1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _INCLUDE_LIBFDT_H_
3 #define _INCLUDE_LIBFDT_H_
6 #include <linux/libfdt_env.h>
8 #include "../../scripts/dtc/libfdt/libfdt.h"
10 /* U-Boot local hacks */
12 #ifndef SWIG /* Not available in Python */
19 * Flags for fdt_find_regions()
21 * Add a region for the string table (always the last region)
23 #define FDT_REG_ADD_STRING_TAB (1 << 0)
26 * Add all supernodes of a matching node/property, useful for creating a
29 #define FDT_REG_SUPERNODES (1 << 1)
31 /* Add the FDT_BEGIN_NODE tags of subnodes, including their names */
32 #define FDT_REG_DIRECT_SUBNODES (1 << 2)
34 /* Add all subnodes of a matching node */
35 #define FDT_REG_ALL_SUBNODES (1 << 3)
37 /* Add a region for the mem_rsvmap table (always the first region) */
38 #define FDT_REG_ADD_MEM_RSVMAP (1 << 4)
40 /* Indicates what an fdt part is (node, property, value) */
41 #define FDT_IS_NODE (1 << 0)
42 #define FDT_IS_PROP (1 << 1)
43 #define FDT_IS_VALUE (1 << 2) /* not supported */
44 #define FDT_IS_COMPAT (1 << 3) /* used internally */
45 #define FDT_NODE_HAS_PROP (1 << 4) /* node contains prop */
47 #define FDT_ANY_GLOBAL (FDT_IS_NODE | FDT_IS_PROP | FDT_IS_VALUE | \
49 #define FDT_IS_ANY 0x1f /* all the above */
51 /* We set a reasonable limit on the number of nested nodes */
52 #define FDT_MAX_DEPTH 32
54 /* Decribes what we want to include from the current tag */
57 WANT_NODES_ONLY, /* No properties */
58 WANT_NODES_AND_PROPS, /* Everything for one level */
59 WANT_ALL_NODES_AND_PROPS /* Everything for all levels */
62 /* Keeps track of the state at parent nodes */
63 struct fdt_subnode_stack {
64 int offset; /* Offset of node */
65 enum want_t want; /* The 'want' value here */
66 int included; /* 1 if we included this node, 0 if not */
69 struct fdt_region_ptrs {
70 int depth; /* Current tree depth */
71 int done; /* What we have completed scanning */
72 enum want_t want; /* What we are currently including */
73 char *end; /* Pointer to end of full node path */
74 int nextoffset; /* Next node offset to check */
77 /* The state of our finding algortihm */
78 struct fdt_region_state {
79 struct fdt_subnode_stack stack[FDT_MAX_DEPTH]; /* node stack */
80 struct fdt_region *region; /* Contains list of regions found */
81 int count; /* Numnber of regions found */
82 const void *fdt; /* FDT blob */
83 int max_regions; /* Maximum regions to find */
84 int can_merge; /* 1 if we can merge with previous region */
85 int start; /* Start position of current region */
86 struct fdt_region_ptrs ptrs; /* Pointers for what we are up to */
90 * fdt_find_regions() - find regions in device tree
92 * Given a list of nodes to include and properties to exclude, find
93 * the regions of the device tree which describe those included parts.
95 * The intent is to get a list of regions which will be invariant provided
96 * those parts are invariant. For example, if you request a list of regions
97 * for all nodes but exclude the property "data", then you will get the
98 * same region contents regardless of any change to "data" properties.
100 * This function can be used to produce a byte-stream to send to a hashing
101 * function to verify that critical parts of the FDT have not changed.
103 * Nodes which are given in 'inc' are included in the region list, as
104 * are the names of the immediate subnodes nodes (but not the properties
105 * or subnodes of those subnodes).
107 * For eaxample "/" means to include the root node, all root properties
108 * and the FDT_BEGIN_NODE and FDT_END_NODE of all subnodes of /. The latter
109 * ensures that we capture the names of the subnodes. In a hashing situation
110 * it prevents the root node from changing at all Any change to non-excluded
111 * properties, names of subnodes or number of subnodes would be detected.
113 * When used with FITs this provides the ability to hash and sign parts of
114 * the FIT based on different configurations in the FIT. Then it is
115 * impossible to change anything about that configuration (include images
116 * attached to the configuration), but it may be possible to add new
117 * configurations, new images or new signatures within the existing
120 * Adding new properties to a device tree may result in the string table
121 * being extended (if the new property names are different from those
122 * already added). This function can optionally include a region for
123 * the string table so that this can be part of the hash too.
125 * The device tree header is not included in the list.
127 * @fdt: Device tree to check
128 * @inc: List of node paths to included
129 * @inc_count: Number of node paths in list
130 * @exc_prop: List of properties names to exclude
131 * @exc_prop_count: Number of properties in exclude list
132 * @region: Returns list of regions
133 * @max_region: Maximum length of region list
134 * @path: Pointer to a temporary string for the function to use for
135 * building path names
136 * @path_len: Length of path, must be large enough to hold the longest
138 * @add_string_tab: 1 to add a region for the string table
139 * @return number of regions in list. If this is >max_regions then the
140 * region array was exhausted. You should increase max_regions and try
143 int fdt_find_regions(const void *fdt, char * const inc[], int inc_count,
144 char * const exc_prop[], int exc_prop_count,
145 struct fdt_region region[], int max_regions,
146 char *path, int path_len, int add_string_tab);
149 * fdt_first_region() - find regions in device tree
151 * Given a nodes and properties to include and properties to exclude, find
152 * the regions of the device tree which describe those included parts.
154 * The use for this function is twofold. Firstly it provides a convenient
155 * way of performing a structure-aware grep of the tree. For example it is
156 * possible to grep for a node and get all the properties associated with
157 * that node. Trees can be subsetted easily, by specifying the nodes that
158 * are required, and then writing out the regions returned by this function.
159 * This is useful for small resource-constrained systems, such as boot
160 * loaders, which want to use an FDT but do not need to know about all of
163 * Secondly it makes it easy to hash parts of the tree and detect changes.
164 * The intent is to get a list of regions which will be invariant provided
165 * those parts are invariant. For example, if you request a list of regions
166 * for all nodes but exclude the property "data", then you will get the
167 * same region contents regardless of any change to "data" properties.
169 * This function can be used to produce a byte-stream to send to a hashing
170 * function to verify that critical parts of the FDT have not changed.
171 * Note that semantically null changes in order could still cause false
172 * hash misses. Such reordering might happen if the tree is regenerated
173 * from source, and nodes are reordered (the bytes-stream will be emitted
174 * in a different order and many hash functions will detect this). However
175 * if an existing tree is modified using libfdt functions, such as
176 * fdt_add_subnode() and fdt_setprop(), then this problem is avoided.
178 * The nodes/properties to include/exclude are defined by a function
179 * provided by the caller. This function is called for each node and
180 * property, and must return:
182 * 0 - to exclude this part
183 * 1 - to include this part
184 * -1 - for FDT_IS_PROP only: no information is available, so include
185 * if its containing node is included
187 * The last case is only used to deal with properties. Often a property is
188 * included if its containing node is included - this is the case where
189 * -1 is returned.. However if the property is specifically required to be
190 * included/excluded, then 0 or 1 can be returned. Note that including a
191 * property when the FDT_REG_SUPERNODES flag is given will force its
192 * containing node to be included since it is not valid to have a property
193 * that is not in a node.
195 * Using the information provided, the inclusion of a node can be controlled
196 * either by a node name or its compatible string, or any other property
197 * that the function can determine.
199 * As an example, including node "/" means to include the root node and all
200 * root properties. A flag provides a way of also including supernodes (of
201 * which there is none for the root node), and another flag includes
202 * immediate subnodes, so in this case we would get the FDT_BEGIN_NODE and
203 * FDT_END_NODE of all subnodes of /.
205 * The subnode feature helps in a hashing situation since it prevents the
206 * root node from changing at all. Any change to non-excluded properties,
207 * names of subnodes or number of subnodes would be detected.
209 * When used with FITs this provides the ability to hash and sign parts of
210 * the FIT based on different configurations in the FIT. Then it is
211 * impossible to change anything about that configuration (include images
212 * attached to the configuration), but it may be possible to add new
213 * configurations, new images or new signatures within the existing
216 * Adding new properties to a device tree may result in the string table
217 * being extended (if the new property names are different from those
218 * already added). This function can optionally include a region for
219 * the string table so that this can be part of the hash too. This is always
222 * The FDT also has a mem_rsvmap table which can also be included, and is
223 * always the first region if so.
225 * The device tree header is not included in the region list. Since the
226 * contents of the FDT are changing (shrinking, often), the caller will need
227 * to regenerate the header anyway.
229 * @fdt: Device tree to check
230 * @h_include: Function to call to determine whether to include a part or
233 * @priv: Private pointer as passed to fdt_find_regions()
234 * @fdt: Pointer to FDT blob
235 * @offset: Offset of this node / property
236 * @type: Type of this part, FDT_IS_...
237 * @data: Pointer to data (node name, property name, compatible
238 * string, value (not yet supported)
239 * @size: Size of data, or 0 if none
240 * @return 0 to exclude, 1 to include, -1 if no information is
242 * @priv: Private pointer passed to h_include
243 * @region: Returns list of regions, sorted by offset
244 * @max_regions: Maximum length of region list
245 * @path: Pointer to a temporary string for the function to use for
246 * building path names
247 * @path_len: Length of path, must be large enough to hold the longest
249 * @flags: Various flags that control the region algortihm, see
251 * @return number of regions in list. If this is >max_regions then the
252 * region array was exhausted. You should increase max_regions and try
253 * the call again. Only the first max_regions elements are available in the
256 * On error a -ve value is return, which can be:
258 * -FDT_ERR_BADSTRUCTURE (too deep or more END tags than BEGIN tags
260 * -FDT_ERR_NOSPACE (path area is too small)
262 int fdt_first_region(const void *fdt,
263 int (*h_include)(void *priv, const void *fdt, int offset,
264 int type, const char *data, int size),
265 void *priv, struct fdt_region *region,
266 char *path, int path_len, int flags,
267 struct fdt_region_state *info);
269 /** fdt_next_region() - find next region
271 * See fdt_first_region() for full description. This function finds the
272 * next region according to the provided parameters, which must be the same
273 * as passed to fdt_first_region().
275 * This function can additionally return -FDT_ERR_NOTFOUND when there are no
278 int fdt_next_region(const void *fdt,
279 int (*h_include)(void *priv, const void *fdt, int offset,
280 int type, const char *data, int size),
281 void *priv, struct fdt_region *region,
282 char *path, int path_len, int flags,
283 struct fdt_region_state *info);
286 * fdt_add_alias_regions() - find aliases that point to existing regions
288 * Once a device tree grep is complete some of the nodes will be present
289 * and some will have been dropped. This function checks all the alias nodes
290 * to figure out which points point to nodes which are still present. These
291 * aliases need to be kept, along with the nodes they reference.
293 * Given a list of regions function finds the aliases that still apply and
294 * adds more regions to the list for these. This function is called after
295 * fdt_next_region() has finished returning regions and requires the same
298 * @fdt: Device tree file to reference
299 * @region: List of regions that will be kept
300 * @count: Number of regions
301 * @max_regions: Number of entries that can fit in @region
302 * @info: Region state as returned from fdt_next_region()
303 * @return new number of regions in @region (i.e. count + the number added)
304 * or -FDT_ERR_NOSPACE if there was not enough space.
306 int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
307 int max_regions, struct fdt_region_state *info);
310 extern struct fdt_header *working_fdt; /* Pointer to the working fdt */
312 #endif /* _INCLUDE_LIBFDT_H_ */