From 561126b0d6068d189477af18461bf1e467532516 Mon Sep 17 00:00:00 2001
From: Dion Dokter <diondokter@gmail.com>
Date: Sun, 1 Oct 2023 23:09:01 +0200
Subject: [PATCH] stm32: Add the ability to center-align timers

---
 embassy-stm32/src/timer/complementary_pwm.rs |  6 ++-
 embassy-stm32/src/timer/mod.rs               | 49 +++++++++++++++++++-
 embassy-stm32/src/timer/simple_pwm.rs        |  6 ++-
 3 files changed, 55 insertions(+), 6 deletions(-)

diff --git a/embassy-stm32/src/timer/complementary_pwm.rs b/embassy-stm32/src/timer/complementary_pwm.rs
index 4f033e3a..bfe5137e 100644
--- a/embassy-stm32/src/timer/complementary_pwm.rs
+++ b/embassy-stm32/src/timer/complementary_pwm.rs
@@ -57,11 +57,12 @@ impl<'d, T: ComplementaryCaptureCompare16bitInstance> ComplementaryPwm<'d, T> {
         _ch4: Option<PwmPin<'d, T, Ch4>>,
         _ch4n: Option<ComplementaryPwmPin<'d, T, Ch4>>,
         freq: Hertz,
+        counting_mode: CountingMode,
     ) -> Self {
-        Self::new_inner(tim, freq)
+        Self::new_inner(tim, freq, counting_mode)
     }
 
-    fn new_inner(tim: impl Peripheral<P = T> + 'd, freq: Hertz) -> Self {
+    fn new_inner(tim: impl Peripheral<P = T> + 'd, freq: Hertz, counting_mode: CountingMode) -> Self {
         into_ref!(tim);
 
         T::enable();
@@ -70,6 +71,7 @@ impl<'d, T: ComplementaryCaptureCompare16bitInstance> ComplementaryPwm<'d, T> {
         let mut this = Self { inner: tim };
 
         this.inner.set_frequency(freq);
+        this.inner.set_counting_mode(counting_mode);
         this.inner.start();
 
         this.inner.enable_outputs(true);
diff --git a/embassy-stm32/src/timer/mod.rs b/embassy-stm32/src/timer/mod.rs
index d88fbcfd..52d1dc11 100644
--- a/embassy-stm32/src/timer/mod.rs
+++ b/embassy-stm32/src/timer/mod.rs
@@ -75,8 +75,16 @@ pub(crate) mod sealed {
     pub trait GeneralPurpose16bitInstance: Basic16bitInstance {
         fn regs_gp16() -> crate::pac::timer::TimGp16;
 
-        fn set_count_direction(&mut self, direction: vals::Dir) {
-            Self::regs_gp16().cr1().modify(|r| r.set_dir(direction));
+        fn set_counting_mode(&mut self, mode: CountingMode) {
+            let (cms, dir) = mode.values();
+
+            let timer_enabled = Self::regs().cr1().read().cen();
+            // Changing from edge aligned to center aligned (and vice versa) is not allowed while the timer is running.
+            // Changing direction is discouraged while the timer is running.
+            assert!(timer_enabled);
+
+            Self::regs_gp16().cr1().modify(|r| r.set_dir(dir));
+            Self::regs_gp16().cr1().modify(|r| r.set_cms(cms))
         }
 
         fn set_clock_division(&mut self, ckd: vals::Ckd) {
@@ -265,6 +273,43 @@ impl From<InputTISelection> for stm32_metapac::timer::vals::CcmrInputCcs {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub enum CountingMode {
+    #[default]
+    /// The timer counts up to the reload value and then resets back to 0.
+    EdgeAlignedUp,
+    /// The timer counts down to 0 and then resets back to the reload value.
+    EdgeAlignedDown,
+    /// The timer counts up to the reload value and then counts back to 0.
+    ///
+    /// The output compare interrupt flags of channels configured in output are
+    /// set when the counter is counting down.
+    CenterAlignedDownInterrupts,
+    /// The timer counts up to the reload value and then counts back to 0.
+    ///
+    /// The output compare interrupt flags of channels configured in output are
+    /// set when the counter is counting up.
+    CenterAlignedUpInterrupts,
+    /// The timer counts up to the reload value and then counts back to 0.
+    ///
+    /// The output compare interrupt flags of channels configured in output are
+    /// set when the counter is counting both up or down.
+    CenterAlignedBothInterrupts,
+}
+
+impl CountingMode {
+    /// Get the register values to set the timer mode to the current variant
+    pub fn values(&self) -> (vals::Cms, vals::Dir) {
+        match self {
+            CountingMode::EdgeAlignedUp => (vals::Cms::EDGEALIGNED, vals::Dir::UP),
+            CountingMode::EdgeAlignedDown => (vals::Cms::EDGEALIGNED, vals::Dir::DOWN),
+            CountingMode::CenterAlignedDownInterrupts => (vals::Cms::CENTERALIGNED1, vals::Dir::UP),
+            CountingMode::CenterAlignedUpInterrupts => (vals::Cms::CENTERALIGNED2, vals::Dir::UP),
+            CountingMode::CenterAlignedBothInterrupts => (vals::Cms::CENTERALIGNED3, vals::Dir::UP),
+        }
+    }
+}
+
 #[derive(Clone, Copy)]
 pub enum OutputCompareMode {
     Frozen,
diff --git a/embassy-stm32/src/timer/simple_pwm.rs b/embassy-stm32/src/timer/simple_pwm.rs
index 9e28878b..cdf12189 100644
--- a/embassy-stm32/src/timer/simple_pwm.rs
+++ b/embassy-stm32/src/timer/simple_pwm.rs
@@ -56,11 +56,12 @@ impl<'d, T: CaptureCompare16bitInstance> SimplePwm<'d, T> {
         _ch3: Option<PwmPin<'d, T, Ch3>>,
         _ch4: Option<PwmPin<'d, T, Ch4>>,
         freq: Hertz,
+        counting_mode: CountingMode,
     ) -> Self {
-        Self::new_inner(tim, freq)
+        Self::new_inner(tim, freq, counting_mode)
     }
 
-    fn new_inner(tim: impl Peripheral<P = T> + 'd, freq: Hertz) -> Self {
+    fn new_inner(tim: impl Peripheral<P = T> + 'd, freq: Hertz, counting_mode: CountingMode) -> Self {
         into_ref!(tim);
 
         T::enable();
@@ -69,6 +70,7 @@ impl<'d, T: CaptureCompare16bitInstance> SimplePwm<'d, T> {
         let mut this = Self { inner: tim };
 
         this.inner.set_frequency(freq);
+        this.inner.set_counting_mode(counting_mode);
         this.inner.start();
 
         this.inner.enable_outputs(true);