protocol/driver: add DigitalInputProtocol, GpioDigitalInputDriver

this adds a new protocol `DigitalInputProtocol` and a GPIO driver
that implements it.

The `DigitalOutputProtocol` ABC now also inherits it, ensuring it can be
used in all existing driver implementations.

Additionally the client now automatically uses `DigitalInputProtocol`
when the command is `io get`.

By seperating the input from output protocol it is possible
to make sure the GPIO line is configured in direction `input` in sysfs,
which avoids shorts when reading out digital states  from DUT's.
Otherwise, one would have to rely on the circuitry of the GPIO line.

doc/configuration.rst

@@ -2174,9 +2174,33 @@ Implements:
 Arguments:
   - delay (float, default=2.0): delay in seconds between off and on
 
+GpioDigitalInputDriver
+~~~~~~~~~~~~~~~~~~~~~~
+The :any:`GpioDigitalInputDriver` reads a digital signal from a GPIO line.
+
+This driver configures GPIO lines via `the sysfs kernel interface <https://www.kernel.org/doc/html/latest/gpio/sysfs.html>`
+as an input.
+
+
+Binds to:
+  gpio:
+    - `SysfsGPIO`_
+    - `MatchedSysfsGPIO`_
+    - NetworkSysfsGPIO
+
+Implements:
+  - :any:`DigitalInputProtocol`
+
+.. code-block:: yaml
+
+   GpioDigitalInputDriver: {}
+
+Arguments:
+  - None
+
 GpioDigitalOutputDriver
 ~~~~~~~~~~~~~~~~~~~~~~~
-The :any:`GpioDigitalOutputDriver` writes a digital signal to a GPIO line.
+The :any:`GpioDigitalOutputDriver` reads and writes a digital signal from and to a GPIO line.
 
 This driver configures GPIO lines via `the sysfs kernel interface <https://www.kernel.org/doc/html/latest/gpio/sysfs.html>`.
 While the driver automatically exports the GPIO, it does not configure it in any other way than as an output.

labgrid/driver/__init__.py

@@ -26,7 +26,7 @@
 from .sigrokdriver import SigrokDriver, SigrokPowerDriver, SigrokDmmDriver
 from .usbstoragedriver import USBStorageDriver, NetworkUSBStorageDriver, Mode
 from .resetdriver import DigitalOutputResetDriver
-from .gpiodriver import GpioDigitalOutputDriver
+from .gpiodriver import GpioDigitalInputDriver, GpioDigitalOutputDriver
 from .filedigitaloutput import FileDigitalOutputDriver
 from .serialdigitaloutput import SerialPortDigitalOutputDriver
 from .xenadriver import XenaDriver

labgrid/driver/gpiodriver.py

@@ -2,13 +2,44 @@
 import attr
 
 from ..factory import target_factory
-from ..protocol import DigitalOutputProtocol
+from ..protocol import DigitalInputProtocol, DigitalOutputProtocol
 from ..resource.remote import NetworkSysfsGPIO
 from ..step import step
 from .common import Driver
 from ..util.agentwrapper import AgentWrapper
 
 
+@target_factory.reg_driver
+@attr.s(eq=False)
+class GpioDigitalInputDriver(Driver, DigitalInputProtocol):
+
+    bindings = {
+        "gpio": {"SysfsGPIO", "NetworkSysfsGPIO"},
+    }
+
+    def __attrs_post_init__(self):
+        super().__attrs_post_init__()
+        self.wrapper = None
+
+    def on_activate(self):
+        if isinstance(self.gpio, NetworkSysfsGPIO):
+            host = self.gpio.host
+        else:
+            host = None
+        self.wrapper = AgentWrapper(host)
+        self.proxy = self.wrapper.load('sysfsgpioin')
+
+    def on_deactivate(self):
+        self.wrapper.close()
+        self.wrapper = None
+        self.proxy = None
+
+    @Driver.check_active
+    @step(result=True)
+    def get(self):
+        return self.proxy.get(self.gpio.index)
+
+
 @target_factory.reg_driver
 @attr.s(eq=False)
 class GpioDigitalOutputDriver(Driver, DigitalOutputProtocol):

labgrid/protocol/__init__.py

@@ -6,6 +6,7 @@
 from .filetransferprotocol import FileTransferProtocol
 from .infoprotocol import InfoProtocol
 from .digitaloutputprotocol import DigitalOutputProtocol
+from .digitalinputprotocol import DigitalInputProtocol
 from .mmioprotocol import MMIOProtocol
 from .filesystemprotocol import FileSystemProtocol
 from .resetprotocol import ResetProtocol

labgrid/protocol/digitalinputprotocol.py

@@ -0,0 +1,10 @@
+import abc
+
+
+class DigitalInputProtocol(abc.ABC):
+    """Abstract class providing the DigitalInputProtocol interface"""
+
+    @abc.abstractmethod
+    def get(self):
+        """Implementations should return the status of the digital input."""
+        raise NotImplementedError

labgrid/protocol/digitaloutputprotocol.py

@@ -1,13 +1,10 @@
 import abc
+from .digitalinputprotocol import DigitalInputProtocol
 
 
-class DigitalOutputProtocol(abc.ABC):
-    """Abstract class providing the DigitalOutputProtocol interface"""
-
-    @abc.abstractmethod
-    def get(self):
-        """Implementations should return the status of the digital output."""
-        raise NotImplementedError
+class DigitalOutputProtocol(DigitalInputProtocol):
+    """Abstract class providing the DigitalOutputProtocol interface.
+    Implies that the set output can be read as well, so requires DigitalInputProtocol"""
 
     @abc.abstractmethod
     def set(self, status):

labgrid/remote/client.py

@@ -770,36 +770,63 @@ def digital_io(self):
         from ..resource import ModbusTCPCoil, OneWirePIO, HttpDigitalOutput
         from ..resource.remote import NetworkDeditecRelais8, NetworkSysfsGPIO, NetworkLXAIOBusPIO, NetworkHIDRelay
 
-        drv = None
-        try:
-            drv = target.get_driver("DigitalOutputProtocol", name=name)
-        except NoDriverFoundError:
-            for resource in target.resources:
-                if isinstance(resource, ModbusTCPCoil):
-                    drv = self._get_driver_or_new(target, "ModbusCoilDriver", name=name)
-                elif isinstance(resource, OneWirePIO):
-                    drv = self._get_driver_or_new(target, "OneWirePIODriver", name=name)
-                elif isinstance(resource, HttpDigitalOutput):
-                    drv = self._get_driver_or_new(target, "HttpDigitalOutputDriver", name=name)
-                elif isinstance(resource, NetworkDeditecRelais8):
-                    drv = self._get_driver_or_new(target, "DeditecRelaisDriver", name=name)
-                elif isinstance(resource, NetworkSysfsGPIO):
-                    drv = self._get_driver_or_new(target, "GpioDigitalOutputDriver", name=name)
-                elif isinstance(resource, NetworkLXAIOBusPIO):
-                    drv = self._get_driver_or_new(target, "LXAIOBusPIODriver", name=name)
-                elif isinstance(resource, NetworkHIDRelay):
-                    drv = self._get_driver_or_new(target, "HIDRelayDriver", name=name)
-                if drv:
-                    break
-
-        if not drv:
-            raise UserError("target has no compatible resource available")
         if action == "get":
+            drv = None
+            try:
+                drv = target.get_driver("DigitalInputProtocol", name=name)
+            except NoDriverFoundError:
+                for resource in target.resources:
+                    if isinstance(resource, ModbusTCPCoil):
+                        drv = self._get_driver_or_new(target, "ModbusCoilDriver", name=name)
+                    elif isinstance(resource, OneWirePIO):
+                        drv = self._get_driver_or_new(target, "OneWirePIODriver", name=name)
+                    elif isinstance(resource, HttpDigitalOutput):
+                        drv = self._get_driver_or_new(target, "HttpDigitalOutputDriver", name=name)
+                    elif isinstance(resource, NetworkDeditecRelais8):
+                        drv = self._get_driver_or_new(target, "DeditecRelaisDriver", name=name)
+                    elif isinstance(resource, NetworkSysfsGPIO):
+                        drv = self._get_driver_or_new(target, "GpioDigitalInputDriver", name=name)
+                    elif isinstance(resource, NetworkLXAIOBusPIO):
+                        drv = self._get_driver_or_new(target, "LXAIOBusPIODriver", name=name)
+                    elif isinstance(resource, NetworkHIDRelay):
+                        drv = self._get_driver_or_new(target, "HIDRelayDriver", name=name)
+                    if drv:
+                        break
+
+            if not drv:
+                raise UserError("target has no compatible resource available")
+
             print(f"digital IO{' ' + name if name else ''} for place {place.name} is {'high' if drv.get() else 'low'}")
-        elif action == "high":
-            drv.set(True)
-        elif action == "low":
-            drv.set(False)
+        else:
+            drv = None
+            try:
+                drv = target.get_driver("DigitalOutputProtocol", name=name)
+            except NoDriverFoundError:
+                for resource in target.resources:
+                    if isinstance(resource, ModbusTCPCoil):
+                        drv = self._get_driver_or_new(target, "ModbusCoilDriver", name=name)
+                    elif isinstance(resource, OneWirePIO):
+                        drv = self._get_driver_or_new(target, "OneWirePIODriver", name=name)
+                    elif isinstance(resource, HttpDigitalOutput):
+                        drv = self._get_driver_or_new(target, "HttpDigitalOutputDriver", name=name)
+                    elif isinstance(resource, NetworkDeditecRelais8):
+                        drv = self._get_driver_or_new(target, "DeditecRelaisDriver", name=name)
+                    elif isinstance(resource, NetworkSysfsGPIO):
+                        drv = self._get_driver_or_new(target, "GpioDigitalOutputDriver", name=name)
+                    elif isinstance(resource, NetworkLXAIOBusPIO):
+                        drv = self._get_driver_or_new(target, "LXAIOBusPIODriver", name=name)
+                    elif isinstance(resource, NetworkHIDRelay):
+                        drv = self._get_driver_or_new(target, "HIDRelayDriver", name=name)
+                    if drv:
+                        break
+
+            if not drv:
+                raise UserError("target has no compatible resource available")
+
+            if action == "high":
+                drv.set(True)
+            elif action == "low":
+                drv.set(False)
 
     async def _console(self, place, target, timeout, *, logfile=None, loop=False, listen_only=False):
         name = self.args.name

labgrid/util/agents/sysfsgpioin.py

@@ -0,0 +1,72 @@
+"""
+This module implements reading GPIOs via sysfs GPIO kernel interface.
+
+Takes an integer property 'index' which refers to the already exported GPIO device.
+
+"""
+import logging
+import os
+
+class GpioDigitalInput:
+    _gpio_sysfs_path_prefix = '/sys/class/gpio'
+
+    @staticmethod
+    def _assert_gpio_line_is_exported(index):
+        gpio_sysfs_path = os.path.join(GpioDigitalInput._gpio_sysfs_path_prefix,
+                                       f'gpio{index}')
+        # Deprecated: the exporter can export on acquire, we are leaving this
+        # in for now to support exporters which have not been updated yet.
+        if not os.path.exists(gpio_sysfs_path):
+            export_sysfs_path = os.path.join(GpioDigitalInput._gpio_sysfs_path_prefix, 'export')
+            with open(export_sysfs_path, mode='wb') as export:
+                export.write(str(index).encode('utf-8'))
+        if not os.path.exists(gpio_sysfs_path):
+            raise ValueError("Device not found")
+
+    def __init__(self, index):
+        self._logger = logging.getLogger("Device: ")
+        GpioDigitalInput._assert_gpio_line_is_exported(index)
+        gpio_sysfs_path = os.path.join(GpioDigitalInput._gpio_sysfs_path_prefix,
+                                       f'gpio{index}')
+
+        gpio_sysfs_direction_path = os.path.join(gpio_sysfs_path, 'direction')
+        with open(gpio_sysfs_direction_path, 'rb') as direction_fd:
+            literal_value = direction_fd.read(2)
+        if literal_value != b"in":
+            self._logger.debug("Configuring GPIO %d as input.", index)
+            with open(gpio_sysfs_direction_path, 'wb') as direction_fd:
+                direction_fd.write(b'in')
+
+        gpio_sysfs_value_path = os.path.join(gpio_sysfs_path, 'value')
+        self.gpio_sysfs_value_fd = os.open(gpio_sysfs_value_path, flags=(os.O_RDONLY | os.O_SYNC))
+
+    def __del__(self):
+        os.close(self.gpio_sysfs_value_fd)
+        self.gpio_sysfs_value_fd = None
+
+    def get(self):
+        os.lseek(self.gpio_sysfs_value_fd, 0, os.SEEK_SET)
+        literal_value = os.read(self.gpio_sysfs_value_fd, 1)
+        if literal_value == b'0':
+            return False
+        elif literal_value == b'1':
+            return True
+        raise ValueError("GPIO value is out of range.")
+
+
+_gpios = {}
+
+def _get_gpio_line(index):
+    if index not in _gpios:
+        _gpios[index] = GpioDigitalInput(index=index)
+    return _gpios[index]
+
+
+def handle_get(index):
+    gpio_line = _get_gpio_line(index)
+    return gpio_line.get()
+
+
+methods = {
+    'get': handle_get,
+}

tests/test_agent.py

@@ -106,6 +106,9 @@ def test_all_modules():
     methods = aw.list()
     assert 'sysfsgpio.set' in methods
     assert 'sysfsgpio.get' in methods
+    aw.load('sysfsgpioin')
+    methods = aw.list()
+    assert 'sysfsgpio.get' in methods
     aw.load('usb_hid_relay')
     methods = aw.list()
     assert 'usb_hid_relay.set' in methods