4 files changed, 182 insertions, 1 deletions

diff --git a/embassy-stm32/src/flash/mod.rs b/embassy-stm32/src/flash/mod.rs
index 9d7861816..8c6ca2471 100644
--- a/embassy-stm32/src/flash/mod.rs
+++ b/embassy-stm32/src/flash/mod.rs
@@ -101,10 +101,11 @@ pub enum FlashBank {
 #[cfg_attr(flash_h7ab, path = "h7.rs")]
 #[cfg_attr(flash_u5, path = "u5.rs")]
 #[cfg_attr(flash_h50, path = "h50.rs")]
+#[cfg_attr(flash_u0, path = "u0.rs")]
 #[cfg_attr(
     not(any(
         flash_l0, flash_l1, flash_l4, flash_wl, flash_wb, flash_f0, flash_f1, flash_f3, flash_f4, flash_f7, flash_g0,
-        flash_g4, flash_h7, flash_h7ab, flash_u5, flash_h50
+        flash_g4, flash_h7, flash_h7ab, flash_u5, flash_h50, flash_u0
     )),
     path = "other.rs"
 )]
diff --git a/embassy-stm32/src/flash/u0.rs b/embassy-stm32/src/flash/u0.rs
new file mode 100644
index 000000000..dfc5a2f76
--- /dev/null
+++ b/embassy-stm32/src/flash/u0.rs
@@ -0,0 +1,96 @@
+use core::ptr::write_volatile;
+use core::sync::atomic::{fence, Ordering};
+
+use cortex_m::interrupt;
+
+use super::{FlashRegion, FlashSector, FLASH_REGIONS, WRITE_SIZE};
+use crate::flash::Error;
+use crate::pac;
+
+pub(crate) const fn is_default_layout() -> bool {
+    true
+}
+
+pub(crate) const fn get_flash_regions() -> &'static [&'static FlashRegion] {
+    &FLASH_REGIONS
+}
+
+pub(crate) unsafe fn lock() {
+    pac::FLASH.cr().modify(|w| w.set_lock(true));
+}
+pub(crate) unsafe fn unlock() {
+    // Wait, while the memory interface is busy.
+    while pac::FLASH.sr().read().bsy1() {}
+
+    // Unlock flash
+    if pac::FLASH.cr().read().lock() {
+        pac::FLASH.keyr().write(|w| w.set_key(0x4567_0123));
+        pac::FLASH.keyr().write(|w| w.set_key(0xCDEF_89AB));
+    }
+}
+
+pub(crate) unsafe fn enable_blocking_write() {
+    assert_eq!(0, WRITE_SIZE % 4);
+    pac::FLASH.cr().write(|w| w.set_pg(true));
+}
+
+pub(crate) unsafe fn disable_blocking_write() {
+    pac::FLASH.cr().write(|w| w.set_pg(false));
+}
+
+pub(crate) unsafe fn blocking_write(start_address: u32, buf: &[u8; WRITE_SIZE]) -> Result<(), Error> {
+    let mut address = start_address;
+    for val in buf.chunks(4) {
+        write_volatile(address as *mut u32, u32::from_le_bytes(val.try_into().unwrap()));
+        address += val.len() as u32;
+
+        // prevents parallelism errors
+        fence(Ordering::SeqCst);
+    }
+
+    wait_ready_blocking()
+}
+
+pub(crate) unsafe fn blocking_erase_sector(sector: &FlashSector) -> Result<(), Error> {
+    let idx = (sector.start - super::FLASH_BASE as u32) / super::BANK1_REGION.erase_size as u32;
+    while pac::FLASH.sr().read().bsy1() {}
+    clear_all_err();
+
+    interrupt::free(|_| {
+        pac::FLASH.cr().modify(|w| {
+            w.set_per(true);
+            w.set_pnb(idx as u8);
+            w.set_strt(true);
+        });
+    });
+
+    let ret: Result<(), Error> = wait_ready_blocking();
+    pac::FLASH.cr().modify(|w| w.set_per(false));
+    ret
+}
+
+pub(crate) unsafe fn wait_ready_blocking() -> Result<(), Error> {
+    while pac::FLASH.sr().read().bsy1() {}
+
+    let sr = pac::FLASH.sr().read();
+
+    if sr.progerr() {
+        return Err(Error::Prog);
+    }
+
+    if sr.wrperr() {
+        return Err(Error::Protected);
+    }
+
+    if sr.pgaerr() {
+        return Err(Error::Unaligned);
+    }
+
+    Ok(())
+}
+
+pub(crate) unsafe fn clear_all_err() {
+    // read and write back the same value.
+    // This clears all "write 1 to clear" bits.
+    pac::FLASH.sr().modify(|_| {});
+}
diff --git a/examples/stm32u0/src/bin/flash.rs b/examples/stm32u0/src/bin/flash.rs
new file mode 100644
index 000000000..01b80a76b
--- /dev/null
+++ b/examples/stm32u0/src/bin/flash.rs
@@ -0,0 +1,43 @@
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::flash::Flash;
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_stm32::init(Default::default());
+    info!("Hello World!");
+
+    let addr: u32 = 0x40000 - 2 * 1024;
+
+    let mut f = Flash::new_blocking(p.FLASH).into_blocking_regions().bank1_region;
+
+    info!("Reading...");
+    let mut buf = [0u8; 32];
+    unwrap!(f.blocking_read(addr, &mut buf));
+    info!("Read: {=[u8]:x}", buf);
+    info!("Erasing...");
+    unwrap!(f.blocking_erase(addr, addr + 2 * 1024));
+
+    info!("Reading...");
+    let mut buf = [0u8; 32];
+    unwrap!(f.blocking_read(addr, &mut buf));
+    info!("Read after erase: {=[u8]:x}", buf);
+
+    info!("Writing...");
+    unwrap!(f.blocking_write(
+        addr,
+        &[
+            1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29,
+            30, 31, 32
+        ]
+    ));
+
+    info!("Reading...");
+    let mut buf = [0u8; 32];
+    unwrap!(f.blocking_read(addr, &mut buf));
+    info!("Read: {=[u8]:x}", buf);
+}
diff --git a/examples/stm32u0/src/bin/wdt.rs b/examples/stm32u0/src/bin/wdt.rs
new file mode 100644
index 000000000..f6276e2e9
--- /dev/null
+++ b/examples/stm32u0/src/bin/wdt.rs
@@ -0,0 +1,41 @@
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_stm32::gpio::{Level, Output, Speed};
+use embassy_stm32::wdg::IndependentWatchdog;
+use embassy_time::Timer;
+use {defmt_rtt as _, panic_probe as _};
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_stm32::init(Default::default());
+    info!("Hello World!");
+
+    let mut led = Output::new(p.PA5, Level::High, Speed::Low);
+
+    let mut wdt = IndependentWatchdog::new(p.IWDG, 1_000_000);
+    wdt.unleash();
+
+    let mut i = 0;
+
+    loop {
+        info!("high");
+        led.set_high();
+        Timer::after_millis(300).await;
+
+        info!("low");
+        led.set_low();
+        Timer::after_millis(300).await;
+
+        // Pet watchdog for 5 iterations and then stop.
+        // MCU should restart in 1 second after the last pet.
+        if i < 5 {
+            info!("Petting watchdog");
+            wdt.pet();
+        }
+
+        i += 1;
+    }
+}