tool: Use From<T> for slightly neater error handling

tool/src/access/hid.rs

@@ -38,12 +38,12 @@ impl AccessHid {
             hid_data[HID_DATA + i] = data[i];
         }
 
-        let count = self.device.write(&hid_data).map_err(Error::Hid)?;
+        let count = self.device.write(&hid_data)?;
         if count != hid_data.len() {
             return Err(Error::Verify);
         }
 
-        let count = self.device.read_timeout(&mut hid_data[1..], self.timeout).map_err(Error::Hid)?;
+        let count = self.device.read_timeout(&mut hid_data[1..], self.timeout)?;
         if count == hid_data.len() - 1 {
             for i in 0..data.len() {
                 data[i] = hid_data[HID_DATA + i];

tool/src/access/lpc/linux.rs

@@ -111,8 +111,8 @@ impl AccessLpcLinux {
             )));
         }
 
-        let cmd = PortLock::new(SMFI_CMD_BASE, SMFI_CMD_BASE + SMFI_CMD_SIZE as u16 - 1).map_err(Error::Io)?;
-        let dbg = PortLock::new(SMFI_DBG_BASE, SMFI_DBG_BASE + SMFI_DBG_SIZE as u16 - 1).map_err(Error::Io)?;
+        let cmd = PortLock::new(SMFI_CMD_BASE, SMFI_CMD_BASE + SMFI_CMD_SIZE as u16 - 1)?;
+        let dbg = PortLock::new(SMFI_DBG_BASE, SMFI_DBG_BASE + SMFI_DBG_SIZE as u16 - 1)?;
         Ok(Self {
             cmd,
             dbg,
@@ -122,18 +122,18 @@ impl AccessLpcLinux {
 
     /// Read from the command space
     unsafe fn read_cmd(&mut self, addr: u8) -> Result<u8, Error> {
-        self.cmd.read(addr as u16).map_err(Error::Io)
+        Ok(self.cmd.read(addr as u16)?)
     }
 
     /// Write to the command space
     unsafe fn write_cmd(&mut self, addr: u8, data: u8) -> Result<(), Error> {
-        self.cmd.write(addr as u16, data).map_err(Error::Io)
+        Ok(self.cmd.write(addr as u16, data)?)
     }
 
     /// Read from the debug space
     //TODO: better public interface
     pub unsafe fn read_debug(&mut self, addr: u8) -> Result<u8, Error> {
-        self.dbg.read(addr as u16).map_err(Error::Io)
+        Ok(self.dbg.read(addr as u16)?)
     }
 
     /// Returns Ok if a command can be sent

tool/src/error.rs

@@ -26,3 +26,17 @@ pub enum Error {
     #[cfg(feature = "hidapi")]
     Hid(hidapi::HidError),
 }
+
+#[cfg(feature = "std")]
+impl From<std::io::Error> for Error {
+    fn from(error: std::io::Error) -> Self {
+        Self::Io(error)
+    }
+}
+
+#[cfg(feature = "hidapi")]
+impl From<hidapi::HidError> for Error {
+    fn from(error: hidapi::HidError) -> Self {
+        Self::Hid(error)
+    }
+}