Create stepper_motor driver class

[jilaypandya]

Problem Description

Problem Statement

The original stepper driver class was split into two driver classes namely stepper_driver_api (stepper motor motion control APIs)and stepper_drv_driver_api (stepper motor driver APIs) in #91979, leading to two similiar sounding driver classes in stepper.h.

Couple of issues which have been noted after the split w.r.t code structure are:

1. We have now two driver classes in stepper.h.
2. stepper_driver_api and stepper_drv_driver_api sound pretty similiar & can be confusing.
3. TMC5XXX devices are modeled as MFDs but are not structured accordingly, in contrast to other MFDs.

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Why was the API Split necessary?

Fig 1: Depiction of different combinations of stepper motion control and stepper_driverdevices.

Fig 2: TMC429 Application example using Step/Dir driver interface

The images above show that stepper motion controller and stepper driver are actually two seperate devices.

Proposed Change (Summary)

Split stepper.h in

include/zephyr/drivers
|_____ stepper.h (for stepper drivers only)
|_____ stepper_motor.h (for stepper motor motion controller driver only)

Split stepper_motor_drivers and stepper_drivers in:

drivers/
|_____ stepper/ (for stepper drivers only)
|_____ stepper_motor/ (for stepper motor motion controller driver only)

Proposed Change (Detailed)

Step 1: (achieveable till 4.4)
Linked PR: #101001

1. Rename stepper_driver_api --> stepper_motor_driver_api.
2. Rename stepper_drv_driver_api --> stepper_driver_api.
3. Create a new header file called stepper_motor.h in drivers.
   include/zephyr/drivers
   |_____ stepper.h (for stepper drivers only)
   |_____ stepper_motor.h (for stepper motor motion controller driver only)

Step 1.1: (achieveable till 4.4)

1. Split stepper_shell in stepper_motor_shell and stepper_shell

Step 2: (~ achieveable till 4.4) (latest by 4.5)

1. Refactor stepper motor drivers in stepper_motor/ under:
   Note: stepper_motor_driver_apiwill scale to motor_driver_api over time.

drivers/
|_____ stepper/ (for stepper drivers only)
|_____ stepper_motor/ (for stepper motor motion controller driver only)

2. TMC5XXX devices are to be restructured as:

mfd
|_____ mfd_tmc50xx.c
stepper
|_____ tmc50xx_stepper_driver.c
stepper_motor
|_____ tmc50xx_stepper_motor.c

Dependencies

None that I can think of at the moment.

Concerns and Unresolved Questions

How would the versioning of the new driver api class look like?

• unstable, since 4.0 ? These APIs have been there since 4.0 are now named differently.

Alternatives Considered

Linked PR: #101120

• Replace _drv from stepper_drv_driver_api with _amp, resulting in stepper_amp_driver_api and place the new stepper_amp_driver_api class as:

include/zephyr/drivers
|_____ stepper/stepper_amp.h (for stepper drivers only)
|_____ stepper.h (for stepper motor driver only)