stm32: add f2 flash support (blocking)

2 files changed, 145 insertions, 2 deletions

diff --git a/embassy-stm32/src/flash/f2.rs b/embassy-stm32/src/flash/f2.rs
new file mode 100644
index 000000000..cdab1fd2d
--- /dev/null
+++ b/embassy-stm32/src/flash/f2.rs
@@ -0,0 +1,142 @@
+use core::ptr::write_volatile;
+use core::sync::atomic::{fence, AtomicBool, Ordering};
+
+use pac::flash::regs::Sr;
+
+use super::{FlashBank, FlashRegion, FlashSector, FLASH_REGIONS, WRITE_SIZE};
+use crate::flash::Error;
+use crate::pac;
+
+static DATA_CACHE_WAS_ENABLED: AtomicBool = AtomicBool::new(false);
+
+impl FlashSector {
+    const fn snb(&self) -> u8 {
+        ((self.bank as u8) << 4) + self.index_in_bank
+    }
+}
+
+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() {
+    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);
+    save_data_cache_state();
+
+    pac::FLASH.cr().write(|w| {
+        w.set_pg(true);
+        w.set_psize(pac::flash::vals::Psize::PSIZE32);
+    });
+}
+
+pub(crate) unsafe fn disable_blocking_write() {
+    pac::FLASH.cr().write(|w| w.set_pg(false));
+    restore_data_cache_state();
+}
+
+pub(crate) unsafe fn blocking_write(start_address: u32, buf: &[u8; WRITE_SIZE]) -> Result<(), Error> {
+    write_start(start_address, buf);
+    blocking_wait_ready()
+}
+
+unsafe fn write_start(start_address: u32, buf: &[u8; WRITE_SIZE]) {
+    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);
+    }
+}
+
+pub(crate) unsafe fn blocking_erase_sector(sector: &FlashSector) -> Result<(), Error> {
+    save_data_cache_state();
+
+    trace!("Blocking erasing sector number {}", sector.snb());
+
+    pac::FLASH.cr().modify(|w| {
+        w.set_ser(true);
+        w.set_snb(sector.snb())
+    });
+
+    pac::FLASH.cr().modify(|w| {
+        w.set_strt(true);
+    });
+
+    let ret: Result<(), Error> = blocking_wait_ready();
+    clear_all_err();
+    restore_data_cache_state();
+    ret
+}
+
+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(|_| {});
+}
+
+unsafe fn blocking_wait_ready() -> Result<(), Error> {
+    loop {
+        let sr = pac::FLASH.sr().read();
+
+        if !sr.bsy() {
+            return get_result(sr);
+        }
+    }
+}
+
+fn get_result(sr: Sr) -> Result<(), Error> {
+    if sr.pgserr() {
+        Err(Error::Seq)
+    } else if sr.pgperr() {
+        Err(Error::Parallelism)
+    } else if sr.pgaerr() {
+        Err(Error::Unaligned)
+    } else if sr.wrperr() {
+        Err(Error::Protected)
+    } else {
+        Ok(())
+    }
+}
+
+fn save_data_cache_state() {
+    let dual_bank = unwrap!(get_flash_regions().last()).bank == FlashBank::Bank2;
+    if dual_bank {
+        // Disable data cache during write/erase if there are two banks, see errata 2.2.12
+        let dcen = pac::FLASH.acr().read().dcen();
+        DATA_CACHE_WAS_ENABLED.store(dcen, Ordering::Relaxed);
+        if dcen {
+            pac::FLASH.acr().modify(|w| w.set_dcen(false));
+        }
+    }
+}
+
+fn restore_data_cache_state() {
+    let dual_bank = unwrap!(get_flash_regions().last()).bank == FlashBank::Bank2;
+    if dual_bank {
+        // Restore data cache if it was enabled
+        let dcen = DATA_CACHE_WAS_ENABLED.load(Ordering::Relaxed);
+        if dcen {
+            // Reset data cache before we enable it again
+            pac::FLASH.acr().modify(|w| w.set_dcrst(true));
+            pac::FLASH.acr().modify(|w| w.set_dcrst(false));
+            pac::FLASH.acr().modify(|w| w.set_dcen(true))
+        }
+    }
+}
diff --git a/embassy-stm32/src/flash/mod.rs b/embassy-stm32/src/flash/mod.rs
index ce2d1a04c..bce638db0 100644
--- a/embassy-stm32/src/flash/mod.rs
+++ b/embassy-stm32/src/flash/mod.rs
@@ -94,6 +94,7 @@ pub enum FlashBank {
 #[cfg_attr(any(flash_l0, flash_l1, flash_l4, flash_wl, flash_wb), path = "l.rs")]
 #[cfg_attr(flash_f0, path = "f0.rs")]
 #[cfg_attr(any(flash_f1, flash_f3), path = "f1f3.rs")]
+#[cfg_attr(flash_f2, path = "f2.rs")]
 #[cfg_attr(flash_f4, path = "f4.rs")]
 #[cfg_attr(flash_f7, path = "f7.rs")]
 #[cfg_attr(any(flash_g0, flash_g4c2, flash_g4c3, flash_g4c4), path = "g.rs")]
@@ -104,8 +105,8 @@ pub enum FlashBank {
 #[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_g4c2, flash_g4c3, flash_g4c4, flash_h7, flash_h7ab, flash_u5, flash_h50, flash_u0
+        flash_l0, flash_l1, flash_l4, flash_wl, flash_wb, flash_f0, flash_f1, flash_f2, flash_f3, flash_f4, flash_f7,
+        flash_g0, flash_g4c2, flash_g4c3, flash_g4c4, flash_h7, flash_h7ab, flash_u5, flash_h50, flash_u0
     )),
     path = "other.rs"
 )]