Introduce Rust FSBL

examples/simple/src/main.rs

@@ -4,24 +4,33 @@
 
 use core::panic::PanicInfo;
 use cortex_ar::asm::nop;
-use embedded_hal::digital::StatefulOutputPin;
+use embedded_hal::{delay::DelayNs, digital::StatefulOutputPin};
 use zynq7000::PsPeripherals;
 use zynq7000_hal::{
-    gpio::{Output, PinState, mio},
+    clocks::Clocks,
+    gpio::{mio, Output, PinState},
     l2_cache,
+    priv_tim::CpuPrivateTimer,
+    time::Hertz,
 };
 use zynq7000_rt as _;
 
+pub const LIB: Lib = Lib::Hal;
+
 /// One user LED is MIO7
 const ZEDBOARD_LED_MASK: u32 = 1 << 7;
 
+// Define the clock frequency as a constant.
+//
+// Not required for the PAC mode, is required for clean delays in HAL mode.
+const PS_CLOCK_FREQUENCY: Hertz = Hertz::from_raw(33_333_333);
+
 #[derive(Debug)]
 pub enum Lib {
     Pac,
     Hal,
 }
 
-const LIB: Lib = Lib::Hal;
 
 /// Entry point (not called like a normal main function)
 #[unsafe(no_mangle)]
@@ -49,13 +58,14 @@ pub fn main() -> ! {
         }
         Lib::Hal => {
             let dp = PsPeripherals::take().unwrap();
+            let clocks = Clocks::new_from_regs(PS_CLOCK_FREQUENCY).unwrap();
+            // Unwrap okay, we only call this once on core 0 here.
+            let mut cpu_tim = CpuPrivateTimer::take(clocks.arm_clocks()).unwrap();
             let mio_pins = mio::Pins::new(dp.gpio);
             let mut led = Output::new_for_mio(mio_pins.mio7, PinState::High);
             loop {
                 led.toggle().unwrap();
-                for _ in 0..5_000_000 {
-                    nop();
-                }
+                cpu_tim.delay_ms(1000);
             }
         }
     }
@@ -64,22 +74,22 @@ pub fn main() -> ! {
 #[zynq7000_rt::irq]
 pub fn irq_handler() {}
 
-#[unsafe(no_mangle)]
-pub extern "C" fn _abort_handler() {
+#[zynq7000_rt::exception(DataAbort)]
+fn data_abort_handler(_faulting_addr: usize) -> ! {
     loop {
         nop();
     }
 }
 
-#[unsafe(no_mangle)]
-pub extern "C" fn _undefined_handler() {
+#[zynq7000_rt::exception(Undefined)]
+fn undefined_handler(_faulting_addr: usize) -> ! {
     loop {
         nop();
     }
 }
 
-#[unsafe(no_mangle)]
-pub extern "C" fn _prefetch_handler() {
+#[zynq7000_rt::exception(PrefetchAbort)]
+fn prefetch_handler(_faulting_addr: usize) -> ! {
     loop {
         nop();
     }