[PATCH v4 04/12] drm/display: add CEC helpers code

[Dmitry Baryshkov]

Add generic CEC helpers to be used by HDMI drivers. Both notifier and
and adapter are supported for registration. Once registered, the driver
can call common set of functions to update physical address, to
invalidate it or to unregister CEC data. Unlike drm_connector_cec_funcs
(which provides interface common to all implementations, including, but
not limited to the CEC adapter, CEC notifier, CEC pin-based adapter,
etc) the struct drm_connector_hdmi_cec_adapter_ops provides callbacks
specific to the CEC adapter implementations.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
---
 drivers/gpu/drm/display/Kconfig               |   8 +-
 drivers/gpu/drm/display/Makefile              |   2 +
 drivers/gpu/drm/display/drm_hdmi_cec_helper.c | 209 ++++++++++++++++++++++++++
 include/drm/display/drm_hdmi_cec_helper.h     |  86 +++++++++++
 4 files changed, 304 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/display/Kconfig b/drivers/gpu/drm/display/Kconfig
index 3666e791d6d6eba58f095d7fb691de1fd0b95ed3..3b8fc8f99a3d89741d863749c52167beaf7be2e6 100644
--- a/drivers/gpu/drm/display/Kconfig
+++ b/drivers/gpu/drm/display/Kconfig
@@ -8,7 +8,7 @@ config DRM_DISPLAY_DP_AUX_BUS
 config DRM_DISPLAY_HELPER
 	tristate
 	depends on DRM
-	select CEC_CORE if DRM_DISPLAY_DP_AUX_CEC
+	select CEC_CORE if DRM_DISPLAY_DP_AUX_CEC || DRM_DISPLAY_HDMI_CEC_HELPER
 	help
 	  DRM helpers for display adapters.
 
@@ -82,6 +82,12 @@ config DRM_DISPLAY_HDMI_AUDIO_HELPER
 	  DRM display helpers for HDMI Audio functionality (generic HDMI Codec
 	  implementation).
 
+config DRM_DISPLAY_HDMI_CEC_HELPER
+	bool
+	select CEC_NOTIFIER
+	help
+	  DRM display helpers for HDMI CEC implementation.
+
 config DRM_DISPLAY_HDMI_HELPER
 	bool
 	help
diff --git a/drivers/gpu/drm/display/Makefile b/drivers/gpu/drm/display/Makefile
index b17879b957d5401721396e247fa346387cf6c48a..2cd078e2b81c1a9e6b336c4187b444bcb8a50e51 100644
--- a/drivers/gpu/drm/display/Makefile
+++ b/drivers/gpu/drm/display/Makefile
@@ -16,6 +16,8 @@ drm_display_helper-$(CONFIG_DRM_DISPLAY_DSC_HELPER) += \
 drm_display_helper-$(CONFIG_DRM_DISPLAY_HDCP_HELPER) += drm_hdcp_helper.o
 drm_display_helper-$(CONFIG_DRM_DISPLAY_HDMI_AUDIO_HELPER) += \
 	drm_hdmi_audio_helper.o
+drm_display_helper-$(CONFIG_DRM_DISPLAY_HDMI_CEC_HELPER) += \
+	drm_hdmi_cec_helper.o
 drm_display_helper-$(CONFIG_DRM_DISPLAY_HDMI_HELPER) += \
 	drm_hdmi_helper.o \
 	drm_scdc_helper.o
diff --git a/drivers/gpu/drm/display/drm_hdmi_cec_helper.c b/drivers/gpu/drm/display/drm_hdmi_cec_helper.c
new file mode 100644
index 0000000000000000000000000000000000000000..a6ed5f0fc3835b013a83308f5285ea0819c5702c
--- /dev/null
+++ b/drivers/gpu/drm/display/drm_hdmi_cec_helper.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright (c) 2024 Linaro Ltd
+ */
+
+#include <drm/drm_bridge.h>
+#include <drm/drm_connector.h>
+#include <drm/display/drm_hdmi_cec_helper.h>
+
+#include <linux/mutex.h>
+
+#include <media/cec.h>
+#include <media/cec-notifier.h>
+
+void drm_connector_hdmi_cec_unregister(struct drm_connector *connector)
+{
+	cec_unregister_adapter(connector->cec.adapter);
+	connector->cec.adapter = NULL;
+
+	cec_notifier_conn_unregister(connector->cec.notifier);
+	connector->cec.notifier = NULL;
+
+	connector->cec.funcs = NULL;
+}
+EXPORT_SYMBOL(drm_connector_hdmi_cec_unregister);
+
+static const struct drm_connector_cec_funcs drm_connector_hdmi_cec_funcs = {
+	.unregister = drm_connector_hdmi_cec_unregister,
+};
+
+int drm_connector_hdmi_cec_notifier_register(struct drm_connector *connector,
+					     const char *port_name,
+					     struct device *dev)
+{
+	struct cec_connector_info conn_info;
+	struct cec_notifier *notifier;
+	int ret;
+
+	mutex_lock(&connector->cec.mutex);
+
+	if (connector->cec.funcs) {
+		ret = -EBUSY;
+		goto err_unlock;
+	}
+
+	cec_fill_conn_info_from_drm(&conn_info, connector);
+
+	notifier = cec_notifier_conn_register(dev, port_name, &conn_info);
+	if (!notifier) {
+		ret = -ENOMEM;
+		goto err_unlock;
+	}
+
+	connector->cec.notifier = notifier;
+	connector->cec.funcs = &drm_connector_hdmi_cec_funcs;
+
+	mutex_unlock(&connector->cec.mutex);
+
+	return 0;
+
+err_unlock:
+	mutex_unlock(&connector->cec.mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_connector_hdmi_cec_notifier_register);
+
+#define to_hdmi_cec_adapter_ops(ops) \
+	container_of(ops, struct drm_connector_hdmi_cec_adapter_ops, base)
+
+static int drm_connector_hdmi_cec_adap_enable(struct cec_adapter *adap, bool enable)
+{
+	struct drm_connector *connector = cec_get_drvdata(adap);
+	struct drm_connector_hdmi_cec_adapter_ops *ops =
+		to_hdmi_cec_adapter_ops(connector->cec.funcs);
+
+	return ops->enable(connector, enable);
+}
+
+static int drm_connector_hdmi_cec_adap_log_addr(struct cec_adapter *adap, u8 logical_addr)
+{
+	struct drm_connector *connector = cec_get_drvdata(adap);
+	struct drm_connector_hdmi_cec_adapter_ops *ops =
+		to_hdmi_cec_adapter_ops(connector->cec.funcs);
+
+	return ops->log_addr(connector, logical_addr);
+}
+
+static int drm_connector_hdmi_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
+						u32 signal_free_time, struct cec_msg *msg)
+{
+	struct drm_connector *connector = cec_get_drvdata(adap);
+	struct drm_connector_hdmi_cec_adapter_ops *ops =
+		to_hdmi_cec_adapter_ops(connector->cec.funcs);
+
+	return ops->transmit(connector, attempts, signal_free_time, msg);
+}
+
+static const struct cec_adap_ops drm_connector_hdmi_cec_adap_ops = {
+	.adap_enable = drm_connector_hdmi_cec_adap_enable,
+	.adap_log_addr = drm_connector_hdmi_cec_adap_log_addr,
+	.adap_transmit = drm_connector_hdmi_cec_adap_transmit,
+};
+
+int drm_connector_hdmi_cec_register(struct drm_connector *connector,
+				    const struct drm_connector_hdmi_cec_adapter_ops *ops,
+				    const char *name,
+				    u8 available_las,
+				    struct device *dev)
+{
+	struct cec_connector_info conn_info;
+	struct cec_adapter *cec_adap;
+	int ret;
+
+	if (!ops->base.unregister ||
+	    !ops->init || !ops->enable || !ops->log_addr || !ops->transmit)
+		return -EINVAL;
+
+	mutex_lock(&connector->cec.mutex);
+
+	if (connector->cec.funcs) {
+		ret = -EBUSY;
+		goto err_unlock;
+	}
+
+	cec_adap = cec_allocate_adapter(&drm_connector_hdmi_cec_adap_ops, connector, name,
+					CEC_CAP_DEFAULTS | CEC_CAP_CONNECTOR_INFO,
+					available_las ? : CEC_MAX_LOG_ADDRS);
+	ret = PTR_ERR_OR_ZERO(cec_adap);
+	if (ret < 0)
+		goto err_unlock;
+
+	cec_fill_conn_info_from_drm(&conn_info, connector);
+	cec_s_conn_info(cec_adap, &conn_info);
+
+	connector->cec.adapter = cec_adap;
+	connector->cec.funcs = &ops->base;
+
+	ret = ops->init(connector);
+	if (ret < 0)
+		goto err_delete_adapter;
+
+	ret = cec_register_adapter(cec_adap, dev);
+	if (ret < 0)
+		goto err_delete_adapter;
+
+	mutex_unlock(&connector->cec.mutex);
+
+	return 0;
+
+err_delete_adapter:
+	cec_delete_adapter(cec_adap);
+
+	connector->cec.adapter = NULL;
+
+err_unlock:
+	mutex_unlock(&connector->cec.mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_connector_hdmi_cec_register);
+
+void drm_connector_hdmi_cec_received_msg(struct drm_connector *connector,
+					 struct cec_msg *msg)
+{
+	cec_received_msg(connector->cec.adapter, msg);
+}
+EXPORT_SYMBOL(drm_connector_hdmi_cec_received_msg);
+
+void drm_connector_hdmi_cec_transmit_attempt_done(struct drm_connector *connector,
+						  u8 status)
+{
+	cec_transmit_attempt_done(connector->cec.adapter, status);
+}
+EXPORT_SYMBOL(drm_connector_hdmi_cec_transmit_attempt_done);
+
+void drm_connector_hdmi_cec_transmit_done(struct drm_connector *connector,
+					  u8 status,
+					  u8 arb_lost_cnt, u8 nack_cnt,
+					  u8 low_drive_cnt, u8 error_cnt)
+{
+	cec_transmit_done(connector->cec.adapter, status,
+			  arb_lost_cnt, nack_cnt, low_drive_cnt, error_cnt);
+}
+EXPORT_SYMBOL(drm_connector_hdmi_cec_transmit_done);
+
+void drm_connector_hdmi_cec_phys_addr_invalidate(struct drm_connector *connector)
+{
+	mutex_lock(&connector->cec.mutex);
+
+	cec_phys_addr_invalidate(connector->cec.adapter);
+	cec_notifier_phys_addr_invalidate(connector->cec.notifier);
+
+	mutex_unlock(&connector->cec.mutex);
+}
+EXPORT_SYMBOL(drm_connector_hdmi_cec_phys_addr_invalidate);
+
+void drm_connector_hdmi_cec_phys_addr_set(struct drm_connector *connector)
+{
+	mutex_lock(&connector->cec.mutex);
+
+	cec_s_phys_addr(connector->cec.adapter,
+			connector->display_info.source_physical_address, false);
+	cec_notifier_set_phys_addr(connector->cec.notifier,
+				   connector->display_info.source_physical_address);
+
+	mutex_unlock(&connector->cec.mutex);
+}
+EXPORT_SYMBOL(drm_connector_hdmi_cec_phys_addr_set);
diff --git a/include/drm/display/drm_hdmi_cec_helper.h b/include/drm/display/drm_hdmi_cec_helper.h
new file mode 100644
index 0000000000000000000000000000000000000000..a9d38835c69a2939ca21a4fc921136a2a022248c
--- /dev/null
+++ b/include/drm/display/drm_hdmi_cec_helper.h
@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef DRM_DISPLAY_HDMI_CEC_HELPER
+#define DRM_DISPLAY_HDMI_CEC_HELPER
+
+#include <drm/drm_connector.h>
+
+#include <linux/types.h>
+
+struct drm_connector;
+
+struct cec_msg;
+struct device;
+
+/**
+ * struct drm_connector_hdmi_cec_adapter_ops - DRM Connector CEC Adapter callbacks
+ */
+struct drm_connector_hdmi_cec_adapter_ops {
+	/**
+	 * @base: base callbacks, providing generic DRM Connector CEC interface.
+	 */
+	struct drm_connector_cec_funcs base;
+
+	/**
+	 * @init: perform hardware-specific initialization before registering the CEC adapter
+	 */
+	int (*init)(struct drm_connector *connector);
+
+	/**
+	 * @uninit: perform hardware-specific teardown for the CEC adapter
+	 */
+	void (*uninit)(struct drm_connector *connector);
+
+	/**
+	 * @enable: enable or disable CEC adapter
+	 */
+	int (*enable)(struct drm_connector *connector, bool enable);
+
+	/**
+	 * @log_addr: set adapter's logical address, can be called multiple
+	 * times if adapter supports several LAs
+	 */
+	int (*log_addr)(struct drm_connector *connector, u8 logical_addr);
+
+	/**
+	 * @transmit: start transmission of the specified CEC message
+	 */
+	int (*transmit)(struct drm_connector *connector, u8 attempts,
+			u32 signal_free_time, struct cec_msg *msg);
+};
+
+int drm_connector_hdmi_cec_register(struct drm_connector *connector,
+				    const struct drm_connector_hdmi_cec_adapter_ops *ops,
+				    const char *name,
+				    u8 available_las,
+				    struct device *dev);
+
+int drm_connector_hdmi_cec_notifier_register(struct drm_connector *connector,
+					     const char *port_name,
+					     struct device *dev);
+
+void drm_connector_hdmi_cec_unregister(struct drm_connector *connector);
+
+void drm_connector_hdmi_cec_received_msg(struct drm_connector *connector,
+					 struct cec_msg *msg);
+
+void drm_connector_hdmi_cec_transmit_done(struct drm_connector *connector,
+					  u8 status,
+					  u8 arb_lost_cnt, u8 nack_cnt,
+					  u8 low_drive_cnt, u8 error_cnt);
+
+void drm_connector_hdmi_cec_transmit_attempt_done(struct drm_connector *connector,
+						  u8 status);
+/*
+ * These functions are used by the state helper, so we end up linking to the
+ * same module. Define stubs to simplify the code.
+ */
+#ifdef CONFIG_DRM_DISPLAY_HDMI_CEC_HELPER
+void drm_connector_hdmi_cec_phys_addr_invalidate(struct drm_connector *connector);
+void drm_connector_hdmi_cec_phys_addr_set(struct drm_connector *connector);
+#else
+static inline void drm_connector_hdmi_cec_phys_addr_invalidate(struct drm_connector *connector) {}
+static inline void drm_connector_hdmi_cec_phys_addr_set(struct drm_connector *connector) {}
+#endif
+
+#endif

-- 
2.39.5