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Merge pull request #260 from Liamolucko/nrf-timer

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Add an nRF Timer driver
This commit is contained in:
Dario Nieuwenhuis 2021-06-29 07:37:06 +02:00 committed by GitHub
commit d49adc98be
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3 changed files with 338 additions and 48 deletions
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40
embassy-nrf/src/buffered_uarte.rs
View File

@ -15,7 +15,9 @@ use crate::gpio::sealed::Pin as _;
use crate::gpio::{OptionalPin as GpioOptionalPin, Pin as GpioPin};
use crate::pac;
use crate::ppi::{AnyConfigurableChannel, ConfigurableChannel, Event, Ppi, Task};
use crate::timer::Frequency;
use crate::timer::Instance as TimerInstance;
use crate::timer::Timer;
use crate::uarte::{Config, Instance as UarteInstance};
// Re-export SVD variants to allow user to directly set values
@ -35,7 +37,7 @@ enum TxState {
struct State<'d, U: UarteInstance, T: TimerInstance> {
phantom: PhantomData<&'d mut U>,
timer: T,
timer: Timer<'d, T>,
_ppi_ch1: Ppi<'d, AnyConfigurableChannel>,
_ppi_ch2: Ppi<'d, AnyConfigurableChannel>,
@ -76,10 +78,11 @@ impl<'d, U: UarteInstance, T: TimerInstance> BufferedUarte<'d, U, T> {
rx_buffer: &'d mut [u8],
tx_buffer: &'d mut [u8],
) -> Self {
unborrow!(timer, ppi_ch1, ppi_ch2, irq, rxd, txd, cts, rts);
unborrow!(ppi_ch1, ppi_ch2, irq, rxd, txd, cts, rts);
let r = U::regs();
let rt = timer.regs();
let mut timer = Timer::new_irqless(timer);
rxd.conf().write(|w| w.input().connect().drive().h0h1());
r.psel.rxd.write(|w| unsafe { w.bits(rxd.psel_bits()) });
@ -133,25 +136,19 @@ impl<'d, U: UarteInstance, T: TimerInstance> BufferedUarte<'d, U, T> {
// This gives us the amount of 16M ticks for 20 bits.
let timeout = 0x8000_0000 / (config.baudrate as u32 / 40);
rt.tasks_stop.write(|w| unsafe { w.bits(1) });
rt.bitmode.write(|w| w.bitmode()._32bit());
rt.prescaler.write(|w| unsafe { w.prescaler().bits(0) });
rt.cc[0].write(|w| unsafe { w.bits(timeout) });
rt.mode.write(|w| w.mode().timer());
rt.shorts.write(|w| {
w.compare0_clear().set_bit();
w.compare0_stop().set_bit();
w
});
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(ppi_ch1.degrade_configurable());
ppi_ch1.set_event(Event::from_reg(&r.events_rxdrdy));
ppi_ch1.set_task(Task::from_reg(&rt.tasks_clear));
ppi_ch1.set_fork_task(Task::from_reg(&rt.tasks_start));
ppi_ch1.set_task(timer.task_clear());
ppi_ch1.set_fork_task(timer.task_start());
ppi_ch1.enable();
let mut ppi_ch2 = Ppi::new(ppi_ch2.degrade_configurable());
ppi_ch2.set_event(Event::from_reg(&rt.events_compare[0]));
ppi_ch2.set_event(timer.cc(0).event_compare());
ppi_ch2.set_task(Task::from_reg(&r.tasks_stoprx));
ppi_ch2.enable();
@ -181,11 +178,10 @@ impl<'d, U: UarteInstance, T: TimerInstance> BufferedUarte<'d, U, T> {
inner.as_mut().register_interrupt();
inner.with(|state, _irq| {
let r = U::regs();
let rt = state.timer.regs();
let timeout = 0x8000_0000 / (baudrate as u32 / 40);
rt.cc[0].write(|w| unsafe { w.bits(timeout) });
rt.tasks_clear.write(|w| unsafe { w.bits(1) });
state.timer.cc(0).write(timeout);
state.timer.clear();
r.baudrate.write(|w| w.baudrate().variant(baudrate));
});
@ -268,11 +264,10 @@ impl<'d, U: UarteInstance, T: TimerInstance> AsyncWrite for BufferedUarte<'d, U,
impl<'a, U: UarteInstance, T: TimerInstance> Drop for State<'a, U, T> {
fn drop(&mut self) {
let r = U::regs();
let rt = self.timer.regs();
// TODO this probably deadlocks. do like Uarte instead.
rt.tasks_stop.write(|w| unsafe { w.bits(1) });
self.timer.stop();
if let RxState::Receiving = self.rx_state {
r.tasks_stoprx.write(|w| unsafe { w.bits(1) });
}
@ -293,7 +288,6 @@ impl<'a, U: UarteInstance, T: TimerInstance> PeripheralState for State<'a, U, T>
fn on_interrupt(&mut self) {
trace!("irq: start");
let r = U::regs();
let rt = self.timer.regs();
loop {
match self.rx_state {
@ -330,7 +324,7 @@ impl<'a, U: UarteInstance, T: TimerInstance> PeripheralState for State<'a, U, T>
RxState::Receiving => {
trace!(" irq_rx: in state receiving");
if r.events_endrx.read().bits() != 0 {
rt.tasks_stop.write(|w| unsafe { w.bits(1) });
self.timer.stop();
let n: usize = r.rxd.amount.read().amount().bits() as usize;
trace!(" irq_rx: endrx {:?}", n);

310
embassy-nrf/src/timer.rs
View File

@ -1,15 +1,30 @@
#![macro_use]
use core::marker::PhantomData;
use core::task::Poll;
use embassy::interrupt::Interrupt;
use embassy::interrupt::InterruptExt;
use embassy::util::OnDrop;
use embassy::util::Unborrow;
use embassy_extras::unborrow;
use futures::future::poll_fn;
use crate::pac;
use crate::ppi::Event;
use crate::ppi::Task;
pub(crate) mod sealed {
use embassy::util::AtomicWaker;
use super::*;
pub trait Instance {
fn regs(&self) -> &pac::timer0::RegisterBlock;
/// The number of CC registers this instance has.
const CCS: usize;
fn regs() -> &'static pac::timer0::RegisterBlock;
/// Storage for the waker for CC register `n`.
fn waker(n: usize) -> &'static AtomicWaker;
}
pub trait ExtendedInstance {}
}
@ -20,19 +35,306 @@ pub trait Instance: Unborrow<Target = Self> + sealed::Instance + 'static {
pub trait ExtendedInstance: Instance + sealed::ExtendedInstance {}
macro_rules! impl_timer {
($type:ident, $pac_type:ident, $irq:ident) => {
($type:ident, $pac_type:ident, $irq:ident, $ccs:literal) => {
impl crate::timer::sealed::Instance for peripherals::$type {
fn regs(&self) -> &pac::timer0::RegisterBlock {
const CCS: usize = $ccs;
fn regs() -> &'static pac::timer0::RegisterBlock {
unsafe { &*(pac::$pac_type::ptr() as *const pac::timer0::RegisterBlock) }
}
fn waker(n: usize) -> &'static ::embassy::util::AtomicWaker {
use ::embassy::util::AtomicWaker;
const NEW_AW: AtomicWaker = AtomicWaker::new();
static WAKERS: [AtomicWaker; $ccs] = [NEW_AW; $ccs];
&WAKERS[n]
}
}
impl crate::timer::Instance for peripherals::$type {
type Interrupt = crate::interrupt::$irq;
}
};
($type:ident, $pac_type:ident, $irq:ident) => {
impl_timer!($type, $pac_type, $irq, 4);
};
($type:ident, $pac_type:ident, $irq:ident, extended) => {
impl_timer!($type, $pac_type, $irq);
impl_timer!($type, $pac_type, $irq, 6);
impl crate::timer::sealed::ExtendedInstance for peripherals::$type {}
impl crate::timer::ExtendedInstance for peripherals::$type {}
};
}
#[repr(u8)]
pub enum Frequency {
// I'd prefer not to prefix these with `F`, but Rust identifiers can't start with digits.
F16MHz = 0,
F8MHz = 1,
F4MHz = 2,
F2MHz = 3,
F1MHz = 4,
F500kHz = 5,
F250kHz = 6,
F125kHz = 7,
F62500Hz = 8,
F31250Hz = 9,
}
/// nRF Timer driver.
///
/// The timer has an internal counter, which is incremented for every tick of the timer.
/// The counter is 32-bit, so it wraps back to 0 at 4294967296.
///
/// It has either 4 or 6 Capture/Compare registers, which can be used to capture the current state of the counter
/// or trigger an event when the counter reaches a certain value.
pub struct Timer<'d, T: Instance> {
phantom: PhantomData<&'d mut T>,
}
impl<'d, T: Instance> Timer<'d, T> {
pub fn new(
timer: impl Unborrow<Target = T> + 'd,
irq: impl Unborrow<Target = T::Interrupt> + 'd,
) -> Self {
unborrow!(irq);
irq.set_handler(Self::on_interrupt);
irq.unpend();
irq.enable();
Self::new_irqless(timer)
}
/// Create a `Timer` without an interrupt, meaning `Cc::wait` won't work.
///
/// This is used by `Uarte` internally.
pub(crate) fn new_irqless(_timer: impl Unborrow<Target = T> + 'd) -> Self {
let regs = T::regs();
let mut this = Self {
phantom: PhantomData,
};
// Stop the timer before doing anything else,
// since changing BITMODE while running can cause 'unpredictable behaviour' according to the specification.
this.stop();
// Set the instance to timer mode.
regs.mode.write(|w| w.mode().timer());
// Make the counter's max value as high as possible.
// TODO: is there a reason someone would want to set this lower?
regs.bitmode.write(|w| w.bitmode()._32bit());
// Initialize the counter at 0.
this.clear();
// Default to the max frequency of the lower power clock
this.set_frequency(Frequency::F1MHz);
for n in 0..T::CCS {
let cc = this.cc(n);
// Initialize all the shorts as disabled.
cc.unshort_compare_clear();
cc.unshort_compare_stop();
// Initialize the CC registers as 0.
cc.write(0);
}
this
}
/// Starts the timer.
pub fn start(&self) {
T::regs().tasks_start.write(|w| unsafe { w.bits(1) })
}
/// Stops the timer.
pub fn stop(&self) {
T::regs().tasks_stop.write(|w| unsafe { w.bits(1) })
}
/// Reset the timer's counter to 0.
pub fn clear(&self) {
T::regs().tasks_clear.write(|w| unsafe { w.bits(1) })
}
/// Returns the START task, for use with PPI.
///
/// When triggered, this task starts the timer.
pub fn task_start(&self) -> Task {
Task::from_reg(&T::regs().tasks_start)
}
/// Returns the STOP task, for use with PPI.
///
/// When triggered, this task stops the timer.
pub fn task_stop(&self) -> Task {
Task::from_reg(&T::regs().tasks_stop)
}
/// Returns the CLEAR task, for use with PPI.
///
/// When triggered, this task resets the timer's counter to 0.
pub fn task_clear(&self) -> Task {
Task::from_reg(&T::regs().tasks_clear)
}
/// Change the timer's frequency.
///
/// This will stop the timer if it isn't already stopped,
/// because the timer may exhibit 'unpredictable behaviour' if it's frequency is changed while it's running.
pub fn set_frequency(&self, frequency: Frequency) {
self.stop();
T::regs()
.prescaler
// SAFETY: `frequency` is a variant of `Frequency`,
// whose values are all in the range of 0-9 (the valid range of `prescaler`).
.write(|w| unsafe { w.prescaler().bits(frequency as u8) })
}
fn on_interrupt(_: *mut ()) {
let regs = T::regs();
for n in 0..T::CCS {
if regs.events_compare[n].read().bits() != 0 {
// Clear the interrupt, otherwise the interrupt will be repeatedly raised as soon as the interrupt handler exits.
// We can't clear the event, because it's used to poll whether the future is done or still pending.
regs.intenclr
.modify(|r, w| unsafe { w.bits(r.bits() | (1 << (16 + n))) });
T::waker(n).wake();
}
}
}
/// Returns this timer's `n`th CC register.
///
/// # Panics
/// Panics if `n` >= the number of CC registers this timer has (4 for a normal timer, 6 for an extended timer).
pub fn cc(&mut self, n: usize) -> Cc<T> {
if n >= T::CCS {
panic!(
"Cannot get CC register {} of timer with {} CC registers.",
n,
T::CCS
);
}
Cc {
n,
phantom: PhantomData,
}
}
}
/// A representation of a timer's Capture/Compare (CC) register.
///
/// A CC register holds a 32-bit value.
/// This is used either to store a capture of the timer's current count, or to specify the value for the timer to compare against.
///
/// The timer will fire the register's COMPARE event when its counter reaches the value stored in the register.
/// When the register's CAPTURE task is triggered, the timer will store the current value of its counter in the register
pub struct Cc<'a, T: Instance> {
n: usize,
phantom: PhantomData<&'a mut T>,
}
impl<'a, T: Instance> Cc<'a, T> {
/// Get the current value stored in the register.
pub fn read(&self) -> u32 {
T::regs().cc[self.n].read().cc().bits()
}
/// Set the value stored in the register.
///
/// `event_compare` will fire when the timer's counter reaches this value.
pub fn write(&self, value: u32) {
// SAFETY: there are no invalid values for the CC register.
T::regs().cc[self.n].write(|w| unsafe { w.cc().bits(value) })
}
/// Capture the current value of the timer's counter in this register, and return it.
pub fn capture(&self) -> u32 {
T::regs().tasks_capture[self.n].write(|w| unsafe { w.bits(1) });
self.read()
}
/// Returns this CC register's CAPTURE task, for use with PPI.
///
/// When triggered, this task will capture the current value of the timer's counter in this register.
pub fn task_capture(&self) -> Task {
Task::from_reg(&T::regs().tasks_capture[self.n])
}
/// Returns this CC register's COMPARE event, for use with PPI.
///
/// This event will fire when the timer's counter reaches the value in this CC register.
pub fn event_compare(&self) -> Event {
Event::from_reg(&T::regs().events_compare[self.n])
}
/// Enable the shortcut between this CC register's COMPARE event and the timer's CLEAR task.
///
/// This means that when the COMPARE event is fired, the CLEAR task will be triggered.
///
/// So, when the timer's counter reaches the value stored in this register, the timer's counter will be reset to 0.
pub fn short_compare_clear(&self) {
T::regs()
.shorts
.modify(|r, w| unsafe { w.bits(r.bits() | (1 << self.n)) })
}
/// Disable the shortcut between this CC register's COMPARE event and the timer's CLEAR task.
pub fn unshort_compare_clear(&self) {
T::regs()
.shorts
.modify(|r, w| unsafe { w.bits(r.bits() & !(1 << self.n)) })
}
/// Enable the shortcut between this CC register's COMPARE event and the timer's STOP task.
///
/// This means that when the COMPARE event is fired, the STOP task will be triggered.
///
/// So, when the timer's counter reaches the value stored in this register, the timer will stop counting up.
pub fn short_compare_stop(&self) {
T::regs()
.shorts
.modify(|r, w| unsafe { w.bits(r.bits() | (1 << (8 + self.n))) })
}
/// Disable the shortcut between this CC register's COMPARE event and the timer's STOP task.
pub fn unshort_compare_stop(&self) {
T::regs()
.shorts
.modify(|r, w| unsafe { w.bits(r.bits() & !(1 << (8 + self.n))) })
}
/// Wait until the timer's counter reaches the value stored in this register.
///
/// This requires a mutable reference so that this task's waker cannot be overwritten by a second call to `wait`.
pub async fn wait(&mut self) {
let regs = T::regs();
// Enable the interrupt for this CC's COMPARE event.
regs.intenset
.modify(|r, w| unsafe { w.bits(r.bits() | (1 << (16 + self.n))) });
// Disable the interrupt if the future is dropped.
let on_drop = OnDrop::new(|| {
regs.intenclr
.modify(|r, w| unsafe { w.bits(r.bits() | (1 << (16 + self.n))) });
});
poll_fn(|cx| {
T::waker(self.n).register(cx.waker());
if regs.events_compare[self.n].read().bits() != 0 {
// Reset the register for next time
regs.events_compare[self.n].reset();
Poll::Ready(())
} else {
Poll::Pending
}
})
.await;
// The interrupt was already disabled in the interrupt handler, so there's no need to disable it again.
on_drop.defuse();
}
}

36
embassy-nrf/src/uarte.rs
View File

@ -18,7 +18,9 @@ use crate::gpio::{self, OptionalPin as GpioOptionalPin, Pin as GpioPin};
use crate::interrupt::Interrupt;
use crate::pac;
use crate::ppi::{AnyConfigurableChannel, ConfigurableChannel, Event, Ppi, Task};
use crate::timer::Frequency;
use crate::timer::Instance as TimerInstance;
use crate::timer::Timer;
// 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};
@ -287,7 +289,7 @@ impl<'d, T: Instance> Write for Uarte<'d, T> {
/// allowing it to implement the ReadUntilIdle trait.
pub struct UarteWithIdle<'d, U: Instance, T: TimerInstance> {
uarte: Uarte<'d, U>,
timer: T,
timer: Timer<'d, T>,
ppi_ch1: Ppi<'d, AnyConfigurableChannel>,
_ppi_ch2: Ppi<'d, AnyConfigurableChannel>,
}
@ -316,11 +318,11 @@ impl<'d, U: Instance, T: TimerInstance> UarteWithIdle<'d, U, T> {
) -> Self {
let baudrate = config.baudrate;
let uarte = Uarte::new(uarte, irq, rxd, txd, cts, rts, config);
let mut timer = Timer::new_irqless(timer);
unborrow!(timer, ppi_ch1, ppi_ch2);
unborrow!(ppi_ch1, ppi_ch2);
let r = U::regs();
let rt = timer.regs();
// BAUDRATE register values are `baudrate * 2^32 / 16000000`
// source: https://devzone.nordicsemi.com/f/nordic-q-a/391/uart-baudrate-register-values
@ -330,25 +332,19 @@ impl<'d, U: Instance, T: TimerInstance> UarteWithIdle<'d, U, T> {
// This gives us the amount of 16M ticks for 20 bits.
let timeout = 0x8000_0000 / (baudrate as u32 / 40);
rt.tasks_stop.write(|w| unsafe { w.bits(1) });
rt.bitmode.write(|w| w.bitmode()._32bit());
rt.prescaler.write(|w| unsafe { w.prescaler().bits(0) });
rt.cc[0].write(|w| unsafe { w.bits(timeout) });
rt.mode.write(|w| w.mode().timer());
rt.shorts.write(|w| {
w.compare0_clear().set_bit();
w.compare0_stop().set_bit();
w
});
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(ppi_ch1.degrade_configurable());
ppi_ch1.set_event(Event::from_reg(&r.events_rxdrdy));
ppi_ch1.set_task(Task::from_reg(&rt.tasks_clear));
ppi_ch1.set_fork_task(Task::from_reg(&rt.tasks_start));
ppi_ch1.set_task(timer.task_clear());
ppi_ch1.set_fork_task(timer.task_start());
ppi_ch1.enable();
let mut ppi_ch2 = Ppi::new(ppi_ch2.degrade_configurable());
ppi_ch2.set_event(Event::from_reg(&rt.events_compare[0]));
ppi_ch2.set_event(timer.cc(0).event_compare());
ppi_ch2.set_task(Task::from_reg(&r.tasks_stoprx));
ppi_ch2.enable();
@ -373,12 +369,10 @@ impl<'d, U: Instance, T: TimerInstance> ReadUntilIdle for UarteWithIdle<'d, U, T
let r = U::regs();
let s = U::state();
let rt = self.timer.regs();
let drop = OnDrop::new(move || {
let drop = OnDrop::new(|| {
info!("read drop: stopping");
rt.tasks_stop.write(|w| unsafe { w.bits(1) });
self.timer.stop();
r.intenclr.write(|w| w.endrx().clear());
r.events_rxto.reset();
@ -413,7 +407,7 @@ impl<'d, U: Instance, T: TimerInstance> ReadUntilIdle for UarteWithIdle<'d, U, T
let n = r.rxd.amount.read().amount().bits() as usize;
// Stop timer
rt.tasks_stop.write(|w| unsafe { w.bits(1) });
self.timer.stop();
r.events_rxstarted.reset();
drop.defuse();