5 files changed, 414 insertions, 0 deletions
diff --git a/src/dotstar.rs b/src/dotstar.rs
new file mode 100644
index 0000000..8e930d0
--- /dev/null
+++ b/src/dotstar.rs
@@ -0,0 +1,42 @@
+use trinket_m0::{
+    clock::GenericClockController,
+    gpio::{self, Floating, Input},
+    prelude::*,
+    sercom::{self, PadPin, SPIMaster1},
+    PM, SERCOM1,
+};
+
+use apa102_spi::Apa102;
+
+pub fn new(
+    sercom: SERCOM1,
+    miso: gpio::Pa31<Input<Floating>>,
+    mosi: gpio::Pa0<Input<Floating>>,
+    sck: gpio::Pa1<Input<Floating>>,
+    port: &mut gpio::Port,
+    pm: &mut PM,
+    clocks: &mut GenericClockController,
+) -> Apa102<
+    SPIMaster1<
+        sercom::Sercom1Pad3<gpio::Pa31<gpio::PfD>>,
+        sercom::Sercom1Pad0<gpio::Pa0<gpio::PfD>>,
+        sercom::Sercom1Pad1<gpio::Pa1<gpio::PfD>>,
+    >,
+> {
+    let gclk = clocks.gclk0();
+    let miso = miso.into_pad(port);
+    let mosi = mosi.into_pad(port);
+    let sck = sck.into_pad(port);
+    let spi = SPIMaster1::new(
+        &clocks
+            .sercom1_core(&gclk)
+            .expect("setting up sercom1 clock"),
+        3.mhz(),
+        apa102_spi::MODE,
+        sercom,
+        pm,
+        (miso, mosi, sck),
+    );
+
+    Apa102::new(spi)
+}
diff --git a/src/logger.rs b/src/logger.rs
new file mode 100644
index 0000000..be9d391
--- /dev/null
+++ b/src/logger.rs
@@ -0,0 +1,139 @@
+use crate::rtc;
+use starb::{Reader, RingBuffer, Writer};
+
+use core::cell::UnsafeCell;
+use core::fmt::{self, Write};
+use embedded_hal::{digital::v2::OutputPin, serial};
+use log::{Metadata, Record};
+use trinket_m0::{
+    gpio::{Pa6, Pa7, PfD},
+    sercom::{Sercom0Pad2, Sercom0Pad3, UART0},
+};
+
+static mut UART0: usize = 0;
+
+struct JoinedRingBuffer<'a> {
+    lbr: Reader<'a, u8>,
+    lbw: Writer<'a, u8>,
+}
+
+impl<'a> JoinedRingBuffer<'a> {
+    const fn new(rb: &'a RingBuffer<u8>) -> Self {
+        let (lbr, lbw) = rb.split();
+        Self { lbr: lbr, lbw: lbw }
+    }
+}
+
+impl fmt::Write for JoinedRingBuffer<'_> {
+    fn write_str(&mut self, s: &str) -> Result<(), fmt::Error> {
+        for b in s.bytes() {
+            if let Err(_) = self.lbw.unshift(b) {
+                // Ignore buffer full errors for logging.
+                return Ok(());
+            }
+        }
+        Ok(())
+    }
+}
+
+static mut LB: RingBuffer<u8> = RingBuffer::<u8>::new(0);
+static mut JRB: JoinedRingBuffer = unsafe { JoinedRingBuffer::new(&LB) };
+
+// The UART isn't necessarily Sync, so wrap it in something that
+// is. As long as flush() is only called from one thread, we're fine,
+// but this is a guarantee that the logger module doesn't make.
+pub struct WriteWrapper<W> {
+    w: W,
+}
+impl<W> WriteWrapper<W>
+where
+    W: serial::Write<u8>,
+{
+    pub fn new(writer: W) -> Self {
+        Self { w: writer }
+    }
+}
+unsafe impl<W> Sync for WriteWrapper<W> {}
+
+pub struct SerialLogger<W, L> {
+    writer: UnsafeCell<WriteWrapper<W>>,
+    led: UnsafeCell<L>,
+}
+
+impl<W, L> SerialLogger<W, L>
+where
+    W: serial::Write<u8>,
+    L: OutputPin + Send + Sync,
+{
+    pub fn new(writer: WriteWrapper<W>, led: L) -> Self {
+        // Stash this for unsafe usage in case there's an issue with
+        // the rest of the logging.
+        unsafe { UART0 = core::mem::transmute(&writer.w) };
+        Self {
+            writer: UnsafeCell::new(writer),
+            led: UnsafeCell::new(led),
+        }
+    }
+}
+unsafe impl<W, L> Send for SerialLogger<W, L> {}
+unsafe impl<W, L> Sync for SerialLogger<W, L> {}
+
+impl<W, L> log::Log for SerialLogger<W, L>
+where
+    W: serial::Write<u8>,
+    L: OutputPin + Send + Sync,
+{
+    fn enabled(&self, metadata: &Metadata) -> bool {
+        metadata.level() <= log::max_level()
+    }
+
+    fn log(&self, record: &Record) {
+        if !self.enabled(record.metadata()) {
+            return;
+        }
+
+        let jrb = unsafe { &mut JRB };
+        write!(
+            jrb,
+            "[{}] {} {} -- {}\r\n",
+            rtc::millis(),
+            record.level(),
+            record.target(),
+            record.args()
+        )
+        .ok();
+    }
+
+    fn flush(&self) {
+        // Unsafe due to mutable static. We can only deal with the
+        // tail position of the buffer here to keep things safe.
+        let jrb = unsafe { &mut JRB };
+        if jrb.lbr.is_empty() {
+            return;
+        }
+
+        let led = unsafe { &mut (*self.led.get()) };
+        let writer = unsafe { &mut (*self.writer.get()) };
+
+        led.set_high().ok();
+        while let Some(b) = jrb.lbr.shift() {
+            nb::block!(writer.w.write(b)).ok();
+        }
+        led.set_low().ok();
+    }
+}
+
+// Write to the UART right now, instead of putting it on a ring
+// buffer. This function is a huge hack, and only useful for debugging
+// either before the main loop starts or if the ring buffer is broken.
+pub unsafe fn write_fmt_now(args: fmt::Arguments, nl: bool) {
+    if UART0 == 0 {
+        return;
+    }
+    let uart: &mut UART0<Sercom0Pad3<Pa7<PfD>>, Sercom0Pad2<Pa6<PfD>>, (), ()> =
+        core::mem::transmute(UART0);
+    fmt::write(uart, args).expect("writing fmt now to uart");
+    if nl {
+        uart.write_str("\r\n").expect("writing nl now to uart");
+    }
+}
diff --git a/src/macros.rs b/src/macros.rs
new file mode 100644
index 0000000..46d2d07
--- /dev/null
+++ b/src/macros.rs
@@ -0,0 +1,15 @@
+#[macro_export]
+macro_rules! logln_now {
+    ($($arg:tt)*) => {
+        unsafe {crate::logger::write_fmt_now(format_args!($($arg)*), true);}
+    };
+    (_) => {};
+}
+
+#[macro_export]
+macro_rules! log_now {
+    ($($arg:tt)*) => {
+        unsafe {crate::logger::write_fmt_now(format_args!($($arg)*), false);}
+    };
+    (_) => {};
+}
diff --git a/src/main.rs b/src/main.rs
new file mode 100755
index 0000000..071966a
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,144 @@
+#![no_std]
+#![no_main]
+
+mod dotstar;
+mod logger;
+mod macros;
+mod rtc;
+
+use clint::HandlerArray;
+use core::mem;
+use core::panic::PanicInfo;
+use cortex_m::asm::wfi;
+use cortex_m_rt::{entry, exception, ExceptionFrame};
+use embedded_hal::digital::v2::OutputPin;
+use log::{info, LevelFilter};
+use smart_leds::colors;
+use smart_leds_trait::SmartLedsWrite;
+use trinket_m0::{
+    self as hal,
+    clock::GenericClockController,
+    gpio::{OpenDrain, Output, Pa10, Pa6, Pa7, PfD},
+    sercom,
+    target_device::{interrupt, Interrupt},
+    time::*,
+    CorePeripherals, Peripherals,
+};
+
+// I²C on trinket is on SERCOM2
+
+static mut LED: usize = 0;
+
+static HANDLERS: HandlerArray = HandlerArray::new();
+
+#[entry]
+fn main() -> ! {
+    let mut cp = CorePeripherals::take().expect("taking core peripherals");
+    let mut dp = Peripherals::take().expect("taking device peripherals");
+
+    let mut clocks = GenericClockController::with_internal_32kosc(
+        dp.GCLK,
+        &mut dp.PM,
+        &mut dp.SYSCTRL,
+        &mut dp.NVMCTRL,
+    );
+
+    let mut pins = hal::Pins::new(dp.PORT);
+
+    let uart = hal::uart(
+        &mut clocks,
+        115_200.hz(),
+        dp.SERCOM0,
+        &mut cp.NVIC,
+        &mut dp.PM,
+        pins.d3,
+        pins.d4,
+        &mut pins.port,
+    );
+
+    let mut red_led = pins.d13.into_open_drain_output(&mut pins.port);
+    red_led.set_low().expect("turning off red LED");
+    unsafe { LED = mem::transmute(&red_led) }
+
+    let mut dotstar = dotstar::new(
+        dp.SERCOM1,
+        pins.swdio,
+        pins.dotstar_di,
+        pins.dotstar_ci,
+        &mut pins.port,
+        &mut dp.PM,
+        &mut clocks,
+    );
+    let black = [colors::BLACK];
+    dotstar
+        .write(black.iter().cloned())
+        .expect("turning off dotstar");
+
+    // We do the transmute because, while all the underlying data is
+    // static, we're unable to get a referecence to the UART or LED
+    // until run-time. Another option would be to use Option in the
+    // SerialLogger definition, but that requires a check every time
+    // they might be used.
+    let uart_wrapped = logger::WriteWrapper::new(uart);
+    let logger = logger::SerialLogger::new(uart_wrapped, red_led);
+
+    // Wow, would I love to not be annotating this type.
+    let logger_ref: &'static logger::SerialLogger<
+        sercom::UART0<sercom::Sercom0Pad3<Pa7<PfD>>, sercom::Sercom0Pad2<Pa6<PfD>>, (), ()>,
+        Pa10<Output<OpenDrain>>,
+    > = unsafe { mem::transmute(&logger) };
+    unsafe { log::set_logger_racy(logger_ref).expect("couldn't set logger") };
+    log::set_max_level(LevelFilter::Trace);
+
+    let mut rtc_handler = rtc::setup(dp.RTC, &mut clocks);
+
+    HANDLERS.with_overrides(|hs| {
+        hs.register(0, &mut rtc_handler);
+        cp.NVIC.enable(Interrupt::RTC);
+
+        info!("Bootstrap complete.");
+
+        loop {
+            wfi()
+        }
+    });
+    unreachable!();
+}
+
+#[panic_handler]
+fn panic_handler(pi: &PanicInfo) -> ! {
+    let red_led: &mut Pa10<Output<OpenDrain>> = unsafe { mem::transmute(LED) };
+    red_led.set_high().ok();
+
+    logln_now!("~~~ PANIC ~~~");
+    logln_now!("{}", pi);
+    logln_now!("flushing log");
+    loop {
+        log::logger().flush();
+        wfi()
+    }
+}
+
+#[exception]
+fn HardFault(ef: &ExceptionFrame) -> ! {
+    let red_led: &mut Pa10<Output<OpenDrain>> = unsafe { mem::transmute(LED) };
+    red_led.set_high().ok();
+
+    log::logger().flush();
+    logln_now!("!!! Hard Fault - ef: {:?} !!!", ef);
+    logln_now!("flushing log");
+    loop {
+        log::logger().flush();
+        wfi()
+    }
+}
+
+#[interrupt]
+fn RTC() {
+    HANDLERS.call(0);
+}
+
+#[interrupt]
+fn USB() {
+    HANDLERS.call(1);
+}
diff --git a/src/rtc.rs b/src/rtc.rs
new file mode 100644
index 0000000..79e450a
--- /dev/null
+++ b/src/rtc.rs
@@ -0,0 +1,74 @@
+use core::sync::atomic::{AtomicUsize, Ordering};
+use log;
+use trinket_m0::{clock::GenericClockController, RTC};
+
+struct Clock(AtomicUsize);
+impl Clock {
+    const fn new() -> Self {
+        Self(AtomicUsize::new(0))
+    }
+
+    fn set(&self, millis: usize) {
+        self.0.store(millis, Ordering::SeqCst)
+    }
+
+    // Slightly less than 1ms, due to using a 32,768Hz clock, we can't
+    // hit exactly 1ms, so we shoot for a bit under.
+    fn millis(&self) -> usize {
+        self.0.load(Ordering::SeqCst)
+    }
+}
+
+static CLOCK: Clock = Clock::new();
+
+// Set to run every ~500µs.
+static COUNTER: u32 = 16; // 32 ticks requires 1024 cycles at 32,768Hz for 1 second.
+
+pub fn setup(mut rtc: RTC, clocks: &mut GenericClockController) -> impl FnMut() {
+    let rtc_clock = &clocks.gclk1();
+    clocks.rtc(&rtc_clock);
+
+    rtc.mode0().ctrl.write(|w| w.swrst().set_bit());
+    while rtc.mode0().status.read().syncbusy().bit_is_set() {}
+
+    rtc.mode0().ctrl.write(|w| {
+        w.mode().count32();
+
+        // Neither the prescaler nor matchlr values seem to work. Not
+        // sure why.
+        //w.prescaler().div1024();
+        w.matchclr().set_bit() // Reset on match for periodic
+    });
+
+    rtc.mode0().comp[0].write(|w| unsafe { w.bits(COUNTER) });
+    rtc.mode0().intflag.write(|w| w.cmp0().set_bit());
+    rtc.mode0().intenset.write(|w| w.cmp0().set_bit());
+
+    // Enable the RTC and wait for sync.
+    rtc.mode0().ctrl.write(|w| w.enable().set_bit());
+    while rtc.mode0().status.read().syncbusy().bit_is_set() {}
+
+    move || handler(&mut rtc)
+}
+
+pub fn millis() -> usize {
+    CLOCK.millis()
+}
+
+fn handler(rtc: &mut RTC) {
+    // FIXME: matchclr doesn't seem to work to reset the counter?
+    rtc.mode0().count.write(|w| unsafe { w.bits(0) });
+    rtc.mode0().intflag.write(|w| w.cmp0().set_bit());
+
+    static mut TICKS: usize = 0;
+    static mut ADD: bool = false;
+    unsafe {
+        if ADD {
+            TICKS += 1;
+            CLOCK.set(TICKS);
+        }
+        ADD = !ADD;
+
+        log::logger().flush();
+    }
+}