1 files changed, 150 insertions, 0 deletions

diff --git a/embassy-embedded-hal/src/flash/partition.rs b/embassy-embedded-hal/src/flash/partition.rs
new file mode 100644
index 000000000..084425e95
--- /dev/null
+++ b/embassy-embedded-hal/src/flash/partition.rs
@@ -0,0 +1,150 @@
+use embassy_sync::blocking_mutex::raw::RawMutex;
+use embassy_sync::mutex::Mutex;
+use embedded_storage::nor_flash::{ErrorType, NorFlashError, NorFlashErrorKind};
+#[cfg(feature = "nightly")]
+use embedded_storage_async::nor_flash::{NorFlash, ReadNorFlash};
+
+/// A logical partition of an underlying shared flash
+///
+/// A partition holds an offset and a size of the flash,
+/// and is restricted to operate with that range.
+/// There is no guarantee that muliple partitions on the same flash
+/// operate on mutually exclusive ranges - such a separation is up to
+/// the user to guarantee.
+pub struct Partition<'a, M: RawMutex, T> {
+    flash: &'a Mutex<M, T>,
+    offset: u32,
+    size: u32,
+}
+
+#[derive(Debug)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum Error<T> {
+    Partition,
+    OutOfBounds,
+    Flash(T),
+}
+
+impl<'a, M: RawMutex, T> Partition<'a, M, T> {
+    /// Create a new partition
+    pub const fn new(flash: &'a Mutex<M, T>, offset: u32, size: u32) -> Self {
+        Self { flash, offset, size }
+    }
+}
+
+impl<T: NorFlashError> NorFlashError for Error<T> {
+    fn kind(&self) -> NorFlashErrorKind {
+        match self {
+            Error::Partition => NorFlashErrorKind::Other,
+            Error::OutOfBounds => NorFlashErrorKind::OutOfBounds,
+            Error::Flash(f) => f.kind(),
+        }
+    }
+}
+
+impl<M: RawMutex, T: ErrorType> ErrorType for Partition<'_, M, T> {
+    type Error = Error<T::Error>;
+}
+
+#[cfg(feature = "nightly")]
+impl<M: RawMutex, T: ReadNorFlash> ReadNorFlash for Partition<'_, M, T> {
+    const READ_SIZE: usize = T::READ_SIZE;
+
+    async fn read(&mut self, offset: u32, bytes: &mut [u8]) -> Result<(), Self::Error> {
+        if self.offset % T::READ_SIZE as u32 != 0 || self.size % T::READ_SIZE as u32 != 0 {
+            return Err(Error::Partition);
+        }
+        if offset + bytes.len() as u32 > self.size {
+            return Err(Error::OutOfBounds);
+        }
+
+        let mut flash = self.flash.lock().await;
+        flash.read(self.offset + offset, bytes).await.map_err(Error::Flash)
+    }
+
+    fn capacity(&self) -> usize {
+        self.size as usize
+    }
+}
+
+#[cfg(feature = "nightly")]
+impl<M: RawMutex, T: NorFlash> NorFlash for Partition<'_, M, T> {
+    const WRITE_SIZE: usize = T::WRITE_SIZE;
+    const ERASE_SIZE: usize = T::ERASE_SIZE;
+
+    async fn write(&mut self, offset: u32, bytes: &[u8]) -> Result<(), Self::Error> {
+        if self.offset % T::WRITE_SIZE as u32 != 0 || self.size % T::WRITE_SIZE as u32 != 0 {
+            return Err(Error::Partition);
+        }
+        if offset + bytes.len() as u32 > self.size {
+            return Err(Error::OutOfBounds);
+        }
+
+        let mut flash = self.flash.lock().await;
+        flash.write(self.offset + offset, bytes).await.map_err(Error::Flash)
+    }
+
+    async fn erase(&mut self, from: u32, to: u32) -> Result<(), Self::Error> {
+        if self.offset % T::ERASE_SIZE as u32 != 0 || self.size % T::ERASE_SIZE as u32 != 0 {
+            return Err(Error::Partition);
+        }
+        if to > self.size {
+            return Err(Error::OutOfBounds);
+        }
+
+        let mut flash = self.flash.lock().await;
+        flash
+            .erase(self.offset + from, self.offset + to)
+            .await
+            .map_err(Error::Flash)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use embassy_sync::blocking_mutex::raw::NoopRawMutex;
+
+    use super::*;
+    use crate::flash::mem_flash::MemFlash;
+
+    #[futures_test::test]
+    async fn can_read() {
+        let mut flash = MemFlash::<1024, 128, 4>::default();
+        flash.mem[12..20].fill(0xAA);
+
+        let flash = Mutex::<NoopRawMutex, _>::new(flash);
+        let mut partition = Partition::new(&flash, 8, 12);
+
+        let mut read_buf = [0; 8];
+        partition.read(4, &mut read_buf).await.unwrap();
+
+        assert!(read_buf.iter().position(|&x| x != 0xAA).is_none());
+    }
+
+    #[futures_test::test]
+    async fn can_write() {
+        let flash = MemFlash::<1024, 128, 4>::default();
+
+        let flash = Mutex::<NoopRawMutex, _>::new(flash);
+        let mut partition = Partition::new(&flash, 8, 12);
+
+        let write_buf = [0xAA; 8];
+        partition.write(4, &write_buf).await.unwrap();
+
+        let flash = flash.try_lock().unwrap();
+        assert!(flash.mem[12..20].iter().position(|&x| x != 0xAA).is_none());
+    }
+
+    #[futures_test::test]
+    async fn can_erase() {
+        let flash = MemFlash::<1024, 128, 4>::new(0x00);
+
+        let flash = Mutex::<NoopRawMutex, _>::new(flash);
+        let mut partition = Partition::new(&flash, 128, 256);
+
+        partition.erase(0, 128).await.unwrap();
+
+        let flash = flash.try_lock().unwrap();
+        assert!(flash.mem[128..256].iter().position(|&x| x != 0xFF).is_none());
+    }
+}