rp/uart: report errors from buffered uart

this reports errors at the same location the blocking uart would, which
works out to being mostly exact (except in the case of overruns, where
one extra character is dropped). this is actually easier than going
nuclear in the case of errors and nuking both the buffer contents and
the rx fifo, both of which are things we'd have to do in addition to
what's added here, and neither are needed for correctness.

1 files changed, 229 insertions, 20 deletions

diff --git a/tests/rp/src/bin/uart_buffered.rs b/tests/rp/src/bin/uart_buffered.rs
index a1f0e2bf3..1deb22ce6 100644
--- a/tests/rp/src/bin/uart_buffered.rs
+++ b/tests/rp/src/bin/uart_buffered.rs
@@ -2,39 +2,248 @@
 #![no_main]
 #![feature(type_alias_impl_trait)]
 
-use defmt::{assert_eq, *};
+use defmt::{assert_eq, panic, *};
 use embassy_executor::Spawner;
+use embassy_rp::gpio::{Level, Output};
 use embassy_rp::interrupt;
-use embassy_rp::uart::{BufferedUart, Config};
-use embedded_io::asynch::{Read, Write};
+use embassy_rp::uart::{BufferedUart, BufferedUartRx, Config, Error, Instance, Parity};
+use embassy_time::{Duration, Timer};
+use embedded_io::asynch::{Read, ReadExactError, Write};
 use {defmt_rtt as _, panic_probe as _};
 
+async fn read<const N: usize>(uart: &mut BufferedUart<'_, impl Instance>) -> Result<[u8; N], Error> {
+    let mut buf = [255; N];
+    match uart.read_exact(&mut buf).await {
+        Ok(()) => Ok(buf),
+        // we should not ever produce an Eof condition
+        Err(ReadExactError::UnexpectedEof) => panic!(),
+        Err(ReadExactError::Other(e)) => Err(e),
+    }
+}
+
+async fn read1<const N: usize>(uart: &mut BufferedUartRx<'_, impl Instance>) -> Result<[u8; N], Error> {
+    let mut buf = [255; N];
+    match uart.read_exact(&mut buf).await {
+        Ok(()) => Ok(buf),
+        // we should not ever produce an Eof condition
+        Err(ReadExactError::UnexpectedEof) => panic!(),
+        Err(ReadExactError::Other(e)) => Err(e),
+    }
+}
+
+async fn send(pin: &mut Output<'_, impl embassy_rp::gpio::Pin>, v: u8, parity: Option<bool>) {
+    pin.set_low();
+    Timer::after(Duration::from_millis(1)).await;
+    for i in 0..8 {
+        if v & (1 << i) == 0 {
+            pin.set_low();
+        } else {
+            pin.set_high();
+        }
+        Timer::after(Duration::from_millis(1)).await;
+    }
+    if let Some(b) = parity {
+        if b {
+            pin.set_high();
+        } else {
+            pin.set_low();
+        }
+        Timer::after(Duration::from_millis(1)).await;
+    }
+    pin.set_high();
+    Timer::after(Duration::from_millis(1)).await;
+}
+
 #[embassy_executor::main]
 async fn main(_spawner: Spawner) {
     let p = embassy_rp::init(Default::default());
     info!("Hello World!");
 
-    let (tx, rx, uart) = (p.PIN_0, p.PIN_1, p.UART0);
+    let (mut tx, mut rx, mut uart) = (p.PIN_0, p.PIN_1, p.UART0);
+    let mut irq = interrupt::take!(UART0_IRQ);
+
+    {
+        let config = Config::default();
+        let tx_buf = &mut [0u8; 16];
+        let rx_buf = &mut [0u8; 16];
+        let mut uart = BufferedUart::new(&mut uart, &mut irq, &mut tx, &mut rx, tx_buf, rx_buf, config);
+
+        // Make sure we send more bytes than fits in the FIFO, to test the actual
+        // bufferedUart.
+
+        let data = [
+            1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
+            30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
+        ];
+        uart.write_all(&data).await.unwrap();
+        info!("Done writing");
+
+        assert_eq!(read(&mut uart).await.unwrap(), data);
+    }
+
+    info!("test overflow detection");
+    {
+        let config = Config::default();
+        let tx_buf = &mut [0u8; 16];
+        let rx_buf = &mut [0u8; 16];
+        let mut uart = BufferedUart::new(&mut uart, &mut irq, &mut tx, &mut rx, tx_buf, rx_buf, config);
+
+        // Make sure we send more bytes than fits in the FIFO, to test the actual
+        // bufferedUart.
+
+        let data = [
+            1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
+            30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
+        ];
+        let overflow = [
+            101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116,
+        ];
+        // give each block time to settle into the fifo. we want the overrun to occur at a well-defined point.
+        uart.write_all(&data).await.unwrap();
+        uart.blocking_flush().unwrap();
+        while uart.busy() {}
+        uart.write_all(&overflow).await.unwrap();
+        uart.blocking_flush().unwrap();
+        while uart.busy() {}
+
+        // already buffered/fifod prefix is valid
+        assert_eq!(read(&mut uart).await.unwrap(), data);
+        // next received character causes overrun error and is discarded
+        uart.write_all(&[1, 2, 3]).await.unwrap();
+        uart.blocking_flush().unwrap();
+        assert_eq!(read::<1>(&mut uart).await.unwrap_err(), Error::Overrun);
+        assert_eq!(read(&mut uart).await.unwrap(), [2, 3]);
+    }
+
+    info!("test break detection");
+    {
+        let mut config = Config::default();
+        config.baudrate = 1000;
+        let tx_buf = &mut [0u8; 16];
+        let rx_buf = &mut [0u8; 16];
+        let mut uart = BufferedUart::new(&mut uart, &mut irq, &mut tx, &mut rx, tx_buf, rx_buf, config);
+
+        // break on empty buffer
+        uart.send_break(20).await;
+        assert_eq!(read::<1>(&mut uart).await.unwrap_err(), Error::Break);
+        uart.write_all(&[64]).await.unwrap();
+        assert_eq!(read(&mut uart).await.unwrap(), [64]);
+
+        // break on partially filled buffer
+        uart.write_all(&[65; 2]).await.unwrap();
+        uart.send_break(20).await;
+        uart.write_all(&[66]).await.unwrap();
+        assert_eq!(read(&mut uart).await.unwrap(), [65; 2]);
+        assert_eq!(read::<1>(&mut uart).await.unwrap_err(), Error::Break);
+        assert_eq!(read(&mut uart).await.unwrap(), [66]);
+
+        // break on full buffer
+        uart.write_all(&[64; 16]).await.unwrap();
+        uart.send_break(20).await;
+        uart.write_all(&[65]).await.unwrap();
+        assert_eq!(read(&mut uart).await.unwrap(), [64; 16]);
+        assert_eq!(read::<1>(&mut uart).await.unwrap_err(), Error::Break);
+        assert_eq!(read(&mut uart).await.unwrap(), [65]);
+    }
+
+    // parity detection. here we bitbang to not require two uarts.
+    info!("test parity error detection");
+    {
+        let mut pin = Output::new(&mut tx, Level::High);
+        // choose a very slow baud rate to make tests reliable even with O0
+        let mut config = Config::default();
+        config.baudrate = 1000;
+        config.parity = Parity::ParityEven;
+        let rx_buf = &mut [0u8; 16];
+        let mut uart = BufferedUartRx::new(&mut uart, &mut irq, &mut rx, rx_buf, config);
+
+        async fn chr(pin: &mut Output<'_, impl embassy_rp::gpio::Pin>, v: u8, parity: u32) {
+            send(pin, v, Some(parity != 0)).await;
+        }
+
+        // first check that we can send correctly
+        chr(&mut pin, 64, 1).await;
+        assert_eq!(read1(&mut uart).await.unwrap(), [64]);
+
+        // parity on empty buffer
+        chr(&mut pin, 64, 0).await;
+        chr(&mut pin, 4, 1).await;
+        assert_eq!(read1::<1>(&mut uart).await.unwrap_err(), Error::Parity);
+        assert_eq!(read1(&mut uart).await.unwrap(), [4]);
+
+        // parity on partially filled buffer
+        chr(&mut pin, 64, 1).await;
+        chr(&mut pin, 32, 1).await;
+        chr(&mut pin, 64, 0).await;
+        chr(&mut pin, 65, 0).await;
+        assert_eq!(read1(&mut uart).await.unwrap(), [64, 32]);
+        assert_eq!(read1::<1>(&mut uart).await.unwrap_err(), Error::Parity);
+        assert_eq!(read1(&mut uart).await.unwrap(), [65]);
+
+        // parity on full buffer
+        for i in 0..16 {
+            chr(&mut pin, i, i.count_ones() % 2).await;
+        }
+        chr(&mut pin, 64, 0).await;
+        chr(&mut pin, 65, 0).await;
+        assert_eq!(
+            read1(&mut uart).await.unwrap(),
+            [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
+        );
+        assert_eq!(read1::<1>(&mut uart).await.unwrap_err(), Error::Parity);
+        assert_eq!(read1(&mut uart).await.unwrap(), [65]);
+    }
+
+    // framing error detection. here we bitbang because there's no other way.
+    info!("test framing error detection");
+    {
+        let mut pin = Output::new(&mut tx, Level::High);
+        // choose a very slow baud rate to make tests reliable even with O0
+        let mut config = Config::default();
+        config.baudrate = 1000;
+        let rx_buf = &mut [0u8; 16];
+        let mut uart = BufferedUartRx::new(&mut uart, &mut irq, &mut rx, rx_buf, config);
+
+        async fn chr(pin: &mut Output<'_, impl embassy_rp::gpio::Pin>, v: u8, good: bool) {
+            if good {
+                send(pin, v, None).await;
+            } else {
+                send(pin, v, Some(false)).await;
+            }
+        }
 
-    let config = Config::default();
-    let irq = interrupt::take!(UART0_IRQ);
-    let tx_buf = &mut [0u8; 16];
-    let rx_buf = &mut [0u8; 16];
-    let mut uart = BufferedUart::new(uart, irq, tx, rx, tx_buf, rx_buf, config);
+        // first check that we can send correctly
+        chr(&mut pin, 64, true).await;
+        assert_eq!(read1(&mut uart).await.unwrap(), [64]);
 
-    // Make sure we send more bytes than fits in the FIFO, to test the actual
-    // bufferedUart.
+        // framing on empty buffer
+        chr(&mut pin, 64, false).await;
+        assert_eq!(read1::<1>(&mut uart).await.unwrap_err(), Error::Framing);
+        chr(&mut pin, 65, true).await;
+        assert_eq!(read1(&mut uart).await.unwrap(), [65]);
 
-    let data = [
-        1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
-        31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
-    ];
-    uart.write_all(&data).await.unwrap();
-    info!("Done writing");
+        // framing on partially filled buffer
+        chr(&mut pin, 64, true).await;
+        chr(&mut pin, 32, true).await;
+        chr(&mut pin, 64, false).await;
+        chr(&mut pin, 65, true).await;
+        assert_eq!(read1(&mut uart).await.unwrap(), [64, 32]);
+        assert_eq!(read1::<1>(&mut uart).await.unwrap_err(), Error::Framing);
+        assert_eq!(read1(&mut uart).await.unwrap(), [65]);
 
-    let mut buf = [0; 48];
-    uart.read_exact(&mut buf).await.unwrap();
-    assert_eq!(buf, data);
+        // framing on full buffer
+        for i in 0..16 {
+            chr(&mut pin, i, true).await;
+        }
+        chr(&mut pin, 64, false).await;
+        chr(&mut pin, 65, true).await;
+        assert_eq!(
+            read1(&mut uart).await.unwrap(),
+            [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
+        );
+        assert_eq!(read1::<1>(&mut uart).await.unwrap_err(), Error::Framing);
+        assert_eq!(read1(&mut uart).await.unwrap(), [65]);
+    }
 
     info!("Test OK");
     cortex_m::asm::bkpt();