are used
+#        endif
+#    elif defined(STM32F401xC) || defined(STM32F401xE) || defined(STM32F405xG) || defined(STM32F411xE)
+#        ifndef FEE_PAGE_SIZE
+#            define FEE_PAGE_SIZE 0x4000 // Page size = 16KByte
+#        endif
+#        ifndef FEE_PAGE_COUNT
+#            define FEE_PAGE_COUNT 1 // How many pages are used
+#        endif
+#    endif
+#endif
+
+#if !defined(FEE_MCU_FLASH_SIZE)
+#    if defined(STM32F042x6)
+#        define FEE_MCU_FLASH_SIZE 32 // Size in Kb
+#    elif defined(GD32VF103C8)
+#        define FEE_MCU_FLASH_SIZE 64 // Size in Kb
+#    elif defined(STM32F103xB) || defined(STM32F072xB) || defined(STM32F070xB) || defined(GD32VF103CB)
+#        define FEE_MCU_FLASH_SIZE 128 // Size in Kb
+#    elif defined(STM32F303xC) || defined(STM32F401xC)
+#        define FEE_MCU_FLASH_SIZE 256 // Size in Kb
+#    elif defined(STM32F103xE) || defined(STM32F303xE) || defined(STM32F401xE) || defined(STM32F411xE)
+#        define FEE_MCU_FLASH_SIZE 512 // Size in Kb
+#    elif defined(STM32F405xG)
+#        define FEE_MCU_FLASH_SIZE 1024 // Size in Kb
+#    endif
+#endif
+
+/* Start of the emulated eeprom */
+#if !defined(FEE_PAGE_BASE_ADDRESS)
+#    if defined(STM32F401xC) || defined(STM32F401xE) || defined(STM32F405xG) || defined(STM32F411xE)
+#        ifndef FEE_PAGE_BASE_ADDRESS
+#            define FEE_PAGE_BASE_ADDRESS 0x08004000 // bodge to force 2nd 16k page
+#        endif
+#    else
+#        ifndef FEE_FLASH_BASE
+#            define FEE_FLASH_BASE 0x8000000
+#        endif
+/* Default to end of flash */
+#        define FEE_PAGE_BASE_ADDRESS ((uintptr_t)(FEE_FLASH_BASE) + FEE_MCU_FLASH_SIZE * 1024 - (FEE_PAGE_COUNT * FEE_PAGE_SIZE))
+#    endif
+#endif
+
+/* Addressable range 16KByte: 0 <-> (0x1FFF << 1) */
+#define FEE_ADDRESS_MAX_SIZE 0x4000
+
+/* Size of combined compacted eeprom and write log pages */
+#define FEE_DENSITY_MAX_SIZE (FEE_PAGE_COUNT * FEE_PAGE_SIZE)
+
+#ifndef FEE_MCU_FLASH_SIZE_IGNORE_CHECK /* *TODO: Get rid of this check */
+#    if FEE_DENSITY_MAX_SIZE > (FEE_MCU_FLASH_SIZE * 1024)
+#        pragma message STR(FEE_DENSITY_MAX_SIZE) " > " STR(FEE_MCU_FLASH_SIZE * 1024)
+#        error emulated eeprom: FEE_DENSITY_MAX_SIZE is greater than available flash size
+#    endif
+#endif
+
+/* Size of emulated eeprom */
+#ifdef FEE_DENSITY_BYTES
+#    if (FEE_DENSITY_BYTES > FEE_DENSITY_MAX_SIZE)
+#        pragma message STR(FEE_DENSITY_BYTES) " > " STR(FEE_DENSITY_MAX_SIZE)
+#        error emulated eeprom: FEE_DENSITY_BYTES exceeds FEE_DENSITY_MAX_SIZE
+#    endif
+#    if (FEE_DENSITY_BYTES == FEE_DENSITY_MAX_SIZE)
+#        pragma message STR(FEE_DENSITY_BYTES) " == " STR(FEE_DENSITY_MAX_SIZE)
+#        warning emulated eeprom: FEE_DENSITY_BYTES leaves no room for a write log.  This will greatly increase the flash wear rate!
+#    endif
+#    if FEE_DENSITY_BYTES > FEE_ADDRESS_MAX_SIZE
+#        pragma message STR(FEE_DENSITY_BYTES) " > " STR(FEE_ADDRESS_MAX_SIZE)
+#        error emulated eeprom: FEE_DENSITY_BYTES is greater than FEE_ADDRESS_MAX_SIZE allows
+#    endif
+#    if ((FEE_DENSITY_BYTES) % 2) == 1
+#        error emulated eeprom: FEE_DENSITY_BYTES must be even
+#    endif
+#else
+/* Default to half of allocated space used for emulated eeprom, half for write log */
+#    define FEE_DENSITY_BYTES (FEE_PAGE_COUNT * FEE_PAGE_SIZE / 2)
+#endif
+
+/* Size of write log */
+#ifdef FEE_WRITE_LOG_BYTES
+#    if ((FEE_DENSITY_BYTES + FEE_WRITE_LOG_BYTES) > FEE_DENSITY_MAX_SIZE)
+#        pragma message STR(FEE_DENSITY_BYTES) " + " STR(FEE_WRITE_LOG_BYTES) " > " STR(FEE_DENSITY_MAX_SIZE)
+#        error emulated eeprom: FEE_WRITE_LOG_BYTES exceeds remaining FEE_DENSITY_MAX_SIZE
+#    endif
+#    if ((FEE_WRITE_LOG_BYTES) % 2) == 1
+#        error emulated eeprom: FEE_WRITE_LOG_BYTES must be even
+#    endif
+#else
+/* Default to use all remaining space */
+#    define FEE_WRITE_LOG_BYTES (FEE_PAGE_COUNT * FEE_PAGE_SIZE - FEE_DENSITY_BYTES)
+#endif
+
+/* Start of the emulated eeprom compacted flash area */
+#define FEE_COMPACTED_BASE_ADDRESS FEE_PAGE_BASE_ADDRESS
+/* End of the emulated eeprom compacted flash area */
+#define FEE_COMPACTED_LAST_ADDRESS (FEE_COMPACTED_BASE_ADDRESS + FEE_DENSITY_BYTES)
+/* Start of the emulated eeprom write log */
+#define FEE_WRITE_LOG_BASE_ADDRESS FEE_COMPACTED_LAST_ADDRESS
+/* End of the emulated eeprom write log */
+#define FEE_WRITE_LOG_LAST_ADDRESS (FEE_WRITE_LOG_BASE_ADDRESS + FEE_WRITE_LOG_BYTES)
+
+#if defined(DYNAMIC_KEYMAP_EEPROM_MAX_ADDR) && (DYNAMIC_KEYMAP_EEPROM_MAX_ADDR >= FEE_DENSITY_BYTES)
+#    error emulated eeprom: DYNAMIC_KEYMAP_EEPROM_MAX_ADDR is greater than the FEE_DENSITY_BYTES available
+#endif
diff --git a/platforms/chibios/drivers/eeprom/eeprom_teensy.c b/platforms/chibios/drivers/eeprom/eeprom_teensy.c
new file mode 100644
index 0000000000..c8777febde
--- /dev/null
+++ b/platforms/chibios/drivers/eeprom/eeprom_teensy.c
@@ -0,0 +1,546 @@
+#include <ch.h>
+#include <hal.h>
+
+#include "eeprom_teensy.h"
+#include "eeconfig.h"
+
+/*************************************/
+/*          Hardware backend         */
+/*                                   */
+/*    Code from PJRC/Teensyduino     */
+/*************************************/
+
+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2013 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#if defined(K20x) /* chip selection */
+/* Teensy 3.0, 3.1, 3.2; mchck; infinity keyboard */
+
+/*
+    ^^^ Here be dragons:
+        NXP AppNote AN4282 section 3.1 states that partitioning must only be done once.
+        Once EEPROM partitioning is done, the size is locked to this initial configuration.
+        Attempts to modify the EEPROM_SIZE setting may brick your board.
+*/
+
+// Writing unaligned 16 or 32 bit data is handled automatically when
+// this is defined, but at a cost of extra code size.  Without this,
+// any unaligned write will cause a hard fault exception!  If you're
+// absolutely sure all 16 and 32 bit writes will be aligned, you can
+// remove the extra unnecessary code.
+//
+#    define HANDLE_UNALIGNED_WRITES
+
+// Minimum EEPROM Endurance
+// ------------------------
+#    if (EEPROM_SIZE == 2048) // 35000 writes/byte or 70000 writes/word
+#        define EEESIZE 0x33
+#    elif (EEPROM_SIZE == 1024) // 75000 writes/byte or 150000 writes/word
+#        define EEESIZE 0x34
+#    elif (EEPROM_SIZE == 512) // 155000 writes/byte or 310000 writes/word
+#        define EEESIZE 0x35
+#    elif (EEPROM_SIZE == 256) // 315000 writes/byte or 630000 writes/word
+#        define EEESIZE 0x36
+#    elif (EEPROM_SIZE == 128) // 635000 writes/byte or 1270000 writes/word
+#        define EEESIZE 0x37
+#    elif (EEPROM_SIZE == 64) // 1275000 writes/byte or 2550000 writes/word
+#        define EEESIZE 0x38
+#    elif (EEPROM_SIZE == 32) // 2555000 writes/byte or 5110000 writes/word
+#        define EEESIZE 0x39
+#    endif
+
+/** \brief eeprom initialization
+ *
+ * FIXME: needs doc
+ */
+void eeprom_initialize(void) {
+    uint32_t count          = 0;
+    uint16_t do_flash_cmd[] = {0xf06f, 0x037f, 0x7003, 0x7803, 0xf013, 0x0f80, 0xd0fb, 0x4770};
+    uint8_t  status;
+
+    if (FTFL->FCNFG & FTFL_FCNFG_RAMRDY) {
+        // FlexRAM is configured as traditional RAM
+        // We need to reconfigure for EEPROM usage
+        FTFL->FCCOB0 = 0x80;    // PGMPART = Program Partition Command
+        FTFL->FCCOB4 = EEESIZE; // EEPROM Size
+        FTFL->FCCOB5 = 0x03;    // 0K for Dataflash, 32K for EEPROM backup
+        __disable_irq();
+        // do_flash_cmd() must execute from RAM.  Luckily the C syntax is simple...
+        (*((void (*)(volatile uint8_t *))((uint32_t)do_flash_cmd | 1)))(&(FTFL->FSTAT));
+        __enable_irq();
+        status = FTFL->FSTAT;
+        if (status & (FTFL_FSTAT_RDCOLERR | FTFL_FSTAT_ACCERR | FTFL_FSTAT_FPVIOL)) {
+            FTFL->FSTAT = (status & (FTFL_FSTAT_RDCOLERR | FTFL_FSTAT_ACCERR | FTFL_FSTAT_FPVIOL));
+            return; // error
+        }
+    }
+    // wait for eeprom to become ready (is this really necessary?)
+    while (!(FTFL->FCNFG & FTFL_FCNFG_EEERDY)) {
+        if (++count > 20000) break;
+    }
+}
+
+#    define FlexRAM ((uint8_t *)0x14000000)
+
+/** \brief eeprom read byte
+ *
+ * FIXME: needs doc
+ */
+uint8_t eeprom_read_byte(const uint8_t *addr) {
+    uint32_t offset = (uint32_t)addr;
+    if (offset >= EEPROM_SIZE) return 0;
+    if (!(FTFL->FCNFG & FTFL_FCNFG_EEERDY)) eeprom_initialize();
+    return FlexRAM[offset];
+}
+
+/** \brief eeprom read word
+ *
+ * FIXME: needs doc
+ */
+uint16_t eeprom_read_word(const uint16_t *addr) {
+    uint32_t offset = (uint32_t)addr;
+    if (offset >= EEPROM_SIZE - 1) return 0;
+    if (!(FTFL->FCNFG & FTFL_FCNFG_EEERDY)) eeprom_initialize();
+    return *(uint16_t *)(&FlexRAM[offset]);
+}
+
+/** \brief eeprom read dword
+ *
+ * FIXME: needs doc
+ */
+uint32_t eeprom_read_dword(const uint32_t *addr) {
+    uint32_t offset = (uint32_t)addr;
+    if (offset >= EEPROM_SIZE - 3) return 0;
+    if (!(FTFL->FCNFG & FTFL_FCNFG_EEERDY)) eeprom_initialize();
+    return *(uint32_t *)(&FlexRAM[offset]);
+}
+
+/** \brief eeprom read block
+ *
+ * FIXME: needs doc
+ */
+void eeprom_read_block(void *buf, const void *addr, uint32_t len) {
+    uint32_t offset = (uint32_t)addr;
+    uint8_t *dest   = (uint8_t *)buf;
+    uint32_t end    = offset + len;
+
+    if (!(FTFL->FCNFG & FTFL_FCNFG_EEERDY)) eeprom_initialize();
+    if (end > EEPROM_SIZE) end = EEPROM_SIZE;
+    while (offset < end) {
+        *dest++ = FlexRAM[offset++];
+    }
+}
+
+/** \brief eeprom is ready
+ *
+ * FIXME: needs doc
+ */
+int eeprom_is_ready(void) {
+    return (FTFL->FCNFG & FTFL_FCNFG_EEERDY) ? 1 : 0;
+}
+
+/** \brief flexram wait
+ *
+ * FIXME: needs doc
+ */
+static void flexram_wait(void) {
+    while (!(FTFL->FCNFG & FTFL_FCNFG_EEERDY)) {
+        // TODO: timeout
+    }
+}
+
+/** \brief eeprom_write_byte
+ *
+ * FIXME: needs doc
+ */
+void eeprom_write_byte(uint8_t *addr, uint8_t value) {
+    uint32_t offset = (uint32_t)addr;
+
+    if (offset >= EEPROM_SIZE) return;
+    if (!(FTFL->FCNFG & FTFL_FCNFG_EEERDY)) eeprom_initialize();
+    if (FlexRAM[offset] != value) {
+        FlexRAM[offset] = value;
+        flexram_wait();
+    }
+}
+
+/** \brief eeprom write word
+ *
+ * FIXME: needs doc
+ */
+void eeprom_write_word(uint16_t *addr, uint16_t value) {
+    uint32_t offset = (uint32_t)addr;
+
+    if (offset >= EEPROM_SIZE - 1) return;
+    if (!(FTFL->FCNFG & FTFL_FCNFG_EEERDY)) eeprom_initialize();
+#    ifdef HANDLE_UNALIGNED_WRITES
+    if ((offset & 1) == 0) {
+#    endif
+        if (*(uint16_t *)(&FlexRAM[offset]) != value) {
+            *(uint16_t *)(&FlexRAM[offset]) = value;
+            flexram_wait();
+        }
+#    ifdef HANDLE_UNALIGNED_WRITES
+    } else {
+        if (FlexRAM[offset] != value) {
+            FlexRAM[offset] = value;
+            flexram_wait();
+        }
+        if (FlexRAM[offset + 1] != (value >> 8)) {
+            FlexRAM[offset + 1] = value >> 8;
+            flexram_wait();
+        }
+    }
+#    endif
+}
+
+/** \brief eeprom write dword
+ *
+ * FIXME: needs doc
+ */
+void eeprom_write_dword(uint32_t *addr, uint32_t value) {
+    uint32_t offset = (uint32_t)addr;
+
+    if (offset >= EEPROM_SIZE - 3) return;
+    if (!(FTFL->FCNFG & FTFL_FCNFG_EEERDY)) eeprom_initialize();
+#    ifdef HANDLE_UNALIGNED_WRITES
+    switch (offset & 3) {
+        case 0:
+#    endif
+            if (*(uint32_t *)(&FlexRAM[offset]) != value) {
+                *(uint32_t *)(&FlexRAM[offset]) = value;
+                flexram_wait();
+            }
+            return;
+#    ifdef HANDLE_UNALIGNED_WRITES
+        case 2:
+            if (*(uint16_t *)(&FlexRAM[offset]) != value) {
+                *(uint16_t *)(&FlexRAM[offset]) = value;
+                flexram_wait();
+            }
+            if (*(uint16_t *)(&FlexRAM[offset + 2]) != (value >> 16)) {
+                *(uint16_t *)(&FlexRAM[offset + 2]) = value >> 16;
+                flexram_wait();
+            }
+            return;
+        default:
+            if (FlexRAM[offset] != value) {
+                FlexRAM[offset] = value;
+                flexram_wait();
+            }
+            if (*(uint16_t *)(&FlexRAM[offset + 1]) != (value >> 8)) {
+                *(uint16_t *)(&FlexRAM[offset + 1]) = value >> 8;
+                flexram_wait();
+            }
+            if (FlexRAM[offset + 3] != (value >> 24)) {
+                FlexRAM[offset + 3] = value >> 24;
+                flexram_wait();
+            }
+    }
+#    endif
+}
+
+/** \brief eeprom write block
+ *
+ * FIXME: needs doc
+ */
+void eeprom_write_block(const void *buf, void *addr, uint32_t len) {
+    uint32_t       offset = (uint32_t)addr;
+    const uint8_t *src    = (const uint8_t *)buf;
+
+    if (offset >= EEPROM_SIZE) return;
+    if (!(FTFL->FCNFG & FTFL_FCNFG_EEERDY)) eeprom_initialize();
+    if (len >= EEPROM_SIZE) len = EEPROM_SIZE;
+    if (offset + len >= EEPROM_SIZE) len = EEPROM_SIZE - offset;
+    while (len > 0) {
+        uint32_t lsb = offset & 3;
+        if (lsb == 0 && len >= 4) {
+            // write aligned 32 bits
+            uint32_t val32;
+            val32 = *src++;
+            val32 |= (*src++ << 8);
+            val32 |= (*src++ << 16);
+            val32 |= (*src++ << 24);
+            if (*(uint32_t *)(&FlexRAM[offset]) != val32) {
+                *(uint32_t *)(&FlexRAM[offset]) = val32;
+                flexram_wait();
+            }
+            offset += 4;
+            len -= 4;
+        } else if ((lsb == 0 || lsb == 2) && len >= 2) {
+            // write aligned 16 bits
+            uint16_t val16;
+            val16 = *src++;
+            val16 |= (*src++ << 8);
+            if (*(uint16_t *)(&FlexRAM[offset]) != val16) {
+                *(uint16_t *)(&FlexRAM[offset]) = val16;
+                flexram_wait();
+            }
+            offset += 2;
+            len -= 2;
+        } else {
+            // write 8 bits
+            uint8_t val8 = *src++;
+            if (FlexRAM[offset] != val8) {
+                FlexRAM[offset] = val8;
+                flexram_wait();
+            }
+            offset++;
+            len--;
+        }
+    }
+}
+
+/*
+void do_flash_cmd(volatile uint8_t *fstat)
+{
+    *fstat = 0x80;
+    while ((*fstat & 0x80) == 0) ; // wait
+}
+00000000 <do_flash_cmd>:
+   0:	f06f 037f 	mvn.w	r3, #127	; 0x7f
+   4:	7003      	strb	r3, [r0, #0]
+   6:	7803      	ldrb	r3, [r0, #0]
+   8:	f013 0f80 	tst.w	r3, #128	; 0x80
+   c:	d0fb      	beq.n	6 <do_flash_cmd+0x6>
+   e:	4770      	bx	lr
+*/
+
+#elif defined(KL2x) /* chip selection */
+/* Teensy LC (emulated) */
+
+#    define SYMVAL(sym) (uint32_t)(((uint8_t *)&(sym)) - ((uint8_t *)0))
+
+extern uint32_t __eeprom_workarea_start__;
+extern uint32_t __eeprom_workarea_end__;
+
+static uint32_t flashend = 0;
+
+void eeprom_initialize(void) {
+    const uint16_t *p = (uint16_t *)SYMVAL(__eeprom_workarea_start__);
+
+    do {
+        if (*p++ == 0xFFFF) {
+            flashend = (uint32_t)(p - 2);
+            return;
+        }
+    } while (p < (uint16_t *)SYMVAL(__eeprom_workarea_end__));
+    flashend = (uint32_t)(p - 1);
+}
+
+uint8_t eeprom_read_byte(const uint8_t *addr) {
+    uint32_t        offset = (uint32_t)addr;
+    const uint16_t *p      = (uint16_t *)SYMVAL(__eeprom_workarea_start__);
+    const uint16_t *end    = (const uint16_t *)((uint32_t)flashend);
+    uint16_t        val;
+    uint8_t         data = 0xFF;
+
+    if (!end) {
+        eeprom_initialize();
+        end = (const uint16_t *)((uint32_t)flashend);
+    }
+    if (offset < EEPROM_SIZE) {
+        while (p <= end) {
+            val = *p++;
+            if ((val & 255) == offset) data = val >> 8;
+        }
+    }
+    return data;
+}
+
+static void flash_write(const uint16_t *code, uint32_t addr, uint32_t data) {
+    // with great power comes great responsibility....
+    uint32_t stat;
+    *(uint32_t *)&(FTFA->FCCOB3) = 0x06000000 | (addr & 0x00FFFFFC);
+    *(uint32_t *)&(FTFA->FCCOB7) = data;
+    __disable_irq();
+    (*((void (*)(volatile uint8_t *))((uint32_t)code | 1)))(&(FTFA->FSTAT));
+    __enable_irq();
+    stat = FTFA->FSTAT & (FTFA_FSTAT_RDCOLERR | FTFA_FSTAT_ACCERR | FTFA_FSTAT_FPVIOL);
+    if (stat) {
+        FTFA->FSTAT = stat;
+    }
+    MCM->PLACR |= MCM_PLACR_CFCC;
+}
+
+void eeprom_write_byte(uint8_t *addr, uint8_t data) {
+    uint32_t        offset = (uint32_t)addr;
+    const uint16_t *p, *end = (const uint16_t *)((uint32_t)flashend);
+    uint32_t        i, val, flashaddr;
+    uint16_t        do_flash_cmd[] = {0x2380, 0x7003, 0x7803, 0xb25b, 0x2b00, 0xdafb, 0x4770};
+    uint8_t         buf[EEPROM_SIZE];
+
+    if (offset >= EEPROM_SIZE) return;
+    if (!end) {
+        eeprom_initialize();
+        end = (const uint16_t *)((uint32_t)flashend);
+    }
+    if (++end < (uint16_t *)SYMVAL(__eeprom_workarea_end__)) {
+        val       = (data << 8) | offset;
+        flashaddr = (uint32_t)end;
+        flashend  = flashaddr;
+        if ((flashaddr & 2) == 0) {
+            val |= 0xFFFF0000;
+        } else {
+            val <<= 16;
+            val |= 0x0000FFFF;
+        }
+        flash_write(do_flash_cmd, flashaddr, val);
+    } else {
+        for (i = 0; i < EEPROM_SIZE; i++) {
+            buf[i] = 0xFF;
+        }
+        val = 0;
+        for (p = (uint16_t *)SYMVAL(__eeprom_workarea_start__); p < (uint16_t *)SYMVAL(__eeprom_workarea_end__); p++) {
+            val = *p;
+            if ((val & 255) < EEPROM_SIZE) {
+                buf[val & 255] = val >> 8;
+            }
+        }
+        buf[offset] = data;
+        for (flashaddr = (uint32_t)(uint16_t *)SYMVAL(__eeprom_workarea_start__); flashaddr < (uint32_t)(uint16_t *)SYMVAL(__eeprom_workarea_end__); flashaddr += 1024) {
+            *(uint32_t *)&(FTFA->FCCOB3) = 0x09000000 | flashaddr;
+            __disable_irq();
+            (*((void (*)(volatile uint8_t *))((uint32_t)do_flash_cmd | 1)))(&(FTFA->FSTAT));
+            __enable_irq();
+            val = FTFA->FSTAT & (FTFA_FSTAT_RDCOLERR | FTFA_FSTAT_ACCERR | FTFA_FSTAT_FPVIOL);
+            ;
+            if (val) FTFA->FSTAT = val;
+            MCM->PLACR |= MCM_PLACR_CFCC;
+        }
+        flashaddr = (uint32_t)(uint16_t *)SYMVAL(__eeprom_workarea_start__);
+        for (i = 0; i < EEPROM_SIZE; i++) {
+            if (buf[i] == 0xFF) continue;
+            if ((flashaddr & 2) == 0) {
+                val = (buf[i] << 8) | i;
+            } else {
+                val = val | (buf[i] << 24) | (i << 16);
+                flash_write(do_flash_cmd, flashaddr, val);
+            }
+            flashaddr += 2;
+        }
+        flashend = flashaddr;
+        if ((flashaddr & 2)) {
+            val |= 0xFFFF0000;
+            flash_write(do_flash_cmd, flashaddr, val);
+        }
+    }
+}
+
+/*
+void do_flash_cmd(volatile uint8_t *fstat)
+{
+        *fstat = 0x80;
+        while ((*fstat & 0x80) == 0) ; // wait
+}
+00000000 <do_flash_cmd>:
+   0:	2380      	movs	r3, #128	; 0x80
+   2:	7003      	strb	r3, [r0, #0]
+   4:	7803      	ldrb	r3, [r0, #0]
+   6:	b25b      	sxtb	r3, r3
+   8:	2b00      	cmp	r3, #0
+   a:	dafb      	bge.n	4 <do_flash_cmd+0x4>
+   c:	4770      	bx	lr
+*/
+
+uint16_t eeprom_read_word(const uint16_t *addr) {
+    const uint8_t *p = (const uint8_t *)addr;
+    return eeprom_read_byte(p) | (eeprom_read_byte(p + 1) << 8);
+}
+
+uint32_t eeprom_read_dword(const uint32_t *addr) {
+    const uint8_t *p = (const uint8_t *)addr;
+    return eeprom_read_byte(p) | (eeprom_read_byte(p + 1) << 8) | (eeprom_read_byte(p + 2) << 16) | (eeprom_read_byte(p + 3) << 24);
+}
+
+void eeprom_read_block(void *buf, const void *addr, uint32_t len) {
+    const uint8_t *p    = (const uint8_t *)addr;
+    uint8_t *      dest = (uint8_t *)buf;
+    while (len--) {
+        *dest++ = eeprom_read_byte(p++);
+    }
+}
+
+int eeprom_is_ready(void) {
+    return 1;
+}
+
+void eeprom_write_word(uint16_t *addr, uint16_t value) {
+    uint8_t *p = (uint8_t *)addr;
+    eeprom_write_byte(p++, value);
+    eeprom_write_byte(p, value >> 8);
+}
+
+void eeprom_write_dword(uint32_t *addr, uint32_t value) {
+    uint8_t *p = (uint8_t *)addr;
+    eeprom_write_byte(p++, value);
+    eeprom_write_byte(p++, value >> 8);
+    eeprom_write_byte(p++, value >> 16);
+    eeprom_write_byte(p, value >> 24);
+}
+
+void eeprom_write_block(const void *buf, void *addr, uint32_t len) {
+    uint8_t *      p   = (uint8_t *)addr;
+    const uint8_t *src = (const uint8_t *)buf;
+    while (len--) {
+        eeprom_write_byte(p++, *src++);
+    }
+}
+
+#else
+#    error Unsupported Teensy EEPROM.
+#endif /* chip selection */
+// The update functions just calls write for now, but could probably be optimized
+
+void eeprom_update_byte(uint8_t *addr, uint8_t value) {
+    eeprom_write_byte(addr, value);
+}
+
+void eeprom_update_word(uint16_t *addr, uint16_t value) {
+    uint8_t *p = (uint8_t *)addr;
+    eeprom_write_byte(p++, value);
+    eeprom_write_byte(p, value >> 8);
+}
+
+void eeprom_update_dword(uint32_t *addr, uint32_t value) {
+    uint8_t *p = (uint8_t *)addr;
+    eeprom_write_byte(p++, value);
+    eeprom_write_byte(p++, value >> 8);
+    eeprom_write_byte(p++, value >> 16);
+    eeprom_write_byte(p, value >> 24);
+}
+
+void eeprom_update_block(const void *buf, void *addr, size_t len) {
+    uint8_t *      p   = (uint8_t *)addr;
+    const uint8_t *src = (const uint8_t *)buf;
+    while (len--) {
+        eeprom_write_byte(p++, *src++);
+    }
+}
diff --git a/platforms/chibios/drivers/eeprom/eeprom_teensy.h b/platforms/chibios/drivers/eeprom/eeprom_teensy.h
new file mode 100755
index 0000000000..9a14a1fa79
--- /dev/null
+++ b/platforms/chibios/drivers/eeprom/eeprom_teensy.h
@@ -0,0 +1,25 @@
+// Copyright 2022 Nick Brassel (@tzarc)
+// SPDX-License-Identifier: GPL-2.0-or-later
+#pragma once
+
+#include <ch.h>
+#include <hal.h>
+
+#if defined(K20x)
+/* Teensy 3.0, 3.1, 3.2; mchck; infinity keyboard */
+// The EEPROM is really RAM with a hardware-based backup system to
+// flash memory.  Selecting a smaller size EEPROM allows more wear
+// leveling, for higher write endurance.  If you edit this file,
+// set this to the smallest size your application can use.  Also,
+// due to Freescale's implementation, writing 16 or 32 bit words
+// (aligned to 2 or 4 byte boundaries) has twice the endurance
+// compared to writing 8 bit bytes.
+//
+#    ifndef EEPROM_SIZE
+#        define EEPROM_SIZE 32
+#    endif
+#elif defined(KL2x) /* Teensy LC (emulated) */
+#    define EEPROM_SIZE 128
+#else
+#    error Unsupported Teensy EEPROM.
+#endif