Move bootloader main to examples

This should remove some confusion around embassy-boot-* being a library
vs. a binary. The binary is now an example bootloader instead.

examples/boot/bootloader/stm32/Cargo.toml

@@ -0,0 +1,57 @@
+[package]
+edition = "2021"
+name = "stm32-bootloader-example"
+version = "0.1.0"
+description = "Example bootloader for STM32 chips"
+
+[dependencies]
+defmt = { version = "0.3", optional = true }
+defmt-rtt = { version = "0.3", optional = true }
+
+embassy = { path = "../../../../embassy", default-features = false }
+embassy-stm32 = { path = "../../../../embassy-stm32", default-features = false, features = ["nightly"] }
+embassy-boot-stm32 = { path = "../../../../embassy-boot/stm32", default-features = false }
+cortex-m = { version = "0.7" }
+cortex-m-rt = { version = "0.7" }
+embedded-storage = "0.3.0"
+embedded-storage-async = "0.3.0"
+cfg-if = "1.0.0"
+
+[features]
+defmt = [
+    "dep:defmt",
+    "embassy-boot-stm32/defmt",
+    "embassy-stm32/defmt",
+]
+debug = ["defmt-rtt"]
+
+[profile.dev]
+debug = 2
+debug-assertions = true
+incremental = false
+opt-level = 'z'
+overflow-checks = true
+
+[profile.release]
+codegen-units = 1
+debug = 2
+debug-assertions = false
+incremental = false
+lto = 'fat'
+opt-level = 'z'
+overflow-checks = false
+
+# do not optimize proc-macro crates = faster builds from scratch
+[profile.dev.build-override]
+codegen-units = 8
+debug = false
+debug-assertions = false
+opt-level = 0
+overflow-checks = false
+
+[profile.release.build-override]
+codegen-units = 8
+debug = false
+debug-assertions = false
+opt-level = 0
+overflow-checks = false

examples/boot/bootloader/stm32/README.md

@@ -0,0 +1,11 @@
+# Bootloader for STM32
+
+The bootloader uses `embassy-boot` to interact with the flash.
+
+# Usage
+
+Flash the bootloader
+
+```
+cargo flash --features embassy-stm32/stm32wl55jc-cm4 --release --chip STM32WLE5JCIx
+```

examples/boot/bootloader/stm32/build.rs

@@ -0,0 +1,32 @@
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::PathBuf;
+
+fn main() {
+    // Put `memory.x` in our output directory and ensure it's
+    // on the linker search path.
+    let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    File::create(out.join("memory.x"))
+        .unwrap()
+        .write_all(include_bytes!("memory.x"))
+        .unwrap();
+    println!("cargo:rustc-link-search={}", out.display());
+
+    // By default, Cargo will re-run a build script whenever
+    // any file in the project changes. By specifying `memory.x`
+    // here, we ensure the build script is only re-run when
+    // `memory.x` is changed.
+    println!("cargo:rerun-if-changed=memory.x");
+
+    println!("cargo:rustc-link-arg-bins=--nmagic");
+    println!("cargo:rustc-link-arg-bins=-Tlink.x");
+    if env::var("CARGO_FEATURE_DEFMT").is_ok() {
+        println!("cargo:rustc-link-arg-bins=-Tdefmt.x");
+    }
+
+    let target = env::var("TARGET").unwrap();
+    if target.starts_with("thumbv6m-") {
+        println!("cargo:rustc-cfg=armv6m");
+    }
+}

examples/boot/bootloader/stm32/memory.x

@@ -0,0 +1,18 @@
+MEMORY
+{
+  /* NOTE 1 K = 1 KiBi = 1024 bytes */
+  FLASH                             : ORIGIN = 0x08000000, LENGTH = 24K
+  BOOTLOADER_STATE                  : ORIGIN = 0x08006000, LENGTH = 4K
+  ACTIVE                            : ORIGIN = 0x08008000, LENGTH = 32K
+  DFU                               : ORIGIN = 0x08010000, LENGTH = 36K
+  RAM                         (rwx) : ORIGIN = 0x20000008, LENGTH = 16K
+}
+
+__bootloader_state_start = ORIGIN(BOOTLOADER_STATE) - ORIGIN(FLASH);
+__bootloader_state_end = ORIGIN(BOOTLOADER_STATE) + LENGTH(BOOTLOADER_STATE) - ORIGIN(FLASH);
+
+__bootloader_active_start = ORIGIN(ACTIVE) - ORIGIN(FLASH);
+__bootloader_active_end = ORIGIN(ACTIVE) + LENGTH(ACTIVE) - ORIGIN(FLASH);
+
+__bootloader_dfu_start = ORIGIN(DFU) - ORIGIN(FLASH);
+__bootloader_dfu_end = ORIGIN(DFU) + LENGTH(DFU) - ORIGIN(FLASH);

examples/boot/bootloader/stm32/src/main.rs

@@ -0,0 +1,46 @@
+#![no_std]
+#![no_main]
+
+use cortex_m_rt::{entry, exception};
+#[cfg(feature = "defmt")]
+use defmt_rtt as _;
+use embassy_boot_stm32::*;
+use embassy_stm32::flash::{Flash, ERASE_SIZE};
+
+#[entry]
+fn main() -> ! {
+    let p = embassy_stm32::init(Default::default());
+
+    // Uncomment this if you are debugging the bootloader with debugger/RTT attached,
+    // as it prevents a hard fault when accessing flash 'too early' after boot.
+    /*
+        for i in 0..10000000 {
+            cortex_m::asm::nop();
+        }
+    */
+
+    let mut bl: BootLoader<ERASE_SIZE> = BootLoader::default();
+    let mut flash = Flash::unlock(p.FLASH);
+    let start = bl.prepare(&mut SingleFlashProvider::new(&mut flash));
+    core::mem::drop(flash);
+    unsafe { bl.load(start) }
+}
+
+#[no_mangle]
+#[cfg_attr(target_os = "none", link_section = ".HardFault.user")]
+unsafe extern "C" fn HardFault() {
+    cortex_m::peripheral::SCB::sys_reset();
+}
+
+#[exception]
+unsafe fn DefaultHandler(_: i16) -> ! {
+    const SCB_ICSR: *const u32 = 0xE000_ED04 as *const u32;
+    let irqn = core::ptr::read_volatile(SCB_ICSR) as u8 as i16 - 16;
+
+    panic!("DefaultHandler #{:?}", irqn);
+}
+
+#[panic_handler]
+fn panic(_info: &core::panic::PanicInfo) -> ! {
+    cortex_m::asm::udf();
+}