drm/connector: Add a fwnode pointer to drm_connector and register with ACPI (v2)

[ Upstream commit 48c429c6d18db115c277b75000152d8fa4cd35d0 ]

Add a fwnode pointer to struct drm_connector and register an acpi_bus_type
for the connectors with the ACPI subsystem (when CONFIG_ACPI is enabled).

The adding of the fwnode pointer allows drivers to associate a fwnode
that represents a connector with that connector.

When the new fwnode pointer points to an ACPI-companion, then the new
acpi_bus_type will cause the ACPI subsys to bind the device instantiated
for the connector with the fwnode by calling acpi_bind_one(). This will
result in a firmware_node symlink under /sys/class/card#-<connecter-name>/
which helps to verify that the fwnode-s and connectors are properly
matched.

Changes in v2:
- Make drm_connector_cleanup() call fwnode_handle_put() on
  connector->fwnode and document this

Co-developed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://lore.kernel.org/r/20210817215201.795062-3-hdegoede@redhat.com
Stable-dep-of: 89434b069e46 ("usb: typec: altmodes/displayport: Signal hpd low when exiting mode")
Signed-off-by: Sasha Levin <sashal@kernel.org>

include/drm/drm_connector.h

@@ -1174,6 +1174,14 @@ struct drm_connector {
 	struct device *kdev;
 	/** @attr: sysfs attributes */
 	struct device_attribute *attr;
+	/**
+	 * @fwnode: associated fwnode supplied by platform firmware
+	 *
+	 * Drivers can set this to associate a fwnode with a connector, drivers
+	 * are expected to get a reference on the fwnode when setting this.
+	 * drm_connector_cleanup() will call fwnode_handle_put() on this.
+	 */
+	struct fwnode_handle *fwnode;
 
 	/**
 	 * @head: