1 files changed, 421 insertions, 0 deletions

diff --git a/embassy-boot/boot/src/boot_loader.rs b/embassy-boot/boot/src/boot_loader.rs
new file mode 100644
index 000000000..a8c19197b
--- /dev/null
+++ b/embassy-boot/boot/src/boot_loader.rs
@@ -0,0 +1,421 @@
+use core::cell::RefCell;
+
+use embassy_embedded_hal::flash::partition::BlockingPartition;
+use embassy_sync::blocking_mutex::raw::NoopRawMutex;
+use embassy_sync::blocking_mutex::Mutex;
+use embedded_storage::nor_flash::{NorFlash, NorFlashError, NorFlashErrorKind};
+
+use crate::{State, BOOT_MAGIC, STATE_ERASE_VALUE, SWAP_MAGIC};
+
+/// Errors returned by bootloader
+#[derive(PartialEq, Eq, Debug)]
+pub enum BootError {
+    /// Error from flash.
+    Flash(NorFlashErrorKind),
+    /// Invalid bootloader magic
+    BadMagic,
+}
+
+#[cfg(feature = "defmt")]
+impl defmt::Format for BootError {
+    fn format(&self, fmt: defmt::Formatter) {
+        match self {
+            BootError::Flash(_) => defmt::write!(fmt, "BootError::Flash(_)"),
+            BootError::BadMagic => defmt::write!(fmt, "BootError::BadMagic"),
+        }
+    }
+}
+
+impl<E> From<E> for BootError
+where
+    E: NorFlashError,
+{
+    fn from(error: E) -> Self {
+        BootError::Flash(error.kind())
+    }
+}
+
+/// Bootloader flash configuration holding the three flashes used by the bootloader
+///
+/// If only a single flash is actually used, then that flash should be partitioned into three partitions before use.
+/// The easiest way to do this is to use [`BootLoaderConfig::from_linkerfile_blocking`] which will partition
+/// the provided flash according to symbols defined in the linkerfile.
+pub struct BootLoaderConfig<ACTIVE, DFU, STATE> {
+    /// Flash type used for the active partition - the partition which will be booted from.
+    pub active: ACTIVE,
+    /// Flash type used for the dfu partition - the partition which will be swapped in when requested.
+    pub dfu: DFU,
+    /// Flash type used for the state partition.
+    pub state: STATE,
+}
+
+impl<'a, FLASH: NorFlash>
+    BootLoaderConfig<
+        BlockingPartition<'a, NoopRawMutex, FLASH>,
+        BlockingPartition<'a, NoopRawMutex, FLASH>,
+        BlockingPartition<'a, NoopRawMutex, FLASH>,
+    >
+{
+    /// Create a bootloader config from the flash and address symbols defined in the linkerfile
+    // #[cfg(target_os = "none")]
+    pub fn from_linkerfile_blocking(flash: &'a Mutex<NoopRawMutex, RefCell<FLASH>>) -> 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 {
+            let start = &__bootloader_active_start as *const u32 as u32;
+            let end = &__bootloader_active_end as *const u32 as u32;
+            trace!("ACTIVE: 0x{:x} - 0x{:x}", start, end);
+
+            BlockingPartition::new(flash, start, end - start)
+        };
+        let dfu = unsafe {
+            let start = &__bootloader_dfu_start as *const u32 as u32;
+            let end = &__bootloader_dfu_end as *const u32 as u32;
+            trace!("DFU: 0x{:x} - 0x{:x}", start, end);
+
+            BlockingPartition::new(flash, start, end - start)
+        };
+        let state = unsafe {
+            let start = &__bootloader_state_start as *const u32 as u32;
+            let end = &__bootloader_state_end as *const u32 as u32;
+            trace!("STATE: 0x{:x} - 0x{:x}", start, end);
+
+            BlockingPartition::new(flash, start, end - start)
+        };
+
+        Self { active, dfu, state }
+    }
+}
+
+/// BootLoader works with any flash implementing embedded_storage.
+pub struct BootLoader<ACTIVE: NorFlash, DFU: NorFlash, STATE: NorFlash> {
+    active: ACTIVE,
+    dfu: DFU,
+    /// The state partition has the following format:
+    /// All ranges are in multiples of WRITE_SIZE bytes.
+    /// | Range    | Description                                                                      |
+    /// | 0..1     | Magic indicating bootloader state. BOOT_MAGIC means boot, SWAP_MAGIC means swap. |
+    /// | 1..2     | Progress validity. ERASE_VALUE means valid, !ERASE_VALUE means invalid.          |
+    /// | 2..2 + N | Progress index used while swapping or reverting      
+    state: STATE,
+}
+
+impl<ACTIVE: NorFlash, DFU: NorFlash, STATE: NorFlash> BootLoader<ACTIVE, DFU, STATE> {
+    /// Get the page size which is the "unit of operation" within the bootloader.
+    const PAGE_SIZE: u32 = if ACTIVE::ERASE_SIZE > DFU::ERASE_SIZE {
+        ACTIVE::ERASE_SIZE as u32
+    } else {
+        DFU::ERASE_SIZE as u32
+    };
+
+    /// Create a new instance of a bootloader with the flash partitions.
+    ///
+    /// - All partitions must be aligned with the PAGE_SIZE const generic parameter.
+    /// - The dfu partition must be at least PAGE_SIZE bigger than the active partition.
+    pub fn new(config: BootLoaderConfig<ACTIVE, DFU, STATE>) -> Self {
+        Self {
+            active: config.active,
+            dfu: config.dfu,
+            state: config.state,
+        }
+    }
+
+    /// Perform necessary boot preparations like swapping images.
+    ///
+    /// The DFU partition is assumed to be 1 page bigger than the active partition for the swap
+    /// algorithm to work correctly.
+    ///
+    /// The provided aligned_buf argument must satisfy any alignment requirements
+    /// given by the partition flashes. All flash operations will use this buffer.
+    ///
+    /// SWAPPING
+    ///
+    /// Assume a flash size of 3 pages for the active partition, and 4 pages for the DFU partition.
+    /// The swap index contains the copy progress, as to allow continuation of the copy process on
+    /// power failure. The index counter is represented within 1 or more pages (depending on total
+    /// flash size), where a page X is considered swapped if index at location (X + WRITE_SIZE)
+    /// contains a zero value. This ensures that index updates can be performed atomically and
+    /// avoid a situation where the wrong index value is set (page write size is "atomic").
+    ///
+    /// +-----------+------------+--------+--------+--------+--------+
+    /// | Partition | Swap Index | Page 0 | Page 1 | Page 3 | Page 4 |
+    /// +-----------+------------+--------+--------+--------+--------+
+    /// |    Active |          0 |      1 |      2 |      3 |      - |
+    /// |       DFU |          0 |      3 |      2 |      1 |      X |
+    /// +-----------+------------+--------+--------+--------+--------+
+    ///
+    /// The algorithm starts by copying 'backwards', and after the first step, the layout is
+    /// as follows:
+    ///
+    /// +-----------+------------+--------+--------+--------+--------+
+    /// | Partition | Swap Index | Page 0 | Page 1 | Page 3 | Page 4 |
+    /// +-----------+------------+--------+--------+--------+--------+
+    /// |    Active |          1 |      1 |      2 |      1 |      - |
+    /// |       DFU |          1 |      3 |      2 |      1 |      3 |
+    /// +-----------+------------+--------+--------+--------+--------+
+    ///
+    /// The next iteration performs the same steps
+    ///
+    /// +-----------+------------+--------+--------+--------+--------+
+    /// | Partition | Swap Index | Page 0 | Page 1 | Page 3 | Page 4 |
+    /// +-----------+------------+--------+--------+--------+--------+
+    /// |    Active |          2 |      1 |      2 |      1 |      - |
+    /// |       DFU |          2 |      3 |      2 |      2 |      3 |
+    /// +-----------+------------+--------+--------+--------+--------+
+    ///
+    /// And again until we're done
+    ///
+    /// +-----------+------------+--------+--------+--------+--------+
+    /// | Partition | Swap Index | Page 0 | Page 1 | Page 3 | Page 4 |
+    /// +-----------+------------+--------+--------+--------+--------+
+    /// |    Active |          3 |      3 |      2 |      1 |      - |
+    /// |       DFU |          3 |      3 |      1 |      2 |      3 |
+    /// +-----------+------------+--------+--------+--------+--------+
+    ///
+    /// REVERTING
+    ///
+    /// The reverting algorithm uses the swap index to discover that images were swapped, but that
+    /// the application failed to mark the boot successful. In this case, the revert algorithm will
+    /// run.
+    ///
+    /// The revert index is located separately from the swap index, to ensure that revert can continue
+    /// on power failure.
+    ///
+    /// The revert algorithm works forwards, by starting copying into the 'unused' DFU page at the start.
+    ///
+    /// +-----------+--------------+--------+--------+--------+--------+
+    /// | Partition | Revert Index | Page 0 | Page 1 | Page 3 | Page 4 |
+    //*/
+    /// +-----------+--------------+--------+--------+--------+--------+
+    /// |    Active |            3 |      1 |      2 |      1 |      - |
+    /// |       DFU |            3 |      3 |      1 |      2 |      3 |
+    /// +-----------+--------------+--------+--------+--------+--------+
+    ///
+    ///
+    /// +-----------+--------------+--------+--------+--------+--------+
+    /// | Partition | Revert Index | Page 0 | Page 1 | Page 3 | Page 4 |
+    /// +-----------+--------------+--------+--------+--------+--------+
+    /// |    Active |            3 |      1 |      2 |      1 |      - |
+    /// |       DFU |            3 |      3 |      2 |      2 |      3 |
+    /// +-----------+--------------+--------+--------+--------+--------+
+    ///
+    /// +-----------+--------------+--------+--------+--------+--------+
+    /// | Partition | Revert Index | Page 0 | Page 1 | Page 3 | Page 4 |
+    /// +-----------+--------------+--------+--------+--------+--------+
+    /// |    Active |            3 |      1 |      2 |      3 |      - |
+    /// |       DFU |            3 |      3 |      2 |      1 |      3 |
+    /// +-----------+--------------+--------+--------+--------+--------+
+    ///
+    pub fn prepare_boot(&mut self, aligned_buf: &mut [u8]) -> Result<State, BootError> {
+        // Ensure we have enough progress pages to store copy progress
+        assert_eq!(0, Self::PAGE_SIZE % aligned_buf.len() as u32);
+        assert_eq!(0, Self::PAGE_SIZE % ACTIVE::WRITE_SIZE as u32);
+        assert_eq!(0, Self::PAGE_SIZE % ACTIVE::ERASE_SIZE as u32);
+        assert_eq!(0, Self::PAGE_SIZE % DFU::WRITE_SIZE as u32);
+        assert_eq!(0, Self::PAGE_SIZE % DFU::ERASE_SIZE as u32);
+        assert!(aligned_buf.len() >= STATE::WRITE_SIZE);
+        assert_eq!(0, aligned_buf.len() % ACTIVE::WRITE_SIZE);
+        assert_eq!(0, aligned_buf.len() % DFU::WRITE_SIZE);
+
+        assert_partitions(&self.active, &self.dfu, &self.state, Self::PAGE_SIZE);
+
+        // Copy contents from partition N to active
+        let state = self.read_state(aligned_buf)?;
+        if state == State::Swap {
+            //
+            // Check if we already swapped. If we're in the swap state, this means we should revert
+            // since the app has failed to mark boot as successful
+            //
+            if !self.is_swapped(aligned_buf)? {
+                trace!("Swapping");
+                self.swap(aligned_buf)?;
+                trace!("Swapping done");
+            } else {
+                trace!("Reverting");
+                self.revert(aligned_buf)?;
+
+                let state_word = &mut aligned_buf[..STATE::WRITE_SIZE];
+
+                // Invalidate progress
+                state_word.fill(!STATE_ERASE_VALUE);
+                self.state.write(STATE::WRITE_SIZE as u32, state_word)?;
+
+                // Clear magic and progress
+                self.state.erase(0, self.state.capacity() as u32)?;
+
+                // Set magic
+                state_word.fill(BOOT_MAGIC);
+                self.state.write(0, state_word)?;
+            }
+        }
+        Ok(state)
+    }
+
+    fn is_swapped(&mut self, aligned_buf: &mut [u8]) -> Result<bool, BootError> {
+        let page_count = self.active.capacity() / Self::PAGE_SIZE as usize;
+        let progress = self.current_progress(aligned_buf)?;
+
+        Ok(progress >= page_count * 2)
+    }
+
+    fn current_progress(&mut self, aligned_buf: &mut [u8]) -> Result<usize, BootError> {
+        let write_size = STATE::WRITE_SIZE as u32;
+        let max_index = ((self.state.capacity() - STATE::WRITE_SIZE) / STATE::WRITE_SIZE) - 2;
+        let state_word = &mut aligned_buf[..write_size as usize];
+
+        self.state.read(write_size, state_word)?;
+        if state_word.iter().any(|&b| b != STATE_ERASE_VALUE) {
+            // Progress is invalid
+            return Ok(max_index);
+        }
+
+        for index in 0..max_index {
+            self.state.read((2 + index) as u32 * write_size, state_word)?;
+
+            if state_word.iter().any(|&b| b == STATE_ERASE_VALUE) {
+                return Ok(index);
+            }
+        }
+        Ok(max_index)
+    }
+
+    fn update_progress(&mut self, progress_index: usize, aligned_buf: &mut [u8]) -> Result<(), BootError> {
+        let state_word = &mut aligned_buf[..STATE::WRITE_SIZE];
+        state_word.fill(!STATE_ERASE_VALUE);
+        self.state
+            .write((2 + progress_index) as u32 * STATE::WRITE_SIZE as u32, state_word)?;
+        Ok(())
+    }
+
+    fn copy_page_once_to_active(
+        &mut self,
+        progress_index: usize,
+        from_offset: u32,
+        to_offset: u32,
+        aligned_buf: &mut [u8],
+    ) -> Result<(), BootError> {
+        if self.current_progress(aligned_buf)? <= progress_index {
+            let page_size = Self::PAGE_SIZE as u32;
+
+            self.active.erase(to_offset, to_offset + page_size)?;
+
+            for offset_in_page in (0..page_size).step_by(aligned_buf.len()) {
+                self.dfu.read(from_offset + offset_in_page as u32, aligned_buf)?;
+                self.active.write(to_offset + offset_in_page as u32, aligned_buf)?;
+            }
+
+            self.update_progress(progress_index, aligned_buf)?;
+        }
+        Ok(())
+    }
+
+    fn copy_page_once_to_dfu(
+        &mut self,
+        progress_index: usize,
+        from_offset: u32,
+        to_offset: u32,
+        aligned_buf: &mut [u8],
+    ) -> Result<(), BootError> {
+        if self.current_progress(aligned_buf)? <= progress_index {
+            let page_size = Self::PAGE_SIZE as u32;
+
+            self.dfu.erase(to_offset as u32, to_offset + page_size)?;
+
+            for offset_in_page in (0..page_size).step_by(aligned_buf.len()) {
+                self.active.read(from_offset + offset_in_page as u32, aligned_buf)?;
+                self.dfu.write(to_offset + offset_in_page as u32, aligned_buf)?;
+            }
+
+            self.update_progress(progress_index, aligned_buf)?;
+        }
+        Ok(())
+    }
+
+    fn swap(&mut self, aligned_buf: &mut [u8]) -> Result<(), BootError> {
+        let page_count = self.active.capacity() as u32 / Self::PAGE_SIZE;
+        for page_num in 0..page_count {
+            let progress_index = (page_num * 2) as usize;
+
+            // Copy active page to the 'next' DFU page.
+            let active_from_offset = (page_count - 1 - page_num) * Self::PAGE_SIZE;
+            let dfu_to_offset = (page_count - page_num) * Self::PAGE_SIZE;
+            //trace!("Copy active {} to dfu {}", active_from_offset, dfu_to_offset);
+            self.copy_page_once_to_dfu(progress_index, active_from_offset, dfu_to_offset, aligned_buf)?;
+
+            // Copy DFU page to the active page
+            let active_to_offset = (page_count - 1 - page_num) * Self::PAGE_SIZE;
+            let dfu_from_offset = (page_count - 1 - page_num) * Self::PAGE_SIZE;
+            //trace!("Copy dfy {} to active {}", dfu_from_offset, active_to_offset);
+            self.copy_page_once_to_active(progress_index + 1, dfu_from_offset, active_to_offset, aligned_buf)?;
+        }
+
+        Ok(())
+    }
+
+    fn revert(&mut self, aligned_buf: &mut [u8]) -> Result<(), BootError> {
+        let page_count = self.active.capacity() as u32 / Self::PAGE_SIZE;
+        for page_num in 0..page_count {
+            let progress_index = (page_count * 2 + page_num * 2) as usize;
+
+            // Copy the bad active page to the DFU page
+            let active_from_offset = page_num * Self::PAGE_SIZE;
+            let dfu_to_offset = page_num * Self::PAGE_SIZE;
+            self.copy_page_once_to_dfu(progress_index, active_from_offset, dfu_to_offset, aligned_buf)?;
+
+            // Copy the DFU page back to the active page
+            let active_to_offset = page_num * Self::PAGE_SIZE;
+            let dfu_from_offset = (page_num + 1) * Self::PAGE_SIZE;
+            self.copy_page_once_to_active(progress_index + 1, dfu_from_offset, active_to_offset, aligned_buf)?;
+        }
+
+        Ok(())
+    }
+
+    fn read_state(&mut self, aligned_buf: &mut [u8]) -> Result<State, BootError> {
+        let state_word = &mut aligned_buf[..STATE::WRITE_SIZE];
+        self.state.read(0, state_word)?;
+
+        if !state_word.iter().any(|&b| b != SWAP_MAGIC) {
+            Ok(State::Swap)
+        } else {
+            Ok(State::Boot)
+        }
+    }
+}
+
+fn assert_partitions<ACTIVE: NorFlash, DFU: NorFlash, STATE: NorFlash>(
+    active: &ACTIVE,
+    dfu: &DFU,
+    state: &STATE,
+    page_size: u32,
+) {
+    assert_eq!(active.capacity() as u32 % page_size, 0);
+    assert_eq!(dfu.capacity() as u32 % page_size, 0);
+    assert!(dfu.capacity() as u32 - active.capacity() as u32 >= page_size);
+    assert!(2 + 2 * (active.capacity() as u32 / page_size) <= state.capacity() as u32 / STATE::WRITE_SIZE as u32);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::mem_flash::MemFlash;
+
+    #[test]
+    #[should_panic]
+    fn test_range_asserts() {
+        const ACTIVE_SIZE: usize = 4194304 - 4096;
+        const DFU_SIZE: usize = 4194304;
+        const STATE_SIZE: usize = 4096;
+        static ACTIVE: MemFlash<ACTIVE_SIZE, 4, 4> = MemFlash::new(0xFF);
+        static DFU: MemFlash<DFU_SIZE, 4, 4> = MemFlash::new(0xFF);
+        static STATE: MemFlash<STATE_SIZE, 4, 4> = MemFlash::new(0xFF);
+        assert_partitions(&ACTIVE, &DFU, &STATE, 4096);
+    }
+}