[PATCH v7 2/9] drm/bridge: Implement generic USB Type-C DP HPD bridge

[Chaoyi Chen <kernel@airkyi.com>]

From: Chaoyi Chen <chaoyi.chen@rock-chips.com>

Several USB-C controller drivers have already implemented the DP HPD
bridge function provided by aux-hpd-bridge.c, but there are still
some USB-C controller driver that have not yet implemented it.

This patch implements a generic DP HPD bridge based on aux-hpd-bridge.c,
so that other USB-C controller drivers don't need to implement it again.

Signed-off-by: Chaoyi Chen <chaoyi.chen@rock-chips.com>
---
 drivers/gpu/drm/bridge/Kconfig                | 11 ++++
 drivers/gpu/drm/bridge/Makefile               |  1 +
 .../gpu/drm/bridge/aux-hpd-typec-dp-bridge.c  | 51 +++++++++++++++++++
 3 files changed, 63 insertions(+)
 create mode 100644 drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index b9e0ca85226a..9f31540d3ad8 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -33,6 +33,17 @@ config DRM_AUX_HPD_BRIDGE
 menu "Display Interface Bridges"
 	depends on DRM && DRM_BRIDGE
 
+config DRM_AUX_TYPEC_DP_HPD_BRIDGE
+	tristate "TypeC DP HPD bridge"
+	depends on DRM_BRIDGE && OF && TYPEC
+	select DRM_AUX_HPD_BRIDGE
+	help
+	  Simple USB Type-C DP bridge that terminates the bridge chain and
+	  provides HPD support.
+
+	  If the USB-C controller driver has not implemented this and you need
+	  the DP HPD support, say "Y" or "m" here.
+
 config DRM_CHIPONE_ICN6211
 	tristate "Chipone ICN6211 MIPI-DSI/RGB Converter bridge"
 	depends on OF
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index 245e8a27e3fc..e91736829167 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_DRM_AUX_BRIDGE) += aux-bridge.o
 obj-$(CONFIG_DRM_AUX_HPD_BRIDGE) += aux-hpd-bridge.o
+obj-$(CONFIG_DRM_AUX_TYPEC_DP_HPD_BRIDGE) += aux-hpd-typec-dp-bridge.o
 obj-$(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
diff --git a/drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c b/drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c
new file mode 100644
index 000000000000..2235b7438fe9
--- /dev/null
+++ b/drivers/gpu/drm/bridge/aux-hpd-typec-dp-bridge.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include <linux/of.h>
+#include <linux/usb/typec_altmode.h>
+#include <linux/usb/typec_dp.h>
+#include <linux/usb/typec_notify.h>
+
+#include <drm/bridge/aux-bridge.h>
+
+static int drm_typec_bus_event(struct notifier_block *nb,
+			       unsigned long action, void *data)
+{
+	struct typec_altmode *alt = (struct typec_altmode *)data;
+
+	if (action != TYPEC_ALTMODE_REGISTERED)
+		goto done;
+
+	if (alt->svid != USB_TYPEC_DP_SID)
+		goto done;
+
+	/*
+	 * alt->dev.parent->parent : USB-C controller device
+	 * alt->dev.parent         : USB-C connector device
+	 */
+	drm_dp_hpd_bridge_register(alt->dev.parent->parent,
+				   to_of_node(alt->dev.parent->fwnode));
+
+done:
+	return NOTIFY_OK;
+}
+
+static struct notifier_block drm_typec_event_nb = {
+	.notifier_call = drm_typec_bus_event,
+};
+
+static void drm_aux_hpd_typec_dp_bridge_module_exit(void)
+{
+	typec_unregister_notify(&drm_typec_event_nb);
+}
+
+static int __init drm_aux_hpd_typec_dp_bridge_module_init(void)
+{
+	typec_register_notify(&drm_typec_event_nb);
+
+	return 0;
+}
+
+module_init(drm_aux_hpd_typec_dp_bridge_module_init);
+module_exit(drm_aux_hpd_typec_dp_bridge_module_exit);
+
+MODULE_DESCRIPTION("DRM TYPEC DP HPD BRIDGE");
+MODULE_LICENSE("GPL");
-- 
2.49.0