//! Clock configuration.
//!
//! This module provides functionality to configure the RCC to generate the requested clocks.
//!
//! # Example
//!
//! ```
//! let dp = pac::Peripherals::take().unwrap();
//! let rcc = dp.RCC.constrain();
//! let clocks = rcc
//!     .cfgr
//!     .use_hse(8.MHz())
//!     .sysclk(168.MHz())
//!     .pclk1(24.MHz())
//!     .i2s_clk(86.MHz())
//!     .require_pll48clk()
//!     .freeze();
//!     // Test that the I2S clock is suitable for 48000kHz audio.
//!     assert!(clocks.i2s_clk().unwrap() == 48.MHz().into());
//! ```
//!
//! # Limitations
//!
//! Unlike the clock configuration tool provided by ST, the code does not extensively search all
//! possible configurations. Instead, it often relies on an iterative approach to reduce
//! computational complexity. On most MCUs the code will first generate a configuration for the 48
//! MHz clock and the system clock without taking other requested clocks into account, even if the
//! accuracy of these clocks is affected. **If you specific accuracy requirements, you should
//! always check the resulting frequencies!**
//!
//! Whereas the hardware often supports flexible clock source selection and many clocks can be
//! sourced from multiple PLLs, the code implements a fixed mapping between PLLs and clocks. The 48
//! MHz clock is always generated by the main PLL, the I2S clocks are always generated by the I2S
//! PLL (unless a matching external clock input is provided), and similarly the SAI clocks are
//! always generated by the SAI PLL. It is therefore not possible to, for example, specify two
//! different I2S frequencies unless you also provide a matching I2S_CKIN signal for one of them.
//!
//! Some MCUs have limited clock generation hardware and do not provide either I2S or SAI PLLs even
//! though I2S or SAI are available. On the STM32F410, the I2S clock is generated by the main PLL,
//! and on the STM32F413/423 SAI clocks are generated by the I2S PLL. On these MCUs, the actual
//! frequencies may substantially deviate from the requested frequencies.

use crate::pac::rcc::cfgr::{HPRE_A, SW_A};
use crate::pac::{self, rcc, RCC};

use fugit::HertzU32 as Hertz;
use fugit::RateExtU32;

#[cfg(not(feature = "gpio-f410"))]
use pll::I2sPll;
use pll::MainPll;
#[cfg(any(feature = "gpio-f427", feature = "gpio-f446", feature = "gpio-f469"))]
use pll::SaiPll;

mod pll;

mod enable;
use crate::pac::rcc::RegisterBlock as RccRB;

/// Bus associated to peripheral
pub trait RccBus: crate::Sealed {
    /// Bus type;
    type Bus;
}

/// Enable/disable peripheral
#[allow(clippy::missing_safety_doc)]
pub trait Enable: RccBus {
    /// Enables peripheral
    fn enable(rcc: &RccRB);

    /// Disables peripheral
    fn disable(rcc: &RccRB);

    /// Check if peripheral enabled
    fn is_enabled() -> bool;

    /// Check if peripheral disabled
    #[inline]
    fn is_disabled() -> bool {
        !Self::is_enabled()
    }

    /// # Safety
    ///
    /// Enables peripheral. Takes access to RCC internally
    unsafe fn enable_unchecked() {
        let rcc = &*pac::RCC::ptr();
        Self::enable(rcc);
    }

    /// # Safety
    ///
    /// Disables peripheral. Takes access to RCC internally
    unsafe fn disable_unchecked() {
        let rcc = pac::RCC::ptr();
        Self::disable(&*rcc);
    }
}

/// Low power enable/disable peripheral
#[allow(clippy::missing_safety_doc)]
pub trait LPEnable: RccBus {
    /// Enables peripheral in low power mode
    fn enable_in_low_power(rcc: &RccRB);

    /// Disables peripheral in low power mode
    fn disable_in_low_power(rcc: &RccRB);

    /// Check if peripheral enabled in low power mode
    fn is_enabled_in_low_power() -> bool;

    /// Check if peripheral disabled in low power mode
    #[inline]
    fn is_disabled_in_low_power() -> bool {
        !Self::is_enabled_in_low_power()
    }

    /// # Safety
    ///
    /// Enables peripheral in low power mode. Takes access to RCC internally
    unsafe fn enable_in_low_power_unchecked() {
        let rcc = pac::RCC::ptr();
        Self::enable_in_low_power(&*rcc);
    }

    /// # Safety
    ///
    /// Disables peripheral in low power mode. Takes access to RCC internally
    unsafe fn disable_in_low_power_unchecked() {
        let rcc = pac::RCC::ptr();
        Self::disable_in_low_power(&*rcc);
    }
}

/// Reset peripheral
#[allow(clippy::missing_safety_doc)]
pub trait Reset: RccBus {
    /// Resets peripheral
    fn reset(rcc: &RccRB);

    /// # Safety
    ///
    /// Resets peripheral. Takes access to RCC internally
    unsafe fn reset_unchecked() {
        let rcc = pac::RCC::ptr();
        Self::reset(&*rcc);
    }
}

/// Extension trait that constrains the `RCC` peripheral
pub trait RccExt {
    /// Constrains the `RCC` peripheral so it plays nicely with the other abstractions
    fn constrain(self) -> Rcc;
}

/// Frequency on bus that peripheral is connected in
pub trait BusClock {
    /// Calculates frequency depending on `Clock` state
    fn clock(clocks: &Clocks) -> Hertz;
}

/// Frequency on bus that timer is connected in
pub trait BusTimerClock {
    /// Calculates base frequency of timer depending on `Clock` state
    fn timer_clock(clocks: &Clocks) -> Hertz;
}

impl<T> BusClock for T
where
    T: RccBus,
    T::Bus: BusClock,
{
    fn clock(clocks: &Clocks) -> Hertz {
        T::Bus::clock(clocks)
    }
}

impl<T> BusTimerClock for T
where
    T: RccBus,
    T::Bus: BusTimerClock,
{
    fn timer_clock(clocks: &Clocks) -> Hertz {
        T::Bus::timer_clock(clocks)
    }
}

macro_rules! bus_struct {
    ($( $(#[$attr:meta])* $busX:ident => ($EN:ident, $en:ident, $LPEN:ident, $lpen:ident, $RST:ident, $rst:ident, $doc:literal),)+) => {
        $(
            $(#[$attr])*
            #[doc = $doc]
            pub struct $busX {
                _0: (),
            }

            $(#[$attr])*
            impl $busX {
                pub(crate) fn enr(rcc: &RccRB) -> &rcc::$EN {
                    &rcc.$en
                }

                pub(crate) fn lpenr(rcc: &RccRB) -> &rcc::$LPEN {
                    &rcc.$lpen
                }

                pub(crate) fn rstr(rcc: &RccRB) -> &rcc::$RST {
                    &rcc.$rst
                }
            }
        )+
    };
}

bus_struct! {
    APB1 => (APB1ENR, apb1enr, APB1LPENR, apb1lpenr, APB1RSTR, apb1rstr, "Advanced Peripheral Bus 1 (APB1) registers"),
    APB2 => (APB2ENR, apb2enr, APB2LPENR, apb2lpenr, APB2RSTR, apb2rstr, "Advanced Peripheral Bus 2 (APB2) registers"),
    AHB1 => (AHB1ENR, ahb1enr, AHB1LPENR, ahb1lpenr, AHB1RSTR, ahb1rstr, "Advanced High-performance Bus 1 (AHB1) registers"),
    #[cfg(not(feature = "gpio-f410"))]
    AHB2 => (AHB2ENR, ahb2enr, AHB2LPENR, ahb2lpenr, AHB2RSTR, ahb2rstr, "Advanced High-performance Bus 2 (AHB2) registers"),
    //#[cfg(any(feature = "fsmc", feature = "fmc"))]
    //AHB3 => (AHB3ENR, ahb3enr, AHB3LPENR, ahb3lpenr, AHB3RSTR, ahb3rstr, "Advanced High-performance Bus 3 (AHB3) registers"),
}

/// AMBA High-performance Bus 3 (AHB3) registers
#[cfg(any(feature = "fsmc", feature = "fmc"))]
pub struct AHB3 {
    _0: (),
}

#[cfg(any(feature = "fsmc", feature = "fmc"))]
impl AHB3 {
    #[inline(always)]
    fn enr(rcc: &RccRB) -> &rcc::AHB3ENR {
        &rcc.ahb3enr
    }
    #[cfg(feature = "fmc")]
    #[inline(always)]
    fn lpenr(rcc: &RccRB) -> &rcc::AHB3LPENR {
        &rcc.ahb3lpenr
    }
    #[inline(always)]
    fn rstr(rcc: &RccRB) -> &rcc::AHB3RSTR {
        &rcc.ahb3rstr
    }
}

impl BusClock for AHB1 {
    fn clock(clocks: &Clocks) -> Hertz {
        clocks.hclk
    }
}

#[cfg(not(feature = "gpio-f410"))]
impl BusClock for AHB2 {
    fn clock(clocks: &Clocks) -> Hertz {
        clocks.hclk
    }
}

#[cfg(any(feature = "fsmc", feature = "fmc"))]
impl BusClock for AHB3 {
    fn clock(clocks: &Clocks) -> Hertz {
        clocks.hclk
    }
}

impl BusClock for APB1 {
    fn clock(clocks: &Clocks) -> Hertz {
        clocks.pclk1
    }
}

impl BusClock for APB2 {
    fn clock(clocks: &Clocks) -> Hertz {
        clocks.pclk2
    }
}

impl BusTimerClock for APB1 {
    fn timer_clock(clocks: &Clocks) -> Hertz {
        clocks.timclk1
    }
}

impl BusTimerClock for APB2 {
    fn timer_clock(clocks: &Clocks) -> Hertz {
        clocks.timclk2
    }
}

impl RccExt for RCC {
    fn constrain(self) -> Rcc {
        Rcc {
            cfgr: CFGR {
                hse: None,
                hse_bypass: false,
                hclk: None,
                pclk1: None,
                pclk2: None,
                sysclk: None,
                pll48clk: false,
                i2s_ckin: None,
                #[cfg(any(
                    feature = "gpio-f401",
                    feature = "gpio-f410",
                    feature = "gpio-f411",
                    feature = "gpio-f417",
                    feature = "gpio-f427",
                    feature = "gpio-f469",
                ))]
                i2s_clk: None,
                #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
                i2s_apb1_clk: None,
                #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
                i2s_apb2_clk: None,
                #[cfg(feature = "sai1")]
                sai1_clk: None,
                #[cfg(feature = "sai1")]
                sai2_clk: None,
            },
        }
    }
}

/// Constrained RCC peripheral
pub struct Rcc {
    pub cfgr: CFGR,
}

/// Built-in high speed clock frequency
pub const HSI: u32 = 16_000_000; // Hz

#[cfg(any(
    feature = "gpio-f401",
    feature = "gpio-f410",
    feature = "gpio-f411",
    feature = "gpio-f412",
    feature = "gpio-f413",
    feature = "gpio-f417",
    feature = "gpio-f427",
    feature = "gpio-f469",
))]
/// Minimum system clock frequency
pub const SYSCLK_MIN: u32 = 24_000_000;

#[cfg(feature = "gpio-f446")]
/// Minimum system clock frequency
pub const SYSCLK_MIN: u32 = 12_500_000;

#[cfg(feature = "gpio-f401")]
/// Maximum system clock frequency
pub const SYSCLK_MAX: u32 = 84_000_000;

#[cfg(feature = "gpio-f417")]
/// Maximum system clock frequency
pub const SYSCLK_MAX: u32 = 168_000_000;

#[cfg(any(
    feature = "gpio-f410",
    feature = "gpio-f411",
    feature = "gpio-f412",
    feature = "gpio-f413",
))]
/// Maximum system clock frequency
pub const SYSCLK_MAX: u32 = 100_000_000;

#[cfg(any(feature = "gpio-f427", feature = "gpio-f446", feature = "gpio-f469"))]
/// Maximum system clock frequency
pub const SYSCLK_MAX: u32 = 180_000_000;

#[cfg(any(
    feature = "gpio-f401",
    feature = "gpio-f410",
    feature = "gpio-f411",
    feature = "gpio-f412",
    feature = "gpio-f413",
))]
/// Maximum APB2 peripheral clock frequency
pub const PCLK2_MAX: u32 = SYSCLK_MAX;

#[cfg(not(any(
    feature = "gpio-f401",
    feature = "gpio-f410",
    feature = "gpio-f411",
    feature = "gpio-f412",
    feature = "gpio-f413",
)))]
/// Maximum APB2 peripheral clock frequency
pub const PCLK2_MAX: u32 = SYSCLK_MAX / 2;

/// Maximum APB1 peripheral clock frequency
pub const PCLK1_MAX: u32 = PCLK2_MAX / 2;

pub struct CFGR {
    hse: Option<u32>,
    hse_bypass: bool,
    hclk: Option<u32>,
    pclk1: Option<u32>,
    pclk2: Option<u32>,
    sysclk: Option<u32>,
    pll48clk: bool,

    i2s_ckin: Option<u32>,
    #[cfg(any(
        feature = "gpio-f401",
        feature = "gpio-f410",
        feature = "gpio-f411",
        feature = "gpio-f417",
        feature = "gpio-f427",
        feature = "gpio-f469",
    ))]
    i2s_clk: Option<u32>,
    #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
    i2s_apb1_clk: Option<u32>,
    #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
    i2s_apb2_clk: Option<u32>,
    #[cfg(feature = "sai1")]
    sai1_clk: Option<u32>,
    #[cfg(feature = "sai1")]
    sai2_clk: Option<u32>,
}

impl CFGR {
    /// Uses HSE (external oscillator) instead of HSI (internal RC oscillator) as the clock source.
    /// Will result in a hang if an external oscillator is not connected or it fails to start.
    pub fn use_hse(mut self, freq: Hertz) -> Self {
        self.hse = Some(freq.raw());
        self
    }

    /// Bypasses the high-speed external oscillator and uses an external clock input on the OSC_IN
    /// pin.
    ///
    /// For this configuration, the OSC_IN pin should be connected to a clock source with a
    /// frequency specified in the call to use_hse(), and the OSC_OUT pin should not be connected.
    ///
    /// This function has no effect unless use_hse() is also called.
    pub fn bypass_hse_oscillator(self) -> Self {
        Self {
            hse_bypass: true,
            ..self
        }
    }

    pub fn hclk(mut self, freq: Hertz) -> Self {
        self.hclk = Some(freq.raw());
        self
    }

    pub fn pclk1(mut self, freq: Hertz) -> Self {
        self.pclk1 = Some(freq.raw());
        self
    }

    pub fn pclk2(mut self, freq: Hertz) -> Self {
        self.pclk2 = Some(freq.raw());
        self
    }

    pub fn sysclk(mut self, freq: Hertz) -> Self {
        self.sysclk = Some(freq.raw());
        self
    }

    pub fn require_pll48clk(mut self) -> Self {
        self.pll48clk = true;
        self
    }

    /// Declares that the selected frequency is available at the I2S clock input pin (I2S_CKIN).
    ///
    /// If this frequency matches the requested SAI or I2S frequencies, the external I2S clock is
    /// used to generate the clocks.
    pub fn i2s_ckin(mut self, freq: Hertz) -> Self {
        self.i2s_ckin = Some(freq.raw());
        self
    }

    /// Selects an I2S clock frequency and enables the I2S clock.
    #[cfg(any(
        feature = "gpio-f401",
        feature = "gpio-f410",
        feature = "gpio-f411",
        feature = "gpio-f417",
        feature = "gpio-f427",
        feature = "gpio-f469",
    ))]
    pub fn i2s_clk(mut self, freq: Hertz) -> Self {
        self.i2s_clk = Some(freq.raw());
        self
    }

    /// Selects an I2S clock frequency for the first set of I2S instancesand enables the I2S clock.
    #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
    pub fn i2s_apb1_clk(mut self, freq: Hertz) -> Self {
        self.i2s_apb1_clk = Some(freq.raw());
        self
    }

    /// Selects an I2S clock frequency for the second set of I2S instances and enables the I2S clock.
    #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
    pub fn i2s_apb2_clk(mut self, freq: Hertz) -> Self {
        self.i2s_apb2_clk = Some(freq.raw());
        self
    }

    /// Selects a SAIA clock frequency and enables the SAIA clock.
    #[cfg(any(feature = "gpio-f413", feature = "gpio-f427", feature = "gpio-f469"))]
    pub fn saia_clk(mut self, freq: Hertz) -> Self {
        self.sai1_clk = Some(freq.raw());
        self
    }

    /// Selects a SAIB clock frequency and enables the SAIB clock.
    #[cfg(any(feature = "gpio-f413", feature = "gpio-f427", feature = "gpio-f469"))]
    pub fn saib_clk(mut self, freq: Hertz) -> Self {
        self.sai2_clk = Some(freq.raw());
        self
    }

    /// Selects a SAI1 clock frequency and enables the SAI1 clock.
    #[cfg(feature = "gpio-f446")]
    pub fn sai1_clk(mut self, freq: Hertz) -> Self {
        self.sai1_clk = Some(freq.raw());
        self
    }

    /// Selects a SAI2 clock frequency and enables the SAI2 clock.
    #[cfg(feature = "gpio-f446")]
    pub fn sai2_clk(mut self, freq: Hertz) -> Self {
        self.sai2_clk = Some(freq.raw());
        self
    }
    #[cfg(feature = "gpio-f410")]
    #[inline(always)]
    fn pll_setup(&self, pllsrcclk: u32, pllsysclk: Option<u32>) -> PllSetup {
        let i2s_clocks = self.i2s_clocks();

        let main_pll = if let Some(i2s_clk) = i2s_clocks.pll_i2s_clk {
            // The I2S frequency is generated by the main PLL. The frequency needs to be accurate,
            // so we need an expensive full PLL configuration search.
            MainPll::setup_with_i2s(
                pllsrcclk,
                self.hse.is_some(),
                pllsysclk,
                self.pll48clk,
                i2s_clk,
            )
        } else {
            MainPll::fast_setup(pllsrcclk, self.hse.is_some(), pllsysclk, self.pll48clk)
        };

        PllSetup {
            use_pll: main_pll.use_pll,
            pllsysclk: main_pll.pllsysclk,
            pll48clk: main_pll.pll48clk,
            i2s: i2s_clocks.real(main_pll.plli2sclk, self.i2s_ckin),
        }
    }

    #[cfg(feature = "gpio-f413")]
    #[inline(always)]
    fn pll_setup(&self, pllsrcclk: u32, pllsysclk: Option<u32>) -> PllSetup {
        let rcc = unsafe { &*RCC::ptr() };

        let i2s_clocks = self.i2s_clocks();
        let sai_clocks = self.sai_clocks();

        let main_pll = MainPll::fast_setup(pllsrcclk, self.hse.is_some(), pllsysclk, self.pll48clk);

        let (i2s_pll, real_sai_clk) = if let Some(i2s_clk) = i2s_clocks.pll_i2s_clk {
            // Currently, we only support generating SAI/PLL clocks with the I2S PLL. This is only
            // really usable when the frequencies are identical or the I2S frequency is a multiple of
            // the SAI frequency. Therefore, we just optimize the PLL for the I2S frequency and then
            // derive the SAI frequency from the I2S frequency.
            let i2s_pll = I2sPll::setup(pllsrcclk, Some(i2s_clk));

            if let Some(sai_clk) = sai_clocks.pll_sai_clk {
                let div = u32::min(
                    u32::max((i2s_pll.plli2sclk.unwrap() + (sai_clk >> 1)) / sai_clk, 1),
                    31,
                );
                rcc.dckcfgr.modify(|_, w| w.plli2sdivr().bits(div as u8));
                let real_sai_clk = sai_clk / div;
                (i2s_pll, Some(real_sai_clk))
            } else {
                (i2s_pll, None)
            }
        } else if let Some(pll_sai_clk) = sai_clocks.pll_sai_clk {
            // We try all divider values to get the best approximation of the requested frequency.
            // NOTE: STM32F413/423 have a different divider range than other models!
            let (i2s_pll, real_sai_clk, div) = (1..31)
                .map(|div| {
                    let i2s_pll = I2sPll::setup(pllsrcclk, Some(pll_sai_clk * div));
                    let real_clk = i2s_pll.plli2sclk.unwrap() / div;
                    (i2s_pll, real_clk, div)
                })
                .min_by_key(|(_, real_clk, _)| (*real_clk as i32 - pll_sai_clk as i32).abs())
                .unwrap();
            rcc.dckcfgr.modify(|_, w| w.plli2sdivr().bits(div as u8));
            (i2s_pll, Some(real_sai_clk))
        } else {
            (I2sPll::unused(), None)
        };

        PllSetup {
            use_pll: main_pll.use_pll,
            use_i2spll: i2s_pll.use_pll,
            pllsysclk: main_pll.pllsysclk,
            pll48clk: main_pll.pll48clk,
            i2s: i2s_clocks.real(i2s_pll.plli2sclk, self.i2s_ckin),
            sai: sai_clocks.real(real_sai_clk, self.i2s_ckin),
        }
    }

    #[cfg(any(feature = "gpio-f411", feature = "gpio-f412", feature = "gpio-f446"))]
    #[inline(always)]
    fn pll_setup(&self, pllsrcclk: u32, pllsysclk: Option<u32>) -> PllSetup {
        let i2s_clocks = self.i2s_clocks();
        #[cfg(feature = "gpio-f446")]
        let sai_clocks = self.sai_clocks();

        // All PLLs are completely independent.
        let main_pll = MainPll::fast_setup(pllsrcclk, self.hse.is_some(), pllsysclk, self.pll48clk);
        let i2s_pll = I2sPll::setup(pllsrcclk, i2s_clocks.pll_i2s_clk);
        #[cfg(feature = "gpio-f446")]
        let sai_pll = SaiPll::setup(pllsrcclk, sai_clocks.pll_sai_clk);

        PllSetup {
            use_pll: main_pll.use_pll,
            use_i2spll: i2s_pll.use_pll,
            #[cfg(feature = "gpio-f446")]
            use_saipll: sai_pll.use_pll,
            pllsysclk: main_pll.pllsysclk,
            pll48clk: main_pll.pll48clk,
            i2s: i2s_clocks.real(i2s_pll.plli2sclk, self.i2s_ckin),
            #[cfg(feature = "gpio-f446")]
            sai: sai_clocks.real(sai_pll.sai_clk, self.i2s_ckin),
        }
    }

    #[cfg(any(
        feature = "gpio-f401",
        feature = "gpio-f417",
        feature = "gpio-f427",
        feature = "gpio-f469",
    ))]
    #[inline(always)]
    fn pll_setup(&self, pllsrcclk: u32, pllsysclk: Option<u32>) -> PllSetup {
        let i2s_clocks = self.i2s_clocks();
        #[cfg(any(feature = "gpio-f427", feature = "gpio-f469"))]
        let sai_clocks = self.sai_clocks();

        // We have separate PLLs, but they share the "M" divider.
        let main_pll = MainPll::fast_setup(pllsrcclk, self.hse.is_some(), pllsysclk, self.pll48clk);
        let i2s_pll = I2sPll::setup_shared_m(pllsrcclk, main_pll.m, i2s_clocks.pll_i2s_clk);
        #[cfg(any(feature = "gpio-f427", feature = "gpio-f469"))]
        let sai_pll =
            SaiPll::setup_shared_m(pllsrcclk, main_pll.m.or(i2s_pll.m), sai_clocks.pll_sai_clk);

        PllSetup {
            use_pll: main_pll.use_pll,
            use_i2spll: i2s_pll.use_pll,
            #[cfg(any(feature = "gpio-f427", feature = "gpio-f469"))]
            use_saipll: sai_pll.use_pll,
            pllsysclk: main_pll.pllsysclk,
            pll48clk: main_pll.pll48clk,
            i2s: i2s_clocks.real(i2s_pll.plli2sclk, self.i2s_ckin),
            #[cfg(any(feature = "gpio-f427", feature = "gpio-f469"))]
            sai: sai_clocks.real(sai_pll.sai_clk, self.i2s_ckin),
        }
    }

    #[cfg(feature = "sai1")]
    fn sai_clocks(&self) -> SaiClocks {
        let sai1_ext = self.sai1_clk.is_some() && self.sai1_clk == self.i2s_ckin;
        #[cfg(not(feature = "gpio-f446"))]
        let sai2_ext = self.sai2_clk.is_some() && self.sai2_clk == self.i2s_ckin;
        // Not the PLL output, but the target clock after the divider.
        let pll_sai_clk = if sai1_ext { None } else { self.sai1_clk };
        // The STM32F446 only supports I2S_CKIN for SAI1.
        #[cfg(feature = "gpio-f446")]
        let pll_sai_clk2 = self.sai2_clk;
        #[cfg(not(feature = "gpio-f446"))]
        let pll_sai_clk2 = if sai2_ext { None } else { self.sai2_clk };
        if pll_sai_clk.is_some() && pll_sai_clk2.is_some() && pll_sai_clk != pll_sai_clk2 {
            panic!("only one SAI PLL frequency implemented");
        }
        SaiClocks {
            sai1_ext,
            #[cfg(not(feature = "gpio-f446"))]
            sai2_ext,
            pll_sai_clk,
        }
    }

    #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
    fn i2s_clocks(&self) -> I2sClocks {
        let i2s_apb1_ext = self.i2s_apb1_clk.is_some() && self.i2s_apb1_clk == self.i2s_ckin;
        let i2s_apb2_ext = self.i2s_apb2_clk.is_some() && self.i2s_apb2_clk == self.i2s_ckin;
        let pll_i2s_clk = if i2s_apb1_ext {
            None
        } else {
            self.i2s_apb1_clk
        };
        let pll_i2s_clk2 = if i2s_apb2_ext {
            None
        } else {
            self.i2s_apb2_clk
        };
        if pll_i2s_clk.is_some() && pll_i2s_clk2.is_some() && pll_i2s_clk != pll_i2s_clk2 {
            panic!("only one I2S PLL frequency implemented");
        }
        I2sClocks {
            i2s_apb1_ext,
            i2s_apb2_ext,
            pll_i2s_clk,
        }
    }

    #[cfg(not(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446")))]
    fn i2s_clocks(&self) -> I2sClocks {
        let i2s_ext = self.i2s_clk.is_some() && self.i2s_clk == self.i2s_ckin;
        let pll_i2s_clk = if i2s_ext { None } else { self.i2s_clk };
        I2sClocks {
            i2s_ext,
            pll_i2s_clk,
        }
    }

    fn flash_setup(sysclk: u32) {
        use crate::pac::FLASH;

        #[cfg(any(
            feature = "gpio-f401",
            feature = "gpio-f417",
            feature = "gpio-f410",
            feature = "gpio-f411",
            feature = "gpio-f412",
            feature = "gpio-f427",
            feature = "gpio-f446",
            feature = "gpio-f469",
        ))]
        let flash_latency_step = 30_000_000;

        #[cfg(feature = "gpio-f413")]
        let flash_latency_step = 25_000_000;

        unsafe {
            let flash = &(*FLASH::ptr());
            // Adjust flash wait states
            flash.acr.modify(|_, w| {
                w.latency().bits(((sysclk - 1) / flash_latency_step) as u8);
                w.prften().set_bit();
                w.icen().set_bit();
                w.dcen().set_bit()
            })
        }
    }

    /// Initialises the hardware according to CFGR state returning a Clocks instance.
    /// Panics if overclocking is attempted.
    pub fn freeze(self) -> Clocks {
        self.freeze_internal(false)
    }

    /// Initialises the hardware according to CFGR state returning a Clocks instance.
    /// Allows overclocking.
    ///
    /// # Safety
    ///
    /// This method does not check if the clocks are bigger or smaller than the officially
    /// recommended.
    pub unsafe fn freeze_unchecked(self) -> Clocks {
        self.freeze_internal(true)
    }

    fn freeze_internal(self, unchecked: bool) -> Clocks {
        let rcc = unsafe { &*RCC::ptr() };

        //let (use_pll, sysclk_on_pll, sysclk, pll48clk) = self.pll_setup();
        let pllsrcclk = self.hse.unwrap_or(HSI);
        let sysclk = self.sysclk.unwrap_or(pllsrcclk);
        let sysclk_on_pll = sysclk != pllsrcclk;

        let plls = self.pll_setup(pllsrcclk, sysclk_on_pll.then_some(sysclk));
        let sysclk = if sysclk_on_pll {
            plls.pllsysclk.unwrap()
        } else {
            sysclk
        };

        assert!(unchecked || !sysclk_on_pll || (SYSCLK_MIN..=SYSCLK_MAX).contains(&sysclk));

        let hclk = self.hclk.unwrap_or(sysclk);
        let (hpre_bits, hpre_div) = match (sysclk + hclk - 1) / hclk {
            0 => unreachable!(),
            1 => (HPRE_A::Div1, 1),
            2 => (HPRE_A::Div2, 2),
            3..=5 => (HPRE_A::Div4, 4),
            6..=11 => (HPRE_A::Div8, 8),
            12..=39 => (HPRE_A::Div16, 16),
            40..=95 => (HPRE_A::Div64, 64),
            96..=191 => (HPRE_A::Div128, 128),
            192..=383 => (HPRE_A::Div256, 256),
            _ => (HPRE_A::Div512, 512),
        };

        // Calculate real AHB clock
        let hclk = sysclk / hpre_div;

        let pclk1 = self
            .pclk1
            .unwrap_or_else(|| core::cmp::min(PCLK1_MAX, hclk));
        let (ppre1_bits, ppre1) = match (hclk + pclk1 - 1) / pclk1 {
            0 => unreachable!(),
            1 => (0b000, 1u8),
            2 => (0b100, 2),
            3..=5 => (0b101, 4),
            6..=11 => (0b110, 8),
            _ => (0b111, 16),
        };

        // Calculate real APB1 clock
        let pclk1 = hclk / u32::from(ppre1);

        assert!(unchecked || pclk1 <= PCLK1_MAX);

        let pclk2 = self
            .pclk2
            .unwrap_or_else(|| core::cmp::min(PCLK2_MAX, hclk));
        let (ppre2_bits, ppre2) = match (hclk + pclk2 - 1) / pclk2 {
            0 => unreachable!(),
            1 => (0b000, 1u8),
            2 => (0b100, 2),
            3..=5 => (0b101, 4),
            6..=11 => (0b110, 8),
            _ => (0b111, 16),
        };

        // Calculate real APB2 clock
        let pclk2 = hclk / u32::from(ppre2);

        assert!(unchecked || pclk2 <= PCLK2_MAX);

        Self::flash_setup(sysclk);

        if self.hse.is_some() {
            // enable HSE and wait for it to be ready
            rcc.cr.modify(|_, w| {
                if self.hse_bypass {
                    w.hsebyp().bypassed();
                }
                w.hseon().set_bit()
            });
            while rcc.cr.read().hserdy().bit_is_clear() {}
        }

        if plls.use_pll {
            // Enable PLL
            rcc.cr.modify(|_, w| w.pllon().set_bit());

            // Enable voltage regulator overdrive if HCLK is above the limit
            #[cfg(any(feature = "gpio-f427", feature = "gpio-f446", feature = "gpio-f469"))]
            if hclk > 168_000_000 {
                // Enable clock for PWR peripheral
                rcc.apb1enr.modify(|_, w| w.pwren().set_bit());

                // Stall the pipeline to work around erratum 2.1.13 (DM00037591)
                cortex_m::asm::dsb();

                let pwr = unsafe { &*crate::pac::PWR::ptr() };
                pwr.cr.modify(|_, w| w.oden().set_bit());
                while pwr.csr.read().odrdy().bit_is_clear() {}
                pwr.cr.modify(|_, w| w.odswen().set_bit());
                while pwr.csr.read().odswrdy().bit_is_clear() {}
            }

            // Wait for PLL to stabilise
            while rcc.cr.read().pllrdy().bit_is_clear() {}
        }

        #[cfg(not(feature = "gpio-f410"))]
        if plls.use_i2spll {
            // Enable PLL.
            rcc.cr.modify(|_, w| w.plli2son().set_bit());

            // Wait for PLL to stabilise
            while rcc.cr.read().plli2srdy().bit_is_clear() {}
        }

        #[cfg(any(feature = "gpio-f427", feature = "gpio-f446", feature = "gpio-f469"))]
        if plls.use_saipll {
            // Enable PLL.
            rcc.cr.modify(|_, w| w.pllsaion().set_bit());

            // Wait for PLL to stabilise
            while rcc.cr.read().pllsairdy().bit_is_clear() {}
        }

        // Select I2S and SAI clocks
        plls.i2s.config_clocksel();
        #[cfg(feature = "sai1")]
        plls.sai.config_clocksel();

        // Set scaling factors
        rcc.cfgr.modify(|_, w| unsafe {
            w.ppre2().bits(ppre2_bits);
            w.ppre1().bits(ppre1_bits);
            w.hpre().variant(hpre_bits)
        });

        // Wait for the new prescalers to kick in
        // "The clocks are divided with the new prescaler factor from 1 to 16 AHB cycles after write"
        cortex_m::asm::delay(16);

        // Select system clock source
        rcc.cfgr.modify(|_, w| {
            w.sw().variant(if sysclk_on_pll {
                SW_A::Pll
            } else if self.hse.is_some() {
                SW_A::Hse
            } else {
                SW_A::Hsi
            })
        });

        let pclk_mul = if ppre1 == 1 { 1 } else { 2 };
        let timclk1 = Hertz::from_raw(pclk1 * pclk_mul);

        let pclk_mul = if ppre2 == 1 { 1 } else { 2 };
        let timclk2 = Hertz::from_raw(pclk2 * pclk_mul);

        let clocks = Clocks {
            hclk: hclk.Hz(),
            pclk1: pclk1.Hz(),
            pclk2: pclk2.Hz(),
            timclk1,
            timclk2,
            sysclk: sysclk.Hz(),
            pll48clk: plls.pll48clk.map(Hertz::from_raw),

            #[cfg(not(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446")))]
            i2s_clk: plls.i2s.i2s_clk.map(Hertz::from_raw),
            #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
            i2s_apb1_clk: plls.i2s.i2s_apb1_clk.map(Hertz::from_raw),
            #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
            i2s_apb2_clk: plls.i2s.i2s_apb2_clk.map(Hertz::from_raw),

            #[cfg(any(feature = "gpio-f413", feature = "gpio-f427", feature = "gpio-f469"))]
            saia_clk: plls.sai.sai1_clk.map(Hertz::from_raw),
            #[cfg(any(feature = "gpio-f413", feature = "gpio-f427", feature = "gpio-f469"))]
            saib_clk: plls.sai.sai2_clk.map(Hertz::from_raw),
            #[cfg(feature = "sai2")]
            sai1_clk: plls.sai.sai1_clk.map(Hertz::from_raw),
            #[cfg(feature = "sai2")]
            sai2_clk: plls.sai.sai2_clk.map(Hertz::from_raw),
        };

        if self.pll48clk {
            assert!(clocks.is_pll48clk_valid());
        }

        clocks
    }
}

#[cfg_attr(feature = "defmt", derive(defmt::Format))]
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
struct PllSetup {
    use_pll: bool,
    #[cfg(not(feature = "gpio-f410"))]
    use_i2spll: bool,
    #[cfg(any(feature = "gpio-f427", feature = "gpio-f446", feature = "gpio-f469"))]
    use_saipll: bool,

    pllsysclk: Option<u32>,
    pll48clk: Option<u32>,

    i2s: RealI2sClocks,

    #[cfg(feature = "sai1")]
    sai: RealSaiClocks,
}

#[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
struct I2sClocks {
    /// True if the clock for the APB1 I2S instances is identical to I2S_CKIN.
    i2s_apb1_ext: bool,
    /// True if the clock for the APB2 I2S instances is identical to I2S_CKIN.
    i2s_apb2_ext: bool,
    /// Target for the I2S PLL output.
    pll_i2s_clk: Option<u32>,
}

#[cfg(not(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446")))]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
struct I2sClocks {
    /// True if the clock for I2S is identical to I2S_CKIN.
    i2s_ext: bool,
    /// Target for the I2S PLL output.
    pll_i2s_clk: Option<u32>,
}

impl I2sClocks {
    #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
    fn real(&self, pll_i2s_clk: Option<u32>, i2s_ckin: Option<u32>) -> RealI2sClocks {
        RealI2sClocks {
            i2s_apb1_ext: self.i2s_apb1_ext,
            i2s_apb2_ext: self.i2s_apb2_ext,
            i2s_apb1_clk: if self.i2s_apb1_ext {
                i2s_ckin
            } else {
                pll_i2s_clk
            },
            i2s_apb2_clk: if self.i2s_apb2_ext {
                i2s_ckin
            } else {
                pll_i2s_clk
            },
        }
    }

    #[cfg(not(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446")))]
    fn real(&self, pll_i2s_clk: Option<u32>, i2s_ckin: Option<u32>) -> RealI2sClocks {
        RealI2sClocks {
            i2s_ext: self.i2s_ext,
            i2s_clk: if self.i2s_ext { i2s_ckin } else { pll_i2s_clk },
        }
    }
}

#[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
struct RealI2sClocks {
    i2s_apb1_ext: bool,
    i2s_apb2_ext: bool,
    i2s_apb1_clk: Option<u32>,
    i2s_apb2_clk: Option<u32>,
}

#[cfg(not(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446")))]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
struct RealI2sClocks {
    i2s_ext: bool,
    i2s_clk: Option<u32>,
}

impl RealI2sClocks {
    fn config_clocksel(&self) {
        let rcc = unsafe { &*RCC::ptr() };

        #[cfg(not(any(
            feature = "gpio-f410",
            feature = "gpio-f412",
            feature = "gpio-f413",
            feature = "gpio-f446",
        )))]
        rcc.cfgr.modify(|_, w| {
            if self.i2s_ext {
                w.i2ssrc().ckin()
            } else {
                w.i2ssrc().plli2s()
            }
        });
        #[cfg(feature = "gpio-f410")]
        rcc.dckcfgr.modify(|_, w| {
            if self.i2s_ext {
                w.i2ssrc().i2s_ckin()
            } else {
                w.i2ssrc().pllclkr()
            }
        });
        #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
        rcc.dckcfgr.modify(|_, w| {
            if self.i2s_apb1_ext {
                w.i2s1src().i2s_ckin()
            } else {
                w.i2s1src().plli2sr()
            };
            if self.i2s_apb2_ext {
                w.i2s2src().i2s_ckin()
            } else {
                w.i2s2src().plli2sr()
            }
        });
    }
}

#[cfg(feature = "sai1")]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
struct SaiClocks {
    /// True if the clock for SAI1 (STM32F446) or SAIA (all other models) is identical to I2S_CKIN.
    sai1_ext: bool,
    /// True if the clock for SAIB is identical to I2S_CKIN.
    #[cfg(not(feature = "gpio-f446"))]
    sai2_ext: bool,
    /// Target for the SAI clock as generated by PLL and SAI clock divider.
    pll_sai_clk: Option<u32>,
}

#[cfg(feature = "sai1")]
impl SaiClocks {
    fn real(&self, pll_sai_clk: Option<u32>, i2s_ckin: Option<u32>) -> RealSaiClocks {
        RealSaiClocks {
            sai1_ext: self.sai1_ext,
            #[cfg(not(feature = "gpio-f446"))]
            sai2_ext: self.sai2_ext,
            sai1_clk: if self.sai1_ext { i2s_ckin } else { pll_sai_clk },
            #[cfg(not(feature = "gpio-f446"))]
            sai2_clk: if self.sai2_ext { i2s_ckin } else { pll_sai_clk },
            #[cfg(feature = "gpio-f446")]
            sai2_clk: pll_sai_clk,
        }
    }
}

#[cfg(feature = "sai1")]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
struct RealSaiClocks {
    sai1_ext: bool,
    #[cfg(not(feature = "gpio-f446"))]
    sai2_ext: bool,
    sai1_clk: Option<u32>,
    sai2_clk: Option<u32>,
}

#[cfg(feature = "sai1")]
impl RealSaiClocks {
    fn config_clocksel(&self) {
        let rcc = unsafe { &*RCC::ptr() };

        // Configure SAI clocks.
        #[cfg(not(feature = "gpio-f446"))]
        rcc.dckcfgr.modify(|_, w| {
            if self.sai1_ext {
                w.sai1asrc().i2s_ckin()
            } else {
                w.sai1asrc().pllsai()
            };
            if self.sai2_ext {
                w.sai1bsrc().i2s_ckin()
            } else {
                w.sai1bsrc().pllsai()
            }
        });

        #[cfg(feature = "gpio-f446")]
        rcc.dckcfgr.modify(|_, w| {
            if self.sai1_ext {
                w.sai1src().i2s_ckin()
            } else {
                w.sai1src().pllsai()
            }
        });
    }
}

/// Frozen clock frequencies
///
/// The existence of this value indicates that the clock configuration can no longer be changed
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub struct Clocks {
    hclk: Hertz,
    pclk1: Hertz,
    pclk2: Hertz,
    timclk1: Hertz,
    timclk2: Hertz,
    sysclk: Hertz,
    pll48clk: Option<Hertz>,

    #[cfg(not(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446")))]
    i2s_clk: Option<Hertz>,
    #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
    i2s_apb1_clk: Option<Hertz>,
    #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
    i2s_apb2_clk: Option<Hertz>,

    #[cfg(any(feature = "gpio-f413", feature = "gpio-f427", feature = "gpio-f469"))]
    saia_clk: Option<Hertz>,
    #[cfg(any(feature = "gpio-f413", feature = "gpio-f427", feature = "gpio-f469"))]
    saib_clk: Option<Hertz>,
    #[cfg(feature = "gpio-f446")]
    sai1_clk: Option<Hertz>,
    #[cfg(feature = "gpio-f446")]
    sai2_clk: Option<Hertz>,
}

impl Clocks {
    /// Returns the frequency of the AHB1
    pub fn hclk(&self) -> Hertz {
        self.hclk
    }

    /// Returns the frequency of the APB1
    pub fn pclk1(&self) -> Hertz {
        self.pclk1
    }

    /// Returns the frequency of the APB2
    pub fn pclk2(&self) -> Hertz {
        self.pclk2
    }

    /// Returns the frequency for timers on APB1
    pub fn timclk1(&self) -> Hertz {
        self.timclk1
    }

    /// Returns the frequency for timers on APB1
    pub fn timclk2(&self) -> Hertz {
        self.timclk2
    }

    /// Returns the system (core) frequency
    pub fn sysclk(&self) -> Hertz {
        self.sysclk
    }

    /// Returns the frequency of the PLL48 clock line
    pub fn pll48clk(&self) -> Option<Hertz> {
        self.pll48clk
    }

    /// Returns true if the PLL48 clock is within USB
    /// specifications. It is required to use the USB functionality.
    pub fn is_pll48clk_valid(&self) -> bool {
        // USB specification allows +-0.25%
        self.pll48clk
            .map(|freq| 48_000_000_u32.abs_diff(freq.raw()) <= 120_000)
            .unwrap_or_default()
    }

    /// Returns the frequency of the I2S clock.
    #[cfg(not(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446")))]
    pub fn i2s_clk(&self) -> Option<Hertz> {
        self.i2s_clk
    }
    /// Returns the frequency of the first I2S clock (for the I2S peripherals on APB1).
    #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
    pub fn i2s_apb1_clk(&self) -> Option<Hertz> {
        self.i2s_apb1_clk
    }
    /// Returns the frequency of the second I2S clock (for the I2S peripherals on APB2).
    #[cfg(any(feature = "gpio-f412", feature = "gpio-f413", feature = "gpio-f446"))]
    pub fn i2s_apb2_clk(&self) -> Option<Hertz> {
        self.i2s_apb2_clk
    }

    /// Returns the frequency of the SAI A clock.
    #[cfg(any(feature = "gpio-f413", feature = "gpio-f427", feature = "gpio-f469"))]
    pub fn saia_clk(&self) -> Option<Hertz> {
        self.saia_clk
    }
    /// Returns the frequency of the SAI B clock.
    #[cfg(any(feature = "gpio-f413", feature = "gpio-f427", feature = "gpio-f469"))]
    pub fn saib_clk(&self) -> Option<Hertz> {
        self.saib_clk
    }
    /// Returns the frequency of the SAI1 clock.
    #[cfg(feature = "gpio-f446")]
    pub fn sai1_clk(&self) -> Option<Hertz> {
        self.sai1_clk
    }
    /// Returns the frequency of the SAI2 clock.
    #[cfg(feature = "gpio-f446")]
    pub fn sai2_clk(&self) -> Option<Hertz> {
        self.sai2_clk
    }
}