zynq-rs/libboard_zynq/src/timer/global.rs

120 lines
3.2 KiB
Rust
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use void::Void;
use libregister::{RegisterR, RegisterW};
use crate::{
clocks::Clocks,
mpcore,
time::Milliseconds,
};
/// "uptime"
#[derive(Clone, Copy)]
pub struct GlobalTimer {
regs: &'static mpcore::RegisterBlock,
}
impl GlobalTimer {
/// Get the potentially uninitialized timer
pub unsafe fn get() -> GlobalTimer {
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let regs = mpcore::RegisterBlock::new();
GlobalTimer { regs }
}
/// Get the timer with a reset
pub fn start() -> GlobalTimer {
let mut regs = mpcore::RegisterBlock::new();
Self::reset(&mut regs);
GlobalTimer { regs }
}
fn reset(regs: &mut mpcore::RegisterBlock) {
// Disable
regs.global_timer_control.write(
mpcore::GlobalTimerControl::zeroed()
);
// Reset counters
regs.global_timer_counter0.write(
mpcore::ValueRegister::zeroed()
);
regs.global_timer_counter1.write(
mpcore::ValueRegister::zeroed()
);
// find a prescaler value that matches CPU speed / 2 to us
let clocks = Clocks::get();
let mut prescaler = clocks.cpu_3x2x() / 1_000_000;
while prescaler > 256 {
prescaler /= 2;
}
// Start
regs.global_timer_control.write(
mpcore::GlobalTimerControl::zeroed()
.prescaler((prescaler - 1) as u8)
.auto_increment_mode(true)
.timer_enable(true)
);
}
/// read the raw counter value
pub fn get_counter(&self) -> u64 {
loop {
let c1_pre = self.regs.global_timer_counter1.read().value();
let c0 = self.regs.global_timer_counter0.read().value();
let c1_post = self.regs.global_timer_counter1.read().value();
if c1_pre == c1_post {
return ((c1_pre as u64) << 32) | (c0 as u64);
}
// retry if c0 has wrapped while reading.
}
}
/// read and convert to time
pub fn get_time(&self) -> Milliseconds {
let prescaler = self.regs.global_timer_control.read().prescaler() as u64;
let clocks = Clocks::get();
Milliseconds(self.get_counter() * (prescaler + 1) / (clocks.cpu_3x2x() as u64 / 1000))
}
/// read with high precision
pub fn get_us(&self) -> u64 {
let prescaler = self.regs.global_timer_control.read().prescaler() as u64;
let clocks = Clocks::get();
1_000_000 * self.get_counter() * (prescaler + 1) / clocks.cpu_3x2x() as u64
}
/// return a handle that has implements
/// `embedded_hal::timer::CountDown`
pub fn countdown(&self) -> CountDown {
CountDown {
timer: self.clone(),
timeout: Milliseconds(0),
}
}
}
#[derive(Clone)]
pub struct CountDown {
timer: GlobalTimer,
timeout: Milliseconds,
}
impl embedded_hal::timer::CountDown for CountDown {
type Time = Milliseconds;
fn start<T: Into<Self::Time>>(&mut self, count: T) {
self.timeout = self.timer.get_time() + count.into();
}
fn wait(&mut self) -> nb::Result<(), Void> {
if self.timer.get_time() <= self.timeout {
Err(nb::Error::WouldBlock)
} else {
Ok(())
}
}
}