Add time management

src/bsp/aarch64/mod.rs

@@ -0,0 +1,3 @@
+//! Modules specific to the aarch64 architecture.
+
+pub mod time;

src/bsp/aarch64/time.rs

@@ -0,0 +1,88 @@
+//! The implementation of the time management trait for aarch64.
+
+use core::arch::asm;
+use core::time::Duration;
+
+use crate::traits::time::TimeManager;
+use crate::println;
+
+const NS_PER_S: u64 = 1_000_000_000;
+const CNTP_CTL_EL0_ENABLE_MASK: u64 = 0b001;
+const CNTP_CTL_EL0_IMASK_MASK: u64 = 0b010;
+const CNTP_CTL_EL0_ISTATUS_MASK: u64 = 0b100;
+
+/// AARCH64 Timer.
+struct Timer;
+
+/// The global timer.
+static TIME_MANAGER: Timer = Timer;
+
+/// Return a reference to the global time manager.
+pub fn time_manager() -> &'static impl TimeManager {
+    &TIME_MANAGER
+}
+
+impl TimeManager for Timer {
+    fn frequency(&self) -> u64 {
+        let freq: u64;
+        unsafe {
+            asm!("mrs {0:x}, CNTFRQ_EL0", out(reg) freq, options(nomem, nostack));
+        }
+        freq
+    }
+
+    fn uptime(&self) -> Duration {
+        let ticks: u64;
+        unsafe {
+            // Protect against out of order execution
+            // https://developer.arm.com/documentation/dui0802/b/CIHGHHIE
+            // In effect this flush the processor pipeline
+            asm!("ISB", options(nostack));
+            asm!("mrs {0:x}, CNTPCT_EL0", out(reg) ticks, options(nomem, nostack));
+        }
+        Duration::from_nanos((ticks*NS_PER_S)/self.frequency())
+    }
+
+    fn sleep(&self, duration: Duration) {
+        if duration.as_nanos() == 0 {
+            return;
+        }
+
+        let tmp = match self.frequency().checked_mul(duration.as_nanos() as u64) {
+            None => {
+                println!("Cannot sleep this long, skipping");
+                return;
+            }
+            Some(tmp) => tmp,
+        };
+        let ticks = tmp / NS_PER_S;
+
+        if ticks > u32::max_value().into() {
+            println!("Cannot wait more than 2^32-1 ticks on aarch64, skipping");
+            return;
+        }
+        if ticks == 0 {
+            println!("Duration is smaller than a clock tick, skipping.");
+            return;
+        }
+
+        // Enable the timer and mask (disable) the interrupt 
+        let mut ctl: u64 = CNTP_CTL_EL0_ENABLE_MASK + CNTP_CTL_EL0_IMASK_MASK;
+        unsafe {
+            // set the register values for the timer
+            asm!("msr CNTP_TVAL_EL0, {0:x}", in(reg) ticks, options(nomem, nostack));
+            asm!("msr CNTP_CTL_EL0, {0:x}", in(reg) ctl, options(nomem, nostack));
+        }
+        // Loop waiting for the timer to run out
+        while (ctl & CNTP_CTL_EL0_ISTATUS_MASK) == 0 {
+            unsafe {
+                asm!("mrs {0:x}, CNTP_CTL_EL0", out(reg) ctl, options(nomem, nostack));
+            }
+        }
+        // Disable the counter
+        ctl &= !CNTP_CTL_EL0_ENABLE_MASK;
+        unsafe {
+            asm!("msr CNTP_CTL_EL0, {0:x}", in(reg) ctl, options(nomem, nostack));
+        }
+    }
+}

src/bsp/mod.rs

@@ -6,3 +6,6 @@ pub mod rpi3;
 
 #[cfg(feature = "target_rpi4")]
 pub mod rpi4;
+
+#[cfg(target_arch = "aarch64")]
+pub mod aarch64;

src/main.rs

@@ -26,11 +26,17 @@ use core::arch::global_asm;
 #[cfg(not(test))]
 use core::arch::asm;
 
+use core::time::Duration;
+
 // TODO: handle this with features
 #[cfg(not(test))]
 use crate::bsp::rpi3::uart::console;
 #[cfg(not(test))]
 use crate::bsp::rpi3::gpio;
+#[cfg(not(test))]
+use crate::bsp::aarch64::time::time_manager;
+
+use crate::traits::time::TimeManager;
 
 // TODO: move this to BSP
 /// Pause the core with a infinit loop
@@ -93,20 +99,18 @@ pub unsafe fn _start_rust() -> ! {
         Err(err) => println!("Failled to set pin: {err}"),
     }
     loop {
+        let uptime = time_manager().uptime();
         match gpio::set_pin_output_state(21, gpio::PinOutputState::High) {
-            Ok(()) => (),
+            Ok(()) => println!("[{:>6}.{:06}] OUTPUT 21 UP", uptime.as_secs(), uptime.subsec_micros()),
             Err(_err) => println!("Failled to set pin 21 to High"),
         }
-        for _ in 0..5000000 {
+        time_manager().sleep(Duration::from_secs(1));
-            asm!("nop");
+        let uptime = time_manager().uptime();
-        }
         match gpio::set_pin_output_state(21, gpio::PinOutputState::Low) {
-            Ok(()) => (),
+            Ok(()) => println!("[{:>6}.{:06}] OUTPUT 21 DOWN", uptime.as_secs(), uptime.subsec_micros()),
             Err(_err) => println!("Failled to set pin 21 to Low"),
         }
-        for _ in 0..5000000 {
+        time_manager().sleep(Duration::from_secs(1));
-            asm!("nop");
-        }
     }
     /*
     println!("Hello there");

src/traits/mod.rs

@@ -10,3 +10,4 @@
 
 pub mod console;
 pub mod synchronization;
+pub mod time;

src/traits/time.rs

@@ -0,0 +1,16 @@
+//! Traits for time management primitives.
+
+use core::time::Duration;
+
+pub trait TimeManager {
+
+    /// Return the clock frequency, meaning the resolution of the 
+    /// time mesurement.
+    fn frequency(&self) -> u64;
+
+    /// The uptime since last power-on.
+    fn uptime(&self) -> Duration;
+
+    /// Sleep for the duration.
+    fn sleep(&self, duration: Duration);
+}