Restructure and move pins to generic linux

[Adafruit_Blinka-hackapet.git] / src / adafruit_blinka / microcontroller / generic_linux / lgpio_pin.py

diff --git a/src/adafruit_blinka/microcontroller/generic_linux/lgpio_pin.py b/src/adafruit_blinka/microcontroller/generic_linux/lgpio_pin.py
new file mode 100644 (file)
index 0000000..25a8268
--- /dev/null
+++ b/src/adafruit_blinka/microcontroller/generic_linux/lgpio_pin.py
@@ -0,0 +1,129 @@
+# SPDX-FileCopyrightText: 2025 Melissa LeBlanc-Williams for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+"""A Pin class for use with lgpio."""
+
+from pathlib import Path
+import lgpio
+
+
+def _get_gpiochip():
+    """
+    Determines the handle of the GPIO chip device to access.
+
+    iterate through sysfs  to find a GPIO chip device with a driver known to be
+    used for userspace GPIO access.
+    """
+    for dev in Path("/sys/bus/gpio/devices").glob("gpiochip*"):
+        drivers = set((dev / "of_node/compatible").read_text().split("\0"))
+        #   check if driver names are intended for userspace control
+        if drivers & {
+            "raspberrypi,rp1-gpio",
+            "raspberrypi,bcm2835-gpio",
+            "raspberrypi,bcm2711-gpio",
+        }:
+            return lgpio.gpiochip_open(int(dev.name[-1]))
+    # return chip0 as a fallback
+    return lgpio.gpiochip_open(0)
+
+
+CHIP = _get_gpiochip()
+
+
+class Pin:
+    """Pins dont exist in CPython so...lets make our own!"""
+
+    LOW = 0
+    HIGH = 1
+    OFF = LOW
+    ON = HIGH
+
+    # values of lg mode constants
+    PULL_NONE = 0x80
+    PULL_UP = 0x20
+    PULL_DOWN = 0x40
+    ACTIVE_LOW = 0x02
+
+    # drive mode lg constants
+    OPEN_DRAIN = 0x04
+    IN = 0x0100
+    OUT = 0x0200
+
+    # LG mode constants
+    _LG_ALERT = 0x400
+    _LG_GROUP = 0x800
+    _LG_MODES = IN | OUT | _LG_ALERT | _LG_GROUP
+    _LG_PULLS = PULL_NONE | PULL_UP | PULL_NONE | ACTIVE_LOW
+    _LG_DRIVES = OPEN_DRAIN
+
+    id = None
+    _value = LOW
+    _mode = IN
+
+    # we want exceptions
+    lgpio.exceptions = True
+
+    def __init__(self, bcm_number):
+        self.id = bcm_number
+
+    def __repr__(self):
+        return str(self.id)
+
+    def __eq__(self, other):
+        return self.id == other
+
+    def init(self, mode=IN, pull=None):
+        """Initialize the Pin"""
+        if mode is not None:
+            if mode == Pin.IN:
+                self._mode = Pin.IN
+                self._set_gpio_mode_in()
+            elif mode == self.OUT:
+                self._mode = Pin.OUT
+                Pin._check_result(lgpio.gpio_claim_output(CHIP, self.id, Pin.LOW))
+            else:
+                raise RuntimeError(f"Invalid mode for pin: {self.id}")
+        if pull is not None:
+            if self._mode != Pin.IN:
+                raise RuntimeError("Can only set pull resistor on input")
+            if pull in {Pin.PULL_UP, Pin.PULL_DOWN, Pin.PULL_NONE}:
+                self._set_gpio_mode_in(lflags=pull)
+            else:
+                raise RuntimeError(f"Invalid pull for pin: {self.id}")
+
+    def value(self, val=None):
+        """Set or return the Pin Value"""
+        if val is not None:
+            if val == Pin.LOW:
+                self._value = val
+                Pin._check_result(lgpio.gpio_write(CHIP, self.id, val))
+            elif val == Pin.HIGH:
+                self._value = val
+                Pin._check_result(lgpio.gpio_write(CHIP, self.id, val))
+            else:
+                raise RuntimeError("Invalid value for pin")
+            return None
+        return Pin._check_result(lgpio.gpio_read(CHIP, self.id))
+
+    @staticmethod
+    def _check_result(result):
+        """
+        convert any result other than zero to a text message and pass it back
+        as a runtime exception.  Typical usage:  use the lgpio call as the
+        argument.
+        """
+        if result < 0:
+            raise RuntimeError(lgpio.error_text(result))
+        return result
+
+    def _set_gpio_mode_in(self, lflags=0):
+        """
+        claim a gpio as input, or modify the flags (PULL_UP, PULL_DOWN, ... )
+        """
+        # This gpio_free may seem redundant, but is required when
+        #  changing the line-flags of an already acquired input line
+        try:
+            lgpio.gpio_free(CHIP, self.id)
+        except lgpio.error:
+            pass
+        Pin._check_result(lgpio.gpio_claim_input(CHIP, self.id, lFlags=lflags))