Add method of passing peripherals from init_array to main

Signed-off-by: Gabriel Smith <[email protected]>

Cargo.toml

@@ -10,7 +10,7 @@ repository = "https://github.com/japaric/cortex-m-rt"
 version = "0.3.13"
 
 [dependencies]
-cortex-m = "0.3.0"
+cortex-m = "0.4.3"
 r0 = "0.2.1"
 
 [features]

build.rs

@@ -24,6 +24,7 @@ fn main() {
 
     has_fpu(&target);
     is_armv6m(&target);
+    is_armv7m(&target);
 
     // Put the linker script somewhere the linker can find it
     let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
@@ -48,3 +49,12 @@ fn is_armv6m(target: &str) {
         println!("cargo:rustc-cfg=armv6m");
     }
 }
+
+fn is_armv7m(target: &str) {
+    if target.starts_with("thumbv7m-") {
+        println!("cargo:rustc-cfg=armv7m");
+    } else if target.starts_with("thumbv7em-") {
+        println!("cargo:rustc-cfg=armv7m");
+        //println!("cargo:rustc-cfg=armv7em");
+    }
+}

src/init_array.rs

@@ -0,0 +1,186 @@
+//! Core peripheral support when using `init_array`
+//!
+//! Allows passing on any subset of peripherals normally `take`n from
+//! `cortex_m::peripheral::Peripherals`. Once in `main` `InitArrayPeripherals`
+//! cannot be given back.
+//!
+//! ``` no_run
+//! extern crate cortex_m;
+//!
+//! use cortex_m_rt::init_array::InitArrayPeripherals;
+//!
+//! init_array!(before_main, {
+//!     let mut peripherals = InitArrayPeripherals::take().unwrap();
+//!     peripherals.DWT.enable_cycle_counter();
+//!     InitArrayPeripherals::give(peripherals);
+//! });
+//!
+//! fn main() {
+//!     let ok = InitArrayPeripherals::take().unwrap();
+//!     let panics = InitArrayPeripherals::take().unwrap();
+//! }
+//! ```
+//!
+//! Select peripherals can be dropped by creating a new `InitArrayPeripherals`
+//! with `None` in place of the peripheral.
+//!
+//! ``` no_run
+//! extern crate cortex_m;
+//!
+//! use cortex_m::peripheral::Peripherals;
+//! use cortex_m_rt::init_array::InitArrayPeripherals;
+//!
+//! init_array!(before_main, {
+//!     let mut Peripherals {
+//!         CBP,
+//!         CPUID,
+//!         DCB,
+//!         DWT,
+//!         FPB,
+//!         FPU,
+//!         ITM,
+//!         MPU,
+//!         NVIC,
+//!         SCB,
+//!         SYST,
+//!         TPIU,
+//!     } = Peripherals::take().unwrap();
+//!     DWT.enable_cycle_counter();
+//!     let pass_on_peripherals = InitArrayPeripherals {
+//!         Some(CBP),
+//!         Some(CPUID),
+//!         Some(DCB),
+//!         None,       // Don't pass on DWT
+//!         Some(FPB),
+//!         Some(FPU),
+//!         Some(ITM),
+//!         Some(MPU),
+//!         Some(NVIC),
+//!         Some(SCB),
+//!         Some(SYST),
+//!         Some(TPIU),
+//!     }
+//!     InitArrayPeripherals::give(pass_on_peripherals);
+//! });
+//!
+//! fn main() {
+//!     let peripherals = InitArrayPeripherals::take().unwrap();
+//!     assert!(peripherals.DWT.is_none());
+//! }
+//! ```
+
+#![allow(private_no_mangle_statics)]
+
+use cortex_m::peripheral::{self, Peripherals};
+use cortex_m::interrupt;
+
+/// Core peripherals handed back from `init_array`
+#[allow(non_snake_case)]
+pub struct InitArrayPeripherals {
+    /// Cache and branch predictor maintenance operations
+    #[cfg(any(armv7m, target_arch = "x86_64"))]
+    pub CBP: Option<peripheral::CBP>,
+    /// CPUID
+    pub CPUID: Option<peripheral::CPUID>,
+    /// Debug Control Block
+    pub DCB: Option<peripheral::DCB>,
+    /// Data Watchpoint and Trace unit
+    pub DWT: Option<peripheral::DWT>,
+    /// Flash Patch and Breakpoint unit
+    #[cfg(any(armv7m, target_arch = "x86_64"))]
+    pub FPB: Option<peripheral::FPB>,
+    /// Floating Point Unit
+    #[cfg(any(has_fpu, target_arch = "x86_64"))]
+    pub FPU: Option<peripheral::FPU>,
+    /// Instrumentation Trace Macrocell
+    #[cfg(any(armv7m, target_arch = "x86_64"))]
+    pub ITM: Option<peripheral::ITM>,
+    /// Memory Protection Unit
+    pub MPU: Option<peripheral::MPU>,
+    /// Nested Vector Interrupt Controller
+    pub NVIC: Option<peripheral::NVIC>,
+    /// System Control Block
+    pub SCB: Option<peripheral::SCB>,
+    /// SysTick: System Timer
+    pub SYST: Option<peripheral::SYST>,
+    /// Trace Port Interface Unit;
+    #[cfg(any(armv7m, target_arch = "x86_64"))]
+    pub TPIU: Option<peripheral::TPIU>,
+}
+
+#[no_mangle]
+static mut INIT_ARRAY_PERIPHERALS: Option<InitArrayPeripherals> = None;
+#[no_mangle]
+static mut INIT_ARRAY_DONE: bool = false;
+
+impl InitArrayPeripherals {
+    /// Returns all the core peripherals. Can be given back in an `init_array`
+    /// function by calling `give`.
+    pub fn take() -> Option<Self> {
+        interrupt::free(|_| { unsafe { INIT_ARRAY_PERIPHERALS.take() } }).or_else(|| {
+            Peripherals::take().map(InitArrayPeripherals::from)
+        })
+    }
+
+    /// Give the peripherals back for use in `main` after using them in
+    /// `init_array`. Does nothing if called after `init_array`.
+    pub fn give<P: Into<InitArrayPeripherals>>(p: P) {
+        interrupt::free(|_| {
+            if unsafe { !INIT_ARRAY_DONE } {
+                unsafe { INIT_ARRAY_PERIPHERALS = Some(p.into()) }
+            }
+        })
+    }
+
+    pub(crate) fn done() {
+        interrupt::free(|_| {
+            unsafe { INIT_ARRAY_DONE = true };
+        })
+    }
+}
+
+#[allow(non_snake_case)]
+impl From<Peripherals> for InitArrayPeripherals {
+    fn from(p: Peripherals) -> Self {
+        let Peripherals {
+            #[cfg(any(armv7m, target_arch = "x86_64"))]
+            CBP,
+            CPUID,
+            DCB,
+            DWT,
+            #[cfg(any(armv7m, target_arch = "x86_64"))]
+            FPB,
+            #[cfg(any(has_fpu, target_arch = "x86_64"))]
+            FPU,
+            #[cfg(any(armv7m, target_arch = "x86_64"))]
+            ITM,
+            MPU,
+            NVIC,
+            SCB,
+            SYST,
+            #[cfg(any(armv7m, target_arch = "x86_64"))]
+            TPIU,
+            ..
+        } = p;
+
+        InitArrayPeripherals {
+            #[cfg(any(armv7m, target_arch = "x86_64"))]
+            CBP: Some(CBP),
+            CPUID: Some(CPUID),
+            DCB: Some(DCB),
+            DWT: Some(DWT),
+            #[cfg(any(armv7m, target_arch = "x86_64"))]
+            FPB: Some(FPB),
+            #[cfg(any(has_fpu, target_arch = "x86_64"))]
+            FPU: Some(FPU),
+            #[cfg(any(armv7m, target_arch = "x86_64"))]
+            ITM: Some(ITM),
+            MPU: Some(MPU),
+            NVIC: Some(NVIC),
+            SCB: Some(SCB),
+            SYST: Some(SYST),
+            #[cfg(any(armv7m, target_arch = "x86_64"))]
+            TPIU: Some(TPIU),
+        }
+    }
+}

src/lib.rs

@@ -502,6 +502,8 @@ extern crate r0;
 
 #[cfg(all(feature = "init_array", target_arch = "arm"))]
 pub use r0::init_array;
+#[cfg(all(feature = "init_array", target_arch = "arm"))]
+pub mod init_array;
 
 #[cfg(not(test))]
 mod lang_items;
@@ -547,6 +549,8 @@ static RESET_VECTOR: unsafe extern "C" fn() -> ! = reset_handler;
 unsafe extern "C" fn reset_handler() -> ! {
     #[cfg(feature = "init_array")]
     r0::run_init_array(&_init_array_start, &_init_array_end);
+    #[cfg(feature = "init_array")]
+    init_array::InitArrayPeripherals::done();
     r0::zero_bss(&mut _sbss, &mut _ebss);
     r0::init_data(&mut _sdata, &mut _edata, &_sidata);