[PATCH 1/4] usb: typec: Add port registration notifier

Prashant Malani
2021-11-24T23:11:51Z

Introduce a blocking notifier to be called when a new Type C port gets
registered with the connector class framework.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
---
NOTE: typec_port_registration_register_notify() is a bit long,
so please let me know if you have any shorter suggestions for naming
this function.

drivers/usb/typec/class.c | 30 ++++++++++++++++++++++++++++++
include/linux/usb/typec.h | 13 +++++++++++++
2 files changed, 43 insertions(+)

diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
index aeef453aa658..14b82109b0f5 100644
--- a/drivers/usb/typec/class.c
+++ b/drivers/usb/typec/class.c
@@ -16,6 +16,8 @@
#include "bus.h"
#include "class.h"

+static BLOCKING_NOTIFIER_HEAD(typec_port_registration_notifier);
+
static DEFINE_IDA(typec_index_ida);

struct class typec_class = {
@@ -1979,6 +1981,32 @@ void typec_port_register_altmodes(struct typec_port *port,
}
EXPORT_SYMBOL_GPL(typec_port_register_altmodes);

+/**
+ * typec_port_registration_register_notify - Register a notifier for Type C port registration.
+ * @nb: notifier block to signal
+ *
+ * This function allows callers to get a notification when a Type C port is registered with
+ * the connector class.
+ */
+int typec_port_registration_register_notify(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_register(&typec_port_registration_notifier, nb);
+}
+EXPORT_SYMBOL_GPL(typec_port_registration_register_notify);
+
+/**
+ * typec_port_registration_unregister_notify - Unregister a notifier for Type C port registration.
+ * @nb: notifier block to unregister
+ *
+ * This function allows callers to unregister notifiers which were previously registered using
+ * typec_port_registration_register_notify().
+ */
+int typec_port_registration_unregister_notify(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_unregister(&typec_port_registration_notifier, nb);
+}
+EXPORT_SYMBOL_GPL(typec_port_registration_unregister_notify);
+
/**
* typec_register_port - Register a USB Type-C Port
* @parent: Parent device
@@ -2086,6 +2114,8 @@ struct typec_port *typec_register_port(struct device *parent,
if (ret)
dev_warn(&port->dev, "failed to create symlinks (%d)\n", ret);

+ blocking_notifier_call_chain(&typec_port_registration_notifier, 0, port);
+
return port;
}
EXPORT_SYMBOL_GPL(typec_register_port);
diff --git a/include/linux/usb/typec.h b/include/linux/usb/typec.h
index e2e44bb1dad8..398317835f24 100644
--- a/include/linux/usb/typec.h
+++ b/include/linux/usb/typec.h
@@ -3,6 +3,7 @@
#ifndef __LINUX_USB_TYPEC_H
#define __LINUX_USB_TYPEC_H

+#include <linux/notifier.h>
#include <linux/types.h>

/* USB Type-C Specification releases */
@@ -308,6 +309,8 @@ int typec_get_negotiated_svdm_version(struct typec_port *port);
#if IS_REACHABLE(CONFIG_TYPEC)
int typec_link_port(struct device *port);
void typec_unlink_port(struct device *port);
+int typec_port_registration_register_notify(struct notifier_block *nb);
+int typec_port_registration_unregister_notify(struct notifier_block *nb);
#else
static inline int typec_link_port(struct device *port)
{
@@ -315,6 +318,16 @@ static inline int typec_link_port(struct device *port)
}

static inline void typec_unlink_port(struct device *port) { }
+
+int typec_port_registration_register_notify(struct notifier_block *nb)
+{
+ return 0;
+}
+
+int typec_port_registration_unregister_notify(struct notifier_block *nb)
+{
+ return 0;
+}
#endif

#endif /* __LINUX_USB_TYPEC_H */
--
2.34.0.rc2.393.gf8c9666880-goog