1 files changed, 169 insertions, 0 deletions

diff --git a/src/clkout.rs b/src/clkout.rs
new file mode 100644
index 000000000..88c731df1
--- /dev/null
+++ b/src/clkout.rs
@@ -0,0 +1,169 @@
+//! CLKOUT pseudo-peripheral
+//!
+//! CLKOUT is a part of the clock generation subsystem, and can be used
+//! either to generate arbitrary waveforms, or to debug the state of
+//! internal oscillators.
+
+use core::marker::PhantomData;
+
+use embassy_hal_internal::Peri;
+
+pub use crate::clocks::periph_helpers::Div4;
+use crate::clocks::{with_clocks, ClockError, PoweredClock};
+use crate::pac::mrcc0::mrcc_clkout_clksel::Mux;
+use crate::peripherals::CLKOUT;
+
+/// A peripheral representing the CLKOUT pseudo-peripheral
+pub struct ClockOut<'a> {
+    _p: PhantomData<&'a mut CLKOUT>,
+    freq: u32,
+}
+
+/// Selected clock source to output
+pub enum ClockOutSel {
+    /// 12MHz Internal Oscillator
+    Fro12M,
+    /// FRO180M Internal Oscillator, via divisor
+    FroHfDiv,
+    /// External Oscillator
+    ClkIn,
+    /// 16KHz oscillator
+    Clk16K,
+    /// Output of PLL1
+    Pll1Clk,
+    /// Main System CPU clock, divided by 6
+    SlowClk,
+}
+
+/// Configuration for the ClockOut
+pub struct Config {
+    /// Selected Source Clock
+    pub sel: ClockOutSel,
+    /// Selected division level
+    pub div: Div4,
+    /// Selected power level
+    pub level: PoweredClock,
+}
+
+impl<'a> ClockOut<'a> {
+    /// Create a new ClockOut pin. On success, the clock signal will begin immediately
+    /// on the given pin.
+    pub fn new(
+        _peri: Peri<'a, CLKOUT>,
+        pin: Peri<'a, impl sealed::ClockOutPin>,
+        cfg: Config,
+    ) -> Result<Self, ClockError> {
+        // There's no MRCC enable bit, so we check the validity of the clocks here
+        //
+        // TODO: Should we check that the frequency is suitably low?
+        let (freq, mux) = check_sel(cfg.sel, cfg.level)?;
+
+        // All good! Apply requested config, starting with the pin.
+        pin.mux();
+
+        setup_clkout(mux, cfg.div);
+
+        Ok(Self {
+            _p: PhantomData,
+            freq: freq / cfg.div.into_divisor(),
+        })
+    }
+
+    /// Frequency of the clkout pin
+    #[inline]
+    pub fn frequency(&self) -> u32 {
+        self.freq
+    }
+}
+
+impl Drop for ClockOut<'_> {
+    fn drop(&mut self) {
+        disable_clkout();
+    }
+}
+
+/// Check whether the given clock selection is valid
+fn check_sel(sel: ClockOutSel, level: PoweredClock) -> Result<(u32, Mux), ClockError> {
+    let res = with_clocks(|c| {
+        Ok(match sel {
+            ClockOutSel::Fro12M => (c.ensure_fro_hf_active(&level)?, Mux::Clkroot12m),
+            ClockOutSel::FroHfDiv => (c.ensure_fro_hf_div_active(&level)?, Mux::ClkrootFircDiv),
+            ClockOutSel::ClkIn => (c.ensure_clk_in_active(&level)?, Mux::ClkrootSosc),
+            ClockOutSel::Clk16K => (c.ensure_clk_16k_vdd_core_active(&level)?, Mux::Clkroot16k),
+            ClockOutSel::Pll1Clk => (c.ensure_pll1_clk_active(&level)?, Mux::ClkrootSpll),
+            ClockOutSel::SlowClk => (c.ensure_slow_clk_active(&level)?, Mux::ClkrootSlow),
+        })
+    });
+    let Some(res) = res else {
+        return Err(ClockError::NeverInitialized);
+    };
+    res
+}
+
+/// Set up the clkout pin using the given mux and div settings
+fn setup_clkout(mux: Mux, div: Div4) {
+    let mrcc = unsafe { crate::pac::Mrcc0::steal() };
+
+    mrcc.mrcc_clkout_clksel().write(|w| w.mux().variant(mux));
+
+    // Set up clkdiv
+    mrcc.mrcc_clkout_clkdiv().write(|w| {
+        w.halt().set_bit();
+        w.reset().set_bit();
+        unsafe { w.div().bits(div.into_bits()) };
+        w
+    });
+    mrcc.mrcc_clkout_clkdiv().write(|w| {
+        w.halt().clear_bit();
+        w.reset().clear_bit();
+        unsafe { w.div().bits(div.into_bits()) };
+        w
+    });
+
+    while mrcc.mrcc_clkout_clkdiv().read().unstab().bit_is_set() {}
+}
+
+/// Stop the clkout
+fn disable_clkout() {
+    // Stop the output by selecting the "none" clock
+    //
+    // TODO: restore the pin to hi-z or something?
+    let mrcc = unsafe { crate::pac::Mrcc0::steal() };
+    mrcc.mrcc_clkout_clkdiv().write(|w| {
+        w.reset().set_bit();
+        w.halt().set_bit();
+        unsafe {
+            w.div().bits(0);
+        }
+        w
+    });
+    mrcc.mrcc_clkout_clksel().write(|w| unsafe { w.bits(0b111) });
+}
+
+mod sealed {
+    use embassy_hal_internal::PeripheralType;
+
+    use crate::gpio::{Pull, SealedPin};
+
+    /// Sealed marker trait for clockout pins
+    pub trait ClockOutPin: PeripheralType {
+        /// Set the given pin to the correct muxing state
+        fn mux(&self);
+    }
+
+    macro_rules! impl_pin {
+        ($pin:ident, $func:ident) => {
+            impl ClockOutPin for crate::peripherals::$pin {
+                fn mux(&self) {
+                    self.set_function(crate::pac::port0::pcr0::Mux::$func);
+                    self.set_pull(Pull::Disabled);
+                }
+            }
+        };
+    }
+
+    impl_pin!(P0_6, Mux12);
+    impl_pin!(P3_6, Mux1);
+    impl_pin!(P3_8, Mux12);
+    impl_pin!(P4_2, Mux1);
+}