setup: use a best-effort lock for rprintln

close #382
This commit is contained in:
Robert Jördens 2021-06-24 08:11:46 +00:00
parent c935f97752
commit a3dd760aba
1 changed files with 35 additions and 7 deletions

View File

@ -1,6 +1,8 @@
///! Stabilizer hardware configuration
///!
///! This file contains all of the hardware-specific configuration of Stabilizer.
use core::sync::atomic::{self, AtomicBool, Ordering};
use core::{ptr, slice};
use stm32h7xx_hal::{
self as hal,
ethernet::{self, PHY},
@ -149,8 +151,6 @@ fn load_itcm() {
static mut __eitcm: u32;
static mut __siitcm: u32;
}
use core::{ptr, slice, sync::atomic};
// NOTE(unsafe): Assuming the address symbols from the linker as well as
// the source instruction data are all valid, this is safe as it only
// copies linker-prepared data to where the code expects it to be.
@ -163,7 +163,7 @@ fn load_itcm() {
ptr::write_volatile(ITCMCR, ptr::read_volatile(ITCMCR) | 1);
// Ensure ITCM is enabled before loading.
atomic::fence(atomic::Ordering::SeqCst);
atomic::fence(Ordering::SeqCst);
let len =
(&__eitcm as *const u32).offset_from(&__sitcm as *const _) as usize;
@ -174,7 +174,7 @@ fn load_itcm() {
}
// Ensure ITCM is loaded before potentially executing any instructions from it.
atomic::fence(atomic::Ordering::SeqCst);
atomic::fence(Ordering::SeqCst);
cortex_m::asm::dsb();
cortex_m::asm::isb();
}
@ -224,10 +224,38 @@ pub fn setup(
// Enable debug during WFE/WFI-induced sleep
device.DBGMCU.cr.modify(|_, w| w.dbgsleep_d1().set_bit());
use rtt_logger::RTTLogger;
// Set up RTT channel to use for `rprintln!()` as "best effort".
// This removes a critical section around the logging and thus allows
// high-prio tasks to always interrupt at low latency.
// It comes at a cost:
// If a high-priority tasks preempts while we are logging something,
// and if we then also want to log from within that high-preiority task,
// the high-prio log message will be lost.
static LOGGER: RTTLogger = RTTLogger::new(log::LevelFilter::Info);
rtt_target::rtt_init_print!();
let channels = rtt_target::rtt_init_default!();
// Note(unsafe): The closure we pass does not establish a critical section
// as demanded but it ensure synchronization and implements a lock.
unsafe {
rtt_target::set_print_channel_cs(
channels.up.0,
&((|arg, f| {
static LOGGER_LOCK: AtomicBool = AtomicBool::new(false);
if LOGGER_LOCK.compare_exchange_weak(
false,
true,
Ordering::Acquire,
Ordering::Relaxed,
) == Ok(false)
{
f(arg);
LOGGER_LOCK.store(false, Ordering::Release);
}
}) as rtt_target::CriticalSectionFunc),
);
}
static LOGGER: rtt_logger::RTTLogger =
rtt_logger::RTTLogger::new(log::LevelFilter::Info);
log::set_logger(&LOGGER)
.map(|()| log::set_max_level(log::LevelFilter::Trace))
.unwrap();