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Merge pull request #4313 from snakehand/main
U5: Enable MSI auto calibration and compute frequencies
This commit is contained in:
Dario Nieuwenhuis
GitHub
commit
ff29d61b31
@ -5,7 +5,7 @@ pub use crate::pac::rcc::vals::{
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Hpre as AHBPrescaler, Msirange, Msirange as MSIRange, Plldiv as PllDiv, Pllm as PllPreDiv, Plln as PllMul,
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Pllsrc as PllSource, Ppre as APBPrescaler, Sw as Sysclk,
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};
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use crate::pac::rcc::vals::{Hseext, Msirgsel, Pllmboost, Pllrge};
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use crate::pac::rcc::vals::{Hseext, Msipllfast, Msipllsel, Msirgsel, Pllmboost, Pllrge};
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#[cfg(all(peri_usb_otg_hs))]
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pub use crate::pac::{syscfg::vals::Usbrefcksel, SYSCFG};
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use crate::pac::{FLASH, PWR, RCC};
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@ -64,6 +64,46 @@ pub struct Pll {
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pub divr: Option<PllDiv>,
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}
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#[derive(Clone, Copy, PartialEq)]
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pub enum MsiAutoCalibration {
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/// MSI auto-calibration is disabled
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Disabled,
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/// MSIS is given priority for auto-calibration
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MSIS,
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/// MSIK is given priority for auto-calibration
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MSIK,
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/// MSIS with fast mode (always on)
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MsisFast,
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/// MSIK with fast mode (always on)
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MsikFast,
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}
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impl MsiAutoCalibration {
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const fn default() -> Self {
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MsiAutoCalibration::Disabled
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}
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fn base_mode(&self) -> Self {
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match self {
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MsiAutoCalibration::Disabled => MsiAutoCalibration::Disabled,
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MsiAutoCalibration::MSIS => MsiAutoCalibration::MSIS,
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MsiAutoCalibration::MSIK => MsiAutoCalibration::MSIK,
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MsiAutoCalibration::MsisFast => MsiAutoCalibration::MSIS,
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MsiAutoCalibration::MsikFast => MsiAutoCalibration::MSIK,
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}
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}
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fn is_fast(&self) -> bool {
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matches!(self, MsiAutoCalibration::MsisFast | MsiAutoCalibration::MsikFast)
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}
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}
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impl Default for MsiAutoCalibration {
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fn default() -> Self {
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Self::default()
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}
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}
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#[derive(Clone, Copy)]
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pub struct Config {
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// base clock sources
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@ -95,6 +135,7 @@ pub struct Config {
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/// Per-peripheral kernel clock selection muxes
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pub mux: super::mux::ClockMux,
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pub auto_calibration: MsiAutoCalibration,
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}
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impl Config {
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@ -116,6 +157,7 @@ impl Config {
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voltage_range: VoltageScale::RANGE1,
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ls: crate::rcc::LsConfig::new(),
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mux: super::mux::ClockMux::default(),
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auto_calibration: MsiAutoCalibration::default(),
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}
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}
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}
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@ -131,7 +173,42 @@ pub(crate) unsafe fn init(config: Config) {
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PWR.vosr().modify(|w| w.set_vos(config.voltage_range));
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while !PWR.vosr().read().vosrdy() {}
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let msis = config.msis.map(|range| {
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let lse_calibration_freq = if config.auto_calibration != MsiAutoCalibration::Disabled {
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// LSE must be configured and peripherals clocked for MSI auto-calibration
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let lse_config = config
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.ls
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.lse
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.clone()
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.expect("LSE must be configured for MSI auto-calibration");
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assert!(lse_config.peripherals_clocked);
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// Expect less than +/- 5% deviation for LSE frequency
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if (31_100..=34_400).contains(&lse_config.frequency.0) {
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// Check that the calibration is applied to an active clock
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match (
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config.auto_calibration.base_mode(),
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config.msis.is_some(),
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config.msik.is_some(),
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) {
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(MsiAutoCalibration::MSIS, true, _) => {
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// MSIS is active and using LSE for auto-calibration
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Some(lse_config.frequency)
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}
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(MsiAutoCalibration::MSIK, _, true) => {
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// MSIK is active and using LSE for auto-calibration
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Some(lse_config.frequency)
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}
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// improper configuration
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_ => panic!("MSIx auto-calibration is enabled for a source that has not been configured."),
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}
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} else {
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panic!("LSE frequency more than 5% off from 32.768 kHz, cannot use for MSI auto-calibration");
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}
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} else {
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None
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};
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let mut msis = config.msis.map(|range| {
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// Check MSI output per RM0456 § 11.4.10
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match config.voltage_range {
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VoltageScale::RANGE4 => {
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@ -156,11 +233,21 @@ pub(crate) unsafe fn init(config: Config) {
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w.set_msipllen(false);
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w.set_msison(true);
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});
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let msis = if let (Some(freq), MsiAutoCalibration::MSIS) =
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(lse_calibration_freq, config.auto_calibration.base_mode())
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{
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// Enable the MSIS auto-calibration feature
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RCC.cr().modify(|w| w.set_msipllsel(Msipllsel::MSIS));
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RCC.cr().modify(|w| w.set_msipllen(true));
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calculate_calibrated_msi_frequency(range, freq)
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} else {
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msirange_to_hertz(range)
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};
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while !RCC.cr().read().msisrdy() {}
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msirange_to_hertz(range)
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msis
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});
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let msik = config.msik.map(|range| {
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let mut msik = config.msik.map(|range| {
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// Check MSI output per RM0456 § 11.4.10
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match config.voltage_range {
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VoltageScale::RANGE4 => {
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@ -184,10 +271,44 @@ pub(crate) unsafe fn init(config: Config) {
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RCC.cr().modify(|w| {
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w.set_msikon(true);
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});
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let msik = if let (Some(freq), MsiAutoCalibration::MSIK) =
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(lse_calibration_freq, config.auto_calibration.base_mode())
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{
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// Enable the MSIK auto-calibration feature
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RCC.cr().modify(|w| w.set_msipllsel(Msipllsel::MSIK));
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RCC.cr().modify(|w| w.set_msipllen(true));
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calculate_calibrated_msi_frequency(range, freq)
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} else {
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msirange_to_hertz(range)
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};
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while !RCC.cr().read().msikrdy() {}
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msirange_to_hertz(range)
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msik
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});
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if let Some(lse_freq) = lse_calibration_freq {
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// If both MSIS and MSIK are enabled, we need to check if they are using the same internal source.
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if let (Some(msis_range), Some(msik_range)) = (config.msis, config.msik) {
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if (msis_range as u8 >> 2) == (msik_range as u8 >> 2) {
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// Clock source is shared, both will be auto calibrated, recalculate other frequency
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match config.auto_calibration.base_mode() {
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MsiAutoCalibration::MSIS => {
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msik = Some(calculate_calibrated_msi_frequency(msik_range, lse_freq));
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}
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MsiAutoCalibration::MSIK => {
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msis = Some(calculate_calibrated_msi_frequency(msis_range, lse_freq));
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}
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_ => {}
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}
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}
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}
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// Check if Fast mode should be used
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if config.auto_calibration.is_fast() {
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RCC.cr().modify(|w| {
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w.set_msipllfast(Msipllfast::FAST);
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});
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}
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}
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let hsi = config.hsi.then(|| {
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RCC.cr().modify(|w| w.set_hsion(true));
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while !RCC.cr().read().hsirdy() {}
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@ -514,3 +635,37 @@ fn init_pll(instance: PllInstance, config: Option<Pll>, input: &PllInput, voltag
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PllOutput { p, q, r }
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}
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/// Fraction structure for MSI auto-calibration
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/// Represents the multiplier as numerator/denominator that LSE frequency is multiplied by
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#[derive(Debug, Clone, Copy)]
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struct MsiFraction {
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numerator: u32,
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denominator: u32,
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}
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impl MsiFraction {
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const fn new(numerator: u32, denominator: u32) -> Self {
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Self { numerator, denominator }
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}
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/// Calculate the calibrated frequency given an LSE frequency
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fn calculate_frequency(&self, lse_freq: Hertz) -> Hertz {
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Hertz(lse_freq.0 * self.numerator / self.denominator)
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}
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}
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fn get_msi_calibration_fraction(range: Msirange) -> MsiFraction {
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// Exploiting the MSIx internals to make calculations compact
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let denominator = (range as u32 & 0x03) + 1;
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// Base multipliers are deduced from Table 82: MSI oscillator characteristics in data sheet
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let numerator = [1465, 122, 94, 12][range as usize >> 2];
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MsiFraction::new(numerator, denominator)
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}
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/// Calculate the calibrated MSI frequency for a given range and LSE frequency
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fn calculate_calibrated_msi_frequency(range: Msirange, lse_freq: Hertz) -> Hertz {
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let fraction = get_msi_calibration_fraction(range);
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fraction.calculate_frequency(lse_freq)
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}
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