u-boot/include/fdt_region.h
Heinrich Schuchardt 185f812c41 doc: replace @return by Return:
Sphinx expects Return: and not @return to indicate a return value.

find . -name '*.c' -exec \
sed -i 's/^\(\s\)\*\(\s*\)@return\(\s\)/\1*\2Return:\3/' {} \;

find . -name '*.h' -exec \
sed -i 's/^\(\s\)\*\(\s*\)@return\(\s\)/\1*\2Return:\3/' {} \;

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
2022-01-19 18:11:34 +01:00

305 lines
13 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _FDT_REGION_H
#define _FDT_REGION_H
#ifndef SWIG /* Not available in Python */
struct fdt_region {
int offset;
int size;
};
/*
* Flags for fdt_find_regions()
*
* Add a region for the string table (always the last region)
*/
#define FDT_REG_ADD_STRING_TAB (1 << 0)
/*
* Add all supernodes of a matching node/property, useful for creating a
* valid subset tree
*/
#define FDT_REG_SUPERNODES (1 << 1)
/* Add the FDT_BEGIN_NODE tags of subnodes, including their names */
#define FDT_REG_DIRECT_SUBNODES (1 << 2)
/* Add all subnodes of a matching node */
#define FDT_REG_ALL_SUBNODES (1 << 3)
/* Add a region for the mem_rsvmap table (always the first region) */
#define FDT_REG_ADD_MEM_RSVMAP (1 << 4)
/* Indicates what an fdt part is (node, property, value) */
#define FDT_IS_NODE (1 << 0)
#define FDT_IS_PROP (1 << 1)
#define FDT_IS_VALUE (1 << 2) /* not supported */
#define FDT_IS_COMPAT (1 << 3) /* used internally */
#define FDT_NODE_HAS_PROP (1 << 4) /* node contains prop */
#define FDT_ANY_GLOBAL (FDT_IS_NODE | FDT_IS_PROP | FDT_IS_VALUE | \
FDT_IS_COMPAT)
#define FDT_IS_ANY 0x1f /* all the above */
/* We set a reasonable limit on the number of nested nodes */
#define FDT_MAX_DEPTH 32
/* Decribes what we want to include from the current tag */
enum want_t {
WANT_NOTHING,
WANT_NODES_ONLY, /* No properties */
WANT_NODES_AND_PROPS, /* Everything for one level */
WANT_ALL_NODES_AND_PROPS /* Everything for all levels */
};
/* Keeps track of the state at parent nodes */
struct fdt_subnode_stack {
int offset; /* Offset of node */
enum want_t want; /* The 'want' value here */
int included; /* 1 if we included this node, 0 if not */
};
struct fdt_region_ptrs {
int depth; /* Current tree depth */
int done; /* What we have completed scanning */
enum want_t want; /* What we are currently including */
char *end; /* Pointer to end of full node path */
int nextoffset; /* Next node offset to check */
};
/* The state of our finding algortihm */
struct fdt_region_state {
struct fdt_subnode_stack stack[FDT_MAX_DEPTH]; /* node stack */
struct fdt_region *region; /* Contains list of regions found */
int count; /* Numnber of regions found */
const void *fdt; /* FDT blob */
int max_regions; /* Maximum regions to find */
int can_merge; /* 1 if we can merge with previous region */
int start; /* Start position of current region */
bool have_node; /* True if any node is included */
struct fdt_region_ptrs ptrs; /* Pointers for what we are up to */
};
/**
* fdt_find_regions() - find regions in device tree
*
* Given a list of nodes to include and properties to exclude, find
* the regions of the device tree which describe those included parts.
*
* The intent is to get a list of regions which will be invariant provided
* those parts are invariant. For example, if you request a list of regions
* for all nodes but exclude the property "data", then you will get the
* same region contents regardless of any change to "data" properties.
*
* This function can be used to produce a byte-stream to send to a hashing
* function to verify that critical parts of the FDT have not changed.
*
* Nodes which are given in 'inc' are included in the region list, as
* are the names of the immediate subnodes nodes (but not the properties
* or subnodes of those subnodes).
*
* For eaxample "/" means to include the root node, all root properties
* and the FDT_BEGIN_NODE and FDT_END_NODE of all subnodes of /. The latter
* ensures that we capture the names of the subnodes. In a hashing situation
* it prevents the root node from changing at all Any change to non-excluded
* properties, names of subnodes or number of subnodes would be detected.
*
* When used with FITs this provides the ability to hash and sign parts of
* the FIT based on different configurations in the FIT. Then it is
* impossible to change anything about that configuration (include images
* attached to the configuration), but it may be possible to add new
* configurations, new images or new signatures within the existing
* framework.
*
* Adding new properties to a device tree may result in the string table
* being extended (if the new property names are different from those
* already added). This function can optionally include a region for
* the string table so that this can be part of the hash too.
*
* The device tree header is not included in the list.
*
* @fdt: Device tree to check
* @inc: List of node paths to included
* @inc_count: Number of node paths in list
* @exc_prop: List of properties names to exclude
* @exc_prop_count: Number of properties in exclude list
* @region: Returns list of regions
* @max_region: Maximum length of region list
* @path: Pointer to a temporary string for the function to use for
* building path names
* @path_len: Length of path, must be large enough to hold the longest
* path in the tree
* @add_string_tab: 1 to add a region for the string table
* Return: number of regions in list. If this is >max_regions then the
* region array was exhausted. You should increase max_regions and try
* the call again.
*/
int fdt_find_regions(const void *fdt, char * const inc[], int inc_count,
char * const exc_prop[], int exc_prop_count,
struct fdt_region region[], int max_regions,
char *path, int path_len, int add_string_tab);
/**
* fdt_first_region() - find regions in device tree
*
* Given a nodes and properties to include and properties to exclude, find
* the regions of the device tree which describe those included parts.
*
* The use for this function is twofold. Firstly it provides a convenient
* way of performing a structure-aware grep of the tree. For example it is
* possible to grep for a node and get all the properties associated with
* that node. Trees can be subsetted easily, by specifying the nodes that
* are required, and then writing out the regions returned by this function.
* This is useful for small resource-constrained systems, such as boot
* loaders, which want to use an FDT but do not need to know about all of
* it.
*
* Secondly it makes it easy to hash parts of the tree and detect changes.
* The intent is to get a list of regions which will be invariant provided
* those parts are invariant. For example, if you request a list of regions
* for all nodes but exclude the property "data", then you will get the
* same region contents regardless of any change to "data" properties.
*
* This function can be used to produce a byte-stream to send to a hashing
* function to verify that critical parts of the FDT have not changed.
* Note that semantically null changes in order could still cause false
* hash misses. Such reordering might happen if the tree is regenerated
* from source, and nodes are reordered (the bytes-stream will be emitted
* in a different order and many hash functions will detect this). However
* if an existing tree is modified using libfdt functions, such as
* fdt_add_subnode() and fdt_setprop(), then this problem is avoided.
*
* The nodes/properties to include/exclude are defined by a function
* provided by the caller. This function is called for each node and
* property, and must return:
*
* 0 - to exclude this part
* 1 - to include this part
* -1 - for FDT_IS_PROP only: no information is available, so include
* if its containing node is included
*
* The last case is only used to deal with properties. Often a property is
* included if its containing node is included - this is the case where
* -1 is returned.. However if the property is specifically required to be
* included/excluded, then 0 or 1 can be returned. Note that including a
* property when the FDT_REG_SUPERNODES flag is given will force its
* containing node to be included since it is not valid to have a property
* that is not in a node.
*
* Using the information provided, the inclusion of a node can be controlled
* either by a node name or its compatible string, or any other property
* that the function can determine.
*
* As an example, including node "/" means to include the root node and all
* root properties. A flag provides a way of also including supernodes (of
* which there is none for the root node), and another flag includes
* immediate subnodes, so in this case we would get the FDT_BEGIN_NODE and
* FDT_END_NODE of all subnodes of /.
*
* The subnode feature helps in a hashing situation since it prevents the
* root node from changing at all. Any change to non-excluded properties,
* names of subnodes or number of subnodes would be detected.
*
* When used with FITs this provides the ability to hash and sign parts of
* the FIT based on different configurations in the FIT. Then it is
* impossible to change anything about that configuration (include images
* attached to the configuration), but it may be possible to add new
* configurations, new images or new signatures within the existing
* framework.
*
* Adding new properties to a device tree may result in the string table
* being extended (if the new property names are different from those
* already added). This function can optionally include a region for
* the string table so that this can be part of the hash too. This is always
* the last region.
*
* The FDT also has a mem_rsvmap table which can also be included, and is
* always the first region if so.
*
* The device tree header is not included in the region list. Since the
* contents of the FDT are changing (shrinking, often), the caller will need
* to regenerate the header anyway.
*
* @fdt: Device tree to check
* @h_include: Function to call to determine whether to include a part or
* not:
*
* @priv: Private pointer as passed to fdt_find_regions()
* @fdt: Pointer to FDT blob
* @offset: Offset of this node / property
* @type: Type of this part, FDT_IS_...
* @data: Pointer to data (node name, property name, compatible
* string, value (not yet supported)
* @size: Size of data, or 0 if none
* Return: 0 to exclude, 1 to include, -1 if no information is
* available
* @priv: Private pointer passed to h_include
* @region: Returns list of regions, sorted by offset
* @max_regions: Maximum length of region list
* @path: Pointer to a temporary string for the function to use for
* building path names
* @path_len: Length of path, must be large enough to hold the longest
* path in the tree
* @flags: Various flags that control the region algortihm, see
* FDT_REG_...
* Return: number of regions in list. If this is >max_regions then the
* region array was exhausted. You should increase max_regions and try
* the call again. Only the first max_regions elements are available in the
* array.
*
* On error a -ve value is return, which can be:
*
* -FDT_ERR_BADSTRUCTURE (too deep or more END tags than BEGIN tags
* -FDT_ERR_BADLAYOUT
* -FDT_ERR_NOSPACE (path area is too small)
*/
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);
/** fdt_next_region() - find next region
*
* See fdt_first_region() for full description. This function finds the
* next region according to the provided parameters, which must be the same
* as passed to fdt_first_region().
*
* This function can additionally return -FDT_ERR_NOTFOUND when there are no
* more regions
*/
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);
/**
* fdt_add_alias_regions() - find aliases that point to existing regions
*
* Once a device tree grep is complete some of the nodes will be present
* and some will have been dropped. This function checks all the alias nodes
* to figure out which points point to nodes which are still present. These
* aliases need to be kept, along with the nodes they reference.
*
* Given a list of regions function finds the aliases that still apply and
* adds more regions to the list for these. This function is called after
* fdt_next_region() has finished returning regions and requires the same
* state.
*
* @fdt: Device tree file to reference
* @region: List of regions that will be kept
* @count: Number of regions
* @max_regions: Number of entries that can fit in @region
* @info: Region state as returned from fdt_next_region()
* Return: new number of regions in @region (i.e. count + the number added)
* or -FDT_ERR_NOSPACE if there was not enough space.
*/
int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
int max_regions, struct fdt_region_state *info);
#endif /* SWIG */
#endif /* _FDT_REGION_H */