8 files changed, 548 insertions, 0 deletions

diff --git a/embassy-nrf/src/chips/nrf52810.rs b/embassy-nrf/src/chips/nrf52810.rs
index 7fe35b27f..9f3ed9cf3 100644
--- a/embassy-nrf/src/chips/nrf52810.rs
+++ b/embassy-nrf/src/chips/nrf52810.rs
@@ -114,6 +114,8 @@ impl_uarte!(UARTE0, UARTE0, UARTE0_UART0);
 
 impl_spim!(SPI0, SPIM0, SPIM0_SPIS0_SPI0);
 
+impl_twim!(TWI0, TWIM0, TWIM0_TWIS0_TWI0);
+
 impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
diff --git a/embassy-nrf/src/chips/nrf52811.rs b/embassy-nrf/src/chips/nrf52811.rs
index e3f4f18ba..6728f6a41 100644
--- a/embassy-nrf/src/chips/nrf52811.rs
+++ b/embassy-nrf/src/chips/nrf52811.rs
@@ -115,6 +115,8 @@ impl_uarte!(UARTE0, UARTE0, UARTE0_UART0);
 impl_spim!(TWISPI0, SPIM0, TWIM0_TWIS0_TWI0_SPIM0_SPIS0_SPI0);
 impl_spim!(SPI1, SPIM1, SPIM1_SPIS1_SPI1);
 
+impl_twim!(TWISPI0, TWIM0, TWIM0_TWIS0_TWI0_SPIM0_SPIS0_SPI0);
+
 impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
diff --git a/embassy-nrf/src/chips/nrf52820.rs b/embassy-nrf/src/chips/nrf52820.rs
index e367a7916..2f9eb5f53 100644
--- a/embassy-nrf/src/chips/nrf52820.rs
+++ b/embassy-nrf/src/chips/nrf52820.rs
@@ -116,6 +116,9 @@ impl_uarte!(UARTE0, UARTE0, UARTE0_UART0);
 impl_spim!(TWISPI0, SPIM0, SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0);
 impl_spim!(TWISPI1, SPIM1, SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1);
 
+impl_twim!(TWISPI0, TWIM0, SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0);
+impl_twim!(TWISPI1, TWIM1, SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1);
+
 impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
diff --git a/embassy-nrf/src/chips/nrf52832.rs b/embassy-nrf/src/chips/nrf52832.rs
index e0669d93e..015bc51f8 100644
--- a/embassy-nrf/src/chips/nrf52832.rs
+++ b/embassy-nrf/src/chips/nrf52832.rs
@@ -121,6 +121,9 @@ impl_spim!(TWISPI0, SPIM0, SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0);
 impl_spim!(TWISPI1, SPIM1, SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1);
 impl_spim!(SPI2, SPIM2, SPIM2_SPIS2_SPI2);
 
+impl_twim!(TWISPI0, TWIM0, SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0);
+impl_twim!(TWISPI1, TWIM1, SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1);
+
 impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
diff --git a/embassy-nrf/src/chips/nrf52833.rs b/embassy-nrf/src/chips/nrf52833.rs
index a0b434229..404883934 100644
--- a/embassy-nrf/src/chips/nrf52833.rs
+++ b/embassy-nrf/src/chips/nrf52833.rs
@@ -142,6 +142,9 @@ impl_spim!(TWISPI1, SPIM1, SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1);
 impl_spim!(SPI2, SPIM2, SPIM2_SPIS2_SPI2);
 impl_spim!(SPI3, SPIM3, SPIM3);
 
+impl_twim!(TWISPI0, TWIM0, SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0);
+impl_twim!(TWISPI1, TWIM1, SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1);
+
 impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
diff --git a/embassy-nrf/src/chips/nrf52840.rs b/embassy-nrf/src/chips/nrf52840.rs
index 9a9f99201..26dfc7e8f 100644
--- a/embassy-nrf/src/chips/nrf52840.rs
+++ b/embassy-nrf/src/chips/nrf52840.rs
@@ -145,6 +145,9 @@ impl_spim!(TWISPI1, SPIM1, SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1);
 impl_spim!(SPI2, SPIM2, SPIM2_SPIS2_SPI2);
 impl_spim!(SPI3, SPIM3, SPIM3);
 
+impl_twim!(TWISPI0, TWIM0, SPIM0_SPIS0_TWIM0_TWIS0_SPI0_TWI0);
+impl_twim!(TWISPI1, TWIM1, SPIM1_SPIS1_TWIM1_TWIS1_SPI1_TWI1);
+
 impl_timer!(TIMER0, TIMER0, TIMER0);
 impl_timer!(TIMER1, TIMER1, TIMER1);
 impl_timer!(TIMER2, TIMER2, TIMER2);
diff --git a/embassy-nrf/src/lib.rs b/embassy-nrf/src/lib.rs
index 066bf5f6f..2b35fdd6a 100644
--- a/embassy-nrf/src/lib.rs
+++ b/embassy-nrf/src/lib.rs
@@ -37,6 +37,7 @@ pub mod saadc;
 pub mod spim;
 pub mod system;
 pub mod timer;
+pub mod twim;
 pub mod uarte;
 
 // This mod MUST go last, so that it sees all the `impl_foo!` macros
diff --git a/embassy-nrf/src/twim.rs b/embassy-nrf/src/twim.rs
new file mode 100644
index 000000000..cbaf97dff
--- /dev/null
+++ b/embassy-nrf/src/twim.rs
@@ -0,0 +1,531 @@
+#![macro_use]
+
+//! HAL interface to the TWIM peripheral.
+//!
+//! See product specification:
+//!
+//! - nRF52832: Section 33
+//! - nRF52840: Section 6.31
+use core::marker::PhantomData;
+use core::sync::atomic::{compiler_fence, Ordering::SeqCst};
+use embassy::interrupt::{Interrupt, InterruptExt};
+use embassy::util::{AtomicWaker, Unborrow};
+use embassy_extras::unborrow;
+
+use crate::chip::{EASY_DMA_SIZE, FORCE_COPY_BUFFER_SIZE};
+use crate::fmt::*;
+use crate::gpio::Pin as GpioPin;
+use crate::pac;
+use crate::util::{slice_in_ram, slice_in_ram_or};
+
+pub enum Frequency {
+    #[doc = "26738688: 100 kbps"]
+    K100 = 26738688,
+    #[doc = "67108864: 250 kbps"]
+    K250 = 67108864,
+    #[doc = "104857600: 400 kbps"]
+    K400 = 104857600,
+}
+
+#[non_exhaustive]
+pub struct Config {
+    pub frequency: Frequency,
+}
+
+impl Default for Config {
+    fn default() -> Self {
+        Self {
+            frequency: Frequency::K100,
+        }
+    }
+}
+
+/// Interface to a TWIM instance.
+pub struct Twim<'d, T: Instance> {
+    peri: T,
+    irq: T::Interrupt,
+    phantom: PhantomData<&'d mut T>,
+}
+
+impl<'d, T: Instance> Twim<'d, T> {
+    pub fn new(
+        twim: impl Unborrow<Target = T> + 'd,
+        irq: impl Unborrow<Target = T::Interrupt> + 'd,
+        sda: impl Unborrow<Target = impl GpioPin> + 'd,
+        scl: impl Unborrow<Target = impl GpioPin> + 'd,
+        config: Config,
+    ) -> Self {
+        unborrow!(twim, irq, sda, scl);
+
+        let r = T::regs();
+
+        // Configure pins
+        sda.conf().write(|w| {
+            w.dir().input();
+            w.input().connect();
+            w.pull().pullup();
+            w.drive().s0d1();
+            w
+        });
+        scl.conf().write(|w| {
+            w.dir().input();
+            w.input().connect();
+            w.pull().pullup();
+            w.drive().s0d1();
+            w
+        });
+
+        // Select pins.
+        r.psel.sda.write(|w| unsafe { w.bits(sda.psel_bits()) });
+        r.psel.scl.write(|w| unsafe { w.bits(scl.psel_bits()) });
+
+        // Enable TWIM instance.
+        r.enable.write(|w| w.enable().enabled());
+
+        // Configure frequency.
+        r.frequency
+            .write(|w| unsafe { w.frequency().bits(config.frequency as u32) });
+
+        // Disable all events interrupts
+        r.intenclr.write(|w| unsafe { w.bits(0xFFFF_FFFF) });
+
+        irq.set_handler(Self::on_interrupt);
+        irq.unpend();
+        irq.enable();
+
+        Self {
+            peri: twim,
+            irq,
+            phantom: PhantomData,
+        }
+    }
+
+    fn on_interrupt(_: *mut ()) {
+        let r = T::regs();
+        let s = T::state();
+
+        if r.events_stopped.read().bits() != 0 {
+            s.end_waker.wake();
+            r.intenclr.write(|w| w.stopped().clear());
+        }
+        if r.events_error.read().bits() != 0 {
+            s.end_waker.wake();
+            r.intenclr.write(|w| w.error().clear());
+        }
+    }
+
+    /// Set TX buffer, checking that it is in RAM and has suitable length.
+    unsafe fn set_tx_buffer(&mut self, buffer: &[u8]) -> Result<(), Error> {
+        slice_in_ram_or(buffer, Error::DMABufferNotInDataMemory)?;
+
+        if buffer.len() == 0 {
+            return Err(Error::TxBufferZeroLength);
+        }
+        if buffer.len() > EASY_DMA_SIZE {
+            return Err(Error::TxBufferTooLong);
+        }
+
+        let r = T::regs();
+
+        r.txd.ptr.write(|w|
+            // We're giving the register a pointer to the stack. Since we're
+            // waiting for the I2C transaction to end before this stack pointer
+            // becomes invalid, there's nothing wrong here.
+            //
+            // The PTR field is a full 32 bits wide and accepts the full range
+            // of values.
+            w.ptr().bits(buffer.as_ptr() as u32));
+        r.txd.maxcnt.write(|w|
+            // We're giving it the length of the buffer, so no danger of
+            // accessing invalid memory. We have verified that the length of the
+            // buffer fits in an `u8`, so the cast to `u8` is also fine.
+            //
+            // The MAXCNT field is 8 bits wide and accepts the full range of
+            // values.
+            w.maxcnt().bits(buffer.len() as _));
+
+        Ok(())
+    }
+
+    /// Set RX buffer, checking that it has suitable length.
+    unsafe fn set_rx_buffer(&mut self, buffer: &mut [u8]) -> Result<(), Error> {
+        // NOTE: RAM slice check is not necessary, as a mutable
+        // slice can only be built from data located in RAM.
+
+        if buffer.len() == 0 {
+            return Err(Error::RxBufferZeroLength);
+        }
+        if buffer.len() > EASY_DMA_SIZE {
+            return Err(Error::RxBufferTooLong);
+        }
+
+        let r = T::regs();
+
+        r.rxd.ptr.write(|w|
+            // We're giving the register a pointer to the stack. Since we're
+            // waiting for the I2C transaction to end before this stack pointer
+            // becomes invalid, there's nothing wrong here.
+            //
+            // The PTR field is a full 32 bits wide and accepts the full range
+            // of values.
+            w.ptr().bits(buffer.as_mut_ptr() as u32));
+        r.rxd.maxcnt.write(|w|
+            // We're giving it the length of the buffer, so no danger of
+            // accessing invalid memory. We have verified that the length of the
+            // buffer fits in an `u8`, so the cast to the type of maxcnt
+            // is also fine.
+            //
+            // Note that that nrf52840 maxcnt is a wider
+            // type than a u8, so we use a `_` cast rather than a `u8` cast.
+            // The MAXCNT field is thus at least 8 bits wide and accepts the
+            // full range of values that fit in a `u8`.
+            w.maxcnt().bits(buffer.len() as _));
+
+        Ok(())
+    }
+
+    fn clear_errorsrc(&mut self) {
+        let r = T::regs();
+        r.errorsrc
+            .write(|w| w.anack().bit(true).dnack().bit(true).overrun().bit(true));
+    }
+
+    /// Get Error instance, if any occurred.
+    fn read_errorsrc(&self) -> Result<(), Error> {
+        let r = T::regs();
+
+        let err = r.errorsrc.read();
+        if err.anack().is_received() {
+            return Err(Error::AddressNack);
+        }
+        if err.dnack().is_received() {
+            return Err(Error::DataNack);
+        }
+        if err.overrun().is_received() {
+            return Err(Error::DataNack);
+        }
+        Ok(())
+    }
+
+    /// Wait for stop or error
+    fn wait(&mut self) {
+        let r = T::regs();
+        loop {
+            if r.events_stopped.read().bits() != 0 {
+                r.events_stopped.reset();
+                break;
+            }
+            if r.events_error.read().bits() != 0 {
+                r.events_error.reset();
+                r.tasks_stop.write(|w| unsafe { w.bits(1) });
+            }
+        }
+    }
+
+    /// Write to an I2C slave.
+    ///
+    /// The buffer must have a length of at most 255 bytes on the nRF52832
+    /// and at most 65535 bytes on the nRF52840.
+    pub fn write(&mut self, address: u8, buffer: &[u8]) -> Result<(), Error> {
+        let r = T::regs();
+
+        // Conservative compiler fence to prevent optimizations that do not
+        // take in to account actions by DMA. The fence has been placed here,
+        // before any DMA action has started.
+        compiler_fence(SeqCst);
+
+        r.address.write(|w| unsafe { w.address().bits(address) });
+
+        // Set up the DMA write.
+        unsafe { self.set_tx_buffer(buffer)? };
+
+        // Clear events
+        r.events_stopped.reset();
+        r.events_error.reset();
+        r.events_lasttx.reset();
+        self.clear_errorsrc();
+
+        // Start write operation.
+        r.shorts.write(|w| w.lasttx_stop().enabled());
+        r.tasks_starttx.write(|w|
+            // `1` is a valid value to write to task registers.
+            unsafe { w.bits(1) });
+
+        self.wait();
+
+        // Conservative compiler fence to prevent optimizations that do not
+        // take in to account actions by DMA. The fence has been placed here,
+        // after all possible DMA actions have completed.
+        compiler_fence(SeqCst);
+
+        self.read_errorsrc()?;
+
+        if r.txd.amount.read().bits() != buffer.len() as u32 {
+            return Err(Error::Transmit);
+        }
+
+        Ok(())
+    }
+
+    /// Read from an I2C slave.
+    ///
+    /// The buffer must have a length of at most 255 bytes on the nRF52832
+    /// and at most 65535 bytes on the nRF52840.
+    pub fn read(&mut self, address: u8, buffer: &mut [u8]) -> Result<(), Error> {
+        let r = T::regs();
+
+        // Conservative compiler fence to prevent optimizations that do not
+        // take in to account actions by DMA. The fence has been placed here,
+        // before any DMA action has started.
+        compiler_fence(SeqCst);
+
+        r.address.write(|w| unsafe { w.address().bits(address) });
+
+        // Set up the DMA read.
+        unsafe { self.set_rx_buffer(buffer)? };
+
+        // Clear events
+        r.events_stopped.reset();
+        r.events_error.reset();
+        self.clear_errorsrc();
+
+        // Start read operation.
+        r.shorts.write(|w| w.lastrx_stop().enabled());
+        r.tasks_startrx.write(|w|
+            // `1` is a valid value to write to task registers.
+            unsafe { w.bits(1) });
+
+        self.wait();
+
+        // Conservative compiler fence to prevent optimizations that do not
+        // take in to account actions by DMA. The fence has been placed here,
+        // after all possible DMA actions have completed.
+        compiler_fence(SeqCst);
+
+        self.read_errorsrc()?;
+
+        if r.rxd.amount.read().bits() != buffer.len() as u32 {
+            return Err(Error::Receive);
+        }
+
+        Ok(())
+    }
+
+    /// Write data to an I2C slave, then read data from the slave without
+    /// triggering a stop condition between the two.
+    ///
+    /// The buffers must have a length of at most 255 bytes on the nRF52832
+    /// and at most 65535 bytes on the nRF52840.
+    pub fn write_then_read(
+        &mut self,
+        address: u8,
+        wr_buffer: &[u8],
+        rd_buffer: &mut [u8],
+    ) -> Result<(), Error> {
+        let r = T::regs();
+
+        // Conservative compiler fence to prevent optimizations that do not
+        // take in to account actions by DMA. The fence has been placed here,
+        // before any DMA action has started.
+        compiler_fence(SeqCst);
+
+        r.address.write(|w| unsafe { w.address().bits(address) });
+
+        // Set up DMA buffers.
+        unsafe {
+            self.set_tx_buffer(wr_buffer)?;
+            self.set_rx_buffer(rd_buffer)?;
+        }
+
+        // Clear events
+        r.events_stopped.reset();
+        r.events_error.reset();
+        self.clear_errorsrc();
+
+        // Start write+read operation.
+        r.shorts.write(|w| {
+            w.lasttx_startrx().enabled();
+            w.lastrx_stop().enabled();
+            w
+        });
+        // `1` is a valid value to write to task registers.
+        r.tasks_starttx.write(|w| unsafe { w.bits(1) });
+
+        self.wait();
+
+        // Conservative compiler fence to prevent optimizations that do not
+        // take in to account actions by DMA. The fence has been placed here,
+        // after all possible DMA actions have completed.
+        compiler_fence(SeqCst);
+
+        self.read_errorsrc()?;
+
+        let bad_write = r.txd.amount.read().bits() != wr_buffer.len() as u32;
+        let bad_read = r.rxd.amount.read().bits() != rd_buffer.len() as u32;
+
+        if bad_write {
+            return Err(Error::Transmit);
+        }
+
+        if bad_read {
+            return Err(Error::Receive);
+        }
+
+        Ok(())
+    }
+
+    /// Copy data into RAM and write to an I2C slave.
+    ///
+    /// The write buffer must have a length of at most 255 bytes on the nRF52832
+    /// and at most 1024 bytes on the nRF52840.
+    pub fn copy_write(&mut self, address: u8, wr_buffer: &[u8]) -> Result<(), Error> {
+        if wr_buffer.len() > FORCE_COPY_BUFFER_SIZE {
+            return Err(Error::TxBufferTooLong);
+        }
+
+        // Copy to RAM
+        let wr_ram_buffer = &mut [0; FORCE_COPY_BUFFER_SIZE][..wr_buffer.len()];
+        wr_ram_buffer.copy_from_slice(wr_buffer);
+
+        self.write(address, wr_ram_buffer)
+    }
+
+    /// Copy data into RAM and write to an I2C slave, then read data from the slave without
+    /// triggering a stop condition between the two.
+    ///
+    /// The write buffer must have a length of at most 255 bytes on the nRF52832
+    /// and at most 1024 bytes on the nRF52840.
+    ///
+    /// The read buffer must have a length of at most 255 bytes on the nRF52832
+    /// and at most 65535 bytes on the nRF52840.
+    pub fn copy_write_then_read(
+        &mut self,
+        address: u8,
+        wr_buffer: &[u8],
+        rd_buffer: &mut [u8],
+    ) -> Result<(), Error> {
+        if wr_buffer.len() > FORCE_COPY_BUFFER_SIZE {
+            return Err(Error::TxBufferTooLong);
+        }
+
+        // Copy to RAM
+        let wr_ram_buffer = &mut [0; FORCE_COPY_BUFFER_SIZE][..wr_buffer.len()];
+        wr_ram_buffer.copy_from_slice(wr_buffer);
+
+        self.write_then_read(address, wr_ram_buffer, rd_buffer)
+    }
+}
+
+impl<'a, T: Instance> Drop for Twim<'a, T> {
+    fn drop(&mut self) {
+        info!("twim drop");
+
+        // TODO when implementing async here, check for abort
+
+        // disable!
+        let r = T::regs();
+        r.enable.write(|w| w.enable().disabled());
+
+        info!("uarte drop: done");
+
+        // TODO: disable pins
+    }
+}
+
+impl<'a, T: Instance> embedded_hal::blocking::i2c::Write for Twim<'a, T> {
+    type Error = Error;
+
+    fn write<'w>(&mut self, addr: u8, bytes: &'w [u8]) -> Result<(), Error> {
+        if slice_in_ram(bytes) {
+            self.write(addr, bytes)
+        } else {
+            let buf = &mut [0; FORCE_COPY_BUFFER_SIZE][..];
+            for chunk in bytes.chunks(FORCE_COPY_BUFFER_SIZE) {
+                buf[..chunk.len()].copy_from_slice(chunk);
+                self.write(addr, &buf[..chunk.len()])?;
+            }
+            Ok(())
+        }
+    }
+}
+
+impl<'a, T: Instance> embedded_hal::blocking::i2c::Read for Twim<'a, T> {
+    type Error = Error;
+
+    fn read<'w>(&mut self, addr: u8, bytes: &'w mut [u8]) -> Result<(), Error> {
+        self.read(addr, bytes)
+    }
+}
+
+impl<'a, T: Instance> embedded_hal::blocking::i2c::WriteRead for Twim<'a, T> {
+    type Error = Error;
+
+    fn write_read<'w>(
+        &mut self,
+        addr: u8,
+        bytes: &'w [u8],
+        buffer: &'w mut [u8],
+    ) -> Result<(), Error> {
+        if slice_in_ram(bytes) {
+            self.write_then_read(addr, bytes, buffer)
+        } else {
+            self.copy_write_then_read(addr, bytes, buffer)
+        }
+    }
+}
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub enum Error {
+    TxBufferTooLong,
+    RxBufferTooLong,
+    TxBufferZeroLength,
+    RxBufferZeroLength,
+    Transmit,
+    Receive,
+    DMABufferNotInDataMemory,
+    AddressNack,
+    DataNack,
+    Overrun,
+}
+
+pub(crate) mod sealed {
+    use super::*;
+
+    pub struct State {
+        pub end_waker: AtomicWaker,
+    }
+
+    impl State {
+        pub const fn new() -> Self {
+            Self {
+                end_waker: AtomicWaker::new(),
+            }
+        }
+    }
+
+    pub trait Instance {
+        fn regs() -> &'static pac::twim0::RegisterBlock;
+        fn state() -> &'static State;
+    }
+}
+
+pub trait Instance: sealed::Instance + 'static {
+    type Interrupt: Interrupt;
+}
+
+macro_rules! impl_twim {
+    ($type:ident, $pac_type:ident, $irq:ident) => {
+        impl crate::twim::sealed::Instance for peripherals::$type {
+            fn regs() -> &'static pac::twim0::RegisterBlock {
+                unsafe { &*pac::$pac_type::ptr() }
+            }
+            fn state() -> &'static crate::twim::sealed::State {
+                static STATE: crate::twim::sealed::State = crate::twim::sealed::State::new();
+                &STATE
+            }
+        }
+        impl crate::twim::Instance for peripherals::$type {
+            type Interrupt = crate::interrupt::$irq;
+        }
+    };
+}