Pure python way of getting and setting input_absinfo in linux kernel evdev devices https://python-evdev.readthedocs.io/en/latest/apidoc.html#evdev.device.InputDevice.absinfo

evdev_input_absinfo_ioctl.py

from ctypes import *
from fcntl import ioctl

# See ioctl.h of your architecture for appropriate constants here.
# This has been tested only on x86
_IOC_NRBITS = 8
_IOC_TYPEBITS = 8

_IOC_NRSHIFT = 0
_IOC_TYPESHIFT = _IOC_NRSHIFT + _IOC_NRBITS
_IOC_SIZESHIFT = _IOC_TYPESHIFT + _IOC_TYPEBITS


_IOC_NONE = 0
_IOC_WRITE = 1
_IOC_READ  = 2
_IOC_SIZEBITS = 14
_IOC_DIRBITS = 2

_IOC_DIRSHIFT = _IOC_SIZESHIFT + _IOC_SIZEBITS


def _IOC(dir_, type_, nr, size):
    return (
        c_int32(dir_ << _IOC_DIRSHIFT).value |
        c_int32(ord(type_) << _IOC_TYPESHIFT).value |
        c_int32(nr << _IOC_NRSHIFT).value |
        c_int32(size << _IOC_SIZESHIFT).value)


def _IOC_TYPECHECK(t):
    return sizeof(t)


def _IO(type_, nr):
    return _IOC(_IOC_NONE, type_, nr, 0)


def _IOW(type_, nr, size):
    return _IOC(_IOC_WRITE, type_, nr, _IOC_TYPECHECK(size))


def _IOR(type_, nr, size):
    return _IOC(_IOC_READ, type_, nr, _IOC_TYPECHECK(size))


def _IOWR(type_, nr, size):
    return _IOC(_IOC_READ | _IOC_WRITE, type_, nr, _IOC_TYPECHECK(size))


# linux/input.h
class input_absinfo(Structure):
    _fields_ = [
        ('value', c_int32),
        ('minimum', c_int32),
        ('maximum', c_int32),
        ('fuzz', c_int32),
        ('flat', c_int32),
        ('resolution', c_int32)
    ]

    def __repr__(self):
        return "input_absinfo(value={}, minimum={}, maximum={}, fuzz={}, flat={} resolution={}) # object at {}".format(
            self.value, self.minimum, self.maximum, self.fuzz, self.flat, self.resolution, hex(id(self))
        )

# linux/input.h
def EVIOCGABS(abs):
    # EVIOCGABS(abs)		_IOR('E', 0x40 + (abs), struct input_absinfo)	/* get abs value/limits */
    return _IOR("E", 0x40 + abs, input_absinfo)

# linux/input.h
def EVIOCSABS(abs):
    # EVIOCSABS(abs)		_IOW('E', 0xc0 + (abs), struct input_absinfo)	/* set abs value/limits */
    return _IOW("E", 0xc0 + abs, input_absinfo)


def get_absinfo(fd, abs):
    absinfo = input_absinfo()
    r = ioctl(fd, EVIOCGABS(abs), absinfo)
    return r, absinfo


def set_absinfo(fd, abs, absinfo):
    r = ioctl(fd, EVIOCSABS(abs), absinfo)
    return r


if __name__ == '__main__':
    f = open("/dev/input/event5", 'rb')
    fd = f.fileno()

    # set first 4 axes absinfo
    for abs in range(4):
        r, absinfo = get_absinfo(fd, abs)
        if r!=0:
            print("error: get_absinfo ret = ", r)
        print("cur", absinfo)
        absinfo = input_absinfo()
        absinfo.minimum = 450
        absinfo.maximum = 3650
        absinfo.fuzz = 15
        absinfo.flat = 255
        print("set", absinfo)
        r = 0#set_absinfo(fd, abs, absinfo)
        if r == 0:
            print("OK")
        else:
            print("error: set_absinfo ret =", r)