From a9074fd09bb2fa6265808f32e5cf303285fc0ec6 Mon Sep 17 00:00:00 2001
From: pennae <github@quasiparticle.net>
Date: Tue, 25 Apr 2023 18:47:51 +0200
Subject: [PATCH] rp/pio: enable pio interrupts only once

since we never actually *disable* these interrupts for any length of
time we can simply enable them globally. we also initialize all pio
interrupt flags to not cause system interrupts since state machine
irqa are not necessarily meant to cause a system interrupt when set. the
fifo interrupts are sticky and can likewise only be cleared inside the
handler by disabling them.
---
 embassy-rp/src/lib.rs |  1 +
 embassy-rp/src/pio.rs | 50 ++++++++++++-------------------------------
 2 files changed, 15 insertions(+), 36 deletions(-)

diff --git a/embassy-rp/src/lib.rs b/embassy-rp/src/lib.rs
index 697f4308..d69d12a3 100644
--- a/embassy-rp/src/lib.rs
+++ b/embassy-rp/src/lib.rs
@@ -156,6 +156,7 @@ pub fn init(_config: config::Config) -> Peripherals {
         #[cfg(feature = "time-driver")]
         timer::init();
         dma::init();
+        pio::init();
     }
 
     peripherals
diff --git a/embassy-rp/src/pio.rs b/embassy-rp/src/pio.rs
index f0d550d9..00a7aa37 100644
--- a/embassy-rp/src/pio.rs
+++ b/embassy-rp/src/pio.rs
@@ -79,6 +79,20 @@ unsafe fn PIO1_IRQ_0() {
     pac::PIO1.irqs(0).inte().write_clear(|m| m.0 = ints);
 }
 
+pub(crate) unsafe fn init() {
+    let irq = interrupt::PIO0_IRQ_0::steal();
+    irq.disable();
+    irq.set_priority(interrupt::Priority::P3);
+    pac::PIO0.irqs(0).inte().write(|m| m.0 = 0);
+    irq.enable();
+
+    let irq = interrupt::PIO1_IRQ_0::steal();
+    irq.disable();
+    irq.set_priority(interrupt::Priority::P3);
+    pac::PIO1.irqs(0).inte().write(|m| m.0 = 0);
+    irq.enable();
+}
+
 /// Future that waits for TX-FIFO to become writable
 #[must_use = "futures do nothing unless you `.await` or poll them"]
 pub struct FifoOutFuture<'a, PIO: PioInstance, SM: PioStateMachine + Unpin> {
@@ -89,14 +103,6 @@ pub struct FifoOutFuture<'a, PIO: PioInstance, SM: PioStateMachine + Unpin> {
 
 impl<'a, PIO: PioInstance, SM: PioStateMachine + Unpin> FifoOutFuture<'a, PIO, SM> {
     pub fn new(sm: &'a mut SM, value: u32) -> Self {
-        unsafe {
-            critical_section::with(|_| {
-                let irq = PIO::Irq::steal();
-                irq.set_priority(interrupt::Priority::P3);
-
-                irq.enable();
-            });
-        }
         FifoOutFuture {
             sm,
             pio: PhantomData::default(),
@@ -115,12 +121,9 @@ impl<'d, PIO: PioInstance, SM: PioStateMachine + Unpin> Future for FifoOutFuture
         } else {
             WAKERS[PIO::PIO_NO as usize].fifo_out()[SM::Sm::SM_NO as usize].register(cx.waker());
             unsafe {
-                let irq = PIO::Irq::steal();
-                irq.disable();
                 PIOS[PIO::PIO_NO as usize].irqs(0).inte().write_set(|m| {
                     m.0 = TXNFULL_MASK << SM::Sm::SM_NO;
                 });
-                irq.enable();
             }
             // debug!("Pending");
             Poll::Pending
@@ -147,14 +150,6 @@ pub struct FifoInFuture<'a, PIO: PioInstance, SM: PioStateMachine> {
 
 impl<'a, PIO: PioInstance, SM: PioStateMachine> FifoInFuture<'a, PIO, SM> {
     pub fn new(sm: &'a mut SM) -> Self {
-        unsafe {
-            critical_section::with(|_| {
-                let irq = PIO::Irq::steal();
-                irq.set_priority(interrupt::Priority::P3);
-
-                irq.enable();
-            });
-        }
         FifoInFuture {
             sm,
             pio: PhantomData::default(),
@@ -171,12 +166,9 @@ impl<'d, PIO: PioInstance, SM: PioStateMachine> Future for FifoInFuture<'d, PIO,
         } else {
             WAKERS[PIO::PIO_NO as usize].fifo_in()[SM::Sm::SM_NO as usize].register(cx.waker());
             unsafe {
-                let irq = PIO::Irq::steal();
-                irq.disable();
                 PIOS[PIO::PIO_NO as usize].irqs(0).inte().write_set(|m| {
                     m.0 = RXNEMPTY_MASK << SM::Sm::SM_NO;
                 });
-                irq.enable();
             }
             //debug!("Pending");
             Poll::Pending
@@ -203,14 +195,6 @@ pub struct IrqFuture<PIO: PioInstance> {
 
 impl<'a, PIO: PioInstance> IrqFuture<PIO> {
     pub fn new(irq_no: u8) -> Self {
-        unsafe {
-            critical_section::with(|_| {
-                let irq = PIO::Irq::steal();
-                irq.set_priority(interrupt::Priority::P3);
-
-                irq.enable();
-            });
-        }
         IrqFuture {
             pio: PhantomData::default(),
             irq_no,
@@ -240,12 +224,9 @@ impl<'d, PIO: PioInstance> Future for IrqFuture<PIO> {
 
         WAKERS[PIO::PIO_NO as usize].irq()[self.irq_no as usize].register(cx.waker());
         unsafe {
-            let irq = PIO::Irq::steal();
-            irq.disable();
             PIOS[PIO::PIO_NO as usize].irqs(0).inte().write_set(|m| {
                 m.0 = SMIRQ_MASK << self.irq_no;
             });
-            irq.enable();
         }
         Poll::Pending
     }
@@ -1171,17 +1152,14 @@ pub struct PioInstanceBase<const PIO_NO: u8> {}
 
 pub trait PioInstance: Unpin {
     const PIO_NO: u8;
-    type Irq: Interrupt;
 }
 
 impl PioInstance for PioInstanceBase<0> {
     const PIO_NO: u8 = 0;
-    type Irq = interrupt::PIO0_IRQ_0;
 }
 
 impl PioInstance for PioInstanceBase<1> {
     const PIO_NO: u8 = 1;
-    type Irq = interrupt::PIO1_IRQ_0;
 }
 
 pub type Pio0 = PioInstanceBase<0>;