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fix: 🐛 Read actual timer frequency

This commit is contained in:
Berkus Decker 2023-07-30 00:08:53 +03:00 committed by Berkus Decker
parent 0f435d7152
commit fc01f03714
1 changed files with 8 additions and 11 deletions
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19
machine/src/arch/aarch64/time.rs
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@ -12,13 +12,14 @@
//! crate::time::arch_time //! crate::time::arch_time
use { use {
crate::warn, crate::{sync, warn},
aarch64_cpu::{asm::barrier, registers::*}, aarch64_cpu::{asm::barrier, registers::*},
core::{ core::{
num::{NonZeroU128, NonZeroU32, NonZeroU64}, num::{NonZeroU128, NonZeroU32, NonZeroU64},
ops::{Add, Div}, ops::{Add, Div},
time::Duration, time::Duration,
}, },
once_cell::unsync::Lazy,
tock_registers::interfaces::Readable, tock_registers::interfaces::Readable,
}; };
@ -35,22 +36,18 @@ struct GenericTimerCounterValue(u64);
// Global instances // Global instances
//-------------------------------------------------------------------------------------------------- //--------------------------------------------------------------------------------------------------
/// Boot assembly code overwrites this value with the value of CNTFRQ_EL0 before any Rust code is static ARCH_TIMER_COUNTER_FREQUENCY: sync::NullLock<Lazy<NonZeroU32>> =
/// executed. This given value here is just a (safe) dummy. sync::NullLock::new(Lazy::new(|| {
#[no_mangle] NonZeroU32::try_from(CNTFRQ_EL0.get() as u32).unwrap()
static ARCH_TIMER_COUNTER_FREQUENCY: NonZeroU32 = NonZeroU32::MIN; }));
//-------------------------------------------------------------------------------------------------- //--------------------------------------------------------------------------------------------------
// Private Code // Private Code
//-------------------------------------------------------------------------------------------------- //--------------------------------------------------------------------------------------------------
fn arch_timer_counter_frequency() -> NonZeroU32 { fn arch_timer_counter_frequency() -> NonZeroU32 {
// Read volatile is needed here to prevent the compiler from optimizing use crate::sync::interface::Mutex;
// ARCH_TIMER_COUNTER_FREQUENCY away. ARCH_TIMER_COUNTER_FREQUENCY.lock(|inner| **inner)
//
// This is safe, because all the safety requirements as stated in read_volatile()'s
// documentation are fulfilled.
unsafe { core::ptr::read_volatile(&ARCH_TIMER_COUNTER_FREQUENCY) }
} }
impl GenericTimerCounterValue { impl GenericTimerCounterValue {