Merge #294

294: use the safe DWT::unlock API r=korken89 a=japaric

instead of a unsafe write_volatile call

Co-authored-by: Jorge Aparicio <jorge@japaric.io>

2 files changed, 5 insertions, 3 deletions

diff --git a/Cargo.toml b/Cargo.toml
index ce371f93..01b3ede3 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -47,7 +47,7 @@ name = "types"
 required-features = ["__v7"]
 
 [dependencies]
-cortex-m = "0.6.0"
+cortex-m = "0.6.2"
 cortex-m-rtfm-macros = { path = "macros", version = "0.5.0" }
 rtfm-core = "0.3.0"
 cortex-m-rt = "0.6.9"
diff --git a/examples/schedule.rs b/examples/schedule.rs
index a1c41ca5..d5de9dbf 100644
--- a/examples/schedule.rs
+++ b/examples/schedule.rs
@@ -1,9 +1,11 @@
 //! examples/schedule.rs
 
+#![deny(unsafe_code)]
 #![deny(warnings)]
 #![no_main]
 #![no_std]
 
+use cortex_m::peripheral::DWT;
 use cortex_m_semihosting::hprintln;
 use panic_halt as _;
 use rtfm::cyccnt::{Instant, U32Ext as _};
@@ -15,8 +17,8 @@ const APP: () = {
     fn init(mut cx: init::Context) {
         // Initialize (enable) the monotonic timer (CYCCNT)
         cx.core.DCB.enable_trace();
-        // required on devices that software lock the DWT (e.g. STM32F7)
-        unsafe { cx.core.DWT.lar.write(0xC5ACCE55) }
+        // required on Cortex-M7 devices that software lock the DWT (e.g. STM32F7)
+        DWT::unlock();
         cx.core.DWT.enable_cycle_counter();
 
         // semantically, the monotonic timer is frozen at time "zero" during `init`