forked from M-Labs/zynq-rs
libboard_zynq: impl embedded_hal CountDown for GlobalTimer
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4ab6fb6271
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8012573a8f
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@ -1,3 +1,4 @@
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use void::Void;
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use libregister::{RegisterR, RegisterW};
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use crate::{
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clocks::Clocks,
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@ -5,6 +6,7 @@ use crate::{
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time::Milliseconds,
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};
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/// "uptime"
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pub struct GlobalTimer {
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regs: &'static mut mpcore::RegisterBlock,
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}
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@ -14,7 +16,7 @@ impl GlobalTimer {
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let regs = mpcore::RegisterBlock::new();
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GlobalTimer { regs }
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}
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pub fn reset(&mut self) {
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// Disable
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self.regs.global_timer_control.write(
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@ -32,28 +34,64 @@ impl GlobalTimer {
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// Start
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self.regs.global_timer_control.write(
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mpcore::GlobalTimerControl::zeroed()
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// maximum prescaler is still enough for millisecond
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// precision while overflowing after centuries.
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.prescaler(255)
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.auto_increment_mode(true)
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.timer_enable(true)
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);
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}
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/// read the raw counter value
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pub fn get_counter(&self) -> u64 {
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loop {
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let c1 = self.regs.global_timer_counter1.read().value();
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let c1_pre = self.regs.global_timer_counter1.read().value();
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let c0 = self.regs.global_timer_counter0.read().value();
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let c1_post = self.regs.global_timer_counter1.read().value();
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if c1 == c1_post {
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return ((c1 as u64) << 32) | (c0 as u64);
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if c1_pre == c1_post {
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return ((c1_pre as u64) << 32) | (c0 as u64);
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}
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// retry if c0 has wrapped while reading.
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}
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}
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/// read and convert to time
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pub fn get_time(&self) -> Milliseconds {
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let prescaler = self.regs.global_timer_control.read().prescaler() as u64;
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let clocks = Clocks::get();
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Milliseconds(self.get_counter() * (prescaler + 1) / (clocks.cpu_3x2x() as u64 / 1000))
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}
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/// return a handle that has implements
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/// `embedded_hal::timer::CountDown`
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pub fn countdown(&self) -> CountDown {
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CountDown {
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timer: &self,
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timeout: Milliseconds(0),
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}
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}
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}
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#[derive(Clone)]
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pub struct CountDown<'a> {
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timer: &'a GlobalTimer,
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timeout: Milliseconds,
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}
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impl embedded_hal::timer::CountDown for CountDown<'_> {
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type Time = Milliseconds;
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fn start<T: Into<Self::Time>>(&mut self, count: T) {
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self.timeout = count.into();
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}
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fn wait(&mut self) -> nb::Result<(), Void> {
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if self.timer.get_time() < self.timeout {
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Err(nb::Error::WouldBlock)
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} else {
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Ok(())
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}
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}
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}
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@ -1,2 +1,2 @@
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mod global;
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pub mod global;
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pub use global::GlobalTimer;
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