1 files changed, 379 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_bridge_connector.c b/drivers/gpu/drm/drm_bridge_connector.c
new file mode 100644
index 000000000000..c6994fe673f3
--- /dev/null
+++ b/drivers/gpu/drm/drm_bridge_connector.c
@@ -0,0 +1,379 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Laurent Pinchart <laurent.pinchart@ideasonboard.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_bridge.h>
+#include <drm/drm_bridge_connector.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_device.h>
+#include <drm/drm_edid.h>
+#include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_probe_helper.h>
+
+/**
+ * DOC: overview
+ *
+ * The DRM bridge connector helper object provides a DRM connector
+ * implementation that wraps a chain of &struct drm_bridge. The connector
+ * operations are fully implemented based on the operations of the bridges in
+ * the chain, and don't require any intervention from the display controller
+ * driver at runtime.
+ *
+ * To use the helper, display controller drivers create a bridge connector with
+ * a call to drm_bridge_connector_init(). This associates the newly created
+ * connector with the chain of bridges passed to the function and registers it
+ * with the DRM device. At that point the connector becomes fully usable, no
+ * further operation is needed.
+ *
+ * The DRM bridge connector operations are implemented based on the operations
+ * provided by the bridges in the chain. Each connector operation is delegated
+ * to the bridge closest to the connector (at the end of the chain) that
+ * provides the relevant functionality.
+ *
+ * To make use of this helper, all bridges in the chain shall report bridge
+ * operation flags (&drm_bridge->ops) and bridge output type
+ * (&drm_bridge->type), as well as the DRM_BRIDGE_ATTACH_NO_CONNECTOR attach
+ * flag (none of the bridges shall create a DRM connector directly).
+ */
+
+/**
+ * struct drm_bridge_connector - A connector backed by a chain of bridges
+ */
+struct drm_bridge_connector {
+	/**
+	 * @base: The base DRM connector
+	 */
+	struct drm_connector base;
+	/**
+	 * @encoder:
+	 *
+	 * The encoder at the start of the bridges chain.
+	 */
+	struct drm_encoder *encoder;
+	/**
+	 * @bridge_edid:
+	 *
+	 * The last bridge in the chain (closest to the connector) that provides
+	 * EDID read support, if any (see &DRM_BRIDGE_OP_EDID).
+	 */
+	struct drm_bridge *bridge_edid;
+	/**
+	 * @bridge_hpd:
+	 *
+	 * The last bridge in the chain (closest to the connector) that provides
+	 * hot-plug detection notification, if any (see &DRM_BRIDGE_OP_HPD).
+	 */
+	struct drm_bridge *bridge_hpd;
+	/**
+	 * @bridge_detect:
+	 *
+	 * The last bridge in the chain (closest to the connector) that provides
+	 * connector detection, if any (see &DRM_BRIDGE_OP_DETECT).
+	 */
+	struct drm_bridge *bridge_detect;
+	/**
+	 * @bridge_modes:
+	 *
+	 * The last bridge in the chain (closest to the connector) that provides
+	 * connector modes detection, if any (see &DRM_BRIDGE_OP_MODES).
+	 */
+	struct drm_bridge *bridge_modes;
+};
+
+#define to_drm_bridge_connector(x) \
+	container_of(x, struct drm_bridge_connector, base)
+
+/* -----------------------------------------------------------------------------
+ * Bridge Connector Hot-Plug Handling
+ */
+
+static void drm_bridge_connector_hpd_notify(struct drm_connector *connector,
+					    enum drm_connector_status status)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+	struct drm_bridge *bridge;
+
+	/* Notify all bridges in the pipeline of hotplug events. */
+	drm_for_each_bridge_in_chain(bridge_connector->encoder, bridge) {
+		if (bridge->funcs->hpd_notify)
+			bridge->funcs->hpd_notify(bridge, status);
+	}
+}
+
+static void drm_bridge_connector_hpd_cb(void *cb_data,
+					enum drm_connector_status status)
+{
+	struct drm_bridge_connector *drm_bridge_connector = cb_data;
+	struct drm_connector *connector = &drm_bridge_connector->base;
+	struct drm_device *dev = connector->dev;
+	enum drm_connector_status old_status;
+
+	mutex_lock(&dev->mode_config.mutex);
+	old_status = connector->status;
+	connector->status = status;
+	mutex_unlock(&dev->mode_config.mutex);
+
+	if (old_status == status)
+		return;
+
+	drm_bridge_connector_hpd_notify(connector, status);
+
+	drm_kms_helper_hotplug_event(dev);
+}
+
+/**
+ * drm_bridge_connector_enable_hpd - Enable hot-plug detection for the connector
+ * @connector: The DRM bridge connector
+ *
+ * This function enables hot-plug detection for the given bridge connector.
+ * This is typically used by display drivers in their resume handler.
+ */
+void drm_bridge_connector_enable_hpd(struct drm_connector *connector)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+	struct drm_bridge *hpd = bridge_connector->bridge_hpd;
+
+	if (hpd)
+		drm_bridge_hpd_enable(hpd, drm_bridge_connector_hpd_cb,
+				      bridge_connector);
+}
+EXPORT_SYMBOL_GPL(drm_bridge_connector_enable_hpd);
+
+/**
+ * drm_bridge_connector_disable_hpd - Disable hot-plug detection for the
+ * connector
+ * @connector: The DRM bridge connector
+ *
+ * This function disables hot-plug detection for the given bridge connector.
+ * This is typically used by display drivers in their suspend handler.
+ */
+void drm_bridge_connector_disable_hpd(struct drm_connector *connector)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+	struct drm_bridge *hpd = bridge_connector->bridge_hpd;
+
+	if (hpd)
+		drm_bridge_hpd_disable(hpd);
+}
+EXPORT_SYMBOL_GPL(drm_bridge_connector_disable_hpd);
+
+/* -----------------------------------------------------------------------------
+ * Bridge Connector Functions
+ */
+
+static enum drm_connector_status
+drm_bridge_connector_detect(struct drm_connector *connector, bool force)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+	struct drm_bridge *detect = bridge_connector->bridge_detect;
+	enum drm_connector_status status;
+
+	if (detect) {
+		status = detect->funcs->detect(detect);
+
+		drm_bridge_connector_hpd_notify(connector, status);
+	} else {
+		switch (connector->connector_type) {
+		case DRM_MODE_CONNECTOR_DPI:
+		case DRM_MODE_CONNECTOR_LVDS:
+		case DRM_MODE_CONNECTOR_DSI:
+			status = connector_status_connected;
+			break;
+		default:
+			status = connector_status_unknown;
+			break;
+		}
+	}
+
+	return status;
+}
+
+static void drm_bridge_connector_destroy(struct drm_connector *connector)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+
+	if (bridge_connector->bridge_hpd) {
+		struct drm_bridge *hpd = bridge_connector->bridge_hpd;
+
+		drm_bridge_hpd_disable(hpd);
+	}
+
+	drm_connector_unregister(connector);
+	drm_connector_cleanup(connector);
+
+	kfree(bridge_connector);
+}
+
+static const struct drm_connector_funcs drm_bridge_connector_funcs = {
+	.reset = drm_atomic_helper_connector_reset,
+	.detect = drm_bridge_connector_detect,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = drm_bridge_connector_destroy,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+/* -----------------------------------------------------------------------------
+ * Bridge Connector Helper Functions
+ */
+
+static int drm_bridge_connector_get_modes_edid(struct drm_connector *connector,
+					       struct drm_bridge *bridge)
+{
+	enum drm_connector_status status;
+	struct edid *edid;
+	int n;
+
+	status = drm_bridge_connector_detect(connector, false);
+	if (status != connector_status_connected)
+		goto no_edid;
+
+	edid = bridge->funcs->get_edid(bridge, connector);
+	if (!edid || !drm_edid_is_valid(edid)) {
+		kfree(edid);
+		goto no_edid;
+	}
+
+	drm_connector_update_edid_property(connector, edid);
+	n = drm_add_edid_modes(connector, edid);
+
+	kfree(edid);
+	return n;
+
+no_edid:
+	drm_connector_update_edid_property(connector, NULL);
+	return 0;
+}
+
+static int drm_bridge_connector_get_modes(struct drm_connector *connector)
+{
+	struct drm_bridge_connector *bridge_connector =
+		to_drm_bridge_connector(connector);
+	struct drm_bridge *bridge;
+
+	/*
+	 * If display exposes EDID, then we parse that in the normal way to
+	 * build table of supported modes.
+	 */
+	bridge = bridge_connector->bridge_edid;
+	if (bridge)
+		return drm_bridge_connector_get_modes_edid(connector, bridge);
+
+	/*
+	 * Otherwise if the display pipeline reports modes (e.g. with a fixed
+	 * resolution panel or an analog TV output), query it.
+	 */
+	bridge = bridge_connector->bridge_modes;
+	if (bridge)
+		return bridge->funcs->get_modes(bridge, connector);
+
+	/*
+	 * We can't retrieve modes, which can happen for instance for a DVI or
+	 * VGA output with the DDC bus unconnected. The KMS core will add the
+	 * default modes.
+	 */
+	return 0;
+}
+
+static const struct drm_connector_helper_funcs drm_bridge_connector_helper_funcs = {
+	.get_modes = drm_bridge_connector_get_modes,
+	/* No need for .mode_valid(), the bridges are checked by the core. */
+};
+
+/* -----------------------------------------------------------------------------
+ * Bridge Connector Initialisation
+ */
+
+/**
+ * drm_bridge_connector_init - Initialise a connector for a chain of bridges
+ * @drm: the DRM device
+ * @encoder: the encoder where the bridge chain starts
+ *
+ * Allocate, initialise and register a &drm_bridge_connector with the @drm
+ * device. The connector is associated with a chain of bridges that starts at
+ * the @encoder. All bridges in the chain shall report bridge operation flags
+ * (&drm_bridge->ops) and bridge output type (&drm_bridge->type), and none of
+ * them may create a DRM connector directly.
+ *
+ * Returns a pointer to the new connector on success, or a negative error
+ * pointer otherwise.
+ */
+struct drm_connector *drm_bridge_connector_init(struct drm_device *drm,
+						struct drm_encoder *encoder)
+{
+	struct drm_bridge_connector *bridge_connector;
+	struct drm_connector *connector;
+	struct i2c_adapter *ddc = NULL;
+	struct drm_bridge *bridge;
+	int connector_type;
+
+	bridge_connector = kzalloc(sizeof(*bridge_connector), GFP_KERNEL);
+	if (!bridge_connector)
+		return ERR_PTR(-ENOMEM);
+
+	bridge_connector->encoder = encoder;
+
+	/*
+	 * TODO: Handle doublescan_allowed, stereo_allowed and
+	 * ycbcr_420_allowed.
+	 */
+	connector = &bridge_connector->base;
+	connector->interlace_allowed = true;
+
+	/*
+	 * Initialise connector status handling. First locate the furthest
+	 * bridges in the pipeline that support HPD and output detection. Then
+	 * initialise the connector polling mode, using HPD if available and
+	 * falling back to polling if supported. If neither HPD nor output
+	 * detection are available, we don't support hotplug detection at all.
+	 */
+	connector_type = DRM_MODE_CONNECTOR_Unknown;
+	drm_for_each_bridge_in_chain(encoder, bridge) {
+		if (!bridge->interlace_allowed)
+			connector->interlace_allowed = false;
+
+		if (bridge->ops & DRM_BRIDGE_OP_EDID)
+			bridge_connector->bridge_edid = bridge;
+		if (bridge->ops & DRM_BRIDGE_OP_HPD)
+			bridge_connector->bridge_hpd = bridge;
+		if (bridge->ops & DRM_BRIDGE_OP_DETECT)
+			bridge_connector->bridge_detect = bridge;
+		if (bridge->ops & DRM_BRIDGE_OP_MODES)
+			bridge_connector->bridge_modes = bridge;
+
+		if (!drm_bridge_get_next_bridge(bridge))
+			connector_type = bridge->type;
+
+		if (bridge->ddc)
+			ddc = bridge->ddc;
+	}
+
+	if (connector_type == DRM_MODE_CONNECTOR_Unknown) {
+		kfree(bridge_connector);
+		return ERR_PTR(-EINVAL);
+	}
+
+	drm_connector_init_with_ddc(drm, connector, &drm_bridge_connector_funcs,
+				    connector_type, ddc);
+	drm_connector_helper_add(connector, &drm_bridge_connector_helper_funcs);
+
+	if (bridge_connector->bridge_hpd)
+		connector->polled = DRM_CONNECTOR_POLL_HPD;
+	else if (bridge_connector->bridge_detect)
+		connector->polled = DRM_CONNECTOR_POLL_CONNECT
+				  | DRM_CONNECTOR_POLL_DISCONNECT;
+
+	return connector;
+}
+EXPORT_SYMBOL_GPL(drm_bridge_connector_init);