Add minimal UART driver for console.
Bug: 223166344
Test: Ran unprotected VM under crosvm.
Change-Id: I4e779ab0c87597db9384247f269b2b28f6e18b30
diff --git a/pvmfw/src/console.rs b/pvmfw/src/console.rs
new file mode 100644
index 0000000..d44eb92
--- /dev/null
+++ b/pvmfw/src/console.rs
@@ -0,0 +1,61 @@
+// Copyright 2022, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Console driver for 8250 UART.
+
+use crate::uart::Uart;
+use core::fmt::{write, Arguments, Write};
+use spin::mutex::SpinMutex;
+
+const BASE_ADDRESS: usize = 0x3f8;
+
+static CONSOLE: SpinMutex<Option<Uart>> = SpinMutex::new(None);
+
+/// Initialises a new instance of the UART driver and returns it.
+fn create() -> Uart {
+ // Safe because BASE_ADDRESS is the base of the MMIO region for a UART and is mapped as device
+ // memory.
+ unsafe { Uart::new(BASE_ADDRESS) }
+}
+
+/// Initialises the global instance of the UART driver. This must be called before using
+/// the `print!` and `println!` macros.
+pub fn init() {
+ let uart = create();
+ CONSOLE.lock().replace(uart);
+}
+
+/// Writes a string to the console.
+///
+/// Panics if [`init`] was not called first.
+pub fn write_str(s: &str) {
+ CONSOLE.lock().as_mut().unwrap().write_str(s).unwrap();
+}
+
+/// Writes a formatted string to the console.
+///
+/// Panics if [`init`] was not called first.
+#[allow(unused)]
+pub fn write_args(format_args: Arguments) {
+ write(CONSOLE.lock().as_mut().unwrap(), format_args).unwrap();
+}
+
+/// Reinitialises the UART driver and writes a string to it.
+///
+/// This is intended for use in situations where the UART may be in an unknown state or the global
+/// instance may be locked, such as in an exception handler or panic handler.
+pub fn emergency_write_str(s: &str) {
+ let mut uart = create();
+ let _ = uart.write_str(s);
+}