linker: generate memory regions from devicetree partitions

boards/arm/nrf52832_mdk/nrf52832_mdk.dts

@@ -150,6 +150,7 @@
 		storage_partition: partition@7a000 {
 			label = "storage";
 			reg = <0x0007a000 0x00006000>;
+			linker-region;
 		};
 	};
 };

boards/arm/nrf52833dk_nrf52820/nrf52833dk_nrf52820.dts

@@ -148,6 +148,7 @@
 		storage_partition: partition@3a000 {
 			label = "storage";
 			reg = <0x0003a000 0x00006000>;
+			linker-region;
 		};
 	};
 };

boards/arm/nrf52833dk_nrf52833/nrf52833dk_nrf52833.dts

@@ -217,6 +217,7 @@ arduino_spi: &spi3 {
 		storage_partition: partition@7a000 {
 			label = "storage";
 			reg = <0x0007A000 0x00006000>;
+			linker-region;
 		};
 	};
 };

boards/arm/nrf52840_blip/nrf52840_blip.dts

@@ -166,6 +166,7 @@
 		storage_partition: partition@f8000 {
 			label = "storage";
 			reg = <0x000f8000 0x00008000>;
+			linker-region;
 		};
 	};
 };

boards/arm/nrf52840_mdk/nrf52840_mdk.dts

@@ -192,6 +192,7 @@
 		storage_partition: partition@f8000 {
 			label = "storage";
 			reg = <0x000f8000 0x00008000>;
+			linker-region;
 		};
 	};
 };

boards/arm/nrf52840_papyr/nrf52840_papyr.dts

@@ -164,6 +164,7 @@
 		storage_partition: partition@f8000 {
 			label = "storage";
 			reg = <0x000f8000 0x00008000>;
+			linker-region;
 		};
 	};
 };

boards/arm/nrf52840dk_nrf52811/nrf52840dk_nrf52811.dts

@@ -161,6 +161,7 @@
 		storage_partition: partition@29000 {
 			label = "storage";
 			reg = <0x00029000 0x00007000>;
+			linker-region;
 		};
 	};
 };

boards/arm/nrf52840dk_nrf52840/nrf52840dk_nrf52840.dts

@@ -274,6 +274,7 @@ arduino_spi: &spi3 {
 		storage_partition: partition@f8000 {
 			label = "storage";
 			reg = <0x000f8000 0x00008000>;
+			linker-region;
 		};
 	};
 };

dts/bindings/mtd/partition.yaml

@@ -24,6 +24,10 @@ child-binding:
           type: boolean
           required: false
           description: if the partition is read-only or not
+       linker-region:
+          type: boolean
+          required: false
+          description: generate a MEMORY region for this partition in the linker
        reg:
           type: array
           description: register space

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

@@ -13,6 +13,7 @@
 
 #include <autoconf.h>
 #include <linker/sections.h>
+#include <linker/devicetree_regions.h>
 #include <devicetree.h>
 
 #include <linker/linker-defs.h>
@@ -42,7 +43,8 @@
 #if CONFIG_FLASH_LOAD_SIZE > 0
   #define ROM_SIZE CONFIG_FLASH_LOAD_SIZE
 #else
-  #define ROM_SIZE (CONFIG_FLASH_SIZE*1K - CONFIG_FLASH_LOAD_OFFSET)
+  #define ROM_USABLE_END DT_PARTITION_REGIONS_START(CONFIG_FLASH_SIZE*1K)
+  #define ROM_SIZE (ROM_USABLE_END - CONFIG_FLASH_LOAD_OFFSET)
 #endif
 
 #if defined(CONFIG_XIP)
@@ -84,6 +86,8 @@ MEMORY
     SRAM     (wx) : ORIGIN = RAM_ADDR, LENGTH = RAM_SIZE
     /* Used by and documented in include/linker/intlist.ld */
     IDT_LIST (wx) : ORIGIN = (RAM_ADDR + RAM_SIZE), LENGTH = 2K
+    /* Add custom memory regions requested from devicetree */
+    DT_PARTITION_REGIONS()
 }
 
 ENTRY(CONFIG_KERNEL_ENTRY)

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

@@ -13,6 +13,7 @@
 
 #include <autoconf.h>
 #include <linker/sections.h>
+#include <linker/devicetree_regions.h>
 #include <devicetree.h>
 
 #include <linker/linker-defs.h>
@@ -48,7 +49,8 @@
 #if CONFIG_FLASH_LOAD_SIZE > 0
 #define ROM_SIZE CONFIG_FLASH_LOAD_SIZE
 #else
-#define ROM_SIZE (CONFIG_FLASH_SIZE*1K - CONFIG_FLASH_LOAD_OFFSET)
+#define ROM_USABLE_END DT_PARTITION_REGIONS_START(CONFIG_FLASH_SIZE*1K)
+#define ROM_SIZE (ROM_USABLE_END - CONFIG_FLASH_LOAD_OFFSET)
 #endif
 #endif
 
@@ -116,6 +118,8 @@ MEMORY
 #endif
     /* Used by and documented in include/linker/intlist.ld */
     IDT_LIST  (wx)      : ORIGIN = (RAM_ADDR + RAM_SIZE), LENGTH = 2K
+    /* Add custom memory regions requested from devicetree */
+    DT_PARTITION_REGIONS()
     }
 
 ENTRY(CONFIG_KERNEL_ENTRY)

include/linker/devicetree_regions.h

@@ -0,0 +1,47 @@
+/*
+ * Copyright (c) 2021, Commonwealth Scientific and Industrial Research
+ * Organisation (CSIRO) ABN 41 687 119 230.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Generate memory regions from devicetree partitions.
+ * Partitions are only considered if they exist under chosen/zephyr,flash.
+ */
+
+/* Partition under chosen/zephyr,flash */
+#define _CHOSEN_PARTITIONS UTIL_CAT(DT_CHOSEN(zephyr_flash), _S_partitions)
+
+/* Declare a memory region definition if `linker-region` is set */
+#define _REGION_DECLARE(part) COND_CODE_1(DT_PROP(part, linker_region),	\
+					  (DT_LABEL(part) (rx) :	\
+					   ORIGIN = DT_REG_ADDR(part),	\
+					   LENGTH = DT_REG_SIZE(part)),	\
+					  ())
+
+/* Return a memory region origin if `linker-region` is set*/
+#define _REGION_ADDR(part) COND_CODE_1(DT_PROP(part, linker_region), \
+				       (DT_REG_ADDR(part),),	     \
+				       ())
+
+/* Apply a macro to chosen partition, if it exists */
+#define _REGION_APPLY(f)					       \
+	COND_CODE_1(IS_ENABLED(UTIL_CAT(_CHOSEN_PARTITIONS, _EXISTS)), \
+		    (DT_FOREACH_CHILD(_CHOSEN_PARTITIONS, f)), ())
+
+/**
+ * @brief Find the lowest start address of all devicetree linker regions
+ *
+ * The MIN symbol passed to `FOR_EACH_NESTED` does not resolve to the standard
+ * ternery operation macro. Instead it is pasted as a symbol into the final
+ * linker file, where MIN is a builtin function in ld.
+ *     https://sourceware.org/binutils/docs/ld/Builtin-Functions.html
+ *
+ * @param def default return value if no custom partitions are present
+ */
+#define DT_PARTITION_REGIONS_START(def)	\
+	FOR_EACH_NESTED(MIN, def, _REGION_APPLY(_REGION_ADDR))
+
+/**
+ * @brief Generate region definitions for all devicetree linker regions
+ */
+#define DT_PARTITION_REGIONS() _REGION_APPLY(_REGION_DECLARE)

include/sys/util_internal.h

@@ -704,6 +704,43 @@
 #define Z_FOR_EACH_SWALLOW_INDEX_FIXED_ARG(F, fixed_arg, index, arg) F(arg)
 #define Z_FOR_EACH_SWALLOW_INDEX(F, fixed_arg, index, arg) F(arg, fixed_arg)
 
+/* Internal macros used by FOR_EACH_NESTED */
+#define _Z_FEN_1(F, term, ...)  F(GET_ARG_N(1, __VA_ARGS__), term)
+#define _Z_FEN_2(F, term, ...)  F(GET_ARG_N(2, __VA_ARGS__), \
+				  _Z_FEN_1(F, term, __VA_ARGS__))
+#define _Z_FEN_3(F, term, ...)  F(GET_ARG_N(3, __VA_ARGS__), \
+				  _Z_FEN_2(F, term, __VA_ARGS__))
+#define _Z_FEN_4(F, term, ...)  F(GET_ARG_N(4, __VA_ARGS__), \
+				  _Z_FEN_3(F, term, __VA_ARGS__))
+#define _Z_FEN_5(F, term, ...)  F(GET_ARG_N(5, __VA_ARGS__), \
+				  _Z_FEN_4(F, term, __VA_ARGS__))
+#define _Z_FEN_6(F, term, ...)  F(GET_ARG_N(6, __VA_ARGS__), \
+				  _Z_FEN_5(F, term, __VA_ARGS__))
+#define _Z_FEN_7(F, term, ...)  F(GET_ARG_N(7, __VA_ARGS__), \
+				  _Z_FEN_6(F, term, __VA_ARGS__))
+#define _Z_FEN_8(F, term, ...)  F(GET_ARG_N(8, __VA_ARGS__), \
+				  _Z_FEN_7(F, term, __VA_ARGS__))
+#define _Z_FEN_9(F, term, ...)  F(GET_ARG_N(9, __VA_ARGS__), \
+				  _Z_FEN_8(F, term, __VA_ARGS__))
+#define _Z_FEN_10(F, term, ...) F(GET_ARG_N(10, __VA_ARGS__), \
+				  _Z_FEN_9(F, term, __VA_ARGS__))
+#define _Z_FEN_11(F, term, ...) F(GET_ARG_N(11, __VA_ARGS__), \
+				  _Z_FEN_10(F, term, __VA_ARGS__))
+#define _Z_FEN_12(F, term, ...) F(GET_ARG_N(12, __VA_ARGS__), \
+				  _Z_FEN_11(F, term, __VA_ARGS__))
+#define _Z_FEN_13(F, term, ...) F(GET_ARG_N(13, __VA_ARGS__), \
+				  _Z_FEN_12(F, term, __VA_ARGS__))
+#define _Z_FEN_14(F, term, ...) F(GET_ARG_N(14, __VA_ARGS__), \
+				  _Z_FEN_13(F, term, __VA_ARGS__))
+#define _Z_FEN_15(F, term, ...) F(GET_ARG_N(15, __VA_ARGS__), \
+				  _Z_FEN_14(F, term, __VA_ARGS__))
+#define _Z_FEN_16(F, term, ...) F(GET_ARG_N(16, __VA_ARGS__), \
+				  _Z_FEN_15(F, term, __VA_ARGS__))
+
+#define _Z_FOR_EACH_NESTED(F, term, ...) \
+	UTIL_CAT(_Z_FEN_, NUM_VA_ARGS_LESS_1(__VA_ARGS__, _)) \
+	(F, term, __VA_ARGS__)
+
 /* This is a workaround to enable mixing GET_ARG_N with FOR_EACH macros. If
  * same UTIL_EVAL macro is used then macro is incorrectly resolved.
  */

include/sys/util_macro.h

@@ -526,6 +526,35 @@ extern "C" {
 			0, Z_FOR_EACH_SWALLOW_NOTHING, sep, \
 			F, fixed_arg, __VA_ARGS__)
 
+/**
+ * @brief Call a macro @p F on each provided argument in a nested fashion
+ *
+ * For each argument provided evaluates a two input macro where the second
+ * parameter is the result of the evaluation on the previous argument.
+ *
+ * Example:
+ *
+ *     // Find the smallest number in a list
+ *     FOR_EACH_NESTED(MIN, INT_MAX, 4, 5, 6);
+ *
+ * This expands to:
+ *
+ *     MIN(6, MIN(5, MIN(4, INT_MAX)))
+ *
+ * @param F Macro to invoke.
+ * @param term Final argument provided to the last invocation of @p F.
+ * @param ... Variable argument list.
+ * @return Result of macro invocation, or @p term if argument list is empty.
+ */
+#define FOR_EACH_NESTED(F, term, ...) \
+	COND_CODE_0(							\
+		/* are there zero non-empty arguments ? */		\
+		NUM_VA_ARGS_LESS_1(LIST_DROP_EMPTY(__VA_ARGS__, _)),	\
+		/* if so, expand to term */				\
+		(term),							\
+		/* otherwise, expand to: */				\
+		(_Z_FOR_EACH_NESTED(F, term, LIST_DROP_EMPTY(__VA_ARGS__))))
+
 /**
  * @brief Number of arguments in the variable arguments list minus one.
  *

samples/application_development/linker_regions/CMakeLists.txt

@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.13.1)
+
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(linker_regions)
+
+zephyr_linker_sources(SECTIONS partition_first.ld)
+zephyr_linker_sources_ifdef(SECOND_REGION SECTIONS partition_second.ld)
+
+target_sources(app PRIVATE src/main.c)

samples/application_development/linker_regions/README.rst

@@ -0,0 +1,23 @@
+.. _linker_regions:
+
+Linker Regions
+##############
+
+Overview
+********
+
+A sample that demonstrates using devicetree to define linker
+memory regions. These memory regions allow constants to be
+placed at desired memory addresses in a portable manner.
+
+Building and Running
+********************
+
+This application can be built and executed on QEMU as follows:
+
+.. zephyr-app-commands::
+   :zephyr-app: samples/application_development/linker_regions
+   :host-os: unix
+   :board: qemu_cortex_m3
+   :goals: run
+   :compact:

samples/application_development/linker_regions/boards/qemu_cortex_m3.overlay

@@ -0,0 +1,20 @@
+ /*
+  * Copyright (c) 2021, Commonwealth Scientific and Industrial Research
+  * Organisation (CSIRO) ABN 41 687 119 230.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&flash0 {
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		first_partition: partition@38000 {
+			label = "first_region";
+			reg = <0x00038000 0x00008000>;
+			linker-region;
+		};
+	};
+};

samples/application_development/linker_regions/boards/qemu_cortex_m3_multiple.overlay

@@ -0,0 +1,29 @@
+ /*
+  * Copyright (c) 2021, Commonwealth Scientific and Industrial Research
+  * Organisation (CSIRO) ABN 41 687 119 230.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&flash0 {
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		/* Regions are unordered to show the correct selection of
+		 * ROM bounds.
+		 */
+		first_partition: partition@3c000 {
+			label = "first_region";
+			reg = <0x0003c000 0x00004000>;
+			linker-region;
+		};
+
+		second_partition: partition@38000 {
+			label = "second_region";
+			reg = <0x00038000 0x00004000>;
+			linker-region;
+		};
+	};
+};

samples/application_development/linker_regions/partition_first.ld

@@ -0,0 +1,17 @@
+ /*
+  * Copyright (c) 2021, Commonwealth Scientific and Industrial Research
+  * Organisation (CSIRO) ABN 41 687 119 230.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/* Link ".first_section" into the first partition */
+GROUP_START(first_region)
+
+SECTION_DATA_PROLOGUE(first_section,,)
+{
+	KEEP(*(".first_section"));
+	KEEP(*(".first_section.*"));
+} GROUP_LINK_IN(first_region)
+
+GROUP_END(first_region)

samples/application_development/linker_regions/partition_second.ld

@@ -0,0 +1,17 @@
+ /*
+  * Copyright (c) 2021, Commonwealth Scientific and Industrial Research
+  * Organisation (CSIRO) ABN 41 687 119 230.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/* Link ".second_section" into the second partition */
+GROUP_START(second_region)
+
+SECTION_DATA_PROLOGUE(second_section,,)
+{
+	KEEP(*(".second_section"));
+	KEEP(*(".second_section.*"));
+} GROUP_LINK_IN(second_region)
+
+GROUP_END(second_region)

samples/application_development/linker_regions/prj.conf

@@ -0,0 +1 @@
+# nothing here