Update pin.py

lgpio native changes

Author: frank-pet

src/adafruit_blinka/microcontroller/bcm283x/pin.py

@@ -2,29 +2,65 @@
 #
 # SPDX-License-Identifier: MIT
 """Broadcom BCM283x pin names"""
-from RPi import GPIO
+from pathlib import Path
+import lgpio
 
-GPIO.setmode(GPIO.BCM)  # Use BCM pins D4 = GPIO #4
-GPIO.setwarnings(False)  # shh!
+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!"""
 
-    IN = 0
-    OUT = 1
     LOW = 0
     HIGH = 1
-    PULL_NONE = 0
-    PULL_UP = 1
-    PULL_DOWN = 2
+    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
+        self.id = bcm_number              # pylint: disable=invalid-name
 
     def __repr__(self):
         return str(self.id)
@@ -35,40 +71,61 @@ def __eq__(self, other):
     def init(self, mode=IN, pull=None):
         """Initialize the Pin"""
         if mode is not None:
-            if mode == self.IN:
-                self._mode = self.IN
-                GPIO.setup(self.id, GPIO.IN)
+            if mode == Pin.IN:
+                self._mode = Pin.IN
+                self._set_gpio_mode_in()
             elif mode == self.OUT:
-                self._mode = self.OUT
-                GPIO.setup(self.id, GPIO.OUT)
+                self._mode = Pin.OUT
+                Pin._check_result(lgpio.gpio_claim_output(CHIP, self.id,
+                                  Pin.LOW))
             else:
-                raise RuntimeError("Invalid mode for pin: %s" % self.id)
+                raise RuntimeError(f"Invalid mode for pin: {self.id}")
         if pull is not None:
-            if self._mode != self.IN:
-                raise RuntimeError("Cannot set pull resistor on output")
-            if pull == self.PULL_UP:
-                GPIO.setup(self.id, GPIO.IN, pull_up_down=GPIO.PUD_UP)
-            elif pull == self.PULL_DOWN:
-                GPIO.setup(self.id, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
+            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("Invalid pull for pin: %s" % self.id)
+                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 == self.LOW:
+            if val == Pin.LOW:
                 self._value = val
-                GPIO.output(self.id, val)
-            elif val == self.HIGH:
+                Pin._check_result(lgpio.gpio_write(CHIP, self.id, val))
+            elif val == Pin.HIGH:
                 self._value = val
-                GPIO.output(self.id, val)
+                Pin._check_result(lgpio.gpio_write(CHIP, self.id, val))
             else:
                 raise RuntimeError("Invalid value for pin")
             return None
-        return GPIO.input(self.id)
+        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))
 
 
-# Pi 1B rev1 only?
 D0 = Pin(0)
 D1 = Pin(1)