Do not enable OTP write protect unless ENABLE_OTP_WP=1 is passed during make.

Author: dgarske

docs/flash-OTP.md

@@ -92,6 +92,7 @@ make keytools
 5) Setup the OTP keystore
 
   Flash the OTP keystore primer:
+  - Run `make otp`
   - Flash `./tools/keytools/otp/otp-keystore-primer.bin` to `0x08000000`
   - Disconnect the tool and hit reset button
   - The primer will run and flash keystore.c to OTP and enable write protection on those blocks

tools/keytools/otp/Makefile

@@ -32,6 +32,10 @@ CC=$(CROSS_COMPILE)gcc
 OBJCOPY?=$(CROSS_COMPILE)objcopy
 SIZE?=$(CROSS_COMPILE)size
 
+ifeq ($(ENABLE_OTP_WP),1)
+	CFLAGS+=-DENABLE_OTP_WP
+endif
+
 all: otp-keystore-primer.bin otp-keystore-gen
 
 otp-keystore-gen: otp-keystore-gen.c
@@ -56,7 +60,7 @@ stm32h5.o: ../../../hal/stm32h5.c
 	$(Q)$(CC) $(CFLAGS) -c -o $@ $<
 
 
-	
+
 
 clean:
 	$(Q)rm -rf $(PRI_KS_OBJS) *.bin *.elf

tools/keytools/otp/otp-keystore-primer.c

@@ -59,10 +59,13 @@ void main(void)
                 sizeof(struct keystore_slot));
     }
 
-    /* Protect the OTP area just written */
     tot_len = OTP_HDR_SIZE + n_keys * SIZEOF_KEYSTORE_SLOT;
-    hal_flash_otp_set_readonly(FLASH_OTP_BASE, tot_len);
 
+#ifdef ENABLE_OTP_WP
+    /* Protect the OTP area just written */
+    hal_flash_otp_set_readonly(FLASH_OTP_BASE, tot_len);
+#endif
+    (void)tot_len;
 
     /* Done! */
     while(1)