6 files changed, 551 insertions, 17 deletions

diff --git a/embassy-macros/src/chip/stm32.rs b/embassy-macros/src/chip/stm32.rs
index a1ceadd55..274560a03 100644
--- a/embassy-macros/src/chip/stm32.rs
+++ b/embassy-macros/src/chip/stm32.rs
@@ -7,20 +7,21 @@ pub fn generate(embassy_prefix: &ModulePrefix, config: syn::Expr) -> TokenStream
     let embassy_stm32_path = embassy_prefix.append("embassy_stm32").path();
 
     quote!(
-        use #embassy_stm32_path::{clock::Clock};
+        use #embassy_stm32_path::{interrupt, peripherals, clock::Clock, time::Hertz};
 
         let p = #embassy_stm32_path::init(#config);
 
-        /*
-        let mut rtc = #embass::RTC::new(unsafe { <peripherals::TIM2 as #embassy_path::util::Steal>::steal() }, interrupt::take!(TIM2));
-        let rtc = unsafe { make_static(&mut rtc) };
-        rtc.start();
-        let mut alarm = rtc.alarm0();
+        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_tim2();
 
-        unsafe { #embassy_path::time::set_clock(rtc) };
+        let mut alarm = clock.alarm1();
+        unsafe { #embassy_path::time::set_clock(clock) };
 
         let alarm = unsafe { make_static(&mut alarm) };
         executor.set_alarm(alarm);
-        */
     )
 }
diff --git a/embassy-stm32/src/clock.rs b/embassy-stm32/src/clock.rs
index 709a2d36c..3ae83bbb0 100644
--- a/embassy-stm32/src/clock.rs
+++ b/embassy-stm32/src/clock.rs
@@ -10,6 +10,7 @@ use embassy::time::{Clock as EmbassyClock, TICKS_PER_SECOND};
 
 use crate::interrupt::{CriticalSection, Interrupt, Mutex};
 use crate::pac::timer::TimGp16;
+use crate::rcc::get_freqs;
 use crate::time::Hertz;
 
 // Clock timekeeping works with something we call "periods", which are time intervals
@@ -75,6 +76,24 @@ impl<T: Instance> Clock<T> {
         }
     }
 
+    // TODO: Temporary until clock code generation is in place
+    pub fn start_tim2(&'static self) {
+        cfg_if::cfg_if! {
+            if #[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 { crate::rcc::get_freqs().apb1_clk };
+                self.start(timer_freq);
+            }
+        }
+    }
+
     pub fn start(&'static self, timer_freq: Hertz) {
         let inner = T::inner();
 
diff --git a/embassy-stm32/src/lib.rs b/embassy-stm32/src/lib.rs
index 365b58f3c..01e6ea51b 100644
--- a/embassy-stm32/src/lib.rs
+++ b/embassy-stm32/src/lib.rs
@@ -47,6 +47,13 @@ pub struct Config {
     rcc: rcc::Config,
 }
 
+impl Config {
+    pub fn rcc(mut self, rcc: rcc::Config) -> Self {
+        self.rcc = rcc;
+        self
+    }
+}
+
 impl Default for Config {
     fn default() -> Self {
         Self {
diff --git a/embassy-stm32/src/rcc/h7/mod.rs b/embassy-stm32/src/rcc/h7/mod.rs
index 85e1cd00f..26d9f0bb9 100644
--- a/embassy-stm32/src/rcc/h7/mod.rs
+++ b/embassy-stm32/src/rcc/h7/mod.rs
@@ -528,6 +528,5 @@ impl<'d> Rcc<'d> {
     }
 }
 
-pub unsafe fn init(config: Config) {
-    // TODO
-}
+// TODO
+pub unsafe fn init(_config: Config) {}
diff --git a/embassy-stm32/src/rcc/l0/mod.rs b/embassy-stm32/src/rcc/l0/mod.rs
index 000aaa9e0..0cf3c2cb7 100644
--- a/embassy-stm32/src/rcc/l0/mod.rs
+++ b/embassy-stm32/src/rcc/l0/mod.rs
@@ -1,13 +1,484 @@
 use crate::pac;
-use embassy::util::Steal;
-use pac::rcc::{self, vals};
+use crate::pac::peripherals::{self, RCC};
+use crate::rcc::{set_freqs, Clocks};
+use crate::time::Hertz;
+use crate::time::U32Ext;
+use embassy::util::Unborrow;
+use pac::rcc::vals;
+use vals::{Hpre, Msirange, Plldiv, Pllmul, Pllon, Pllsrc, Ppre, Sw};
 
-#[derive(Default)]
-pub struct Config {}
+/// Most of clock setup is copied from stm32l0xx-hal, and adopted to the generated PAC,
+/// and with the addition of the init function to configure a system clock.
+
+/// System clock mux source
+#[derive(Clone, Copy)]
+pub enum ClockSrc {
+    MSI(MSIRange),
+    PLL(PLLSource, PLLMul, PLLDiv),
+    HSE(Hertz),
+    HSI16,
+}
+
+/// MSI Clock Range
+///
+/// These ranges control the frequency of the MSI. Internally, these ranges map
+/// to the `MSIRANGE` bits in the `RCC_ICSCR` register.
+#[derive(Clone, Copy)]
+pub enum MSIRange {
+    /// Around 65.536 kHz
+    Range0,
+    /// Around 131.072 kHz
+    Range1,
+    /// Around 262.144 kHz
+    Range2,
+    /// Around 524.288 kHz
+    Range3,
+    /// Around 1.048 MHz
+    Range4,
+    /// Around 2.097 MHz (reset value)
+    Range5,
+    /// Around 4.194 MHz
+    Range6,
+}
+
+impl Default for MSIRange {
+    fn default() -> MSIRange {
+        MSIRange::Range5
+    }
+}
+
+/// PLL divider
+#[derive(Clone, Copy)]
+pub enum PLLDiv {
+    Div2,
+    Div3,
+    Div4,
+}
+
+/// PLL multiplier
+#[derive(Clone, Copy)]
+pub enum PLLMul {
+    Mul3,
+    Mul4,
+    Mul6,
+    Mul8,
+    Mul12,
+    Mul16,
+    Mul24,
+    Mul32,
+    Mul48,
+}
+
+/// AHB prescaler
+#[derive(Clone, Copy)]
+pub enum AHBPrescaler {
+    NotDivided,
+    Div2,
+    Div4,
+    Div8,
+    Div16,
+    Div64,
+    Div128,
+    Div256,
+    Div512,
+}
+
+/// APB prescaler
+#[derive(Clone, Copy)]
+pub enum APBPrescaler {
+    NotDivided,
+    Div2,
+    Div4,
+    Div8,
+    Div16,
+}
+
+/// PLL clock input source
+#[derive(Clone, Copy)]
+pub enum PLLSource {
+    HSI16,
+    HSE(Hertz),
+}
+
+/// HSI speed
+pub const HSI_FREQ: u32 = 16_000_000;
+
+impl Into<Pllmul> for PLLMul {
+    fn into(self) -> Pllmul {
+        match self {
+            PLLMul::Mul3 => Pllmul::MUL3,
+            PLLMul::Mul4 => Pllmul::MUL4,
+            PLLMul::Mul6 => Pllmul::MUL6,
+            PLLMul::Mul8 => Pllmul::MUL8,
+            PLLMul::Mul12 => Pllmul::MUL12,
+            PLLMul::Mul16 => Pllmul::MUL16,
+            PLLMul::Mul24 => Pllmul::MUL24,
+            PLLMul::Mul32 => Pllmul::MUL32,
+            PLLMul::Mul48 => Pllmul::MUL48,
+        }
+    }
+}
+
+impl Into<Plldiv> for PLLDiv {
+    fn into(self) -> Plldiv {
+        match self {
+            PLLDiv::Div2 => Plldiv::DIV2,
+            PLLDiv::Div3 => Plldiv::DIV3,
+            PLLDiv::Div4 => Plldiv::DIV4,
+        }
+    }
+}
+
+impl Into<Pllsrc> for PLLSource {
+    fn into(self) -> Pllsrc {
+        match self {
+            PLLSource::HSI16 => Pllsrc::HSI16,
+            PLLSource::HSE(_) => Pllsrc::HSE,
+        }
+    }
+}
+
+impl Into<Ppre> for APBPrescaler {
+    fn into(self) -> Ppre {
+        match self {
+            APBPrescaler::NotDivided => Ppre::DIV1,
+            APBPrescaler::Div2 => Ppre::DIV2,
+            APBPrescaler::Div4 => Ppre::DIV4,
+            APBPrescaler::Div8 => Ppre::DIV8,
+            APBPrescaler::Div16 => Ppre::DIV16,
+        }
+    }
+}
+
+impl Into<Hpre> for AHBPrescaler {
+    fn into(self) -> Hpre {
+        match self {
+            AHBPrescaler::NotDivided => Hpre::DIV1,
+            AHBPrescaler::Div2 => Hpre::DIV2,
+            AHBPrescaler::Div4 => Hpre::DIV4,
+            AHBPrescaler::Div8 => Hpre::DIV8,
+            AHBPrescaler::Div16 => Hpre::DIV16,
+            AHBPrescaler::Div64 => Hpre::DIV64,
+            AHBPrescaler::Div128 => Hpre::DIV128,
+            AHBPrescaler::Div256 => Hpre::DIV256,
+            AHBPrescaler::Div512 => Hpre::DIV512,
+        }
+    }
+}
+
+impl Into<Msirange> for MSIRange {
+    fn into(self) -> Msirange {
+        match self {
+            MSIRange::Range0 => Msirange::RANGE0,
+            MSIRange::Range1 => Msirange::RANGE1,
+            MSIRange::Range2 => Msirange::RANGE2,
+            MSIRange::Range3 => Msirange::RANGE3,
+            MSIRange::Range4 => Msirange::RANGE4,
+            MSIRange::Range5 => Msirange::RANGE5,
+            MSIRange::Range6 => Msirange::RANGE6,
+        }
+    }
+}
+
+/// Clocks configutation
+pub struct Config {
+    mux: ClockSrc,
+    ahb_pre: AHBPrescaler,
+    apb1_pre: APBPrescaler,
+    apb2_pre: APBPrescaler,
+}
+
+impl Default for Config {
+    #[inline]
+    fn default() -> Config {
+        Config {
+            mux: ClockSrc::MSI(MSIRange::default()),
+            ahb_pre: AHBPrescaler::NotDivided,
+            apb1_pre: APBPrescaler::NotDivided,
+            apb2_pre: APBPrescaler::NotDivided,
+        }
+    }
+}
+
+impl Config {
+    #[inline]
+    pub fn clock_src(mut self, mux: ClockSrc) -> Self {
+        self.mux = mux;
+        self
+    }
+
+    #[inline]
+    pub fn ahb_pre(mut self, pre: AHBPrescaler) -> Self {
+        self.ahb_pre = pre;
+        self
+    }
+
+    #[inline]
+    pub fn apb1_pre(mut self, pre: APBPrescaler) -> Self {
+        self.apb1_pre = pre;
+        self
+    }
+
+    #[inline]
+    pub fn apb2_pre(mut self, pre: APBPrescaler) -> Self {
+        self.apb2_pre = pre;
+        self
+    }
+}
+
+/// RCC peripheral
+pub struct Rcc {}
+
+impl Rcc {
+    pub fn new(_rcc: impl Unborrow<Target = peripherals::RCC> + 'static) -> Self {
+        Self {}
+    }
+}
+
+/*
+    pub fn enable_lse(&mut self, _: &PWR) -> LSE {
+        self.rb.csr.modify(|_, w| {
+            // Enable LSE clock
+            w.lseon().set_bit()
+        });
+        while self.rb.csr.read().lserdy().bit_is_clear() {}
+        LSE(())
+    }
+}
+impl Rcc {
+    pub fn enable_hsi48(&mut self, syscfg: &mut SYSCFG, crs: CRS) -> HSI48 {
+        // Reset CRS peripheral
+        self.rb.apb1rstr.modify(|_, w| w.crsrst().set_bit());
+        self.rb.apb1rstr.modify(|_, w| w.crsrst().clear_bit());
+
+        // Enable CRS peripheral
+        self.rb.apb1enr.modify(|_, w| w.crsen().set_bit());
+
+        // Initialize CRS
+        crs.cfgr.write(|w|
+            // Select LSE as synchronization source
+            unsafe { w.syncsrc().bits(0b01) });
+        crs.cr
+            .modify(|_, w| w.autotrimen().set_bit().cen().set_bit());
+
+        // Enable VREFINT reference for HSI48 oscillator
+        syscfg
+            .syscfg
+            .cfgr3
+            .modify(|_, w| w.enref_hsi48().set_bit().en_vrefint().set_bit());
+
+        // Select HSI48 as USB clock
+        self.rb.ccipr.modify(|_, w| w.hsi48msel().set_bit());
+
+        // Enable dedicated USB clock
+        self.rb.crrcr.modify(|_, w| w.hsi48on().set_bit());
+        while self.rb.crrcr.read().hsi48rdy().bit_is_clear() {}
+
+        HSI48(())
+    }
+}
+
+impl Rcc {
+    /// Configure MCO (Microcontroller Clock Output).
+    pub fn configure_mco<P>(
+        &mut self,
+        source: MCOSEL_A,
+        prescaler: MCOPRE_A,
+        output_pin: P,
+    ) -> MCOEnabled
+    where
+        P: mco::Pin,
+    {
+        output_pin.into_mco();
+
+        self.rb.cfgr.modify(|_, w| {
+            w.mcosel().variant(source);
+            w.mcopre().variant(prescaler)
+        });
+
+        MCOEnabled(())
+    }
+}
+*/
+
+/// Extension trait that freezes the `RCC` peripheral with provided clocks configuration
+pub trait RccExt {
+    fn freeze(self, config: Config) -> Clocks;
+}
+
+impl RccExt for RCC {
+    // `cfgr` is almost always a constant, so make sure it can be constant-propagated properly by
+    // marking this function and all `Config` constructors and setters as `#[inline]`.
+    // This saves ~900 Bytes for the `pwr.rs` example.
+    #[inline]
+    fn freeze(self, cfgr: Config) -> Clocks {
+        let rcc = pac::RCC;
+        let (sys_clk, sw) = match cfgr.mux {
+            ClockSrc::MSI(range) => {
+                // Set MSI range
+                unsafe {
+                    rcc.icscr().write(|w| w.set_msirange(range.into()));
+                }
+
+                // Enable MSI
+                unsafe {
+                    rcc.cr().write(|w| w.set_msion(Pllon::ENABLED));
+                    while !rcc.cr().read().msirdy() {}
+                }
+
+                let freq = 32_768 * (1 << (range as u8 + 1));
+                (freq, Sw::MSI)
+            }
+            ClockSrc::HSI16 => {
+                // Enable HSI16
+                unsafe {
+                    rcc.cr().write(|w| w.set_hsi16on(Pllon::ENABLED));
+                    while !rcc.cr().read().hsi16rdyf() {}
+                }
+
+                (HSI_FREQ, Sw::HSI16)
+            }
+            ClockSrc::HSE(freq) => {
+                // Enable HSE
+                unsafe {
+                    rcc.cr().write(|w| w.set_hseon(Pllon::ENABLED));
+                    while !rcc.cr().read().hserdy() {}
+                }
+
+                (freq.0, Sw::HSE)
+            }
+            ClockSrc::PLL(src, mul, div) => {
+                let freq = match src {
+                    PLLSource::HSE(freq) => {
+                        // Enable HSE
+                        unsafe {
+                            rcc.cr().write(|w| w.set_hseon(Pllon::ENABLED));
+                            while !rcc.cr().read().hserdy() {}
+                        }
+                        freq.0
+                    }
+                    PLLSource::HSI16 => {
+                        // Enable HSI
+                        unsafe {
+                            rcc.cr().write(|w| w.set_hsi16on(Pllon::ENABLED));
+                            while !rcc.cr().read().hsi16rdyf() {}
+                        }
+                        HSI_FREQ
+                    }
+                };
+
+                // Disable PLL
+                unsafe {
+                    rcc.cr().modify(|w| w.set_pllon(Pllon::DISABLED));
+                    while rcc.cr().read().pllrdy() {}
+                }
+
+                let freq = match mul {
+                    PLLMul::Mul3 => freq * 3,
+                    PLLMul::Mul4 => freq * 4,
+                    PLLMul::Mul6 => freq * 6,
+                    PLLMul::Mul8 => freq * 8,
+                    PLLMul::Mul12 => freq * 12,
+                    PLLMul::Mul16 => freq * 16,
+                    PLLMul::Mul24 => freq * 24,
+                    PLLMul::Mul32 => freq * 32,
+                    PLLMul::Mul48 => freq * 48,
+                };
+
+                let freq = match div {
+                    PLLDiv::Div2 => freq / 2,
+                    PLLDiv::Div3 => freq / 3,
+                    PLLDiv::Div4 => freq / 4,
+                };
+                assert!(freq <= 32_u32.mhz().0);
+
+                unsafe {
+                    rcc.cfgr().write(move |w| {
+                        w.set_pllmul(mul.into());
+                        w.set_plldiv(div.into());
+                        w.set_pllsrc(src.into());
+                    });
+
+                    // Enable PLL
+                    rcc.cr().modify(|w| w.set_pllon(Pllon::ENABLED));
+                    while !rcc.cr().read().pllrdy() {}
+                }
+
+                (freq, Sw::PLL)
+            }
+        };
+
+        unsafe {
+            rcc.cfgr().modify(|w| {
+                w.set_sw(sw.into());
+                w.set_hpre(cfgr.ahb_pre.into());
+                w.set_ppre(0, cfgr.apb1_pre.into());
+                w.set_ppre(1, cfgr.apb2_pre.into());
+            });
+        }
+
+        let ahb_freq: u32 = match cfgr.ahb_pre {
+            AHBPrescaler::NotDivided => sys_clk,
+            pre => {
+                let pre: Hpre = pre.into();
+                let pre = 1 << (pre.0 as u32 - 7);
+                sys_clk / pre
+            }
+        };
+
+        let (apb1_freq, apb1_tim_freq, apb1_pre) = match cfgr.apb1_pre {
+            APBPrescaler::NotDivided => (ahb_freq, ahb_freq, 1),
+            pre => {
+                let pre: Ppre = pre.into();
+                let pre: u8 = 1 << (pre.0 - 3);
+                let freq = ahb_freq / pre as u32;
+                (freq, freq * 2, pre as u8)
+            }
+        };
+
+        let (apb2_freq, apb2_tim_freq, apb2_pre) = match cfgr.apb2_pre {
+            APBPrescaler::NotDivided => (ahb_freq, ahb_freq, 1),
+            pre => {
+                let pre: Ppre = pre.into();
+                let pre: u8 = 1 << (pre.0 - 3);
+                let freq = ahb_freq / (1 << (pre as u8 - 3));
+                (freq, freq * 2, pre as u8)
+            }
+        };
+
+        Clocks {
+            sys_clk: sys_clk.hz(),
+            ahb_clk: ahb_freq.hz(),
+            apb1_clk: apb1_freq.hz(),
+            apb2_clk: apb2_freq.hz(),
+            apb1_tim_clk: apb1_tim_freq.hz(),
+            apb2_tim_clk: apb2_tim_freq.hz(),
+            apb1_pre,
+            apb2_pre,
+        }
+    }
+}
+
+/// Token that exists only, if the HSI48 clock has been enabled
+///
+/// You can get an instance of this struct by calling [`Rcc::enable_hsi48`].
+#[derive(Clone, Copy)]
+pub struct HSI48(());
+
+/// Token that exists only if MCO (Microcontroller Clock Out) has been enabled.
+///
+/// You can get an instance of this struct by calling [`Rcc::configure_mco`].
+#[derive(Clone, Copy)]
+pub struct MCOEnabled(());
+
+/// Token that exists only, if the LSE clock has been enabled
+///
+/// You can get an instance of this struct by calling [`Rcc::enable_lse`].
+#[derive(Clone, Copy)]
+pub struct LSE(());
 
 pub unsafe fn init(config: Config) {
     let rcc = pac::RCC;
-
     let enabled = vals::Iophen::ENABLED;
     rcc.iopenr().write(|w| {
         w.set_iopaen(enabled);
@@ -17,4 +488,8 @@ pub unsafe fn init(config: Config) {
         w.set_iopeen(enabled);
         w.set_iophen(enabled);
     });
+
+    let r = <peripherals::RCC as embassy::util::Steal>::steal();
+    let clocks = r.freeze(config);
+    set_freqs(clocks);
 }
diff --git a/embassy-stm32/src/rcc/mod.rs b/embassy-stm32/src/rcc/mod.rs
index 59938e7bf..cb8780343 100644
--- a/embassy-stm32/src/rcc/mod.rs
+++ b/embassy-stm32/src/rcc/mod.rs
@@ -1,3 +1,35 @@
+use crate::time::Hertz;
+use core::mem::MaybeUninit;
+
+/// Frozen clock frequencies
+///
+/// The existence of this value indicates that the clock configuration can no longer be changed
+#[derive(Clone, Copy)]
+pub struct Clocks {
+    pub sys_clk: Hertz,
+    pub ahb_clk: Hertz,
+    pub apb1_clk: Hertz,
+    pub apb1_tim_clk: Hertz,
+    pub apb2_clk: Hertz,
+    pub apb2_tim_clk: Hertz,
+    pub apb1_pre: u8,
+    pub apb2_pre: u8,
+}
+
+static mut CLOCK_FREQS: MaybeUninit<Clocks> = MaybeUninit::uninit();
+
+/// Sets the clock frequencies
+///
+/// Safety: Sets a mutable global.
+pub unsafe fn set_freqs(freqs: Clocks) {
+    CLOCK_FREQS.as_mut_ptr().write(freqs);
+}
+
+/// Safety: Reads a mutable global.
+pub unsafe fn get_freqs() -> &'static Clocks {
+    &*CLOCK_FREQS.as_ptr()
+}
+
 cfg_if::cfg_if! {
     if #[cfg(feature = "_stm32h7")] {
         mod h7;
@@ -8,6 +40,7 @@ cfg_if::cfg_if! {
     } else {
         #[derive(Default)]
         pub struct Config {}
-        pub fn init(_config: Config) {}
+        pub unsafe fn init(_config: Config) {
+        }
     }
 }