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devicetree: add DT_CHILD()

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Helper macro to get a node_id for a child node of a given node_id.

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>
This commit is contained in:
Kumar Gala 2020-03-31 21:24:42 -05:00 • committed by Kumar Gala
commit 2535f81b76
2 changed files with 32 additions and 0 deletions
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26
include/devicetree.h
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@ -208,6 +208,32 @@
*/
#define DT_INST(inst, compat) UTIL_CAT(DT_N_INST, DT_DASH(inst, compat))
/**
* @brief Get a node identifier for a child node
*
* Example devicetree fragment:
*
* / {
* soc-label: soc {
* my-serial: serial@4 {
* status = "okay";
* current-speed = <115200>;
* ...
* };
* };
* };
*
* Example usage with @ref DT_PROP() to get the status of the child node
* "serial@4" of the node referenced by node label "soc-label":
*
* DT_PROP(DT_CHILD(DT_NODELABEL(soc_label), serial_4), status) // "okay"
*
* @param node_id node identifier
* @param child lowercase-and-underscores child node name
* @return node identifier for the node with the name referred to by 'child'
*/
#define DT_CHILD(node_id, child) UTIL_CAT(node_id, DT_S_PREFIX(child))
/**
* @}
*/

6
tests/lib/devicetree/src/main.c
View file

@ -899,6 +899,12 @@ static void test_macro_names(void)
zassert_true(!strcmp(TO_STRING(DT_NODELABEL(test_nodelabel_allcaps)),
"DT_N_S_test_S_gpio_deadbeef"),
"nodelabel (all caps)");
#define CHILD_NODE_ID DT_CHILD(DT_PATH(test, i2c_11112222), test_i2c_dev_10)
#define FULL_PATH_ID DT_PATH(test, i2c_11112222, test_i2c_dev_10)
zassert_true(!strcmp(TO_STRING(CHILD_NODE_ID), TO_STRING(FULL_PATH_ID)),
"child");
}
static int a[] = DT_PROP(TEST_ARRAYS, a);