dm: core: Add livetree definitions

Add a Kconfig option to enable a live device tree, built at run time from
the flat tree. Also add structure definitions and a root node.

Signed-off-by: Simon Glass <sjg@chromium.org>

dts/Kconfig

@@ -32,6 +32,17 @@ config SPL_OF_CONTROL
 	  which is not enough to support device tree. Enable this option to
 	  allow such boards to be supported by U-Boot SPL.
 
+config OF_LIVE
+	bool "Enable use of a live tree"
+	depends on OF_CONTROL
+	help
+	  Normally U-Boot uses a flat device tree which saves space and
+	  avoids the need to unpack the tree before use. However a flat
+	  tree does not support modifcation from within U-Boot since it
+	  can invalidate driver-model device tree offsets. This option
+	  enables a live tree which is available after relocation,
+	  and can be adjusted as needed.
+
 choice
 	prompt "Provider of DTB for DT control"
 	depends on OF_CONTROL

include/asm-generic/global_data.h

@@ -72,6 +72,9 @@ typedef struct global_data {
 	const void *fdt_blob;		/* Our device tree, NULL if none */
 	void *new_fdt;			/* Relocated FDT */
 	unsigned long fdt_size;		/* Space reserved for relocated FDT */
+#ifdef CONFIG_OF_LIVE
+	struct device_node *of_root;
+#endif
 	struct jt_funcs *jt;		/* jump table */
 	char env_buf[32];		/* buffer for getenv() before reloc. */
 #ifdef CONFIG_TRACE

include/dm/of.h

@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2017 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef _DM_OF_H
+#define _DM_OF_H
+
+#include <asm/u-boot.h>
+#include <asm/global_data.h>
+
+/* integer value within a device tree property which references another node */
+typedef u32 phandle;
+
+/**
+ * struct property: Device tree property
+ *
+ * @name: Property name
+ * @length: Length of property in bytes
+ * @value: Pointer to property value
+ * @next: Pointer to next property, or NULL if none
+ */
+struct property {
+	char *name;
+	int length;
+	void *value;
+	struct property *next;
+};
+
+/**
+ * struct device_node: Device tree node
+ *
+ * @name: Node name
+ * @type: Node type (value of device_type property) or "<NULL>" if none
+ * @phandle: Phandle value of this none, or 0 if none
+ * @full_name: Full path to node, e.g. "/bus@1/spi@1100"
+ * @properties: Pointer to head of list of properties, or NULL if none
+ * @parent: Pointer to parent node, or NULL if this is the root node
+ * @child: Pointer to head of child node list, or NULL if no children
+ * @sibling: Pointer to the next sibling node, or NULL if this is the last
+ */
+struct device_node {
+	const char *name;
+	const char *type;
+	phandle phandle;
+	const char *full_name;
+
+	struct property *properties;
+	struct device_node *parent;
+	struct device_node *child;
+	struct device_node *sibling;
+};
+
+#define OF_MAX_PHANDLE_ARGS 16
+
+/**
+ * struct of_phandle_args - structure to hold phandle and arguments
+ *
+ * This is used when decoding a phandle in a device tree property. Typically
+ * these look like this:
+ *
+ * wibble {
+ *    phandle = <5>;
+ * };
+ *
+ * ...
+ * some-prop = <&wibble 1 2 3>
+ *
+ * Here &node is the phandle of the node 'wibble', i.e. 5. There are three
+ * arguments: 1, 2, 3.
+ *
+ * So when decoding the phandle in some-prop, np will point to wibble,
+ * args_count will be 3 and the three arguments will be in args.
+ *
+ * @np: Node that the phandle refers to
+ * @args_count: Number of arguments
+ * @args: Argument values
+ */
+struct of_phandle_args {
+	struct device_node *np;
+	int args_count;
+	uint32_t args[OF_MAX_PHANDLE_ARGS];
+};
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/**
+ * of_live_active() - check if livetree is active
+ *
+ * @returns true if livetree is active, false it not
+ */
+#ifdef CONFIG_OF_LIVE
+static inline bool of_live_active(void)
+{
+	return gd->of_root != NULL;
+}
+#else
+static inline bool of_live_active(void)
+{
+	return false;
+}
+#endif
+
+#endif