@@ -12,6 +12,15 @@ config DRM_PANEL_BRIDGE
help
DRM bridge wrapper of DRM panels
+config DRM_AUX_BRIDGE
+ tristate
+ depends on DRM_BRIDGE && OF
+ select AUXILIARY_BUS
+ select DRM_PANEL_BRIDGE
+ help
+ Simple transparent bridge that is used by several non-DRM drivers to
+ build bridges chain.
+
menu "Display Interface Bridges"
depends on DRM && DRM_BRIDGE
@@ -1,4 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_DRM_AUX_BRIDGE) += aux-bridge.o
obj-$(CONFIG_DRM_CHIPONE_ICN6211) += chipone-icn6211.o
obj-$(CONFIG_DRM_CHRONTEL_CH7033) += chrontel-ch7033.o
obj-$(CONFIG_DRM_CROS_EC_ANX7688) += cros-ec-anx7688.o
new file mode 100644
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2023 Linaro Ltd.
+ *
+ * Author: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
+ */
+#include <linux/auxiliary_bus.h>
+#include <linux/module.h>
+
+#include <drm/drm_bridge.h>
+#include <drm/bridge/aux-bridge.h>
+
+static DEFINE_IDA(drm_aux_bridge_ida);
+
+static void drm_aux_bridge_release(struct device *dev)
+{
+ struct auxiliary_device *adev = to_auxiliary_dev(dev);
+
+ ida_free(&drm_aux_bridge_ida, adev->id);
+
+ kfree(adev);
+}
+
+static void drm_aux_bridge_unregister_adev(void *_adev)
+{
+ struct auxiliary_device *adev = _adev;
+
+ auxiliary_device_delete(adev);
+ auxiliary_device_uninit(adev);
+}
+
+/**
+ * drm_aux_bridge_register - Create a simple bridge device to link the chain
+ * @parent: device instance providing this bridge
+ *
+ * Creates a simple DRM bridge that doesn't implement any drm_bridge
+ * operations. Such bridges merely fill a place in the bridge chain linking
+ * surrounding DRM bridges.
+ *
+ * Return: zero on success, negative error code on failure
+ */
+int drm_aux_bridge_register(struct device *parent)
+{
+ struct auxiliary_device *adev;
+ int ret;
+
+ adev = kzalloc(sizeof(*adev), GFP_KERNEL);
+ if (!adev)
+ return -ENOMEM;
+
+ ret = ida_alloc(&drm_aux_bridge_ida, GFP_KERNEL);
+ if (ret < 0) {
+ kfree(adev);
+ return ret;
+ }
+
+ adev->id = ret;
+ adev->name = "aux_bridge";
+ adev->dev.parent = parent;
+ adev->dev.of_node = parent->of_node;
+ adev->dev.release = drm_aux_bridge_release;
+
+ ret = auxiliary_device_init(adev);
+ if (ret) {
+ ida_free(&drm_aux_bridge_ida, adev->id);
+ kfree(adev);
+ return ret;
+ }
+
+ ret = auxiliary_device_add(adev);
+ if (ret) {
+ auxiliary_device_uninit(adev);
+ return ret;
+ }
+
+ return devm_add_action_or_reset(parent, drm_aux_bridge_unregister_adev, adev);
+}
+EXPORT_SYMBOL_GPL(drm_aux_bridge_register);
+
+struct drm_aux_bridge_data {
+ struct drm_bridge bridge;
+ struct drm_bridge *next_bridge;
+ struct device *dev;
+};
+
+static int drm_aux_bridge_attach(struct drm_bridge *bridge,
+ enum drm_bridge_attach_flags flags)
+{
+ struct drm_aux_bridge_data *data;
+
+ if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
+ return -EINVAL;
+
+ data = container_of(bridge, struct drm_aux_bridge_data, bridge);
+
+ return drm_bridge_attach(bridge->encoder, data->next_bridge, bridge,
+ DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+}
+
+static const struct drm_bridge_funcs drm_aux_bridge_funcs = {
+ .attach = drm_aux_bridge_attach,
+};
+
+static int drm_aux_bridge_probe(struct auxiliary_device *auxdev,
+ const struct auxiliary_device_id *id)
+{
+ struct drm_aux_bridge_data *data;
+
+ data = devm_kzalloc(&auxdev->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->dev = &auxdev->dev;
+ data->next_bridge = devm_drm_of_get_bridge(&auxdev->dev, auxdev->dev.of_node, 0, 0);
+ if (IS_ERR(data->next_bridge))
+ return dev_err_probe(&auxdev->dev, PTR_ERR(data->next_bridge),
+ "failed to acquire drm_bridge\n");
+
+ data->bridge.funcs = &drm_aux_bridge_funcs;
+ data->bridge.of_node = data->dev->of_node;
+
+ return devm_drm_bridge_add(data->dev, &data->bridge);
+}
+
+static const struct auxiliary_device_id drm_aux_bridge_table[] = {
+ { .name = KBUILD_MODNAME ".aux_bridge" },
+ {},
+};
+MODULE_DEVICE_TABLE(auxiliary, drm_aux_bridge_table);
+
+static struct auxiliary_driver drm_aux_bridge_drv = {
+ .name = "aux_bridge",
+ .id_table = drm_aux_bridge_table,
+ .probe = drm_aux_bridge_probe,
+};
+module_auxiliary_driver(drm_aux_bridge_drv);
+
+MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>");
+MODULE_DESCRIPTION("DRM transparent bridge");
+MODULE_LICENSE("GPL");
new file mode 100644
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2023 Linaro Ltd.
+ *
+ * Author: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
+ */
+#ifndef DRM_AUX_BRIDGE_H
+#define DRM_AUX_BRIDGE_H
+
+#if IS_ENABLED(CONFIG_DRM_AUX_BRIDGE)
+int drm_aux_bridge_register(struct device *parent);
+#else
+static inline int drm_aux_bridge_register(struct device *parent)
+{
+ return 0;
+}
+#endif
+
+#endif