7 files changed, 162 insertions, 5 deletions

diff --git a/embassy-rp/CHANGELOG.md b/embassy-rp/CHANGELOG.md
index 3b3cb5351..4b0d738a7 100644
--- a/embassy-rp/CHANGELOG.md
+++ b/embassy-rp/CHANGELOG.md
@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 <!-- next-header -->
 ## Unreleased - ReleaseDate
 
+- Add documentation for pio `get_x` about autopush.
 - Fix several minor typos in documentation
 - Add PIO SPI
 - Add PIO I2S input
@@ -114,3 +115,4 @@ Small release fixing a few gnarly bugs, upgrading is strongly recommended.
 - rename the Channel trait to Slice and the PwmPin to PwmChannel
 - i2c: Fix race condition that appears on fast repeated transfers.
 - Add a basic "read to break" function
+
diff --git a/embassy-rp/src/pio/instr.rs b/embassy-rp/src/pio/instr.rs
index b15d507de..304ddb20a 100644
--- a/embassy-rp/src/pio/instr.rs
+++ b/embassy-rp/src/pio/instr.rs
@@ -5,6 +5,10 @@ use crate::pio::{Instance, StateMachine};
 
 impl<'d, PIO: Instance, const SM: usize> StateMachine<'d, PIO, SM> {
     /// Set value of scratch register X.
+    ///
+    /// SAFETY: autopull enabled else it will write undefined data.
+    /// Make sure to have setup the according configuration see
+    /// [shift_out](crate::pio::Config::shift_out) and [auto_fill](crate::pio::ShiftConfig::auto_fill).
     pub unsafe fn set_x(&mut self, value: u32) {
         const OUT: u16 = InstructionOperands::OUT {
             destination: OutDestination::X,
@@ -16,6 +20,10 @@ impl<'d, PIO: Instance, const SM: usize> StateMachine<'d, PIO, SM> {
     }
 
     /// Get value of scratch register X.
+    ///
+    /// SAFETY: autopush enabled else it will read undefined data.
+    /// Make sure to have setup the according configurations see
+    /// [shift_in](crate::pio::Config::shift_in) and [auto_fill](crate::pio::ShiftConfig::auto_fill).
     pub unsafe fn get_x(&mut self) -> u32 {
         const IN: u16 = InstructionOperands::IN {
             source: InSource::X,
@@ -27,6 +35,10 @@ impl<'d, PIO: Instance, const SM: usize> StateMachine<'d, PIO, SM> {
     }
 
     /// Set value of scratch register Y.
+    ///
+    /// SAFETY: autopull enabled else it will write undefined data.
+    /// Make sure to have setup the according configuration see
+    /// [shift_out](crate::pio::Config::shift_out) and [auto_fill](crate::pio::ShiftConfig::auto_fill).
     pub unsafe fn set_y(&mut self, value: u32) {
         const OUT: u16 = InstructionOperands::OUT {
             destination: OutDestination::Y,
@@ -38,6 +50,10 @@ impl<'d, PIO: Instance, const SM: usize> StateMachine<'d, PIO, SM> {
     }
 
     /// Get value of scratch register Y.
+    ///
+    /// SAFETY: autopush enabled else it will read undefined data.
+    /// Make sure to have setup the according configurations see
+    /// [shift_in](crate::pio::Config::shift_in) and [auto_fill](crate::pio::ShiftConfig::auto_fill).
     pub unsafe fn get_y(&mut self) -> u32 {
         const IN: u16 = InstructionOperands::IN {
             source: InSource::Y,
diff --git a/embassy-stm32/CHANGELOG.md b/embassy-stm32/CHANGELOG.md
index 666ee1714..8bd930e79 100644
--- a/embassy-stm32/CHANGELOG.md
+++ b/embassy-stm32/CHANGELOG.md
@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased - ReleaseDate
 
+- fix: flash erase on dual-bank STM32Gxxx
 - feat: Add support for STM32N657X0
 - feat: timer: Add 32-bit timer support to SimplePwm waveform_up method following waveform pattern ([#4717](https://github.com/embassy-rs/embassy/pull/4717))
 - feat: Add support for injected ADC measurements for g4 ([#4840](https://github.com/embassy-rs/embassy/pull/4840))
@@ -56,6 +57,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - chore: Updated stm32-metapac and stm32-data dependencies
 - adc: reogranize and cleanup somewhat. require sample_time to be passed on conversion
 - fix: stm32/i2c v2 slave: prevent misaligned reads, error false positives, and incorrect counts of bytes read/written
+- feat: add flash support for c0 family ([#4874](https://github.com/embassy-rs/embassy/pull/4874))
 
 ## 0.4.0 - 2025-08-26
 
diff --git a/embassy-stm32/src/flash/c.rs b/embassy-stm32/src/flash/c.rs
new file mode 100644
index 000000000..0ad1002b0
--- /dev/null
+++ b/embassy-stm32/src/flash/c.rs
@@ -0,0 +1,131 @@
+use core::ptr::write_volatile;
+use core::sync::atomic::{Ordering, fence};
+
+use cortex_m::interrupt;
+
+use super::{FlashSector, WRITE_SIZE};
+use crate::flash::Error;
+use crate::pac;
+
+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.
+    wait_busy();
+
+    // Unlock flash
+    if pac::FLASH.cr().read().lock() {
+        pac::FLASH.keyr().write_value(0x4567_0123);
+        pac::FLASH.keyr().write_value(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(unwrap!(val.try_into())));
+        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;
+
+    #[cfg(feature = "defmt")]
+    defmt::trace!(
+        "STM32C0 Erase: addr=0x{:08x}, idx={}, erase_size={}",
+        sector.start,
+        idx,
+        super::BANK1_REGION.erase_size
+    );
+
+    wait_busy();
+    clear_all_err();
+
+    // Explicitly unlock before erase
+    unlock();
+
+    interrupt::free(|_| {
+        #[cfg(feature = "defmt")]
+        {
+            let cr_before = pac::FLASH.cr().read();
+            defmt::trace!("FLASH_CR before: 0x{:08x}", cr_before.0);
+        }
+
+        pac::FLASH.cr().modify(|w| {
+            w.set_per(true);
+            w.set_pnb(idx as u8);
+            w.set_strt(true);
+        });
+
+        #[cfg(feature = "defmt")]
+        {
+            let cr_after = pac::FLASH.cr().read();
+            defmt::trace!(
+                "FLASH_CR after: 0x{:08x}, PER={}, PNB={}, STRT={}",
+                cr_after.0,
+                cr_after.per(),
+                cr_after.pnb(),
+                cr_after.strt()
+            );
+        }
+    });
+
+    let ret: Result<(), Error> = wait_ready_blocking();
+
+    // Clear erase bit
+    pac::FLASH.cr().modify(|w| w.set_per(false));
+
+    // Explicitly lock after erase
+    lock();
+
+    // Extra wait to ensure operation completes
+    wait_busy();
+
+    ret
+}
+
+pub(crate) unsafe fn wait_ready_blocking() -> Result<(), Error> {
+    while pac::FLASH.sr().read().bsy() {}
+
+    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(|_| {});
+}
+
+fn wait_busy() {
+    while pac::FLASH.sr().read().bsy() {}
+}
diff --git a/embassy-stm32/src/flash/common.rs b/embassy-stm32/src/flash/common.rs
index b595938a6..60d00e766 100644
--- a/embassy-stm32/src/flash/common.rs
+++ b/embassy-stm32/src/flash/common.rs
@@ -102,7 +102,13 @@ pub(super) unsafe fn blocking_write(
     }
 
     let mut address = base + offset;
-    trace!("Writing {} bytes at 0x{:x}", bytes.len(), address);
+    trace!(
+        "Writing {} bytes at 0x{:x} (base=0x{:x}, offset=0x{:x})",
+        bytes.len(),
+        address,
+        base,
+        offset
+    );
 
     for chunk in bytes.chunks(WRITE_SIZE) {
         write_chunk(address, chunk)?;
diff --git a/embassy-stm32/src/flash/g.rs b/embassy-stm32/src/flash/g.rs
index d026541a4..d7ba2f571 100644
--- a/embassy-stm32/src/flash/g.rs
+++ b/embassy-stm32/src/flash/g.rs
@@ -44,7 +44,6 @@ pub(crate) unsafe fn blocking_write(start_address: u32, buf: &[u8; WRITE_SIZE])
 }
 
 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;
     wait_busy();
     clear_all_err();
 
@@ -54,9 +53,9 @@ pub(crate) unsafe fn blocking_erase_sector(sector: &FlashSector) -> Result<(), E
             #[cfg(any(flash_g0x0, flash_g0x1, flash_g4c3))]
             w.set_bker(sector.bank == crate::flash::FlashBank::Bank2);
             #[cfg(flash_g0x0)]
-            w.set_pnb(idx as u16);
+            w.set_pnb(sector.index_in_bank as u16);
             #[cfg(not(flash_g0x0))]
-            w.set_pnb(idx as u8);
+            w.set_pnb(sector.index_in_bank as u8);
             w.set_strt(true);
         });
     });
diff --git a/embassy-stm32/src/flash/mod.rs b/embassy-stm32/src/flash/mod.rs
index 3e74d857a..39cd9b3a9 100644
--- a/embassy-stm32/src/flash/mod.rs
+++ b/embassy-stm32/src/flash/mod.rs
@@ -99,6 +99,7 @@ compile_error!("The 'eeprom' cfg is enabled for a non-L0/L1 chip family. This is
 #[cfg_attr(flash_f4, path = "f4.rs")]
 #[cfg_attr(flash_f7, path = "f7.rs")]
 #[cfg_attr(any(flash_g0x0, flash_g0x1, flash_g4c2, flash_g4c3, flash_g4c4), path = "g.rs")]
+#[cfg_attr(flash_c0, path = "c.rs")]
 #[cfg_attr(flash_h7, path = "h7.rs")]
 #[cfg_attr(flash_h7ab, path = "h7.rs")]
 #[cfg_attr(any(flash_u5, flash_wba), path = "u5.rs")]
@@ -108,7 +109,7 @@ compile_error!("The 'eeprom' cfg is enabled for a non-L0/L1 chip family. This is
 #[cfg_attr(
     not(any(
         flash_l0, flash_l1, flash_l4, flash_l5, flash_wl, flash_wb, flash_f0, flash_f1, flash_f2, flash_f3, flash_f4,
-        flash_f7, flash_g0x0, flash_g0x1, flash_g4c2, flash_g4c3, flash_g4c4, flash_h7, flash_h7ab, flash_u5,
+        flash_f7, flash_g0x0, flash_g0x1, flash_g4c2, flash_g4c3, flash_g4c4, flash_c0, flash_h7, flash_h7ab, flash_u5,
         flash_wba, flash_h50, flash_u0, flash_h5,
     )),
     path = "other.rs"