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.

Co-authored-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/gpu/drm/drm_sysfs.c | 37 +++++++++++++++++++++++++++++++++++++
 include/drm/drm_connector.h |  2 ++
 2 files changed, 39 insertions(+)

diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
index 553024bcda8a..12cc649c44f0 100644
--- a/drivers/gpu/drm/drm_sysfs.c
+++ b/drivers/gpu/drm/drm_sysfs.c
@@ -10,6 +10,7 @@
  * Copyright (c) 2003-2004 IBM Corp.
  */

+#include <linux/acpi.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/export.h>
@@ -56,6 +57,39 @@ static struct device_type drm_sysfs_device_connector = {

 struct class *drm_class;

+#ifdef CONFIG_ACPI
+static bool drm_connector_acpi_bus_match(struct device *dev)
+{
+       return dev->type == &drm_sysfs_device_connector;
+}
+
+static struct acpi_device *drm_connector_acpi_find_companion(struct device *dev)
+{
+       struct drm_connector *connector = to_drm_connector(dev);
+
+       return to_acpi_device_node(connector->fwnode);
+}
+
+static struct acpi_bus_type drm_connector_acpi_bus = {
+       .name = "drm_connector",
+       .match = drm_connector_acpi_bus_match,
+       .find_companion = drm_connector_acpi_find_companion,
+};
+
+static void drm_sysfs_acpi_register(void)
+{
+       register_acpi_bus_type(&drm_connector_acpi_bus);
+}
+
+static void drm_sysfs_acpi_unregister(void)
+{
+       unregister_acpi_bus_type(&drm_connector_acpi_bus);
+}
+#else
+static void drm_sysfs_acpi_register(void) { }
+static void drm_sysfs_acpi_unregister(void) { }
+#endif
+
 static char *drm_devnode(struct device *dev, umode_t *mode)
 {
        return kasprintf(GFP_KERNEL, "dri/%s", dev_name(dev));
@@ -89,6 +123,8 @@ int drm_sysfs_init(void)
        }

        drm_class->devnode = drm_devnode;
+
+       drm_sysfs_acpi_register();
        return 0;
 }

@@ -101,6 +137,7 @@ void drm_sysfs_destroy(void)
 {
        if (IS_ERR_OR_NULL(drm_class))
                return;
+       drm_sysfs_acpi_unregister();
        class_remove_file(drm_class, &class_attr_version.attr);
        class_destroy(drm_class);
        drm_class = NULL;
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 0261801af62c..d20bfd7576ed 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -1254,6 +1254,8 @@ struct drm_connector {
        struct device *kdev;
        /** @attr: sysfs attributes */
        struct device_attribute *attr;
+       /** @fwnode: associated fwnode supplied by platform firmware */
+       struct fwnode_handle *fwnode;

        /**
         * @head:
--
2.31.1