linker: arm: Add cortex_m itcm section

Adds a linker section for Cortex-M instruction tightly coupled memory
(ITCM), similar to the existing section for DTCM. A new executable MPU
region is not added as there isn't currently a need to make this section
accessible to user mode. This section can be enabled by setting a device
tree chosen node zephyr,itcm.

Signed-off-by: Maureen Helm <[email protected]>

Author: MaureenHelm

doc/reference/devicetree/api.rst

@@ -351,6 +351,8 @@ the source code to specify a device name.
      - A node whose ``reg`` is used by the OpenAMP subsystem to determine the
        base address and size of the shared memory (SHM) usable for
        interprocess-communication (IPC)
+   * - zephyr,itcm
+     - Instruction Tightly Coupled Memory node on some Arm SoCs
    * - zephyr,shell-uart
      - Sets default :option:`CONFIG_UART_SHELL_ON_DEV_NAME`
    * - zephyr,sram

include/arch/arm/aarch32/cortex_m/scripts/linker.ld

@@ -71,6 +71,11 @@
 #define CCM_ADDR DT_REG_ADDR(DT_CHOSEN(zephyr_ccm))
 #endif
 
+#if DT_NODE_HAS_STATUS(DT_CHOSEN(zephyr_itcm), okay)
+#define ITCM_SIZE DT_REG_SIZE(DT_CHOSEN(zephyr_itcm))
+#define ITCM_ADDR DT_REG_ADDR(DT_CHOSEN(zephyr_itcm))
+#endif
+
 #if DT_NODE_HAS_STATUS(DT_CHOSEN(zephyr_dtcm), okay)
 #define DTCM_SIZE DT_REG_SIZE(DT_CHOSEN(zephyr_dtcm))
 #define DTCM_ADDR DT_REG_ADDR(DT_CHOSEN(zephyr_dtcm))
@@ -108,6 +113,9 @@ MEMORY
 #if DT_NODE_HAS_STATUS(DT_CHOSEN(zephyr_ccm), okay)
     CCM                   (rw) : ORIGIN = CCM_ADDR, LENGTH = CCM_SIZE
 #endif
+#if DT_NODE_HAS_STATUS(DT_CHOSEN(zephyr_itcm), okay)
+    ITCM                  (rw) : ORIGIN = ITCM_ADDR, LENGTH = ITCM_SIZE
+#endif
 #if DT_NODE_HAS_STATUS(DT_CHOSEN(zephyr_dtcm), okay)
     DTCM                  (rw) : ORIGIN = DTCM_ADDR, LENGTH = DTCM_SIZE
 #endif
@@ -419,6 +427,23 @@ SECTIONS
 
     GROUP_END(RAMABLE_REGION)
 
+#if DT_NODE_HAS_STATUS(DT_CHOSEN(zephyr_itcm), okay)
+GROUP_START(ITCM)
+
+	SECTION_PROLOGUE(_ITCM_SECTION_NAME,,SUBALIGN(4))
+	{
+		__itcm_start = .;
+		*(.itcm)
+		*(".itcm.*")
+		__itcm_end = .;
+	} GROUP_LINK_IN(ITCM AT> ROMABLE_REGION)
+
+	__itcm_size = __itcm_end - __itcm_start;
+	__itcm_rom_start = LOADADDR(_ITCM_SECTION_NAME);
+
+GROUP_END(ITCM)
+#endif
+
 #if DT_NODE_HAS_STATUS(DT_CHOSEN(zephyr_dtcm), okay)
 GROUP_START(DTCM)
 

include/linker/linker-defs.h

@@ -230,6 +230,13 @@ extern char __ccm_noinit_end[];
 extern char __ccm_end[];
 #endif
 
+#if DT_NODE_HAS_STATUS(DT_CHOSEN(zephyr_itcm), okay)
+extern char __itcm_start[];
+extern char __itcm_end[];
+extern char __itcm_size[];
+extern char __itcm_rom_start[];
+#endif
+
 #if DT_NODE_HAS_STATUS(DT_CHOSEN(zephyr_dtcm), okay)
 extern char __dtcm_data_start[];
 extern char __dtcm_data_end[];

include/linker/section_tags.h

@@ -23,6 +23,7 @@
 #define __ccm_data_section Z_GENERIC_SECTION(_CCM_DATA_SECTION_NAME)
 #define __ccm_bss_section Z_GENERIC_SECTION(_CCM_BSS_SECTION_NAME)
 #define __ccm_noinit_section Z_GENERIC_SECTION(_CCM_NOINIT_SECTION_NAME)
+#define __itcm_section Z_GENERIC_SECTION(_ITCM_SECTION_NAME)
 #define __dtcm_data_section Z_GENERIC_SECTION(_DTCM_DATA_SECTION_NAME)
 #define __dtcm_bss_section Z_GENERIC_SECTION(_DTCM_BSS_SECTION_NAME)
 #define __dtcm_noinit_section Z_GENERIC_SECTION(_DTCM_NOINIT_SECTION_NAME)

include/linker/sections.h

@@ -43,6 +43,8 @@
 #define _CCM_BSS_SECTION_NAME		.ccm_bss
 #define _CCM_NOINIT_SECTION_NAME	.ccm_noinit
 
+#define _ITCM_SECTION_NAME		.itcm
+
 #define _DTCM_DATA_SECTION_NAME	.dtcm_data
 #define _DTCM_BSS_SECTION_NAME		.dtcm_bss
 #define _DTCM_NOINIT_SECTION_NAME	.dtcm_noinit

kernel/xip.c

@@ -35,6 +35,10 @@ void z_data_copy(void)
 	(void)memcpy(&__ccm_data_start, &__ccm_data_rom_start,
 		 __ccm_data_end - __ccm_data_start);
 #endif
+#if DT_NODE_HAS_STATUS(DT_CHOSEN(zephyr_itcm), okay)
+	(void)memcpy(&__itcm_start, &__itcm_rom_start,
+		 (uintptr_t) &__itcm_size);
+#endif
 #if DT_NODE_HAS_STATUS(DT_CHOSEN(zephyr_dtcm), okay)
 	(void)memcpy(&__dtcm_data_start, &__dtcm_data_rom_start,
 		 __dtcm_data_end - __dtcm_data_start);