reserved-memory: Introduce support for reserved-memory node

Introduce a set of header files to be able to define and declare
sections and regions in the linker script. Introduce also DT helpers to
retrieve data back.

Signed-off-by: Carlo Caione <ccaione@baylibre.com>

dts/bindings/reserved-memory/reserved-memory.yaml

@@ -0,0 +1,23 @@
+description: |
+  Reserved memory - Each child of the reserved-memory node specifies one or
+  more regions of reserved memory. Regions in the /reserved-memory node may be
+  referenced by other device nodes by adding a memory-region property to the
+  device node.
+
+compatible: "reserved-memory"
+
+include:
+  - name: base.yaml
+    property-allowlist: ['#address-cells', '#size-cells']
+
+child-binding:
+    description: Regions
+    properties:
+       label:
+          type: string
+          required: false
+          description: Human readable string describing the device (used as device_get_binding() argument)
+       reg:
+          type: array
+          description: register space
+          required: true

include/devicetree/memory.h

@@ -0,0 +1,139 @@
+/**
+ * @file
+ * @brief reserved-memory Devicetree macro public API header file.
+ */
+
+/*
+ * Copyright (c) 2021 Carlo Caione <ccaione@baylibre.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_DEVICETREE_MEMORY_H_
+#define ZEPHYR_INCLUDE_DEVICETREE_MEMORY_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @defgroup devicetree-reserved Devicetree reserved-memory API
+ * @ingroup devicetree
+ * @{
+ */
+
+/**
+ * @brief Get the pointer to the reserved-memory region
+ *
+ * Example devicetree fragment:
+ *
+ *     reserved: reserved-memory {
+ *         compatible = "reserved-memory";
+ *         ...
+ *         n: node {
+ *             reg = <0x42000000 0x1000>;
+ *         };
+ *      };
+ *
+ * Example usage:
+ *
+ *     DT_RESERVED_MEM_GET_PTR(DT_NODELABEL(n)) // (uint8_t *) 0x42000000
+ *
+ * @param node_id node identifier
+ * @return pointer to the beginning of the reserved-memory region
+ */
+#define DT_RESERVED_MEM_GET_PTR(node_id) _DT_RESERVED_START(node_id)
+
+/**
+ * @brief Get the size of the reserved-memory region
+ *
+ * Example devicetree fragment:
+ *
+ *     reserved: reserved-memory {
+ *         compatible = "reserved-memory";
+ *         ...
+ *         n: node {
+ *             reg = <0x42000000 0x1000>;
+ *         };
+ *     };
+ *
+ * Example usage:
+ *
+ *     DT_RESERVED_MEM_GET_SIZE(DT_NODELABEL(n)) // 0x1000
+ *
+ * @param node_id node identifier
+ * @return the size of the reserved-memory region
+ */
+#define DT_RESERVED_MEM_GET_SIZE(node_id) DT_REG_SIZE(node_id)
+
+/**
+ * @brief Get the pointer to the reserved-memory region from a memory-reserved
+ *        phandle
+ *
+ * Example devicetree fragment:
+ *
+ *     reserved: reserved-memory {
+ *         compatible = "reserved-memory";
+ *         ...
+ *         res0: res {
+ *             reg = <0x42000000 0x1000>;
+ *             label = "res0";
+ *         };
+ *     };
+ *
+ *     n: node {
+ *         memory-region = <&res0>;
+ *     };
+ *
+ * Example usage:
+ *
+ *     DT_RESERVED_MEM_GET_PTR_BY_PHANDLE(DT_NODELABEL(n), memory_region) // (uint8_t *) 0x42000000
+ *
+ * @param node_id node identifier
+ * @param ph phandle to reserved-memory region
+ *
+ * @return pointer to the beginning of the reserved-memory region
+ */
+#define DT_RESERVED_MEM_GET_PTR_BY_PHANDLE(node_id, ph) \
+	DT_RESERVED_MEM_GET_PTR(DT_PHANDLE(node_id, ph))
+
+/**
+ * @brief Get the size of the reserved-memory region from a memory-reserved
+ *        phandle
+ *
+ * Example devicetree fragment:
+ *
+ *     reserved: reserved-memory {
+ *         compatible = "reserved-memory";
+ *         ...
+ *         res0: res {
+ *             reg = <0x42000000 0x1000>;
+ *             label = "res0";
+ *         };
+ *     };
+ *
+ *     n: node {
+ *         memory-region = <&res0>;
+ *     };
+ *
+ * Example usage:
+ *
+ *     DT_RESERVED_MEM_GET_SIZE_BY_PHANDLE(DT_NODELABEL(n), memory_region) // (uint8_t *) 0x42000000
+ *
+ * @param node_id node identifier
+ * @param ph phandle to reserved-memory region
+ *
+ * @return size of the reserved-memory region
+ */
+#define DT_RESERVED_MEM_GET_SIZE_BY_PHANDLE(node_id, ph) \
+	DT_RESERVED_MEM_GET_SIZE(DT_PHANDLE(node_id, ph))
+
+/**
+ * @}
+ */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  /* ZEPHYR_INCLUDE_DEVICETREE_MEMORY_H_ */

include/linker/devicetree_reserved.h

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2021, Carlo Caione <ccaione@baylibre.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Generate memory regions and sections from reserved-memory nodes.
+ */
+
+#include <devicetree.h>
+
+/* Reserved memory node */
+#define _NODE_RESERVED DT_INST(0, reserved_memory)
+
+/* Unquoted region label */
+#define _DT_LABEL_TOKEN(res) DT_STRING_TOKEN(res, label)
+
+/* _start and _end section symbols */
+#define _DT_RESERVED_PREFIX(res) UTIL_CAT(__, _DT_LABEL_TOKEN(res))
+#define _DT_RESERVED_START(res)  UTIL_CAT(_DT_RESERVED_PREFIX(res), _start)
+#define _DT_RESERVED_END(res)    UTIL_CAT(_DT_RESERVED_PREFIX(res), _end)
+
+/* Declare a reserved memory region */
+#define _RESERVED_REGION_DECLARE(res) DT_STRING_TOKEN(res, label) (rw) :	\
+				      ORIGIN = DT_REG_ADDR(res),		\
+				      LENGTH = DT_REG_SIZE(res)
+
+/* Declare a reserved memory section */
+#define _RESERVED_SECTION_DECLARE(res) SECTION_DATA_PROLOGUE(_DT_LABEL_TOKEN(res), ,)	\
+				       {						\
+					  _DT_RESERVED_START(res) = .;			\
+					  KEEP(*(._DT_LABEL_TOKEN(res)))		\
+					  KEEP(*(._DT_LABEL_TOKEN(res).*))		\
+					  _DT_RESERVED_END(res) =			\
+					  _DT_RESERVED_START(res) + DT_REG_SIZE(res);	\
+				       } GROUP_LINK_IN(_DT_LABEL_TOKEN(res))
+
+/* Declare reserved memory linker symbols */
+#define _RESERVED_SYMBOL_DECLARE(res) extern char _DT_RESERVED_START(res)[];	\
+				      extern char _DT_RESERVED_END(res)[];
+
+/* Apply a macro to a reserved memory region */
+#define _RESERVED_REGION_APPLY(f)						\
+	COND_CODE_1(IS_ENABLED(UTIL_CAT(_NODE_RESERVED, _EXISTS)),		\
+		    (DT_FOREACH_CHILD(_NODE_RESERVED, f)), ())
+
+/**
+ * @brief Generate region definitions for all the reserved memory regions
+ */
+#define DT_RESERVED_MEM_REGIONS() _RESERVED_REGION_APPLY(_RESERVED_REGION_DECLARE)
+
+/**
+ * @brief Generate section definitions for all the reserved memory regions
+ */
+#define DT_RESERVED_MEM_SECTIONS() _RESERVED_REGION_APPLY(_RESERVED_SECTION_DECLARE)
+
+/**
+ * @brief Generate linker script symbols for all the reserved memory regions
+ */
+#define DT_RESERVED_MEM_SYMBOLS() _RESERVED_REGION_APPLY(_RESERVED_SYMBOL_DECLARE)

include/linker/linker-defs.h

@@ -33,6 +33,7 @@
 #ifdef ZTEST_UNITTEST
 #define DT_NODE_HAS_STATUS(node, status) 0
 #else
+#include <linker/devicetree_reserved.h>
 #include <devicetree.h>
 #endif
 
@@ -213,6 +214,10 @@ extern char _image_rodata_size[];
 extern char _vector_start[];
 extern char _vector_end[];
 
+#if DT_NODE_HAS_STATUS(_NODE_RESERVED, okay)
+DT_RESERVED_MEM_SYMBOLS()
+#endif
+
 #ifdef CONFIG_SW_VECTOR_RELAY
 extern char __vector_relay_table[];
 #endif