fdt: Add fdt_first/next_region() functions

These have been sent upstream but not accepted to libfdt. For now, bring
these into U-Boot to enable fdtgrep to operate. We will use fdtgrep to
cut device tree files down for SPL.

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

2 files changed, 493 insertions, 1 deletions

diff --git a/lib/libfdt/Makefile b/lib/libfdt/Makefile
index 2f5413f90d6..934d6142c3e 100644
--- a/lib/libfdt/Makefile
+++ b/lib/libfdt/Makefile
@@ -6,4 +6,4 @@
 #
 
 obj-y += fdt.o fdt_ro.o fdt_rw.o fdt_strerror.o fdt_sw.o fdt_wip.o \
-	fdt_empty_tree.o fdt_addresses.o
+	fdt_empty_tree.o fdt_addresses.o fdt_region.o
diff --git a/lib/libfdt/fdt_region.c b/lib/libfdt/fdt_region.c
new file mode 100644
index 00000000000..9fea775a970
--- /dev/null
+++ b/lib/libfdt/fdt_region.c
@@ -0,0 +1,492 @@
+/*
+ * libfdt - Flat Device Tree manipulation
+ * Copyright (C) 2013 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ * SPDX-License-Identifier:	GPL-2.0+ BSD-2-Clause
+ */
+
+#include "libfdt_env.h"
+
+#ifndef USE_HOSTCC
+#include <fdt.h>
+#include <libfdt.h>
+#else
+#include "fdt_host.h"
+#endif
+
+#include "libfdt_internal.h"
+
+/**
+ * fdt_add_region() - Add a new region to our list
+ *
+ * The region is added if there is space, but in any case we increment the
+ * count. If permitted, and the new region overlaps the last one, we merge
+ * them.
+ *
+ * @info: State information
+ * @offset: Start offset of region
+ * @size: Size of region
+ */
+static int fdt_add_region(struct fdt_region_state *info, int offset, int size)
+{
+	struct fdt_region *reg;
+
+	reg = info->region ? &info->region[info->count - 1] : NULL;
+	if (info->can_merge && info->count &&
+	    info->count <= info->max_regions &&
+	    reg && offset <= reg->offset + reg->size) {
+		reg->size = offset + size - reg->offset;
+	} else if (info->count++ < info->max_regions) {
+		if (reg) {
+			reg++;
+			reg->offset = offset;
+			reg->size = size;
+		}
+	} else {
+		return -1;
+	}
+
+	return 0;
+}
+
+static int region_list_contains_offset(struct fdt_region_state *info,
+				       const void *fdt, int target)
+{
+	struct fdt_region *reg;
+	int num;
+
+	target += fdt_off_dt_struct(fdt);
+	for (reg = info->region, num = 0; num < info->count; reg++, num++) {
+		if (target >= reg->offset && target < reg->offset + reg->size)
+			return 1;
+	}
+
+	return 0;
+}
+
+int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
+			  int max_regions, struct fdt_region_state *info)
+{
+	int base = fdt_off_dt_struct(fdt);
+	int node, node_end, offset;
+	int did_alias_header;
+
+	node = fdt_subnode_offset(fdt, 0, "aliases");
+	if (node < 0)
+		return -FDT_ERR_NOTFOUND;
+
+	/* The aliases node must come before the others */
+	node_end = fdt_next_subnode(fdt, node);
+	if (node_end <= 0)
+		return -FDT_ERR_BADLAYOUT;
+	node_end -= sizeof(fdt32_t);
+
+	did_alias_header = 0;
+	info->region = region;
+	info->count = count;
+	info->can_merge = 0;
+	info->max_regions = max_regions;
+
+	for (offset = fdt_first_property_offset(fdt, node);
+	     offset >= 0;
+	     offset = fdt_next_property_offset(fdt, offset)) {
+		const struct fdt_property *prop;
+		const char *name;
+		int target, next;
+
+		prop = fdt_get_property_by_offset(fdt, offset, NULL);
+		name = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
+		target = fdt_path_offset(fdt, name);
+		if (!region_list_contains_offset(info, fdt, target))
+			continue;
+		next = fdt_next_property_offset(fdt, offset);
+		if (next < 0)
+			next = node_end - sizeof(fdt32_t);
+
+		if (!did_alias_header) {
+			fdt_add_region(info, base + node, 12);
+			did_alias_header = 1;
+		}
+		fdt_add_region(info, base + offset, next - offset);
+	}
+
+	/* Add the 'end' tag */
+	if (did_alias_header)
+		fdt_add_region(info, base + node_end, sizeof(fdt32_t));
+
+	return info->count < max_regions ? info->count : -FDT_ERR_NOSPACE;
+}
+
+/**
+ * fdt_include_supernodes() - Include supernodes required by this node
+ *
+ * When we decided to include a node or property which is not at the top
+ * level, this function forces the inclusion of higher level nodes. For
+ * example, given this tree:
+ *
+ * / {
+ *     testing {
+ *     }
+ * }
+ *
+ * If we decide to include testing then we need the root node to have a valid
+ * tree. This function adds those regions.
+ *
+ * @info: State information
+ * @depth: Current stack depth
+ */
+static int fdt_include_supernodes(struct fdt_region_state *info, int depth)
+{
+	int base = fdt_off_dt_struct(info->fdt);
+	int start, stop_at;
+	int i;
+
+	/*
+	 * Work down the stack looking for supernodes that we didn't include.
+	 * The algortihm here is actually pretty simple, since we know that
+	 * no previous subnode had to include these nodes, or if it did, we
+	 * marked them as included (on the stack) already.
+	 */
+	for (i = 0; i <= depth; i++) {
+		if (!info->stack[i].included) {
+			start = info->stack[i].offset;
+
+			/* Add the FDT_BEGIN_NODE tag of this supernode */
+			fdt_next_tag(info->fdt, start, &stop_at);
+			if (fdt_add_region(info, base + start, stop_at - start))
+				return -1;
+
+			/* Remember that this supernode is now included */
+			info->stack[i].included = 1;
+			info->can_merge = 1;
+		}
+
+		/* Force (later) generation of the FDT_END_NODE tag */
+		if (!info->stack[i].want)
+			info->stack[i].want = WANT_NODES_ONLY;
+	}
+
+	return 0;
+}
+
+enum {
+	FDT_DONE_NOTHING,
+	FDT_DONE_MEM_RSVMAP,
+	FDT_DONE_STRUCT,
+	FDT_DONE_END,
+	FDT_DONE_STRINGS,
+	FDT_DONE_ALL,
+};
+
+int fdt_first_region(const void *fdt,
+		int (*h_include)(void *priv, const void *fdt, int offset,
+				 int type, const char *data, int size),
+		void *priv, struct fdt_region *region,
+		char *path, int path_len, int flags,
+		struct fdt_region_state *info)
+{
+	struct fdt_region_ptrs *p = &info->ptrs;
+
+	/* Set up our state */
+	info->fdt = fdt;
+	info->can_merge = 1;
+	info->max_regions = 1;
+	info->start = -1;
+	p->want = WANT_NOTHING;
+	p->end = path;
+	*p->end = '\0';
+	p->nextoffset = 0;
+	p->depth = -1;
+	p->done = FDT_DONE_NOTHING;
+
+	return fdt_next_region(fdt, h_include, priv, region,
+			       path, path_len, flags, info);
+}
+
+/*
+ * Theory of operation
+ *
+ *
+ *
+
+Note: in this description 'included' means that a node (or other part of
+the tree) should be included in the region list, i.e. it will have a region
+which covers its part of the tree.
+
+This function maintains some state from the last time it is called. It
+checks the next part of the tree that it is supposed to look at
+(p.nextoffset) to see if that should be included or not. When it finds
+something to include, it sets info->start to its offset. This marks the
+start of the region we want to include.
+
+Once info->start is set to the start (i.e. not -1), we continue scanning
+until we find something that we don't want included. This will be the end
+of a region. At this point we can close off the region and add it to the
+list. So we do so, and reset info->start to -1.
+
+One complication here is that we want to merge regions. So when we come to
+add another region later, we may in fact merge it with the previous one if
+one ends where the other starts.
+
+The function fdt_add_region() will return -1 if it fails to add the region,
+because we already have a region ready to be returned, and the new one
+cannot be merged in with it. In this case, we must return the region we
+found, and wait for another call to this function. When it comes, we will
+repeat the processing of the tag and again try to add a region. This time it
+will succeed.
+
+The current state of the pointers (stack, offset, etc.) is maintained in
+a ptrs member. At the start of every loop iteration we make a copy of it.
+The copy is then updated as the tag is processed. Only if we get to the end
+of the loop iteration (and successfully call fdt_add_region() if we need
+to) can we commit the changes we have made to these pointers. For example,
+if we see an FDT_END_NODE tag we will decrement the depth value. But if we
+need to add a region for this tag (let's say because the previous tag is
+included and this FDT_END_NODE tag is not included) then we will only commit
+the result if we were able to add the region. That allows us to retry again
+next time.
+
+We keep track of a variable called 'want' which tells us what we want to
+include when there is no specific information provided by the h_include
+function for a particular property. This basically handles the inclusion of
+properties which are pulled in by virtue of the node they are in. So if you
+include a node, its properties are also included. In this case 'want' will
+be WANT_NODES_AND_PROPS. The FDT_REG_DIRECT_SUBNODES feature also makes use
+of 'want'. While we are inside the subnode, 'want' will be set to
+WANT_NODES_ONLY, so that only the subnode's FDT_BEGIN_NODE and FDT_END_NODE
+tags will be included, and properties will be skipped. If WANT_NOTHING is
+selected, then we will just rely on what the h_include() function tells us.
+
+Using 'want' we work out 'include', which tells us whether this current tag
+should be included or not. As you can imagine, if the value of 'include'
+changes, that means we are on a boundary between nodes to include and nodes
+to exclude. At this point we either close off a previous region and add it
+to the list, or mark the start of a new region.
+
+Apart from the nodes, we have mem_rsvmap, the FDT_END tag and the string
+list. Each of these dealt with as a whole (i.e. we create a region for each
+if it is to be included). For mem_rsvmap we don't allow it to merge with
+the first struct region. For the stringlist we don't allow it to merge with
+the last struct region (which contains at minimum the FDT_END tag).
+*/
+int fdt_next_region(const void *fdt,
+		int (*h_include)(void *priv, const void *fdt, int offset,
+				 int type, const char *data, int size),
+		void *priv, struct fdt_region *region,
+		char *path, int path_len, int flags,
+		struct fdt_region_state *info)
+{
+	int base = fdt_off_dt_struct(fdt);
+	int last_node = 0;
+	const char *str;
+
+	info->region = region;
+	info->count = 0;
+	if (info->ptrs.done < FDT_DONE_MEM_RSVMAP &&
+	    (flags & FDT_REG_ADD_MEM_RSVMAP)) {
+		/* Add the memory reserve map into its own region */
+		if (fdt_add_region(info, fdt_off_mem_rsvmap(fdt),
+				   fdt_off_dt_struct(fdt) -
+				   fdt_off_mem_rsvmap(fdt)))
+			return 0;
+		info->can_merge = 0;	/* Don't allow merging with this */
+		info->ptrs.done = FDT_DONE_MEM_RSVMAP;
+	}
+
+	/*
+	 * Work through the tags one by one, deciding whether each needs to
+	 * be included or not. We set the variable 'include' to indicate our
+	 * decision. 'want' is used to track what we want to include - it
+	 * allows us to pick up all the properties (and/or subnode tags) of
+	 * a node.
+	 */
+	while (info->ptrs.done < FDT_DONE_STRUCT) {
+		const struct fdt_property *prop;
+		struct fdt_region_ptrs p;
+		const char *name;
+		int include = 0;
+		int stop_at = 0;
+		uint32_t tag;
+		int offset;
+		int val;
+		int len;
+
+		/*
+		 * Make a copy of our pointers. If we make it to the end of
+		 * this block then we will commit them back to info->ptrs.
+		 * Otherwise we can try again from the same starting state
+		 * next time we are called.
+		 */
+		p = info->ptrs;
+
+		/*
+		 * Find the tag, and the offset of the next one. If we need to
+		 * stop including tags, then by default we stop *after*
+		 * including the current tag
+		 */
+		offset = p.nextoffset;
+		tag = fdt_next_tag(fdt, offset, &p.nextoffset);
+		stop_at = p.nextoffset;
+
+		switch (tag) {
+		case FDT_PROP:
+			stop_at = offset;
+			prop = fdt_get_property_by_offset(fdt, offset, NULL);
+			str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
+			val = h_include(priv, fdt, last_node, FDT_IS_PROP, str,
+					    strlen(str) + 1);
+			if (val == -1) {
+				include = p.want >= WANT_NODES_AND_PROPS;
+			} else {
+				include = val;
+				/*
+				 * Make sure we include the } for this block.
+				 * It might be more correct to have this done
+				 * by the call to fdt_include_supernodes() in
+				 * the case where it adds the node we are
+				 * currently in, but this is equivalent.
+				 */
+				if ((flags & FDT_REG_SUPERNODES) && val &&
+				    !p.want)
+					p.want = WANT_NODES_ONLY;
+			}
+
+			/* Value grepping is not yet supported */
+			break;
+
+		case FDT_NOP:
+			include = p.want >= WANT_NODES_AND_PROPS;
+			stop_at = offset;
+			break;
+
+		case FDT_BEGIN_NODE:
+			last_node = offset;
+			p.depth++;
+			if (p.depth == FDT_MAX_DEPTH)
+				return -FDT_ERR_TOODEEP;
+			name = fdt_get_name(fdt, offset, &len);
+			if (p.end - path + 2 + len >= path_len)
+				return -FDT_ERR_NOSPACE;
+
+			/* Build the full path of this node */
+			if (p.end != path + 1)
+				*p.end++ = '/';
+			strcpy(p.end, name);
+			p.end += len;
+			info->stack[p.depth].want = p.want;
+			info->stack[p.depth].offset = offset;
+
+			/*
+			 * If we are not intending to include this node unless
+			 * it matches, make sure we stop *before* its tag.
+			 */
+			if (p.want == WANT_NODES_ONLY ||
+			    !(flags & (FDT_REG_DIRECT_SUBNODES |
+				       FDT_REG_ALL_SUBNODES))) {
+				stop_at = offset;
+				p.want = WANT_NOTHING;
+			}
+			val = h_include(priv, fdt, offset, FDT_IS_NODE, path,
+					p.end - path + 1);
+
+			/* Include this if requested */
+			if (val) {
+				p.want = (flags & FDT_REG_ALL_SUBNODES) ?
+					WANT_ALL_NODES_AND_PROPS :
+					WANT_NODES_AND_PROPS;
+			}
+
+			/* If not requested, decay our 'p.want' value */
+			else if (p.want) {
+				if (p.want != WANT_ALL_NODES_AND_PROPS)
+					p.want--;
+
+			/* Not including this tag, so stop now */
+			} else {
+				stop_at = offset;
+			}
+
+			/*
+			 * Decide whether to include this tag, and update our
+			 * stack with the state for this node
+			 */
+			include = p.want;
+			info->stack[p.depth].included = include;
+			break;
+
+		case FDT_END_NODE:
+			include = p.want;
+			if (p.depth < 0)
+				return -FDT_ERR_BADSTRUCTURE;
+
+			/*
+			 * If we don't want this node, stop right away, unless
+			 * we are including subnodes
+			 */
+			if (!p.want && !(flags & FDT_REG_DIRECT_SUBNODES))
+				stop_at = offset;
+			p.want = info->stack[p.depth].want;
+			p.depth--;
+			while (p.end > path && *--p.end != '/')
+				;
+			*p.end = '\0';
+			break;
+
+		case FDT_END:
+			/* We always include the end tag */
+			include = 1;
+			p.done = FDT_DONE_STRUCT;
+			break;
+		}
+
+		/* If this tag is to be included, mark it as region start */
+		if (include && info->start == -1) {
+			/* Include any supernodes required by this one */
+			if (flags & FDT_REG_SUPERNODES) {
+				if (fdt_include_supernodes(info, p.depth))
+					return 0;
+			}
+			info->start = offset;
+		}
+
+		/*
+		 * If this tag is not to be included, finish up the current
+		 * region.
+		 */
+		if (!include && info->start != -1) {
+			if (fdt_add_region(info, base + info->start,
+					   stop_at - info->start))
+				return 0;
+			info->start = -1;
+			info->can_merge = 1;
+		}
+
+		/* If we have made it this far, we can commit our pointers */
+		info->ptrs = p;
+	}
+
+	/* Add a region for the END tag and a separate one for string table */
+	if (info->ptrs.done < FDT_DONE_END) {
+		if (info->ptrs.nextoffset != fdt_size_dt_struct(fdt))
+			return -FDT_ERR_BADSTRUCTURE;
+
+		if (fdt_add_region(info, base + info->start,
+				   info->ptrs.nextoffset - info->start))
+			return 0;
+		info->ptrs.done++;
+	}
+	if (info->ptrs.done < FDT_DONE_STRINGS) {
+		if (flags & FDT_REG_ADD_STRING_TAB) {
+			info->can_merge = 0;
+			if (fdt_off_dt_strings(fdt) <
+			    base + info->ptrs.nextoffset)
+				return -FDT_ERR_BADLAYOUT;
+			if (fdt_add_region(info, fdt_off_dt_strings(fdt),
+					   fdt_size_dt_strings(fdt)))
+				return 0;
+		}
+		info->ptrs.done++;
+	}
+
+	return info->count > 0 ? 0 : -FDT_ERR_NOTFOUND;
+}