devices: doc for legacy devices

Doc for legacy devices

Signed-off-by: Diana Popa <dpopa@amazon.com>

Author: dianpopa

src/vmm/src/devices/legacy/rtc_pl031.rs

@@ -5,6 +5,7 @@ use std::convert::TryInto;
 
 use logger::{warn, IncMetric, RTCDeviceMetrics, METRICS};
 
+/// Wrapper over vm_superio's RTC implementation.
 #[derive(Debug)]
 pub struct RTCDevice(pub vm_superio::Rtc<&'static RTCDeviceMetrics>);
 

src/vmm/src/devices/legacy/serial.rs

@@ -20,10 +20,10 @@ use vm_superio::{Serial, Trigger};
 
 use crate::devices::legacy::EventFdTrigger;
 
-// Received Data Available interrupt - for letting the driver know that
-// there is some pending data to be processed.
+/// Received Data Available interrupt - for letting the driver know that
+/// there is some pending data to be processed.
 pub const IER_RDA_BIT: u8 = 0b0000_0001;
-// Received Data Available interrupt offset
+/// Received Data Available interrupt offset
 pub const IER_RDA_OFFSET: u8 = 1;
 
 #[derive(Debug)]