Assume tim2 in macro and remove clock setup in chip specific rcc init

Add temporary start_tim2() fn to Clock to assist macro in starting
embassy clock

embassy-macros/src/chip/stm32.rs

@@ -9,10 +9,14 @@ pub fn generate(embassy_prefix: &ModulePrefix, config: syn::Expr) -> TokenStream
     quote!(
         use #embassy_stm32_path::{interrupt, peripherals, clock::Clock, time::Hertz};
 
-        let (p, mut c) = #embassy_stm32_path::init(#config);
+        let p = #embassy_stm32_path::init(#config);
 
+        let mut c = Clock::new(
+            unsafe { <peripherals::TIM2 as embassy::util::Steal>::steal() },
+            interrupt::take!(TIM2),
+        );
         let clock = unsafe { make_static(&mut c) };
-        clock.start();
+        clock.start_tim2();
 
         let mut alarm = clock.alarm1();
         unsafe { #embassy_path::time::set_clock(clock) };

embassy-stm32/src/clock.rs

@@ -33,6 +33,20 @@ fn calc_now(period: u32, counter: u16) -> u64 {
     ((period as u64) << 15) + ((counter as u32 ^ ((period & 1) << 15)) as u64)
 }
 
+static mut CLOCK_FREQS: Option<ClockFreqs> = None;
+
+#[derive(Copy, Clone)]
+pub struct ClockFreqs {
+    pub tim2: Hertz,
+}
+
+/// Sets the clock frequencies
+///
+/// Safety: Sets a mutable global.
+pub unsafe fn set_freqs(freqs: ClockFreqs) {
+    CLOCK_FREQS.replace(freqs);
+}
+
 struct AlarmState {
     timestamp: Cell<u64>,
     #[allow(clippy::type_complexity)]
@@ -59,8 +73,6 @@ const ALARM_COUNT: usize = 3;
 pub struct Clock<T: Instance> {
     _inner: T,
     irq: T::Interrupt,
-    /// Clock frequency
-    frequency: Hertz,
     /// Number of 2^23 periods elapsed since boot.
     period: AtomicU32,
     /// Timestamp at which to fire alarm. u64::MAX if no alarm is scheduled.
@@ -68,23 +80,37 @@ pub struct Clock<T: Instance> {
 }
 
 impl<T: Instance> Clock<T> {
-    pub fn new(peripheral: T, irq: T::Interrupt, frequency: Hertz) -> Self {
+    pub fn new(peripheral: T, irq: T::Interrupt) -> Self {
         Self {
             _inner: peripheral,
             irq,
-            frequency,
             period: AtomicU32::new(0),
             alarms: Mutex::new([AlarmState::new(), AlarmState::new(), AlarmState::new()]),
         }
     }
 
-    pub fn start(&'static self) {
+    // TODO: Temporary until clock code generation is in place
+    pub fn start_tim2(&'static self) {
+        #[cfg(feature = "_stm32l0")]
+        unsafe {
+            let rcc = crate::pac::RCC;
+            rcc.apb1enr()
+                .modify(|w| w.set_tim2en(crate::pac::rcc::vals::Lptimen::ENABLED));
+            rcc.apb1rstr().modify(|w| w.set_tim2rst(true));
+            rcc.apb1rstr().modify(|w| w.set_tim2rst(false));
+        }
+
+        let timer_freq = unsafe { CLOCK_FREQS.unwrap().tim2 };
+        self.start(timer_freq);
+    }
+
+    pub fn start(&'static self, timer_freq: Hertz) {
         let inner = T::inner();
 
         // NOTE(unsafe) Critical section to use the unsafe methods
         critical_section::with(|_| {
             unsafe {
-                inner.prepare(self.frequency);
+                inner.prepare(timer_freq);
             }
 
             self.irq.set_handler_context(self as *const _ as *mut _);

embassy-stm32/src/lib.rs

@@ -36,7 +36,6 @@ pub mod time;
 
 pub use embassy_macros::interrupt;
 pub use pac::{interrupt, peripherals, Peripherals};
-pub use rcc::SystemClock;
 
 // workaround for svd2rust-generated code using `use crate::generic::*;`
 pub(crate) use pac::regs::generic;
@@ -61,12 +60,14 @@ impl Default for Config {
 }
 
 /// Initialize embassy.
-pub fn init(config: Config) -> (Peripherals, SystemClock) {
+pub fn init(config: Config) -> Peripherals {
     let p = Peripherals::take();
 
     unsafe {
         dma::init();
         pac::init_exti();
-        (p, rcc::init(config.rcc))
+        rcc::init(config.rcc);
     }
+
+    p
 }

embassy-stm32/src/rcc/h7/mod.rs

@@ -529,5 +529,4 @@ impl<'d> Rcc<'d> {
 }
 
 // TODO
-pub type SystemClock = ();
-pub unsafe fn init(_config: Config) -> SystemClock {}
+pub unsafe fn init(_config: Config) {}

embassy-stm32/src/rcc/l0/mod.rs

@@ -1,4 +1,5 @@
 use crate::clock::Clock;
+use crate::clock::{set_freqs, ClockFreqs};
 use crate::interrupt;
 use crate::pac;
 use crate::pac::peripherals::{self, RCC, TIM2};
@@ -585,10 +586,7 @@ pub struct MCOEnabled(());
 #[derive(Clone, Copy)]
 pub struct LSE(());
 
-// We use TIM2 as SystemClock
-pub type SystemClock = Clock<TIM2>;
-
-pub unsafe fn init(config: Config) -> SystemClock {
+pub unsafe fn init(config: Config) {
     let rcc = pac::RCC;
     let enabled = vals::Iophen::ENABLED;
     rcc.iopenr().write(|w| {
@@ -602,14 +600,7 @@ pub unsafe fn init(config: Config) -> SystemClock {
 
     let mut r = <peripherals::RCC as embassy::util::Steal>::steal();
     let clocks = r.freeze(config);
-
-    rcc.apb1enr().modify(|w| w.set_tim2en(Lptimen::ENABLED));
-    rcc.apb1rstr().modify(|w| w.set_tim2rst(true));
-    rcc.apb1rstr().modify(|w| w.set_tim2rst(false));
-
-    Clock::new(
-        <peripherals::TIM2 as embassy::util::Steal>::steal(),
-        interrupt::take!(TIM2),
-        clocks.apb1_clk(),
-    )
+    set_freqs(ClockFreqs {
+        tim2: clocks.apb1_clk(),
+    });
 }

embassy-stm32/src/rcc/mod.rs

@@ -6,7 +6,6 @@ cfg_if::cfg_if! {
         mod l0;
         pub use l0::*;
     } else {
-        pub type SystemClock = ();
         #[derive(Default)]
         pub struct Config {}
         pub unsafe fn init(_config: Config) -> SystemClock {