Proof of Concept: Creating Python bindings for ectool.

Mentor: Carlos Fernandez

Steps to Run

1. Compile the C source code into a shared library:

   gcc -shared -o libdummy_ectool.so -fPIC dummy_ectool.c

2. Run the Python script:

   python3 fw-fanctrl.py

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Explanation of Files

fw-fanctrl.py

This is the Python main script that works with the dummy_ectool library. It does the following:

1. Declares functions to read and write the fan speed.
2. Declares a function to read the fan status.
3. Contains an example usage block that shows how to call the functions.

dummy_ectool.py

This Python script is a wrapper for the libdummy_ectool.so shared library, as it:

1. Loads the shared library using the ctypes module.
2. Specifies the C function signatures (i.e., argument types and return types).
3. Offers Python functions that invoke the respective C functions.

dummy_ectool.c

This is a C source file that performs the fan control logic, as it:

1. Declares functions to obtain and set the fan speed.
2. Declares a function to retrieve the fan status.
3. Utilizes a global variable to emulate the fan speed.

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How the Program Works

The dummy_ectool.c source file is compiled into a shared library (libdummy_ectool.so) with the gcc compiler. The flags:

• -shared: Instructs the compiler to produce a shared library.
• -fPIC: Produces position-independent code, which is necessary for shared libraries.

The dummy_ectool.py script imports the shared library with ctypes.CDLL() and declares the function signatures for the C functions. It also specifies argument types and return types.

The fw-fanctrl.py script loads the dummy_ectool module, allowing access to the C functions. The program follows through with testing:

1. Displays the fan status and current speed.
2. Sets the fan speed to 3000 RPM and displays the new fan status and speed.
3. Attempts to set the fan speed to 6000 RPM, causing an error due to the correct range being 0-5000 RPM. This step tests the error handling mechanism.

This is only a proof of concept, large scale implementation will follow through.