usb: typec: API for controlling USB Type-C Multiplexers

USB Type-C connectors consist of various muxes and switches
that route the pins on the connector to the right locations.
The USB Type-C drivers need to be able to control the muxes,
as they are the ones that know things like the cable plug
orientation, and the current mode that was negotiated with
the partner.

This introduces a small API for registering and controlling
cable plug orientation switches, and separate small API for
registering and controlling pin multiplexer/demultiplexer
switches that are needed with Accessory/Alternate Modes.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 262 insertions, 0 deletions

diff --git a/drivers/usb/typec/Makefile b/drivers/usb/typec/Makefile
index bb3138a6eaac..56b2e9516ec1 100644
--- a/drivers/usb/typec/Makefile
+++ b/drivers/usb/typec/Makefile
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_TYPEC)		+= typec.o
+typec-y				:= class.o mux.o
 obj-$(CONFIG_TYPEC_TCPM)	+= tcpm.o
 obj-y				+= fusb302/
 obj-$(CONFIG_TYPEC_WCOVE)	+= typec_wcove.o
diff --git a/drivers/usb/typec/typec.c b/drivers/usb/typec/class.c
index dc28ad868d93..2620a694704f 100644
--- a/drivers/usb/typec/typec.c
+++ b/drivers/usb/typec/class.c
@@ -11,6 +11,7 @@
 #include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/usb/typec.h>
+#include <linux/usb/typec_mux.h>
 
 struct typec_mode {
 	int				index;
@@ -70,6 +71,10 @@ struct typec_port {
 	enum typec_port_type		port_type;
 	struct mutex			port_type_lock;
 
+	enum typec_orientation		orientation;
+	struct typec_switch		*sw;
+	struct typec_mux		*mux;
+
 	const struct typec_capability	*cap;
 };
 
@@ -92,6 +97,7 @@ static const struct device_type typec_port_dev_type;
 static DEFINE_IDA(typec_index_ida);
 static struct class *typec_class;
 
+/* ------------------------------------------------------------------------- */
 /* Common attributes */
 
 static const char * const typec_accessory_modes[] = {
@@ -1137,6 +1143,8 @@ static void typec_release(struct device *dev)
 	struct typec_port *port = to_typec_port(dev);
 
 	ida_simple_remove(&typec_index_ida, port->id);
+	typec_switch_put(port->sw);
+	typec_mux_put(port->mux);
 	kfree(port);
 }
 
@@ -1246,6 +1254,47 @@ void typec_set_pwr_opmode(struct typec_port *port,
 }
 EXPORT_SYMBOL_GPL(typec_set_pwr_opmode);
 
+/* ------------------------------------------ */
+/* API for Multiplexer/DeMultiplexer Switches */
+
+/**
+ * typec_set_orientation - Set USB Type-C cable plug orientation
+ * @port: USB Type-C Port
+ * @orientation: USB Type-C cable plug orientation
+ *
+ * Set cable plug orientation for @port.
+ */
+int typec_set_orientation(struct typec_port *port,
+			  enum typec_orientation orientation)
+{
+	int ret;
+
+	if (port->sw) {
+		ret = port->sw->set(port->sw, orientation);
+		if (ret)
+			return ret;
+	}
+
+	port->orientation = orientation;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(typec_set_orientation);
+
+/**
+ * typec_set_mode - Set mode of operation for USB Type-C connector
+ * @port: USB Type-C port for the connector
+ * @mode: Operation mode for the connector
+ *
+ * Set mode @mode for @port. This function will configure the muxes needed to
+ * enter @mode.
+ */
+int typec_set_mode(struct typec_port *port, int mode)
+{
+	return port->mux ? port->mux->set(port->mux, mode) : 0;
+}
+EXPORT_SYMBOL_GPL(typec_set_mode);
+
 /* --------------------------------------- */
 
 /**
@@ -1293,6 +1342,18 @@ struct typec_port *typec_register_port(struct device *parent,
 		return ERR_PTR(id);
 	}
 
+	port->sw = typec_switch_get(cap->fwnode ? &port->dev : parent);
+	if (IS_ERR(port->sw)) {
+		ret = PTR_ERR(port->sw);
+		goto err_switch;
+	}
+
+	port->mux = typec_mux_get(cap->fwnode ? &port->dev : parent);
+	if (IS_ERR(port->mux)) {
+		ret = PTR_ERR(port->mux);
+		goto err_mux;
+	}
+
 	if (cap->type == TYPEC_PORT_DFP)
 		role = TYPEC_SOURCE;
 	else if (cap->type == TYPEC_PORT_UFP)
@@ -1330,6 +1391,15 @@ struct typec_port *typec_register_port(struct device *parent,
 	}
 
 	return port;
+
+err_mux:
+	typec_switch_put(port->sw);
+
+err_switch:
+	ida_simple_remove(&typec_index_ida, port->id);
+	kfree(port);
+
+	return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_GPL(typec_register_port);
 
diff --git a/drivers/usb/typec/mux.c b/drivers/usb/typec/mux.c
new file mode 100644
index 000000000000..f89093bd7185
--- /dev/null
+++ b/drivers/usb/typec/mux.c
@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: GPL-2.0
+/**
+ * USB Type-C Multiplexer/DeMultiplexer Switch support
+ *
+ * Copyright (C) 2018 Intel Corporation
+ * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
+ *         Hans de Goede <hdegoede@redhat.com>
+ */
+
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/usb/typec_mux.h>
+
+static DEFINE_MUTEX(switch_lock);
+static DEFINE_MUTEX(mux_lock);
+static LIST_HEAD(switch_list);
+static LIST_HEAD(mux_list);
+
+static void *typec_switch_match(struct device_connection *con, int ep,
+				void *data)
+{
+	struct typec_switch *sw;
+
+	list_for_each_entry(sw, &switch_list, entry)
+		if (!strcmp(con->endpoint[ep], dev_name(sw->dev)))
+			return sw;
+
+	/*
+	 * We only get called if a connection was found, tell the caller to
+	 * wait for the switch to show up.
+	 */
+	return ERR_PTR(-EPROBE_DEFER);
+}
+
+/**
+ * typec_switch_get - Find USB Type-C orientation switch
+ * @dev: The caller device
+ *
+ * Finds a switch linked with @dev. Returns a reference to the switch on
+ * success, NULL if no matching connection was found, or
+ * ERR_PTR(-EPROBE_DEFER) when a connection was found but the switch
+ * has not been enumerated yet.
+ */
+struct typec_switch *typec_switch_get(struct device *dev)
+{
+	struct typec_switch *sw;
+
+	mutex_lock(&switch_lock);
+	sw = device_connection_find_match(dev, "typec-switch", NULL,
+					  typec_switch_match);
+	if (!IS_ERR_OR_NULL(sw))
+		get_device(sw->dev);
+	mutex_unlock(&switch_lock);
+
+	return sw;
+}
+EXPORT_SYMBOL_GPL(typec_switch_get);
+
+/**
+ * typec_put_switch - Release USB Type-C orientation switch
+ * @sw: USB Type-C orientation switch
+ *
+ * Decrement reference count for @sw.
+ */
+void typec_switch_put(struct typec_switch *sw)
+{
+	if (!IS_ERR_OR_NULL(sw))
+		put_device(sw->dev);
+}
+EXPORT_SYMBOL_GPL(typec_switch_put);
+
+/**
+ * typec_switch_register - Register USB Type-C orientation switch
+ * @sw: USB Type-C orientation switch
+ *
+ * This function registers a switch that can be used for routing the correct
+ * data pairs depending on the cable plug orientation from the USB Type-C
+ * connector to the USB controllers. USB Type-C plugs can be inserted
+ * right-side-up or upside-down.
+ */
+int typec_switch_register(struct typec_switch *sw)
+{
+	mutex_lock(&switch_lock);
+	list_add_tail(&sw->entry, &switch_list);
+	mutex_unlock(&switch_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(typec_switch_register);
+
+/**
+ * typec_switch_unregister - Unregister USB Type-C orientation switch
+ * @sw: USB Type-C orientation switch
+ *
+ * Unregister switch that was registered with typec_switch_register().
+ */
+void typec_switch_unregister(struct typec_switch *sw)
+{
+	mutex_lock(&switch_lock);
+	list_del(&sw->entry);
+	mutex_unlock(&switch_lock);
+}
+EXPORT_SYMBOL_GPL(typec_switch_unregister);
+
+/* ------------------------------------------------------------------------- */
+
+static void *typec_mux_match(struct device_connection *con, int ep, void *data)
+{
+	struct typec_mux *mux;
+
+	list_for_each_entry(mux, &mux_list, entry)
+		if (!strcmp(con->endpoint[ep], dev_name(mux->dev)))
+			return mux;
+
+	/*
+	 * We only get called if a connection was found, tell the caller to
+	 * wait for the switch to show up.
+	 */
+	return ERR_PTR(-EPROBE_DEFER);
+}
+
+/**
+ * typec_mux_get - Find USB Type-C Multiplexer
+ * @dev: The caller device
+ *
+ * Finds a mux linked to the caller. This function is primarily meant for the
+ * Type-C drivers. Returns a reference to the mux on success, NULL if no
+ * matching connection was found, or ERR_PTR(-EPROBE_DEFER) when a connection
+ * was found but the mux has not been enumerated yet.
+ */
+struct typec_mux *typec_mux_get(struct device *dev)
+{
+	struct typec_mux *mux;
+
+	mutex_lock(&mux_lock);
+	mux = device_connection_find_match(dev, "typec-mux", NULL,
+					   typec_mux_match);
+	if (!IS_ERR_OR_NULL(mux))
+		get_device(mux->dev);
+	mutex_unlock(&mux_lock);
+
+	return mux;
+}
+EXPORT_SYMBOL_GPL(typec_mux_get);
+
+/**
+ * typec_mux_put - Release handle to a Multiplexer
+ * @mux: USB Type-C Connector Multiplexer/DeMultiplexer
+ *
+ * Decrements reference count for @mux.
+ */
+void typec_mux_put(struct typec_mux *mux)
+{
+	if (!IS_ERR_OR_NULL(mux))
+		put_device(mux->dev);
+}
+EXPORT_SYMBOL_GPL(typec_mux_put);
+
+/**
+ * typec_mux_register - Register Multiplexer routing USB Type-C pins
+ * @mux: USB Type-C Connector Multiplexer/DeMultiplexer
+ *
+ * USB Type-C connectors can be used for alternate modes of operation besides
+ * USB when Accessory/Alternate Modes are supported. With some of those modes,
+ * the pins on the connector need to be reconfigured. This function registers
+ * multiplexer switches routing the pins on the connector.
+ */
+int typec_mux_register(struct typec_mux *mux)
+{
+	mutex_lock(&mux_lock);
+	list_add_tail(&mux->entry, &mux_list);
+	mutex_unlock(&mux_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(typec_mux_register);
+
+/**
+ * typec_mux_unregister - Unregister Multiplexer Switch
+ * @sw: USB Type-C Connector Multiplexer/DeMultiplexer
+ *
+ * Unregister mux that was registered with typec_mux_register().
+ */
+void typec_mux_unregister(struct typec_mux *mux)
+{
+	mutex_lock(&mux_lock);
+	list_del(&mux->entry);
+	mutex_unlock(&mux_lock);
+}
+EXPORT_SYMBOL_GPL(typec_mux_unregister);