Refactor SMFI interface and ectool

tool/src/super_io.rs

@@ -1,25 +1,28 @@
 use hwio::{Io, Pio};
 
+/// Super I/O interface provided by LPC ECs
 pub struct SuperIo {
     addr: Pio<u8>,
     data: Pio<u8>,
 }
 
 impl SuperIo {
-    /// Create a new SuperIo. `base` identifies the address port. The data port
-    /// will be `base + 1`
-    pub fn new(base: u16) -> Self {
+    /// Create a new SuperIo using direct hardware access. `base` identifies the address port. The
+    /// data port will be `base + 1`. Unsafe due to no mutual exclusion
+    pub unsafe fn new(base: u16) -> Self {
         Self {
             addr: Pio::new(base),
             data: Pio::new(base + 1),
         }
     }
 
+    /// Read a Super I/O register
     pub unsafe fn read(&mut self, addr: u8) -> u8 {
         self.addr.write(addr);
         self.data.read()
     }
 
+    /// Write a Super I/O register
     pub unsafe fn write(&mut self, addr: u8, data: u8) {
         self.addr.write(addr);
         self.data.write(data);