sw/host/opentitanlib/src/io/i2c.rs

// Copyright lowRISC contributors.
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0

use serde::{Deserialize, Serialize};
use std::rc::Rc;
use structopt::StructOpt;
use thiserror::Error;

use crate::app::TransportWrapper;
use crate::transport::Result;

#[derive(Debug, StructOpt)]
pub struct I2cParams {
    #[structopt(long, help = "I2C instance", default_value = "0")]
    pub bus: String,
}

impl I2cParams {
    pub fn create(&self, transport: &TransportWrapper) -> Result<Rc<dyn Bus>> {
        let i2c = transport.i2c(&self.bus)?;
        Ok(i2c)
    }
}

/// Errors related to the I2C interface and I2C transactions.  These error messages will be
/// printed in the context of a TransportError::I2cError, that is "I2C error: {}".  So
/// including the words "error" or "i2c" in texts below will probably be redundant.
#[derive(Error, Debug, Deserialize, Serialize)]
pub enum I2cError {
    #[error("Invalid data length: {0}")]
    InvalidDataLength(usize),
    #[error("Bus timeout")]
    Timeout,
    #[error("Bus busy")]
    Busy,
}

/// Represents a I2C transfer.
pub enum Transfer<'rd, 'wr> {
    Read(&'rd mut [u8]),
    Write(&'wr [u8]),
}

/// A trait which represents a I2C Bus.
pub trait Bus {
    /// Runs a I2C transaction composed from the slice of [`Transfer`] objects.
    fn run_transaction(&self, addr: u8, transaction: &mut [Transfer]) -> Result<()>;
}