libboard_zynq: add GlobalTimer::get_us(), use in libsupport_zynq::logger

experiments/src/main.rs

@@ -268,7 +268,11 @@ pub fn main_core0() {
     task::spawn(async move {
         loop {
             delay(&mut countdown, Milliseconds(1000)).await;
-            println!("time: {} ms", timer.get_time().0);
+
+            let timestamp = timer.get_us();
+            let seconds   = timestamp / 1_000_000;
+            let micros    = timestamp % 1_000_000;
+            println!("time: {:6}.{:06}s", seconds, micros);
         }
     });
 

libboard_zynq/src/timer/global.rs

@@ -78,6 +78,14 @@ impl GlobalTimer {
         Milliseconds(self.get_counter() * (prescaler + 1) / (clocks.cpu_3x2x() as u64 / 1000))
     }
 
+    /// read with high precision
+    pub fn get_us(&self) -> u64 {
+        let prescaler = self.regs.global_timer_control.read().prescaler() as u64;
+        let clocks = Clocks::get();
+
+        1_000_000 * self.get_counter() * (prescaler + 1) / clocks.cpu_3x2x() as u64
+    }
+
     /// return a handle that has implements
     /// `embedded_hal::timer::CountDown`
     pub fn countdown(&self) -> CountDown {

libsupport_zynq/src/logger.rs

@@ -1,6 +1,6 @@
 //! A logger for the `log` crate
 
-use libboard_zynq::{println, stdio};
+use libboard_zynq::{println, stdio, timer::GlobalTimer};
 
 pub static LOGGER: Logger = Logger;
 
@@ -17,8 +17,9 @@ impl log::Log for Logger {
 
     fn log(&self, record: &log::Record) {
         if self.enabled(record.metadata()) {
-            // TODO: let timestamp = clock::get_us();
-            let timestamp = 0;
+            let timestamp = unsafe {
+                GlobalTimer::get()
+            }.get_us();
             let seconds   = timestamp / 1_000_000;
             let micros    = timestamp % 1_000_000;