python-cc1101/cc1101/_gpio.py

import pathlib
import typing

ChipSelector = typing.Union[pathlib.Path, str, int]


def _format_chip_selector(selector: ChipSelector) -> str:
    if isinstance(selector, int):
        return "/dev/gpiochip{}".format(selector)
    return str(selector)


def get_line(chip_selector: ChipSelector, line_name: str) -> "gpiod.line":  # type: ignore
    # lazy import to protect stable API against incompatilibities in hhk7734/python3-gpiod
    # e.g., incompatibility of v1.5.0 with python3.5&3.6 (python_requires not set)
    import gpiod  # pylint: disable=import-outside-toplevel

    try:
        chip = gpiod.chip(chip_selector)
    except PermissionError as exc:
        raise PermissionError(
            "Failed to access GPIO chip {}.".format(
                _format_chip_selector(chip_selector)
            )
            + "\nVerify that the current user has read and write access."
            + "\nOn some systems, like Raspberry Pi OS / Raspbian,"
            + "\n\tsudo usermod -a -G gpio $USER"
            + "\nfollowed by a re-login grants sufficient permissions."
        ) from exc
    except (FileNotFoundError, OSError, TypeError) as exc:
        raise FileNotFoundError(
            "Failed to find GPIO chip {}.".format(_format_chip_selector(chip_selector))
            + "\nRun command `gpiodetect` or `gpioinfo` to view available GPIO chips."
        ) from exc
    line = chip.find_line(name=line_name)
    try:
        line.name
    except RuntimeError as exc:
        raise ValueError(
            "Failed to find GPIO line with name {!r}.".format(line_name)
            + "\nRun command `gpioinfo` to view the names of all available GPIO lines."
        ) from exc
    return line