Import panic-itm

1 files changed, 58 insertions, 0 deletions

diff --git a/panic-itm/src/lib.rs b/panic-itm/src/lib.rs
new file mode 100644
index 0000000..eedc38c
--- /dev/null
+++ b/panic-itm/src/lib.rs
@@ -0,0 +1,58 @@
+//! Log panic messages using the ITM (Instrumentation Trace Macrocell)
+//!
+//! This crate contains an implementation of `panic_fmt` that logs panic messages to the ITM
+//! stimulus port 0. Before printing the message the panic handler disables (masks) all the device
+//! specific interrupts. After printing the message the panic handler goes into an infinite loop.
+//!
+//! # Usage
+//!
+//! ``` ignore
+//! #![no_std]
+//!
+//! extern crate panic_itm;
+//!
+//! fn main() {
+//!     panic!("FOO")
+//! }
+//! ```
+//!
+//! ``` text
+//! (gdb) monitor tpiu config external uart off 8000000 2000000
+//! (gdb) monitor itm port 0 on
+//! (gdb) continue
+//! (..)
+//! ```
+//!
+//! ``` text
+//! $ itmdump -f /dev/ttyUSB0
+//! panicked at 'FOO', src/main.rs:6:5
+//! ```
+
+#![deny(missing_docs)]
+#![deny(warnings)]
+#![no_std]
+
+extern crate cortex_m;
+
+use core::panic::PanicInfo;
+use core::sync::atomic::{self, Ordering};
+
+use cortex_m::interrupt;
+use cortex_m::iprintln;
+use cortex_m::peripheral::ITM;
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    interrupt::disable();
+
+    let itm = unsafe { &mut *ITM::ptr() };
+    let stim = &mut itm.stim[0];
+
+    iprintln!(stim, "{}", info);
+
+    loop {
+        // add some side effect to prevent this from turning into a UDF instruction
+        // see rust-lang/rust#28728 for details
+        atomic::compiler_fence(Ordering::SeqCst);
+    }
+}