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

Buildscripts/DevicetreeCompiler/dependencies.py

@@ -0,0 +1,35 @@
+import sys
+import os
+
+from source.printing import print_error
+from source.config import parse_config
+
+def print_help():
+    print("Usage: python dependencies.py [path]\n")
+    print("\t[in_file]                 the path where the root devicetree.yaml file is")
+
+if __name__ == "__main__":
+    if "--help" in sys.argv:
+        print_help()
+        sys.exit()
+    args = [a for a in sys.argv[1:] if not a.startswith("--")]
+    if len(args) < 1:
+        print_error("Missing argument")
+        print_help()
+        sys.exit(1)
+
+    yaml_directory = args[0]
+    
+    if not os.path.exists(yaml_directory):
+        print_error(f"Path not found: {yaml_directory}")
+        sys.exit(1)
+
+    config = parse_config(yaml_directory, os.getcwd())
+
+    # Device module is added first because it's started first:
+    # It creates the root device, so it must exist before its children.
+    device_dependency = os.path.basename(os.path.normpath(yaml_directory))
+    print(device_dependency)
+    for dependency in config.dependencies:
+        dependency_name = os.path.basename(os.path.normpath(dependency))
+        print(dependency_name)

Buildscripts/DevicetreeCompiler/source/generator.py

@@ -212,7 +212,7 @@ def gather_devices(device: Device, output: list[Device]):
     for child_device in device.devices:
         gather_devices(child_device, output)
 
-def generate_devicetree_c(filename: str, items: list[object], bindings: list[Binding], verbose: bool):
+def generate_devicetree_c(filename: str, items: list[object], bindings: list[Binding], config, verbose: bool):
     # Create a cache for looking up device names and aliases easily
     # We still want to traverse it as a tree during code generation because of parent-setting
     devices = list()
@@ -225,6 +225,7 @@ def generate_devicetree_c(filename: str, items: list[object], bindings: list[Bin
         // Default headers
         #include <tactility/device.h>
         #include <tactility/dts.h>
+        #include <tactility/module.h>
         // DTS headers
         '''))
 
@@ -246,6 +247,25 @@ def generate_devicetree_c(filename: str, items: list[object], bindings: list[Bin
                 write_device_list_entry(file, item, bindings, verbose)
         file.write("\tDTS_DEVICE_TERMINATOR\n")
         file.write("};\n")
+        # Gather module symbols
+        module_symbol_names = []
+        for dependency in config.dependencies:
+            dependency_name = os.path.basename(os.path.normpath(dependency))
+            module_symbol_name = f"{dependency_name.replace('-', '_')}"
+            if not module_symbol_name.endswith("_module"):
+                module_symbol_name += "_module"
+            module_symbol_names.append(module_symbol_name)
+        file.write("\n")
+        # Forward declaration of symbol variables
+        for symbol in module_symbol_names:
+            file.write(f"extern struct Module {symbol};\n")
+        file.write("\n")
+        # Create array of symbol variables
+        file.write("struct Module* dts_modules[] = {\n")
+        for symbol in module_symbol_names:
+            file.write(f"\t&{symbol},\n")
+        file.write("\tNULL\n")
+        file.write("};\n")
 
 def generate_devicetree_h(filename: str):
     with open(filename, "w") as file:
@@ -258,17 +278,21 @@ def generate_devicetree_h(filename: str):
         extern "C" {
         #endif
         
+        // Array of device tree modules terminated with DTS_MODULE_TERMINATOR
         extern struct DtsDevice dts_devices[];
         
+        // Array of module symbols terminated with NULL
+        extern struct Module* dts_modules[];
+        
         #ifdef __cplusplus
         }
         #endif
         '''))
 
-def generate(output_path: str, items: list[object], bindings: list[Binding], verbose: bool):
+def generate(output_path: str, items: list[object], bindings: list[Binding], config, verbose: bool):
     if not os.path.exists(output_path):
         os.makedirs(output_path)
     devicetree_c_filename = os.path.join(output_path, "devicetree.c")
-    generate_devicetree_c(devicetree_c_filename, items, bindings, verbose)
+    generate_devicetree_c(devicetree_c_filename, items, bindings, config, verbose)
     devicetree_h_filename = os.path.join(output_path, "devicetree.h")
     generate_devicetree_h(devicetree_h_filename)

Buildscripts/DevicetreeCompiler/source/main.py

@@ -46,7 +46,7 @@ def main(config_path: str, output_path: str, verbose: bool) -> int:
         if verbose:
             for binding in bindings:
                 pprint(binding)
-        generate(output_path, transformed, bindings, verbose)
+        generate(output_path, transformed, bindings, config, verbose)
         return 0
     except DevicetreeException as caught:
         print("\033[31mError: ", caught, "\033[0m")