Use bare_metal::CriticalSection for GPIO configuration

Author: urdh

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 
 - Updated the `cast` dependency from 0.2 to 0.3
+- Use `bare_metal::CriticalSection` for GPIO configuration (breaking change)
 
 ### Added
 

examples/serial_spi_bridge.rs

@@ -36,7 +36,11 @@ fn main() -> ! {
 
         let gpioa = p.GPIOA.split(&mut rcc);
 
-        let (sck, miso, mosi, tx, rx) = cortex_m::interrupt::free(move |cs| {
+        let (sck, miso, mosi, tx, rx) = cortex_m::interrupt::free(move |_| {
+            // SAFETY: We are in a critical section, but the `cortex_m` critical section
+            // token is not compatible with the `bare_metal` token. Future version of the
+            // `cortex_m` crate will not supply *any* token to this callback!
+            let cs = unsafe { &bare_metal::CriticalSection::new() };
             (
                 // SPI pins
                 gpioa.pa5.into_alternate_af0(cs),

examples/spi_hal_apa102c.rs

@@ -28,7 +28,11 @@ fn main() -> ! {
         let gpioa = p.GPIOA.split(&mut rcc);
 
         // Configure pins for SPI
-        let (sck, miso, mosi) = cortex_m::interrupt::free(move |cs| {
+        let (sck, miso, mosi) = cortex_m::interrupt::free(move |_| {
+            // SAFETY: We are in a critical section, but the `cortex_m` critical section
+            // token is not compatible with the `bare_metal` token. Future version of the
+            // `cortex_m` crate will not supply *any* token to this callback!
+            let cs = unsafe { &bare_metal::CriticalSection::new() };
             (
                 gpioa.pa5.into_alternate_af0(cs),
                 gpioa.pa6.into_alternate_af0(cs),

src/gpio.rs

@@ -190,7 +190,7 @@ macro_rules! gpio {
                     pac::$GPIOX
                 };
 
-                use cortex_m::interrupt::CriticalSection;
+                use bare_metal::CriticalSection;
 
                 use super::{
                     Alternate, Analog, Floating, GpioExt, Input, OpenDrain, Output,