Bootrom: Enable serial number from flash

* Add `.ramfunc` section to bootrom loader script
* exclude spiffs functionality from flashmem.h/flashmem.c
   (allows bootrom to use flashmem)
* hide unused tick.h / flashmem.h functions from bootrom
   (not technically necessary; see comments)
* bootrom: add source files, include path, and defines when
  `PLATFORM_DEFS` defines `WITH_FLASH`
* Define `AS_BOOTROM` to indicate code is building for bootrom

bootrom/Makefile

@@ -34,11 +34,17 @@ VERSIONSRC = version_pm3.c
 # THUMBSRC :=
 
 # stdint.h provided locally until GCC 4.5 becomes C99 compliant
-APP_CFLAGS = -I. -ffunction-sections -fdata-sections
+APP_CFLAGS = -I. -ffunction-sections -fdata-sections -DAS_BOOTROM
 
 # stack-protect , no-pie reduces size on Gentoo Hardened 8.2 gcc,  no-common makes sure uninitialized vars don't end up in COMMON area
 APP_CFLAGS += -fno-stack-protector -fno-pie -fno-common
 
+ifneq (,$(findstring WITH_FLASH,$(PLATFORM_DEFS)))
+	APP_CFLAGS += -DWITH_FLASH
+	APP_CFLAGS += -I../common_arm
+    THUMBSRC += flashmem.c ticks.c
+endif
+
 
 # Do not move this inclusion before the definition of {THUMB,ASM,ARM}SRC
 include ../common_arm/Makefile.common

bootrom/bootrom.c

@@ -20,6 +20,10 @@
 #include "clocks.h"
 #include "usb_cdc.h"
 
+#ifdef WITH_FLASH
+#include "flashmem.h"
+#endif
+
 #include "proxmark3_arm.h"
 #define DEBUG 0
 
@@ -214,8 +218,18 @@ static void flash_mode(void) {
     bootrom_unlocked = false;
     uint8_t rx[sizeof(PacketCommandOLD)];
     g_common_area.command = COMMON_AREA_COMMAND_NONE;
-    if (!g_common_area.flags.button_pressed && BUTTON_PRESS())
+    if (!g_common_area.flags.button_pressed && BUTTON_PRESS()) {
         g_common_area.flags.button_pressed = 1;
+    }
+
+#ifdef WITH_FLASH
+    if (FlashInit()) { // checks for existence of flash also ... OK because bootrom was built for devices with flash
+        uint64_t flash_uniqueID = 0;
+        Flash_UniqueID((uint8_t*)&flash_uniqueID);
+        FlashStop();
+        usb_update_serial(flash_uniqueID);
+    }
+#endif
 
     usb_enable();
 

bootrom/ldscript-flash

@@ -53,6 +53,7 @@ SECTIONS
         *(.rodata.*)
         *(.data)
         *(.data.*)
+        *(.ramfunc)
         . = ALIGN(4);
     } >ram AT>bootphase2 :phase2