Struct kernel::services::i2c::messages::Transfer

pub struct Transfer {
    pub buf: FixedVec<u8>,
    pub len: usize,
    pub end: bool,
    pub dir: OpKind,
    pub rsp: Sender<Result<FixedVec<u8>, ErrorKind>>,
}

An I²C bus transfer within a Transaction.

This message is sent to the I2cService by a Transaction in order to perform an individual bus read or write as part of that transaction.

Fields

buf: FixedVec<u8>

A buffer to read bytes into (if dir is OpKind::Read), or write bytes from (if dir is OpKind::Write).

If performing a write, this buffer is guaranteed to contain at least len bytes. The driver is expected to write the contents of this buffer to the I²C bus starting at buf[0] and ending at buf[len - 1].

If performing a read, this buffer is guaranteed to have at least len capacity remaining. The driver is expected to read by appending bytes to the end of this buffer until len bytes have been appended.

len: usize

The number of bytes to read or write from buf in this I²C bus transfer.

end: bool

If true, this transfer is the last transfer in the transaction.

If end is true, the driver is expected to send a STOP condition when the transfer has completed. Otherwise, the driver should send a repeated START, as additional transfers will be performed.

Once the driver has completed a transfer with end == true, it is permitted to return errors for any subsequent transfers in the current transaction.

dir: OpKind

Whether this is a read (OpKind::Read) or write (OpKind::Write) transfer.

rsp: Sender<Result<FixedVec<u8>, ErrorKind>>

Sender for responses once the transfer has completed.

Once the driver has completed the transfer, it is required to send back the buf received in this Transfer message if the transfer completed successfully.

If the transfer was a read, then buf should contain the bytes read from the I²C bus. If the transfer was a write, buf may contain any data, or be empty.

If the transfer could not be completed successfully, then the driver must send an i2c::ErrorKind indicating the cause of the failure, instead.