More work on H7 RCC

3 files changed, 205 insertions, 20 deletions

diff --git a/embassy-stm32/src/rcc/h7/mod.rs b/embassy-stm32/src/rcc/h7/mod.rs
index 69b9c79a9..b27eff747 100644
--- a/embassy-stm32/src/rcc/h7/mod.rs
+++ b/embassy-stm32/src/rcc/h7/mod.rs
@@ -1,27 +1,212 @@
+use core::marker::PhantomData;
+
+use embassy::util::Unborrow;
+use embassy_extras::unborrow;
+
+use crate::fmt::assert;
+use crate::pac::peripherals;
 use crate::pac::RCC;
+use crate::time::Hertz;
 
 mod pll;
+use pll::pll_setup;
 pub use pll::PllConfig;
 
-const HSI: u32 = 64_000_000; // Hz
-const CSI: u32 = 4_000_000; // Hz
-const HSI48: u32 = 48_000_000; // Hz
-const LSI: u32 = 32_000; // Hz
+const HSI: Hertz = Hertz(64_000_000);
+const CSI: Hertz = Hertz(4_000_000);
+const HSI48: Hertz = Hertz(48_000_000);
+const LSI: Hertz = Hertz(32_000);
 
 /// Configuration of the core clocks
 #[non_exhaustive]
 #[derive(Default)]
 pub struct Config {
-    pub hse: Option<u32>,
+    pub hse: Option<Hertz>,
     pub bypass_hse: bool,
-    pub sys_ck: Option<u32>,
-    pub per_ck: Option<u32>,
-    pub hclk: Option<u32>,
-    pub pclk1: Option<u32>,
-    pub pclk2: Option<u32>,
-    pub pclk3: Option<u32>,
-    pub pclk4: Option<u32>,
+    pub sys_ck: Option<Hertz>,
+    pub per_ck: Option<Hertz>,
+    rcc_hclk: Option<Hertz>,
+    pub hclk: Option<Hertz>,
+    pub pclk1: Option<Hertz>,
+    pub pclk2: Option<Hertz>,
+    pub pclk3: Option<Hertz>,
+    pub pclk4: Option<Hertz>,
     pub pll1: PllConfig,
     pub pll2: PllConfig,
     pub pll3: PllConfig,
+    pub vos: VoltageScale,
+}
+
+/// Voltage Scale
+///
+/// Represents the voltage range feeding the CPU core. The maximum core
+/// clock frequency depends on this value.
+#[derive(Copy, Clone, PartialEq)]
+pub enum VoltageScale {
+    /// VOS 0 range VCORE 1.26V - 1.40V
+    Scale0,
+    /// VOS 1 range VCORE 1.15V - 1.26V
+    Scale1,
+    /// VOS 2 range VCORE 1.05V - 1.15V
+    Scale2,
+    /// VOS 3 range VCORE 0.95V - 1.05V
+    Scale3,
+}
+
+impl Default for VoltageScale {
+    fn default() -> Self {
+        Self::Scale1
+    }
+}
+
+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,
+        }
+    }
+
+    // TODO: FLASH and PWR
+    /// Freeze the core clocks, returning a Core Clocks Distribution
+    /// and Reset (CCDR) structure. The actual frequency of the clocks
+    /// configured is returned in the `clocks` member of the CCDR
+    /// structure.
+    ///
+    /// Note that `freeze` will never result in a clock _faster_ than
+    /// that specified. It may result in a clock that is a factor of [1,
+    /// 2) slower.
+    ///
+    /// `syscfg` is required to enable the I/O compensation cell.
+    ///
+    /// # Panics
+    ///
+    /// If a clock specification cannot be achieved within the
+    /// hardware specification then this function will panic. This
+    /// function may also panic if a clock specification can be
+    /// achieved, but the mechanism for doing so is not yet
+    /// implemented here.
+    pub fn freeze(mut self) {
+        use crate::pac::rcc::vals::{Ckpersel, Hpre, Hsidiv, Hsion, Lsion, Timpre};
+
+        let srcclk = self.config.hse.unwrap_or(HSI); // Available clocks
+        let (sys_ck, sys_use_pll1_p) = self.sys_ck_setup(srcclk);
+
+        // NOTE(unsafe) We have exclusive access to the RCC
+        let (pll1_p_ck, pll1_q_ck, pll1_r_ck) =
+            unsafe { pll_setup(srcclk.0, &self.config.pll1, 0) };
+        let (pll2_p_ck, pll2_q_ck, pll2_r_ck) =
+            unsafe { pll_setup(srcclk.0, &self.config.pll2, 1) };
+        let (pll3_p_ck, pll3_q_ck, pll3_r_ck) =
+            unsafe { pll_setup(srcclk.0, &self.config.pll3, 2) };
+
+        let sys_ck = if sys_use_pll1_p {
+            Hertz(pll1_p_ck.unwrap()) // Must have been set by sys_ck_setup
+        } else {
+            sys_ck
+        };
+
+        // NOTE(unsafe) We own the regblock
+        unsafe {
+            // This routine does not support HSIDIV != 1. To
+            // do so it would need to ensure all PLLxON bits are clear
+            // before changing the value of HSIDIV
+            let cr = RCC.cr().read();
+            assert!(cr.hsion() == Hsion::ON);
+            assert!(cr.hsidiv() == Hsidiv::DIV1);
+
+            RCC.csr().modify(|w| w.set_lsion(Lsion::ON));
+            while !RCC.csr().read().lsirdy() {}
+        }
+
+        // per_ck from HSI by default
+        let (per_ck, ckpersel) = match (self.config.per_ck == self.config.hse, self.config.per_ck) {
+            (true, Some(hse)) => (hse, Ckpersel::HSE), // HSE
+            (_, Some(CSI)) => (CSI, Ckpersel::CSI),    // CSI
+            _ => (HSI, Ckpersel::HSI),                 // HSI
+        };
+
+        // D1 Core Prescaler
+        // Set to 1
+        let d1cpre_bits = 0;
+        let d1cpre_div = 1;
+        let sys_d1cpre_ck = sys_ck.0 / d1cpre_div;
+
+        // Timer prescaler selection
+        let timpre = Timpre::DEFAULTX2;
+
+        // Refer to part datasheet "General operating conditions"
+        // table for (rev V). We do not assert checks for earlier
+        // revisions which may have lower limits.
+        let (sys_d1cpre_ck_max, rcc_hclk_max, pclk_max) = match self.config.vos {
+            VoltageScale::Scale0 => (480_000_000, 240_000_000, 120_000_000),
+            VoltageScale::Scale1 => (400_000_000, 200_000_000, 100_000_000),
+            VoltageScale::Scale2 => (300_000_000, 150_000_000, 75_000_000),
+            _ => (200_000_000, 100_000_000, 50_000_000),
+        };
+        assert!(sys_d1cpre_ck <= sys_d1cpre_ck_max);
+
+        let rcc_hclk = self
+            .config
+            .rcc_hclk
+            .map(|v| v.0)
+            .unwrap_or(sys_d1cpre_ck / 2);
+        assert!(rcc_hclk <= rcc_hclk_max);
+
+        // Estimate divisor
+        let (hpre_bits, hpre_div) = match (sys_d1cpre_ck + rcc_hclk - 1) / rcc_hclk {
+            0 => unreachable!(),
+            1 => (Hpre::DIV1, 1),
+            2 => (Hpre::DIV2, 2),
+            3..=5 => (Hpre::DIV4, 4),
+            6..=11 => (Hpre::DIV8, 8),
+            12..=39 => (Hpre::DIV16, 16),
+            40..=95 => (Hpre::DIV64, 64),
+            96..=191 => (Hpre::DIV128, 128),
+            192..=383 => (Hpre::DIV256, 256),
+            _ => (Hpre::DIV512, 512),
+        };
+        // Calculate real AXI and AHB clock
+        let rcc_hclk = sys_d1cpre_ck / hpre_div;
+        assert!(rcc_hclk <= rcc_hclk_max);
+        let rcc_aclk = rcc_hclk; // AXI clock is always equal to AHB clock on H7
+
+        todo!()
+    }
+
+    /// Setup sys_ck
+    /// Returns sys_ck frequency, and a pll1_p_ck
+    fn sys_ck_setup(&mut self, srcclk: Hertz) -> (Hertz, bool) {
+        // Compare available with wanted clocks
+        let sys_ck = self.config.sys_ck.unwrap_or(srcclk);
+
+        if sys_ck != srcclk {
+            // The requested system clock is not the immediately available
+            // HSE/HSI clock. Perhaps there are other ways of obtaining
+            // the requested system clock (such as `HSIDIV`) but we will
+            // ignore those for now.
+            //
+            // Therefore we must use pll1_p_ck
+            let pll1_p_ck = match self.config.pll1.p_ck {
+                Some(p_ck) => {
+                    assert!(p_ck == sys_ck,
+                            "Error: Cannot set pll1_p_ck independently as it must be used to generate sys_ck");
+                    Some(p_ck)
+                }
+                None => Some(sys_ck),
+            };
+            self.config.pll1.p_ck = pll1_p_ck;
+
+            (sys_ck, true)
+        } else {
+            // sys_ck is derived directly from a source clock
+            // (HSE/HSI). pll1_p_ck can be as requested
+            (sys_ck, false)
+        }
+    }
 }
diff --git a/embassy-stm32/src/rcc/h7/pll.rs b/embassy-stm32/src/rcc/h7/pll.rs
index 37bd611cc..ead33e81e 100644
--- a/embassy-stm32/src/rcc/h7/pll.rs
+++ b/embassy-stm32/src/rcc/h7/pll.rs
@@ -1,4 +1,4 @@
-use super::{Config, HSI, RCC};
+use super::{Config, Hertz, HSI, RCC};
 use crate::fmt::assert;
 
 const VCO_MIN: u32 = 150_000_000;
@@ -6,9 +6,9 @@ const VCO_MAX: u32 = 420_000_000;
 
 #[derive(Default)]
 pub struct PllConfig {
-    pub p_ck: Option<u32>,
-    pub q_ck: Option<u32>,
-    pub r_ck: Option<u32>,
+    pub p_ck: Option<Hertz>,
+    pub q_ck: Option<Hertz>,
+    pub r_ck: Option<Hertz>,
 }
 
 pub(super) struct PllConfigResults {
@@ -84,7 +84,7 @@ pub(super) unsafe fn pll_setup(
 
     match config.p_ck {
         Some(requested_output) => {
-            let config_results = vco_setup(pll_src, requested_output, plln);
+            let config_results = vco_setup(pll_src, requested_output.0, plln);
             let PllConfigResults {
                 ref_x_ck,
                 pll_x_m,
@@ -113,7 +113,7 @@ pub(super) unsafe fn pll_setup(
 
             // Calulate additional output dividers
             let q_ck = match config.q_ck {
-                Some(ck) if ck > 0 => {
+                Some(Hertz(ck)) if ck > 0 => {
                     let div = (vco_ck + ck - 1) / ck;
                     RCC.plldivr(plln).modify(|w| w.set_divq1((div - 1) as u8));
                     RCC.pllcfgr()
@@ -123,7 +123,7 @@ pub(super) unsafe fn pll_setup(
                 _ => None,
             };
             let r_ck = match config.r_ck {
-                Some(ck) if ck > 0 => {
+                Some(Hertz(ck)) if ck > 0 => {
                     let div = (vco_ck + ck - 1) / ck;
                     RCC.plldivr(plln).modify(|w| w.set_divr1((div - 1) as u8));
                     RCC.pllcfgr()
diff --git a/embassy-stm32/src/time.rs b/embassy-stm32/src/time.rs
index c131415c4..ac03ce5c4 100644
--- a/embassy-stm32/src/time.rs
+++ b/embassy-stm32/src/time.rs
@@ -5,7 +5,7 @@
 pub struct Bps(pub u32);
 
 /// Hertz
-#[derive(PartialEq, PartialOrd, Clone, Copy, Debug)]
+#[derive(PartialEq, PartialOrd, Clone, Copy, Debug, Eq)]
 pub struct Hertz(pub u32);
 
 /// KiloHertz