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nrf/twim: allow zero length transfers.

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This commit is contained in:
Dario Nieuwenhuis 2022-06-07 14:52:45 +02:00
parent c212f30be0
commit 2be36122c7
1 changed files with 14 additions and 10 deletions
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24
embassy-nrf/src/twim.rs
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@ -60,8 +60,6 @@ impl Default for Config {
pub enum Error {
TxBufferTooLong,
RxBufferTooLong,
TxBufferZeroLength,
RxBufferZeroLength,
Transmit,
Receive,
DMABufferNotInDataMemory,
@ -159,9 +157,6 @@ impl<'d, T: Instance> Twim<'d, T> {
unsafe fn set_tx_buffer(&mut self, buffer: &[u8]) -> Result<(), Error> {
slice_in_ram_or(buffer, Error::DMABufferNotInDataMemory)?;
if buffer.len() == 0 {
return Err(Error::TxBufferZeroLength);
}
if buffer.len() > EASY_DMA_SIZE {
return Err(Error::TxBufferTooLong);
}
@ -193,9 +188,6 @@ impl<'d, T: Instance> Twim<'d, T> {
// NOTE: RAM slice check is not necessary, as a mutable
// slice can only be built from data located in RAM.
if buffer.len() == 0 {
return Err(Error::RxBufferZeroLength);
}
if buffer.len() > EASY_DMA_SIZE {
return Err(Error::RxBufferTooLong);
}
@ -357,6 +349,10 @@ impl<'d, T: Instance> Twim<'d, T> {
// Start write operation.
r.shorts.write(|w| w.lasttx_stop().enabled());
r.tasks_starttx.write(|w| unsafe { w.bits(1) });
if buffer.len() == 0 {
// With a zero-length buffer, LASTTX doesn't fire (because there's no last byte!), so do the STOP ourselves.
r.tasks_stop.write(|w| unsafe { w.bits(1) });
}
Ok(())
}
@ -384,6 +380,10 @@ impl<'d, T: Instance> Twim<'d, T> {
// Start read operation.
r.shorts.write(|w| w.lastrx_stop().enabled());
r.tasks_startrx.write(|w| unsafe { w.bits(1) });
if buffer.len() == 0 {
// With a zero-length buffer, LASTRX doesn't fire (because there's no last byte!), so do the STOP ourselves.
r.tasks_stop.write(|w| unsafe { w.bits(1) });
}
Ok(())
}
@ -424,6 +424,12 @@ impl<'d, T: Instance> Twim<'d, T> {
w
});
r.tasks_starttx.write(|w| unsafe { w.bits(1) });
if wr_buffer.len() == 0 && rd_buffer.len() == 0 {
// With a zero-length buffer, LASTRX/LASTTX doesn't fire (because there's no last byte!), so do the STOP ourselves.
// TODO handle when only one of the buffers is zero length
r.tasks_stop.write(|w| unsafe { w.bits(1) });
}
Ok(())
}
@ -800,8 +806,6 @@ mod eh1 {
match *self {
Self::TxBufferTooLong => embedded_hal_1::i2c::ErrorKind::Other,
Self::RxBufferTooLong => embedded_hal_1::i2c::ErrorKind::Other,
Self::TxBufferZeroLength => embedded_hal_1::i2c::ErrorKind::Other,
Self::RxBufferZeroLength => embedded_hal_1::i2c::ErrorKind::Other,
Self::Transmit => embedded_hal_1::i2c::ErrorKind::Other,
Self::Receive => embedded_hal_1::i2c::ErrorKind::Other,
Self::DMABufferNotInDataMemory => embedded_hal_1::i2c::ErrorKind::Other,