Some clippy lints

.rustfmt.toml

@@ -0,0 +1,3 @@
+edition = "2021"
+max_width = 110
+newline_style = "Unix"

src/checksum.rs

@@ -1,6 +1,7 @@
 // Compute the checksum over the bytes of a block.
+#[allow(clippy::cast_possible_truncation)]
 pub fn checksum(bytes: &[u8]) -> u8 {
-    bytes.iter().fold(0u32, |x, y| x + (*y as u32)) as u8
+    bytes.iter().fold(0u32, |x, y| x + u32::from(*y)) as u8
 }
 
 // Validate the checksum

src/i2c.rs

@@ -36,6 +36,7 @@ pub fn write_to_bus(
     // Write 8 bytes at a time
     for (i, chunk) in data.chunks_exact(8).enumerate() {
         // Memory address
+        #[allow(clippy::cast_possible_truncation)]
         let address = memory_address + (i as u8) * 8;
         let mut msgs = [
             // Address to write to

src/io.rs

@@ -23,6 +23,7 @@ pub fn block_by_block_read(
                     // Read remaining blocks
                     match num_extensions {
                         0 => vec![],
+                        #[allow(clippy::cast_possible_truncation)]
                         _ => read(BLOCK_SIZE as u8, num_extensions * BLOCK_SIZE)?,
                     }
                 }