boards: add makepython-nrf52840

Cargo.toml

@@ -28,6 +28,7 @@ members = [
     "boards/msp_exp432p401r",
     "boards/microbit_v2",
     "boards/wm1110dev",
+    "boards/makepython-nrf52840",
     "boards/nordic/nrf52840dk",
     "boards/nordic/nrf52840_dongle",
     "boards/nordic/nrf52dk",

boards/makepython-nrf52840/Cargo.toml

@@ -0,0 +1,21 @@
+# Licensed under the Apache License, Version 2.0 or the MIT License.
+# SPDX-License-Identifier: Apache-2.0 OR MIT
+# Copyright Tock Contributors 2022.
+
+[package]
+name = "makepython-nrf52840"
+version.workspace = true
+authors.workspace = true
+build = "build.rs"
+edition.workspace = true
+
+[dependencies]
+cortexm4 = { path = "../../arch/cortex-m4" }
+kernel = { path = "../../kernel" }
+nrf52 = { path = "../../chips/nrf52" }
+nrf52840 = { path = "../../chips/nrf52840" }
+components = { path = "../components" }
+nrf52_components = { path = "../nordic/nrf52_components" }
+
+capsules-core = { path = "../../capsules/core" }
+capsules-extra = { path = "../../capsules/extra" }

boards/makepython-nrf52840/Makefile

@@ -0,0 +1,30 @@
+# Licensed under the Apache License, Version 2.0 or the MIT License.
+# SPDX-License-Identifier: Apache-2.0 OR MIT
+# Copyright Tock Contributors 2022.
+
+# Makefile for building the tock kernel for the Arduino Nano 33 BLE board.
+
+TOCK_ARCH=cortex-m4
+TARGET=thumbv7em-none-eabi
+PLATFORM=makepython-nrf52840
+
+include ../Makefile.common
+
+ifdef PORT
+  FLAGS += --port $(PORT)
+endif
+
+# Default target for installing the kernel.
+.PHONY: install
+install: program
+
+# Upload the kernel using tockloader and the tock bootloader
+.PHONY: program
+program: $(TOCK_ROOT_DIRECTORY)target/$(TARGET)/release/$(PLATFORM).bin
+	tockloader $(FLAGS) flash --address 0x10000 $<
+
+.PHONY: flash-bootloader
+flash-bootloader:
+	curl -L --output /tmp/makepython-nrf52840-bootloader_v1.1.3.bin https://github.com/tock/tock-bootloader/releases/download/v1.1.3/makepython-nrf52840-bootloader_v1.1.3.bin
+	tockloader flash --address 0 /tmp/makepython-nrf52840-bootloader_v1.1.3.bin
+	rm /tmp/makepython-nrf52840-bootloader_v1.1.3.bin

boards/makepython-nrf52840/README.md

@@ -0,0 +1,52 @@
+MakePython nRF52840
+===================
+
+<img src="https://www.makerfabs.com/image/cache/makerfabs/MakePython%20nRF52840/MakePython%20nRF52840-1-1000x750.jpg" width="35%">
+
+The [MakePython nRF52840](https://www.makerfabs.com/makepython-nrf52840.html) is
+a development board with the Nordic nRF52840 SoC and a 128 x 64 pixel OLED
+display.
+
+
+## Getting Started
+
+First, follow the [Tock Getting Started guide](../../doc/Getting_Started.md).
+
+The MakePython nRF52840 is designed to be programmed using an external JLink
+programmer. We would like to avoid this requirement, so we use the [Tock
+Bootloader](https://github.com/tock/tock-bootloader) which allows us to program
+the board over the UART connection. However, we still require the programmer one
+time to flash the bootloader.
+
+To flash the bootloader we must connect a JLink programmer. The easiest way is
+to use an nRF52840dk board.
+
+### Connect the nRF52840dk to the MakePython-nRF52840
+
+First we jumper the board as shown with the following pin mappings
+
+| nRF52840dk | MakePython-nRF52840 |
+|------------|---------------------|
+| GND        | GND                 |
+| SWD SEL    | +3V3                |
+| SWD CLK    | SWDCLK              |
+| SWD IO     | SWDDIO              |
+
+Make sure _both_ the nRF52840dk board and the MakePython-nRF52840 board are
+attached to your computer via two USB connections.
+
+Then:
+
+```
+make flash-bootloader
+```
+
+This will use JLinkExe to flash the bootloader using the nRF52840dk's onboard
+jtag hardware.
+
+### Using the Bootloader
+
+The bootloader activates when the reset button is pressed twice in quick
+succession. The green LED will stay on when the bootloader is active.
+
+Once the bootloader is installed tockloader will work as expected.

boards/makepython-nrf52840/build.rs

@@ -0,0 +1,8 @@
+// Licensed under the Apache License, Version 2.0 or the MIT License.
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+// Copyright Tock Contributors 2022.
+
+fn main() {
+    println!("cargo:rerun-if-changed=layout.ld");
+    println!("cargo:rerun-if-changed=../kernel_layout.ld");
+}

boards/makepython-nrf52840/layout.ld

@@ -0,0 +1,14 @@
+/* Licensed under the Apache License, Version 2.0 or the MIT License. */
+/* SPDX-License-Identifier: Apache-2.0 OR MIT                         */
+/* Copyright Tock Contributors 2023.                                  */
+
+MEMORY
+{
+  rom (rx)  : ORIGIN = 0x00010000, LENGTH = 256K
+  prog (rx) : ORIGIN = 0x00050000, LENGTH = 704K
+  ram (rwx) : ORIGIN = 0x20000000, LENGTH = 256K
+}
+
+PAGE_SIZE = 4K;
+
+INCLUDE ../kernel_layout.ld

boards/makepython-nrf52840/src/io.rs

@@ -0,0 +1,144 @@
+// Licensed under the Apache License, Version 2.0 or the MIT License.
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+// Copyright Tock Contributors 2022.
+
+use core::fmt::Write;
+use core::panic::PanicInfo;
+
+use cortexm4;
+use kernel::debug;
+use kernel::debug::IoWrite;
+use kernel::hil::led;
+use kernel::hil::uart::{self};
+use kernel::ErrorCode;
+use nrf52840::gpio::Pin;
+
+use crate::CHIP;
+use crate::PROCESSES;
+use crate::PROCESS_PRINTER;
+use kernel::hil::uart::Transmit;
+use kernel::utilities::cells::VolatileCell;
+
+struct Writer {
+    initialized: bool,
+}
+
+static mut WRITER: Writer = Writer { initialized: false };
+
+impl Write for Writer {
+    fn write_str(&mut self, s: &str) -> ::core::fmt::Result {
+        self.write(s.as_bytes());
+        Ok(())
+    }
+}
+
+const BUF_LEN: usize = 512;
+static mut STATIC_PANIC_BUF: [u8; BUF_LEN] = [0; BUF_LEN];
+
+static mut DUMMY: DummyUsbClient = DummyUsbClient {
+    fired: VolatileCell::new(false),
+};
+
+struct DummyUsbClient {
+    fired: VolatileCell<bool>,
+}
+
+impl uart::TransmitClient for DummyUsbClient {
+    fn transmitted_buffer(&self, _: &'static mut [u8], _: usize, _: Result<(), ErrorCode>) {
+        self.fired.set(true);
+    }
+}
+
+impl IoWrite for Writer {
+    fn write(&mut self, buf: &[u8]) -> usize {
+        if !self.initialized {
+            self.initialized = true;
+        }
+        // Here we mimic a synchronous UART output by calling transmit_buffer
+        // on the CDC stack and then spinning on USB interrupts until the transaction
+        // is complete. If the USB or CDC stack panicked, this may fail. It will also
+        // fail if the panic occurred prior to the USB connection being initialized.
+        // In the latter case, the LEDs should still blink in the panic pattern.
+
+        // spin so that if any USB DMA is ongoing it will finish
+        // we should only need this on the first call to write()
+        let mut i = 0;
+        loop {
+            i += 1;
+            cortexm4::support::nop();
+            if i > 10000 {
+                break;
+            }
+        }
+
+        // copy_from_slice() requires equal length slices
+        // This will truncate any writes longer than BUF_LEN, but simplifies the
+        // code. In practice, BUF_LEN=512 always seems sufficient for the size of
+        // individual calls to write made by the panic handler.
+        let mut max = BUF_LEN;
+        if buf.len() < BUF_LEN {
+            max = buf.len();
+        }
+
+        unsafe {
+            // If CDC_REF_FOR_PANIC is not yet set we panicked very early,
+            // and not much we can do. Don't want to double fault,
+            // so just return.
+            super::CDC_REF_FOR_PANIC.map(|cdc| {
+                // Lots of unsafe dereferencing of global static mut objects here.
+                // However, this should be okay, because it all happens within
+                // a single thread, and:
+                // - This is the only place the global CDC_REF_FOR_PANIC is used, the logic is the same
+                //   as applies for the global CHIP variable used in the panic handler.
+                // - We do create multiple mutable references to the STATIC_PANIC_BUF, but we never
+                //   access the STATIC_PANIC_BUF after a slice of it is passed to transmit_buffer
+                //   until the slice has been returned in the uart callback.
+                // - Similarly, only this function uses the global DUMMY variable, and we do not
+                //   mutate it.
+                let usb = &mut cdc.controller();
+                STATIC_PANIC_BUF[..max].copy_from_slice(&buf[..max]);
+                let static_buf = &mut STATIC_PANIC_BUF;
+                cdc.set_transmit_client(&DUMMY);
+                let _ = cdc.transmit_buffer(static_buf, max);
+                loop {
+                    if let Some(interrupt) = cortexm4::nvic::next_pending() {
+                        if interrupt == 39 {
+                            usb.handle_interrupt();
+                        }
+                        let n = cortexm4::nvic::Nvic::new(interrupt);
+                        n.clear_pending();
+                        n.enable();
+                    }
+                    if DUMMY.fired.get() {
+                        // buffer finished transmitting, return so we can output additional
+                        // messages when requested by the panic handler.
+                        break;
+                    }
+                }
+                DUMMY.fired.set(false);
+            });
+        }
+        buf.len()
+    }
+}
+
+/// Default panic handler for the Nano 33 Board.
+///
+/// We just use the standard default provided by the debug module in the kernel.
+#[cfg(not(test))]
+#[no_mangle]
+#[panic_handler]
+pub unsafe fn panic_fmt(pi: &PanicInfo) -> ! {
+    let led_kernel_pin = &nrf52840::gpio::GPIOPin::new(Pin::P1_10);
+    let led = &mut led::LedLow::new(led_kernel_pin);
+    let writer = &mut WRITER;
+    debug::panic(
+        &mut [led],
+        writer,
+        pi,
+        &cortexm4::support::nop,
+        &PROCESSES,
+        &CHIP,
+        &PROCESS_PRINTER,
+    )
+}