From ec7a4fd9cc6284fffbce3c74a82d2942713d4cd4 Mon Sep 17 00:00:00 2001
From: Jaap Prickartz <jaap@tetra.nl>
Date: Sun, 14 May 2023 21:57:31 +0200
Subject: [PATCH] stm32f0 flash implementation

---
 embassy-stm32/src/flash/f0.rs  | 105 +++++++++++++++++++++++++++++++++
 embassy-stm32/src/flash/mod.rs |   3 +-
 2 files changed, 107 insertions(+), 1 deletion(-)
 create mode 100644 embassy-stm32/src/flash/f0.rs

diff --git a/embassy-stm32/src/flash/f0.rs b/embassy-stm32/src/flash/f0.rs
new file mode 100644
index 000000000..033afecd5
--- /dev/null
+++ b/embassy-stm32/src/flash/f0.rs
@@ -0,0 +1,105 @@
+use core::convert::TryInto;
+use core::ptr::write_volatile;
+
+use atomic_polyfill::{fence, Ordering};
+
+use super::{FlashRegion, FlashSector, FLASH_REGIONS, WRITE_SIZE};
+use crate::flash::Error;
+use crate::pac;
+
+pub 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() {
+    pac::FLASH.keyr().write(|w| w.set_fkeyr(0x4567_0123));
+    pac::FLASH.keyr().write(|w| w.set_fkeyr(0xCDEF_89AB));
+}
+
+pub(crate) unsafe fn begin_write() {
+    assert_eq!(0, WRITE_SIZE % 2);
+
+    pac::FLASH.cr().write(|w| w.set_pg(true));
+}
+
+pub(crate) unsafe fn end_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 chunk in buf.chunks(2) {
+        write_volatile(address as *mut u16, u16::from_le_bytes(chunk.try_into().unwrap()));
+        address += chunk.len() as u32;
+
+        // prevents parallelism errors
+        fence(Ordering::SeqCst);
+    }
+
+    blocking_wait_ready()
+}
+
+pub(crate) unsafe fn blocking_erase_sector(sector: &FlashSector) -> Result<(), Error> {
+    pac::FLASH.cr().modify(|w| {
+        w.set_per(true);
+    });
+
+    pac::FLASH.ar().write(|w| w.set_far(sector.start));
+
+    pac::FLASH.cr().modify(|w| {
+        w.set_strt(true);
+    });
+
+    let mut ret: Result<(), Error> = blocking_wait_ready();
+
+    if !pac::FLASH.sr().read().eop() {
+        trace!("FLASH: EOP not set");
+        ret = Err(Error::Prog);
+    } else {
+        pac::FLASH.sr().write(|w| w.set_eop(true));
+    }
+
+    pac::FLASH.cr().modify(|w| w.set_per(false));
+
+    clear_all_err();
+    if ret.is_err() {
+        return ret;
+    }
+    Ok(())
+}
+
+pub(crate) unsafe fn clear_all_err() {
+    pac::FLASH.sr().modify(|w| {
+        if w.pgerr() {
+            w.set_pgerr(true);
+        }
+        if w.wrprt() {
+            w.set_wrprt(true)
+        };
+        if w.eop() {
+            w.set_eop(true);
+        }
+    });
+}
+
+unsafe fn blocking_wait_ready() -> Result<(), Error> {
+    loop {
+        let sr = pac::FLASH.sr().read();
+
+        if !sr.bsy() {
+            if sr.wrprt() {
+                return Err(Error::Protected);
+            }
+
+            if sr.pgerr() {
+                return Err(Error::Seq);
+            }
+
+            return Ok(());
+        }
+    }
+}
diff --git a/embassy-stm32/src/flash/mod.rs b/embassy-stm32/src/flash/mod.rs
index 7d5596b1f..f6efa7753 100644
--- a/embassy-stm32/src/flash/mod.rs
+++ b/embassy-stm32/src/flash/mod.rs
@@ -49,13 +49,14 @@ impl FlashRegion {
 }
 
 #[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(flash_f3, path = "f3.rs")]
 #[cfg_attr(flash_f4, path = "f4.rs")]
 #[cfg_attr(flash_f7, path = "f7.rs")]
 #[cfg_attr(flash_h7, path = "h7.rs")]
 #[cfg_attr(
     not(any(
-        flash_l0, flash_l1, flash_l4, flash_wl, flash_wb, flash_f3, flash_f4, flash_f7, flash_h7
+        flash_l0, flash_l1, flash_l4, flash_wl, flash_wb, flash_f0, flash_f3, flash_f4, flash_f7, flash_h7
     )),
     path = "other.rs"
 )]