1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _INCLUDE_LIBFDT_H_ 3 #define _INCLUDE_LIBFDT_H_ 4 5 #ifndef USE_HOSTCC 6 #include <linux/libfdt_env.h> 7 #endif 8 #include "../../scripts/dtc/libfdt/libfdt.h" 9 10 /* U-Boot local hacks */ 11 12 #ifndef SWIG /* Not available in Python */ 13 struct fdt_region { 14 int offset; 15 int size; 16 }; 17 18 /* 19 * Flags for fdt_find_regions() 20 * 21 * Add a region for the string table (always the last region) 22 */ 23 #define FDT_REG_ADD_STRING_TAB (1 << 0) 24 25 /* 26 * Add all supernodes of a matching node/property, useful for creating a 27 * valid subset tree 28 */ 29 #define FDT_REG_SUPERNODES (1 << 1) 30 31 /* Add the FDT_BEGIN_NODE tags of subnodes, including their names */ 32 #define FDT_REG_DIRECT_SUBNODES (1 << 2) 33 34 /* Add all subnodes of a matching node */ 35 #define FDT_REG_ALL_SUBNODES (1 << 3) 36 37 /* Add a region for the mem_rsvmap table (always the first region) */ 38 #define FDT_REG_ADD_MEM_RSVMAP (1 << 4) 39 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 */ 46 47 #define FDT_ANY_GLOBAL (FDT_IS_NODE | FDT_IS_PROP | FDT_IS_VALUE | \ 48 FDT_IS_COMPAT) 49 #define FDT_IS_ANY 0x1f /* all the above */ 50 51 /* We set a reasonable limit on the number of nested nodes */ 52 #define FDT_MAX_DEPTH 32 53 54 /* Decribes what we want to include from the current tag */ 55 enum want_t { 56 WANT_NOTHING, 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 */ 60 }; 61 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 */ 67 }; 68 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 */ 75 }; 76 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 */ 87 }; 88 89 /** 90 * fdt_find_regions() - find regions in device tree 91 * 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. 94 * 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. 99 * 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. 102 * 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). 106 * 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. 112 * 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 118 * framework. 119 * 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. 124 * 125 * The device tree header is not included in the list. 126 * 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 137 * path in the tree 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 141 * the call again. 142 */ 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); 147 148 /** 149 * fdt_first_region() - find regions in device tree 150 * 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. 153 * 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 161 * it. 162 * 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. 168 * 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. 177 * 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: 181 * 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 186 * 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. 194 * 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. 198 * 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 /. 204 * 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. 208 * 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 214 * framework. 215 * 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 220 * the last region. 221 * 222 * The FDT also has a mem_rsvmap table which can also be included, and is 223 * always the first region if so. 224 * 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. 228 * 229 * @fdt: Device tree to check 230 * @h_include: Function to call to determine whether to include a part or 231 * not: 232 * 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 241 * available 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 248 * path in the tree 249 * @flags: Various flags that control the region algortihm, see 250 * FDT_REG_... 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 254 * array. 255 * 256 * On error a -ve value is return, which can be: 257 * 258 * -FDT_ERR_BADSTRUCTURE (too deep or more END tags than BEGIN tags 259 * -FDT_ERR_BADLAYOUT 260 * -FDT_ERR_NOSPACE (path area is too small) 261 */ 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); 268 269 /** fdt_next_region() - find next region 270 * 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(). 274 * 275 * This function can additionally return -FDT_ERR_NOTFOUND when there are no 276 * more regions 277 */ 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); 284 285 /** 286 * fdt_add_alias_regions() - find aliases that point to existing regions 287 * 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. 292 * 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 296 * state. 297 * 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. 305 */ 306 int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count, 307 int max_regions, struct fdt_region_state *info); 308 #endif /* SWIG */ 309 310 extern struct fdt_header *working_fdt; /* Pointer to the working fdt */ 311 312 #endif /* _INCLUDE_LIBFDT_H_ */ 313