Add F0 RCC

3 files changed, 238 insertions, 1 deletions

diff --git a/embassy-stm32/src/rcc/f0/mod.rs b/embassy-stm32/src/rcc/f0/mod.rs
new file mode 100644
index 000000000..8ddacb8ef
--- /dev/null
+++ b/embassy-stm32/src/rcc/f0/mod.rs
@@ -0,0 +1,231 @@
+use core::marker::PhantomData;
+
+use embassy::util::Unborrow;
+
+use crate::pac::{DBGMCU, FLASH, RCC};
+use crate::peripherals;
+use crate::time::Hertz;
+
+use super::{set_freqs, Clocks};
+
+const HSI: u32 = 8_000_000;
+
+/// Configuration of the clocks
+///
+/// hse takes precedence over hsi48 if both are enabled
+#[non_exhaustive]
+#[derive(Default)]
+pub struct Config {
+    pub hse: Option<Hertz>,
+    pub bypass_hse: bool,
+    pub usb_pll: bool,
+
+    #[cfg(rcc_f0)]
+    pub hsi48: bool,
+
+    pub sys_ck: Option<Hertz>,
+    pub hclk: Option<Hertz>,
+    pub pclk: Option<Hertz>,
+    pub enable_debug_wfe: bool,
+}
+
+pub struct Rcc<'d> {
+    inner: PhantomData<&'d ()>,
+    config: Config,
+}
+
+impl<'d> Rcc<'d> {
+    pub fn new(_rcc: impl Unborrow<Target = peripherals::RCC> + 'd, config: Config) -> Self {
+        Self {
+            inner: PhantomData,
+            config,
+        }
+    }
+
+    pub fn freeze(self) -> Clocks {
+        use crate::pac::rcc::vals::{Hpre, Hsebyp, Pllmul, Pllsrc, Ppre, Sw, Usbsw};
+
+        let sysclk = self.config.sys_ck.map(|v| v.0).unwrap_or(HSI);
+
+        let (src_clk, use_hsi48) = self.config.hse.map(|v| (v.0, false)).unwrap_or_else(|| {
+            #[cfg(rcc_f0)]
+            if self.config.hsi48 {
+                return (48_000_000, true);
+            }
+            (HSI, false)
+        });
+
+        let (pllmul_bits, real_sysclk) = if sysclk == src_clk {
+            (None, sysclk)
+        } else {
+            let prediv = if self.config.hse.is_some() { 1 } else { 2 };
+            let pllmul = (2 * prediv * sysclk + src_clk) / src_clk / 2;
+            let pllmul = pllmul.max(2).min(16);
+
+            let pllmul_bits = pllmul as u8 - 2;
+            let real_sysclk = pllmul * src_clk / prediv;
+            (Some(pllmul_bits), real_sysclk)
+        };
+
+        let hpre_bits = self
+            .config
+            .hclk
+            .map(|hclk| match real_sysclk / hclk.0 {
+                0 => unreachable!(),
+                1 => 0b0111,
+                2 => 0b1000,
+                3..=5 => 0b1001,
+                6..=11 => 0b1010,
+                12..=39 => 0b1011,
+                40..=95 => 0b1100,
+                96..=191 => 0b1101,
+                192..=383 => 0b1110,
+                _ => 0b1111,
+            })
+            .unwrap_or(0b0111);
+        let hclk = real_sysclk / (1 << (hpre_bits - 0b0111));
+
+        let ppre_bits = self
+            .config
+            .pclk
+            .map(|pclk| match hclk / pclk.0 {
+                0 => unreachable!(),
+                1 => 0b011,
+                2 => 0b100,
+                3..=5 => 0b101,
+                6..=11 => 0b110,
+                _ => 0b111,
+            })
+            .unwrap_or(0b011);
+
+        let ppre: u8 = 1 << (ppre_bits - 0b011);
+        let pclk = hclk / u32::from(ppre);
+
+        let timer_mul = if ppre == 1 { 1 } else { 2 };
+
+        // NOTE(safety) Atomic write
+        unsafe {
+            FLASH.acr().write(|w| {
+                let latency = if real_sysclk <= 24_000_000 {
+                    0
+                } else if real_sysclk <= 48_000_000 {
+                    1
+                } else {
+                    2
+                };
+                w.latency().0 = latency;
+            });
+        }
+
+        // NOTE(unsafe) We have exclusive access to the RCC
+        unsafe {
+            match (self.config.hse.is_some(), use_hsi48) {
+                (true, _) => {
+                    RCC.cr().modify(|w| {
+                        w.set_csson(true);
+                        w.set_hseon(true);
+
+                        if self.config.bypass_hse {
+                            w.set_hsebyp(Hsebyp::BYPASSED);
+                        }
+                    });
+                    while !RCC.cr().read().hserdy() {}
+
+                    if pllmul_bits.is_some() {
+                        RCC.cfgr().modify(|w| w.set_pllsrc(Pllsrc::HSE_DIV_PREDIV))
+                    }
+                }
+                (false, true) => {
+                    // use_hsi48 will always be false for rcc_f0x0
+                    #[cfg(rcc_f0)]
+                    RCC.cr2().modify(|w| w.set_hsi48on(true));
+                    #[cfg(rcc_f0)]
+                    while !RCC.cr2().read().hsi48rdy() {}
+
+                    #[cfg(rcc_f0)]
+                    if pllmul_bits.is_some() {
+                        RCC.cfgr()
+                            .modify(|w| w.set_pllsrc(Pllsrc::HSI48_DIV_PREDIV))
+                    }
+                }
+                _ => {
+                    RCC.cr().modify(|w| w.set_hsion(true));
+                    while !RCC.cr().read().hsirdy() {}
+
+                    if pllmul_bits.is_some() {
+                        RCC.cfgr().modify(|w| w.set_pllsrc(Pllsrc::HSI_DIV2))
+                    }
+                }
+            }
+
+            if self.config.usb_pll {
+                RCC.cfgr3().modify(|w| w.set_usbsw(Usbsw::PLLCLK));
+            }
+            // TODO: Option to use CRS (Clock Recovery)
+
+            if let Some(pllmul_bits) = pllmul_bits {
+                RCC.cfgr().modify(|w| w.set_pllmul(Pllmul(pllmul_bits)));
+
+                RCC.cr().modify(|w| w.set_pllon(true));
+                while !RCC.cr().read().pllrdy() {}
+
+                RCC.cfgr().modify(|w| {
+                    w.set_ppre(Ppre(ppre_bits));
+                    w.set_hpre(Hpre(hpre_bits));
+                    w.set_sw(Sw::PLL)
+                });
+            } else {
+                RCC.cfgr().modify(|w| {
+                    w.set_ppre(Ppre(ppre_bits));
+                    w.set_hpre(Hpre(hpre_bits));
+
+                    if self.config.hse.is_some() {
+                        w.set_sw(Sw::HSE);
+                    } else if use_hsi48 {
+                        #[cfg(rcc_f0)]
+                        w.set_sw(Sw::HSI48);
+                    } else {
+                        w.set_sw(Sw::HSI)
+                    }
+                })
+            }
+
+            if self.config.enable_debug_wfe {
+                RCC.ahbenr().modify(|w| w.set_dmaen(true));
+
+                critical_section::with(|_| {
+                    DBGMCU.cr().modify(|w| {
+                        w.set_dbg_standby(true);
+                        w.set_dbg_stop(true);
+                    });
+                });
+            }
+        }
+
+        Clocks {
+            sys: Hertz(real_sysclk),
+            apb1: Hertz(pclk),
+            apb1_tim: Hertz(pclk * timer_mul),
+            apb2_tim: Hertz(0),
+            ahb: Hertz(hclk),
+        }
+    }
+}
+
+pub unsafe fn init(config: Config) {
+    RCC.ahbenr().modify(|w| {
+        w.set_iopaen(true);
+        w.set_iopben(true);
+        w.set_iopcen(true);
+        w.set_iopden(true);
+
+        #[cfg(rcc_f0)]
+        w.set_iopeen(true);
+
+        w.set_iopfen(true);
+    });
+
+    let rcc = Rcc::new(<peripherals::RCC as embassy::util::Steal>::steal(), config);
+    let clocks = rcc.freeze();
+    set_freqs(clocks);
+}
diff --git a/embassy-stm32/src/rcc/mod.rs b/embassy-stm32/src/rcc/mod.rs
index e84021272..91e8b5bef 100644
--- a/embassy-stm32/src/rcc/mod.rs
+++ b/embassy-stm32/src/rcc/mod.rs
@@ -9,11 +9,14 @@ mod types;
 pub struct Clocks {
     pub sys: Hertz,
     pub apb1: Hertz,
+
+    #[cfg(not(any(rcc_f0, rcc_f0x0)))]
     pub apb2: Hertz,
+
     pub apb1_tim: Hertz,
     pub apb2_tim: Hertz,
 
-    #[cfg(any(rcc_l0))]
+    #[cfg(any(rcc_l0, rcc_f0, rcc_f0x0))]
     pub ahb: Hertz,
 
     #[cfg(any(rcc_l4, rcc_f4, rcc_h7, rcc_wb55, rcc_wl5x))]
@@ -65,6 +68,9 @@ cfg_if::cfg_if! {
     } else if #[cfg(rcc_wl5x)] {
         mod wl5x;
         pub use wl5x::*;
+    } else if #[cfg(any(rcc_f0, rcc_f0x0))] {
+        mod f0;
+        pub use f0::*;
     }
 }
 
diff --git a/stm32-data b/stm32-data
-Subproject 18f86c83123771048f971350c99c4f810385d7d
+Subproject eb76ee900ac67b51497196572250323e82666b4