[PATCH v4 09/18] drm/bridge: dp_typec: Allow users to hook hpd notify path

[Stephen Boyd]

The previous patch added support for no-hpd to drm_dp_typec_bridge code.
Allow users of this bridge to hook the HPD notification path of the
bridge chain so that they can be made aware of the connector status
changing. This helps HPD-less users of the bridge inject the HPD state
into their code by using the connector status as a proxy for HPD being
asserted or deasserted.

In particular, this will help Trogdor/Strongbad boards that need to read
the EC's analog mux which steers the DP signal to one or the other USB
type-c ports to figure out which type-c port has HPD asserted.

Cc: Prashant Malani <pmalani at chromium.org>
Cc: Benson Leung <bleung at chromium.org>
Cc: Tzung-Bi Shih <tzungbi at kernel.org>
Cc: <chrome-platform at lists.linux.dev>
Cc: Pin-yen Lin <treapking at chromium.org>
Cc: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
Signed-off-by: Stephen Boyd <swboyd at chromium.org>
---
 drivers/gpu/drm/bridge/aux-hpd-bridge.c | 31 +++++++++++++++++++++++++
 include/drm/bridge/aux-bridge.h         |  9 +++++++
 2 files changed, 40 insertions(+)

diff --git a/drivers/gpu/drm/bridge/aux-hpd-bridge.c b/drivers/gpu/drm/bridge/aux-hpd-bridge.c
index 52db36aa190b..8ff8716b2630 100644
--- a/drivers/gpu/drm/bridge/aux-hpd-bridge.c
+++ b/drivers/gpu/drm/bridge/aux-hpd-bridge.c
@@ -93,6 +93,8 @@ struct drm_dp_typec_bridge_dev {
 	struct auxiliary_device adev;
 	size_t max_lanes;
 	size_t num_typec_ports;
+	void (*hpd_notify)(void *data, enum drm_connector_status status);
+	void *hpd_data;
 };
 
 static inline struct drm_dp_typec_bridge_dev *
@@ -324,6 +326,21 @@ devm_drm_dp_typec_bridge_alloc(struct device *parent, struct device_node *np)
 }
 EXPORT_SYMBOL_GPL(devm_drm_dp_typec_bridge_alloc);
 
+/**
+ * drm_dp_typec_bridge_add_hpd_notify: Register a callback called when the
+ * bridge chain hpd state changes
+ * @typec_bridge_dev: USB type-c DisplayPort bridge
+ * @hpd_notify: callback for bridge hot plug detect events
+ * @hpd_data: data passed to @hpd_notify callback
+ */
+void drm_dp_typec_bridge_add_hpd_notify(struct drm_dp_typec_bridge_dev *typec_bridge_dev,
+					hpd_notify_fn_t hpd_notify, void *hpd_data)
+{
+	typec_bridge_dev->hpd_notify = hpd_notify;
+	typec_bridge_dev->hpd_data = hpd_data;
+}
+EXPORT_SYMBOL_GPL(drm_dp_typec_bridge_add_hpd_notify);
+
 /**
  * devm_drm_dp_typec_bridge_add - register a USB type-c DisplayPort bridge
  * @dev: struct device to tie registration lifetime to
@@ -363,6 +380,19 @@ void drm_aux_hpd_bridge_notify(struct device *dev, enum drm_connector_status sta
 }
 EXPORT_SYMBOL_GPL(drm_aux_hpd_bridge_notify);
 
+static void drm_dp_typec_bridge_hpd_notify(struct drm_bridge *bridge,
+					    enum drm_connector_status status)
+{
+	struct drm_dp_typec_bridge_data *data;
+	struct drm_dp_typec_bridge_dev *typec_bridge_dev;
+
+	data = to_drm_dp_typec_bridge_data(bridge);
+	typec_bridge_dev = to_drm_dp_typec_bridge_dev(data->hpd_bridge.dev);
+
+	if (typec_bridge_dev->hpd_notify)
+		typec_bridge_dev->hpd_notify(typec_bridge_dev->hpd_data, status);
+}
+
 static int drm_aux_hpd_bridge_attach(struct drm_bridge *bridge,
 				     enum drm_bridge_attach_flags flags)
 {
@@ -520,6 +550,7 @@ static const struct drm_bridge_funcs drm_dp_typec_bridge_funcs = {
 	.atomic_reset = drm_atomic_helper_bridge_reset,
 	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
+	.hpd_notify = drm_dp_typec_bridge_hpd_notify,
 };
 
 static int drm_dp_typec_bridge_orientation_set(struct typec_switch_dev *sw,
diff --git a/include/drm/bridge/aux-bridge.h b/include/drm/bridge/aux-bridge.h
index 73fc8582ec07..300f4a203a9b 100644
--- a/include/drm/bridge/aux-bridge.h
+++ b/include/drm/bridge/aux-bridge.h
@@ -22,6 +22,8 @@ static inline int drm_aux_bridge_register(struct device *parent)
 
 struct drm_dp_typec_bridge_dev;
 
+typedef void (*hpd_notify_fn_t)(void *data, enum drm_connector_status status);
+
 #if IS_ENABLED(CONFIG_DRM_AUX_HPD_BRIDGE)
 struct auxiliary_device *devm_drm_dp_hpd_bridge_alloc(struct device *parent, struct device_node *np);
 int devm_drm_dp_hpd_bridge_add(struct device *dev, struct auxiliary_device *adev);
@@ -30,6 +32,8 @@ struct device *drm_dp_hpd_bridge_register(struct device *parent,
 void drm_aux_hpd_bridge_notify(struct device *dev, enum drm_connector_status status);
 struct drm_dp_typec_bridge_dev *devm_drm_dp_typec_bridge_alloc(struct device *parent,
 							       struct device_node *np);
+void drm_dp_typec_bridge_add_hpd_notify(struct drm_dp_typec_bridge_dev *typec_bridge_dev,
+					hpd_notify_fn_t hpd_notify, void *hpd_data);
 int devm_drm_dp_typec_bridge_add(struct device *dev, struct drm_dp_typec_bridge_dev *typec_bridge_dev);
 #else
 static inline struct auxiliary_device *devm_drm_dp_hpd_bridge_alloc(struct device *parent,
@@ -55,6 +59,11 @@ devm_drm_dp_typec_bridge_alloc(struct device *parent, struct device_node *np)
 	return NULL;
 }
 
+static inline void drm_dp_typec_bridge_add_hpd_notify(struct drm_dp_typec_bridge_dev *typec_bridge_dev,
+						      hpd_notify_fn_t hpd_notify, void *hpd_data)
+{
+}
+
 static inline int devm_drm_dp_typec_bridge_add(struct device *dev,
 					       struct drm_dp_typec_bridge_dev *typec_bridge_dev)
 {
-- 
https://chromeos.dev