devicetree Arduino bindings do not support identification of bus controllers

[pabigot]

(split off from #20325)

The commit 442df97 (scripts/dts: Remove alias defines for labels) breaks the existing use of a node label to identify Arduino bus resources. The commit was incorrect in stating that the generated label was never used. There is one in-tree use, in samples/drivers/i2c_scanner.

If it is desirable to identify Arduino bus resources, then either a fix like the following must be applied to all Arduino binding overlays, or some new mechanism that generates macros based on node labels (not label property) must be added to the scripting.

diff --git a/boards/arm/nucleo_l476rg/arduino_r3_connector.dtsi b/boards/arm/nucleo_l476rg/arduino_r3_connector.dtsi
index 1f47915822..c6a37a6ffd 100644
--- a/boards/arm/nucleo_l476rg/arduino_r3_connector.dtsi
+++ b/boards/arm/nucleo_l476rg/arduino_r3_connector.dtsi
@@ -5,6 +5,9 @@
  */
 
 / {
+       aliases {
+               arduino-i2c = &i2c1;
+       };
        arduino_header: connector {
                compatible = "arduino-header-r3";
                #gpio-cells = <2>;
@@ -34,5 +37,3 @@
                           <21 0 &gpiob 8 0>;   /* D15 */
        };
 };
-
-arduino_i2c: &i2c1 {};
diff --git a/samples/drivers/i2c_scanner/src/main.c b/samples/drivers/i2c_scanner/src/main.c
index 44c1724377..ac71a0d85f 100644
--- a/samples/drivers/i2c_scanner/src/main.c
+++ b/samples/drivers/i2c_scanner/src/main.c
@@ -10,8 +10,8 @@
 #include <device.h>
 #include <drivers/i2c.h>
 
-#ifdef ARDUINO_I2C_LABEL
-#define I2C_DEV ARDUINO_I2C_LABEL
+#ifdef DT_ALIAS_ARDUINO_I2C_LABEL
+#define I2C_DEV DT_ALIAS_ARDUINO_I2C_LABEL
 #else
 #define I2C_DEV "I2C_0"
 #endif

[ulfalizer]

How do I reproduce this failure? The sample builds when I do

$ cmake -GNinja -DBOARD=arduino_due ..
$ ninja

Is it just a runtime failure?

[ulfalizer]

Ah... never mind. Didn't notice the last part of the diff.

[galak]

I think this will be resolved by the NODELABEL support from issue #22555 and PR #22612

[pabigot]

This now works:

diff --git a/samples/drivers/i2c_scanner/src/main.c b/samples/drivers/i2c_scanner/src/main.c
index 9e4d3cc86b..7fd0e47c79 100644
--- a/samples/drivers/i2c_scanner/src/main.c
+++ b/samples/drivers/i2c_scanner/src/main.c
@@ -10,8 +10,8 @@
 #include <device.h>
 #include <drivers/i2c.h>
 
-#ifdef ARDUINO_I2C_LABEL
-#define I2C_DEV ARDUINO_I2C_LABEL
+#if DT_HAS_NODE(DT_NODELABEL(arduino_i2c))
+#define I2C_DEV DT_LABEL(DT_NODELABEL(arduino_i2c))
 #else
 #define I2C_DEV "I2C_0"
 #endif