usb peripheral now starting ‘connect()’

6 files changed, 963 insertions, 11 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 7b0fdc3..ff4e28f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -103,6 +103,8 @@ dependencies = [
  "nb 1.0.0",
  "riscv 0.8.0",
  "riscv-rt",
+ "usb-device",
+ "usbd-serial",
 ]
 
 [[package]]
@@ -285,6 +287,23 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c4f5b37a154999a8f3f98cc23a628d850e154479cd94decf3414696e12e31aaf"
 
 [[package]]
+name = "usb-device"
+version = "0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1f6cc3adc849b5292b4075fc0d5fdcf2f24866e88e336dd27a8943090a520508"
+
+[[package]]
+name = "usbd-serial"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "db75519b86287f12dcf0d171c7cf4ecc839149fe9f3b720ac4cfce52959e1dfe"
+dependencies = [
+ "embedded-hal",
+ "nb 0.1.3",
+ "usb-device",
+]
+
+[[package]]
 name = "vcell"
 version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/Cargo.toml b/Cargo.toml
index 3a8e031..ab7756a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -23,6 +23,8 @@ riscv = "0.8.0"
 riscv-rt = "0.9.0"
 nb = "1.0.0"
 embedded-hal = "0.2.7"
+usb-device = "0.2.9"
+usbd-serial = "0.1.1"
 
 [[bin]]
 name = "luchie"
diff --git a/src/blink.rs b/src/blink.rs
index 8e17b21..bb53845 100644
--- a/src/blink.rs
+++ b/src/blink.rs
@@ -6,7 +6,7 @@ use gd32vf103xx_hal::{
     eclic::{self, EclicExt},
     pac::{self, Interrupt},
     time::Hertz,
-    timer,
+    timer::{Event, Timer},
 };
 use nb;
 
@@ -18,20 +18,20 @@ enum State {
 }
 
 pub struct Task {
-    timer: timer::Timer<pac::TIMER6>,
+    timer: Timer<pac::TIMER6>,
     frequency: Hertz,
     led: LED,
     state: State,
 }
 
 impl Task {
-    pub fn new(mut timer: timer::Timer<pac::TIMER6>, frequency: Hertz, led: LED) -> Self {
+    pub fn new(mut timer: Timer<pac::TIMER6>, frequency: Hertz, led: LED) -> Self {
         pac::ECLIC::setup(Interrupt::TIMER6, eclic::TriggerType::RisingEdge, eclic::Level::L0, eclic::Priority::P3);
         unsafe { pac::ECLIC::unmask(Interrupt::TIMER6); }
         if !pac::ECLIC::is_enabled(Interrupt::TIMER6) {
             panic!("timer6 interrupt not enabled");
         }
-        timer.listen(timer::Event::Update);
+        timer.listen(Event::Update);
 
         Self { timer, frequency, led, state: State::ToggleLED }
     }
@@ -41,6 +41,7 @@ impl Task {
             State::WaitForTimer => {
                 if let Ok(_) = self.timer.wait() {
                     self.state = State::ToggleLED;
+                    // self.timer.unlisten(Event::Update);
                     Ok(())
                 } else {
                     Err(nb::Error::WouldBlock)
@@ -50,6 +51,7 @@ impl Task {
                 self.led.toggle();
                 self.timer.start(self.frequency);
                 self.state = State::WaitForTimer;
+                // self.timer.listen(Event::Update);
                 Err(nb::Error::WouldBlock)
             }
         }
diff --git a/src/log.rs b/src/log.rs
index b6204d6..ddb6792 100644
--- a/src/log.rs
+++ b/src/log.rs
@@ -9,7 +9,7 @@ use riscv::interrupt::{self, Mutex};
 #[macro_export]
 macro_rules! log {
     ($($args:tt)+) => {
-        $crate::log::log_args(core::format_args!($($args)+));
+        $crate::log::log_args(core::format_args!($($args)+))
     }
 }
 
@@ -17,7 +17,7 @@ macro_rules! log {
 macro_rules! logln {
     () => ({ kprint!("\r\n") });
     ($fmt: literal $(, $($arg: tt)+)?) => {
-        log!(concat!($fmt, "\n") $(, $($arg)+)?);
+        log!(concat!($fmt, "\n") $(, $($arg)+)?)
     }
 }
 
diff --git a/src/main.rs b/src/main.rs
index 6cb4139..19f2b7a 100755
--- a/src/main.rs
+++ b/src/main.rs
@@ -4,15 +4,17 @@
 mod blink;
 mod led;
 mod log;
+mod usb;
 
 use gd32vf103xx_hal::{
     afio::AfioExt,
     eclic::{self, EclicExt},
+    exti::Exti,
     gpio::GpioExt,
     pac::{self, Peripherals},
     rcu::RcuExt,
     serial::Serial,
-    time::Hertz,
+    time::{Hertz, MegaHertz},
     timer::Timer,
 };
 use riscv::{
@@ -29,10 +31,11 @@ use led::LED;
 fn main(_hartid: usize) -> ! {
     let p = Peripherals::take().expect("couldn't take peripherals");
 
+    pac::ECLIC::reset();
     pac::ECLIC::set_threshold_level(eclic::Level::L0);
     pac::ECLIC::set_level_priority_bits(eclic::LevelPriorityBits::L3P1);
 
-    let mut rcu = p.RCU.configure().freeze();
+    let mut rcu = p.RCU.configure().sysclk(MegaHertz(48)).freeze();
     let mut afio = p.AFIO.constrain(&mut rcu);
     let gpioa = p.GPIOA.split(&mut rcu);
 
@@ -49,22 +52,45 @@ fn main(_hartid: usize) -> ! {
     let (tx, _rx) = serial.split();
     log::init(tx);
 
-    let timer = Timer::<pac::TIMER6>::timer6(p.TIMER6, Hertz(1), &mut rcu);
+    let timer = Timer::<pac::TIMER6>::timer6(p.TIMER6, Hertz(5), &mut rcu);
     let led = LED::new(gpioa.pa7);
     let mut blink = blink::Task::new(timer, Hertz(5), led);
 
+    logln!("+++ busabus");
+    let mut exti = Exti::new(p.EXTI);
+    let bus = usb::Bus::new(p.USBFS_GLOBAL, p.USBFS_DEVICE, p.USBFS_PWRCLK, &mut rcu, &mut exti);
+    bus.init();
+    // let bus_alloc = UsbBusAllocator::new(bus);
+    // logln!("+++ devadev");
+    // let mut usb_dev = UsbDeviceBuilder::new(&bus_alloc, UsbVidPid(0xdead, 0xbeef))
+    //     .manufacturer("luchie")
+    //     .product("pad")
+    //     .serial_number("test")
+    //     .build();
+    // logln!("+++ superserious");
+    //let mut serial = SerialPort::new(&bus_alloc);
+
+    unsafe { interrupt::enable() };
+
     loop {
         let mut can_sleep = true;
 
+        log!("yo");
         if let Ok(_) = blink.poll() {
             can_sleep = false;
         }
-        log!("yo!");
-        logln!(" mtv raps");
+        log!(" mtv");
+        // was: usb_dev.poll(&mut [&mut serial])
+        // if usb_dev.poll(&mut []) {
+        //     can_sleep = false;
+        // }
+        log!(" raps");
 
         if can_sleep {
+            log!("!");
             unsafe { wfi() };
         }
+        logln!("");
     }
 }
 
diff --git a/src/usb.rs b/src/usb.rs
new file mode 100644
index 0000000..c6920e1
--- /dev/null
+++ b/src/usb.rs
@@ -0,0 +1,903 @@
+//use embedded_hal::digital::v2::OutputPin;
+use gd32vf103xx_hal::prelude::_embedded_hal_blocking_delay_DelayMs;
+use gd32vf103xx_hal::{
+    eclic::{EclicExt, Level, Priority, TriggerType},
+    exti::{Exti, ExtiLine, InternalLine, TriggerEdge},
+    pac::{ECLIC, Interrupt, RCU, USBFS_DEVICE, USBFS_GLOBAL, USBFS_PWRCLK},
+    rcu::Rcu,
+    time::MegaHertz,
+};
+use riscv::{
+    asm::delay,
+    interrupt,
+};
+use usb_device::{
+    class_prelude::*,
+    bus::PollResult,
+    UsbDirection,
+};
+
+use crate::{log, logln};
+
+struct EPAllocation(u8);
+impl EPAllocation {
+    const MAX_ENDPOINT: usize = 4;
+
+    fn new() -> Self {
+        EPAllocation(0)
+    }
+
+    fn is_alloc(&self, index: usize) -> Result<bool, UsbError> {
+        if index < Self::MAX_ENDPOINT {
+            let test = 1 << index;
+            logln!("is_alloc: {} & {} = {}", self.0, test, self.0 & test == test);
+            Ok(self.0 & test == test)
+        } else {
+            logln!("is_alloc underflow");
+            Err(UsbError::EndpointOverflow)
+        }
+    }
+
+    fn is_free(&self, index: usize) -> Result<bool, UsbError> {
+        self.is_alloc(index).map(|v| !v)
+    }
+
+    fn alloc(&mut self, index: usize) -> Result<(), UsbError> {
+        if index < Self::MAX_ENDPOINT {
+            let test = 1 << index;
+            self.0 |= test;
+            logln!("alloc: {} & {}", self.0, test);
+            Ok(())
+        } else {
+            logln!("alloc underflow");
+            Err(UsbError::EndpointOverflow)
+        }
+    }
+
+    fn next_ep(&self) -> Result<usize, UsbError> {
+        for i in 0..Self::MAX_ENDPOINT {
+            if self.is_free(i)? {
+                logln!("next: {}", i);
+                return Ok(i)
+            }
+        }
+        logln!("next underflow");
+        Err(UsbError::EndpointOverflow)
+    }
+
+    fn iter(&self) -> EPAllocationIter {
+        EPAllocationIter { i: 0, alloc: self }
+    }
+}
+
+struct EPAllocationIter<'a> {
+    i: u8,
+    alloc: &'a EPAllocation,
+}
+
+impl Iterator for EPAllocationIter<'_> {
+    type Item = u8;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        while let Ok(is_alloc) = self.alloc.is_alloc(self.i.into()) {
+            self.i += 1;
+            if is_alloc {
+                return Some(self.i - 1);
+            }
+        }
+        None
+    }
+}
+
+pub struct Bus {
+    usbg: USBFS_GLOBAL,
+    usbd: USBFS_DEVICE,
+    usbpwr: USBFS_PWRCLK,
+
+    ep_in_alloc: EPAllocation,
+    ep_out_alloc: EPAllocation,
+}
+
+fn rcu_config(rcu: &mut Rcu) {
+    let system_clock = rcu.clocks.sysclk();
+    let psc: u8 = if system_clock == MegaHertz(48).into() {
+        logln!("48mhz");
+        0b01
+    } else if system_clock == MegaHertz(72).into() {
+        logln!("72mhz");
+        0b00
+    } else if system_clock == MegaHertz(96).into() {
+        logln!("96mhz");
+        0b11
+    } else {
+        logln!("clk: {}", system_clock.0);
+        0b01
+    };
+    // rcu_usb_clock_config(psc)
+    let rcup = unsafe { &*RCU::ptr() };
+    rcup.cfg0.modify(|_, w| unsafe { w.usbfspsc().bits(psc) });
+
+    // Enable USB peripheral
+    rcup.ahben.modify(|_, w| w.usbfsen().set_bit());
+    // Reset USB peripheral
+    // rcup.ahbrst.modify(|_, w| w.usbfsrst().set_bit());
+    // rcup.ahbrst.modify(|_, w| w.usbfsrst().clear_bit());
+
+}
+
+fn intr_config(exti: &mut Exti) {
+    ECLIC::setup(Interrupt::USBFS, TriggerType::RisingEdge, Level::L1, Priority::P0);
+
+    let rcup = unsafe { &*RCU::ptr() };
+
+    // Enable PMU clock
+    rcup.apb1en.modify(|_, w| w.pmuen().set_bit());
+
+    // Reset USB peripheral
+    rcup.apb1rst.modify(|_, w| w.pmurst().set_bit());
+    rcup.apb1rst.modify(|_, w| w.pmurst().clear_bit());
+
+    let line = ExtiLine::from_internal_line(InternalLine::UsbWakeup);
+    Exti::clear(line);
+    exti.listen(line, TriggerEdge::Rising);
+
+    ECLIC::setup(Interrupt::USBFS_WKUP, TriggerType::RisingEdge, Level::L1, Priority::P0);
+
+    unsafe {
+        ECLIC::unmask(Interrupt::USBFS);
+        ECLIC::unmask(Interrupt::USBFS_WKUP);
+    }
+}
+
+impl Bus {
+    pub fn new(
+        usbg: USBFS_GLOBAL,
+        usbd: USBFS_DEVICE,
+        usbpwr: USBFS_PWRCLK,
+        rcu: &mut Rcu,
+        exti: &mut Exti,
+    ) -> Self {
+        /*
+        eclic_global_interrupt_enable();
+
+        eclic_priority_group_set(ECLIC_PRIGROUP_LEVEL2_PRIO2);
+
+        usb_rcu_config();
+
+        usb_timer_init();
+
+        usb_intr_config();
+
+        usbd_init (&USB_OTG_dev, USB_CORE_ENUM_FS, &usbd_cdc_cb);
+
+         */
+        rcu_config(rcu);
+
+        intr_config(exti);
+
+        let ep_in_alloc = EPAllocation::new();
+        let ep_out_alloc = EPAllocation::new();
+        Self { usbg, usbd, usbpwr, ep_in_alloc, ep_out_alloc }
+    }
+
+    fn basic_init(&self) {
+        // transfer_mode = use_fifo
+        // core_speed = full
+        // core_enum = 1 (FS) (HS is 0)
+        //        reg_base = USBFS_REG_BASE;
+
+        /* set the host channel numbers */
+        // usb_basic->num_pipe = USBFS_MAX_CHANNEL_COUNT;
+
+        // /* set the device endpoint numbers */
+        // usb_basic->num_ep = USBFS_MAX_EP_COUNT;
+
+        // /* USBFS core use embedded physical layer */
+        // usb_basic->phy_itf = USB_EMBEDDED_PHY;
+   // usb_basic->sof_enable = USB_SOF_OUTPUT; /* 1 in cdcacm */
+   //  usb_basic->low_power = USB_LOW_POWER; /* 1 in cdcacm */
+    }
+
+    fn mdelay(d: u32) {
+        let mut delay = riscv::delay::McycleDelay::new(108_000);
+        delay.delay_ms(d);
+    }
+
+    fn udelay(d: u32) {
+        let mut delay = riscv::delay::McycleDelay::new(108);
+        delay.delay_ms(d);
+    }
+
+    fn core_reset(&self) {
+        self.usbg.grstctl.modify(|_, w| w.csrst().set_bit());
+        while self.usbg.grstctl.read().csrst().bit_is_set() {}
+        Self::udelay(3);
+    }
+
+    fn core_init(&self) {
+        self.usbg.gahbcs.modify(|_, w| w.ginten().clear_bit());
+        // this sets a reserved field to a magic value, and i hope
+        // it's not neccessary.
+        self.usbg.gusbcs.modify(|r, w| unsafe { w.bits(r.bits() | 1 << 6) });
+        logln!("-> core_reset");
+        self.core_reset();
+        logln!("<- core_reset");
+        self.usbg.gccfg.modify(|_, w| {
+            w
+                .pwron().set_bit()
+                .vbusacen().set_bit()
+                .vbusbcen().set_bit()
+                .sofoen().set_bit()
+        });
+
+        Self::mdelay(20);
+    }
+
+    fn devdisconnect(&self) {
+        self.usbd.dctl.modify(|_, w| w.sd().set_bit());
+    }
+
+    fn disconnect(&self) {
+        self.devdisconnect();
+        Self::mdelay(3);
+    }
+
+    // 32 bit words
+    const RX_FIFO_SIZE: u16 = 128;
+    const TX_FIFO_SIZE: [u16; 4] = [64, 128, 0, 0];
+
+    fn devint_enable(&self) {
+        self.usbg.gotgintf.write(|w| unsafe { w.bits(0xffff_ffffu32) });
+        self.usbg.gintf.write(|w| unsafe { w.bits(0xbfff_ffffu32) });
+        self.usbg.ginten.modify(|_, w| {
+            w
+                .wkupie().set_bit()
+                .spie().set_bit()
+                .rxfneie().set_bit()
+                .rstie().set_bit()
+                .enumfie().set_bit()
+                .iepie().set_bit()
+                .oepie().set_bit()
+                .sofie().set_bit()
+                .mfie().set_bit()
+        });
+        self.usbg.gahbcs.modify(|_, w| w.ginten().set_bit());
+    }
+
+    fn txfifo_flush(&self, fifo_num: u8) {
+        self.usbg.grstctl.modify(|_, w| {
+            unsafe {
+                w
+                    .txfnum().bits(fifo_num)
+                    .txff().set_bit()
+            }
+        });
+        while self.usbg.grstctl.read().txff().bit_is_set() {}
+
+        Self::mdelay(3);
+    }
+
+    fn rxfifo_flush(&self) {
+        self.usbg.grstctl.modify(|_, w| w.txff().set_bit());
+        while self.usbg.grstctl.read().txff().bit_is_set() {}
+
+        Self::mdelay(3);
+    }
+
+    fn devcore_init(&self) {
+        self.usbg.gusbcs.modify(|_, w| {
+            w
+                .fdm().clear_bit()
+                .fhm().clear_bit()
+        });
+        self.usbg.gusbcs.modify(|_, w| w.fdm().set_bit());
+        self.usbpwr.pwrclkctl.modify(|_, w| unsafe { w.bits(0) });
+        self.usbd.dcfg.modify(|_, w| {
+            unsafe {
+                w
+                    .eopft().bits(0)
+                    .ds().bits(0b11)
+            }
+        });
+        self.usbg.grflen.modify(|_, w| unsafe { w.rxfd().bits(Self::RX_FIFO_SIZE)});
+        self.usbg.hnptflen().modify(|_, w| {
+            unsafe {
+                w
+                    .hnptxfd().bits(Self::TX_FIFO_SIZE[0])
+                    .hnptxrsar().bits(Self::RX_FIFO_SIZE)
+            }
+        });
+        let mut ram_addr = Self::RX_FIFO_SIZE;
+
+        ram_addr += Self::TX_FIFO_SIZE[0];
+        self.usbg.diep1tflen.modify(|_, w| {
+            unsafe {
+                w
+                    .ieptxfd().bits(Self::TX_FIFO_SIZE[1])
+                    .ieptxrsar().bits(ram_addr)
+            }
+        });
+        ram_addr += Self::TX_FIFO_SIZE[1];
+        self.usbg.diep1tflen.modify(|_, w| {
+            unsafe {
+                w
+                    .ieptxfd().bits(Self::TX_FIFO_SIZE[2])
+                    .ieptxrsar().bits(ram_addr)
+            }
+        });
+        ram_addr += Self::TX_FIFO_SIZE[2];
+        self.usbg.diep1tflen.modify(|_, w| {
+            unsafe {
+                w
+                    .ieptxfd().bits(Self::TX_FIFO_SIZE[3])
+                    .ieptxrsar().bits(ram_addr)
+            }
+        });
+
+        self.txfifo_flush(0x10);
+        self.rxfifo_flush();
+
+        self.usbd.diepinten.modify(|_, w| unsafe { w.bits(0) });
+        self.usbd.doepinten.modify(|_, w| unsafe { w.bits(0) });
+        self.usbd.daepinten.modify(|_, w| unsafe { w.bits(0) });
+        // read-only in the pac and datasheet
+        //self.usbd.daepint.modify(|_, w| unsafe { w.bits(0xffff_ffffu32) });
+
+        if self.usbd.diep0ctl.read().epen().bit_is_set() {
+            self.usbd.diep0ctl.modify(|_, w| w.epd().set_bit().snak().set_bit());
+        } else {
+            self.usbd.diep0ctl.write(|w| unsafe { w.bits(0) });
+        }
+        self.usbd.diep0len.write(|w| unsafe { w.bits(0) });
+        self.usbd.diep0intf.write(|w| unsafe { w.bits(0xff) });
+
+        if self.usbd.doep0ctl.read().epen().bit_is_set() {
+            self.usbd.doep0ctl.modify(|_, w| w.snak().set_bit());
+        } else {
+            self.usbd.doep0ctl.write(|w| unsafe { w.bits(0) });
+        }
+        self.usbd.doep0len.write(|w| unsafe { w.bits(0) });
+        self.usbd.doep0intf.write(|w| unsafe { w.bits(0xff) });
+
+        if self.usbd.diep1ctl.read().epen().bit_is_set() {
+            self.usbd.diep1ctl.modify(|_, w| w.epd().set_bit().snak().set_bit());
+        } else {
+            self.usbd.diep1ctl.write(|w| unsafe { w.bits(0) });
+        }
+        self.usbd.diep1len.write(|w| unsafe { w.bits(0) });
+        self.usbd.diep1intf.write(|w| unsafe { w.bits(0xff) });
+
+        if self.usbd.doep1ctl.read().epen().bit_is_set() {
+            self.usbd.doep1ctl.modify(|_, w| w.epd().set_bit().snak().set_bit());
+        } else {
+            self.usbd.doep1ctl.write(|w| unsafe { w.bits(0) });
+        }
+        self.usbd.doep1len.write(|w| unsafe { w.bits(0) });
+        self.usbd.doep1intf.write(|w| unsafe { w.bits(0xff) });
+
+        if self.usbd.diep2ctl.read().epen().bit_is_set() {
+            self.usbd.diep2ctl.modify(|_, w| w.epd().set_bit().snak().set_bit());
+        } else {
+            self.usbd.diep2ctl.write(|w| unsafe { w.bits(0) });
+        }
+        self.usbd.diep2len.write(|w| unsafe { w.bits(0) });
+        self.usbd.diep2intf.write(|w| unsafe { w.bits(0xff) });
+
+        if self.usbd.doep2ctl.read().epen().bit_is_set() {
+            self.usbd.doep2ctl.modify(|_, w| w.epd().set_bit().snak().set_bit());
+        } else {
+            self.usbd.doep2ctl.write(|w| unsafe { w.bits(0) });
+        }
+        self.usbd.doep2len.write(|w| unsafe { w.bits(0) });
+        self.usbd.doep2intf.write(|w| unsafe { w.bits(0xff) });
+
+        if self.usbd.diep3ctl.read().epen().bit_is_set() {
+            self.usbd.diep3ctl.modify(|_, w| w.epd().set_bit().snak().set_bit());
+        } else {
+            self.usbd.diep3ctl.write(|w| unsafe { w.bits(0) });
+        }
+        self.usbd.diep3len.write(|w| unsafe { w.bits(0) });
+        self.usbd.diep3intf.write(|w| unsafe { w.bits(0xff) });
+
+        if self.usbd.doep3ctl.read().epen().bit_is_set() {
+            self.usbd.doep3ctl.modify(|_, w| w.epd().set_bit().snak().set_bit());
+        } else {
+            self.usbd.doep3ctl.write(|w| unsafe { w.bits(0) });
+        }
+        self.usbd.doep3len.write(|w| unsafe { w.bits(0) });
+        self.usbd.doep3intf.write(|w| unsafe { w.bits(0xff) });
+
+
+        self.devint_enable();
+    }
+
+    fn devconnect(&self) {
+        self.usbd.dctl.modify(|_, w| w.sd().clear_bit());
+    }
+
+    fn connect(&self) {
+        self.devconnect();
+        Self::mdelay(3);
+    }
+
+    pub fn init(&self) {
+        logln!("!!! basic_init");
+        self.basic_init();
+        logln!("!!! core_init");
+        self.core_init();
+        logln!("!!! disconnect");
+        self.disconnect();
+        logln!("!!! devcore_init");
+        self.devcore_init();
+        logln!("!!! connect");
+        self.connect();
+
+        // cur_status = default;
+    }
+}
+
+unsafe impl Sync for Bus {}
+
+fn mpl_from_int(i: usize) -> Result<u8, UsbError> {
+    match i {
+        64 => Ok(0b00),
+        32 => Ok(0b01),
+        16 => Ok(0b10),
+        8  => Ok(0b11),
+        _  => Err(UsbError::Unsupported),
+    }
+}
+
+trait ToBits {
+    type Width;
+    fn to_bits(&self) -> Self::Width;
+}
+
+impl ToBits for EndpointType {
+    type Width = u8;
+
+    fn to_bits(&self) -> Self::Width {
+        match self {
+            EndpointType::Control     => 0b00,
+            EndpointType::Isochronous => 0b01,
+            EndpointType::Bulk        => 0b10,
+            EndpointType::Interrupt   => 0b11,
+        }
+    }
+}
+
+impl UsbBus for Bus {
+    // TODO: just allocate. enable() is called after this and can
+    // enable the endpoints. gets called with ep0
+    fn alloc_ep(
+        &mut self,
+        dir: UsbDirection,
+        ep_addr: Option<EndpointAddress>,
+        ep_type: EndpointType,
+        max_packet_size: u16,
+        _interval: u8
+    ) -> Result<EndpointAddress, UsbError> {
+        logln!("--- alloc_ep {:?} {:?} {:?} {}", dir, ep_addr, ep_type, max_packet_size);
+        let fd = self.usbg.hptflen.read().hptxfd().bits();
+        let sar = self.usbg.hptflen.read().hptxfsar().bits();
+        logln!("fd: 0x{:08x} sar: 0x{:08x}", fd, sar);
+        let ep_alloc = if dir == UsbDirection::Out {
+            &mut self.ep_out_alloc
+        } else {
+            &mut self.ep_in_alloc
+        };
+        interrupt::free(|_cs| {
+            let mpl = mpl_from_int(max_packet_size as usize)?;
+            let next = {
+                let a = ep_alloc.next_ep()?;
+                EndpointAddress::from_parts(a, dir)
+            };
+            let addr = match ep_addr {
+                None => next,
+                Some(a) => {
+                    if ep_alloc.is_free(a.index())? {
+                        a
+                    } else {
+                        return Err(UsbError::InvalidEndpoint);
+                    }
+                },
+            };
+            let eptype = ep_type.to_bits();
+            // i yield! i can think of no good way to cover all cases
+            // without macros.
+            unsafe {
+                logln!("checking dir/idx");
+                match (dir, addr.index()) {
+                    (_, 0) => {
+                        let nfd = self.usbg.diep0tflen().read().iep0txfd().bits();
+                        let nsar = self.usbg.diep0tflen().read().iep0txrsar().bits();
+                        logln!("{}ifd: 0x{:08x} sar: 0x{:08x}", 0, nfd, nsar);
+                        self.usbd.diep0ctl.modify(|_, w| {
+                            w
+                                .bits(mpl.into())
+                                .epen().clear_bit()
+                        });
+
+                        self.usbd.doep0ctl.modify(|_, w| {
+                            w
+                                .bits(mpl.into())
+                                .epen().clear_bit()
+                        });
+                    }
+
+                    (UsbDirection::In, 1) => {
+                        let nfd = self.usbg.diep1tflen.read().ieptxfd().bits();
+                        let nsar = self.usbg.diep1tflen.read().ieptxrsar().bits();
+                        logln!("{}ifd: 0x{:08x} sar: 0x{:08x}", 1, nfd, nsar);
+                        self.usbd.diep1ctl.modify(|_, w| {
+                            w
+                                .eptype().bits(eptype)
+                                .mpl().bits(mpl.into())
+                                .epen().clear_bit()
+                        });
+                    }
+                    (UsbDirection::Out, 1) => {
+                        self.usbd.doep1ctl.modify(|_, w| {
+                            w
+                                .eptype().bits(eptype)
+                                .mpl().bits(mpl.into())
+                                .epen().clear_bit()
+                        });
+                    }
+                    (UsbDirection::In, 2) => {
+                        let nfd = self.usbg.diep2tflen.read().ieptxfd().bits();
+                        let nsar = self.usbg.diep2tflen.read().ieptxrsar().bits();
+                        logln!("{}ifd: 0x{:08x} sar: 0x{:08x}", 2, nfd, nsar);
+                        self.usbd.diep2ctl.modify(|_, w| {
+                            w
+                                .eptype().bits(eptype)
+                                .mpl().bits(mpl.into())
+                                .epen().clear_bit()
+                        });
+                    }
+                    (UsbDirection::Out, 2) => {
+                        self.usbd.doep2ctl.modify(|_, w| {
+                            w
+                                .eptype().bits(eptype)
+                                .mpl().bits(mpl.into())
+                                .epen().clear_bit()
+                        });
+                    }
+                    (UsbDirection::In, 3) => {
+                        let nfd = self.usbg.diep3tflen.read().ieptxfd().bits();
+                        let nsar = self.usbg.diep3tflen.read().ieptxrsar().bits();
+                        logln!("{}ifd: 0x{:08x} sar: 0x{:08x}", 3, nfd, nsar);
+                        self.usbd.diep3ctl.modify(|_, w| {
+                            w
+                                .eptype().bits(eptype)
+                                .mpl().bits(mpl.into())
+                                .epen().clear_bit()
+                        });
+                    }
+                    (UsbDirection::Out, 3) => {
+                        self.usbd.doep3ctl.modify(|_, w| {
+                            w
+                                .eptype().bits(eptype)
+                                .mpl().bits(mpl.into())
+                                .epen().clear_bit()
+                        });
+                    }
+                    (dir, ep) => {
+                        logln!("--- couldn't alloc ep for {:?} {}", dir, ep);
+                        return Err(UsbError::EndpointOverflow)
+                    },
+                }
+            }
+
+            ep_alloc.alloc(addr.index())?;
+            logln!("--- allocated ep for {:?} {}", dir, addr.index());
+            Ok(addr)
+        })
+    }
+
+    // reset() is called after this. start enumeration there
+    fn enable(&mut self) {
+        logln!("--- enable");
+        interrupt::free(|_cs| {
+            // power off the bus
+            self.usbg.gccfg.modify(|_, w| w.pwron().clear_bit());
+
+            self.usbg.gahbcs.modify(|_, w| w.ginten().clear_bit());
+
+            // See: [[file:~/src/GD32VF103_Firmware_Library/Firmware/GD32VF103_usbfs_driver/Include/drv_usb_regs.h::define GUSBCS_EMBPHY BIT(6) /*!< embedded PHY selected */]] and [[file:~/src/GD32VF103_Firmware_Library/Firmware/GD32VF103_usbfs_driver/Source/drv_usb_core.c::usb_regs->gr->GUSBCS |= GUSBCS_EMBPHY;]]
+            // GUSBCS_EMBPHY ?? bit 6
+            self.usbg.gusbcs.modify(|r, w| unsafe { w.bits(r.bits() | 1 << 6) });
+
+            // usb_core_reset
+            self.usbg.grstctl.modify(|_, w| w.csrst().set_bit());
+            while self.usbg.grstctl.read().csrst().bit_is_set() {}
+            unsafe { delay(108_000 * 3) };
+
+            self.usbg.gccfg.modify(|_, w| {
+                w
+                    .pwron().set_bit()
+                    .vbusacen().set_bit()
+                    .vbusbcen().set_bit()
+                    .sofoen().set_bit()
+            });
+
+            // delay 20ms
+            unsafe { delay(108_000 * 20) };
+
+            // RST should trigger when the host notices the device,
+            // which will proceed to ‘reset()’
+        });
+        logln!("--- enable: done");
+    }
+
+    // everything is allocated, the device is enabled. now reset
+    // everything to begin enumeration
+    fn reset(&self) {
+        logln!("--- reset");
+        // program d[oi]ep[0123]ctl
+        //         d[oi]epinten
+        //         d[oi]eplen
+        //         set epen in ctl reg
+
+        interrupt::free(|_cs| {
+            for ep in self.ep_out_alloc.iter() {
+                match ep {
+                    0 => self.usbd.doep0ctl.modify(|_, w| w.epen().set_bit()),
+                    1 => self.usbd.doep1ctl.modify(|_, w| w.epen().set_bit()),
+                    2 => self.usbd.doep2ctl.modify(|_, w| w.epen().set_bit()),
+                    3 => self.usbd.doep3ctl.modify(|_, w| w.epen().set_bit()),
+                    _ => (),
+                }
+            }
+
+            for ep in self.ep_in_alloc.iter() {
+                match ep {
+                    0 => self.usbd.diep0ctl.modify(|_, w| w.epen().set_bit()),
+                    1 => self.usbd.diep1ctl.modify(|_, w| w.epen().set_bit()),
+                    2 => self.usbd.diep2ctl.modify(|_, w| w.epen().set_bit()),
+                    3 => self.usbd.diep3ctl.modify(|_, w| w.epen().set_bit()),
+                    _ => (),
+                }
+            }
+
+            // wait for enum interrupt in gintf register
+        });
+    }
+
+    fn set_device_address(&self, address: u8) {
+        logln!("--- set_device_address");
+        interrupt::free(|_cs| {
+            self.usbd.dcfg.modify(|_, w| unsafe { w.dar().bits(address & 7) });
+        });
+    }
+
+    fn write(&self, _ep_addr: EndpointAddress, buf: &[u8]) -> Result<usize, UsbError> {
+        logln!("--- write");
+        assert!(buf.as_ptr() as u8 & 0b11 == 0);
+        interrupt::free(|_cs| {
+            // new - set ep fifo
+            self.usbg.diep1tflen.modify(|_, w| {
+                unsafe {
+                    w
+                    // depth (in 32 bit words)
+                        .ieptxfd().bits((buf.len() >> 2).try_into().unwrap())
+                    // ram start address (in 32 bit words)
+                        .ieptxrsar().bits((buf.as_ptr() as usize >> 2).try_into().unwrap())
+                }
+            });
+        });
+        Err(UsbError::WouldBlock)
+    }
+
+    fn read(&self, ep_addr: EndpointAddress, _buf: &mut [u8]) -> Result<usize, UsbError> {
+        logln!("--- read");
+        interrupt::free(|_cs| {
+            match ep_addr.index() {
+                0 => {
+                    let v = &self.usbd.doep0len;
+                    logln!("    0tlen: {}", v.read().tlen().bits());
+                    logln!("    0pcnt: {}", v.read().pcnt().bits());
+                    logln!("    0stpcnt: {}", v.read().stpcnt().bits());
+                },
+                1 => {
+                    let v = &self.usbd.doep1len;
+                    logln!("    1tlen: {}", v.read().tlen().bits());
+                    logln!("    1pcnt: {}", v.read().pcnt().bits());
+                    logln!("    1stpcnt_rxdpid: {}", v.read().stpcnt_rxdpid().bits());
+                },
+                2 => {
+                    let v = &self.usbd.doep1len;
+                    logln!("    2tlen: {}", v.read().tlen().bits());
+                    logln!("    2pcnt: {}", v.read().pcnt().bits());
+                    logln!("    2stpcnt_rxdpid: {}", v.read().stpcnt_rxdpid().bits());
+                },
+                3 => {
+                    let v = &self.usbd.doep1len;
+                    logln!("    3tlen: {}", v.read().tlen().bits());
+                    logln!("    3pcnt: {}", v.read().pcnt().bits());
+                    logln!("    3stpcnt_rxdpid: {}", v.read().stpcnt_rxdpid().bits());
+                },
+                ep => logln!("    bad ep {}", ep),
+            };
+
+            // rx fifo through grstatr/grstatp
+            let ep = usize::from(self.usbg.grstatr_device().read().epnum().bits());
+            let packet_waiting = self.usbg.grstatr_device().read().rpckst().bits() != 1;
+            logln!("    grstatr: {}", self.usbg.grstatr_device().read().bits());
+            logln!("    bcountn: {}", self.usbg.grstatr_device().read().bcount().bits());
+            logln!("    dpid: {}", self.usbg.grstatr_device().read().dpid().bits());
+            logln!("    rpckst: {}", self.usbg.grstatr_device().read().rpckst().bits());
+            logln!("    ep: {}, waiting: {}", ep, packet_waiting);
+            if packet_waiting && ep == ep_addr.index() {
+                logln!("    pkt match");
+                Ok(0)
+            } else {
+                logln!("    wouldblock");
+                Err(UsbError::WouldBlock)
+            }
+        })
+    }
+
+    fn set_stalled(&self, ep_addr: EndpointAddress, _stalled: bool) {
+        logln!("--- set_stalled");
+        let ep = ep_addr.index();
+        interrupt::free(|_cs| {
+            if ep_addr.direction() == UsbDirection::Out {
+                if self.ep_out_alloc.is_alloc(ep).is_ok() {
+                    match ep {
+                        0 => self.usbd.doep0ctl.modify(|_, w| w.stall().set_bit()),
+                        1 => self.usbd.doep1ctl.modify(|_, w| w.stall().set_bit()),
+                        2 => self.usbd.doep2ctl.modify(|_, w| w.stall().set_bit()),
+                        3 => self.usbd.doep3ctl.modify(|_, w| w.stall().set_bit()),
+                        _ => (),
+                    }
+                }
+            } else if let Ok(_) = self.ep_in_alloc.is_alloc(ep) {
+                match ep {
+                    0 => self.usbd.diep0ctl.modify(|_, w| w.epd().set_bit().stall().set_bit()),
+                    1 => self.usbd.diep1ctl.modify(|_, w| w.epd().set_bit().stall().set_bit()),
+                    2 => self.usbd.diep2ctl.modify(|_, w| w.epd().set_bit().stall().set_bit()),
+                    3 => self.usbd.diep3ctl.modify(|_, w| w.epd().set_bit().stall().set_bit()),
+                    _ => (),
+                }
+            }
+        })
+    }
+
+    fn is_stalled(&self, ep_addr: EndpointAddress) -> bool {
+        logln!("--- is_stalled");
+        let ep = ep_addr.index();
+        interrupt::free(|_cs| {
+            if ep_addr.direction() == UsbDirection::Out {
+                if self.ep_out_alloc.is_alloc(ep).is_ok() {
+                    match ep {
+                        0 => self.usbd.doep0ctl.read().stall().bit_is_set(),
+                        1 => self.usbd.doep1ctl.read().stall().bit_is_set(),
+                        2 => self.usbd.doep2ctl.read().stall().bit_is_set(),
+                        3 => self.usbd.doep3ctl.read().stall().bit_is_set(),
+                        _ => false,
+                    }
+                } else {
+                    false
+                }
+            } else if let Ok(_) = self.ep_in_alloc.is_alloc(ep) {
+                match ep {
+                    0 => self.usbd.diep0ctl.read().stall().bit_is_set(),
+                    1 => self.usbd.diep1ctl.read().stall().bit_is_set(),
+                    2 => self.usbd.diep2ctl.read().stall().bit_is_set(),
+                    3 => self.usbd.diep3ctl.read().stall().bit_is_set(),
+                    _ => false,
+                }
+            } else {
+                false
+            }
+        })
+    }
+
+    fn suspend(&self) {
+        logln!("--- suspend");
+        /*
+        __IO uint32_t devstat = udev->regs.dr->DSTAT;
+
+        if ((udev->bp.low_power) && (devstat & DSTAT_SPST)) {
+            /* switch-off the USB clocks */
+            *udev->regs.PWRCLKCTL |= PWRCLKCTL_SHCLK;
+
+            /* enter DEEP_SLEEP mode with LDO in low power mode */
+            pmu_to_deepsleepmode(PMU_LDO_LOWPOWER, WFI_CMD);
+        }
+         */
+    }
+
+    fn resume(&self) {
+        logln!("--- resume");
+        /*
+        if (USB_OTG_dev.bp.low_power) {
+            SystemInit();
+
+            rcu_usb_clock_config(usbfs_prescaler);
+
+            rcu_periph_clock_enable(RCU_USBFS);
+
+            usb_clock_active(&USB_OTG_dev);
+        }
+
+        exti_interrupt_flag_clear(EXTI_18);
+
+         */
+    }
+
+    fn poll(&self) -> PollResult {
+        logln!("--- poll");
+        let res = interrupt::free(|_cs| {
+            let intf = self.usbg.gintf.read();
+            if intf.rst().bit_is_set() {
+                PollResult::Reset
+            } else if intf.sp().bit_is_set() {
+                PollResult::Suspend
+            } else if intf.wkupif().bit_is_set() {
+                PollResult::Resume
+            } else {
+                let statd = self.usbg.grstatr_device().read();
+                let mut ep_setup = 0;
+                let mut ep_out = 0;
+                let mut ep_in_complete = 0;
+
+                // TODO: i don't know of any other way to see if there's a
+                // pending setup packet
+                if statd.rpckst().bits() != 1 {
+                    let ep = statd.epnum().bits();
+                    let is_setup = statd.rpckst().bits() & 0b10 == 0b10;
+                    if is_setup {
+                        ep_setup |= 1 << ep;
+                    } else {
+                        ep_out |= 1 << ep;
+                    }
+                }
+
+                if self.usbd.doep0intf.read().tf().bit_is_set() {
+                    ep_out |= 1 << 0;
+                }
+                if self.usbd.doep1intf.read().tf().bit_is_set() {
+                    ep_out |= 1 << 1;
+                }
+                if self.usbd.doep2intf.read().tf().bit_is_set() {
+                    ep_out |= 1 << 2;
+                }
+                if self.usbd.doep3intf.read().tf().bit_is_set() {
+                    ep_out |= 1 << 3;
+                }
+
+                if self.usbd.diep0intf.read().tf().bit_is_set() {
+                    ep_in_complete |= 1 << 0;
+                }
+                if self.usbd.diep1intf.read().tf().bit_is_set() {
+                    ep_in_complete |= 1 << 1;
+                }
+                if self.usbd.diep2intf.read().tf().bit_is_set() {
+                    ep_in_complete |= 1 << 2;
+                }
+                if self.usbd.diep3intf.read().tf().bit_is_set() {
+                    ep_in_complete |= 1 << 3;
+                }
+
+                if ep_setup != 0 || ep_out != 0 || ep_in_complete != 0 {
+                    PollResult::Data { ep_out, ep_in_complete, ep_setup }
+                } else {
+                    PollResult::None
+                }
+            }
+        });
+
+        log!("+++ poll: ");
+        match res {
+            PollResult::Reset => logln!("reset"),
+            PollResult::Suspend=> logln!("suspend"),
+            PollResult::Resume => logln!("resume"),
+            PollResult::Data{ep_out, ep_in_complete, ep_setup} => logln!("data(out: {}, in: {}, setup: {})", ep_out, ep_in_complete, ep_setup),
+            PollResult::None => logln!("none"),
+        }
+
+        res
+    }
+}