[ion] Create method to lock PCB versions on old boards

ion/include/ion.h

@@ -3,6 +3,7 @@
 
 #include <ion/backlight.h>
 #include <ion/battery.h>
+#include <ion/board.h>
 #include <ion/clipboard.h>
 #include <ion/console.h>
 #include <ion/display.h>

ion/include/ion/board.h

@@ -0,0 +1,12 @@
+#ifndef ION_BOARD_H
+#define ION_BOARD_H
+
+namespace Ion {
+namespace Board {
+
+void lockUnlockedPCBVersion();
+
+}
+}
+
+#endif

ion/src/device/n0100/drivers/board.cpp

@@ -242,6 +242,8 @@ void writePCBVersion(PCBVersion) {}
 
 void lockPCBVersion() {}
 
+bool pcbVersionIsLocked() { return true; }
+
 }
 }
 }

ion/src/device/n0110/drivers/board.cpp

@@ -385,7 +385,8 @@ PCBVersion pcbVersion() {
    * way, flashing the PCB version can be done last. */
   return PCB_LATEST;
 #else
-  return readPCBVersionInMemory();
+  PCBVersion version = readPCBVersionInMemory();
+  return (version == alternateBlankVersion ? 0 : version);
 #endif
 }
 
@@ -405,6 +406,10 @@ void lockPCBVersion() {
   InternalFlash::WriteMemory(destination, &zero, sizeof(zero));
 }
 
+bool pcbVersionIsLocked() {
+  return *reinterpret_cast<const uint8_t *>(InternalFlash::Config::OTPLocksAddress + pcbVersionOTPIndex) == 0;
+}
+
 }
 }
 }

ion/src/device/shared/drivers/board.cpp

@@ -93,3 +93,26 @@ void setClockFrequency(Frequency f) {
 }
 }
 }
+
+namespace Ion {
+namespace Board {
+
+using namespace Device::Board;
+
+void lockUnlockedPCBVersion() {
+  if (pcbVersionIsLocked()) {
+    return;
+  }
+  /* PCB version is unlocked : the device is a N0110 that has been
+   * produced prior to the pcb revision. */
+  PCBVersion version = pcbVersion();
+  if (version != 0) {
+    /* Some garbage has been written in OTP0. We overwrite it fully, which is
+     * interepreted as blank. */
+    writePCBVersion(alternateBlankVersion);
+  }
+  lockPCBVersion();
+}
+
+}
+}

ion/src/device/shared/drivers/board.h

@@ -26,11 +26,17 @@ void setStandardFrequency(Frequency f);
 void setClockFrequency(Frequency f);
 
 typedef uint32_t PCBVersion;
+/* On N0110 released before the PCB revision, OTP0 is supposed to be blank and
+ * unlocked. However, such a device with something written in OTP0 will be
+ * unable to configure Vbus properly. In this case, and if OTP0 is still
+ * unlocked, we fully write OTP0 and treat it the same as fully blank. */
+constexpr PCBVersion alternateBlankVersion = -1;
 
 PCBVersion pcbVersion();
 PCBVersion readPCBVersionInMemory();
 void writePCBVersion(PCBVersion version);
 void lockPCBVersion();
+bool pcbVersionIsLocked();
 
 }
 }

ion/src/shared/dummy/board.cpp

@@ -0,0 +1,4 @@
+#include <ion/board.h>
+
+void Ion::Board::lockUnlockedPCBVersion() {
+}

ion/src/simulator/Makefile

@@ -1,5 +1,6 @@
 ion_src += $(addprefix ion/src/shared/dummy/, \
   backlight.cpp \
+  board.cpp \
   battery.cpp \
   display.cpp \
   exam_mode.cpp \