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first working embassy example
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This commit is contained in:
Robin Müller 2024-09-17 20:01:56 +02:00
parent d231905aca
commit 857b59c3c2
Signed by: muellerr
GPG Key ID: A649FB78196E3849
4 changed files with 335 additions and 310 deletions
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7
examples/embassy/Cargo.toml
View File

@ -13,7 +13,7 @@ panic-rtt-target = { version = "0.1" }
critical-section = "1"
embassy-sync = { version = "0.6.0" }
embassy-time = { version = "0.3.2", features = ["tick-hz-1_000"] }
embassy-time = { version = "0.3.2" }
embassy-time-driver = { version = "0.1" }
[dependencies.once_cell]
@ -33,3 +33,8 @@ features = [
[dependencies.va416xx-hal]
path = "../../va416xx-hal"
features = ["va41630"]
[features]
default = ["ticks-hz-1_000"]
ticks-hz-1_000 = ["embassy-time/tick-hz-1_000"]
ticks-hz-32_768 = ["embassy-time/tick-hz-32_768"]

309
examples/embassy/src/lib.rs
View File

@ -1,309 +1,4 @@
#![no_std]
use core::{
cell::Cell,
mem, ptr,
sync::atomic::{AtomicU32, AtomicU8, Ordering},
};
use critical_section::CriticalSection;
use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
use embassy_sync::blocking_mutex::Mutex;
pub mod time_driver;
use embassy_time_driver::{time_driver_impl, AlarmHandle, Driver, TICK_HZ};
use rtt_target::rprintln;
use va416xx_hal::{
clock::Clocks,
enable_interrupt,
irq_router::enable_and_init_irq_router,
pac::{self, interrupt},
pwm::{assert_tim_reset_for_two_cycles, enable_tim_clk, ValidTim},
};
pub type TimekeeperClk = pac::Tim15;
pub type AlarmClk0 = pac::Tim14;
pub type AlarmClk1 = pac::Tim13;
pub type AlarmClk2 = pac::Tim12;
// Uses integer division to get a margin of 75 % of the base value added on the ticks
const fn three_quarters_of_period(period: u64) -> u64 {
(period * 3) / 4
}
/// Initialization method for embassy
///
/// # Safety
/// This has to be called once at initialization time to initiate the time driver for
/// embassy.
pub unsafe fn init(
syscfg: &mut pac::Sysconfig,
irq_router: &pac::IrqRouter,
timekeeper: TimekeeperClk,
alarm: AlarmClk0,
clocks: &Clocks,
) {
enable_and_init_irq_router(syscfg, irq_router);
DRIVER.init(syscfg, timekeeper, alarm, clocks)
}
const fn alarm_tim(idx: usize) -> &'static pac::tim0::RegisterBlock {
// Safety: This is a static memory-mapped peripheral.
match idx {
0 => unsafe { &*AlarmClk0::ptr() },
1 => unsafe { &*AlarmClk1::ptr() },
2 => unsafe { &*AlarmClk2::ptr() },
_ => {
panic!("invalid alarm timer index")
}
}
}
const fn timekeeping_tim() -> &'static pac::tim0::RegisterBlock {
// Safety: This is a memory-mapped peripheral.
unsafe { &*TimekeeperClk::ptr() }
}
struct AlarmState {
timestamp: Cell<u64>,
// This is really a Option<(fn(*mut ()), *mut ())>
// but fn pointers aren't allowed in const yet
callback: Cell<*const ()>,
ctx: Cell<*mut ()>,
}
impl AlarmState {
const fn new() -> Self {
Self {
timestamp: Cell::new(u64::MAX),
callback: Cell::new(ptr::null()),
ctx: Cell::new(ptr::null_mut()),
}
}
}
unsafe impl Send for AlarmState {}
const ALARM_COUNT: usize = 1;
pub struct TimerDriverEmbassy {
periods: AtomicU32,
alarm_count: AtomicU8,
/// Timestamp at which to fire alarm. u64::MAX if no alarm is scheduled.
alarms: Mutex<CriticalSectionRawMutex, [AlarmState; ALARM_COUNT]>,
}
impl TimerDriverEmbassy {
fn init(
&self,
syscfg: &mut pac::Sysconfig,
timekeeper: TimekeeperClk,
alarm_tim: AlarmClk0,
clocks: &Clocks,
) {
enable_tim_clk(syscfg, TimekeeperClk::TIM_ID);
assert_tim_reset_for_two_cycles(syscfg, TimekeeperClk::TIM_ID);
let rst_val = (TimekeeperClk::clock(clocks).raw() / TICK_HZ as u32) - 1;
timekeeper.rst_value().write(|w| unsafe { w.bits(rst_val) });
// Decrementing counter.
timekeeper.cnt_value().write(|w| unsafe { w.bits(rst_val) });
// Switch on. Timekeeping should always be done.
unsafe {
enable_interrupt(TimekeeperClk::IRQ);
}
timekeeper.ctrl().modify(|_, w| w.irq_enb().set_bit());
timekeeper.enable().write(|w| unsafe { w.bits(1) });
enable_tim_clk(syscfg, AlarmClk0::TIM_ID);
assert_tim_reset_for_two_cycles(syscfg, AlarmClk0::TIM_ID);
// Explicitely disable alarm timer until needed.
alarm_tim.ctrl().modify(|_, w| {
w.irq_enb().clear_bit();
w.enable().clear_bit()
});
// Enable general interrupts. The IRQ enable of the peripheral remains cleared.
unsafe {
enable_interrupt(AlarmClk0::IRQ);
}
}
// Should be called inside the IRQ of the timekeeper timer.
fn on_interrupt_timekeeping(&self) {
self.next_period();
}
// Should be called inside the IRQ of the alarm timer.
fn on_interrupt_alarm(&self, idx: usize) {
critical_section::with(|cs| {
if self.alarms.borrow(cs)[idx].timestamp.get() <= self.now() {
self.trigger_alarm(idx, cs)
}
})
}
fn next_period(&self) {
let period = self.periods.fetch_add(1, Ordering::AcqRel) + 1;
let rst_val = timekeeping_tim().rst_value().read().bits() as u64;
let t = period as u64 * rst_val;
critical_section::with(|cs| {
for i in 0..ALARM_COUNT {
let alarm = &self.alarms.borrow(cs)[i];
let at = alarm.timestamp.get();
let alarm_tim = alarm_tim(0);
if at < t {
self.trigger_alarm(i, cs);
} else if at - t <= u32::MAX as u64 {
alarm_tim.enable().write(|w| unsafe { w.bits(0) });
alarm_tim
.cnt_value()
.write(|w| unsafe { w.bits((at - t) as u32) });
alarm_tim.ctrl().modify(|_, w| w.irq_enb().set_bit());
alarm_tim.enable().write(|w| unsafe { w.bits(1) })
}
}
})
}
fn get_alarm<'a>(&'a self, cs: CriticalSection<'a>, alarm: AlarmHandle) -> &'a AlarmState {
// safety: we're allowed to assume the AlarmState is created by us, and
// we never create one that's out of bounds.
unsafe { self.alarms.borrow(cs).get_unchecked(alarm.id() as usize) }
}
fn trigger_alarm(&self, n: usize, cs: CriticalSection) {
alarm_tim(n).ctrl().modify(|_, w| {
w.irq_enb().clear_bit();
w.enable().clear_bit()
});
let alarm = &self.alarms.borrow(cs)[n];
// Setting the maximum value disables the alarm.
alarm.timestamp.set(u64::MAX);
// Call after clearing alarm, so the callback can set another alarm.
// safety:
// - we can ignore the possiblity of `f` being unset (null) because of the safety contract of `allocate_alarm`.
// - other than that we only store valid function pointers into alarm.callback
let f: fn(*mut ()) = unsafe { mem::transmute(alarm.callback.get()) };
f(alarm.ctx.get());
}
}
impl Driver for TimerDriverEmbassy {
fn now(&self) -> u64 {
let mut period1: u32;
let mut period2: u32;
let mut counter_val: u32;
let rst_val = timekeeping_tim().rst_value().read().bits();
loop {
// Acquire ensures that we get the latest value of `periods` and
// no instructions can be reordered before the load.
period1 = self.periods.load(Ordering::Acquire);
counter_val = rst_val - timekeeping_tim().cnt_value().read().bits();
// Double read to protect against race conditions when the counter is overflowing.
period2 = self.periods.load(Ordering::Relaxed);
if period1 == period2 {
return (period1 as u64 * rst_val as u64) + counter_val as u64;
}
}
}
unsafe fn allocate_alarm(&self) -> Option<AlarmHandle> {
let id = self
.alarm_count
.fetch_update(Ordering::AcqRel, Ordering::Acquire, |x| {
if x < ALARM_COUNT as u8 {
Some(x + 1)
} else {
None
}
});
match id {
Ok(id) => Some(AlarmHandle::new(id)),
Err(_) => None,
}
}
fn set_alarm_callback(
&self,
alarm: embassy_time_driver::AlarmHandle,
callback: fn(*mut ()),
ctx: *mut (),
) {
critical_section::with(|cs| {
let alarm = self.get_alarm(cs, alarm);
alarm.callback.set(callback as *const ());
alarm.ctx.set(ctx);
})
}
fn set_alarm(&self, alarm: embassy_time_driver::AlarmHandle, timestamp: u64) -> bool {
critical_section::with(|cs| {
let n = alarm.id();
let alarm_tim = alarm_tim(n.into());
alarm_tim.ctrl().modify(|_, w| {
w.irq_enb().clear_bit();
w.enable().clear_bit()
});
let alarm = self.get_alarm(cs, alarm);
alarm.timestamp.set(timestamp);
let t = self.now();
if timestamp <= t {
alarm.timestamp.set(u64::MAX);
return false;
}
// If it hasn't triggered yet, setup the relevant reset value, regardless of whether
// the interrupts are enabled or not. When they are enabled at a later point, the
// right value is already set.
// If the timestamp is in the next few ticks, add a bit of buffer to be sure the alarm
// is not missed.
//
// This means that an alarm can be delayed for up to 2 ticks (from t+1 to t+3), but this is allowed
// by the Alarm trait contract. What's not allowed is triggering alarms *before* their scheduled time,
// and we don't do that here.
let safe_timestamp = timestamp.max(t + 3);
let diff = safe_timestamp - t;
alarm_tim.rst_value().write(|w| unsafe { w.bits(u32::MAX) });
if diff <= u32::MAX as u64 {
alarm_tim
.cnt_value()
.write(|w| unsafe { w.bits(diff as u32) });
alarm_tim.ctrl().modify(|_, w| w.irq_enb().set_bit());
alarm_tim.enable().write(|w| unsafe { w.bits(1) });
}
// If it's too far in the future, don't enable timer yet.
// It will be enabled later by `next_period`.
true
})
}
}
time_driver_impl!(
static DRIVER: TimerDriverEmbassy = TimerDriverEmbassy {
periods: AtomicU32::new(0),
alarm_count: AtomicU8::new(0),
alarms: Mutex::const_new(CriticalSectionRawMutex::new(), [AlarmState::new(); ALARM_COUNT])
});
#[interrupt]
#[allow(non_snake_case)]
fn TIM15() {
DRIVER.on_interrupt_timekeeping()
}
#[interrupt]
#[allow(non_snake_case)]
fn TIM14() {
DRIVER.on_interrupt_alarm(0)
}
pub use time_driver::init;

6
examples/embassy/src/main.rs
View File

@ -1,7 +1,7 @@
#![no_std]
#![no_main]
use embassy_executor::Spawner;
use embassy_time::Timer;
use embassy_time::{Duration, Instant, Ticker};
use embedded_hal::digital::StatefulOutputPin;
use panic_rtt_target as _;
use rtt_target::{rprintln, rtt_init_print};
@ -37,8 +37,10 @@ async fn main(_spawner: Spawner) {
};
let portg = PinsG::new(&mut dp.sysconfig, dp.portg);
let mut led = portg.pg5.into_readable_push_pull_output();
let mut ticker = Ticker::every(Duration::from_secs(1));
loop {
Timer::after_secs(1).await;
ticker.next().await;
rprintln!("Current time: {}", Instant::now().as_secs());
led.toggle().ok();
}
}

323
examples/embassy/src/time_driver.rs Normal file
View File

@ -0,0 +1,323 @@
//! This is a sample time driver implementation for the VA416xx family of devices, supporting
//! one alarm and requiring/reserving 2 TIM peripherals. You could adapt this implementation to
//! support more alarms.
use core::{
cell::Cell,
mem, ptr,
sync::atomic::{AtomicU32, AtomicU8, Ordering},
};
use critical_section::CriticalSection;
use embassy_sync::blocking_mutex::raw::CriticalSectionRawMutex;
use embassy_sync::blocking_mutex::Mutex;
use embassy_time_driver::{time_driver_impl, AlarmHandle, Driver, TICK_HZ};
use once_cell::sync::OnceCell;
use va416xx_hal::{
clock::Clocks,
enable_interrupt,
irq_router::enable_and_init_irq_router,
pac::{self, interrupt},
pwm::{assert_tim_reset_for_two_cycles, enable_tim_clk, ValidTim},
};
pub type TimekeeperClk = pac::Tim15;
pub type AlarmClk0 = pac::Tim14;
pub type AlarmClk1 = pac::Tim13;
pub type AlarmClk2 = pac::Tim12;
/// Initialization method for embassy
///
/// # Safety
/// This has to be called once at initialization time to initiate the time driver for
/// embassy.
pub unsafe fn init(
syscfg: &mut pac::Sysconfig,
irq_router: &pac::IrqRouter,
timekeeper: TimekeeperClk,
alarm: AlarmClk0,
clocks: &Clocks,
) {
enable_and_init_irq_router(syscfg, irq_router);
DRIVER.init(syscfg, timekeeper, alarm, clocks)
}
const fn alarm_tim(idx: usize) -> &'static pac::tim0::RegisterBlock {
// Safety: This is a static memory-mapped peripheral.
match idx {
0 => unsafe { &*AlarmClk0::ptr() },
1 => unsafe { &*AlarmClk1::ptr() },
2 => unsafe { &*AlarmClk2::ptr() },
_ => {
panic!("invalid alarm timer index")
}
}
}
const fn timekeeping_tim() -> &'static pac::tim0::RegisterBlock {
// Safety: This is a memory-mapped peripheral.
unsafe { &*TimekeeperClk::ptr() }
}
struct AlarmState {
timestamp: Cell<u64>,
// This is really a Option<(fn(*mut ()), *mut ())>
// but fn pointers aren't allowed in const yet
callback: Cell<*const ()>,
ctx: Cell<*mut ()>,
}
impl AlarmState {
const fn new() -> Self {
Self {
timestamp: Cell::new(u64::MAX),
callback: Cell::new(ptr::null()),
ctx: Cell::new(ptr::null_mut()),
}
}
}
unsafe impl Send for AlarmState {}
const ALARM_COUNT: usize = 1;
static SCALE: OnceCell<u64> = OnceCell::new();
pub struct TimerDriverEmbassy {
periods: AtomicU32,
alarm_count: AtomicU8,
/// Timestamp at which to fire alarm. u64::MAX if no alarm is scheduled.
alarms: Mutex<CriticalSectionRawMutex, [AlarmState; ALARM_COUNT]>,
}
impl TimerDriverEmbassy {
fn init(
&self,
syscfg: &mut pac::Sysconfig,
timekeeper: TimekeeperClk,
alarm_tim: AlarmClk0,
clocks: &Clocks,
) {
enable_tim_clk(syscfg, TimekeeperClk::TIM_ID);
assert_tim_reset_for_two_cycles(syscfg, TimekeeperClk::TIM_ID);
// Initiate scale value here. This is required to convert timer ticks back to a timestamp.
SCALE
.set((TimekeeperClk::clock(clocks).raw() / TICK_HZ as u32) as u64)
.unwrap();
timekeeper
.rst_value()
.write(|w| unsafe { w.bits(u32::MAX) });
// Decrementing counter.
timekeeper
.cnt_value()
.write(|w| unsafe { w.bits(u32::MAX) });
// Switch on. Timekeeping should always be done.
unsafe {
enable_interrupt(TimekeeperClk::IRQ);
}
timekeeper.ctrl().modify(|_, w| w.irq_enb().set_bit());
timekeeper.enable().write(|w| unsafe { w.bits(1) });
enable_tim_clk(syscfg, AlarmClk0::TIM_ID);
assert_tim_reset_for_two_cycles(syscfg, AlarmClk0::TIM_ID);
// Explicitely disable alarm timer until needed.
alarm_tim.ctrl().modify(|_, w| {
w.irq_enb().clear_bit();
w.enable().clear_bit()
});
// Enable general interrupts. The IRQ enable of the peripheral remains cleared.
unsafe {
enable_interrupt(AlarmClk0::IRQ);
}
}
// Should be called inside the IRQ of the timekeeper timer.
fn on_interrupt_timekeeping(&self) {
self.next_period();
}
// Should be called inside the IRQ of the alarm timer.
fn on_interrupt_alarm(&self, idx: usize) {
critical_section::with(|cs| {
if self.alarms.borrow(cs)[idx].timestamp.get() <= self.now() {
self.trigger_alarm(idx, cs)
}
})
}
fn next_period(&self) {
let period = self.periods.fetch_add(1, Ordering::AcqRel) + 1;
let t = (period as u64) << 32;
critical_section::with(|cs| {
for i in 0..ALARM_COUNT {
let alarm = &self.alarms.borrow(cs)[i];
let at = alarm.timestamp.get();
let alarm_tim = alarm_tim(0);
if at < t {
self.trigger_alarm(i, cs);
} else {
let remaining_ticks = (at - t) * *SCALE.get().unwrap();
if remaining_ticks <= u32::MAX as u64 {
alarm_tim.enable().write(|w| unsafe { w.bits(0) });
alarm_tim
.cnt_value()
.write(|w| unsafe { w.bits(remaining_ticks as u32) });
alarm_tim.ctrl().modify(|_, w| w.irq_enb().set_bit());
alarm_tim.enable().write(|w| unsafe { w.bits(1) })
}
}
}
})
}
fn get_alarm<'a>(&'a self, cs: CriticalSection<'a>, alarm: AlarmHandle) -> &'a AlarmState {
// safety: we're allowed to assume the AlarmState is created by us, and
// we never create one that's out of bounds.
unsafe { self.alarms.borrow(cs).get_unchecked(alarm.id() as usize) }
}
fn trigger_alarm(&self, n: usize, cs: CriticalSection) {
alarm_tim(n).ctrl().modify(|_, w| {
w.irq_enb().clear_bit();
w.enable().clear_bit()
});
let alarm = &self.alarms.borrow(cs)[n];
// Setting the maximum value disables the alarm.
alarm.timestamp.set(u64::MAX);
// Call after clearing alarm, so the callback can set another alarm.
// safety:
// - we can ignore the possiblity of `f` being unset (null) because of the safety contract of `allocate_alarm`.
// - other than that we only store valid function pointers into alarm.callback
let f: fn(*mut ()) = unsafe { mem::transmute(alarm.callback.get()) };
f(alarm.ctx.get());
}
}
impl Driver for TimerDriverEmbassy {
fn now(&self) -> u64 {
if SCALE.get().is_none() {
return 0;
}
let mut period1: u32;
let mut period2: u32;
let mut counter_val: u32;
loop {
// Acquire ensures that we get the latest value of `periods` and
// no instructions can be reordered before the load.
period1 = self.periods.load(Ordering::Acquire);
counter_val = u32::MAX - timekeeping_tim().cnt_value().read().bits();
// Double read to protect against race conditions when the counter is overflowing.
period2 = self.periods.load(Ordering::Relaxed);
if period1 == period2 {
let now = (((period1 as u64) << 32) | counter_val as u64) / *SCALE.get().unwrap();
return now;
}
}
}
unsafe fn allocate_alarm(&self) -> Option<AlarmHandle> {
let id = self
.alarm_count
.fetch_update(Ordering::AcqRel, Ordering::Acquire, |x| {
if x < ALARM_COUNT as u8 {
Some(x + 1)
} else {
None
}
});
match id {
Ok(id) => Some(AlarmHandle::new(id)),
Err(_) => None,
}
}
fn set_alarm_callback(
&self,
alarm: embassy_time_driver::AlarmHandle,
callback: fn(*mut ()),
ctx: *mut (),
) {
critical_section::with(|cs| {
let alarm = self.get_alarm(cs, alarm);
alarm.callback.set(callback as *const ());
alarm.ctx.set(ctx);
})
}
fn set_alarm(&self, alarm: embassy_time_driver::AlarmHandle, timestamp: u64) -> bool {
if SCALE.get().is_none() {
return false;
}
critical_section::with(|cs| {
let n = alarm.id();
let alarm_tim = alarm_tim(n.into());
alarm_tim.ctrl().modify(|_, w| {
w.irq_enb().clear_bit();
w.enable().clear_bit()
});
let alarm = self.get_alarm(cs, alarm);
alarm.timestamp.set(timestamp);
let t = self.now();
if timestamp <= t {
alarm.timestamp.set(u64::MAX);
return false;
}
// If it hasn't triggered yet, setup the relevant reset value, regardless of whether
// the interrupts are enabled or not. When they are enabled at a later point, the
// right value is already set.
// If the timestamp is in the next few ticks, add a bit of buffer to be sure the alarm
// is not missed.
//
// This means that an alarm can be delayed for up to 2 ticks (from t+1 to t+3), but this is allowed
// by the Alarm trait contract. What's not allowed is triggering alarms *before* their scheduled time,
// and we don't do that here.
let safe_timestamp = timestamp.max(t + 3);
let timer_ticks = (safe_timestamp - t) * *SCALE.get().unwrap();
alarm_tim.rst_value().write(|w| unsafe { w.bits(u32::MAX) });
if timer_ticks <= u32::MAX as u64 {
alarm_tim
.cnt_value()
.write(|w| unsafe { w.bits(timer_ticks as u32) });
alarm_tim.ctrl().modify(|_, w| w.irq_enb().set_bit());
alarm_tim.enable().write(|w| unsafe { w.bits(1) });
}
// If it's too far in the future, don't enable timer yet.
// It will be enabled later by `next_period`.
true
})
}
}
time_driver_impl!(
static DRIVER: TimerDriverEmbassy = TimerDriverEmbassy {
periods: AtomicU32::new(0),
alarm_count: AtomicU8::new(0),
alarms: Mutex::const_new(CriticalSectionRawMutex::new(), [AlarmState::new(); ALARM_COUNT])
});
#[interrupt]
#[allow(non_snake_case)]
fn TIM15() {
DRIVER.on_interrupt_timekeeping()
}
#[interrupt]
#[allow(non_snake_case)]
fn TIM14() {
DRIVER.on_interrupt_alarm(0)
}