watch for "add"/"remove" uevents instead of "bind"/"unbind"

Linux has a stub driver for GPIO devices (the ones on the GPIO bus, not
their parent devices!) but it only actually *binds* to it those devices
that don't have a firmware node attached. This means that in some cases,
a "dynamic" GPIO controller can remain unnoticed by the proxy.

This behavior is related to fw_devlink handling and - even if we changed
the kernel to bind all GPIO devices to the stub driver - a fix in this
program is easier to distribute than a kernel fix.

Since an *added* GPIO device is considered functional, even without
binding to the stub driver, we can rely on the "add"/"remove" uevent
pair when detecting when GPIO chips come and go.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

Author: Bartosz Golaszewski

gpiod-sysfs-proxy

@@ -624,9 +624,9 @@ class Root(Directory):
             return None
 
         try:
-            if action == "bind":
+            if action == "add":
                 self._add_chip(device)
-            elif action == "unbind":
+            elif action == "remove":
                 self._remove_chip(device)
         except OSError as ex:
             if ex.errno not in [errno.ENOENT, errno.ENODEV]: