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#![no_std] #[cfg(test)] extern crate std; #[cfg(test)] mod tests; pub trait CommandHandler { fn handle_read_byte(&self) -> Option<u8>; fn handle_read_byte_data(&self, reg: u8) -> Option<u8>; fn handle_read_word_data(&self, reg: u8) -> Option<u16>; fn handle_read_block_data(&self, reg: u8, index: u8) -> Option<u8>; fn handle_write_byte(&mut self, data: u8) -> Result<(), ()>; fn handle_write_byte_data(&mut self, reg: u8, data: u8) -> Result<(), ()>; fn handle_write_word_data(&mut self, reg: u8, data: u16) -> Result<(), ()>; fn handle_write_block_data(&mut self, reg: u8, count: u8, block: &[u8]) -> Result<(), ()>; fn handle_i2c_event( &mut self, event: &mut I2CEvent, mut bus_state: &mut SMBusState, ) -> Result<(), SMBusProtocolError> { match event { I2CEvent::Initiated { direction } => bus_state.direction = Some(*direction), I2CEvent::ReceivedByte { byte } => { if bus_state.index >= RECEIVE_BUFFER_SIZE { let err = Err(SMBusProtocolError::InvalidWriteBound(bus_state.index - 2)); *bus_state = SMBusState::default(); return err; } bus_state.received_data[bus_state.index as usize] = *byte; bus_state.index += 1; } I2CEvent::RequestedByte { byte } => { if bus_state.direction != Some(Direction::SlaveToMaster) { return Err(SMBusProtocolError::WrongDirection(bus_state.direction)); } match bus_state.index { 0 => { if let Some(Direction::SlaveToMaster) = bus_state.direction { if let Some(data) = self.handle_read_byte() { **byte = data; } else { return Err(SMBusProtocolError::ReadByteUnsupported); } } else { return Err(SMBusProtocolError::WrongDirection(bus_state.direction)); } } 1 => { let register = bus_state.received_data[0]; if let Some(data) = self.handle_read_byte_data(register) { bus_state.current_transfer = Some(StatefulTransfer::ReadByte(data)); **byte = data; } else if let Some(data) = self.handle_read_word_data(register) { bus_state.current_transfer = Some(StatefulTransfer::ReadWord(data)); **byte = data as u8; } else if let Some(data) = self.handle_read_block_data(register, 0) { bus_state.current_transfer = Some(StatefulTransfer::ReadBlock(data)); **byte = data; } else { return Err(SMBusProtocolError::InvalidReadRegister(register)); } } 2 => { let first_byte = bus_state.received_data[0]; match bus_state.current_transfer { Some(StatefulTransfer::ReadByte(_)) => {}, Some(StatefulTransfer::ReadWord(data)) => { **byte = (data >> 8) as u8; bus_state.current_transfer = None; } Some(StatefulTransfer::ReadBlock(_)) => { if let Some(data) = self.handle_read_block_data(first_byte, 1) { **byte = data; } else { return Err(SMBusProtocolError::InvalidReadBound(1)); } } _ => return Err(SMBusProtocolError::InvalidReadBound(2)), } } n => { if let Some(StatefulTransfer::ReadBlock(_)) = bus_state.current_transfer { if let Some(data) = self.handle_read_block_data(bus_state.received_data[0], n - 1) { **byte = data; } } } } bus_state.index += 1; } I2CEvent::Stopped => { if bus_state.direction == Some(Direction::MasterToSlave) { match bus_state.index { 0 => return Err(SMBusProtocolError::QuickCommandUnsupported), 1 => { if let Err(()) = self.handle_write_byte(bus_state.received_data[0]) { return Err(SMBusProtocolError::WriteByteUnsupported); } } 2 => { if let Err(()) = self.handle_write_byte_data( bus_state.received_data[0], bus_state.received_data[1], ) { return Err(SMBusProtocolError::InvalidWriteRegister( bus_state.received_data[0], )); } } 3 => { let data: u16 = bus_state.received_data[1] as u16 | (bus_state.received_data[2] as u16) << 8; if let Err(()) = self.handle_write_word_data(bus_state.received_data[0], data) { return Err(SMBusProtocolError::InvalidWriteRegister( bus_state.received_data[0], )); }; } 4..=RECEIVE_BUFFER_SIZE => { let reg = bus_state.received_data[0]; let count = bus_state.received_data[1]; if count > 32 { return Err(SMBusProtocolError::InvalidWriteBlockSize(count)); } let slice = &bus_state.received_data[2usize..count as usize + 2]; if let Err(()) = self.handle_write_block_data(reg, count, slice) { return Err(SMBusProtocolError::InvalidWriteBound(count)); } } n => return Err(SMBusProtocolError::InvalidWriteBound(n)) }; } bus_state.received_data.iter_mut().for_each(|x| *x = 0); bus_state.index = 0; bus_state.direction = None; } } return Ok(()); } } #[derive(Debug, Copy, Clone, Eq, PartialEq)] pub enum Direction { MasterToSlave, SlaveToMaster, } #[derive(Debug)] pub enum I2CEvent<'a> { Initiated { direction: Direction }, ReceivedByte { byte: u8 }, RequestedByte { byte: &'a mut u8 }, Stopped, } #[derive(Debug, PartialEq, Eq)] enum StatefulTransfer { ReadByte(u8), ReadWord(u16), ReadBlock(u8), } const RECEIVE_BUFFER_SIZE: u8 = 34; #[derive(Debug)] pub struct SMBusState { index: u8, received_data: [u8; RECEIVE_BUFFER_SIZE as usize], direction: Option<Direction>, current_transfer: Option<StatefulTransfer>, } impl Default for SMBusState { fn default() -> Self { Self { index: 0, received_data: [0; RECEIVE_BUFFER_SIZE as usize], direction: None, current_transfer: None, } } } #[derive(Debug, Eq, PartialEq, Clone, Copy)] pub enum SMBusProtocolError { WrongDirection(Option<Direction>), QuickCommandUnsupported, UnsupportedBlockLength(u8), ReadByteUnsupported, WriteByteUnsupported, InvalidWriteBound(u8), InvalidReadBound(u8), InvalidWriteBlockSize(u8), InvalidReadBlockSize(u8), InvalidReadRegister(u8), InvalidWriteRegister(u8), }