7 files changed, 482 insertions, 1 deletions

diff --git a/embassy-rp/Cargo.toml b/embassy-rp/Cargo.toml
index ccb2f6525..bc6f44662 100644
--- a/embassy-rp/Cargo.toml
+++ b/embassy-rp/Cargo.toml
@@ -44,6 +44,7 @@ cortex-m-rt = ">=0.6.15,<0.8"
 cortex-m = "0.7.6"
 critical-section = "1.1"
 futures = { version = "0.3.17", default-features = false, features = ["async-await"] }
+chrono = { version = "0.4", default-features = false, optional = true }
 
 rp2040-pac2 = { git = "https://github.com/embassy-rs/rp2040-pac2", rev="017e3c9007b2d3b6965f0d85b5bf8ce3fa6d7364", features = ["rt"] }
 #rp2040-pac2 = { path = "../../rp2040-pac2", features = ["rt"] }
diff --git a/embassy-rp/src/clocks.rs b/embassy-rp/src/clocks.rs
index 3ad1e5d82..1c446f389 100644
--- a/embassy-rp/src/clocks.rs
+++ b/embassy-rp/src/clocks.rs
@@ -122,7 +122,7 @@ pub(crate) fn clk_peri_freq() -> u32 {
     125_000_000
 }
 
-pub(crate) fn _clk_rtc_freq() -> u32 {
+pub(crate) fn clk_rtc_freq() -> u32 {
     46875
 }
 
diff --git a/embassy-rp/src/lib.rs b/embassy-rp/src/lib.rs
index aebbbf567..730354557 100644
--- a/embassy-rp/src/lib.rs
+++ b/embassy-rp/src/lib.rs
@@ -7,6 +7,7 @@ pub(crate) mod fmt;
 pub mod dma;
 pub mod gpio;
 pub mod interrupt;
+pub mod rtc;
 pub mod spi;
 pub mod timer;
 pub mod uart;
@@ -84,6 +85,8 @@ embassy_hal_common::peripherals! {
     DMA_CH11,
 
     USB,
+
+    RTC,
 }
 
 #[link_section = ".boot2"]
diff --git a/embassy-rp/src/rtc/datetime_chrono.rs b/embassy-rp/src/rtc/datetime_chrono.rs
new file mode 100644
index 000000000..b3c78dd47
--- /dev/null
+++ b/embassy-rp/src/rtc/datetime_chrono.rs
@@ -0,0 +1,62 @@
+use chrono::{Datelike, Timelike};
+
+use crate::pac::rtc::regs::{Rtc0, Rtc1, Setup0, Setup1};
+
+/// Alias for [`chrono::NaiveDateTime`]
+pub type DateTime = chrono::NaiveDateTime;
+/// Alias for [`chrono::Weekday`]
+pub type DayOfWeek = chrono::Weekday;
+
+/// Errors regarding the [`DateTime`] and [`DateTimeFilter`] structs.
+///
+/// [`DateTimeFilter`]: struct.DateTimeFilter.html
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum Error {
+    /// The [DateTime] has an invalid year. The year must be between 0 and 4095.
+    InvalidYear,
+    /// The [DateTime] contains an invalid date.
+    InvalidDate,
+    /// The [DateTime] contains an invalid time.
+    InvalidTime,
+}
+
+pub(super) fn day_of_week_to_u8(dotw: DayOfWeek) -> u8 {
+    dotw.num_days_from_sunday() as u8
+}
+
+pub(crate) fn validate_datetime(dt: &DateTime) -> Result<(), Error> {
+    if dt.year() < 0 || dt.year() > 4095 {
+        // rp2040 can't hold these years
+        Err(Error::InvalidYear)
+    } else {
+        // The rest of the chrono date is assumed to be valid
+        Ok(())
+    }
+}
+
+pub(super) fn write_setup_0(dt: &DateTime, w: &mut Setup0) {
+    w.set_year(dt.year() as u16);
+    w.set_month(dt.month() as u8);
+    w.set_day(dt.day() as u8);
+}
+
+pub(super) fn write_setup_1(dt: &DateTime, w: &mut Setup1) {
+    w.set_dotw(dt.weekday().num_days_from_sunday() as u8);
+    w.set_hour(dt.hour() as u8);
+    w.set_min(dt.minute() as u8);
+    w.set_sec(dt.second() as u8);
+}
+
+pub(super) fn datetime_from_registers(rtc_0: Rtc0, rtc_1: Rtc1) -> Result<DateTime, Error> {
+    let year = rtc_1.year() as i32;
+    let month = rtc_1.month() as u32;
+    let day = rtc_1.day() as u32;
+
+    let hour = rtc_0.hour() as u32;
+    let minute = rtc_0.min() as u32;
+    let second = rtc_0.sec() as u32;
+
+    let date = chrono::NaiveDate::from_ymd_opt(year, month, day).ok_or(Error::InvalidDate)?;
+    let time = chrono::NaiveTime::from_hms_opt(hour, minute, second).ok_or(Error::InvalidTime)?;
+    Ok(DateTime::new(date, time))
+}
diff --git a/embassy-rp/src/rtc/datetime_no_deps.rs b/embassy-rp/src/rtc/datetime_no_deps.rs
new file mode 100644
index 000000000..92770e984
--- /dev/null
+++ b/embassy-rp/src/rtc/datetime_no_deps.rs
@@ -0,0 +1,127 @@
+use crate::pac::rtc::regs::{Rtc0, Rtc1, Setup0, Setup1};
+
+/// Errors regarding the [`DateTime`] and [`DateTimeFilter`] structs.
+///
+/// [`DateTimeFilter`]: struct.DateTimeFilter.html
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum Error {
+    /// The [DateTime] contains an invalid year value. Must be between `0..=4095`.
+    InvalidYear,
+    /// The [DateTime] contains an invalid month value. Must be between `1..=12`.
+    InvalidMonth,
+    /// The [DateTime] contains an invalid day value. Must be between `1..=31`.
+    InvalidDay,
+    /// The [DateTime] contains an invalid day of week. Must be between `0..=6` where 0 is Sunday.
+    InvalidDayOfWeek(
+        /// The value of the DayOfWeek that was given.
+        u8,
+    ),
+    /// The [DateTime] contains an invalid hour value. Must be between `0..=23`.
+    InvalidHour,
+    /// The [DateTime] contains an invalid minute value. Must be between `0..=59`.
+    InvalidMinute,
+    /// The [DateTime] contains an invalid second value. Must be between `0..=59`.
+    InvalidSecond,
+}
+
+/// Structure containing date and time information
+pub struct DateTime {
+    /// 0..4095
+    pub year: u16,
+    /// 1..12, 1 is January
+    pub month: u8,
+    /// 1..28,29,30,31 depending on month
+    pub day: u8,
+    ///
+    pub day_of_week: DayOfWeek,
+    /// 0..23
+    pub hour: u8,
+    /// 0..59
+    pub minute: u8,
+    /// 0..59
+    pub second: u8,
+}
+
+/// A day of the week
+#[repr(u8)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Ord, PartialOrd, Hash)]
+#[allow(missing_docs)]
+pub enum DayOfWeek {
+    Sunday = 0,
+    Monday = 1,
+    Tuesday = 2,
+    Wednesday = 3,
+    Thursday = 4,
+    Friday = 5,
+    Saturday = 6,
+}
+
+fn day_of_week_from_u8(v: u8) -> Result<DayOfWeek, Error> {
+    Ok(match v {
+        0 => DayOfWeek::Sunday,
+        1 => DayOfWeek::Monday,
+        2 => DayOfWeek::Tuesday,
+        3 => DayOfWeek::Wednesday,
+        4 => DayOfWeek::Thursday,
+        5 => DayOfWeek::Friday,
+        6 => DayOfWeek::Saturday,
+        x => return Err(Error::InvalidDayOfWeek(x)),
+    })
+}
+
+pub(super) fn day_of_week_to_u8(dotw: DayOfWeek) -> u8 {
+    dotw as u8
+}
+
+pub(super) fn validate_datetime(dt: &DateTime) -> Result<(), Error> {
+    if dt.year > 4095 {
+        Err(Error::InvalidYear)
+    } else if dt.month < 1 || dt.month > 12 {
+        Err(Error::InvalidMonth)
+    } else if dt.day < 1 || dt.day > 31 {
+        Err(Error::InvalidDay)
+    } else if dt.hour > 23 {
+        Err(Error::InvalidHour)
+    } else if dt.minute > 59 {
+        Err(Error::InvalidMinute)
+    } else if dt.second > 59 {
+        Err(Error::InvalidSecond)
+    } else {
+        Ok(())
+    }
+}
+
+pub(super) fn write_setup_0(dt: &DateTime, w: &mut Setup0) {
+    w.set_year(dt.year);
+    w.set_month(dt.month);
+    w.set_day(dt.day);
+}
+
+pub(super) fn write_setup_1(dt: &DateTime, w: &mut Setup1) {
+    w.set_dotw(dt.day_of_week as u8);
+    w.set_hour(dt.hour);
+    w.set_min(dt.minute);
+    w.set_sec(dt.second);
+}
+
+pub(super) fn datetime_from_registers(rtc_0: Rtc0, rtc_1: Rtc1) -> Result<DateTime, Error> {
+    let year = rtc_1.year();
+    let month = rtc_1.month();
+    let day = rtc_1.day();
+
+    let day_of_week = rtc_0.dotw();
+    let hour = rtc_0.hour();
+    let minute = rtc_0.min();
+    let second = rtc_0.sec();
+
+    let day_of_week = day_of_week_from_u8(day_of_week)?;
+    Ok(DateTime {
+        year,
+        month,
+        day,
+        day_of_week,
+        hour,
+        minute,
+        second,
+    })
+}
diff --git a/embassy-rp/src/rtc/filter.rs b/embassy-rp/src/rtc/filter.rs
new file mode 100644
index 000000000..d4a3bab2f
--- /dev/null
+++ b/embassy-rp/src/rtc/filter.rs
@@ -0,0 +1,100 @@
+use super::DayOfWeek;
+use crate::pac::rtc::regs::{IrqSetup0, IrqSetup1};
+
+/// A filter used for [`RealTimeClock::schedule_alarm`].
+///
+/// [`RealTimeClock::schedule_alarm`]: struct.RealTimeClock.html#method.schedule_alarm
+#[derive(Default)]
+pub struct DateTimeFilter {
+    /// The year that this alarm should trigger on, `None` if the RTC alarm should not trigger on a year value.
+    pub year: Option<u16>,
+    /// The month that this alarm should trigger on, `None` if the RTC alarm should not trigger on a month value.
+    pub month: Option<u8>,
+    /// The day that this alarm should trigger on, `None` if the RTC alarm should not trigger on a day value.
+    pub day: Option<u8>,
+    /// The day of week that this alarm should trigger on, `None` if the RTC alarm should not trigger on a day of week value.
+    pub day_of_week: Option<DayOfWeek>,
+    /// The hour that this alarm should trigger on, `None` if the RTC alarm should not trigger on a hour value.
+    pub hour: Option<u8>,
+    /// The minute that this alarm should trigger on, `None` if the RTC alarm should not trigger on a minute value.
+    pub minute: Option<u8>,
+    /// The second that this alarm should trigger on, `None` if the RTC alarm should not trigger on a second value.
+    pub second: Option<u8>,
+}
+
+impl DateTimeFilter {
+    /// Set a filter on the given year
+    pub fn year(mut self, year: u16) -> Self {
+        self.year = Some(year);
+        self
+    }
+    /// Set a filter on the given month
+    pub fn month(mut self, month: u8) -> Self {
+        self.month = Some(month);
+        self
+    }
+    /// Set a filter on the given day
+    pub fn day(mut self, day: u8) -> Self {
+        self.day = Some(day);
+        self
+    }
+    /// Set a filter on the given day of the week
+    pub fn day_of_week(mut self, day_of_week: DayOfWeek) -> Self {
+        self.day_of_week = Some(day_of_week);
+        self
+    }
+    /// Set a filter on the given hour
+    pub fn hour(mut self, hour: u8) -> Self {
+        self.hour = Some(hour);
+        self
+    }
+    /// Set a filter on the given minute
+    pub fn minute(mut self, minute: u8) -> Self {
+        self.minute = Some(minute);
+        self
+    }
+    /// Set a filter on the given second
+    pub fn second(mut self, second: u8) -> Self {
+        self.second = Some(second);
+        self
+    }
+}
+
+// register helper functions
+impl DateTimeFilter {
+    pub(super) fn write_setup_0(&self, w: &mut IrqSetup0) {
+        if let Some(year) = self.year {
+            w.set_year_ena(true);
+
+            w.set_year(year);
+        }
+        if let Some(month) = self.month {
+            w.set_month_ena(true);
+            w.set_month(month);
+        }
+        if let Some(day) = self.day {
+            w.set_day_ena(true);
+            w.set_day(day);
+        }
+    }
+    pub(super) fn write_setup_1(&self, w: &mut IrqSetup1) {
+        if let Some(day_of_week) = self.day_of_week {
+            w.set_dotw_ena(true);
+            let bits = super::datetime::day_of_week_to_u8(day_of_week);
+
+            w.set_dotw(bits);
+        }
+        if let Some(hour) = self.hour {
+            w.set_hour_ena(true);
+            w.set_hour(hour);
+        }
+        if let Some(minute) = self.minute {
+            w.set_min_ena(true);
+            w.set_min(minute);
+        }
+        if let Some(second) = self.second {
+            w.set_sec_ena(true);
+            w.set_sec(second);
+        }
+    }
+}
diff --git a/embassy-rp/src/rtc/mod.rs b/embassy-rp/src/rtc/mod.rs
new file mode 100644
index 000000000..7f3bbbe73
--- /dev/null
+++ b/embassy-rp/src/rtc/mod.rs
@@ -0,0 +1,188 @@
+mod filter;
+
+use embassy_hal_common::{into_ref, Peripheral, PeripheralRef};
+
+pub use self::filter::DateTimeFilter;
+
+#[cfg_attr(feature = "chrono", path = "datetime_chrono.rs")]
+#[cfg_attr(not(feature = "chrono"), path = "datetime_no_deps.rs")]
+mod datetime;
+
+pub use self::datetime::{DateTime, DayOfWeek, Error as DateTimeError};
+use crate::clocks::clk_rtc_freq;
+
+/// A reference to the real time clock of the system
+pub struct RealTimeClock<'d, T: Instance> {
+    inner: PeripheralRef<'d, T>,
+}
+
+impl<'d, T: Instance> RealTimeClock<'d, T> {
+    /// Create a new instance of the real time clock, with the given date as an initial value.
+    ///
+    /// # Errors
+    ///
+    /// Will return `RtcError::InvalidDateTime` if the datetime is not a valid range.
+    pub fn new(inner: impl Peripheral<P = T> + 'd, initial_date: DateTime) -> Result<Self, RtcError> {
+        into_ref!(inner);
+
+        // Set the RTC divider
+        unsafe {
+            inner
+                .regs()
+                .clkdiv_m1()
+                .write(|w| w.set_clkdiv_m1(clk_rtc_freq() as u16 - 1))
+        };
+
+        let mut result = Self { inner };
+        result.set_leap_year_check(true); // should be on by default, make sure this is the case.
+        result.set_datetime(initial_date)?;
+        Ok(result)
+    }
+
+    /// Enable or disable the leap year check. The rp2040 chip will always add a Feb 29th on every year that is divisable by 4, but this may be incorrect (e.g. on century years). This function allows you to disable this check.
+    ///
+    /// Leap year checking is enabled by default.
+    pub fn set_leap_year_check(&mut self, leap_year_check_enabled: bool) {
+        unsafe {
+            self.inner
+                .regs()
+                .ctrl()
+                .modify(|w| w.set_force_notleapyear(!leap_year_check_enabled))
+        };
+    }
+
+    /// Checks to see if this RealTimeClock is running
+    pub fn is_running(&self) -> bool {
+        unsafe { self.inner.regs().ctrl().read().rtc_active() }
+    }
+
+    /// Set the datetime to a new value.
+    ///
+    /// # Errors
+    ///
+    /// Will return `RtcError::InvalidDateTime` if the datetime is not a valid range.
+    pub fn set_datetime(&mut self, t: DateTime) -> Result<(), RtcError> {
+        self::datetime::validate_datetime(&t).map_err(RtcError::InvalidDateTime)?;
+
+        // disable RTC while we configure it
+        unsafe {
+            self.inner.regs().ctrl().modify(|w| w.set_rtc_enable(false));
+            while self.inner.regs().ctrl().read().rtc_active() {
+                core::hint::spin_loop();
+            }
+
+            self.inner.regs().setup_0().write(|w| {
+                self::datetime::write_setup_0(&t, w);
+            });
+            self.inner.regs().setup_1().write(|w| {
+                self::datetime::write_setup_1(&t, w);
+            });
+
+            // Load the new datetime and re-enable RTC
+            self.inner.regs().ctrl().write(|w| w.set_load(true));
+            self.inner.regs().ctrl().write(|w| w.set_rtc_enable(true));
+            while !self.inner.regs().ctrl().read().rtc_active() {
+                core::hint::spin_loop();
+            }
+        }
+        Ok(())
+    }
+
+    /// 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> {
+        if !self.is_running() {
+            return Err(RtcError::NotRunning);
+        }
+
+        let rtc_0 = unsafe { self.inner.regs().rtc_0().read() };
+        let rtc_1 = unsafe { self.inner.regs().rtc_1().read() };
+
+        self::datetime::datetime_from_registers(rtc_0, rtc_1).map_err(RtcError::InvalidDateTime)
+    }
+
+    /// Disable the alarm that was scheduled with [`schedule_alarm`].
+    ///
+    /// [`schedule_alarm`]: #method.schedule_alarm
+    pub fn disable_alarm(&mut self) {
+        unsafe {
+            self.inner.regs().irq_setup_0().modify(|s| s.set_match_ena(false));
+
+            while self.inner.regs().irq_setup_0().read().match_active() {
+                core::hint::spin_loop();
+            }
+        }
+    }
+
+    /// Schedule an alarm. The `filter` determines at which point in time this alarm is set.
+    ///
+    /// Keep in mind that the filter only triggers on the specified time. If you want to schedule this alarm every minute, you have to call:
+    /// ```no_run
+    /// # #[cfg(feature = "chrono")]
+    /// # fn main() { }
+    /// # #[cfg(not(feature = "chrono"))]
+    /// # fn main() {
+    /// # use embassy_rp::rtc::{RealTimeClock, DateTimeFilter};
+    /// # let mut real_time_clock: RealTimeClock = unsafe { core::mem::zeroed() };
+    /// let now = real_time_clock.now().unwrap();
+    /// real_time_clock.schedule_alarm(
+    ///     DateTimeFilter::default()
+    ///         .minute(if now.minute == 59 { 0 } else { now.minute + 1 })
+    /// );
+    /// # }
+    /// ```
+    pub fn schedule_alarm(&mut self, filter: DateTimeFilter) {
+        self.disable_alarm();
+
+        unsafe {
+            self.inner.regs().irq_setup_0().write(|w| {
+                filter.write_setup_0(w);
+            });
+            self.inner.regs().irq_setup_1().write(|w| {
+                filter.write_setup_1(w);
+            });
+
+            // Set the enable bit and check if it is set
+            self.inner.regs().irq_setup_0().modify(|w| w.set_match_ena(true));
+            while !self.inner.regs().irq_setup_0().read().match_active() {
+                core::hint::spin_loop();
+            }
+        }
+    }
+
+    /// Clear the interrupt. This should be called every time the `RTC_IRQ` interrupt is triggered,
+    /// or the next [`schedule_alarm`] will never fire.
+    ///
+    /// [`schedule_alarm`]: #method.schedule_alarm
+    pub fn clear_interrupt(&mut self) {
+        self.disable_alarm();
+    }
+}
+
+/// Errors that can occur on methods on [RtcClock]
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum RtcError {
+    /// An invalid DateTime was given or stored on the hardware.
+    InvalidDateTime(DateTimeError),
+
+    /// The RTC clock is not running
+    NotRunning,
+}
+
+mod sealed {
+    pub trait Instance {
+        fn regs(&self) -> crate::pac::rtc::Rtc;
+    }
+}
+
+pub trait Instance: sealed::Instance {}
+
+impl sealed::Instance for crate::peripherals::RTC {
+    fn regs(&self) -> crate::pac::rtc::Rtc {
+        crate::pac::RTC
+    }
+}
+impl Instance for crate::peripherals::RTC {}