cpu/cortexm_common: extend flashpage API

cpu/cortexm_common/ldscripts/cortexm_base.ld

@@ -207,6 +207,10 @@ SECTIONS
     _sram = ORIGIN(ram);
     _eram = ORIGIN(ram) + LENGTH(ram);
 
+    /* Populate information about rom size */
+    _srom = ORIGIN(rom);
+    _erom = ORIGIN(rom) + LENGTH(rom);
+
     _sbackup_data_load = LOADADDR(.backup.data);
     .backup.data :  ALIGN(4) {
         _sbackup_data = .;
@@ -228,4 +232,8 @@ SECTIONS
         _sheap1 = . ;
         _eheap1 = ORIGIN(bkup_ram) + LENGTH(bkup_ram);
     } > bkup_ram
+
+    .end_fw (NOLOAD) : ALIGN(4) {
+        _end_fw = . ;
+    } > rom
 }

cpu/cortexm_common/periph/flashpage.c

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2021 Freie Universität Berlin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     cpu_cortexm_common
+ * @ingroup     drivers_periph_pm
+ * @{
+ * @file
+ * @brief       common periph/flashpage functions
+ *
+ * @author  Nils Ollrogge <nils.ollrogge@fu-berlin.de>
+ * @}
+ */
+
+#include "periph/flashpage.h"
+
+/**
+ * @brief   Memory markers, defined in the linker script
+ * @{
+ */
+extern uint32_t _end_fw;
+extern uint32_t _erom;
+
+unsigned flashpage_first_free(void)
+{
+    return flashpage_page(&_end_fw) + 1;
+}
+
+unsigned flashpage_last_free(void)
+{
+    return flashpage_page(&_erom) - 1;
+}