DeviceTree Kernel API

Core functions

struct device_node *of_find_all_nodes(struct device_node *prev)

Get next node in global list

Parameters

struct device_node *prev

Previous node or NULL to start iteration of_node_put() will be called on it

Return

A node pointer with refcount incremented, use of_node_put() on it when done.

int of_machine_is_compatible(const char *compat)

Test root of device tree for a given compatible value

Parameters

const char *compat

compatible string to look for in root node's compatible property.

Return

A positive integer if the root node has the given value in its compatible property.

bool of_device_is_available(const struct device_node *device)

check if a device is available for use

Parameters

const struct device_node *device

Node to check for availability

Return

True if the status property is absent or set to "okay" or "ok",

false otherwise

bool of_device_is_big_endian(const struct device_node *device)

check if a device has BE registers

Parameters

const struct device_node *device

Node to check for endianness

Return

True if the device has a "big-endian" property, or if the kernel

was compiled for BE and the device has a "native-endian" property. Returns false otherwise.

Callers would nominally use ioread32be/iowrite32be if of_device_is_big_endian() == true, or readl/writel otherwise.

struct device_node *of_get_parent(const struct device_node *node)

Get a node's parent if any

Parameters

const struct device_node *node

Node to get parent

Return

A node pointer with refcount incremented, use of_node_put() on it when done.

struct device_node *of_get_next_parent(struct device_node *node)

Iterate to a node's parent

Parameters

struct device_node *node

Node to get parent of

Description

This is like of_get_parent() except that it drops the refcount on the passed node, making it suitable for iterating through a node's parents.

Return

A node pointer with refcount incremented, use of_node_put() on it when done.

struct device_node *of_get_next_child(const struct device_node *node, struct device_node *prev)

Iterate a node childs

Parameters

const struct device_node *node

parent node

struct device_node *prev

previous child of the parent node, or NULL to get first

Return

A node pointer with refcount incremented, use of_node_put() on it when done. Returns NULL when prev is the last child. Decrements the refcount of prev.

struct device_node *of_get_next_available_child(const struct device_node *node, struct device_node *prev)

Find the next available child node

Parameters

const struct device_node *node

parent node

struct device_node *prev

previous child of the parent node, or NULL to get first

Description

This function is like of_get_next_child(), except that it automatically skips any disabled nodes (i.e. status = "disabled").

struct device_node *of_get_next_cpu_node(struct device_node *prev)

Iterate on cpu nodes

Parameters

struct device_node *prev

previous child of the /cpus node, or NULL to get first

Description

Unusable CPUs (those with the status property set to "fail" or "fail-...") will be skipped.

Return

A cpu node pointer with refcount incremented, use of_node_put() on it when done. Returns NULL when prev is the last child. Decrements the refcount of prev.

struct device_node *of_get_compatible_child(const struct device_node *parent, const char *compatible)

Find compatible child node

Parameters

const struct device_node *parent

parent node

const char *compatible

compatible string

Description

Lookup child node whose compatible property contains the given compatible string.

Return

a node pointer with refcount incremented, use of_node_put() on it when done; or NULL if not found.

struct device_node *of_get_child_by_name(const struct device_node *node, const char *name)

Find the child node by name for a given parent

Parameters

const struct device_node *node

parent node

const char *name

child name to look for.

Description

This function looks for child node for given matching name

Return

A node pointer if found, with refcount incremented, use of_node_put() on it when done. Returns NULL if node is not found.

struct device_node *of_find_node_opts_by_path(const char *path, const char **opts)

Find a node matching a full OF path

Parameters

const char *path

Either the full path to match, or if the path does not start with '/', the name of a property of the /aliases node (an alias). In the case of an alias, the node matching the alias' value will be returned.

const char **opts

Address of a pointer into which to store the start of an options string appended to the end of the path with a ':' separator.

Description

Valid paths:
  • /foo/bar Full path

  • foo Valid alias

  • foo/bar Valid alias + relative path

Return

A node pointer with refcount incremented, use of_node_put() on it when done.

struct device_node *of_find_node_by_name(struct device_node *from, const char *name)

Find a node by its "name" property

Parameters

struct device_node *from

The node to start searching from or NULL; the node you pass will not be searched, only the next one will. Typically, you pass what the previous call returned. of_node_put() will be called on from.

const char *name

The name string to match against

Return

A node pointer with refcount incremented, use of_node_put() on it when done.

struct device_node *of_find_node_by_type(struct device_node *from, const char *type)

Find a node by its "device_type" property

Parameters

struct device_node *from

The node to start searching from, or NULL to start searching the entire device tree. The node you pass will not be searched, only the next one will; typically, you pass what the previous call returned. of_node_put() will be called on from for you.

const char *type

The type string to match against

Return

A node pointer with refcount incremented, use of_node_put() on it when done.

struct device_node *of_find_compatible_node(struct device_node *from, const char *type, const char *compatible)

Find a node based on type and one of the tokens in its "compatible" property

Parameters

struct device_node *from

The node to start searching from or NULL, the node you pass will not be searched, only the next one will; typically, you pass what the previous call returned. of_node_put() will be called on it

const char *type

The type string to match "device_type" or NULL to ignore

const char *compatible

The string to match to one of the tokens in the device "compatible" list.

Return

A node pointer with refcount incremented, use of_node_put() on it when done.

struct device_node *of_find_node_with_property(struct device_node *from, const char *prop_name)

Find a node which has a property with the given name.

Parameters

struct device_node *from

The node to start searching from or NULL, the node you pass will not be searched, only the next one will; typically, you pass what the previous call returned. of_node_put() will be called on it

const char *prop_name

The name of the property to look for.

Return

A node pointer with refcount incremented, use of_node_put() on it when done.

const struct of_device_id *of_match_node(const struct of_device_id *matches, const struct device_node *node)

Tell if a device_node has a matching of_match structure

Parameters

const struct of_device_id *matches

array of of device match structures to search in

const struct device_node *node

the of device structure to match against

Description

Low level utility function used by device matching.

struct device_node *of_find_matching_node_and_match(struct device_node *from, const struct of_device_id *matches, const struct of_device_id **match)

Find a node based on an of_device_id match table.

Parameters

struct device_node *from

The node to start searching from or NULL, the node you pass will not be searched, only the next one will; typically, you pass what the previous call returned. of_node_put() will be called on it

const struct of_device_id *matches

array of of device match structures to search in

const struct of_device_id **match

Updated to point at the matches entry which matched

Return

A node pointer with refcount incremented, use of_node_put() on it when done.

int of_alias_from_compatible(const struct device_node *node, char *alias, int len)

Lookup appropriate alias for a device node depending on compatible

Parameters

const struct device_node *node

pointer to a device tree node

char *alias

Pointer to buffer that alias value will be copied into

int len

Length of alias value

Description

Based on the value of the compatible property, this routine will attempt to choose an appropriate alias value for a particular device tree node. It does this by stripping the manufacturer prefix (as delimited by a ',') from the first entry in the compatible list property.

Note

The matching on just the "product" side of the compatible is a relic from I2C and SPI. Please do not add any new user.

Return

This routine returns 0 on success, <0 on failure.

struct device_node *of_find_node_by_phandle(phandle handle)

Find a node given a phandle

Parameters

phandle handle

phandle of the node to find

Return

A node pointer with refcount incremented, use of_node_put() on it when done.

int of_parse_phandle_with_args_map(const struct device_node *np, const char *list_name, const char *stem_name, int index, struct of_phandle_args *out_args)

Find a node pointed by phandle in a list and remap it

Parameters

const struct device_node *np

pointer to a device tree node containing a list

const char *list_name

property name that contains a list

const char *stem_name

stem of property names that specify phandles' arguments count

int index

index of a phandle to parse out

struct of_phandle_args *out_args

optional pointer to output arguments structure (will be filled)

Description

This function is useful to parse lists of phandles and their arguments. Returns 0 on success and fills out_args, on error returns appropriate errno value. The difference between this function and of_parse_phandle_with_args() is that this API remaps a phandle if the node the phandle points to has a <stem_name>-map property.

Caller is responsible to call of_node_put() on the returned out_args->np pointer.

Example:

phandle1: node1 {
    #list-cells = <2>;
};

phandle2: node2 {
    #list-cells = <1>;
};

phandle3: node3 {
    #list-cells = <1>;
    list-map = <0 &phandle2 3>,
               <1 &phandle2 2>,
               <2 &phandle1 5 1>;
    list-map-mask = <0x3>;
};

node4 {
    list = <&phandle1 1 2 &phandle3 0>;
};

To get a device_node of the node2 node you may call this: of_parse_phandle_with_args(node4, "list", "list", 1, args);

int of_count_phandle_with_args(const struct device_node *np, const char *list_name, const char *cells_name)

Find the number of phandles references in a property

Parameters

const struct device_node *np

pointer to a device tree node containing a list

const char *list_name

property name that contains a list

const char *cells_name

property name that specifies phandles' arguments count

Return

The number of phandle + argument tuples within a property. It is a typical pattern to encode a list of phandle and variable arguments into a single property. The number of arguments is encoded by a property in the phandle-target node. For example, a gpios property would contain a list of GPIO specifies consisting of a phandle and 1 or more arguments. The number of arguments are determined by the #gpio-cells property in the node pointed to by the phandle.

int of_add_property(struct device_node *np, struct property *prop)

Add a property to a node

Parameters

struct device_node *np

Caller's Device Node

struct property *prop

Property to add

int of_remove_property(struct device_node *np, struct property *prop)

Remove a property from a node.

Parameters

struct device_node *np

Caller's Device Node

struct property *prop

Property to remove

Description

Note that we don't actually remove it, since we have given out who-knows-how-many pointers to the data using get-property. Instead we just move the property to the "dead properties" list, so it won't be found any more.

int of_alias_get_id(struct device_node *np, const char *stem)

Get alias id for the given device_node

Parameters

struct device_node *np

Pointer to the given device_node

const char *stem

Alias stem of the given device_node

Description

The function travels the lookup table to get the alias id for the given device_node and alias stem.

Return

The alias id if found.

int of_alias_get_highest_id(const char *stem)

Get highest alias id for the given stem

Parameters

const char *stem

Alias stem to be examined

Description

The function travels the lookup table to get the highest alias id for the given alias stem. It returns the alias id if found.

bool of_console_check(struct device_node *dn, char *name, int index)

Test and setup console for DT setup

Parameters

struct device_node *dn

Pointer to device node

char *name

Name to use for preferred console without index. ex. "ttyS"

int index

Index to use for preferred console.

Description

Check if the given device node matches the stdout-path property in the /chosen node. If it does then register it as the preferred console.

Return

TRUE if console successfully setup. Otherwise return FALSE.

int of_map_id(struct device_node *np, u32 id, const char *map_name, const char *map_mask_name, struct device_node **target, u32 *id_out)

Translate an ID through a downstream mapping.

Parameters

struct device_node *np

root complex device node.

u32 id

device ID to map.

const char *map_name

property name of the map to use.

const char *map_mask_name

optional property name of the mask to use.

struct device_node **target

optional pointer to a target device node.

u32 *id_out

optional pointer to receive the translated ID.

Description

Given a device ID, look up the appropriate implementation-defined platform ID and/or the target device which receives transactions on that ID, as per the "iommu-map" and "msi-map" bindings. Either of target or id_out may be NULL if only the other is required. If target points to a non-NULL device node pointer, only entries targeting that node will be matched; if it points to a NULL value, it will receive the device node of the first matching target phandle, with a reference held.

Return

0 on success or a standard error code on failure.

void of_node_init(struct device_node *node)

initialize a devicetree node

Parameters

struct device_node *node

Pointer to device node that has been created by kzalloc()

Description

On return the device_node refcount is set to one. Use of_node_put() on node when done to free the memory allocated for it. If the node is NOT a dynamic node the memory will not be freed. The decision of whether to free the memory will be done by node->release(), which is of_node_release().

struct device_node *of_parse_phandle(const struct device_node *np, const char *phandle_name, int index)

Resolve a phandle property to a device_node pointer

Parameters

const struct device_node *np

Pointer to device node holding phandle property

const char *phandle_name

Name of property holding a phandle value

int index

For properties holding a table of phandles, this is the index into the table

Return

The device_node pointer with refcount incremented. Use of_node_put() on it when done.

int of_parse_phandle_with_args(const struct device_node *np, const char *list_name, const char *cells_name, int index, struct of_phandle_args *out_args)

Find a node pointed by phandle in a list

Parameters

const struct device_node *np

pointer to a device tree node containing a list

const char *list_name

property name that contains a list

const char *cells_name

property name that specifies phandles' arguments count

int index

index of a phandle to parse out

struct of_phandle_args *out_args

optional pointer to output arguments structure (will be filled)

Description

This function is useful to parse lists of phandles and their arguments. Returns 0 on success and fills out_args, on error returns appropriate errno value.

Caller is responsible to call of_node_put() on the returned out_args->np pointer.

Example:

phandle1: node1 {
    #list-cells = <2>;
};

phandle2: node2 {
    #list-cells = <1>;
};

node3 {
    list = <&phandle1 1 2 &phandle2 3>;
};

To get a device_node of the node2 node you may call this: of_parse_phandle_with_args(node3, "list", "#list-cells", 1, args);

int of_parse_phandle_with_fixed_args(const struct device_node *np, const char *list_name, int cell_count, int index, struct of_phandle_args *out_args)

Find a node pointed by phandle in a list

Parameters

const struct device_node *np

pointer to a device tree node containing a list

const char *list_name

property name that contains a list

int cell_count

number of argument cells following the phandle

int index

index of a phandle to parse out

struct of_phandle_args *out_args

optional pointer to output arguments structure (will be filled)

Description

This function is useful to parse lists of phandles and their arguments. Returns 0 on success and fills out_args, on error returns appropriate errno value.

Caller is responsible to call of_node_put() on the returned out_args->np pointer.

Example:

phandle1: node1 {
};

phandle2: node2 {
};

node3 {
    list = <&phandle1 0 2 &phandle2 2 3>;
};

To get a device_node of the node2 node you may call this: of_parse_phandle_with_fixed_args(node3, "list", 2, 1, args);

int of_parse_phandle_with_optional_args(const struct device_node *np, const char *list_name, const char *cells_name, int index, struct of_phandle_args *out_args)

Find a node pointed by phandle in a list

Parameters

const struct device_node *np

pointer to a device tree node containing a list

const char *list_name

property name that contains a list

const char *cells_name

property name that specifies phandles' arguments count

int index

index of a phandle to parse out

struct of_phandle_args *out_args

optional pointer to output arguments structure (will be filled)

Description

Same as of_parse_phandle_with_args() except that if the cells_name property is not found, cell_count of 0 is assumed.

This is used to useful, if you have a phandle which didn't have arguments before and thus doesn't have a '#*-cells' property but is now migrated to having arguments while retaining backwards compatibility.

int of_property_count_u8_elems(const struct device_node *np, const char *propname)

Count the number of u8 elements in a property

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

Description

Search for a property in a device node and count the number of u8 elements in it.

Return

The number of elements on sucess, -EINVAL if the property does not exist or its length does not match a multiple of u8 and -ENODATA if the property does not have a value.

int of_property_count_u16_elems(const struct device_node *np, const char *propname)

Count the number of u16 elements in a property

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

Description

Search for a property in a device node and count the number of u16 elements in it.

Return

The number of elements on sucess, -EINVAL if the property does not exist or its length does not match a multiple of u16 and -ENODATA if the property does not have a value.

int of_property_count_u32_elems(const struct device_node *np, const char *propname)

Count the number of u32 elements in a property

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

Description

Search for a property in a device node and count the number of u32 elements in it.

Return

The number of elements on sucess, -EINVAL if the property does not exist or its length does not match a multiple of u32 and -ENODATA if the property does not have a value.

int of_property_count_u64_elems(const struct device_node *np, const char *propname)

Count the number of u64 elements in a property

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

Description

Search for a property in a device node and count the number of u64 elements in it.

Return

The number of elements on sucess, -EINVAL if the property does not exist or its length does not match a multiple of u64 and -ENODATA if the property does not have a value.

int of_property_read_string_array(const struct device_node *np, const char *propname, const char **out_strs, size_t sz)

Read an array of strings from a multiple strings property.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

const char **out_strs

output array of string pointers.

size_t sz

number of array elements to read.

Description

Search for a property in a device tree node and retrieve a list of terminated string values (pointer to data, not a copy) in that property.

Return

If out_strs is NULL, the number of strings in the property is returned.

int of_property_count_strings(const struct device_node *np, const char *propname)

Find and return the number of strings from a multiple strings property.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

Description

Search for a property in a device tree node and retrieve the number of null terminated string contain in it.

Return

The number of strings on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EILSEQ if the string is not null-terminated within the length of the property data.

int of_property_read_string_index(const struct device_node *np, const char *propname, int index, const char **output)

Find and read a string from a multiple strings property.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

int index

index of the string in the list of strings

const char **output

pointer to null terminated return string, modified only if return value is 0.

Description

Search for a property in a device tree node and retrieve a null terminated string value (pointer to data, not a copy) in the list of strings contained in that property.

The out_string pointer is modified only if a valid string can be decoded.

Return

0 on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EILSEQ if the string is not null-terminated within the length of the property data.

bool of_property_read_bool(const struct device_node *np, const char *propname)

Find a property

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

Description

Search for a boolean property in a device node. Usage on non-boolean property types is deprecated.

Return

true if the property exists false otherwise.

bool of_property_present(const struct device_node *np, const char *propname)

Test if a property is present in a node

Parameters

const struct device_node *np

device node to search for the property.

const char *propname

name of the property to be searched.

Description

Test for a property present in a device node.

Return

true if the property exists false otherwise.

int of_property_read_u8_array(const struct device_node *np, const char *propname, u8 *out_values, size_t sz)

Find and read an array of u8 from a property.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

u8 *out_values

pointer to return value, modified only if return value is 0.

size_t sz

number of array elements to read

Description

Search for a property in a device node and read 8-bit value(s) from it.

dts entry of array should be like:

property = /bits/ 8 <0x50 0x60 0x70>;

The out_values is modified only if a valid u8 value can be decoded.

Return

0 on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EOVERFLOW if the property data isn't large enough.

int of_property_read_u16_array(const struct device_node *np, const char *propname, u16 *out_values, size_t sz)

Find and read an array of u16 from a property.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

u16 *out_values

pointer to return value, modified only if return value is 0.

size_t sz

number of array elements to read

Description

Search for a property in a device node and read 16-bit value(s) from it.

dts entry of array should be like:

property = /bits/ 16 <0x5000 0x6000 0x7000>;

The out_values is modified only if a valid u16 value can be decoded.

Return

0 on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EOVERFLOW if the property data isn't large enough.

int of_property_read_u32_array(const struct device_node *np, const char *propname, u32 *out_values, size_t sz)

Find and read an array of 32 bit integers from a property.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

u32 *out_values

pointer to return value, modified only if return value is 0.

size_t sz

number of array elements to read

Description

Search for a property in a device node and read 32-bit value(s) from it.

The out_values is modified only if a valid u32 value can be decoded.

Return

0 on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EOVERFLOW if the property data isn't large enough.

int of_property_read_u64_array(const struct device_node *np, const char *propname, u64 *out_values, size_t sz)

Find and read an array of 64 bit integers from a property.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

u64 *out_values

pointer to return value, modified only if return value is 0.

size_t sz

number of array elements to read

Description

Search for a property in a device node and read 64-bit value(s) from it.

The out_values is modified only if a valid u64 value can be decoded.

Return

0 on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EOVERFLOW if the property data isn't large enough.

struct of_changeset_entry

Holds a changeset entry

Definition:

struct of_changeset_entry {
    struct list_head node;
    unsigned long action;
    struct device_node *np;
    struct property *prop;
    struct property *old_prop;
};

Members

node

list_head for the log list

action

notifier action

np

pointer to the device node affected

prop

pointer to the property affected

old_prop

hold a pointer to the original property

Description

Every modification of the device tree during a changeset is held in a list of of_changeset_entry structures. That way we can recover from a partial application, or we can revert the changeset

struct of_changeset

changeset tracker structure

Definition:

struct of_changeset {
    struct list_head entries;
};

Members

entries

list_head for the changeset entries

Description

changesets are a convenient way to apply bulk changes to the live tree. In case of an error, changes are rolled-back. changesets live on after initial application, and if not destroyed after use, they can be reverted in one single call.

bool of_device_is_system_power_controller(const struct device_node *np)

Tells if system-power-controller is found for device_node

Parameters

const struct device_node *np

Pointer to the given device_node

Return

true if present false otherwise

bool of_graph_is_present(const struct device_node *node)

check graph's presence

Parameters

const struct device_node *node

pointer to device_node containing graph port

Return

True if node has a port or ports (with a port) sub-node, false otherwise.

int of_property_count_elems_of_size(const struct device_node *np, const char *propname, int elem_size)

Count the number of elements in a property

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

int elem_size

size of the individual element

Description

Search for a property in a device node and count the number of elements of size elem_size in it.

Return

The number of elements on sucess, -EINVAL if the property does not exist or its length does not match a multiple of elem_size and -ENODATA if the property does not have a value.

int of_property_read_u32_index(const struct device_node *np, const char *propname, u32 index, u32 *out_value)

Find and read a u32 from a multi-value property.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

u32 index

index of the u32 in the list of values

u32 *out_value

pointer to return value, modified only if no error.

Description

Search for a property in a device node and read nth 32-bit value from it.

The out_value is modified only if a valid u32 value can be decoded.

Return

0 on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EOVERFLOW if the property data isn't large enough.

int of_property_read_u64_index(const struct device_node *np, const char *propname, u32 index, u64 *out_value)

Find and read a u64 from a multi-value property.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

u32 index

index of the u64 in the list of values

u64 *out_value

pointer to return value, modified only if no error.

Description

Search for a property in a device node and read nth 64-bit value from it.

The out_value is modified only if a valid u64 value can be decoded.

Return

0 on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EOVERFLOW if the property data isn't large enough.

int of_property_read_variable_u8_array(const struct device_node *np, const char *propname, u8 *out_values, size_t sz_min, size_t sz_max)

Find and read an array of u8 from a property, with bounds on the minimum and maximum array size.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

u8 *out_values

pointer to found values.

size_t sz_min

minimum number of array elements to read

size_t sz_max

maximum number of array elements to read, if zero there is no upper limit on the number of elements in the dts entry but only sz_min will be read.

Description

Search for a property in a device node and read 8-bit value(s) from it.

dts entry of array should be like:

property = /bits/ 8 <0x50 0x60 0x70>;

The out_values is modified only if a valid u8 value can be decoded.

Return

The number of elements read on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EOVERFLOW if the property data is smaller than sz_min or longer than sz_max.

int of_property_read_variable_u16_array(const struct device_node *np, const char *propname, u16 *out_values, size_t sz_min, size_t sz_max)

Find and read an array of u16 from a property, with bounds on the minimum and maximum array size.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

u16 *out_values

pointer to found values.

size_t sz_min

minimum number of array elements to read

size_t sz_max

maximum number of array elements to read, if zero there is no upper limit on the number of elements in the dts entry but only sz_min will be read.

Description

Search for a property in a device node and read 16-bit value(s) from it.

dts entry of array should be like:

property = /bits/ 16 <0x5000 0x6000 0x7000>;

The out_values is modified only if a valid u16 value can be decoded.

Return

The number of elements read on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EOVERFLOW if the property data is smaller than sz_min or longer than sz_max.

int of_property_read_variable_u32_array(const struct device_node *np, const char *propname, u32 *out_values, size_t sz_min, size_t sz_max)

Find and read an array of 32 bit integers from a property, with bounds on the minimum and maximum array size.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

u32 *out_values

pointer to return found values.

size_t sz_min

minimum number of array elements to read

size_t sz_max

maximum number of array elements to read, if zero there is no upper limit on the number of elements in the dts entry but only sz_min will be read.

Description

Search for a property in a device node and read 32-bit value(s) from it.

The out_values is modified only if a valid u32 value can be decoded.

Return

The number of elements read on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EOVERFLOW if the property data is smaller than sz_min or longer than sz_max.

int of_property_read_u64(const struct device_node *np, const char *propname, u64 *out_value)

Find and read a 64 bit integer from a property

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

u64 *out_value

pointer to return value, modified only if return value is 0.

Description

Search for a property in a device node and read a 64-bit value from it.

The out_value is modified only if a valid u64 value can be decoded.

Return

0 on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EOVERFLOW if the property data isn't large enough.

int of_property_read_variable_u64_array(const struct device_node *np, const char *propname, u64 *out_values, size_t sz_min, size_t sz_max)

Find and read an array of 64 bit integers from a property, with bounds on the minimum and maximum array size.

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

u64 *out_values

pointer to found values.

size_t sz_min

minimum number of array elements to read

size_t sz_max

maximum number of array elements to read, if zero there is no upper limit on the number of elements in the dts entry but only sz_min will be read.

Description

Search for a property in a device node and read 64-bit value(s) from it.

The out_values is modified only if a valid u64 value can be decoded.

Return

The number of elements read on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EOVERFLOW if the property data is smaller than sz_min or longer than sz_max.

int of_property_read_string(const struct device_node *np, const char *propname, const char **out_string)

Find and read a string from a property

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

const char **out_string

pointer to null terminated return string, modified only if return value is 0.

Description

Search for a property in a device tree node and retrieve a null terminated string value (pointer to data, not a copy).

Note that the empty string "" has length of 1, thus -ENODATA cannot be interpreted as an empty string.

The out_string pointer is modified only if a valid string can be decoded.

Return

0 on success, -EINVAL if the property does not exist, -ENODATA if property does not have a value, and -EILSEQ if the string is not null-terminated within the length of the property data.

int of_property_match_string(const struct device_node *np, const char *propname, const char *string)

Find string in a list and return index

Parameters

const struct device_node *np

pointer to node containing string list property

const char *propname

string list property name

const char *string

pointer to string to search for in string list

Description

This function searches a string list property and returns the index of a specific string value.

int of_property_read_string_helper(const struct device_node *np, const char *propname, const char **out_strs, size_t sz, int skip)

Utility helper for parsing string properties

Parameters

const struct device_node *np

device node from which the property value is to be read.

const char *propname

name of the property to be searched.

const char **out_strs

output array of string pointers.

size_t sz

number of array elements to read.

int skip

Number of strings to skip over at beginning of list.

Description

Don't call this function directly. It is a utility helper for the of_property_read_string*() family of functions.

int of_graph_parse_endpoint(const struct device_node *node, struct of_endpoint *endpoint)

parse common endpoint node properties

Parameters

const struct device_node *node

pointer to endpoint device_node

struct of_endpoint *endpoint

pointer to the OF endpoint data structure

Description

The caller should hold a reference to node.

struct device_node *of_graph_get_port_by_id(struct device_node *parent, u32 id)

get the port matching a given id

Parameters

struct device_node *parent

pointer to the parent device node

u32 id

id of the port

Return

A 'port' node pointer with refcount incremented. The caller has to use of_node_put() on it when done.

struct device_node *of_graph_get_next_endpoint(const struct device_node *parent, struct device_node *prev)

get next endpoint node

Parameters

const struct device_node *parent

pointer to the parent device node

struct device_node *prev

previous endpoint node, or NULL to get first

Return

An 'endpoint' node pointer with refcount incremented. Refcount of the passed prev node is decremented.

struct device_node *of_graph_get_endpoint_by_regs(const struct device_node *parent, int port_reg, int reg)

get endpoint node of specific identifiers

Parameters

const struct device_node *parent

pointer to the parent device node

int port_reg

identifier (value of reg property) of the parent port node

int reg

identifier (value of reg property) of the endpoint node

Return

An 'endpoint' node pointer which is identified by reg and at the same is the child of a port node identified by port_reg. reg and port_reg are ignored when they are -1. Use of_node_put() on the pointer when done.

struct device_node *of_graph_get_remote_endpoint(const struct device_node *node)

get remote endpoint node

Parameters

const struct device_node *node

pointer to a local endpoint device_node

Return

Remote endpoint node associated with remote endpoint node linked

to node. Use of_node_put() on it when done.

struct device_node *of_graph_get_port_parent(struct device_node *node)

get port's parent node

Parameters

struct device_node *node

pointer to a local endpoint device_node

Return

device node associated with endpoint node linked

to node. Use of_node_put() on it when done.

struct device_node *of_graph_get_remote_port_parent(const struct device_node *node)

get remote port's parent node

Parameters

const struct device_node *node

pointer to a local endpoint device_node

Return

Remote device node associated with remote endpoint node linked

to node. Use of_node_put() on it when done.

struct device_node *of_graph_get_remote_port(const struct device_node *node)

get remote port node

Parameters

const struct device_node *node

pointer to a local endpoint device_node

Return

Remote port node associated with remote endpoint node linked to node. Use of_node_put() on it when done.

struct device_node *of_graph_get_remote_node(const struct device_node *node, u32 port, u32 endpoint)

get remote parent device_node for given port/endpoint

Parameters

const struct device_node *node

pointer to parent device_node containing graph port/endpoint

u32 port

identifier (value of reg property) of the parent port node

u32 endpoint

identifier (value of reg property) of the endpoint node

Return

Remote device node associated with remote endpoint node linked to node. Use of_node_put() on it when done.

struct of_endpoint

the OF graph endpoint data structure

Definition:

struct of_endpoint {
    unsigned int port;
    unsigned int id;
    const struct device_node *local_node;
};

Members

port

identifier (value of reg property) of a port this endpoint belongs to

id

identifier (value of reg property) of this endpoint

local_node

pointer to device_node of this endpoint

for_each_endpoint_of_node

for_each_endpoint_of_node (parent, child)

iterate over every endpoint in a device node

Parameters

parent

parent device node containing ports and endpoints

child

loop variable pointing to the current endpoint node

Description

When breaking out of the loop, of_node_put(child) has to be called manually.

const __be32 *of_translate_dma_region(struct device_node *dev, const __be32 *prop, phys_addr_t *start, size_t *length)

Translate device tree address and size tuple

Parameters

struct device_node *dev

device tree node for which to translate

const __be32 *prop

pointer into array of cells

phys_addr_t *start

return value for the start of the DMA range

size_t *length

return value for the length of the DMA range

Description

Returns a pointer to the cell immediately following the translated DMA region.

int of_property_read_reg(struct device_node *np, int idx, u64 *addr, u64 *size)

Retrieve the specified "reg" entry index without translating

Parameters

struct device_node *np

device tree node for which to retrieve "reg" from

int idx

"reg" entry index to read

u64 *addr

return value for the untranslated address

u64 *size

return value for the entry size

Description

Returns -EINVAL if "reg" is not found. Returns 0 on success with addr and size values filled in.

bool of_dma_is_coherent(struct device_node *np)

Check if device is coherent

Parameters

struct device_node *np

device node

Description

It returns true if "dma-coherent" property was found for this device in the DT, or if DMA is coherent by default for OF devices on the current platform and no "dma-noncoherent" property was found for this device.

int of_address_to_resource(struct device_node *dev, int index, struct resource *r)

Translate device tree address and return as resource

Parameters

struct device_node *dev

Caller's Device Node

int index

Index into the array

struct resource *r

Pointer to resource array

Description

Returns -EINVAL if the range cannot be converted to resource.

Note that if your address is a PIO address, the conversion will fail if the physical address can't be internally converted to an IO token with pci_address_to_pio(), that is because it's either called too early or it can't be matched to any host bridge IO space

void __iomem *of_iomap(struct device_node *np, int index)

Maps the memory mapped IO for a given device_node

Parameters

struct device_node *np

the device whose io range will be mapped

int index

index of the io range

Description

Returns a pointer to the mapped memory

unsigned int irq_of_parse_and_map(struct device_node *dev, int index)

Parse and map an interrupt into linux virq space

Parameters

struct device_node *dev

Device node of the device whose interrupt is to be mapped

int index

Index of the interrupt to map

Description

This function is a wrapper that chains of_irq_parse_one() and irq_create_of_mapping() to make things easier to callers

struct device_node *of_irq_find_parent(struct device_node *child)

Given a device node, find its interrupt parent node

Parameters

struct device_node *child

pointer to device node

Return

A pointer to the interrupt parent node, or NULL if the interrupt parent could not be determined.

int of_irq_parse_raw(const __be32 *addr, struct of_phandle_args *out_irq)

Low level interrupt tree parsing

Parameters

const __be32 *addr

address specifier (start of "reg" property of the device) in be32 format

struct of_phandle_args *out_irq

structure of_phandle_args updated by this function

Description

This function is a low-level interrupt tree walking function. It can be used to do a partial walk with synthetized reg and interrupts properties, for example when resolving PCI interrupts when no device node exist for the parent. It takes an interrupt specifier structure as input, walks the tree looking for any interrupt-map properties, translates the specifier for each map, and then returns the translated map.

Return

0 on success and a negative number on error

int of_irq_parse_one(struct device_node *device, int index, struct of_phandle_args *out_irq)

Resolve an interrupt for a device

Parameters

struct device_node *device

the device whose interrupt is to be resolved

int index

index of the interrupt to resolve

struct of_phandle_args *out_irq

structure of_phandle_args filled by this function

Description

This function resolves an interrupt for a node by walking the interrupt tree, finding which interrupt controller node it is attached to, and returning the interrupt specifier that can be used to retrieve a Linux IRQ number.

int of_irq_to_resource(struct device_node *dev, int index, struct resource *r)

Decode a node's IRQ and return it as a resource

Parameters

struct device_node *dev

pointer to device tree node

int index

zero-based index of the irq

struct resource *r

pointer to resource structure to return result into.

int of_irq_get(struct device_node *dev, int index)

Decode a node's IRQ and return it as a Linux IRQ number

Parameters

struct device_node *dev

pointer to device tree node

int index

zero-based index of the IRQ

Return

Linux IRQ number on success, or 0 on the IRQ mapping failure, or -EPROBE_DEFER if the IRQ domain is not yet created, or error code in case of any other failure.

int of_irq_get_byname(struct device_node *dev, const char *name)

Decode a node's IRQ and return it as a Linux IRQ number

Parameters

struct device_node *dev

pointer to device tree node

const char *name

IRQ name

Return

Linux IRQ number on success, or 0 on the IRQ mapping failure, or -EPROBE_DEFER if the IRQ domain is not yet created, or error code in case of any other failure.

int of_irq_to_resource_table(struct device_node *dev, struct resource *res, int nr_irqs)

Fill in resource table with node's IRQ info

Parameters

struct device_node *dev

pointer to device tree node

struct resource *res

array of resources to fill in

int nr_irqs

the number of IRQs (and upper bound for num of res elements)

Return

The size of the filled in table (up to nr_irqs).

struct irq_domain *of_msi_get_domain(struct device *dev, struct device_node *np, enum irq_domain_bus_token token)

Use msi-parent to find the relevant MSI domain

Parameters

struct device *dev

device for which the domain is requested

struct device_node *np

device node for dev

enum irq_domain_bus_token token

bus type for this domain

Description

Parse the msi-parent property (both the simple and the complex versions), and returns the corresponding MSI domain.

Return

the MSI domain for this device (or NULL on failure).

void of_msi_configure(struct device *dev, struct device_node *np)

Set the msi_domain field of a device

Parameters

struct device *dev

device structure to associate with an MSI irq domain

struct device_node *np

device node for that device

void *of_fdt_unflatten_tree(const unsigned long *blob, struct device_node *dad, struct device_node **mynodes)

create tree of device_nodes from flat blob

Parameters

const unsigned long *blob

Flat device tree blob

struct device_node *dad

Parent device node

struct device_node **mynodes

The device tree created by the call

Description

unflattens the device-tree passed by the firmware, creating the tree of struct device_node. It also fills the "name" and "type" pointers of the nodes so the normal device-tree walking functions can be used.

Return

NULL on failure or the memory chunk containing the unflattened device tree on success.

Driver model functions

int of_driver_match_device(struct device *dev, const struct device_driver *drv)

Tell if a driver's of_match_table matches a device.

Parameters

struct device *dev

the device structure to match against

const struct device_driver *drv

the device_driver structure to test

const struct of_device_id *of_match_device(const struct of_device_id *matches, const struct device *dev)

Tell if a struct device matches an of_device_id list

Parameters

const struct of_device_id *matches

array of of device match structures to search in

const struct device *dev

the of device structure to match against

Description

Used by a driver to check whether an platform_device present in the system is in its list of supported devices.

int of_dma_configure_id(struct device *dev, struct device_node *np, bool force_dma, const u32 *id)

Setup DMA configuration

Parameters

struct device *dev

Device to apply DMA configuration

struct device_node *np

Pointer to OF node having DMA configuration

bool force_dma

Whether device is to be set up by of_dma_configure() even if DMA capability is not explicitly described by firmware.

const u32 *id

Optional const pointer value input id

Description

Try to get devices's DMA configuration from DT and update it accordingly.

If platform code needs to use its own special DMA configuration, it can use a platform bus notifier and handle BUS_NOTIFY_ADD_DEVICE events to fix up DMA configuration.

ssize_t of_device_modalias(struct device *dev, char *str, ssize_t len)

Fill buffer with newline terminated modalias string

Parameters

struct device *dev

Calling device

char *str

Modalias string

ssize_t len

Size of str

void of_device_uevent(const struct device *dev, struct kobj_uevent_env *env)

Display OF related uevent information

Parameters

const struct device *dev

Device to display the uevent information for

struct kobj_uevent_env *env

Kernel object's userspace event reference to fill up

struct of_dev_auxdata

lookup table entry for device names & platform_data

Definition:

struct of_dev_auxdata {
    char *compatible;
    resource_size_t phys_addr;
    char *name;
    void *platform_data;
};

Members

compatible

compatible value of node to match against node

phys_addr

Start address of registers to match against node

name

Name to assign for matching nodes

platform_data

platform_data to assign for matching nodes

Description

This lookup table allows the caller of of_platform_populate() to override the names of devices when creating devices from the device tree. The table should be terminated with an empty entry. It also allows the platform_data pointer to be set.

The reason for this functionality is that some Linux infrastructure uses the device name to look up a specific device, but the Linux-specific names are not encoded into the device tree, so the kernel needs to provide specific values.

Note

Using an auxdata lookup table should be considered a last resort when converting a platform to use the DT. Normally the automatically generated device name will not matter, and drivers should obtain data from the device node instead of from an anonymous platform_data pointer.

struct platform_device *of_find_device_by_node(struct device_node *np)

Find the platform_device associated with a node

Parameters

struct device_node *np

Pointer to device tree node

Description

Takes a reference to the embedded struct device which needs to be dropped after use.

Return

platform_device pointer, or NULL if not found

struct platform_device *of_device_alloc(struct device_node *np, const char *bus_id, struct device *parent)

Allocate and initialize an of_device

Parameters

struct device_node *np

device node to assign to device

const char *bus_id

Name to assign to the device. May be null to use default name.

struct device *parent

Parent device.

struct platform_device *of_platform_device_create(struct device_node *np, const char *bus_id, struct device *parent)

Alloc, initialize and register an of_device

Parameters

struct device_node *np

pointer to node to create device for

const char *bus_id

name to assign device

struct device *parent

Linux device model parent device.

Return

Pointer to created platform device, or NULL if a device was not registered. Unavailable devices will not get registered.

int of_platform_bus_probe(struct device_node *root, const struct of_device_id *matches, struct device *parent)

Probe the device-tree for platform buses

Parameters

struct device_node *root

parent of the first level to probe or NULL for the root of the tree

const struct of_device_id *matches

match table for bus nodes

struct device *parent

parent to hook devices from, NULL for toplevel

Description

Note that children of the provided root are not instantiated as devices unless the specified root itself matches the bus list and is not NULL.

int of_platform_populate(struct device_node *root, const struct of_device_id *matches, const struct of_dev_auxdata *lookup, struct device *parent)

Populate platform_devices from device tree data

Parameters

struct device_node *root

parent of the first level to probe or NULL for the root of the tree

const struct of_device_id *matches

match table, NULL to use the default

const struct of_dev_auxdata *lookup

auxdata table for matching id and platform_data with device nodes

struct device *parent

parent to hook devices from, NULL for toplevel

Description

Similar to of_platform_bus_probe(), this function walks the device tree and creates devices from nodes. It differs in that it follows the modern convention of requiring all device nodes to have a 'compatible' property, and it is suitable for creating devices which are children of the root node (of_platform_bus_probe will only create children of the root which are selected by the matches argument).

New board support should be using this function instead of of_platform_bus_probe().

Return

0 on success, < 0 on failure.

void of_platform_depopulate(struct device *parent)

Remove devices populated from device tree

Parameters

struct device *parent

device which children will be removed

Description

Complementary to of_platform_populate(), this function removes children of the given device (and, recurrently, their children) that have been created from their respective device tree nodes (and only those, leaving others - eg. manually created - unharmed).

int devm_of_platform_populate(struct device *dev)

Populate platform_devices from device tree data

Parameters

struct device *dev

device that requested to populate from device tree data

Description

Similar to of_platform_populate(), but will automatically call of_platform_depopulate() when the device is unbound from the bus.

Return

0 on success, < 0 on failure.

void devm_of_platform_depopulate(struct device *dev)

Remove devices populated from device tree

Parameters

struct device *dev

device that requested to depopulate from device tree data

Description

Complementary to devm_of_platform_populate(), this function removes children of the given device (and, recurrently, their children) that have been created from their respective device tree nodes (and only those, leaving others - eg. manually created - unharmed).

Overlay and Dynamic DT functions

int of_resolve_phandles(struct device_node *overlay)

Relocate and resolve overlay against live tree

Parameters

struct device_node *overlay

Pointer to devicetree overlay to relocate and resolve

Description

Modify (relocate) values of local phandles in overlay to a range that does not conflict with the live expanded devicetree. Update references to the local phandles in overlay. Update (resolve) phandle references in overlay that refer to the live expanded devicetree.

Phandle values in the live tree are in the range of 1 .. live_tree_max_phandle(). The range of phandle values in the overlay also begin with at 1. Adjust the phandle values in the overlay to begin at live_tree_max_phandle() + 1. Update references to the phandles to the adjusted phandle values.

The name of each property in the "__fixups__" node in the overlay matches the name of a symbol (a label) in the live tree. The values of each property in the "__fixups__" node is a list of the property values in the overlay that need to be updated to contain the phandle reference corresponding to that symbol in the live tree. Update the references in the overlay with the phandle values in the live tree.

overlay must be detached.

Resolving and applying overlay to the live expanded devicetree must be protected by a mechanism to ensure that multiple overlays are processed in a single threaded manner so that multiple overlays will not relocate phandles to overlapping ranges. The mechanism to enforce this is not yet implemented.

Return

0 on success or a negative error value on error.

struct device_node *of_node_get(struct device_node *node)

Increment refcount of a node

Parameters

struct device_node *node

Node to inc refcount, NULL is supported to simplify writing of callers

Return

The node with refcount incremented.

void of_node_put(struct device_node *node)

Decrement refcount of a node

Parameters

struct device_node *node

Node to dec refcount, NULL is supported to simplify writing of callers

int of_detach_node(struct device_node *np)

"Unplug" a node from the device tree.

Parameters

struct device_node *np

Pointer to the caller's Device Node

struct device_node *of_changeset_create_node(struct of_changeset *ocs, struct device_node *parent, const char *full_name)

Dynamically create a device node and attach to a given changeset.

Parameters

struct of_changeset *ocs

Pointer to changeset

struct device_node *parent

Pointer to parent device node

const char *full_name

Node full name

Return

Pointer to the created device node or NULL in case of an error.

void of_changeset_init(struct of_changeset *ocs)

Initialize a changeset for use

Parameters

struct of_changeset *ocs

changeset pointer

Description

Initialize a changeset structure

void of_changeset_destroy(struct of_changeset *ocs)

Destroy a changeset

Parameters

struct of_changeset *ocs

changeset pointer

Description

Destroys a changeset. Note that if a changeset is applied, its changes to the tree cannot be reverted.

int of_changeset_apply(struct of_changeset *ocs)

Applies a changeset

Parameters

struct of_changeset *ocs

changeset pointer

Description

Applies a changeset to the live tree. Any side-effects of live tree state changes are applied here on success, like creation/destruction of devices and side-effects like creation of sysfs properties and directories.

Return

0 on success, a negative error value in case of an error. On error the partially applied effects are reverted.

int of_changeset_revert(struct of_changeset *ocs)

Reverts an applied changeset

Parameters

struct of_changeset *ocs

changeset pointer

Description

Reverts a changeset returning the state of the tree to what it was before the application. Any side-effects like creation/destruction of devices and removal of sysfs properties and directories are applied.

Return

0 on success, a negative error value in case of an error.

int of_changeset_action(struct of_changeset *ocs, unsigned long action, struct device_node *np, struct property *prop)

Add an action to the tail of the changeset list

Parameters

struct of_changeset *ocs

changeset pointer

unsigned long action

action to perform

struct device_node *np

Pointer to device node

struct property *prop

Pointer to property

Description

On action being one of: + OF_RECONFIG_ATTACH_NODE + OF_RECONFIG_DETACH_NODE, + OF_RECONFIG_ADD_PROPERTY + OF_RECONFIG_REMOVE_PROPERTY, + OF_RECONFIG_UPDATE_PROPERTY

Return

0 on success, a negative error value in case of an error.

int of_changeset_add_prop_string(struct of_changeset *ocs, struct device_node *np, const char *prop_name, const char *str)

Add a string property to a changeset

Parameters

struct of_changeset *ocs

changeset pointer

struct device_node *np

device node pointer

const char *prop_name

name of the property to be added

const char *str

pointer to null terminated string

Description

Create a string property and add it to a changeset.

Return

0 on success, a negative error value in case of an error.

int of_changeset_add_prop_string_array(struct of_changeset *ocs, struct device_node *np, const char *prop_name, const char **str_array, size_t sz)

Add a string list property to a changeset

Parameters

struct of_changeset *ocs

changeset pointer

struct device_node *np

device node pointer

const char *prop_name

name of the property to be added

const char **str_array

pointer to an array of null terminated strings

size_t sz

number of string array elements

Description

Create a string list property and add it to a changeset.

Return

0 on success, a negative error value in case of an error.

int of_changeset_add_prop_u32_array(struct of_changeset *ocs, struct device_node *np, const char *prop_name, const u32 *array, size_t sz)

Add a property of 32 bit integers property to a changeset

Parameters

struct of_changeset *ocs

changeset pointer

struct device_node *np

device node pointer

const char *prop_name

name of the property to be added

const u32 *array

pointer to an array of 32 bit integers

size_t sz

number of array elements

Description

Create a property of 32 bit integers and add it to a changeset.

Return

0 on success, a negative error value in case of an error.

int of_overlay_notifier_register(struct notifier_block *nb)

Register notifier for overlay operations

Parameters

struct notifier_block *nb

Notifier block to register

Description

Register for notification on overlay operations on device tree nodes. The reported actions definied by of_reconfig_change. The notifier callback furthermore receives a pointer to the affected device tree node.

Note that a notifier callback is not supposed to store pointers to a device tree node or its content beyond OF_OVERLAY_POST_REMOVE corresponding to the respective node it received.

int of_overlay_notifier_unregister(struct notifier_block *nb)

Unregister notifier for overlay operations

Parameters

struct notifier_block *nb

Notifier block to unregister

int of_overlay_remove(int *ovcs_id)

Revert and free an overlay changeset

Parameters

int *ovcs_id

Pointer to overlay changeset id

Description

Removes an overlay if it is permissible. ovcs_id was previously returned by of_overlay_fdt_apply().

If an error occurred while attempting to revert the overlay changeset, then an attempt is made to re-apply any changeset entry that was reverted. If an error occurs on re-apply then the state of the device tree can not be determined, and any following attempt to apply or remove an overlay changeset will be refused.

A non-zero return value will not revert the changeset if error is from:
  • parameter checks

  • overlay changeset pre-remove notifier

  • overlay changeset entry revert

If an error is returned by an overlay changeset pre-remove notifier then no further overlay changeset pre-remove notifier will be called.

If more than one notifier returns an error, then the last notifier error to occur is returned.

A non-zero return value will revert the changeset if error is from:
  • overlay changeset entry notifier

  • overlay changeset post-remove notifier

If an error is returned by an overlay changeset post-remove notifier then no further overlay changeset post-remove notifier will be called.

Return

0 on success, or a negative error number. *ovcs_id is set to zero after reverting the changeset, even if a subsequent error occurs.

int of_overlay_remove_all(void)

Reverts and frees all overlay changesets

Parameters

void

no arguments

Description

Removes all overlays from the system in the correct order.

Return

0 on success, or a negative error number