Request for comments on: adding the Linux Motion Control subsystem to the kernel. The Linux Motion Control subsystem (LMC) is a new kernel subsystem and associated device drivers for hardware devices that control mechanical motion. Most often these are different types of motors, but can also be linear actuators for example. This subsystem defines a new UAPI for motion devices on the user-space side, as well as common functionality for hardware device drivers on the driver side. The UAPI is based on a ioctl() interface on character devices representing a specific hardware device. The hardware device can control one or more actuators (motors), which are identified as channels in the UAPI. It is possible to execute motions on individual channels, or combined affecting several selected (or all) channels simutaneously. Examples of coordinated movements of several channels could be the individual axes of a 3D printer or CNC machine for example. On the hardware side, this initial set of patches also includes two drivers for two different kinds of motors. One is a stepper motor controller device that containes a ramp generator capable of autonomously executing controlled motions following a multi-point acceleration profile (TMC5240), as well as a simple DC motor controller driver that can control DC motors via a half-bridge or full H-bridge driver such as the TI DRV8873 for example. Towards the IIO subsystem, LMC supports generating iio trigger events that fire at certain motion events, such as passing a pre-programmed position or when reaching the motion target position, depending on the capabilities of the hardware device. This enables for example triggering an ADC measurement at a certain position during a movement. In the future, making use of PREEMPT_RT, even dumb STEP/DIR type stepper motor controller drivers may be implemented entirely in the kernel, depending on some characteristics of the hardware (latency jittter, interrupt latency and CPU speed mainly). The existence of this subsystem may affect other projects, such as Linux-CNC and Klipper for example. This code is already in use controlling machines with up to 16 stepper motors and up to 4 DC motors simutaneously. Up to this point the UAPI has shown to be adequate and sufficient. Careful thought has gone into the UAPI design to make sure it coveres as many use-cases as possible, while being versioned and extensible in the future, with backwards compatibility in mind. David Jander (7): drivers: Add motion control subsystem motion: Add ADI/Trinamic TMC5240 stepper motor controller motion: Add simple-pwm.c PWM based DC motor controller driver Documentation: Add Linux Motion Control documentation dt-bindings: motion: Add common motion device properties dt-bindings: motion: Add adi,tmc5240 bindings dt-bindings: motion: Add motion-simple-pwm bindings .../bindings/motion/adi,tmc5240.yaml | 60 + .../devicetree/bindings/motion/common.yaml | 52 + .../bindings/motion/motion-simple-pwm.yaml | 55 + Documentation/motion/index.rst | 18 + Documentation/motion/motion-uapi.rst | 555 ++++++++ Documentation/subsystem-apis.rst | 1 + MAINTAINERS | 13 + drivers/Kconfig | 2 + drivers/Makefile | 2 + drivers/motion/Kconfig | 42 + drivers/motion/Makefile | 5 + drivers/motion/motion-core.c | 823 ++++++++++++ drivers/motion/motion-core.h | 172 +++ drivers/motion/motion-helpers.c | 590 +++++++++ drivers/motion/motion-helpers.h | 23 + drivers/motion/simple-pwm.c | 199 +++ drivers/motion/tmc5240.c | 1157 +++++++++++++++++ include/uapi/linux/motion.h | 229 ++++ 18 files changed, 3998 insertions(+) create mode 100644 Documentation/devicetree/bindings/motion/adi,tmc5240.yaml create mode 100644 Documentation/devicetree/bindings/motion/common.yaml create mode 100644 Documentation/devicetree/bindings/motion/motion-simple-pwm.yaml create mode 100644 Documentation/motion/index.rst create mode 100644 Documentation/motion/motion-uapi.rst create mode 100644 drivers/motion/Kconfig create mode 100644 drivers/motion/Makefile create mode 100644 drivers/motion/motion-core.c create mode 100644 drivers/motion/motion-core.h create mode 100644 drivers/motion/motion-helpers.c create mode 100644 drivers/motion/motion-helpers.h create mode 100644 drivers/motion/simple-pwm.c create mode 100644 drivers/motion/tmc5240.c create mode 100644 include/uapi/linux/motion.h -- 2.47.2
