include/libfdt.h

   1 #ifndef UBOOT_LIBFDT_H
   2 #define UBOOT_LIBFDT_H
   3 /*
   4  * SPDX-License-Identifier:     GPL-2.0+ BSD-2-Clause
   5  */
   6
   7 #ifdef USE_HOSTCC
   8 #include "../scripts/dtc/libfdt/libfdt.h"
   9 #else
  10 #include <linux/libfdt.h>
  11 #endif
  12
  13 /* U-Boot local hacks */
  14
  15 #ifndef SWIG /* Not available in Python */
  16 struct fdt_region {
  17         int offset;
  18         int size;
  19 };
  20
  21 /*
  22  * Flags for fdt_find_regions()
  23  *
  24  * Add a region for the string table (always the last region)
  25  */
  26 #define FDT_REG_ADD_STRING_TAB          (1 << 0)
  27
  28 /*
  29  * Add all supernodes of a matching node/property, useful for creating a
  30  * valid subset tree
  31  */
  32 #define FDT_REG_SUPERNODES              (1 << 1)
  33
  34 /* Add the FDT_BEGIN_NODE tags of subnodes, including their names */
  35 #define FDT_REG_DIRECT_SUBNODES (1 << 2)
  36
  37 /* Add all subnodes of a matching node */
  38 #define FDT_REG_ALL_SUBNODES            (1 << 3)
  39
  40 /* Add a region for the mem_rsvmap table (always the first region) */
  41 #define FDT_REG_ADD_MEM_RSVMAP          (1 << 4)
  42
  43 /* Indicates what an fdt part is (node, property, value) */
  44 #define FDT_IS_NODE                     (1 << 0)
  45 #define FDT_IS_PROP                     (1 << 1)
  46 #define FDT_IS_VALUE                    (1 << 2)        /* not supported */
  47 #define FDT_IS_COMPAT                   (1 << 3)        /* used internally */
  48 #define FDT_NODE_HAS_PROP               (1 << 4)        /* node contains prop */
  49
  50 #define FDT_ANY_GLOBAL          (FDT_IS_NODE | FDT_IS_PROP | FDT_IS_VALUE | \
  51                                         FDT_IS_COMPAT)
  52 #define FDT_IS_ANY                      0x1f            /* all the above */
  53
  54 /* We set a reasonable limit on the number of nested nodes */
  55 #define FDT_MAX_DEPTH                   32
  56
  57 /* Decribes what we want to include from the current tag */
  58 enum want_t {
  59         WANT_NOTHING,
  60         WANT_NODES_ONLY,                /* No properties */
  61         WANT_NODES_AND_PROPS,           /* Everything for one level */
  62         WANT_ALL_NODES_AND_PROPS        /* Everything for all levels */
  63 };
  64
  65 /* Keeps track of the state at parent nodes */
  66 struct fdt_subnode_stack {
  67         int offset;             /* Offset of node */
  68         enum want_t want;       /* The 'want' value here */
  69         int included;           /* 1 if we included this node, 0 if not */
  70 };
  71
  72 struct fdt_region_ptrs {
  73         int depth;                      /* Current tree depth */
  74         int done;                       /* What we have completed scanning */
  75         enum want_t want;               /* What we are currently including */
  76         char *end;                      /* Pointer to end of full node path */
  77         int nextoffset;                 /* Next node offset to check */
  78 };
  79
  80 /* The state of our finding algortihm */
  81 struct fdt_region_state {
  82         struct fdt_subnode_stack stack[FDT_MAX_DEPTH];  /* node stack */
  83         struct fdt_region *region;      /* Contains list of regions found */
  84         int count;                      /* Numnber of regions found */
  85         const void *fdt;                /* FDT blob */
  86         int max_regions;                /* Maximum regions to find */
  87         int can_merge;          /* 1 if we can merge with previous region */
  88         int start;                      /* Start position of current region */
  89         struct fdt_region_ptrs ptrs;    /* Pointers for what we are up to */
  90 };
  91
  92 /**
  93  * fdt_find_regions() - find regions in device tree
  94  *
  95  * Given a list of nodes to include and properties to exclude, find
  96  * the regions of the device tree which describe those included parts.
  97  *
  98  * The intent is to get a list of regions which will be invariant provided
  99  * those parts are invariant. For example, if you request a list of regions
 100  * for all nodes but exclude the property "data", then you will get the
 101  * same region contents regardless of any change to "data" properties.
 102  *
 103  * This function can be used to produce a byte-stream to send to a hashing
 104  * function to verify that critical parts of the FDT have not changed.
 105  *
 106  * Nodes which are given in 'inc' are included in the region list, as
 107  * are the names of the immediate subnodes nodes (but not the properties
 108  * or subnodes of those subnodes).
 109  *
 110  * For eaxample "/" means to include the root node, all root properties
 111  * and the FDT_BEGIN_NODE and FDT_END_NODE of all subnodes of /. The latter
 112  * ensures that we capture the names of the subnodes. In a hashing situation
 113  * it prevents the root node from changing at all Any change to non-excluded
 114  * properties, names of subnodes or number of subnodes would be detected.
 115  *
 116  * When used with FITs this provides the ability to hash and sign parts of
 117  * the FIT based on different configurations in the FIT. Then it is
 118  * impossible to change anything about that configuration (include images
 119  * attached to the configuration), but it may be possible to add new
 120  * configurations, new images or new signatures within the existing
 121  * framework.
 122  *
 123  * Adding new properties to a device tree may result in the string table
 124  * being extended (if the new property names are different from those
 125  * already added). This function can optionally include a region for
 126  * the string table so that this can be part of the hash too.
 127  *
 128  * The device tree header is not included in the list.
 129  *
 130  * @fdt:        Device tree to check
 131  * @inc:        List of node paths to included
 132  * @inc_count:  Number of node paths in list
 133  * @exc_prop:   List of properties names to exclude
 134  * @exc_prop_count:     Number of properties in exclude list
 135  * @region:     Returns list of regions
 136  * @max_region: Maximum length of region list
 137  * @path:       Pointer to a temporary string for the function to use for
 138  *              building path names
 139  * @path_len:   Length of path, must be large enough to hold the longest
 140  *              path in the tree
 141  * @add_string_tab:     1 to add a region for the string table
 142  * @return number of regions in list. If this is >max_regions then the
 143  * region array was exhausted. You should increase max_regions and try
 144  * the call again.
 145  */
 146 int fdt_find_regions(const void *fdt, char * const inc[], int inc_count,
 147                      char * const exc_prop[], int exc_prop_count,
 148                      struct fdt_region region[], int max_regions,
 149                      char *path, int path_len, int add_string_tab);
 150
 151 /**
 152  * fdt_first_region() - find regions in device tree
 153  *
 154  * Given a nodes and properties to include and properties to exclude, find
 155  * the regions of the device tree which describe those included parts.
 156  *
 157  * The use for this function is twofold. Firstly it provides a convenient
 158  * way of performing a structure-aware grep of the tree. For example it is
 159  * possible to grep for a node and get all the properties associated with
 160  * that node. Trees can be subsetted easily, by specifying the nodes that
 161  * are required, and then writing out the regions returned by this function.
 162  * This is useful for small resource-constrained systems, such as boot
 163  * loaders, which want to use an FDT but do not need to know about all of
 164  * it.
 165  *
 166  * Secondly it makes it easy to hash parts of the tree and detect changes.
 167  * The intent is to get a list of regions which will be invariant provided
 168  * those parts are invariant. For example, if you request a list of regions
 169  * for all nodes but exclude the property "data", then you will get the
 170  * same region contents regardless of any change to "data" properties.
 171  *
 172  * This function can be used to produce a byte-stream to send to a hashing
 173  * function to verify that critical parts of the FDT have not changed.
 174  * Note that semantically null changes in order could still cause false
 175  * hash misses. Such reordering might happen if the tree is regenerated
 176  * from source, and nodes are reordered (the bytes-stream will be emitted
 177  * in a different order and many hash functions will detect this). However
 178  * if an existing tree is modified using libfdt functions, such as
 179  * fdt_add_subnode() and fdt_setprop(), then this problem is avoided.
 180  *
 181  * The nodes/properties to include/exclude are defined by a function
 182  * provided by the caller. This function is called for each node and
 183  * property, and must return:
 184  *
 185  *    0 - to exclude this part
 186  *    1 - to include this part
 187  *   -1 - for FDT_IS_PROP only: no information is available, so include
 188  *              if its containing node is included
 189  *
 190  * The last case is only used to deal with properties. Often a property is
 191  * included if its containing node is included - this is the case where
 192  * -1 is returned.. However if the property is specifically required to be
 193  * included/excluded, then 0 or 1 can be returned. Note that including a
 194  * property when the FDT_REG_SUPERNODES flag is given will force its
 195  * containing node to be included since it is not valid to have a property
 196  * that is not in a node.
 197  *
 198  * Using the information provided, the inclusion of a node can be controlled
 199  * either by a node name or its compatible string, or any other property
 200  * that the function can determine.
 201  *
 202  * As an example, including node "/" means to include the root node and all
 203  * root properties. A flag provides a way of also including supernodes (of
 204  * which there is none for the root node), and another flag includes
 205  * immediate subnodes, so in this case we would get the FDT_BEGIN_NODE and
 206  * FDT_END_NODE of all subnodes of /.
 207  *
 208  * The subnode feature helps in a hashing situation since it prevents the
 209  * root node from changing at all. Any change to non-excluded properties,
 210  * names of subnodes or number of subnodes would be detected.
 211  *
 212  * When used with FITs this provides the ability to hash and sign parts of
 213  * the FIT based on different configurations in the FIT. Then it is
 214  * impossible to change anything about that configuration (include images
 215  * attached to the configuration), but it may be possible to add new
 216  * configurations, new images or new signatures within the existing
 217  * framework.
 218  *
 219  * Adding new properties to a device tree may result in the string table
 220  * being extended (if the new property names are different from those
 221  * already added). This function can optionally include a region for
 222  * the string table so that this can be part of the hash too. This is always
 223  * the last region.
 224  *
 225  * The FDT also has a mem_rsvmap table which can also be included, and is
 226  * always the first region if so.
 227  *
 228  * The device tree header is not included in the region list. Since the
 229  * contents of the FDT are changing (shrinking, often), the caller will need
 230  * to regenerate the header anyway.
 231  *
 232  * @fdt:        Device tree to check
 233  * @h_include:  Function to call to determine whether to include a part or
 234  *              not:
 235  *
 236  *              @priv: Private pointer as passed to fdt_find_regions()
 237  *              @fdt: Pointer to FDT blob
 238  *              @offset: Offset of this node / property
 239  *              @type: Type of this part, FDT_IS_...
 240  *              @data: Pointer to data (node name, property name, compatible
 241  *                      string, value (not yet supported)
 242  *              @size: Size of data, or 0 if none
 243  *              @return 0 to exclude, 1 to include, -1 if no information is
 244  *              available
 245  * @priv:       Private pointer passed to h_include
 246  * @region:     Returns list of regions, sorted by offset
 247  * @max_regions: Maximum length of region list
 248  * @path:       Pointer to a temporary string for the function to use for
 249  *              building path names
 250  * @path_len:   Length of path, must be large enough to hold the longest
 251  *              path in the tree
 252  * @flags:      Various flags that control the region algortihm, see
 253  *              FDT_REG_...
 254  * @return number of regions in list. If this is >max_regions then the
 255  * region array was exhausted. You should increase max_regions and try
 256  * the call again. Only the first max_regions elements are available in the
 257  * array.
 258  *
 259  * On error a -ve value is return, which can be:
 260  *
 261  *      -FDT_ERR_BADSTRUCTURE (too deep or more END tags than BEGIN tags
 262  *      -FDT_ERR_BADLAYOUT
 263  *      -FDT_ERR_NOSPACE (path area is too small)
 264  */
 265 int fdt_first_region(const void *fdt,
 266                      int (*h_include)(void *priv, const void *fdt, int offset,
 267                                       int type, const char *data, int size),
 268                      void *priv, struct fdt_region *region,
 269                      char *path, int path_len, int flags,
 270                      struct fdt_region_state *info);
 271
 272 /** fdt_next_region() - find next region
 273  *
 274  * See fdt_first_region() for full description. This function finds the
 275  * next region according to the provided parameters, which must be the same
 276  * as passed to fdt_first_region().
 277  *
 278  * This function can additionally return -FDT_ERR_NOTFOUND when there are no
 279  * more regions
 280  */
 281 int fdt_next_region(const void *fdt,
 282                     int (*h_include)(void *priv, const void *fdt, int offset,
 283                                      int type, const char *data, int size),
 284                     void *priv, struct fdt_region *region,
 285                     char *path, int path_len, int flags,
 286                     struct fdt_region_state *info);
 287
 288 /**
 289  * fdt_add_alias_regions() - find aliases that point to existing regions
 290  *
 291  * Once a device tree grep is complete some of the nodes will be present
 292  * and some will have been dropped. This function checks all the alias nodes
 293  * to figure out which points point to nodes which are still present. These
 294  * aliases need to be kept, along with the nodes they reference.
 295  *
 296  * Given a list of regions function finds the aliases that still apply and
 297  * adds more regions to the list for these. This function is called after
 298  * fdt_next_region() has finished returning regions and requires the same
 299  * state.
 300  *
 301  * @fdt:        Device tree file to reference
 302  * @region:     List of regions that will be kept
 303  * @count:      Number of regions
 304  * @max_regions: Number of entries that can fit in @region
 305  * @info:       Region state as returned from fdt_next_region()
 306  * @return new number of regions in @region (i.e. count + the number added)
 307  * or -FDT_ERR_NOSPACE if there was not enough space.
 308  */
 309 int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
 310                           int max_regions, struct fdt_region_state *info);
 311 #endif /* SWIG */
 312
 313 extern struct fdt_header *working_fdt;  /* Pointer to the working fdt */
 314
 315 /* adding a ramdisk needs 0x44 bytes in version 2008.10 */
 316 #define FDT_RAMDISK_OVERHEAD    0x80
 317
 318 #endif /* UBOOT_LIBFDT_H */