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stm32/spi: fix blocking_write on nosck spi.

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Fixes #2902.
This commit is contained in:
Dario Nieuwenhuis 2024-06-03 00:57:53 +02:00
parent 7b590334e6
commit 348c87fc2f
3 changed files with 72 additions and 35 deletions
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66
embassy-stm32/src/spi/mod.rs
View File

@ -351,17 +351,46 @@ impl<'d, M: PeriMode> Spi<'d, M> {
/// Blocking write.
pub fn blocking_write<W: Word>(&mut self, words: &[W]) -> Result<(), Error> {
// needed in v3+ to avoid overrun causing the SPI RX state machine to get stuck...?
#[cfg(any(spi_v3, spi_v4, spi_v5))]
self.info.regs.cr1().modify(|w| w.set_spe(false));
self.info.regs.cr1().modify(|w| w.set_spe(true));
flush_rx_fifo(self.info.regs);
self.set_word_size(W::CONFIG);
for word in words.iter() {
let _ = transfer_word(self.info.regs, *word)?;
// this cannot use `transfer_word` because on SPIv2 and higher,
// the SPI RX state machine hangs if no physical pin is connected to the SCK AF.
// This is the case when the SPI has been created with `new_(blocking_?)txonly_nosck`.
// See https://github.com/embassy-rs/embassy/issues/2902
// This is not documented as an errata by ST, and I've been unable to find anything online...
#[cfg(not(any(spi_v1, spi_f1)))]
write_word(self.info.regs, *word)?;
// if we're doing tx only, after writing the last byte to FIFO we have to wait
// until it's actually sent. On SPIv1 you're supposed to use the BSY flag for this
// but apparently it's broken, it clears too soon. Workaround is to wait for RXNE:
// when it gets set you know the transfer is done, even if you don't care about rx.
// Luckily this doesn't affect SPIv2+.
// See http://efton.sk/STM32/gotcha/g68.html
// ST doesn't seem to document this in errata sheets (?)
#[cfg(any(spi_v1, spi_f1))]
transfer_word(self.info.regs, *word)?;
}
// wait until last word is transmitted. (except on v1, see above)
#[cfg(not(any(spi_v1, spi_f1, spi_v2)))]
while !self.info.regs.sr().read().txc() {}
#[cfg(spi_v2)]
while self.info.regs.sr().read().bsy() {}
Ok(())
}
/// Blocking read.
pub fn blocking_read<W: Word>(&mut self, words: &mut [W]) -> Result<(), Error> {
// needed in v3+ to avoid overrun causing the SPI RX state machine to get stuck...?
#[cfg(any(spi_v3, spi_v4, spi_v5))]
self.info.regs.cr1().modify(|w| w.set_spe(false));
self.info.regs.cr1().modify(|w| w.set_spe(true));
flush_rx_fifo(self.info.regs);
self.set_word_size(W::CONFIG);
@ -375,6 +404,9 @@ impl<'d, M: PeriMode> Spi<'d, M> {
///
/// This writes the contents of `data` on MOSI, and puts the received data on MISO in `data`, at the same time.
pub fn blocking_transfer_in_place<W: Word>(&mut self, words: &mut [W]) -> Result<(), Error> {
// needed in v3+ to avoid overrun causing the SPI RX state machine to get stuck...?
#[cfg(any(spi_v3, spi_v4, spi_v5))]
self.info.regs.cr1().modify(|w| w.set_spe(false));
self.info.regs.cr1().modify(|w| w.set_spe(true));
flush_rx_fifo(self.info.regs);
self.set_word_size(W::CONFIG);
@ -391,6 +423,9 @@ impl<'d, M: PeriMode> Spi<'d, M> {
/// The transfer runs for `max(read.len(), write.len())` bytes. If `read` is shorter extra bytes are ignored.
/// If `write` is shorter it is padded with zero bytes.
pub fn blocking_transfer<W: Word>(&mut self, read: &mut [W], write: &[W]) -> Result<(), Error> {
// needed in v3+ to avoid overrun causing the SPI RX state machine to get stuck...?
#[cfg(any(spi_v3, spi_v4, spi_v5))]
self.info.regs.cr1().modify(|w| w.set_spe(false));
self.info.regs.cr1().modify(|w| w.set_spe(true));
flush_rx_fifo(self.info.regs);
self.set_word_size(W::CONFIG);
@ -465,7 +500,6 @@ impl<'d> Spi<'d, Blocking> {
/// Create a new SPI driver, in TX-only mode, without SCK pin.
///
/// This can be useful for bit-banging non-SPI protocols.
#[cfg(any(spi_v1, spi_f1))] // no SCK pin causes it to hang on spiv2+ for unknown reasons.
pub fn new_blocking_txonly_nosck<T: Instance>(
peri: impl Peripheral<P = T> + 'd,
mosi: impl Peripheral<P = impl MosiPin<T>> + 'd,
@ -550,7 +584,6 @@ impl<'d> Spi<'d, Async> {
/// Create a new SPI driver, in TX-only mode, without SCK pin.
///
/// This can be useful for bit-banging non-SPI protocols.
#[cfg(any(spi_v1, spi_f1))] // no SCK pin causes it to hang on spiv2+ for unknown reasons.
pub fn new_txonly_nosck<T: Instance>(
peri: impl Peripheral<P = T> + 'd,
mosi: impl Peripheral<P = impl MosiPin<T>> + 'd,
@ -900,8 +933,8 @@ impl RegsExt for Regs {
}
}
fn check_error_flags(sr: regs::Sr) -> Result<(), Error> {
if sr.ovr() {
fn check_error_flags(sr: regs::Sr, ovr: bool) -> Result<(), Error> {
if sr.ovr() && ovr {
return Err(Error::Overrun);
}
#[cfg(not(any(spi_f1, spi_v3, spi_v4, spi_v5)))]
@ -927,11 +960,11 @@ fn check_error_flags(sr: regs::Sr) -> Result<(), Error> {
Ok(())
}
fn spin_until_tx_ready(regs: Regs) -> Result<(), Error> {
fn spin_until_tx_ready(regs: Regs, ovr: bool) -> Result<(), Error> {
loop {
let sr = regs.sr().read();
check_error_flags(sr)?;
check_error_flags(sr, ovr)?;
#[cfg(not(any(spi_v3, spi_v4, spi_v5)))]
if sr.txe() {
@ -948,7 +981,7 @@ fn spin_until_rx_ready(regs: Regs) -> Result<(), Error> {
loop {
let sr = regs.sr().read();
check_error_flags(sr)?;
check_error_flags(sr, true)?;
#[cfg(not(any(spi_v3, spi_v4, spi_v5)))]
if sr.rxne() {
@ -1032,7 +1065,7 @@ fn finish_dma(regs: Regs) {
}
fn transfer_word<W: Word>(regs: Regs, tx_word: W) -> Result<W, Error> {
spin_until_tx_ready(regs)?;
spin_until_tx_ready(regs, true)?;
unsafe {
ptr::write_volatile(regs.tx_ptr(), tx_word);
@ -1047,6 +1080,21 @@ fn transfer_word<W: Word>(regs: Regs, tx_word: W) -> Result<W, Error> {
Ok(rx_word)
}
#[allow(unused)] // unused in SPIv1
fn write_word<W: Word>(regs: Regs, tx_word: W) -> Result<(), Error> {
// for write, we intentionally ignore the rx fifo, which will cause
// overrun errors that we have to ignore.
spin_until_tx_ready(regs, false)?;
unsafe {
ptr::write_volatile(regs.tx_ptr(), tx_word);
#[cfg(any(spi_v3, spi_v4, spi_v5))]
regs.cr1().modify(|reg| reg.set_cstart(true));
}
Ok(())
}
// Note: It is not possible to impl these traits generically in embedded-hal 0.2 due to a conflict with
// some marker traits. For details, see https://github.com/rust-embedded/embedded-hal/pull/289
macro_rules! impl_blocking {

10
tests/stm32/src/bin/spi.rs
View File

@ -94,19 +94,11 @@ async fn main(_spawner: Spawner) {
drop(spi);
// Test tx-only nosck.
#[cfg(feature = "spi-v1")]
{
let mut spi = Spi::new_blocking_txonly_nosck(&mut spi_peri, &mut mosi, spi_config);
spi.blocking_transfer(&mut buf, &data).unwrap();
spi.blocking_transfer_in_place(&mut buf).unwrap();
spi.blocking_write(&buf).unwrap();
spi.blocking_read(&mut buf).unwrap();
spi.blocking_transfer::<u8>(&mut [], &[]).unwrap();
spi.blocking_transfer_in_place::<u8>(&mut []).unwrap();
spi.blocking_read::<u8>(&mut []).unwrap();
spi.blocking_write::<u8>(&[]).unwrap();
spi.blocking_write(&buf).unwrap();
drop(spi);
}
info!("Test OK");
cortex_m::asm::bkpt();

3
tests/stm32/src/bin/spi_dma.rs
View File

@ -132,8 +132,6 @@ async fn main(_spawner: Spawner) {
drop(spi);
// Test tx-only nosck.
#[cfg(feature = "spi-v1")]
{
let mut spi = Spi::new_txonly_nosck(&mut spi_peri, &mut mosi, &mut tx_dma, spi_config);
spi.blocking_write(&buf).unwrap();
spi.write(&buf).await.unwrap();
@ -144,7 +142,6 @@ async fn main(_spawner: Spawner) {
spi.write::<u8>(&[]).await.unwrap();
spi.blocking_write::<u8>(&[]).unwrap();
drop(spi);
}
info!("Test OK");
cortex_m::asm::bkpt();