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switch to crate arm_pl031 to read the realtime clock #1694

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switch to crate arm_pl031 to read the realtime clock #1694

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10 changes: 10 additions & 0 deletions Cargo.lock
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1 change: 1 addition & 0 deletions Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -171,6 +171,7 @@ memory_addresses = { version = "0.2.2", default-features = false, features = [
[target.'cfg(target_arch = "aarch64")'.dependencies]
aarch64 = { version = "0.0.13", default-features = false }
arm-gic = { version = "0.3" }
arm_pl031 = {version = "0.2.1" }
hermit-dtb = { version = "0.1" }
semihosting = { version = "0.1", optional = true }
memory_addresses = { version = "0.2.2", default-features = false, features = [
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47 changes: 12 additions & 35 deletions src/arch/aarch64/kernel/systemtime.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@ use alloc::vec::Vec;
use core::arch::asm;
use core::str;

use arm_pl031::Rtc;
use hermit_dtb::Dtb;
use hermit_sync::OnceCell;
use memory_addresses::arch::aarch64::{PhysAddr, VirtAddr};
Expand All @@ -13,38 +14,9 @@ use crate::arch::aarch64::mm::paging::{self, BasePageSize, PageSize, PageTableEn
use crate::env;
use crate::mm::virtualmem;

static PL031_ADDRESS: OnceCell<VirtAddr> = OnceCell::new();
static RTC_PL031: OnceCell<Rtc> = OnceCell::new();
static BOOT_TIME: OnceCell<u64> = OnceCell::new();

const RTC_DR: usize = 0x00;
const RTC_MR: usize = 0x04;
const RTC_LR: usize = 0x08;
const RTC_CR: usize = 0x0c;
/// Interrupt mask and set register
const RTC_IRQ_MASK: usize = 0x10;
/// Raw interrupt status
const RTC_RAW_IRQ_STATUS: usize = 0x14;
/// Masked interrupt status
const RTC_MASK_IRQ_STATUS: usize = 0x18;
/// Interrupt clear register
const RTC_IRQ_CLEAR: usize = 0x1c;

#[inline]
fn rtc_read(off: usize) -> u32 {
let value: u32;

// we have to use inline assembly to guarantee 32bit memory access
unsafe {
asm!("ldar {value:w}, [{addr}]",
value = out(reg) value,
addr = in(reg) (PL031_ADDRESS.get().unwrap().as_usize() + off),
options(nostack, readonly),
);
}

value
}

pub fn init() {
let dtb = unsafe {
Dtb::from_raw(core::ptr::with_exposed_provenance(
Expand All @@ -71,8 +43,6 @@ pub fn init() {
BasePageSize::SIZE.try_into().unwrap(),
)
.unwrap();
PL031_ADDRESS.set(pl031_address).unwrap();
debug!("Mapping RTC to virtual address {pl031_address:p}",);

let mut flags = PageTableEntryFlags::empty();
flags.device().writable().execute_disable();
Expand All @@ -83,20 +53,27 @@ pub fn init() {
flags,
);

debug!("Mapping RTC to virtual address {pl031_address:p}");

let rtc = unsafe { Rtc::new(pl031_address.as_mut_ptr()) };
let boot_time =
OffsetDateTime::from_unix_timestamp(rtc_read(RTC_DR).into()).unwrap();
OffsetDateTime::from_unix_timestamp(rtc.get_unix_timestamp().into()).unwrap();
info!("Hermit booted on {boot_time}");

let micros = u64::try_from(boot_time.unix_timestamp_nanos() / 1000).unwrap();
let current_ticks = super::processor::get_timer_ticks();
BOOT_TIME.set(micros - current_ticks).unwrap();

assert!(
BOOT_TIME.set(micros - current_ticks).is_err(),
"Unable to set BOOT_TIME"
);
assert!(RTC_PL031.set(rtc).is_err(), "Unable to set RTC_PL031");

return;
}
}
}

PL031_ADDRESS.set(VirtAddr::zero()).unwrap();
BOOT_TIME.set(0).unwrap();
}

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