--- /dev/null
+/*
+ * Copyright © 2024 Keith Packard <keithp@keithp.com>
+ *
+ * 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, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao.h>
+#include <ao_flash.h>
+
+extern uint8_t __eeprom_base[2048];
+
+uint8_t
+ao_eeprom_read(ao_pos_t pos, void *v, uint16_t len)
+{
+ memcpy(v, &__eeprom_base[pos], len);
+ return 1;
+}
+
+uint8_t
+ao_eeprom_write(ao_pos_t pos, void *v, uint16_t len)
+{
+ bool hsi_on = (stm_rcc.cr & (1UL << STM_RCC_CR_HSIRDY)) != 0;
+
+ if (!hsi_on) {
+ stm_rcc.cr |= (1UL << STM_RCC_CR_HSION);
+ while (!(stm_rcc.cr & (1 << STM_RCC_CR_HSIRDY)))
+ ao_arch_nop();
+
+ }
+ ao_flash_bytes(&__eeprom_base[pos], v, len);
+
+ if (!hsi_on) {
+ stm_rcc.cr &= ~(1UL << STM_RCC_CR_HSION);
+ }
+
+ return 1;
+}
+