From e12a1ba142094ea31b6e404bdabcf45f2d6421ae Mon Sep 17 00:00:00 2001
From: Codetector <codetector@codetector.org>
Date: Sun, 3 Nov 2024 00:15:45 -0700
Subject: [PATCH] bugfix(broken atomic): Remove all uses of atomic

This change remvoes all use of atomic (CAS) from ch32-hal

As discovered in #59, the QingKeV4 atomic implementation is likely
broken. As a result we added a compiler check to make sure the atomic
exetnsion is disabled in ch32-rs/qingke#8. This change updates the
dependency to use the new qingke as well as remove any reference to
`core::atomic` in ch32-hal.
---
 src/dma/dma_bdma.rs                | 24 +++++++++++-------------
 src/embassy/time_driver_systick.rs | 19 +++++++++----------
 2 files changed, 20 insertions(+), 23 deletions(-)

diff --git a/src/dma/dma_bdma.rs b/src/dma/dma_bdma.rs
index 2ec7aaf..b27c595 100644
--- a/src/dma/dma_bdma.rs
+++ b/src/dma/dma_bdma.rs
@@ -1,8 +1,10 @@
+use core::cell::Cell;
 use core::future::{poll_fn, Future};
 use core::pin::Pin;
 use core::sync::atomic::{compiler_fence, fence, AtomicUsize, Ordering};
 use core::task::{Context, Poll, Waker};
 
+use embassy_sync::blocking_mutex::CriticalSectionMutex;
 use embassy_sync::waitqueue::AtomicWaker;
 
 use super::ringbuffer::{DmaCtrl, OverrunError, ReadableDmaRingBuffer, WritableDmaRingBuffer};
@@ -144,13 +146,12 @@ impl AnyChannel {
                 } else if isr.tcif(info.num) && cr.read().tcie() {
                     // Acknowledge transfer complete interrupt
                     r.ifcr().write(|w| w.set_tcif(info.num, true));
-                    #[cfg(not(qingke_v2))]
-                    state.complete_count.fetch_add(1, Ordering::Release);
-                    #[cfg(qingke_v2)]
                     critical_section::with(|_| {
-                        let x = state.complete_count.load(Ordering::Relaxed);
-                        state.complete_count.store(x + 1, Ordering::Release);
-                    })
+                        // #safty this is okay because critical section ensures
+                        // no interruption
+                        let cnt = state.complete_count.load(Ordering::Acquire);
+                        state.complete_count.store(cnt + 1, Ordering::Release);
+                    });
                 } else {
                     return;
                 }
@@ -476,14 +477,11 @@ impl<'a> DmaCtrl for DmaCtrlImpl<'a> {
 
     fn reset_complete_count(&mut self) -> usize {
         let state = &STATE[self.0.id as usize];
-        #[cfg(not(qingke_v2))]
-        return state.complete_count.swap(0, Ordering::AcqRel);
-        #[cfg(qingke_v2)]
-        return critical_section::with(|_| {
-            let x = state.complete_count.load(Ordering::Acquire);
+        critical_section::with(|_| {
+            let old_val = state.complete_count.load(Ordering::Acquire);
             state.complete_count.store(0, Ordering::Release);
-            x
-        });
+            old_val
+        })
     }
 
     fn set_waker(&mut self, waker: &Waker) {
diff --git a/src/embassy/time_driver_systick.rs b/src/embassy/time_driver_systick.rs
index f28d076..9028ebc 100644
--- a/src/embassy/time_driver_systick.rs
+++ b/src/embassy/time_driver_systick.rs
@@ -1,6 +1,5 @@
 //! SysTick-based time driver.
 
-use core::arch::asm;
 use core::cell::Cell;
 use core::sync::atomic::{AtomicU32, AtomicU8, Ordering};
 use core::{mem, ptr};
@@ -9,11 +8,9 @@ use critical_section::{CriticalSection, Mutex};
 use embassy_time_driver::{AlarmHandle, Driver};
 use pac::systick::vals;
 use qingke::interrupt::Priority;
-#[cfg(feature = "highcode")]
-use qingke_rt::highcode;
 use qingke_rt::interrupt;
 
-use crate::{pac, println};
+use crate::pac;
 
 pub const ALARM_COUNT: usize = 1;
 
@@ -130,20 +127,21 @@ impl Driver for SystickDriver {
         let period = self.period.load(Ordering::Relaxed) as u64;
         rb.cnt().read() / period
     }
+
     unsafe fn allocate_alarm(&self) -> Option<AlarmHandle> {
-        let id = self.alarm_count.fetch_update(Ordering::AcqRel, Ordering::Acquire, |x| {
+        let id = critical_section::with(|_| {
+            let x = self.alarm_count.load(Ordering::Acquire);
             if x < ALARM_COUNT as u8 {
-                Some(x + 1)
+                self.alarm_count.store(x + 1, Ordering::Release);
+                Some(x)
             } else {
                 None
             }
         });
 
-        match id {
-            Ok(id) => Some(AlarmHandle::new(id)),
-            Err(_) => None,
-        }
+        id.map(|id| AlarmHandle::new(id))
     }
+
     fn set_alarm_callback(&self, alarm: AlarmHandle, callback: fn(*mut ()), ctx: *mut ()) {
         critical_section::with(|cs| {
             let alarm = self.get_alarm(cs, alarm);
@@ -152,6 +150,7 @@ impl Driver for SystickDriver {
             alarm.ctx.set(ctx);
         })
     }
+
     fn set_alarm(&self, alarm: AlarmHandle, timestamp: u64) -> bool {
         critical_section::with(|cs| {
             let rb = &crate::pac::SYSTICK;