rp/pio: wrap sm rx, tx in structs and allow splitting

this *finally* allows sound implementions of bidirectional transfers
without blocking. the futures previously allowed only a single direction
to be active at any given time, and the dma transfers didn't take a
mutable reference and were thus unsound.

examples/rp/src/bin/pio_async.rs

@@ -42,7 +42,7 @@ async fn pio_task_sm0(mut sm: PioStateMachine<'static, PIO0, 0>) {
 
     let mut v = 0x0f0caffa;
     loop {
-        sm.wait_push(v).await;
+        sm.tx().wait_push(v).await;
         v ^= 0xffff;
         info!("Pushed {:032b} to FIFO", v);
     }
@@ -70,7 +70,7 @@ fn setup_pio_task_sm1(pio: &mut PioCommon<PIO0>, sm: &mut PioStateMachine<PIO0,
 async fn pio_task_sm1(mut sm: PioStateMachine<'static, PIO0, 1>) {
     sm.set_enable(true);
     loop {
-        let rx = sm.wait_pull().await;
+        let rx = sm.rx().wait_pull().await;
         info!("Pulled {:032b} from FIFO", rx);
     }
 }

examples/rp/src/bin/pio_dma.rs

@@ -60,9 +60,10 @@ async fn main(_spawner: Spawner) {
     }
     let mut din = [0u32; 29];
     loop {
+        let (rx, tx) = sm.rx_tx();
         join(
-            sm.dma_push(dma_out_ref.reborrow(), &dout),
-            sm.dma_pull(dma_in_ref.reborrow(), &mut din),
+            tx.dma_push(dma_out_ref.reborrow(), &dout),
+            rx.dma_pull(dma_in_ref.reborrow(), &mut din),
         )
         .await;
         for i in 0..din.len() {

examples/rp/src/bin/pio_hd44780.rs

@@ -139,14 +139,14 @@ impl<'l> HD44780<'l> {
 
         sm0.set_enable(true);
         // init to 8 bit thrice
-        sm0.push_tx((50000 << 8) | 0x30);
-        sm0.push_tx((5000 << 8) | 0x30);
-        sm0.push_tx((200 << 8) | 0x30);
+        sm0.tx().push((50000 << 8) | 0x30);
+        sm0.tx().push((5000 << 8) | 0x30);
+        sm0.tx().push((200 << 8) | 0x30);
         // init 4 bit
-        sm0.push_tx((200 << 8) | 0x20);
+        sm0.tx().push((200 << 8) | 0x20);
         // set font and lines
-        sm0.push_tx((50 << 8) | 0x20);
-        sm0.push_tx(0b1100_0000);
+        sm0.tx().push((50 << 8) | 0x20);
+        sm0.tx().push(0b1100_0000);
 
         irq0.wait().await;
         sm0.set_enable(false);
@@ -216,7 +216,7 @@ impl<'l> HD44780<'l> {
         sm0.set_enable(true);
 
         // display on and cursor on and blinking, reset display
-        sm0.dma_push(dma.reborrow(), &[0x81u8, 0x0f, 1]).await;
+        sm0.tx().dma_push(dma.reborrow(), &[0x81u8, 0x0f, 1]).await;
 
         Self {
             dma: dma.map_into(),
@@ -240,6 +240,6 @@ impl<'l> HD44780<'l> {
         // set cursor to 1:15
         self.buf[38..].copy_from_slice(&[0x80, 0xcf]);
 
-        self.sm.dma_push(self.dma.reborrow(), &self.buf).await;
+        self.sm.tx().dma_push(self.dma.reborrow(), &self.buf).await;
     }
 }

examples/rp/src/bin/ws2812-pio.rs

@@ -87,7 +87,7 @@ impl<'d, P: PioInstance, const S: usize> Ws2812<'d, P, S> {
     pub async fn write(&mut self, colors: &[RGB8]) {
         for color in colors {
             let word = (u32::from(color.g) << 24) | (u32::from(color.r) << 16) | (u32::from(color.b) << 8);
-            self.sm.wait_push(word).await;
+            self.sm.tx().wait_push(word).await;
         }
     }
 }