zephyr/doc/build/kconfig/preprocessor-functions.rst

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.. _kconfig-functions:
Custom Kconfig Preprocessor Functions
#####################################
Kconfiglib supports custom Kconfig preprocessor functions written in Python.
These functions are defined in
:zephyr_file:`scripts/kconfig/kconfigfunctions.py`.
.. note::
The official Kconfig preprocessor documentation can be found `here
<https://www.kernel.org/doc/html/latest/kbuild/kconfig-macro-language.html>`__.
Most of the custom preprocessor functions are used to get devicetree
information into Kconfig. For example, the default value of a Kconfig symbol
can be fetched from a devicetree ``reg`` property.
Devicetree-related Functions
****************************
The functions listed below are used to get devicetree information into Kconfig.
See the Python docstrings in :zephyr_file:`scripts/kconfig/kconfigfunctions.py`
for detailed documentation.
The ``*_int`` version of each function returns the value as a decimal integer,
while the ``*_hex`` version returns a hexadecimal value starting with ``0x``.
.. code-block:: none
$(dt_has_compat,<compatible string>)
$(dt_compat_enabled,<compatible string>)
$(dt_compat_on_bus,<compatible string>,<bus>)
$(dt_chosen_label,<property in /chosen>)
$(dt_chosen_enabled,<property in /chosen>)
$(dt_chosen_path,<property in /chosen>)
$(dt_chosen_has_compat,<property in /chosen>)
$(dt_path_enabled,<node path>)
$(dt_alias_enabled,<node alias>)
$(dt_nodelabel_enabled,<node label>)
$(dt_nodelabel_enabled_with_compat,<node label>,<compatible string>)
$(dt_chosen_reg_addr_int,<property in /chosen>[,<index>,<unit>])
$(dt_chosen_reg_addr_hex,<property in /chosen>[,<index>,<unit>])
$(dt_chosen_reg_size_int,<property in /chosen>[,<index>,<unit>])
$(dt_chosen_reg_size_hex,<property in /chosen>[,<index>,<unit>])
$(dt_node_reg_addr_int,<node path>[,<index>,<unit>])
$(dt_node_reg_addr_hex,<node path>[,<index>,<unit>])
$(dt_node_reg_size_int,<node path>[,<index>,<unit>])
$(dt_node_reg_size_hex,<node path>[,<index>,<unit>])
$(dt_compat_enabled,<compatible string>)
$(dt_chosen_enabled,<property in /chosen>)
$(dt_node_bool_prop,<node path>,<prop>)
$(dt_nodelabel_bool_prop,<node label>,<prop>)
$(dt_node_has_prop,<node path>,<prop>)
$(dt_nodelabel_has_prop,<node label>,<prop>)
$(dt_node_int_prop_int,<node path>,<prop>[,<unit>])
$(dt_node_int_prop_hex,<node path>,<prop>[,<unit>])
$(dt_node_str_prop_equals,<node path>,<prop>,<value>)
$(dt_nodelabel_has_compat,<node label>,<compatible string>)
$(dt_nodelabel_path,<node label>)
$(shields_list_contains,<shield name>)
Example Usage
=============
Assume that the devicetree for some board looks like this:
.. code-block:: none
{
soc {
#address-cells = <1>;
#size-cells = <1>;
spi0: spi@10014000 {
compatible = "sifive,spi0";
reg = <0x10014000 0x1000 0x20010000 0x3c0900>;
reg-names = "control", "mem";
...
};
};
The second entry in ``reg`` in ``spi@1001400`` (``<0x20010000 0x3c0900>``)
corresponds to ``mem``, and has the address ``0x20010000``. This address can be
inserted into Kconfig as follows:
.. code-block:: none
config FLASH_BASE_ADDRESS
default $(dt_node_reg_addr_hex,/soc/spi@1001400,1)
After preprocessor expansion, this turns into the definition below:
.. code-block:: none
config FLASH_BASE_ADDRESS
default 0x20010000