From b6ac53e5a20dc6088b18d6ff7b2a580cc123e4d3 Mon Sep 17 00:00:00 2001
From: tfx2001 <tfx2001@outlook.com>
Date: Thu, 25 Jul 2024 02:25:08 +0800
Subject: [PATCH] feat(board): support SBI call #02 getchar

Support SBI call #0 Console Getchar from UART0.

Signed-off-by: tfx2001 <tfx2001@outlook.com>
---
 src/board/mod.rs  | 22 ++++++++++++++++++----
 src/board/uart.rs | 15 +++++++++++++++
 src/trap.rs       |  6 +++++-
 3 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/src/board/mod.rs b/src/board/mod.rs
index b245b69..ccc5f90 100644
--- a/src/board/mod.rs
+++ b/src/board/mod.rs
@@ -24,7 +24,7 @@ static UART: Mutex<MaybeUninit<Uart>> = Mutex::new(MaybeUninit::uninit());
 #[macro_export]
 macro_rules! print {
     ($fmt: literal $(, $($args: tt)+)?) => {
-        $crate::board::_print(format_args!($fmt $(, $($args)+)?));
+        $crate::board::putchar(format_args!($fmt $(, $($args)+)?));
     };
 }
 
@@ -32,7 +32,7 @@ macro_rules! print {
 macro_rules! println {
     () => ($crate::print!("\n"));
     ($($arg:tt)*) => {{
-        $crate::board::_print(core::format_args!($($arg)*));
+        $crate::board::putchar(core::format_args!($($arg)*));
         $crate::println!();
     }}
 }
@@ -47,7 +47,7 @@ pub fn board_init() {
     pins.setup();
 
     let uart = Uart::new(pac::UART0);
-    uart.setup(250_000, clock.get_clk_freq(clocks::URT0));
+    uart.setup(115_200, clock.get_clk_freq(clocks::URT0));
     *UART.lock() = MaybeUninit::new(uart);
 
     let cpu0_clock_freq = clock.get_cpu0_clk_freq();
@@ -68,12 +68,26 @@ pub fn board_init() {
 }
 
 #[inline]
-pub fn _print(args: fmt::Arguments) {
+pub fn putchar(args: fmt::Arguments) {
     let mut guard = UART.lock();
 
     unsafe { guard.assume_init_mut().write_fmt(args).unwrap() }
 }
 
+#[inline]
+pub fn getchar() -> usize {
+    let mut guard = UART.lock();
+    let mut c: u8 = 0;
+
+    unsafe {
+        if guard.assume_init_mut().receive_byte(&mut c) {
+            c as _
+        } else {
+            usize::MAX
+        }
+    }
+}
+
 pub fn board_init_timer() -> MachineTimer {
     MachineTimer::new(pac::MCHTMR)
 }
diff --git a/src/board/uart.rs b/src/board/uart.rs
index 1d6e580..8685172 100644
--- a/src/board/uart.rs
+++ b/src/board/uart.rs
@@ -39,11 +39,26 @@ impl Uart {
         self.inner.lsr().read().thre()
     }
 
+    #[inline]
+    fn is_data_ready(&self) -> bool {
+        self.inner.lsr().read().dr()
+    }
+
     #[inline]
     pub fn send_byte(&self, byte: u8) {
         while !self.is_tx_fifo_empty() {}
         self.inner.dll().write(|w| w.set_dll(byte));
     }
+
+    #[inline]
+    pub fn receive_byte(&self, byte: &mut u8) -> bool {
+        if self.is_data_ready() {
+            *byte = self.inner.rbr().read().rbr();
+            true
+        } else {
+            false
+        }
+    }
 }
 
 impl Write for Uart {
diff --git a/src/trap.rs b/src/trap.rs
index 637380c..68db243 100644
--- a/src/trap.rs
+++ b/src/trap.rs
@@ -5,6 +5,7 @@ use riscv::register::{
 };
 use rustsbi::RustSBI;
 
+use crate::board;
 use crate::extension::SBI;
 use crate::local_hsm;
 use crate::print;
@@ -128,7 +129,10 @@ pub extern "C" fn fast_handler(
                                 ret.error = 0;
                                 ret.value = a1;
                             }
-                            legacy::LEGACY_CONSOLE_GETCHAR => unimplemented!(),
+                            legacy::LEGACY_CONSOLE_GETCHAR => {
+                                ret.error = board::getchar();
+                                ret.value = a1;
+                            }
                             _ => unimplemented!(
                                 "EID: {:#010x} FID: {:#010x} is not implemented!",
                                 a7,