The latest development version of this page may be more current than this released 4.0.0 version.

Custom Kconfig Preprocessor Functions

Kconfiglib supports custom Kconfig preprocessor functions written in Python. These functions are defined in scripts/kconfig/kconfigfunctions.py.

Note

The official Kconfig preprocessor documentation can be found here.

See the Python docstrings in scripts/kconfig/kconfigfunctions.py for detailed documentation. 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. The *_int version of each function returns the value as a decimal integer, while the *_hex version returns a hexadecimal value starting with 0x.

$(dt_alias_enabled,<node alias>)
$(dt_chosen_bool_prop, <property in /chosen>, <prop>)
$(dt_chosen_enabled,<property in /chosen>)
$(dt_chosen_has_compat,<property in /chosen>,<compatible string>)
$(dt_chosen_label,<property in /chosen>)
$(dt_chosen_partition,addr_hex,<chosen>[,<index>,<unit>])
$(dt_chosen_partition,addr_int,<chosen>[,<index>,<unit>])
$(dt_chosen_path,<property in /chosen>)
$(dt_chosen_reg_addr_hex,<property in /chosen>[,<index>,<unit>])
$(dt_chosen_reg_addr_int,<property in /chosen>[,<index>,<unit>])
$(dt_chosen_reg_size_hex,<property in /chosen>[,<index>,<unit>])
$(dt_chosen_reg_size_int,<property in /chosen>[,<index>,<unit>])
$(dt_compat_any_has_prop,<compatible string>,<prop>[,<value>])
$(dt_compat_any_on_bus,<compatible string>,<prop>)
$(dt_compat_enabled,<compatible string>)
$(dt_compat_on_bus,<compatible string>,<bus>)
$(dt_gpio_hogs_enabled)
$(dt_has_compat,<compatible string>)
$(dt_node_array_prop_hex,<node path>,<prop>,<index>[,<unit>])
$(dt_node_array_prop_int,<node path>,<prop>,<index>[,<unit>])
$(dt_node_bool_prop,<node path>,<prop>)
$(dt_node_has_compat,<node path>,<compatible string>)
$(dt_node_has_prop,<node path>,<prop>)
$(dt_node_int_prop_hex,<node path>,<prop>[,<unit>])
$(dt_node_int_prop_int,<node path>,<prop>[,<unit>])
$(dt_node_parent,<node path>)
$(dt_node_ph_array_prop_hex,<node path>,<prop>,<index>,<cell>[,<unit>])
$(dt_node_ph_array_prop_int,<node path>,<prop>,<index>,<cell>[,<unit>])
$(dt_node_ph_prop_path,<node path>,<prop>)
$(dt_node_reg_addr_hex,<node path>[,<index>,<unit>])
$(dt_node_reg_addr_int,<node path>[,<index>,<unit>])
$(dt_node_reg_size_hex,<node path>[,<index>,<unit>])
$(dt_node_reg_size_int,<node path>[,<index>,<unit>])
$(dt_node_str_prop_equals,<node path>,<prop>,<value>)
$(dt_nodelabel_array_prop_has_val, <node label>, <prop>, <value>)
$(dt_nodelabel_bool_prop,<node label>,<prop>)
$(dt_nodelabel_enabled,<node label>)
$(dt_nodelabel_enabled_with_compat,<node label>,<compatible string>)
$(dt_nodelabel_has_compat,<node label>,<compatible string>)
$(dt_nodelabel_has_prop,<node label>,<prop>)
$(dt_nodelabel_path,<node label>)
$(dt_nodelabel_reg_addr_hex,<node label>[,<index>,<unit>])
$(dt_nodelabel_reg_addr_int,<node label>[,<index>,<unit>])
$(dt_nodelabel_reg_size_hex,<node label>[,<index>,<unit>])
$(dt_nodelabel_reg_size_int,<node label>[,<index>,<unit>])
$(dt_path_enabled,<node path>)

Integer functions

The functions listed below can be used to do arithmetic operations on integer variables, such as addition, subtraction and more.

$(add,<value>[,value]...)
$(dec,<value>[,value]...)
$(div,<value>[,value]...)
$(inc,<value>[,value]...)
$(max,<value>[,value]...)
$(min,<value>[,value]...)
$(mod,<value>[,value]...)
$(mul,<value>[,value]...)
$(sub,<value>[,value]...)

String functions

The functions listed below can be used to modify string variables.

$(normalize_upper,<string>)
$(substring,<string>,<start>[,<stop>])

Other functions

Functions to perform specific operations, currently only a check if a shield name is specified.

$(shields_list_contains,<shield name>)

Example Usage

Assume that the devicetree for some board looks like this:

{
     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:

config FLASH_BASE_ADDRESS
     default $(dt_node_reg_addr_hex,/soc/spi@1001400,1)

After preprocessor expansion, this turns into the definition below:

config FLASH_BASE_ADDRESS
     default 0x20010000