boards: arm: nrf5340pdk: define sram0_image for image(s) RAM

We should not be using sram0 for image SRAM in nrf5340pdk.
sram0 represents the physical SRAM and that one includes the
shared memory between the two M33 CPUs on the SoC. We should
not be re-sizing sram0 to account for the shared RAM; instead
we would like to have sram0 representing the whole available
SRAM.

For that, we define a new memory node, sram0_image to
represent the 'image' SRAM that is available for Zephyr
on the board. sram0_image is the chosen image SRAM for
default builds, i.e. when TrustZone is ignored
(TRUSTED_EXECUTION_SECURE is not defined).

Signed-off-by: Ioannis Glaropoulos <[email protected]>

Author: ioannisg

boards/arm/nrf5340pdk_nrf5340/Kconfig.defconfig

@@ -26,8 +26,8 @@ config BOARD
 # If the secure firmware is to be combined with a non-secure image
 # (TRUSTED_EXECUTION_SECURE=y), the secure FW image SRAM shall always
 # be restricted to the secure image SRAM partition (sram-secure-partition).
-# Otherwise (if TRUSTED_EXECUTION_SECURE is not set) the whole sram0 may be
-# used by the image.
+# Otherwise (if TRUSTED_EXECUTION_SECURE is not set) the whole zephyr,sram
+# may be used by the image.
 #
 # For the non-secure version of the board, the firmware image SRAM is
 # always restricted to the allocated non-secure SRAM partition.

boards/arm/nrf5340pdk_nrf5340/nrf5340pdk_nrf5340_cpuapp.dts

@@ -10,7 +10,7 @@
 
 / {
 	chosen {
-		zephyr,sram = &sram0;
+		zephyr,sram = &sram0_image;
 		zephyr,flash = &flash0;
 		zephyr,code-partition = &slot0_partition;
 		zephyr,sram-secure-partition = &sram0_s;

boards/arm/nrf5340pdk_nrf5340/nrf5340pdk_nrf5340_cpuapp_common.dts

@@ -164,21 +164,23 @@
 	};
 };
 
-&sram0 {
+/ {
 
-	partitions {
-		compatible = "fixed-partitions";
+	reserved-memory {
 		#address-cells = <1>;
 		#size-cells = <1>;
+		ranges;
+
+		sram0_image: image@20000000 {
+			/* Zephyr image(s) memory */
+		};
 
-		/* SRAM allocated to the Secure image */
-		sram0_s: memory@20000000 {
-			label = "secure_sram_partition";
+		sram0_s: image_s@20000000 {
+			/* Secure image memory */
 		};
 
-		/* SRAM allocated to the Non-Secure image */
-		sram0_ns: memory@20010000 {
-			label = "non_secure_sram_partition";
+		sram0_ns: image_ns@20010000 {
+			/* Non-Secure image memory */
 		};
 	};
 };

boards/arm/nrf5340pdk_nrf5340/nrf5340pdk_nrf5340_cpuapp_partition_conf.dts

@@ -44,7 +44,7 @@
  * - Upper 64 kB SRAM allocated as Shared memory (sram0_shared)
  *   (see nrf5340pdk_nrf5340_shared_sram_planning_conf.dts)
  */
-&sram0 {
+&sram0_image {
 	reg = <0x20000000 DT_SIZE_K(448)>;
 };