1 files changed, 120 insertions, 0 deletions
diff --git a/drivers/eeprom/eeprom_i2c.c b/drivers/eeprom/eeprom_i2c.c
new file mode 100644
index 000000000..03dbc5e51
--- /dev/null
+++ b/drivers/eeprom/eeprom_i2c.c
@@ -0,0 +1,120 @@
+/* Copyright 2019 Nick Brassel (tzarc)
+ *
+ * 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 2 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/>.
+ */
+
+#include <stdint.h>
+#include <string.h>
+
+/*
+    Note that the implementations of eeprom_XXXX_YYYY on AVR are normally
+    provided by avr-libc. The same functions are reimplemented below and are
+    rerouted to the external i2c equivalent.
+
+    Seemingly, as this is compiled from within QMK, the object file generated
+    during the build overrides the avr-libc implementation during the linking
+    stage.
+
+    On other platforms such as ARM, there are no provided implementations, so
+    there is nothing to override during linkage.
+*/
+
+#include "wait.h"
+#include "i2c_master.h"
+#include "eeprom.h"
+#include "eeprom_i2c.h"
+
+// #define DEBUG_EEPROM_OUTPUT
+
+#ifdef DEBUG_EEPROM_OUTPUT
+#    include "print.h"
+#endif  // DEBUG_EEPROM_OUTPUT
+
+static inline void init_i2c_if_required(void) {
+    static int done = 0;
+    if (!done) {
+        i2c_init();
+        done = 1;
+    }
+}
+
+static inline void fill_target_address(uint8_t *buffer, const void *addr) {
+    intptr_t p = (intptr_t)addr;
+    for (int i = 0; i < EXTERNAL_EEPROM_ADDRESS_SIZE; ++i) {
+        buffer[EXTERNAL_EEPROM_ADDRESS_SIZE - 1 - i] = p & 0xFF;
+        p >>= 8;
+    }
+}
+
+void eeprom_driver_init(void) {}
+
+void eeprom_driver_erase(void) {
+    uint8_t buf[EXTERNAL_EEPROM_PAGE_SIZE];
+    memset(buf, 0x00, EXTERNAL_EEPROM_PAGE_SIZE);
+    for (intptr_t addr = 0; addr < EXTERNAL_EEPROM_BYTE_COUNT; addr += EXTERNAL_EEPROM_PAGE_SIZE) {
+        eeprom_write_block(buf, (void *)addr, EXTERNAL_EEPROM_PAGE_SIZE);
+    }
+}
+
+void eeprom_read_block(void *buf, const void *addr, size_t len) {
+    uint8_t complete_packet[EXTERNAL_EEPROM_ADDRESS_SIZE];
+    fill_target_address(complete_packet, addr);
+
+    init_i2c_if_required();
+    i2c_transmit(EXTERNAL_EEPROM_I2C_ADDRESS((intptr_t)addr), complete_packet, EXTERNAL_EEPROM_ADDRESS_SIZE, 100);
+    i2c_receive(EXTERNAL_EEPROM_I2C_ADDRESS((intptr_t)addr), buf, len, 100);
+
+#ifdef DEBUG_EEPROM_OUTPUT
+    dprintf("[EEPROM R] 0x%04X: ", ((int)addr));
+    for (size_t i = 0; i < len; ++i) {
+        dprintf(" %02X", (int)(((uint8_t *)buf)[i]));
+    }
+    dprintf("\n");
+#endif  // DEBUG_EEPROM_OUTPUT
+}
+
+void eeprom_write_block(const void *buf, void *addr, size_t len) {
+    uint8_t  complete_packet[EXTERNAL_EEPROM_ADDRESS_SIZE + EXTERNAL_EEPROM_PAGE_SIZE];
+    uint8_t *read_buf    = (uint8_t *)buf;
+    intptr_t target_addr = (intptr_t)addr;
+
+    init_i2c_if_required();
+    while (len > 0) {
+        intptr_t page_offset  = target_addr % EXTERNAL_EEPROM_PAGE_SIZE;
+        int      write_length = EXTERNAL_EEPROM_PAGE_SIZE - page_offset;
+        if (write_length > len) {
+            write_length = len;
+        }
+
+        fill_target_address(complete_packet, (const void *)target_addr);
+        for (uint8_t i = 0; i < write_length; i++) {
+            complete_packet[EXTERNAL_EEPROM_ADDRESS_SIZE + i] = read_buf[i];
+        }
+
+#ifdef DEBUG_EEPROM_OUTPUT
+        dprintf("[EEPROM W] 0x%04X: ", ((int)target_addr));
+        for (uint8_t i = 0; i < write_length; i++) {
+            dprintf(" %02X", (int)(read_buf[i]));
+        }
+        dprintf("\n");
+#endif  // DEBUG_EEPROM_OUTPUT
+
+        i2c_transmit(EXTERNAL_EEPROM_I2C_ADDRESS((intptr_t)addr), complete_packet, EXTERNAL_EEPROM_ADDRESS_SIZE + write_length, 100);
+        wait_ms(EXTERNAL_EEPROM_WRITE_TIME);
+
+        read_buf += write_length;
+        target_addr += write_length;
+        len -= write_length;
+    }
+}