Tab5 power expander driver and devicetree parsing improvements (#507)

* **New Features**
  * PI4IOE5V6408 I2C I/O expander driver with public GPIO APIs
  * CLI tool to list devicetree dependencies

* **Device Tree Updates**
  * M5Stack Tab5 configured with two I2C IO expanders; PI4IOE5V6408 binding added

* **Build / Tooling**
  * Devicetree code generation integrated into build; generated artifacts and dynamic dependency resolution exposed

* **Refactor**
  * Kernel/run APIs updated to accept a null‑terminated devicetree modules array; many module symbols renamed

* **Documentation**
  * Added README and Apache‑2.0 license for new driver module

TactilityKernel/bindings/i2c-device.yaml

@@ -1,6 +1,6 @@
 description: I2C device
 
 properties:
-  register:
+  reg:
     required: true
     description: device address on the bus

TactilityKernel/include/tactility/kernel_init.h

@@ -1,21 +1,20 @@
 #pragma once
 
+#include <tactility/dts.h>
+#include <tactility/error.h>
+#include <tactility/module.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#include <tactility/device.h>
-#include <tactility/error.h>
-#include <tactility/module.h>
-
 /**
- * Initialize the kernel with platform and device modules, and a device tree.
- * @param platform_module The platform module to start. This module should not be constructed yet.
- * @param device_module The device module to start. This module should not be constructed yet. This parameter can be NULL.
- * @param dts_devices The list of generated devices from the devicetree. The array must be terminated with DTS_DEVICE_TERMINATOR. This parameter can be NULL.
+ * Initialize the kernel with the provided modules from the device tree
+ * @param dts_modules List of modules from devicetree, null-terminated. Non-null parameter.
+ * @param dts_devices The list of generated devices from the devicetree. The array must be terminated with DTS_DEVICE_TERMINATOR. Non-null parameter.
  * @return ERROR_NONE on success, otherwise an error code
  */
-error_t kernel_init(struct Module* platform_module, struct Module* device_module, struct DtsDevice dts_devices[]);
+error_t kernel_init(struct Module* dts_modules[], struct DtsDevice dts_devices[]);
 
 #ifdef __cplusplus
 }

TactilityKernel/include/tactility/module.h

@@ -3,6 +3,7 @@
 
 #include "error.h"
 #include <stdbool.h>
+#include <stddef.h>
 #include <stdint.h>
 
 #ifdef __cplusplus

TactilityKernel/source/kernel_init.cpp

@@ -1,5 +1,6 @@
-#include "tactility/dts.h"
 #include <tactility/kernel_init.h>
+
+#include <tactility/device.h>
 #include <tactility/log.h>
 
 #ifdef __cplusplus
@@ -8,7 +9,7 @@ extern "C" {
 
 #define TAG "kernel"
 
-extern const struct ModuleSymbol KERNEL_SYMBOLS[];
+extern const ModuleSymbol KERNEL_SYMBOLS[];
 
 static error_t start() {
     extern Driver root_driver;
@@ -20,7 +21,7 @@ static error_t stop() {
     return ERROR_NONE;
 }
 
-struct Module root_module = {
+Module root_module = {
     .name = "kernel",
     .start = start,
     .stop = stop,
@@ -28,7 +29,7 @@ struct Module root_module = {
     .internal = nullptr
 };
 
-error_t kernel_init(struct Module* platform_module, struct Module* device_module, struct DtsDevice dts_devices[]) {
+error_t kernel_init(Module* dts_modules[], DtsDevice dts_devices[]) {
     LOG_I(TAG, "init");
 
     if (module_construct_add_start(&root_module) != ERROR_NONE) {
@@ -36,36 +37,31 @@ error_t kernel_init(struct Module* platform_module, struct Module* device_module
         return ERROR_RESOURCE;
     }
 
-    if (module_construct_add_start(platform_module) != ERROR_NONE) {
-        LOG_E(TAG, "platform module init failed");
-        return ERROR_RESOURCE;
-    }
-
-    if (device_module != nullptr) {
-        if (module_construct_add_start(device_module) != ERROR_NONE) {
-            LOG_E(TAG, "device module init failed");
+    Module** dts_module = dts_modules;
+    while (*dts_module != nullptr) {
+        if (module_construct_add_start(*dts_module) != ERROR_NONE) {
+            LOG_E(TAG, "dts module init failed: %s", (*dts_module)->name);
             return ERROR_RESOURCE;
         }
+        dts_module++;
     }
 
-    if (dts_devices) {
-        DtsDevice* dts_device = dts_devices;
-        while (dts_device->device != nullptr) {
-            if (dts_device->status == DTS_DEVICE_STATUS_OKAY) {
-                if (device_construct_add_start(dts_device->device, dts_device->compatible) != ERROR_NONE) {
-                    LOG_E(TAG, "kernel_init failed to construct+add+start device: %s (%s)", dts_device->device->name, dts_device->compatible);
-                    return ERROR_RESOURCE;
-                }
-            } else if (dts_device->status == DTS_DEVICE_STATUS_DISABLED) {
-                if (device_construct_add(dts_device->device, dts_device->compatible) != ERROR_NONE) {
-                    LOG_E(TAG, "kernel_init failed to construct+add device: %s (%s)", dts_device->device->name, dts_device->compatible);
-                    return ERROR_RESOURCE;
-                }
-            } else {
-                check(false, "DTS status not implemented");
+    DtsDevice* dts_device = dts_devices;
+    while (dts_device->device != nullptr) {
+        if (dts_device->status == DTS_DEVICE_STATUS_OKAY) {
+            if (device_construct_add_start(dts_device->device, dts_device->compatible) != ERROR_NONE) {
+                LOG_E(TAG, "kernel_init failed to construct+add+start device: %s (%s)", dts_device->device->name, dts_device->compatible);
+                return ERROR_RESOURCE;
             }
-            dts_device++;
+        } else if (dts_device->status == DTS_DEVICE_STATUS_DISABLED) {
+            if (device_construct_add(dts_device->device, dts_device->compatible) != ERROR_NONE) {
+                LOG_E(TAG, "kernel_init failed to construct+add device: %s (%s)", dts_device->device->name, dts_device->compatible);
+                return ERROR_RESOURCE;
+            }
+        } else {
+            check(false, "DTS status not implemented");
         }
+        dts_device++;
     }
 
     LOG_I(TAG, "init done");