Removed use of static mut.

nrf52-code/boards/dk-solution/Cargo.toml

@@ -12,6 +12,7 @@ cortex-m-semihosting = "0.5.0"
 defmt = "0.3.5"
 defmt-rtt = "0.4"
 embedded-hal = "0.2.7"
+grounded = { version = "0.2.0", features = ["cas"] }
 hal = { package = "nrf52840-hal", version = "0.16.0" }
 
 [features]

nrf52-code/boards/dk-solution/src/lib.rs

@@ -15,7 +15,11 @@ use core::{
 use cortex_m::peripheral::NVIC;
 use cortex_m_semihosting::debug;
 use embedded_hal::digital::v2::{InputPin, OutputPin, StatefulOutputPin};
-#[cfg(feature = "radio")]
+#[cfg(any(feature = "advanced"))]
+use grounded::uninit::GroundedArrayCell;
+#[cfg(any(feature = "radio"))]
+use grounded::uninit::GroundedCell;
+#[cfg(any(feature = "radio"))]
 pub use hal::ieee802154;
 pub use hal::pac::{interrupt, Interrupt, NVIC_PRIO_BITS, RTC0};
 use hal::{
@@ -40,6 +44,14 @@ pub mod peripheral;
 #[cfg(feature = "advanced")]
 pub mod usbd;
 
+#[cfg(feature = "radio")]
+struct ClockSyncWrapper<H, L, LSTAT> {
+    clocks: Clocks<H, L, LSTAT>,
+}
+
+#[cfg(feature = "radio")]
+unsafe impl<H, L, LSTAT> Sync for ClockSyncWrapper<H, L, LSTAT> {}
+
 /// Components on the board
 pub struct Board {
     /// LEDs
@@ -210,6 +222,7 @@ impl ops::DerefMut for Timer {
 }
 
 /// The ways that initialisation can fail
+#[derive(Debug, Copy, Clone, defmt::Format)]
 pub enum Error {
     /// You tried to initialise the board twice
     DoubleInit = 1,
@@ -224,12 +237,16 @@ pub fn init() -> Result<Board, Error> {
     };
     // NOTE(static mut) this branch runs at most once
     #[cfg(feature = "advanced")]
-    static mut EP0IN_BUF: [u8; 64] = [0; 64];
+    static EP0IN_BUF: GroundedArrayCell<u8, 64> = GroundedArrayCell::const_init();
     #[cfg(feature = "radio")]
-    static mut CLOCKS: Option<
-        Clocks<clocks::ExternalOscillator, clocks::ExternalOscillator, clocks::LfOscStarted>,
-    > = None;
-
+    // We need the wrapper to make this type Sync, as it contains raw pointers
+    static CLOCKS: GroundedCell<
+        ClockSyncWrapper<
+            clocks::ExternalOscillator,
+            clocks::ExternalOscillator,
+            clocks::LfOscStarted,
+        >,
+    > = GroundedCell::uninit();
     defmt::debug!("Initializing the board");
 
     let clocks = Clocks::new(periph.CLOCK);
@@ -239,7 +256,14 @@ pub fn init() -> Result<Board, Error> {
     let _clocks = clocks.enable_ext_hfosc();
     // extend lifetime to `'static`
     #[cfg(feature = "radio")]
-    let clocks = unsafe { CLOCKS.get_or_insert(_clocks) };
+    let clocks = unsafe {
+        let clocks_ptr = CLOCKS.get();
+        clocks_ptr.write(ClockSyncWrapper { clocks: _clocks });
+        // Now it's initialised, we can take a static reference to the clocks
+        // object it contains.
+        let clock_wrapper: &'static ClockSyncWrapper<_, _, _> = &*clocks_ptr;
+        &clock_wrapper.clocks
+    };
 
     defmt::debug!("Clocks configured");
 
@@ -311,7 +335,7 @@ pub fn init() -> Result<Board, Error> {
         #[cfg(feature = "advanced")]
         power: periph.POWER,
         #[cfg(feature = "advanced")]
-        ep0in: unsafe { Ep0In::new(&mut EP0IN_BUF) },
+        ep0in: unsafe { Ep0In::new(&EP0IN_BUF) },
     })
 }
 

nrf52-code/boards/dk-solution/src/usbd.rs

@@ -2,21 +2,23 @@
 
 use core::sync::atomic::{self, Ordering};
 
+use grounded::uninit::GroundedArrayCell;
+
 use crate::{
     errata,
     peripheral::{POWER, USBD},
 };
 
 /// Endpoint IN 0
 pub struct Ep0In {
-    buffer: &'static mut [u8; 64],
+    buffer: &'static GroundedArrayCell<u8, 64>,
     busy: bool,
 }
 
 impl Ep0In {
     /// # Safety
     /// Must be created at most once (singleton)
-    pub(crate) unsafe fn new(buffer: &'static mut [u8; 64]) -> Self {
+    pub(crate) unsafe fn new(buffer: &'static GroundedArrayCell<u8, 64>) -> Self {
         Self {
             buffer,
             busy: false,
@@ -30,14 +32,17 @@ impl Ep0In {
     /// - This function panics if the last transfer was not finished by calling the `end` function
     /// - This function panics if `bytes` is larger than the maximum packet size (64 bytes)
     pub fn start(&mut self, bytes: &[u8], usbd: &USBD) {
+        let (buffer_ptr, buffer_len) = self.buffer.get_ptr_len();
         assert!(!self.busy, "EP0IN: last transfer has not completed");
         assert!(
-            bytes.len() <= self.buffer.len(),
+            bytes.len() <= buffer_len,
             "EP0IN: multi-packet data transfers are not supported"
         );
 
         let n = bytes.len();
-        self.buffer[..n].copy_from_slice(bytes);
+        unsafe {
+            core::ptr::copy_nonoverlapping(bytes.as_ptr(), buffer_ptr, n);
+        }
 
         // use a "shortcut" to issue a status stage after the data transfer is complete
         usbd.shorts
@@ -47,7 +52,7 @@ impl Ep0In {
             .write(|w| unsafe { w.maxcnt().bits(n as u8) });
         usbd.epin0
             .ptr
-            .write(|w| unsafe { w.ptr().bits(self.buffer.as_ptr() as u32) });
+            .write(|w| unsafe { w.ptr().bits(buffer_ptr as u32) });
 
         self.busy = true;
 

nrf52-code/boards/dk/Cargo.toml

@@ -12,6 +12,7 @@ cortex-m-semihosting = "0.5.0"
 defmt = "0.3.5"
 defmt-rtt = "0.4"
 embedded-hal = "0.2.7"
+grounded = { version = "0.2.0", features = ["cas"] }
 hal = { package = "nrf52840-hal", version = "0.16.0" }
 
 [features]

nrf52-code/boards/dk/src/lib.rs

@@ -15,7 +15,11 @@ use core::{
 use cortex_m::peripheral::NVIC;
 use cortex_m_semihosting::debug;
 use embedded_hal::digital::v2::{OutputPin, StatefulOutputPin};
-#[cfg(feature = "radio")]
+#[cfg(any(feature = "advanced"))]
+use grounded::uninit::GroundedArrayCell;
+#[cfg(any(feature = "radio"))]
+use grounded::uninit::GroundedCell;
+#[cfg(any(feature = "radio"))]
 pub use hal::ieee802154;
 pub use hal::pac::{interrupt, Interrupt, NVIC_PRIO_BITS, RTC0};
 use hal::{
@@ -40,6 +44,14 @@ pub mod peripheral;
 #[cfg(feature = "advanced")]
 pub mod usbd;
 
+#[cfg(feature = "radio")]
+struct ClockSyncWrapper<H, L, LSTAT> {
+    clocks: Clocks<H, L, LSTAT>,
+}
+
+#[cfg(feature = "radio")]
+unsafe impl<H, L, LSTAT> Sync for ClockSyncWrapper<H, L, LSTAT> {}
+
 /// Components on the board
 pub struct Board {
     /// LEDs
@@ -199,12 +211,16 @@ pub fn init() -> Result<Board, Error> {
     };
     // NOTE(static mut) this branch runs at most once
     #[cfg(feature = "advanced")]
-    static mut EP0IN_BUF: [u8; 64] = [0; 64];
+    static EP0IN_BUF: GroundedArrayCell<u8, 64> = GroundedArrayCell::const_init();
     #[cfg(feature = "radio")]
-    static mut CLOCKS: Option<
-        Clocks<clocks::ExternalOscillator, clocks::ExternalOscillator, clocks::LfOscStarted>,
-    > = None;
-
+    // We need the wrapper to make this type Sync, as it contains raw pointers
+    static CLOCKS: GroundedCell<
+        ClockSyncWrapper<
+            clocks::ExternalOscillator,
+            clocks::ExternalOscillator,
+            clocks::LfOscStarted,
+        >,
+    > = GroundedCell::uninit();
     defmt::debug!("Initializing the board");
 
     let clocks = Clocks::new(periph.CLOCK);
@@ -214,7 +230,14 @@ pub fn init() -> Result<Board, Error> {
     let _clocks = clocks.enable_ext_hfosc();
     // extend lifetime to `'static`
     #[cfg(feature = "radio")]
-    let clocks = unsafe { CLOCKS.get_or_insert(_clocks) };
+    let clocks = unsafe {
+        let clocks_ptr = CLOCKS.get();
+        clocks_ptr.write(ClockSyncWrapper { clocks: _clocks });
+        // Now it's initialised, we can take a static reference to the clocks
+        // object it contains.
+        let clock_wrapper: &'static ClockSyncWrapper<_, _, _> = &*clocks_ptr;
+        &clock_wrapper.clocks
+    };
 
     defmt::debug!("Clocks configured");
 
@@ -274,7 +297,7 @@ pub fn init() -> Result<Board, Error> {
         #[cfg(feature = "advanced")]
         power: periph.POWER,
         #[cfg(feature = "advanced")]
-        ep0in: unsafe { Ep0In::new(&mut EP0IN_BUF) },
+        ep0in: unsafe { Ep0In::new(&EP0IN_BUF) },
     })
 }
 

nrf52-code/boards/dk/src/usbd.rs

@@ -2,21 +2,23 @@
 
 use core::sync::atomic::{self, Ordering};
 
+use grounded::uninit::GroundedArrayCell;
+
 use crate::{
     errata,
     peripheral::{POWER, USBD},
 };
 
 /// Endpoint IN 0
 pub struct Ep0In {
-    buffer: &'static mut [u8; 64],
+    buffer: &'static GroundedArrayCell<u8, 64>,
     busy: bool,
 }
 
 impl Ep0In {
     /// # Safety
     /// Must be created at most once (singleton)
-    pub(crate) unsafe fn new(buffer: &'static mut [u8; 64]) -> Self {
+    pub(crate) unsafe fn new(buffer: &'static GroundedArrayCell<u8, 64>) -> Self {
         Self {
             buffer,
             busy: false,
@@ -30,14 +32,17 @@ impl Ep0In {
     /// - This function panics if the last transfer was not finished by calling the `end` function
     /// - This function panics if `bytes` is larger than the maximum packet size (64 bytes)
     pub fn start(&mut self, bytes: &[u8], usbd: &USBD) {
+        let (buffer_ptr, buffer_len) = self.buffer.get_ptr_len();
         assert!(!self.busy, "EP0IN: last transfer has not completed");
         assert!(
-            bytes.len() <= self.buffer.len(),
+            bytes.len() <= buffer_len,
             "EP0IN: multi-packet data transfers are not supported"
         );
 
         let n = bytes.len();
-        self.buffer[..n].copy_from_slice(bytes);
+        unsafe {
+            core::ptr::copy_nonoverlapping(bytes.as_ptr(), buffer_ptr, n);
+        }
 
         // use a "shortcut" to issue a status stage after the data transfer is complete
         usbd.shorts
@@ -47,7 +52,7 @@ impl Ep0In {
             .write(|w| unsafe { w.maxcnt().bits(n as u8) });
         usbd.epin0
             .ptr
-            .write(|w| unsafe { w.ptr().bits(self.buffer.as_ptr() as u32) });
+            .write(|w| unsafe { w.ptr().bits(buffer_ptr as u32) });
 
         self.busy = true;