From 3616d68aaa0d41bd489295942c57e29a43338dac Mon Sep 17 00:00:00 2001
From: Andres Vahter <andres@vahter.me>
Date: Tue, 10 Oct 2023 12:48:21 +0300
Subject: [PATCH] stm32 flash: check lock bit before unlocking

It hardfaults if already unlocked flash is unlocked again.
---
 embassy-stm32/src/flash/f0.rs |  6 ++++--
 embassy-stm32/src/flash/f3.rs |  6 ++++--
 embassy-stm32/src/flash/f4.rs |  6 ++++--
 embassy-stm32/src/flash/f7.rs |  6 ++++--
 embassy-stm32/src/flash/g0.rs |  6 ++++--
 embassy-stm32/src/flash/h7.rs | 12 ++++++++----
 embassy-stm32/src/flash/l.rs  | 18 ++++++++++++------
 7 files changed, 40 insertions(+), 20 deletions(-)

diff --git a/embassy-stm32/src/flash/f0.rs b/embassy-stm32/src/flash/f0.rs
index d011522be..1ab8435a0 100644
--- a/embassy-stm32/src/flash/f0.rs
+++ b/embassy-stm32/src/flash/f0.rs
@@ -19,8 +19,10 @@ pub(crate) unsafe fn lock() {
 }
 
 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));
+    if pac::FLASH.cr().read().lock() {
+        pac::FLASH.keyr().write(|w| w.set_fkeyr(0x4567_0123));
+        pac::FLASH.keyr().write(|w| w.set_fkeyr(0xCDEF_89AB));
+    }
 }
 
 pub(crate) unsafe fn enable_blocking_write() {
diff --git a/embassy-stm32/src/flash/f3.rs b/embassy-stm32/src/flash/f3.rs
index 065369f64..7e6d7ca26 100644
--- a/embassy-stm32/src/flash/f3.rs
+++ b/embassy-stm32/src/flash/f3.rs
@@ -19,8 +19,10 @@ pub(crate) unsafe fn lock() {
 }
 
 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));
+    if pac::FLASH.cr().read().lock() {
+        pac::FLASH.keyr().write(|w| w.set_fkeyr(0x4567_0123));
+        pac::FLASH.keyr().write(|w| w.set_fkeyr(0xCDEF_89AB));
+    }
 }
 
 pub(crate) unsafe fn enable_blocking_write() {
diff --git a/embassy-stm32/src/flash/f4.rs b/embassy-stm32/src/flash/f4.rs
index 913950fe5..81deaa179 100644
--- a/embassy-stm32/src/flash/f4.rs
+++ b/embassy-stm32/src/flash/f4.rs
@@ -228,8 +228,10 @@ pub(crate) unsafe fn lock() {
 }
 
 pub(crate) unsafe fn unlock() {
-    pac::FLASH.keyr().write(|w| w.set_key(0x45670123));
-    pac::FLASH.keyr().write(|w| w.set_key(0xCDEF89AB));
+    if pac::FLASH.cr().read().lock() {
+        pac::FLASH.keyr().write(|w| w.set_key(0x45670123));
+        pac::FLASH.keyr().write(|w| w.set_key(0xCDEF89AB));
+    }
 }
 
 pub(crate) unsafe fn enable_write() {
diff --git a/embassy-stm32/src/flash/f7.rs b/embassy-stm32/src/flash/f7.rs
index 3a5bdf9c5..b52231ca8 100644
--- a/embassy-stm32/src/flash/f7.rs
+++ b/embassy-stm32/src/flash/f7.rs
@@ -19,8 +19,10 @@ pub(crate) unsafe fn lock() {
 }
 
 pub(crate) unsafe fn unlock() {
-    pac::FLASH.keyr().write(|w| w.set_key(0x4567_0123));
-    pac::FLASH.keyr().write(|w| w.set_key(0xCDEF_89AB));
+    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() {
diff --git a/embassy-stm32/src/flash/g0.rs b/embassy-stm32/src/flash/g0.rs
index 3a4576016..19a388970 100644
--- a/embassy-stm32/src/flash/g0.rs
+++ b/embassy-stm32/src/flash/g0.rs
@@ -24,8 +24,10 @@ pub(crate) unsafe fn unlock() {
     while pac::FLASH.sr().read().bsy() {}
 
     // Unlock flash
-    pac::FLASH.keyr().write(|w| w.set_keyr(0x4567_0123));
-    pac::FLASH.keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+    if pac::FLASH.cr().read().lock() {
+        pac::FLASH.keyr().write(|w| w.set_keyr(0x4567_0123));
+        pac::FLASH.keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+    }
 }
 
 pub(crate) unsafe fn enable_blocking_write() {
diff --git a/embassy-stm32/src/flash/h7.rs b/embassy-stm32/src/flash/h7.rs
index 625bf13fc..b064fd6ea 100644
--- a/embassy-stm32/src/flash/h7.rs
+++ b/embassy-stm32/src/flash/h7.rs
@@ -26,11 +26,15 @@ pub(crate) unsafe fn lock() {
 }
 
 pub(crate) unsafe fn unlock() {
-    pac::FLASH.bank(0).keyr().write(|w| w.set_keyr(0x4567_0123));
-    pac::FLASH.bank(0).keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+    if pac::FLASH.bank(0).cr().read().lock() {
+        pac::FLASH.bank(0).keyr().write(|w| w.set_keyr(0x4567_0123));
+        pac::FLASH.bank(0).keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+    }
     if is_dual_bank() {
-        pac::FLASH.bank(1).keyr().write(|w| w.set_keyr(0x4567_0123));
-        pac::FLASH.bank(1).keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+        if pac::FLASH.bank(1).cr().read().lock() {
+            pac::FLASH.bank(1).keyr().write(|w| w.set_keyr(0x4567_0123));
+            pac::FLASH.bank(1).keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+        }
     }
 }
 
diff --git a/embassy-stm32/src/flash/l.rs b/embassy-stm32/src/flash/l.rs
index 24dcf99bc..1db0da923 100644
--- a/embassy-stm32/src/flash/l.rs
+++ b/embassy-stm32/src/flash/l.rs
@@ -28,17 +28,23 @@ pub(crate) unsafe fn lock() {
 pub(crate) unsafe fn unlock() {
     #[cfg(any(flash_wl, flash_wb, flash_l4))]
     {
-        pac::FLASH.keyr().write(|w| w.set_keyr(0x4567_0123));
-        pac::FLASH.keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+        if pac::FLASH.cr().read().lock() {
+            pac::FLASH.keyr().write(|w| w.set_keyr(0x4567_0123));
+            pac::FLASH.keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+        }
     }
 
     #[cfg(any(flash_l0, flash_l1))]
     {
-        pac::FLASH.pekeyr().write(|w| w.set_pekeyr(0x89ABCDEF));
-        pac::FLASH.pekeyr().write(|w| w.set_pekeyr(0x02030405));
+        if pac::FLASH.pecr().read().pelock() {
+            pac::FLASH.pekeyr().write(|w| w.set_pekeyr(0x89ABCDEF));
+            pac::FLASH.pekeyr().write(|w| w.set_pekeyr(0x02030405));
+        }
 
-        pac::FLASH.prgkeyr().write(|w| w.set_prgkeyr(0x8C9DAEBF));
-        pac::FLASH.prgkeyr().write(|w| w.set_prgkeyr(0x13141516));
+        if pac::FLASH.pecr().read().prglock() {
+            pac::FLASH.prgkeyr().write(|w| w.set_prgkeyr(0x8C9DAEBF));
+            pac::FLASH.prgkeyr().write(|w| w.set_prgkeyr(0x13141516));
+        }
     }
 }