feat: embassy-boot for rp2040

Add embassy-boot support for RP2040, with examples for the Raspberry Pi
Pico.

Co-authored-by: Mathias Koch <mk@blackbird.online>

embassy-boot/rp/src/lib.rs

@@ -0,0 +1,90 @@
+#![no_std]
+#![feature(type_alias_impl_trait)]
+#![warn(missing_docs)]
+#![doc = include_str!("../README.md")]
+mod fmt;
+
+pub use embassy_boot::{AlignedBuffer, BootFlash, FirmwareUpdater, FlashConfig, Partition, SingleFlashConfig, State};
+use embassy_rp::flash::{ERASE_SIZE, WRITE_SIZE};
+
+/// A bootloader for RP2040 devices.
+pub struct BootLoader {
+    boot: embassy_boot::BootLoader,
+    magic: AlignedBuffer<WRITE_SIZE>,
+    page: AlignedBuffer<ERASE_SIZE>,
+}
+
+impl BootLoader {
+    /// Create a new bootloader instance using the supplied partitions for active, dfu and state.
+    pub fn new(active: Partition, dfu: Partition, state: Partition) -> Self {
+        Self {
+            boot: embassy_boot::BootLoader::new(active, dfu, state),
+            magic: AlignedBuffer([0; WRITE_SIZE]),
+            page: AlignedBuffer([0; ERASE_SIZE]),
+        }
+    }
+
+    /// Inspect the bootloader state and perform actions required before booting, such as swapping
+    /// firmware.
+    pub fn prepare<F: FlashConfig>(&mut self, flash: &mut F) -> usize {
+        match self.boot.prepare_boot(flash, self.magic.as_mut(), self.page.as_mut()) {
+            Ok(_) => embassy_rp::flash::FLASH_BASE + self.boot.boot_address(),
+            Err(_) => panic!("boot prepare error!"),
+        }
+    }
+
+    /// Boots the application.
+    ///
+    /// # Safety
+    ///
+    /// This modifies the stack pointer and reset vector and will run code placed in the active partition.
+    pub unsafe fn load(&mut self, start: usize) -> ! {
+        trace!("Loading app at 0x{:x}", start);
+        #[allow(unused_mut)]
+        let mut p = cortex_m::Peripherals::steal();
+        #[cfg(not(armv6m))]
+        p.SCB.invalidate_icache();
+        p.SCB.vtor.write(start as u32);
+
+        cortex_m::asm::bootload(start as *const u32)
+    }
+}
+
+impl Default for BootLoader {
+    /// Create a new bootloader instance using parameters from linker script
+    fn default() -> Self {
+        extern "C" {
+            static __bootloader_state_start: u32;
+            static __bootloader_state_end: u32;
+            static __bootloader_active_start: u32;
+            static __bootloader_active_end: u32;
+            static __bootloader_dfu_start: u32;
+            static __bootloader_dfu_end: u32;
+        }
+
+        let active = unsafe {
+            Partition::new(
+                &__bootloader_active_start as *const u32 as usize,
+                &__bootloader_active_end as *const u32 as usize,
+            )
+        };
+        let dfu = unsafe {
+            Partition::new(
+                &__bootloader_dfu_start as *const u32 as usize,
+                &__bootloader_dfu_end as *const u32 as usize,
+            )
+        };
+        let state = unsafe {
+            Partition::new(
+                &__bootloader_state_start as *const u32 as usize,
+                &__bootloader_state_end as *const u32 as usize,
+            )
+        };
+
+        trace!("ACTIVE: 0x{:x} - 0x{:x}", active.from, active.to);
+        trace!("DFU: 0x{:x} - 0x{:x}", dfu.from, dfu.to);
+        trace!("STATE: 0x{:x} - 0x{:x}", state.from, state.to);
+
+        Self::new(active, dfu, state)
+    }
+}