fw-rust: Refactor everything

Remove avr-eeprom dependency for now and introduce events.

firmware/rust/src/eeprom.rs

@@ -0,0 +1,48 @@
+use atmega_hal::Peripherals;
+use avr_device::interrupt;
+use core::convert::Infallible;
+use nb::Error::WouldBlock;
+
+pub fn read_byte(p_addr: *const u8) -> nb::Result<u8, Infallible> {
+    let dp = unsafe { Peripherals::steal() };
+    let eeprom = dp.EEPROM;
+
+    // Wait for completion of previous access
+    if eeprom.eecr.read().eepe().bit_is_set() {
+        return Err(WouldBlock);
+    }
+
+    interrupt::free(|_cs| {
+        // Write address into EEPROM address register
+        eeprom.eear.write(|w| unsafe { w.bits(p_addr as u16) });
+        // Start to read from EEPROM by setting EERE
+        eeprom.eecr.write(|w| w.eere().set_bit());
+    });
+
+    // Return data from EEPROM data register
+    Ok(eeprom.eedr.read().bits())
+}
+
+pub fn write_byte(p_addr: *const u8, data: u8) -> nb::Result<(), Infallible> {
+    let dp = unsafe { Peripherals::steal() };
+    let eeprom = dp.EEPROM;
+
+    // Wait for completion of previous access
+    if eeprom.eecr.read().eepe().bit_is_set() {
+        return Err(WouldBlock);
+    }
+
+    interrupt::free(|_cs| {
+        // Write address into EEPROM address register
+        eeprom.eear.write(|w| unsafe { w.bits(p_addr as u16) });
+        // Write data into EEPROM data register
+        eeprom.eedr.write(|w| unsafe { w.bits(data) });
+        // Enable writing to the EEPROM by setting EEMPE
+        eeprom.eecr.write(|w| w.eempe().set_bit());
+        // Start to write to EEPROM by setting EEPE
+        eeprom.eecr.write(|w| w.eepe().set_bit());
+    });
+
+    // Return data from EEPROM data register
+    Ok(())
+}