rtic_monotonics/imxrt.rs
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//! [`Monotonic`](rtic_time::Monotonic) implementations for i.MX RT's GPT peripherals.
//!
//! # Example
//!
//! ```
//! use rtic_monotonics::imxrt::prelude::*;
//! imxrt_gpt1_monotonic!(Mono, 1_000_000);
//!
//! fn init() {
//! // Obtain ownership of the timer register block.
//! let gpt1 = unsafe { imxrt_ral::gpt::GPT1::instance() };
//!
//! // Configure the timer tick rate as specified earlier
//! todo!("Configure the gpt1 peripheral to a tick rate of 1_000_000");
//!
//! // Start the monotonic
//! Mono::start(gpt1);
//! }
//!
//! async fn usage() {
//! loop {
//! // Use the monotonic
//! let timestamp = Mono::now();
//! Mono::delay(100.millis()).await;
//! }
//! }
//! ```
use portable_atomic::{AtomicU32, Ordering};
use rtic_time::{
half_period_counter::calculate_now,
timer_queue::{TimerQueue, TimerQueueBackend},
};
pub use imxrt_ral as ral;
/// Common definitions and traits for using the i.MX RT monotonics
pub mod prelude {
#[cfg(feature = "imxrt_gpt1")]
pub use crate::imxrt_gpt1_monotonic;
#[cfg(feature = "imxrt_gpt2")]
pub use crate::imxrt_gpt2_monotonic;
pub use crate::Monotonic;
pub use fugit::{self, ExtU64, ExtU64Ceil};
}
#[doc(hidden)]
#[macro_export]
macro_rules! __internal_create_imxrt_timer_interrupt {
($mono_backend:ident, $timer:ident) => {
#[no_mangle]
#[allow(non_snake_case)]
unsafe extern "C" fn $timer() {
use $crate::TimerQueueBackend;
$crate::imxrt::$mono_backend::timer_queue().on_monotonic_interrupt();
}
};
}
#[doc(hidden)]
#[macro_export]
macro_rules! __internal_create_imxrt_timer_struct {
($name:ident, $mono_backend:ident, $timer:ident, $tick_rate_hz:expr) => {
/// A `Monotonic` based on the GPT peripheral.
pub struct $name;
impl $name {
/// Starts the `Monotonic`.
///
/// This method must be called only once.
pub fn start(gpt: $crate::imxrt::ral::gpt::$timer) {
$crate::__internal_create_imxrt_timer_interrupt!($mono_backend, $timer);
$crate::imxrt::$mono_backend::_start(gpt);
}
}
impl $crate::TimerQueueBasedMonotonic for $name {
type Backend = $crate::imxrt::$mono_backend;
type Instant = $crate::fugit::Instant<
<Self::Backend as $crate::TimerQueueBackend>::Ticks,
1,
{ $tick_rate_hz },
>;
type Duration = $crate::fugit::Duration<
<Self::Backend as $crate::TimerQueueBackend>::Ticks,
1,
{ $tick_rate_hz },
>;
}
$crate::rtic_time::impl_embedded_hal_delay_fugit!($name);
$crate::rtic_time::impl_embedded_hal_async_delay_fugit!($name);
};
}
/// Create a GPT1 based monotonic and register the GPT1 interrupt for it.
///
/// See [`crate::imxrt`] for more details.
///
/// # Arguments
///
/// * `name` - The name that the monotonic type will have.
/// * `tick_rate_hz` - The tick rate of the timer peripheral. It's the user's responsibility
/// to configure the peripheral to the given frequency before starting the
/// monotonic.
#[cfg(feature = "imxrt_gpt1")]
#[macro_export]
macro_rules! imxrt_gpt1_monotonic {
($name:ident, $tick_rate_hz:expr) => {
$crate::__internal_create_imxrt_timer_struct!($name, Gpt1Backend, GPT1, $tick_rate_hz);
};
}
/// Create a GPT2 based monotonic and register the GPT2 interrupt for it.
///
/// See [`crate::imxrt`] for more details.
///
/// # Arguments
///
/// * `name` - The name that the monotonic type will have.
/// * `tick_rate_hz` - The tick rate of the timer peripheral. It's the user's responsibility
/// to configure the peripheral to the given frequency before starting the
/// monotonic.
#[cfg(feature = "imxrt_gpt2")]
#[macro_export]
macro_rules! imxrt_gpt2_monotonic {
($name:ident, $tick_rate_hz:expr) => {
$crate::__internal_create_imxrt_timer_struct!($name, Gpt2Backend, GPT2, $tick_rate_hz);
};
}
macro_rules! make_timer {
($mono_name:ident, $backend_name:ident, $timer:ident, $period:ident, $tq:ident$(, doc: ($($doc:tt)*))?) => {
/// GPT based [`TimerQueueBackend`].
$(
#[cfg_attr(docsrs, doc(cfg($($doc)*)))]
)?
pub struct $backend_name;
use ral::gpt::$timer;
/// Number of 2^31 periods elapsed since boot.
static $period: AtomicU32 = AtomicU32::new(0);
static $tq: TimerQueue<$backend_name> = TimerQueue::new();
impl $backend_name {
/// Starts the timer.
///
/// **Do not use this function directly.**
///
/// Use the prelude macros instead.
pub fn _start(gpt: $timer) {
// Disable the timer.
ral::modify_reg!(ral::gpt, gpt, CR, EN: 0);
// Clear all status registers.
ral::write_reg!(ral::gpt, gpt, SR, 0b11_1111);
// Base configuration
ral::modify_reg!(ral::gpt, gpt, CR,
ENMOD: 1, // Clear timer state
FRR: 1, // Free-Run mode
);
// Reset period
$period.store(0, Ordering::SeqCst);
// Enable interrupts
ral::write_reg!(ral::gpt, gpt, IR,
ROVIE: 1, // Rollover interrupt
OF1IE: 1, // Timer compare 1 interrupt (for half-periods)
OF2IE: 1, // Timer compare 2 interrupt (for dynamic wakeup)
);
// Configure half-period interrupt
ral::write_reg!(ral::gpt, gpt, OCR[0], 0x8000_0000);
// Dynamic interrupt register; for now initialize to zero
// so it gets combined with rollover interrupt
ral::write_reg!(ral::gpt, gpt, OCR[1], 0x0000_0000);
// Initialize timer queue
$tq.initialize(Self {});
// Enable the timer
ral::modify_reg!(ral::gpt, gpt, CR, EN: 1);
ral::modify_reg!(ral::gpt, gpt, CR,
ENMOD: 0, // Keep state when disabled
);
// SAFETY: We take full ownership of the peripheral and interrupt vector,
// plus we are not using any external shared resources so we won't impact
// basepri/source masking based critical sections.
unsafe {
crate::set_monotonic_prio(ral::NVIC_PRIO_BITS, ral::Interrupt::$timer);
cortex_m::peripheral::NVIC::unmask(ral::Interrupt::$timer);
}
}
}
impl TimerQueueBackend for $backend_name {
type Ticks = u64;
fn now() -> Self::Ticks {
let gpt = unsafe{ $timer::instance() };
calculate_now(
|| $period.load(Ordering::Relaxed),
|| ral::read_reg!(ral::gpt, gpt, CNT)
)
}
fn set_compare(instant: Self::Ticks) {
let gpt = unsafe{ $timer::instance() };
// Set the timer regardless of whether it is multiple periods in the future,
// or even already in the past.
// The worst thing that can happen is a spurious wakeup, and with a timer
// period of half an hour, this is hardly a problem.
let ticks_wrapped = instant as u32;
ral::write_reg!(ral::gpt, gpt, OCR[1], ticks_wrapped);
}
fn clear_compare_flag() {
let gpt = unsafe{ $timer::instance() };
ral::write_reg!(ral::gpt, gpt, SR, OF2: 1);
}
fn pend_interrupt() {
cortex_m::peripheral::NVIC::pend(ral::Interrupt::$timer);
}
fn on_interrupt() {
let gpt = unsafe{ $timer::instance() };
let (rollover, half_rollover) = ral::read_reg!(ral::gpt, gpt, SR, ROV, OF1);
if rollover != 0 {
let prev = $period.fetch_add(1, Ordering::Relaxed);
ral::write_reg!(ral::gpt, gpt, SR, ROV: 1);
assert!(prev % 2 == 1, "Monotonic must have skipped an interrupt!");
}
if half_rollover != 0 {
let prev = $period.fetch_add(1, Ordering::Relaxed);
ral::write_reg!(ral::gpt, gpt, SR, OF1: 1);
assert!(prev % 2 == 0, "Monotonic must have skipped an interrupt!");
}
}
fn timer_queue() -> &'static TimerQueue<Self> {
&$tq
}
}
};
}
#[cfg(feature = "imxrt_gpt1")]
make_timer!(Gpt1, Gpt1Backend, GPT1, GPT1_HALFPERIODS, GPT1_TQ);
#[cfg(feature = "imxrt_gpt2")]
make_timer!(Gpt2, Gpt2Backend, GPT2, GPT2_HALFPERIODS, GPT2_TQ);