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Refactor SPI and fix write bug

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* SPI write v2 was hanging in write due to an infinite loop
* SPI word write was not followed by a read back

The u8 and u16 write/read logic have been refactored into write_word and
read_word.
This commit is contained in:
Ulf Lilleengen 2021-05-27 23:05:42 +02:00
parent c4ea7427fa
commit edec5833b3
2 changed files with 59 additions and 106 deletions
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1
embassy-stm32/src/spi/mod.rs
View file

@ -12,6 +12,7 @@ use crate::gpio::Pin;
pub enum Error {
Framing,
Crc,
ModeFault,
Overrun,
}

164
embassy-stm32/src/spi/v2.rs
View file

@ -153,6 +153,54 @@ impl<'d, T: Instance> Drop for Spi<'d, T> {
}
}
trait Word {}
impl Word for u8 {}
impl Word for u16 {}
/// Write a single word blocking. Assumes word size have already been set.
fn write_word<W: Word>(regs: &'static crate::pac::spi::Spi, word: W) -> Result<(), Error> {
loop {
let sr = unsafe { regs.sr().read() };
if sr.ovr() {
return Err(Error::Overrun);
} else if sr.fre() {
return Err(Error::Framing);
} else if sr.modf() {
return Err(Error::ModeFault);
} else if sr.crcerr() {
return Err(Error::Crc);
} else if sr.txe() {
unsafe {
let dr = regs.dr().ptr() as *mut W;
ptr::write_volatile(dr, word);
}
return Ok(());
}
}
}
/// Read a single word blocking. Assumes word size have already been set.
fn read_word<W: Word>(regs: &'static crate::pac::spi::Spi) -> Result<W, Error> {
loop {
let sr = unsafe { regs.sr().read() };
if sr.ovr() {
return Err(Error::Overrun);
} else if sr.modf() {
return Err(Error::ModeFault);
} else if sr.fre() {
return Err(Error::Framing);
} else if sr.crcerr() {
return Err(Error::Crc);
} else if sr.rxne() {
unsafe {
let dr = regs.dr().ptr() as *const W;
return Ok(ptr::read_volatile(dr));
}
}
}
}
impl<'d, T: Instance> embedded_hal::blocking::spi::Write<u8> for Spi<'d, T> {
type Error = Error;
@ -160,29 +208,9 @@ impl<'d, T: Instance> embedded_hal::blocking::spi::Write<u8> for Spi<'d, T> {
Self::set_word_size(WordSize::EightBit);
let regs = T::regs();
for (i, word) in words.iter().enumerate() {
while unsafe { !regs.sr().read().txe() } {
// spin
}
unsafe {
let dr = regs.dr().ptr() as *mut u8;
ptr::write_volatile(dr, *word);
}
loop {
let sr = unsafe { regs.sr().read() };
if sr.fre() {
return Err(Error::Framing);
}
if sr.ovr() {
return Err(Error::Overrun);
}
if sr.crcerr() {
return Err(Error::Crc);
}
if !sr.txe() {
// loop waiting for TXE
}
}
for word in words.iter() {
write_word(regs, *word)?;
let _: u8 = read_word(regs)?;
}
Ok(())
@ -196,43 +224,9 @@ impl<'d, T: Instance> embedded_hal::blocking::spi::Transfer<u8> for Spi<'d, T> {
Self::set_word_size(WordSize::EightBit);
let regs = T::regs();
for (i, word) in words.iter_mut().enumerate() {
while unsafe { !regs.sr().read().txe() } {
// spin
}
unsafe {
let dr = regs.dr().ptr() as *mut u8;
ptr::write_volatile(dr, *word);
}
loop {
let sr = unsafe { regs.sr().read() };
if sr.rxne() {
break;
}
if sr.fre() {
return Err(Error::Framing);
}
if sr.ovr() {
return Err(Error::Overrun);
}
if sr.crcerr() {
return Err(Error::Crc);
}
}
unsafe {
let dr = regs.dr().ptr() as *const u8;
*word = ptr::read_volatile(dr);
}
let sr = unsafe { regs.sr().read() };
if sr.fre() {
return Err(Error::Framing);
}
if sr.ovr() {
return Err(Error::Overrun);
}
if sr.crcerr() {
return Err(Error::Crc);
}
for word in words.iter_mut() {
write_word(regs, *word)?;
*word = read_word(regs)?;
}
Ok(words)
@ -247,28 +241,8 @@ impl<'d, T: Instance> embedded_hal::blocking::spi::Write<u16> for Spi<'d, T> {
let regs = T::regs();
for word in words.iter() {
while unsafe { !regs.sr().read().txe() } {
// spin
}
unsafe {
let dr = regs.dr().ptr() as *mut u16;
ptr::write_volatile(dr, *word);
}
loop {
let sr = unsafe { regs.sr().read() };
if sr.fre() {
return Err(Error::Framing);
}
if sr.ovr() {
return Err(Error::Overrun);
}
if sr.crcerr() {
return Err(Error::Crc);
}
if !sr.txe() {
// loop waiting for TXE
}
}
write_word(regs, *word)?;
let _: u16 = read_word(regs)?;
}
Ok(())
@ -283,30 +257,8 @@ impl<'d, T: Instance> embedded_hal::blocking::spi::Transfer<u16> for Spi<'d, T>
let regs = T::regs();
for word in words.iter_mut() {
while unsafe { !regs.sr().read().txe() } {
// spin
}
unsafe {
let dr = regs.dr().ptr() as *mut u16;
ptr::write_volatile(dr, *word);
}
while unsafe { !regs.sr().read().rxne() } {
// spin waiting for inbound to shift in.
}
unsafe {
let dr = regs.dr().ptr() as *const u16;
*word = ptr::read_volatile(dr);
}
let sr = unsafe { regs.sr().read() };
if sr.fre() {
return Err(Error::Framing);
}
if sr.ovr() {
return Err(Error::Overrun);
}
if sr.crcerr() {
return Err(Error::Crc);
}
write_word(regs, *word)?;
*word = read_word(regs)?;
}
Ok(words)