rp/pio: add sm batch operations

sometimes state machines need to be started, restarted, or synchronized
at exactly the same time. the current interface does not allow this but
the hardware does, so let's expose that.

embassy-rp/src/pio.rs

@@ -912,6 +912,47 @@ impl<'d, PIO: Instance> Common<'d, PIO> {
             pio: PhantomData::default(),
         }
     }
+
+    pub fn apply_sm_batch(&mut self, f: impl FnOnce(&mut PioBatch<'d, PIO>)) {
+        let mut batch = PioBatch {
+            clkdiv_restart: 0,
+            sm_restart: 0,
+            sm_enable_mask: 0,
+            sm_enable: 0,
+            _pio: PhantomData,
+        };
+        f(&mut batch);
+        unsafe {
+            PIO::PIO.ctrl().modify(|w| {
+                w.set_clkdiv_restart(batch.clkdiv_restart);
+                w.set_sm_restart(batch.sm_restart);
+                w.set_sm_enable((w.sm_enable() & !batch.sm_enable_mask) | batch.sm_enable);
+            });
+        }
+    }
+}
+
+pub struct PioBatch<'a, PIO: Instance> {
+    clkdiv_restart: u8,
+    sm_restart: u8,
+    sm_enable_mask: u8,
+    sm_enable: u8,
+    _pio: PhantomData<&'a PIO>,
+}
+
+impl<'a, PIO: Instance> PioBatch<'a, PIO> {
+    pub fn restart_clockdiv<const SM: usize>(&mut self, _sm: &mut StateMachine<'a, PIO, SM>) {
+        self.clkdiv_restart |= 1 << SM;
+    }
+
+    pub fn restart<const SM: usize>(&mut self, _sm: &mut StateMachine<'a, PIO, SM>) {
+        self.clkdiv_restart |= 1 << SM;
+    }
+
+    pub fn set_enable<const SM: usize>(&mut self, _sm: &mut StateMachine<'a, PIO, SM>, enable: bool) {
+        self.sm_enable_mask |= 1 << SM;
+        self.sm_enable |= (enable as u8) << SM;
+    }
 }
 
 pub struct Irq<'d, PIO: Instance, const N: usize> {