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2025-02-12 21:13:53 +01:00
//! # Async UART reception functionality for the VA108xx family.
//!
//! This module provides the [RxAsync] and [RxAsyncSharedConsumer] struct which both implement the
//! [embedded_io_async::Read] trait.
//! This trait allows for asynchronous reception of data streams. Please note that this module does
//! not specify/declare the interrupt handlers which must be provided for async support to work.
//! However, it provides four interrupt handlers:
//!
//! - [on_interrupt_uart_a]
//! - [on_interrupt_uart_b]
//! - [on_interrupt_uart_a_overwriting]
//! - [on_interrupt_uart_b_overwriting]
//!
//! The first two are used for the [RxAsync] struct, while the latter two are used with the
//! [RxAsyncSharedConsumer] struct. The later two will overwrite old values in the used ring buffer.
//!
//! Error handling is performed in the user interrupt handler by checking the [AsyncUartErrors]
//! structure returned by the interrupt handlers.
//!
//! # Example
//!
//! - [Async UART RX example](https://egit.irs.uni-stuttgart.de/rust/va108xx-rs/src/branch/main/examples/embassy/src/bin/async-uart-rx.rs)
use core::{cell::RefCell, convert::Infallible, future::Future, sync::atomic::Ordering};
use critical_section::Mutex;
use embassy_sync::waitqueue::AtomicWaker;
use embedded_io::ErrorType;
use heapless::spsc::Consumer;
use portable_atomic::AtomicBool;
use va108xx as pac;
use super::{Instance, Rx, RxError, UartErrors};
static UART_RX_WAKERS: [AtomicWaker; 2] = [const { AtomicWaker::new() }; 2];
static RX_READ_ACTIVE: [AtomicBool; 2] = [const { AtomicBool::new(false) }; 2];
static RX_HAS_DATA: [AtomicBool; 2] = [const { AtomicBool::new(false) }; 2];
struct RxFuture {
uart_idx: usize,
}
impl RxFuture {
pub fn new<Uart: Instance>(_rx: &mut Rx<Uart>) -> Self {
RX_READ_ACTIVE[Uart::IDX as usize].store(true, Ordering::Relaxed);
Self {
uart_idx: Uart::IDX as usize,
}
}
}
impl Future for RxFuture {
type Output = Result<(), RxError>;
fn poll(
self: core::pin::Pin<&mut Self>,
cx: &mut core::task::Context<'_>,
) -> core::task::Poll<Self::Output> {
UART_RX_WAKERS[self.uart_idx].register(cx.waker());
if RX_HAS_DATA[self.uart_idx].load(Ordering::Relaxed) {
return core::task::Poll::Ready(Ok(()));
}
core::task::Poll::Pending
}
}
#[derive(Debug, Clone, Copy)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub struct AsyncUartErrors {
/// Queue has overflowed, data might have been lost.
pub queue_overflow: bool,
/// UART errors.
pub uart_errors: UartErrors,
}
fn on_interrupt_handle_rx_errors<Uart: Instance>(uart: &Uart) -> Option<UartErrors> {
let rx_status = uart.rxstatus().read();
if rx_status.rxovr().bit_is_set()
|| rx_status.rxfrm().bit_is_set()
|| rx_status.rxpar().bit_is_set()
{
let mut errors_val = UartErrors::default();
if rx_status.rxovr().bit_is_set() {
errors_val.overflow = true;
}
if rx_status.rxfrm().bit_is_set() {
errors_val.framing = true;
}
if rx_status.rxpar().bit_is_set() {
errors_val.parity = true;
}
return Some(errors_val);
}
None
}
fn on_interrupt_rx_common_post_processing<Uart: Instance>(
uart: &Uart,
rx_enabled: bool,
read_some_data: bool,
irq_end: u32,
) -> Option<UartErrors> {
if read_some_data {
RX_HAS_DATA[Uart::IDX as usize].store(true, Ordering::Relaxed);
if RX_READ_ACTIVE[Uart::IDX as usize].load(Ordering::Relaxed) {
UART_RX_WAKERS[Uart::IDX as usize].wake();
}
}
let mut errors = None;
// Check for RX errors
if rx_enabled {
errors = on_interrupt_handle_rx_errors(uart);
}
// Clear the interrupt status bits
uart.irq_clr().write(|w| unsafe { w.bits(irq_end) });
errors
}
/// Interrupt handler for UART A.
///
/// Should be called in the user interrupt handler to enable
/// asynchronous reception. This variant will overwrite old data in the ring buffer in case
/// the ring buffer is full.
pub fn on_interrupt_uart_a_overwriting<const N: usize>(
prod: &mut heapless::spsc::Producer<u8, N>,
shared_consumer: &Mutex<RefCell<Option<heapless::spsc::Consumer<'static, u8, N>>>>,
) -> Result<(), AsyncUartErrors> {
on_interrupt_rx_async_heapless_queue_overwriting(
unsafe { pac::Uarta::steal() },
prod,
shared_consumer,
)
}
/// Interrupt handler for UART B.
///
/// Should be called in the user interrupt handler to enable
/// asynchronous reception. This variant will overwrite old data in the ring buffer in case
/// the ring buffer is full.
pub fn on_interrupt_uart_b_overwriting<const N: usize>(
prod: &mut heapless::spsc::Producer<u8, N>,
shared_consumer: &Mutex<RefCell<Option<heapless::spsc::Consumer<'static, u8, N>>>>,
) -> Result<(), AsyncUartErrors> {
on_interrupt_rx_async_heapless_queue_overwriting(
unsafe { pac::Uartb::steal() },
prod,
shared_consumer,
)
}
pub fn on_interrupt_rx_async_heapless_queue_overwriting<Uart: Instance, const N: usize>(
uart: Uart,
prod: &mut heapless::spsc::Producer<u8, N>,
shared_consumer: &Mutex<RefCell<Option<heapless::spsc::Consumer<'static, u8, N>>>>,
) -> Result<(), AsyncUartErrors> {
let irq_end = uart.irq_end().read();
let enb_status = uart.enable().read();
let rx_enabled = enb_status.rxenable().bit_is_set();
let mut read_some_data = false;
let mut queue_overflow = false;
// Half-Full interrupt. We have a guaranteed amount of data we can read.
if irq_end.irq_rx().bit_is_set() {
let available_bytes = uart.rxfifoirqtrg().read().bits() as usize;
// If this interrupt bit is set, the trigger level is available at the very least.
// Read everything as fast as possible
for _ in 0..available_bytes {
let byte = uart.data().read().bits();
if !prod.ready() {
queue_overflow = true;
critical_section::with(|cs| {
let mut cons_ref = shared_consumer.borrow(cs).borrow_mut();
cons_ref.as_mut().unwrap().dequeue();
});
}
prod.enqueue(byte as u8).ok();
}
read_some_data = true;
}
// Timeout, empty the FIFO completely.
if irq_end.irq_rx_to().bit_is_set() {
while uart.rxstatus().read().rdavl().bit_is_set() {
// While there is data in the FIFO, write it into the reception buffer
let byte = uart.data().read().bits();
if !prod.ready() {
queue_overflow = true;
critical_section::with(|cs| {
let mut cons_ref = shared_consumer.borrow(cs).borrow_mut();
cons_ref.as_mut().unwrap().dequeue();
});
}
prod.enqueue(byte as u8).ok();
}
read_some_data = true;
}
let uart_errors =
on_interrupt_rx_common_post_processing(&uart, rx_enabled, read_some_data, irq_end.bits());
if uart_errors.is_some() || queue_overflow {
return Err(AsyncUartErrors {
queue_overflow,
uart_errors: uart_errors.unwrap_or_default(),
});
}
Ok(())
}
/// Interrupt handler for UART A.
///
/// Should be called in the user interrupt handler to enable asynchronous reception.
pub fn on_interrupt_uart_a<const N: usize>(
prod: &mut heapless::spsc::Producer<'_, u8, N>,
) -> Result<(), AsyncUartErrors> {
on_interrupt_rx_async_heapless_queue(unsafe { pac::Uarta::steal() }, prod)
}
/// Interrupt handler for UART B.
///
/// Should be called in the user interrupt handler to enable asynchronous reception.
pub fn on_interrupt_uart_b<const N: usize>(
prod: &mut heapless::spsc::Producer<'_, u8, N>,
) -> Result<(), AsyncUartErrors> {
on_interrupt_rx_async_heapless_queue(unsafe { pac::Uartb::steal() }, prod)
}
pub fn on_interrupt_rx_async_heapless_queue<Uart: Instance, const N: usize>(
uart: Uart,
prod: &mut heapless::spsc::Producer<'_, u8, N>,
) -> Result<(), AsyncUartErrors> {
//let uart = unsafe { Uart::steal() };
let irq_end = uart.irq_end().read();
let enb_status = uart.enable().read();
let rx_enabled = enb_status.rxenable().bit_is_set();
let mut read_some_data = false;
let mut queue_overflow = false;
// Half-Full interrupt. We have a guaranteed amount of data we can read.
if irq_end.irq_rx().bit_is_set() {
let available_bytes = uart.rxfifoirqtrg().read().bits() as usize;
// If this interrupt bit is set, the trigger level is available at the very least.
// Read everything as fast as possible
for _ in 0..available_bytes {
let byte = uart.data().read().bits();
if !prod.ready() {
queue_overflow = true;
}
prod.enqueue(byte as u8).ok();
}
read_some_data = true;
}
// Timeout, empty the FIFO completely.
if irq_end.irq_rx_to().bit_is_set() {
while uart.rxstatus().read().rdavl().bit_is_set() {
// While there is data in the FIFO, write it into the reception buffer
let byte = uart.data().read().bits();
if !prod.ready() {
queue_overflow = true;
}
prod.enqueue(byte as u8).ok();
}
read_some_data = true;
}
let uart_errors =
on_interrupt_rx_common_post_processing(&uart, rx_enabled, read_some_data, irq_end.bits());
if uart_errors.is_some() || queue_overflow {
return Err(AsyncUartErrors {
queue_overflow,
uart_errors: uart_errors.unwrap_or_default(),
});
}
Ok(())
}
struct ActiveReadGuard(usize);
impl Drop for ActiveReadGuard {
fn drop(&mut self) {
RX_READ_ACTIVE[self.0].store(false, Ordering::Relaxed);
}
}
/// Core data structure to allow asynchrnous UART reception.
///
/// If the ring buffer becomes full, data will be lost.
pub struct RxAsync<Uart: Instance, const N: usize> {
rx: Rx<Uart>,
pub queue: heapless::spsc::Consumer<'static, u8, N>,
}
impl<Uart: Instance, const N: usize> ErrorType for RxAsync<Uart, N> {
/// Error reporting is done using atomic booleans and the [get_and_clear_errors] function.
type Error = Infallible;
}
impl<Uart: Instance, const N: usize> RxAsync<Uart, N> {
/// Create a new asynchronous receiver.
///
/// The passed [heapless::spsc::Consumer] will be used to asynchronously receive data which
/// is filled by the interrupt handler.
pub fn new(mut rx: Rx<Uart>, queue: heapless::spsc::Consumer<'static, u8, N>) -> Self {
rx.disable_interrupts();
rx.disable();
rx.clear_fifo();
// Enable those together.
critical_section::with(|_| {
rx.enable_interrupts();
rx.enable();
});
Self { rx, queue }
}
}
impl<Uart: Instance, const N: usize> embedded_io_async::Read for RxAsync<Uart, N> {
async fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
// Need to wait for the IRQ to read data and set this flag. If the queue is not
// empty, we can read data immediately.
if self.queue.len() == 0 {
RX_HAS_DATA[Uart::IDX as usize].store(false, Ordering::Relaxed);
}
let _guard = ActiveReadGuard(Uart::IDX as usize);
let mut handle_data_in_queue = |consumer: &mut heapless::spsc::Consumer<'static, u8, N>| {
let data_to_read = consumer.len().min(buf.len());
for byte in buf.iter_mut().take(data_to_read) {
// We own the consumer and we checked that the amount of data is guaranteed to be available.
*byte = unsafe { consumer.dequeue_unchecked() };
}
data_to_read
};
let fut = RxFuture::new(&mut self.rx);
// Data is available, so read that data immediately.
let read_data = handle_data_in_queue(&mut self.queue);
if read_data > 0 {
return Ok(read_data);
}
// Await data.
let _ = fut.await;
Ok(handle_data_in_queue(&mut self.queue))
}
}
/// Core data structure to allow asynchrnous UART reception.
///
/// If the ring buffer becomes full, the oldest data will be overwritten when using the
/// [on_interrupt_uart_a_overwriting] and [on_interrupt_uart_b_overwriting] interrupt handlers.
pub struct RxAsyncSharedConsumer<Uart: Instance, const N: usize> {
rx: Rx<Uart>,
queue: &'static Mutex<RefCell<Option<Consumer<'static, u8, N>>>>,
}
impl<Uart: Instance, const N: usize> ErrorType for RxAsyncSharedConsumer<Uart, N> {
/// Error reporting is done using atomic booleans and the [get_and_clear_errors] function.
type Error = Infallible;
}
impl<Uart: Instance, const N: usize> RxAsyncSharedConsumer<Uart, N> {
/// Create a new asynchronous receiver.
///
/// The passed shared [heapless::spsc::Consumer] will be used to asynchronously receive data
/// which is filled by the interrupt handler. The shared property allows using it in the
/// interrupt handler to overwrite old data.
pub fn new(
mut rx: Rx<Uart>,
queue: &'static Mutex<RefCell<Option<heapless::spsc::Consumer<'static, u8, N>>>>,
) -> Self {
rx.disable_interrupts();
rx.disable();
rx.clear_fifo();
// Enable those together.
critical_section::with(|_| {
rx.enable_interrupts();
rx.enable();
});
Self { rx, queue }
}
}
impl<Uart: Instance, const N: usize> embedded_io_async::Read for RxAsyncSharedConsumer<Uart, N> {
async fn read(&mut self, buf: &mut [u8]) -> Result<usize, Self::Error> {
// Need to wait for the IRQ to read data and set this flag. If the queue is not
// empty, we can read data immediately.
critical_section::with(|cs| {
let queue = self.queue.borrow(cs);
if queue.borrow().as_ref().unwrap().len() == 0 {
RX_HAS_DATA[Uart::IDX as usize].store(false, Ordering::Relaxed);
}
});
let _guard = ActiveReadGuard(Uart::IDX as usize);
let mut handle_data_in_queue = || {
critical_section::with(|cs| {
let mut consumer_ref = self.queue.borrow(cs).borrow_mut();
let consumer = consumer_ref.as_mut().unwrap();
let data_to_read = consumer.len().min(buf.len());
for byte in buf.iter_mut().take(data_to_read) {
// We own the consumer and we checked that the amount of data is guaranteed to be available.
*byte = unsafe { consumer.dequeue_unchecked() };
}
data_to_read
})
};
let fut = RxFuture::new(&mut self.rx);
// Data is available, so read that data immediately.
let read_data = handle_data_in_queue();
if read_data > 0 {
return Ok(read_data);
}
// Await data.
let _ = fut.await;
let read_data = handle_data_in_queue();
Ok(read_data)
}
}