stm32/hrtim: impl. draft frequency computation

1 files changed, 135 insertions, 3 deletions

diff --git a/embassy-stm32/src/timer/mod.rs b/embassy-stm32/src/timer/mod.rs
index 34ad5db11..03b9b3cf8 100644
--- a/embassy-stm32/src/timer/mod.rs
+++ b/embassy-stm32/src/timer/mod.rs
@@ -1,3 +1,6 @@
+#[cfg(hrtim_v1)]
+use core::ops;
+
 use stm32_metapac::timer::vals;
 
 use crate::interrupt;
@@ -50,13 +53,64 @@ pub(crate) mod sealed {
 
         fn regs_highres() -> crate::pac::hrtim::Hrtim;
 
+        fn set_master_frequency(&mut self, frequency: Hertz);
+
+        fn set_channel_frequency(&mut self, channel: usize, frequency: Hertz);
+
         fn start(&mut self);
 
         fn stop(&mut self);
 
         fn reset(&mut self);
+    }
+}
 
-        fn set_frequency(&mut self, frequency: Hertz);
+#[cfg(hrtim_v1)]
+#[derive(Clone, Copy)]
+pub(crate) enum HighResolutionControlPrescaler {
+    Div1,
+    Div2,
+    Div4,
+    Div8,
+    Div16,
+    Div32,
+    Div64,
+    Div128,
+}
+
+#[cfg(hrtim_v1)]
+impl ops::Div<HighResolutionControlPrescaler> for Hertz {
+    type Output = Hertz;
+
+    fn div(self, rhs: HighResolutionControlPrescaler) -> Self::Output {
+        let divisor = match rhs {
+            HighResolutionControlPrescaler::Div1 => 1,
+            HighResolutionControlPrescaler::Div2 => 2,
+            HighResolutionControlPrescaler::Div4 => 4,
+            HighResolutionControlPrescaler::Div8 => 8,
+            HighResolutionControlPrescaler::Div16 => 16,
+            HighResolutionControlPrescaler::Div32 => 32,
+            HighResolutionControlPrescaler::Div64 => 64,
+            HighResolutionControlPrescaler::Div128 => 128,
+        };
+
+        Hertz(self.0 / divisor)
+    }
+}
+
+#[cfg(hrtim_v1)]
+impl From<HighResolutionControlPrescaler> for u8 {
+    fn from(val: HighResolutionControlPrescaler) -> Self {
+        match val {
+            HighResolutionControlPrescaler::Div1 => 0b000,
+            HighResolutionControlPrescaler::Div2 => 0b001,
+            HighResolutionControlPrescaler::Div4 => 0b010,
+            HighResolutionControlPrescaler::Div8 => 0b011,
+            HighResolutionControlPrescaler::Div16 => 0b100,
+            HighResolutionControlPrescaler::Div32 => 0b101,
+            HighResolutionControlPrescaler::Div64 => 0b110,
+            HighResolutionControlPrescaler::Div128 => 0b111,
+        }
     }
 }
 
@@ -235,13 +289,91 @@ foreach_interrupt! {
                 crate::pac::$inst
             }
 
+            fn set_master_frequency(&mut self, frequency: Hertz) {
+                use crate::rcc::sealed::RccPeripheral;
+
+                // TODO: fix frequency source
+                let f = frequency.0;
+                let timer_f = Self::frequency().0;
+                // Ratio taken from RM0364 Table 81
+                let base_f = Hertz(timer_f * (70_300 / 144_000_000));
+
+                /*
+                    Find the smallest prescaler that allows us to acheive our frequency
+                */
+                let psc = [
+                    HighResolutionControlPrescaler::Div1,
+                    HighResolutionControlPrescaler::Div2,
+                    HighResolutionControlPrescaler::Div4,
+                    HighResolutionControlPrescaler::Div8,
+                    HighResolutionControlPrescaler::Div16,
+                    HighResolutionControlPrescaler::Div32,
+                    HighResolutionControlPrescaler::Div64,
+                    HighResolutionControlPrescaler::Div128,
+                ]
+                .iter()
+                .skip_while(|psc| frequency < base_f / **psc)
+                .next()
+                .unwrap();
+
+                let psc_timer_f = Hertz(timer_f) / *psc;
+                let per: u16 = (psc_timer_f / f).0 as u16;
+
+                let regs = Self::regs_highres();
+
+                regs.mcr().modify(|w| w.set_ckpsc(((*psc).into())));
+                regs.mper().modify(|w| w.set_mper(per));
+
+                // regs.cr1().modify(|r| r.set_urs(vals::Urs::COUNTERONLY));
+                // regs.egr().write(|r| r.set_ug(true));
+                // regs.cr1().modify(|r| r.set_urs(vals::Urs::ANYEVENT));
+            }
+
+            fn set_channel_frequency(&mut self, channel: usize, frequency: Hertz) {
+                use crate::rcc::sealed::RccPeripheral;
+
+                // TODO: fix frequency source
+                let f = frequency.0;
+                let timer_f = Self::frequency().0;
+                // Ratio taken from RM0364 Table 81
+                let base_f = Hertz(timer_f * (70_300 / 144_000_000));
+
+                /*
+                    Find the smallest prescaler that allows us to acheive our frequency
+                */
+                let psc = [
+                    HighResolutionControlPrescaler::Div1,
+                    HighResolutionControlPrescaler::Div2,
+                    HighResolutionControlPrescaler::Div4,
+                    HighResolutionControlPrescaler::Div8,
+                    HighResolutionControlPrescaler::Div16,
+                    HighResolutionControlPrescaler::Div32,
+                    HighResolutionControlPrescaler::Div64,
+                    HighResolutionControlPrescaler::Div128,
+                ]
+                .iter()
+                .skip_while(|psc| frequency < base_f / **psc)
+                .next()
+                .unwrap();
+
+                let psc_timer_f = Hertz(timer_f) / *psc;
+                let per: u16 = (psc_timer_f / f).0 as u16;
+
+                let regs = Self::regs_highres();
+
+                regs.tim(channel).cr().modify(|w| w.set_ckpsc(((*psc).into())));
+                regs.tim(channel).per().modify(|w| w.set_per(per));
+
+                // regs.cr1().modify(|r| r.set_urs(vals::Urs::COUNTERONLY));
+                // regs.egr().write(|r| r.set_ug(true));
+                // regs.cr1().modify(|r| r.set_urs(vals::Urs::ANYEVENT));
+            }
+
             fn start(&mut self) { todo!() }
 
             fn stop(&mut self) { todo!() }
 
             fn reset(&mut self) { todo!() }
-
-            fn set_frequency(&mut self, frequency: Hertz) { todo!() }
         }
 
         impl HighResolutionControlInstance for crate::peripherals::$inst {