RP235x: First stab at support for new FIFO options

embassy-rp/src/pio/mod.rs

@@ -50,6 +50,18 @@ pub enum FifoJoin {
     RxOnly,
     /// Tx fifo twice as deep. RX fifo disabled
     TxOnly,
+    /// Enable random writes (`FJOIN_RX_PUT`) from the state machine (through ISR),
+    /// and random reads from the system (using [`StateMachine::get_rxf_entry`]).
+    #[cfg(feature = "_rp235x")]
+    RxAsStatus,
+    /// Enable random reads (`FJOIN_RX_GET`) from the state machine (through OSR),
+    /// and random writes from the system (using [`StateMachine::set_rxf_entry`]).
+    #[cfg(feature = "_rp235x")]
+    RxAsControl,
+    /// FJOIN_RX_PUT | FJOIN_RX_GET: RX can be used as a scratch register,
+    /// not accesible from the CPU
+    #[cfg(feature = "_rp235x")]
+    PioScratch,
 }
 
 /// Shift direction.
@@ -730,6 +742,17 @@ impl<'d, PIO: Instance + 'd, const SM: usize> StateMachine<'d, PIO, SM> {
             w.set_in_shiftdir(config.shift_in.direction == ShiftDirection::Right);
             w.set_autopull(config.shift_out.auto_fill);
             w.set_autopush(config.shift_in.auto_fill);
+
+            #[cfg(feature = "_rp235x")]
+            {
+                w.set_fjoin_rx_get(
+                    config.fifo_join == FifoJoin::RxAsControl || config.fifo_join == FifoJoin::PioScratch,
+                );
+                w.set_fjoin_rx_put(
+                    config.fifo_join == FifoJoin::RxAsStatus || config.fifo_join == FifoJoin::PioScratch,
+                );
+                w.set_in_count(config.in_count);
+            }
         });
 
         #[cfg(feature = "rp2040")]
@@ -907,6 +930,20 @@ impl<'d, PIO: Instance + 'd, const SM: usize> StateMachine<'d, PIO, SM> {
     pub fn rx_tx(&mut self) -> (&mut StateMachineRx<'d, PIO, SM>, &mut StateMachineTx<'d, PIO, SM>) {
         (&mut self.rx, &mut self.tx)
     }
+
+    /// Return the contents of the nth entry of the RX FIFO
+    /// (should be used only when the FIFO config is set to [`FifoJoin::RxAsStatus`])
+    #[cfg(feature = "_rp235x")]
+    pub fn get_rxf_entry(&self, n: usize) -> u32 {
+        PIO::PIO.rxf_putget(SM).putget(n).read()
+    }
+
+    /// Set the contents of the nth entry of the RX FIFO
+    /// (should be used only when the FIFO config is set to [`FifoJoin::RxAsControl`])
+    #[cfg(feature = "_rp235x")]
+    pub fn set_rxf_entry(&self, n: usize, val: u32) {
+        PIO::PIO.rxf_putget(SM).putget(n).write_value(val)
+    }
 }
 
 /// PIO handle.