1 files changed, 123 insertions, 1 deletions

diff --git a/src/peripheral/itm.rs b/src/peripheral/itm.rs
index c0d560f..24b926d 100644
--- a/src/peripheral/itm.rs
+++ b/src/peripheral/itm.rs
@@ -7,6 +7,9 @@ use core::ptr;
 
 use volatile_register::{RO, RW, WO};
 
+use crate::peripheral::ITM;
+use bitfield::bitfield;
+
 /// Register block
 #[repr(C)]
 pub struct RegisterBlock {
@@ -20,7 +23,7 @@ pub struct RegisterBlock {
     pub tpr: RW<u32>,
     reserved2: [u32; 15],
     /// Trace Control
-    pub tcr: RW<u32>,
+    pub tcr: RW<Tcr>,
     reserved3: [u32; 75],
     /// Lock Access
     pub lar: WO<u32>,
@@ -28,6 +31,22 @@ pub struct RegisterBlock {
     pub lsr: RO<u32>,
 }
 
+bitfield! {
+    /// Trace Control Register.
+    #[repr(C)]
+    #[derive(Copy, Clone)]
+    pub struct Tcr(u32);
+    get_itmena, set_itmena: 0;
+    get_tsena, set_tsena: 1;
+    get_syncena, set_synena: 2;
+    get_txena, set_txena: 3;
+    get_swoena, set_swoena: 4;
+    u8, get_tsprescale, set_tsprescale: 9, 8;
+    u8, get_gtsfreq, set_gtsfreq: 11, 10;
+    u8, get_tracebusid, set_tracebusid: 22, 16;
+    busy, _: 23;
+}
+
 /// Stimulus Port
 pub struct Stim {
     register: UnsafeCell<u32>,
@@ -69,3 +88,106 @@ impl Stim {
         unsafe { ptr::read_volatile(self.register.get()) & 0b11 != 0 }
     }
 }
+
+/// The possible local timestamp options.
+#[derive(Debug, PartialEq)]
+pub enum LocalTimestampOptions {
+    /// Disable local timestamps.
+    Disabled,
+    /// Enable local timestamps and use no prescaling.
+    Enabled,
+    /// Enable local timestamps and set the prescaler to divide the
+    /// reference clock by 4.
+    EnabledDiv4,
+    /// Enable local timestamps and set the prescaler to divide the
+    /// reference clock by 16.
+    EnabledDiv16,
+    /// Enable local timestamps and set the prescaler to divide the
+    /// reference clock by 64.
+    EnabledDiv64,
+}
+
+/// The possible global timestamp options.
+#[derive(Debug)]
+pub enum GlobalTimestampOptions {
+    /// Disable global timestamps.
+    Disabled,
+    /// Generate a global timestamp approximately every 128 cycles.
+    Every128Cycles,
+    /// Generate a global timestamp approximately every 8921 cycles.
+    Every8192Cycles,
+    /// Generate a global timestamp after every packet, if the output FIFO is empty.
+    EveryPacket,
+}
+
+/// The possible clock sources for timestamp counters.
+#[derive(Debug)]
+pub enum TimestampClkSrc {
+    /// Clock timestamp counters using the system processor clock.
+    SystemClock,
+    /// Clock timestamp counters using the asynchronous clock from the
+    /// TPIU interface.
+    ///
+    /// NOTE: The timestamp counter is held in reset while the output
+    /// line is idle.
+    AsyncTPIU,
+}
+
+/// blah
+#[derive(Debug)]
+pub struct ITMSettings {
+    /// Whether to enable ITM.
+    pub enable: bool,
+    /// Whether DWT packets should be forwarded to ITM.
+    pub forward_dwt: bool,
+    /// The local timestamp options that should be applied.
+    pub local_timestamps: LocalTimestampOptions,
+    /// The global timestamp options that should be applied.
+    pub global_timestamps: GlobalTimestampOptions,
+    /// The trace bus ID to use when multi-trace sources are in use.
+    /// `None` specifies that only a single trace source is in use and
+    /// has the same effect as `Some(0)`.
+    pub bus_id: Option<u8>,
+    /// The clock that should increase timestamp counters.
+    pub timestamp_clk_src: TimestampClkSrc,
+}
+
+impl ITM {
+    /// Removes the software lock on the ITM.
+    #[inline]
+    pub fn unlock(&mut self) {
+        // NOTE(unsafe) atomic write to a stateless, write-only register
+        unsafe { self.lar.write(0xC5AC_CE55) }
+    }
+
+    /// Configures the ITM with the passed [ITMSettings].
+    #[inline]
+    pub fn configure(&mut self, settings: ITMSettings) {
+        unsafe {
+            self.tcr.modify(|mut r| {
+                r.set_itmena(settings.enable);
+                r.set_tsena(settings.local_timestamps != LocalTimestampOptions::Disabled);
+                r.set_txena(settings.forward_dwt);
+                r.set_tsprescale(match settings.local_timestamps {
+                    LocalTimestampOptions::Disabled | LocalTimestampOptions::Enabled => 0b00,
+                    LocalTimestampOptions::EnabledDiv4 => 0b10,
+                    LocalTimestampOptions::EnabledDiv16 => 0b10,
+                    LocalTimestampOptions::EnabledDiv64 => 0b11,
+                });
+                r.set_gtsfreq(match settings.global_timestamps {
+                    GlobalTimestampOptions::Disabled => 0b00,
+                    GlobalTimestampOptions::Every128Cycles => 0b01,
+                    GlobalTimestampOptions::Every8192Cycles => 0b10,
+                    GlobalTimestampOptions::EveryPacket => 0b11,
+                });
+                r.set_swoena(match settings.timestamp_clk_src {
+                    TimestampClkSrc::SystemClock => false,
+                    TimestampClkSrc::AsyncTPIU => true,
+                });
+                r.set_tracebusid(settings.bus_id.unwrap_or(0));
+
+                r
+            });
+        }
+    }
+}