Move PL011 driver into the main workspace (#1040)

We now use that driver to implement the serial port on aarch64.

kernel/serial_port/src/lib.rs

@@ -82,6 +82,8 @@ pub fn init_serial_port(
     serial_port_address: SerialPortAddress,
     serial_port: SerialPortBasic,
 ) -> Option<&'static Arc<IrqSafeMutex<SerialPort>>> {
+    // Note: if we're called by device_manager, we cannot log (as we're modifying the logger config)
+
     #[cfg(target_arch = "aarch64")]
     if serial_port_address != SerialPortAddress::COM1 {
         return None;
@@ -309,7 +311,7 @@ fn serial_port_receive_deferred(
     let mut buf = DataChunk::empty();
     let bytes_read;
     let base_port;
-    
+
     let mut input_was_ignored = false;
     let mut send_result = Ok(());
 
@@ -331,9 +333,6 @@ fn serial_port_receive_deferred(
             // other than data being received, which is the only one we currently care about.
             return Ok(());
         }
-
-        #[cfg(target_arch = "aarch64")]
-        sp.enable_interrupt(SerialPortInterruptEvent::DataReceived, true);
     }
 
     if let Err(e) = send_result {
@@ -387,15 +386,18 @@ static INTERRUPT_ACTION_COM2_COM4: Once<Box<dyn Fn() + Send + Sync>> = Once::new
 
 // Cross-platform interrupt handler for COM1 and COM3 (IRQ 0x24 on x86_64).
 interrupt_handler!(com1_com3_interrupt_handler, Some(interrupts::IRQ_BASE_OFFSET + 0x4), _stack_frame, {
-    // trace!("COM1/COM3 serial handler");
+    // log::trace!("COM1/COM3 serial handler");
+
     #[cfg(target_arch = "aarch64")] {
         let mut sp = COM1_SERIAL_PORT.get().unwrap().as_ref().lock();
-        sp.enable_interrupt(SerialPortInterruptEvent::DataReceived, false);
+        sp.acknowledge_interrupt(SerialPortInterruptEvent::DataReceived);
     }
 
     if let Some(func) = INTERRUPT_ACTION_COM1_COM3.get() {
         func()
     }
+
+    // log::trace!("COM1/COM3 serial handler done");
     EoiBehaviour::HandlerDidNotSendEoi
 });
 

kernel/serial_port_basic/Cargo.toml

@@ -13,9 +13,8 @@ spin = "0.9.4"
 port_io = { path = "../../libs/port_io" }
 
 [target.'cfg(target_arch = "aarch64")'.dependencies]
-pl011 = { git = "https://github.com/theseus-os/pl011/", rev = "464dbf22" }
+uart_pl011 = { path = "../uart_pl011" }
 arm_boards = { path = "../arm_boards" }
-memory = { path = "../memory" }
 
 [lib]
 crate-type = ["rlib"]

kernel/serial_port_basic/src/aarch64.rs

@@ -1,7 +1,6 @@
-use memory::{MappedPages, PAGE_SIZE, map_frame_range, MMIO_FLAGS};
 use super::{TriState, SerialPortInterruptEvent};
 use arm_boards::BOARD_CONFIG;
-use pl011::PL011;
+use uart_pl011::Pl011;
 use core::fmt;
 
 /// The base port I/O addresses for COM serial ports.
@@ -19,11 +18,10 @@ pub enum SerialPortAddress {
 }
 
 /// A serial port and its various data and control registers.
+#[derive(Debug)]
 pub struct SerialPort {
     port_address: SerialPortAddress,
-    inner: Option<PL011>,
-    // Owner of the MMIO frames for the PL011 registers
-    _mapped_pages: Option<MappedPages>,
+    inner: Option<Pl011>,
 }
 
 impl Drop for SerialPort {
@@ -33,7 +31,6 @@ impl Drop for SerialPort {
         if let TriState::Taken = &*sp_locked {
             let dummy = SerialPort {
                 inner: None,
-                _mapped_pages: None,
                 port_address: self.port_address,
             };
             let dropped = core::mem::replace(self, dummy);
@@ -57,19 +54,12 @@ impl SerialPort {
             None => panic!("Board doesn't have {:?}", serial_port_address),
         };
 
-        let mapped_pages = map_frame_range(*mmio_base, PAGE_SIZE, MMIO_FLAGS)
-            .expect("serial_port_basic: couldn't map the UART interface");
-        let addr = mapped_pages.start_address().value();
-        let mut pl011 = PL011::new(addr as *mut _);
-
-        pl011.enable_rx_interrupt(true);
-        pl011.set_fifo_mode(false);
-        // pl011.log_status();
+        let pl011 = Pl011::new(*mmio_base)
+            .expect("SerialPort::new: Couldn't initialize PL011 UART");
 
         SerialPort {
             port_address: serial_port_address,
             inner: Some(pl011),
-            _mapped_pages: Some(mapped_pages),
         }
     }
 
@@ -84,6 +74,15 @@ impl SerialPort {
         }
     }
 
+    /// Clears an interrupt in the serial port controller
+    pub fn acknowledge_interrupt(&mut self, event: SerialPortInterruptEvent) {
+        if matches!(event, SerialPortInterruptEvent::DataReceived) {
+            self.inner.as_mut().unwrap().acknowledge_rx_interrupt();
+        } else {
+            unimplemented!()
+        }
+    }
+
     /// Write the given string to the serial port, blocking until data can be transmitted.
     ///
     /// # Special characters

kernel/serial_port_basic/src/x86_64.rs

@@ -187,6 +187,11 @@ impl SerialPort {
         }
     }
 
+    /// Clears an interrupt in the serial port controller
+    pub fn acknowledge_interrupt(&mut self, _event: SerialPortInterruptEvent) {
+        // no-op on x86_64
+    }
+
     /// Write the given string to the serial port, blocking until data can be transmitted.
     ///
     /// # Special characters

kernel/uart_pl011/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "uart_pl011"
+authors = ["Nathan Royer <[email protected]>"]
+description = "Simple Driver for PL011 UARTs"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+log = "0.4.8"
+volatile = "0.2.7"
+zerocopy = "0.5.0"
+memory = { path = "../memory" }

kernel/uart_pl011/src/lib.rs

@@ -0,0 +1,192 @@
+//! Driver for pl011 UARTs
+
+#![no_std]
+use core::fmt;
+use zerocopy::FromBytes;
+use volatile::{Volatile, ReadOnly, WriteOnly};
+use memory::{BorrowedMappedPages, Mutable, PhysicalAddress, PAGE_SIZE, map_frame_range, MMIO_FLAGS};
+
+/// Struct representing Pl011 registers. Not intended to be directly used
+#[derive(Debug, FromBytes)]
+#[repr(C)]
+pub struct Pl011_Regs {
+    /// Data Register
+    pub uartdr: Volatile<u32>,
+    /// receive status / error clear
+    pub uartrsr: Volatile<u32>,
+    reserved0: [u32; 4],
+    /// flag register
+    pub uartfr: ReadOnly<u32>,
+    reserved1: u32,
+    /// IrDA Low power counter register
+    pub uartilpr: Volatile<u32>,
+    /// integer baud rate
+    pub uartibrd: Volatile<u32>,
+    /// fractional baud rate
+    pub uartfbrd: Volatile<u32>,
+    /// line control
+    pub uartlcr_h: Volatile<u32>,
+    /// control
+    pub uartcr: Volatile<u32>,
+    /// interrupt fifo level select
+    pub uartifls: Volatile<u32>,
+    /// interrupt mask set/clear
+    pub uartimsc: Volatile<u32>,
+    /// raw interrupt status
+    pub uartris: ReadOnly<u32>,
+    /// masked interrupt status
+    pub uartmis: ReadOnly<u32>,
+    /// interrupt clear
+    pub uarticr: WriteOnly<u32>,
+    /// dma control
+    pub uartdmacr: Volatile<u32>,
+    reserved2: [u32; 997],
+    /// UART Periph ID0
+    pub uartperiphid0: ReadOnly<u32>,
+    /// UART Periph ID1
+    pub uartperiphid1: ReadOnly<u32>,
+    /// UART Periph ID2
+    pub uartperiphid2: ReadOnly<u32>,
+    /// UART Periph ID3
+    pub uartperiphid3: ReadOnly<u32>,
+    /// UART PCell ID0
+    pub uartpcellid0: ReadOnly<u32>,
+    /// UART PCell ID1
+    pub uartpcellid1: ReadOnly<u32>,
+    /// UART PCell ID2
+    pub uartpcellid2: ReadOnly<u32>,
+    /// UART PCell ID3
+    pub uartpcellid3: ReadOnly<u32>,
+}
+
+const UARTIMSC_RXIM: u32 = 1 << 4;
+const UARTUCR_RXIC: u32 = 1 << 4;
+
+const UARTLCR_FEN: u32 = 1 << 4;
+
+const UARTCR_RX_ENABLED: u32 = 1 << 9;
+const UARTCR_TX_ENABLED: u32 = 1 << 8;
+const UARTCR_UART_ENABLED: u32 = 1 << 0;
+
+const UARTFR_RX_BUF_EMPTY: u32 = 1 << 4;
+const UARTFR_TX_BUF_FULL: u32 = 1 << 5;
+
+/// A Pl011 Single-Serial-Port Controller.
+pub struct Pl011 {
+    regs: BorrowedMappedPages<Pl011_Regs, Mutable>
+}
+
+impl core::fmt::Debug for Pl011 {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        self.regs.fmt(f)
+    }
+}
+
+/// Generic methods
+impl Pl011 {
+    /// Initialize a UART driver.
+    pub fn new(base: PhysicalAddress) -> Result<Self, &'static str> {
+        let mapped_pages = map_frame_range(base, PAGE_SIZE, MMIO_FLAGS)?;
+
+        let mut this = Self {
+            regs: mapped_pages.into_borrowed_mut(0).map_err(|(_, e)| e)?,
+        };
+
+        this.enable_rx_interrupt(true);
+        this.set_fifo_mode(false);
+
+        Ok(this)
+    }
+
+    /// Enable on-receive interrupt
+    pub fn enable_rx_interrupt(&mut self, enable: bool) {
+        let mut reg = self.regs.uartimsc.read();
+
+        match enable {
+            true  => reg |=  UARTIMSC_RXIM,
+            false => reg &= !UARTIMSC_RXIM,
+        };
+
+        self.regs.uartimsc.write(reg);
+    }
+
+    pub fn acknowledge_rx_interrupt(&mut self) {
+        self.regs.uarticr.write(UARTUCR_RXIC);
+    }
+
+    /// Set FIFO mode
+    pub fn set_fifo_mode(&mut self, enable: bool) {
+        let mut reg = self.regs.uartlcr_h.read();
+
+        match enable {
+            true  => reg |=  UARTLCR_FEN,
+            false => reg &= !UARTLCR_FEN,
+        };
+
+        self.regs.uartlcr_h.write(reg);
+    }
+
+    /// Outputs a summary of the state of the controller using `log::info!()`
+    pub fn log_status(&self) {
+        let reg = self.regs.uartcr.read();
+        log::info!("RX enabled: {}", (reg & UARTCR_RX_ENABLED) > 0);
+        log::info!("TX enabled: {}", (reg & UARTCR_TX_ENABLED) > 0);
+        log::info!("UART enabled: {}", (reg & UARTCR_UART_ENABLED) > 0);
+    }
+
+    /// Returns true if the receive-buffer-empty flag is clear.
+    pub fn has_incoming_data(&self) -> bool {
+        let uartfr = self.regs.uartfr.read();
+        uartfr & UARTFR_RX_BUF_EMPTY == 0
+    }
+
+    /// Reads a single byte out the uart
+    ///
+    /// Spins until a byte is available in the fifo.
+    pub fn read_byte(&self) -> u8 {
+        while !self.has_incoming_data() {}
+        self.regs.uartdr.read() as u8
+    }
+
+    /// Reads bytes into a slice until there is none available.
+    pub fn read_bytes(&self, bytes: &mut [u8]) -> usize {
+        let mut read = 0;
+
+        while read < bytes.len() && self.has_incoming_data() {
+            bytes[read] = self.read_byte();
+            read += 1;
+        }
+
+        read
+    }
+
+    /// Returns true if the transmit-buffer-full flag is clear.
+    pub fn is_writeable(&self) -> bool {
+        let uartfr = self.regs.uartfr.read();
+        uartfr & UARTFR_TX_BUF_FULL == 0
+    }
+
+    /// Writes a single byte out the uart.
+    ///
+    /// Spins until space is available in the fifo.
+    pub fn write_byte(&mut self, data: u8) {
+        while !self.is_writeable() {}
+        self.regs.uartdr.write(data as u32);
+    }
+
+    /// Writes a byte slice out the uart.
+    ///
+    /// Spins until space is available in the fifo.
+    pub fn write_bytes(&mut self, bytes: &[u8]) {
+        for b in bytes {
+            self.write_byte(*b);
+        }
+    }
+}
+
+impl fmt::Write for Pl011 {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.write_bytes(s.as_bytes());
+        Ok(())
+    }
+}