Add customisable EEPROM driver selection (#7274)

- uprintf -> dprintf
- Fix atsam "vendor" eeprom.
- Bump Kinetis K20x to 64 bytes, too.
- Rollback Kinetis to 32 bytes as partitioning can only be done once. Add warning about changing the value.
- Change RAM-backed "fake" EEPROM implementations to match eeconfig's current usage.
- Add 24LC128 by request.

drivers/eeprom/eeprom_transient.c

@@ -0,0 +1,52 @@
+/* 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>
+
+#include "eeprom_driver.h"
+#include "eeprom_transient.h"
+
+__attribute__((aligned(4))) static uint8_t transientBuffer[TRANSIENT_EEPROM_SIZE] = {0};
+
+size_t clamp_length(intptr_t offset, size_t len) {
+    if (offset + len > TRANSIENT_EEPROM_SIZE) {
+        len = TRANSIENT_EEPROM_SIZE - offset;
+    }
+
+    return len;
+}
+
+void eeprom_driver_init(void) { eeprom_driver_erase(); }
+
+void eeprom_driver_erase(void) { memset(transientBuffer, 0x00, TRANSIENT_EEPROM_SIZE); }
+
+void eeprom_read_block(void *buf, const void *addr, size_t len) {
+    intptr_t offset = (intptr_t)addr;
+    memset(buf, 0x00, len);
+    len = clamp_length(offset, len);
+    if (len > 0) {
+        memcpy(buf, &transientBuffer[offset], len);
+    }
+}
+
+void eeprom_write_block(const void *buf, void *addr, size_t len) {
+    intptr_t offset = (intptr_t)addr;
+    len             = clamp_length(offset, len);
+    if (len > 0) {
+        memcpy(&transientBuffer[offset], buf, len);
+    }
+}