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stm32: Add RtcTimeProvider struct to Rtc module

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This struct allows users to acquire the current time without putting `Rtc`
in a mutex and passing that around. This is allowed because reading from the
rtc registers is atomic.
This commit is contained in:
Scott Mabin 2023-09-17 18:04:05 +01:00
parent 75cae09e79
commit 087ef918bf
1 changed files with 36 additions and 15 deletions
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51
embassy-stm32/src/rtc/mod.rs
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@ -82,12 +82,42 @@ impl core::ops::Sub for RtcInstant {
} }
} }
#[non_exhaustive]
pub struct RtcTimeProvider;
impl RtcTimeProvider {
/// Return the current datetime.
///
/// # Errors
///
/// Will return an `RtcError::InvalidDateTime` if the stored value in the system is not a valid [`DayOfWeek`].
pub fn now(&self) -> Result<DateTime, RtcError> {
let r = RTC::regs();
let tr = r.tr().read();
let second = bcd2_to_byte((tr.st(), tr.su()));
let minute = bcd2_to_byte((tr.mnt(), tr.mnu()));
let hour = bcd2_to_byte((tr.ht(), tr.hu()));
// Reading either RTC_SSR or RTC_TR locks the values in the higher-order
// calendar shadow registers until RTC_DR is read.
let dr = r.dr().read();
let weekday = dr.wdu();
let day = bcd2_to_byte((dr.dt(), dr.du()));
let month = bcd2_to_byte((dr.mt() as u8, dr.mu()));
let year = bcd2_to_byte((dr.yt(), dr.yu())) as u16 + 1970_u16;
self::datetime::datetime(year, month, day, weekday, hour, minute, second).map_err(RtcError::InvalidDateTime)
}
}
#[non_exhaustive]
/// RTC Abstraction /// RTC Abstraction
pub struct Rtc { pub struct Rtc {
#[cfg(feature = "low-power")] #[cfg(feature = "low-power")]
stop_time: Mutex<CriticalSectionRawMutex, Cell<Option<RtcInstant>>>, stop_time: Mutex<CriticalSectionRawMutex, Cell<Option<RtcInstant>>>,
} }
#[non_exhaustive]
#[derive(Copy, Clone, PartialEq)] #[derive(Copy, Clone, PartialEq)]
pub struct RtcConfig { pub struct RtcConfig {
/// The subsecond counter frequency; default is 256 /// The subsecond counter frequency; default is 256
@ -155,6 +185,11 @@ impl Rtc {
Hertz(32_768) Hertz(32_768)
} }
/// Acquire a [`RtcTimeProvider`] instance.
pub fn time_provider(&self) -> RtcTimeProvider {
RtcTimeProvider
}
/// Set the datetime to a new value. /// Set the datetime to a new value.
/// ///
/// # Errors /// # Errors
@ -187,21 +222,7 @@ impl Rtc {
/// ///
/// Will return an `RtcError::InvalidDateTime` if the stored value in the system is not a valid [`DayOfWeek`]. /// Will return an `RtcError::InvalidDateTime` if the stored value in the system is not a valid [`DayOfWeek`].
pub fn now(&self) -> Result<DateTime, RtcError> { pub fn now(&self) -> Result<DateTime, RtcError> {
let r = RTC::regs(); RtcTimeProvider.now()
let tr = r.tr().read();
let second = bcd2_to_byte((tr.st(), tr.su()));
let minute = bcd2_to_byte((tr.mnt(), tr.mnu()));
let hour = bcd2_to_byte((tr.ht(), tr.hu()));
// Reading either RTC_SSR or RTC_TR locks the values in the higher-order
// calendar shadow registers until RTC_DR is read.
let dr = r.dr().read();
let weekday = dr.wdu();
let day = bcd2_to_byte((dr.dt(), dr.du()));
let month = bcd2_to_byte((dr.mt() as u8, dr.mu()));
let year = bcd2_to_byte((dr.yt(), dr.yu())) as u16 + 1970_u16;
self::datetime::datetime(year, month, day, weekday, hour, minute, second).map_err(RtcError::InvalidDateTime)
} }
/// Check if daylight savings time is active. /// Check if daylight savings time is active.