Initial rp2040 support.

Cargo.toml

@@ -28,6 +28,7 @@ members = [
     "app/demo-stm32f4-discovery",
     "app/demo-stm32g0-nucleo",
     "app/demo-stm32h7-nucleo",
+    "app/demo-pi-pico",
     "app/gemini-bu",
     "app/gemini-bu-rot",
     "app/gimlet",
@@ -93,6 +94,9 @@ members = [
     "drv/lpc55-rng",
     "drv/lpc55-swd",
 
+    "drv/rp2040-sys-api",
+    "drv/rp2040-sys",
+
     "drv/user-leds",
     "drv/user-leds-api",
     "drv/ice40-spi-program",

app/demo-pi-pico/.gitignore

@@ -0,0 +1,12 @@
+**/*.rs.bk
+.#*
+.gdb_history
+target/
+
+# editor files
+.vscode/*
+!.vscode/*.md
+!.vscode/*.svd
+!.vscode/launch.json
+!.vscode/tasks.json
+!.vscode/extensions.json

app/demo-pi-pico/Cargo.toml

@@ -0,0 +1,31 @@
+[package]
+edition = "2018"
+readme = "README.md"
+name = "demo-pi-pico"
+version = "0.1.0"
+
+[features]
+semihosting = ["panic-semihosting", "klog-semihosting"]
+klog-semihosting = ["kern/klog-semihosting"]
+
+[dependencies]
+cortex-m = { version = "0.7", features = ["inline-asm"] }
+cortex-m-rt = "0.6.12"
+panic-halt = { version = "0.2.0", optional = true }
+panic-semihosting = { version = "0.5.3", optional = true }
+cfg-if = "0.1.10"
+rp2040-pac = {version = "0.3", features = ["rt"]}
+rp2040-boot2 = "0.2"
+
+[dependencies.kern]
+path = "../../sys/kern"
+default-features = false
+
+[build-dependencies]
+build-util = {path = "../../build/util"}
+
+# this lets you use `cargo fix`!
+[[bin]]
+name = "demo-pi-pico"
+test = false
+bench = false

app/demo-pi-pico/README.md

@@ -0,0 +1,52 @@
+# Rasperry Pi Pico demo application
+
+This will blink an LED, and not a whole lot else, on a Raspberry Pi Pico board
+(based on the RP2040).
+
+Currently, our tools don't know how to flash this board. So, to use this, you'll
+have to jump through some hoops.
+
+You will need:
+
+- [uf2l](https://github.com/cbiffle/uf2l) - you can install it, or run it from
+  the build directory, but the instructions below will just refer to it as
+  `uf2l`.
+- [rp2040-rustboot](https://github.com/cbiffle/rp2040-rustboot) - run the
+  `build-all.sh` to produce ELF binaries. The instructions below will refer to
+  its location as `$RUSTBOOT`.
+
+To build and prepare the image:
+
+```
+cargo xtask dist app/demo-pi-pico/app.toml
+uf2l pack -e 4096 \
+          $RUSTBOOT/elf/rustboot-w25q080 \
+          target/demo-pi-pico/dist/combined.elf \
+          hubris-pico.uf2
+```
+
+Then, hold BOOTSEL while plugging in your Pi Pico. It should show up as a USB
+drive. Copy the `hubris-pico.uf2` file onto it. It should reboot and begin
+blinking a light at 1 Hz.
+
+## Debugging
+
+General RP2040 support in OpenOCD hasn't been upstreamed, but amusingly there
+_is_ upstream support for the [pico-debug] same-chip debugger. This will run on
+core 1 while Hubris runs on core 0.
+
+To use this:
+
+1. Flash Hubris as described above.
+2. Ensure that you've got a fairly recent OpenOCD git build.
+3. Download the GIMMECACHE version of the debug image.
+4. Hold BOOTSEL and reboot your RP2040 board into the bootloader.
+5. Copy the GIMMECACHE UF2 image onto the board. It should reboot. It does not
+   appear to correctly start the Flash image by default, but that's easy to fix:
+6. From this directory, run: `openocd -f openocd-pico-debug.cfg -c init -c reset
+   -c exit`
+
+The clock configuration under pico-debug is slightly different from the reset
+configuration; there is code in `src/main.rs` to adjust for this. It is a hack.
+
+[pico-debug]: https://github.com/majbthrd/pico-debug

app/demo-pi-pico/app.toml

@@ -0,0 +1,89 @@
+name = "demo-pi-pico"
+target = "thumbv6m-none-eabi"
+chip = "../../chips/rp2040.toml"
+board = "pi-pico"
+stacksize = 944
+
+[kernel]
+path = "."
+name = "demo-pi-pico"
+requires = {flash = 12000, ram = 1696}
+features = ["panic-halt"]
+stacksize = 640
+
+[supervisor]
+notification = 1
+
+[outputs.flash]
+address = 0x10000100  # just past the bootloader
+size = 0x1fff00  # 2MiB - 256 bytes
+read = true
+execute = true
+
+[outputs.ram]
+address = 0x20000000
+size = 270336
+read = true
+write = true
+execute = false  # let's assume XN until proven otherwise
+
+[tasks.jefe]
+path = "../../task/jefe"
+name = "task-jefe"
+priority = 0
+requires = {flash = 4096, ram = 512}
+start = true
+features = ["log-null"]
+stacksize = 352
+
+[tasks.sys]
+path = "../../drv/rp2040-sys"
+name = "drv-rp2040-sys"
+priority = 1
+requires = {flash = 1024, ram = 256}
+uses = ["resets", "sio"]
+start = true
+stacksize = 256
+
+[tasks.user_leds]
+path = "../../drv/user-leds"
+name = "drv-user-leds"
+features = ["rp2040"]
+priority = 2
+requires = {flash = 1024, ram = 256}
+start = true
+task-slots = ["sys"]
+stacksize = 256
+
+[tasks.pong]
+path = "../../task/pong"
+name = "task-pong"
+priority = 3
+requires = {flash = 1024, ram = 256}
+start = true
+task-slots = ["user_leds"]
+stacksize = 256
+
+[tasks.ping]
+path = "../../task/ping"
+name = "task-ping"
+priority = 4
+requires = {flash = 4096, ram = 512}
+stacksize = 256
+start = true
+task-slots = [{peer = "pong"}]
+
+[tasks.hiffy]
+path = "../../task/hiffy"
+name = "task-hiffy"
+priority = 3
+requires = {flash = 8192, ram = 8192 }
+start = true
+
+[tasks.idle]
+path = "../../task/idle"
+name = "task-idle"
+priority = 5
+requires = {flash = 128, ram = 64}
+stacksize = 64
+start = true

app/demo-pi-pico/build.rs

@@ -0,0 +1,7 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+fn main() {
+    build_util::expose_target_board();
+}

app/demo-pi-pico/openocd-pico-debug.cfg

@@ -0,0 +1,6 @@
+source [find interface/cmsis-dap.cfg]
+source [find target/rp2040-core0.cfg]
+
+transport select swd
+
+adapter_khz 500

app/demo-pi-pico/src/main.rs

@@ -0,0 +1,57 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+#![no_std]
+#![no_main]
+
+#[cfg(not(any(
+    feature = "panic-itm",
+    feature = "panic-semihosting",
+    feature = "panic-halt"
+)))]
+compile_error!("Must have one of panic-{itm,semihosting,halt} enabled");
+
+// Panic behavior controlled by Cargo features:
+#[cfg(feature = "panic-halt")]
+extern crate panic_halt;
+#[cfg(feature = "panic-itm")]
+extern crate panic_itm; // breakpoint on `rust_begin_unwind` to catch panics
+#[cfg(feature = "panic-semihosting")]
+extern crate panic_semihosting; // requires a debugger
+
+// We have to do this if we don't otherwise use it to ensure its vector table
+// gets linked in.
+use rp2040_pac as _;
+
+#[link_section = ".boot_loader"]
+#[used]
+pub static BOOT_LOADER: [u8; 256] = rp2040_boot2::BOOT_LOADER_W25Q080;
+
+use cortex_m_rt::entry;
+
+#[entry]
+fn main() -> ! {
+    let p = unsafe { rp2040_pac::Peripherals::steal() };
+
+    p.RESETS.reset.modify(|_, w| w.io_bank0().clear_bit());
+    while !p.RESETS.reset_done.read().io_bank0().bit() {}
+
+    p.SIO.gpio_oe_set.write(|w| unsafe { w.bits(1 << 25) });
+    p.SIO.gpio_out_set.write(|w| unsafe { w.bits(1 << 25) });
+
+    p.IO_BANK0.gpio[25].gpio_ctrl.write(|w| w.funcsel().sio());
+
+    let cycles_per_ms = if p.CLOCKS.clk_sys_ctrl.read().src().is_clk_ref() {
+        // This is the reset state, so we'll assume we launched directly from
+        // flash running on the ROSC.
+        6_000 // ish
+    } else {
+        // This is _not_ the reset state, so we'll assume that the pico-debug
+        // resident debugger has reconfigured things to run off the 48 MHz USB
+        // clock.
+        48_000
+    };
+
+    unsafe { kern::startup::start_kernel(cycles_per_ms) }
+}

build/xtask/src/dist.rs

@@ -639,10 +639,10 @@ Did you mean to run `cargo xtask dist`?"
     // any external configuration files, serialize it, and add it to the
     // archive.
     //
-    let mut config = crate::flash::config(&toml.board.as_str())?;
-    config.flatten()?;
-
-    archive.text(img_dir.join("flash.ron"), ron::to_string(&config)?)?;
+    if let Some(mut config) = crate::flash::config(&toml.board.as_str())? {
+        config.flatten()?;
+        archive.text(img_dir.join("flash.ron"), ron::to_string(&config)?)?;
+    }
 
     archive.finish()?;