ram_pwrdn: Add API for powering up RAM

Add API that powers up dack sections, disabled by the
power_down_unused_ram() API call.

Signed-off-by: Tomasz Chyrowicz <tomasz.chyrowicz@nordicsemi.no>

Author: tomchy

doc/nrf/libraries/others/ram_pwrdn.rst

@@ -11,6 +11,7 @@ The RAM power-down library is a basic module for disabling unused sections of RA
 
 To disable unused RAM sections, call :c:func:`power_down_unused_ram`.
 This function will automatically disable all memory regions that are not used by the application.
+To enable back unused RAM sections, call :c:func:`power_up_unused_ram`.
 
 .. note::
     :c:func:`power_down_unused_ram` powers down memory regions that are outside of the ``_image_ram_end`` boundary.

doc/nrf/releases/release-notes-changelog.rst

@@ -431,6 +431,10 @@ Bluetooth libraries and services
       * Serialization of the write callback applied to the GATT attribute.
       * Serialization of the :c:func:`bt_gatt_service_unregister` function call.
 
+  * :ref:`lib_ram_pwrdn`
+
+    * Added the :c:func:`power_up_unused_ram` API.
+
 Modem libraries
 ---------------
 

include/ram_pwrdn.h

@@ -48,6 +48,13 @@ void power_up_ram(uintptr_t start_address, uintptr_t end_address);
  */
 void power_down_unused_ram(void);
 
+/**
+ * @brief Request powering up unused RAM sections.
+ *
+ * Power up RAM sections which were disabled by @ref power_down_unused_ram function.
+ */
+void power_up_unused_ram(void);
+
 #ifdef __cplusplus
 }
 #endif

lib/ram_pwrdn/ram_pwrdn.c

@@ -197,6 +197,11 @@ void power_down_unused_ram(void)
 	power_down_ram(RAM_IMAGE_END_ADDR, ram_end_addr());
 }
 
+void power_up_unused_ram(void)
+{
+	power_up_ram(RAM_IMAGE_END_ADDR, ram_end_addr());
+}
+
 #if CONFIG_RAM_POWER_ADJUST_ON_HEAP_RESIZE
 
 static void libc_heap_resize_cb(uintptr_t heap_id, void *old_heap_end, void *new_heap_end)