embassy/embassy-nrf/src/buffered_uarte.rs

463 lines
16 KiB
Rust
Raw Normal View History

2021-11-30 22:29:45 +00:00
//! Async buffered UART
//!
//! WARNING!!! The functionality provided here is intended to be used only
//! in situations where hardware flow control are available i.e. CTS and RTS.
//! This is a problem that should be addressed at a later stage and can be
//! fully explained at <https://github.com/embassy-rs/embassy/issues/536>.
//!
//! Note that discarding a future from a read or write operation may lead to losing
//! data. For example, when using `futures_util::future::select` and completion occurs
//! on the "other" future, you should capture the incomplete future and continue to use
//! it for the next read or write. This pattern is a consideration for all IO, and not
//! just serial communications.
//!
//! Please also see [crate::uarte] to understand when [BufferedUarte] should be used.
2021-11-30 22:29:45 +00:00
2020-09-22 16:03:43 +00:00
use core::cmp::min;
2022-05-04 18:48:37 +00:00
use core::future::Future;
2020-09-22 16:03:43 +00:00
use core::sync::atomic::{compiler_fence, Ordering};
2022-05-04 18:48:37 +00:00
use core::task::Poll;
2022-06-12 20:15:44 +00:00
use embassy_cortex_m::peripheral::{PeripheralMutex, PeripheralState, StateStorage};
use embassy_hal_common::ring_buffer::RingBuffer;
use embassy_hal_common::{into_ref, PeripheralRef};
use embassy_util::waitqueue::WakerRegistration;
2022-05-04 18:48:37 +00:00
use futures::future::poll_fn;
2022-06-12 20:15:44 +00:00
// Re-export SVD variants to allow user to directly set values
pub use pac::uarte0::{baudrate::BAUDRATE_A as Baudrate, config::PARITY_A as Parity};
2020-09-22 16:03:43 +00:00
2022-02-12 00:04:01 +00:00
use crate::gpio::Pin as GpioPin;
2022-06-12 20:15:44 +00:00
use crate::interrupt::InterruptExt;
use crate::ppi::{AnyConfigurableChannel, ConfigurableChannel, Event, Ppi, Task};
2022-06-12 20:15:44 +00:00
use crate::timer::{Frequency, Instance as TimerInstance, Timer};
use crate::uarte::{apply_workaround_for_enable_anomaly, Config, Instance as UarteInstance};
use crate::{pac, Peripheral};
2020-09-22 16:03:43 +00:00
#[derive(Copy, Clone, Debug, PartialEq)]
enum RxState {
Idle,
Receiving,
}
2021-01-05 20:14:04 +00:00
2020-09-22 16:03:43 +00:00
#[derive(Copy, Clone, Debug, PartialEq)]
enum TxState {
Idle,
Transmitting(usize),
}
pub struct State<'d, U: UarteInstance, T: TimerInstance>(StateStorage<StateInner<'d, U, T>>);
impl<'d, U: UarteInstance, T: TimerInstance> State<'d, U, T> {
pub fn new() -> Self {
Self(StateStorage::new())
}
}
struct StateInner<'d, U: UarteInstance, T: TimerInstance> {
_peri: PeripheralRef<'d, U>,
timer: Timer<'d, T>,
_ppi_ch1: Ppi<'d, AnyConfigurableChannel, 1, 2>,
_ppi_ch2: Ppi<'d, AnyConfigurableChannel, 1, 1>,
2021-01-05 20:14:04 +00:00
rx: RingBuffer<'d>,
2021-01-05 20:14:04 +00:00
rx_state: RxState,
rx_waker: WakerRegistration,
tx: RingBuffer<'d>,
2021-01-05 20:14:04 +00:00
tx_state: TxState,
tx_waker: WakerRegistration,
}
2020-09-22 16:03:43 +00:00
/// Interface to a UARTE instance
pub struct BufferedUarte<'d, U: UarteInstance, T: TimerInstance> {
inner: PeripheralMutex<'d, StateInner<'d, U, T>>,
2020-09-22 16:03:43 +00:00
}
impl<'d, U: UarteInstance, T: TimerInstance> Unpin for BufferedUarte<'d, U, T> {}
impl<'d, U: UarteInstance, T: TimerInstance> BufferedUarte<'d, U, T> {
pub fn new(
state: &'d mut State<'d, U, T>,
peri: impl Peripheral<P = U> + 'd,
timer: impl Peripheral<P = T> + 'd,
ppi_ch1: impl Peripheral<P = impl ConfigurableChannel + 'd> + 'd,
ppi_ch2: impl Peripheral<P = impl ConfigurableChannel + 'd> + 'd,
irq: impl Peripheral<P = U::Interrupt> + 'd,
rxd: impl Peripheral<P = impl GpioPin> + 'd,
txd: impl Peripheral<P = impl GpioPin> + 'd,
cts: impl Peripheral<P = impl GpioPin> + 'd,
rts: impl Peripheral<P = impl GpioPin> + 'd,
config: Config,
rx_buffer: &'d mut [u8],
tx_buffer: &'d mut [u8],
) -> Self {
into_ref!(peri, ppi_ch1, ppi_ch2, irq, rxd, txd, cts, rts);
2020-09-22 16:03:43 +00:00
2021-04-14 14:01:43 +00:00
let r = U::regs();
2021-06-26 07:58:36 +00:00
let mut timer = Timer::new(timer);
2020-09-22 16:03:43 +00:00
rxd.conf().write(|w| w.input().connect().drive().h0h1());
r.psel.rxd.write(|w| unsafe { w.bits(rxd.psel_bits()) });
2020-09-22 16:03:43 +00:00
txd.set_high();
txd.conf().write(|w| w.dir().output().drive().h0h1());
r.psel.txd.write(|w| unsafe { w.bits(txd.psel_bits()) });
2020-09-22 16:03:43 +00:00
2022-02-12 00:04:01 +00:00
cts.conf().write(|w| w.input().connect().drive().h0h1());
r.psel.cts.write(|w| unsafe { w.bits(cts.psel_bits()) });
2022-02-12 00:04:01 +00:00
rts.set_high();
rts.conf().write(|w| w.dir().output().drive().h0h1());
r.psel.rts.write(|w| unsafe { w.bits(rts.psel_bits()) });
r.baudrate.write(|w| w.baudrate().variant(config.baudrate));
r.config.write(|w| w.parity().variant(config.parity));
2020-09-22 16:03:43 +00:00
// Configure
r.config.write(|w| {
2022-02-12 00:04:01 +00:00
w.hwfc().bit(true);
w.parity().variant(config.parity);
w
});
r.baudrate.write(|w| w.baudrate().variant(config.baudrate));
2020-09-22 16:03:43 +00:00
// Enable interrupts
r.intenset.write(|w| w.endrx().set().endtx().set());
2020-09-22 16:03:43 +00:00
// Disable the irq, let the Registration enable it when everything is set up.
irq.disable();
irq.pend();
// Enable UARTE instance
apply_workaround_for_enable_anomaly(&r);
r.enable.write(|w| w.enable().enabled());
// BAUDRATE register values are `baudrate * 2^32 / 16000000`
// source: https://devzone.nordicsemi.com/f/nordic-q-a/391/uart-baudrate-register-values
//
// We want to stop RX if line is idle for 2 bytes worth of time
// That is 20 bits (each byte is 1 start bit + 8 data bits + 1 stop bit)
// This gives us the amount of 16M ticks for 20 bits.
let timeout = 0x8000_0000 / (config.baudrate as u32 / 40);
2021-06-26 07:58:36 +00:00
timer.set_frequency(Frequency::F16MHz);
timer.cc(0).write(timeout);
timer.cc(0).short_compare_clear();
timer.cc(0).short_compare_stop();
let mut ppi_ch1 = Ppi::new_one_to_two(
2022-07-23 12:27:45 +00:00
ppi_ch1.map_into(),
Event::from_reg(&r.events_rxdrdy),
timer.task_clear(),
timer.task_start(),
);
ppi_ch1.enable();
let mut ppi_ch2 = Ppi::new_one_to_one(
2022-07-23 12:27:45 +00:00
ppi_ch2.map_into(),
timer.cc(0).event_compare(),
Task::from_reg(&r.tasks_stoprx),
);
ppi_ch2.enable();
Self {
2022-07-23 12:27:45 +00:00
inner: PeripheralMutex::new(irq, &mut state.0, move || StateInner {
_peri: peri,
timer,
_ppi_ch1: ppi_ch1,
_ppi_ch2: ppi_ch2,
rx: RingBuffer::new(rx_buffer),
rx_state: RxState::Idle,
rx_waker: WakerRegistration::new(),
tx: RingBuffer::new(tx_buffer),
tx_state: TxState::Idle,
tx_waker: WakerRegistration::new(),
}),
}
2020-09-22 16:03:43 +00:00
}
2021-01-05 20:14:04 +00:00
pub fn set_baudrate(&mut self, baudrate: Baudrate) {
self.inner.with(|state| {
2021-04-14 14:01:43 +00:00
let r = U::regs();
2021-01-11 09:40:37 +00:00
let timeout = 0x8000_0000 / (baudrate as u32 / 40);
state.timer.cc(0).write(timeout);
2021-06-26 07:58:36 +00:00
state.timer.clear();
2021-01-11 09:40:37 +00:00
r.baudrate.write(|w| w.baudrate().variant(baudrate));
2021-01-11 09:40:37 +00:00
});
}
2020-09-22 16:03:43 +00:00
}
2022-05-04 18:48:37 +00:00
impl<'d, U: UarteInstance, T: TimerInstance> embedded_io::Io for BufferedUarte<'d, U, T> {
type Error = core::convert::Infallible;
}
impl<'d, U: UarteInstance, T: TimerInstance> embedded_io::asynch::Read for BufferedUarte<'d, U, T> {
type ReadFuture<'a> = impl Future<Output = Result<usize, Self::Error>>
where
Self: 'a;
fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> Self::ReadFuture<'a> {
poll_fn(move |cx| {
let mut do_pend = false;
let res = self.inner.with(|state| {
compiler_fence(Ordering::SeqCst);
trace!("poll_read");
// We have data ready in buffer? Return it.
let data = state.rx.pop_buf();
if !data.is_empty() {
trace!(" got {:?} {:?}", data.as_ptr() as u32, data.len());
let len = data.len().min(buf.len());
2022-05-04 18:48:37 +00:00
buf[..len].copy_from_slice(&data[..len]);
state.rx.pop(len);
do_pend = true;
return Poll::Ready(Ok(len));
}
trace!(" empty");
state.rx_waker.register(cx.waker());
Poll::Pending
});
if do_pend {
self.inner.pend();
2021-01-05 20:14:04 +00:00
}
2022-05-04 18:48:37 +00:00
res
})
2020-09-22 16:03:43 +00:00
}
}
2022-06-12 20:15:44 +00:00
impl<'d, U: UarteInstance, T: TimerInstance> embedded_io::asynch::BufRead for BufferedUarte<'d, U, T> {
type FillBufFuture<'a> = impl Future<Output = Result<&'a [u8], Self::Error>>
where
Self: 'a;
fn fill_buf<'a>(&'a mut self) -> Self::FillBufFuture<'a> {
poll_fn(move |cx| {
self.inner.with(|state| {
compiler_fence(Ordering::SeqCst);
trace!("fill_buf");
// We have data ready in buffer? Return it.
let buf = state.rx.pop_buf();
if !buf.is_empty() {
trace!(" got {:?} {:?}", buf.as_ptr() as u32, buf.len());
let buf: &[u8] = buf;
// Safety: buffer lives as long as uart
let buf: &[u8] = unsafe { core::mem::transmute(buf) };
return Poll::Ready(Ok(buf));
}
trace!(" empty");
state.rx_waker.register(cx.waker());
Poll::<Result<&[u8], Self::Error>>::Pending
})
})
}
fn consume(&mut self, amt: usize) {
let signal = self.inner.with(|state| {
let full = state.rx.is_full();
state.rx.pop(amt);
full
});
if signal {
self.inner.pend();
}
}
}
2022-06-12 20:15:44 +00:00
impl<'d, U: UarteInstance, T: TimerInstance> embedded_io::asynch::Write for BufferedUarte<'d, U, T> {
2022-05-04 18:48:37 +00:00
type WriteFuture<'a> = impl Future<Output = Result<usize, Self::Error>>
where
Self: 'a;
2020-09-22 16:03:43 +00:00
2022-05-04 18:48:37 +00:00
fn write<'a>(&'a mut self, buf: &'a [u8]) -> Self::WriteFuture<'a> {
poll_fn(move |cx| {
let res = self.inner.with(|state| {
trace!("poll_write: {:?}", buf.len());
2020-09-22 16:03:43 +00:00
2022-05-04 18:48:37 +00:00
let tx_buf = state.tx.push_buf();
if tx_buf.is_empty() {
trace!("poll_write: pending");
state.tx_waker.register(cx.waker());
return Poll::Pending;
}
2020-09-22 16:03:43 +00:00
2022-05-04 18:48:37 +00:00
let n = min(tx_buf.len(), buf.len());
tx_buf[..n].copy_from_slice(&buf[..n]);
state.tx.push(n);
2020-09-22 16:03:43 +00:00
2022-05-04 18:48:37 +00:00
trace!("poll_write: queued {:?}", n);
compiler_fence(Ordering::SeqCst);
2022-05-04 18:48:37 +00:00
Poll::Ready(Ok(n))
});
2022-05-04 18:48:37 +00:00
self.inner.pend();
res
})
2020-09-22 16:03:43 +00:00
}
2022-05-04 18:48:37 +00:00
type FlushFuture<'a> = impl Future<Output = Result<(), Self::Error>>
where
Self: 'a;
2022-05-04 18:48:37 +00:00
fn flush<'a>(&'a mut self) -> Self::FlushFuture<'a> {
poll_fn(move |cx| {
self.inner.with(|state| {
trace!("poll_flush");
if !state.tx.is_empty() {
trace!("poll_flush: pending");
state.tx_waker.register(cx.waker());
return Poll::Pending;
}
2022-05-04 18:48:37 +00:00
Poll::Ready(Ok(()))
})
})
}
}
impl<'a, U: UarteInstance, T: TimerInstance> Drop for StateInner<'a, U, T> {
fn drop(&mut self) {
2021-04-14 14:01:43 +00:00
let r = U::regs();
// TODO this probably deadlocks. do like Uarte instead.
2021-06-26 07:58:36 +00:00
self.timer.stop();
if let RxState::Receiving = self.rx_state {
r.tasks_stoprx.write(|w| unsafe { w.bits(1) });
}
if let TxState::Transmitting(_) = self.tx_state {
r.tasks_stoptx.write(|w| unsafe { w.bits(1) });
}
if let RxState::Receiving = self.rx_state {
low_power_wait_until(|| r.events_endrx.read().bits() == 1);
}
if let TxState::Transmitting(_) = self.tx_state {
low_power_wait_until(|| r.events_endtx.read().bits() == 1);
}
}
}
impl<'a, U: UarteInstance, T: TimerInstance> PeripheralState for StateInner<'a, U, T> {
2021-01-06 21:48:54 +00:00
type Interrupt = U::Interrupt;
2020-09-22 16:03:43 +00:00
fn on_interrupt(&mut self) {
trace!("irq: start");
2021-04-14 14:01:43 +00:00
let r = U::regs();
loop {
2020-09-22 16:03:43 +00:00
match self.rx_state {
RxState::Idle => {
trace!(" irq_rx: in state idle");
let buf = self.rx.push_buf();
2021-02-14 00:41:36 +00:00
if !buf.is_empty() {
2020-09-22 16:03:43 +00:00
trace!(" irq_rx: starting {:?}", buf.len());
self.rx_state = RxState::Receiving;
// Set up the DMA read
r.rxd.ptr.write(|w|
2020-09-22 16:03:43 +00:00
// The PTR field is a full 32 bits wide and accepts the full range
// of values.
unsafe { w.ptr().bits(buf.as_ptr() as u32) });
r.rxd.maxcnt.write(|w|
2020-09-22 16:03:43 +00:00
// We're giving it the length of the buffer, so no danger of
// accessing invalid memory. We have verified that the length of the
// buffer fits in an `u8`, so the cast to `u8` is also fine.
//
// The MAXCNT field is at least 8 bits wide and accepts the full
// range of values.
unsafe { w.maxcnt().bits(buf.len() as _) });
trace!(" irq_rx: buf {:?} {:?}", buf.as_ptr() as u32, buf.len());
// Start UARTE Receive transaction
r.tasks_startrx.write(|w| unsafe { w.bits(1) });
2020-09-22 16:03:43 +00:00
}
break;
2020-09-22 16:03:43 +00:00
}
RxState::Receiving => {
trace!(" irq_rx: in state receiving");
if r.events_endrx.read().bits() != 0 {
2021-06-26 07:58:36 +00:00
self.timer.stop();
2020-09-22 16:03:43 +00:00
let n: usize = r.rxd.amount.read().amount().bits() as usize;
2020-09-22 16:03:43 +00:00
trace!(" irq_rx: endrx {:?}", n);
self.rx.push(n);
r.events_endrx.reset();
2020-09-22 16:03:43 +00:00
self.rx_waker.wake();
self.rx_state = RxState::Idle;
} else {
break;
2020-09-22 16:03:43 +00:00
}
}
}
}
loop {
2020-09-22 16:03:43 +00:00
match self.tx_state {
TxState::Idle => {
trace!(" irq_tx: in state Idle");
let buf = self.tx.pop_buf();
2021-02-14 00:41:36 +00:00
if !buf.is_empty() {
2020-09-22 16:03:43 +00:00
trace!(" irq_tx: starting {:?}", buf.len());
self.tx_state = TxState::Transmitting(buf.len());
// Set up the DMA write
r.txd.ptr.write(|w|
2020-09-22 16:03:43 +00:00
// The PTR field is a full 32 bits wide and accepts the full range
// of values.
unsafe { w.ptr().bits(buf.as_ptr() as u32) });
r.txd.maxcnt.write(|w|
2020-09-22 16:03:43 +00:00
// We're giving it the length of the buffer, so no danger of
// accessing invalid memory. We have verified that the length of the
// buffer fits in an `u8`, so the cast to `u8` is also fine.
//
// The MAXCNT field is 8 bits wide and accepts the full range of
// values.
unsafe { w.maxcnt().bits(buf.len() as _) });
// Start UARTE Transmit transaction
r.tasks_starttx.write(|w| unsafe { w.bits(1) });
2020-09-22 16:03:43 +00:00
}
break;
2020-09-22 16:03:43 +00:00
}
TxState::Transmitting(n) => {
trace!(" irq_tx: in state Transmitting");
if r.events_endtx.read().bits() != 0 {
r.events_endtx.reset();
2020-09-22 16:03:43 +00:00
trace!(" irq_tx: endtx {:?}", n);
self.tx.pop(n);
self.tx_waker.wake();
self.tx_state = TxState::Idle;
} else {
break;
2020-09-22 16:03:43 +00:00
}
}
}
}
trace!("irq: end");
}
}
/// Low power blocking wait loop using WFE/SEV.
fn low_power_wait_until(mut condition: impl FnMut() -> bool) {
while !condition() {
// WFE might "eat" an event that would have otherwise woken the executor.
cortex_m::asm::wfe();
}
// Retrigger an event to be transparent to the executor.
cortex_m::asm::sev();
}