resource: matchedsysfsgpio: add udev matched gpios

Add a support gpio line for which the gpiochip is identified
by udev and pin number provided is local the identified gpiochip.

This is useful when there is several gpio controller and the order
in which the controller are probed is not predictable. An common
example are the GPIOs provided by some USB FTDI chips.

This resouce re-use most the support already done for SysfsGPIO.
The global gpio index is computed at runtime, based on the udev
properties of the matched gpiochip.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

Author: jbrun3t

doc/configuration.rst

@@ -539,6 +539,32 @@ Arguments:
 Used by:
   - `GpioDigitalOutputDriver`_
 
+MatchedSysfsGpio
+++++++++++++++++
+A MatchedSysfsGpio resource describes a GPIO line, like a SysfsGPIO.
+The gpiochip is identified by matching udev properties. This allows
+identification through hot-plugging or rebooting for controllers like
+USB based gpiochips.
+
+.. code-block:: yaml
+
+   MatchedSysfsGpio:
+     match:
+       '@SUBSYSTEM': 'usb'
+       '@ID_SERIAL_SHORT': 'D38EJ8LF'
+     pin: 0
+
+The example would search for a USB gpiochip with the key `ID_SERIAL_SHORT`
+and the value `D38EJ8LF` and use the pin 0 of this device.
+The `ID_SERIAL_SHORT` property is set by the usb_id builtin helper program.
+
+Arguments:
+  - match (dict): key and value pairs for a udev match, see `udev Matching`_
+  - pin (int): gpio pin number within the matched gpiochip.
+
+Used by:
+  - `GpioDigitalOutputDriver`_
+
 NetworkService
 ~~~~~~~~~~~~~~
 A :any:`NetworkService` describes a remote SSH connection.
@@ -2139,6 +2165,7 @@ While the driver automatically exports the GPIO, it does not configure it in any
 Binds to:
   gpio:
     - `SysfsGPIO`_
+    - `MatchedSysfsGPIO`_
     - NetworkSysfsGPIO
 
 Implements:

labgrid/remote/exporter.py

@@ -579,11 +579,13 @@ class GPIOSysFSExport(ResourceExport):
 
     def __attrs_post_init__(self):
         super().__attrs_post_init__()
-        local_cls_name = self.cls
-        self.data['cls'] = f"Network{self.cls}"
-        from ..resource import base
-        local_cls = getattr(base, local_cls_name)
-        self.local = local_cls(target=None, name=None, **self.local_params)
+        if self.cls == "SysfsGPIO":
+            from ..resource.base import SysfsGPIO
+            self.local = SysfsGPIO(target=None, name=None, **self.local_params)
+        elif self.cls == "MatchedSysfsGPIO":
+            from ..resource.udev import MatchedSysfsGPIO
+            self.local = MatchedSysfsGPIO(target=None, name=None, **self.local_params)
+        self.data['cls'] = "NetworkSysfsGPIO"
         self.export_path = Path(GPIOSysFSExport._gpio_sysfs_path_prefix,
                                 f'gpio{self.local.index}')
         self.system_exported = False
@@ -624,6 +626,7 @@ def _stop(self, start_params):
             unexport.write(str(index).encode('utf-8'))
 
 exports["SysfsGPIO"] = GPIOSysFSExport
+exports["MatchedSysfsGPIO"] = GPIOSysFSExport
 
 
 @attr.s

labgrid/resource/__init__.py

@@ -15,6 +15,7 @@
     HIDRelay,
     IMXUSBLoader,
     LXAUSBMux,
+    MatchedSysfsGPIO,
     MXSUSBLoader,
     RKUSBLoader,
     SiSPMPowerPort,

labgrid/resource/suggest.py

@@ -23,6 +23,7 @@
     HIDRelay,
     USBDebugger,
     USBPowerPort,
+    MatchedSysfsGPIO
 )
 from ..util import dump
 
@@ -56,6 +57,7 @@ def __init__(self, args):
         self.resources.append(HIDRelay(**args))
         self.resources.append(USBDebugger(**args))
         self.resources.append(USBPowerPort(**args, index=0))
+        self.resources.append(MatchedSysfsGPIO(**args, pin=0))
 
     def suggest_callback(self, resource, meta, suggestions):
         cls = type(resource).__name__
@@ -84,6 +86,8 @@ def suggest_callback(self, resource, meta, suggestions):
             ))
             if cls == 'USBPowerPort':
                 print('    index: ?')
+            if cls == 'MatchedSysfsGPIO':
+                print('    pin: ?')
         print("  ---")
         print()
 

labgrid/resource/udev.py

@@ -708,3 +708,32 @@ def filter_match(self, device):
             return False
 
         return super().filter_match(device)
+
+@target_factory.reg_resource
+@attr.s(eq=False)
+class MatchedSysfsGPIO(USBResource):
+    """The MatchedSysfsGPIO described a SysfsGPIO matched by Udev
+
+    Args:
+        pin (int): gpio pin number within the matched gpiochip."""
+    pin = attr.ib(default=None, validator=attr.validators.instance_of(int))
+    index = None
+
+    def __attrs_post_init__(self):
+        self.match['SUBSYSTEM'] = 'gpio'
+        super().__attrs_post_init__()
+
+    def filter_match(self, device):
+        # Filter out the char device
+        if device.properties.get('DEVNAME') is not None:
+            return False
+        return super().filter_match(device)
+
+    def update(self):
+        super().update()
+        if self.device is not None:
+            if self.pin >= int(self.read_attr('ngpio')):
+                raise ValueError("MatchedSysfsGPIO pin out of bound")
+            self.index = int(self.read_attr('base')) + self.pin
+        else:
+            self.index = None