[PATCH v2 3/6] usb: typec: Port mapping utility

Heikki Krogerus
2021-03-29T09:05:21Z

Adding functions that can be used to link/unlink ports -
USB ports, TBT3/USB4 ports, DisplayPorts and so on - to
the USB Type-C connectors they are attached to inside a
system. The symlink that is created for the port device is
named "connector".

Initially only ACPI is supported. ACPI port object shares
the _PLD (Physical Location of Device) with the USB Type-C
connector that it's attached to.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
---
drivers/usb/typec/Makefile | 2 +-
drivers/usb/typec/class.c | 7 +-
drivers/usb/typec/class.h | 9 ++
drivers/usb/typec/port-mapper.c | 219 ++++++++++++++++++++++++++++++++
include/linux/usb/typec.h | 13 ++
5 files changed, 248 insertions(+), 2 deletions(-)
create mode 100644 drivers/usb/typec/port-mapper.c

diff --git a/drivers/usb/typec/Makefile b/drivers/usb/typec/Makefile
index a820e6e8c1ffc..1e1868832b8d8 100644
--- a/drivers/usb/typec/Makefile
+++ b/drivers/usb/typec/Makefile
@@ -3,7 +3,7 @@
CFLAGS_tps6598x.o := -I$(src)

obj-$(CONFIG_TYPEC) += typec.o
-typec-y := class.o mux.o bus.o
+typec-y := class.o mux.o bus.o port-mapper.o
obj-$(CONFIG_TYPEC) += altmodes/
obj-$(CONFIG_TYPEC_TCPM) += tcpm/
obj-$(CONFIG_TYPEC_UCSI) += ucsi/
diff --git a/drivers/usb/typec/class.c b/drivers/usb/typec/class.c
index d3e1002386357..ff199e2d26c7b 100644
--- a/drivers/usb/typec/class.c
+++ b/drivers/usb/typec/class.c
@@ -18,7 +18,7 @@

static DEFINE_IDA(typec_index_ida);

-static struct class typec_class = {
+struct class typec_class = {
.name = "typec",
.owner = THIS_MODULE,
};
@@ -1601,6 +1601,7 @@ static void typec_release(struct device *dev)
ida_destroy(&port->mode_ids);
typec_switch_put(port->sw);
typec_mux_put(port->mux);
+ free_pld(port->pld);
kfree(port->cap);
kfree(port);
}
@@ -1983,6 +1984,8 @@ struct typec_port *typec_register_port(struct device *parent,

ida_init(&port->mode_ids);
mutex_init(&port->port_type_lock);
+ mutex_init(&port->port_list_lock);
+ INIT_LIST_HEAD(&port->port_list);

port->id = id;
port->ops = cap->ops;
@@ -2024,6 +2027,8 @@ struct typec_port *typec_register_port(struct device *parent,
return ERR_PTR(ret);
}

+ port->pld = get_pld(&port->dev);
+
return port;
}
EXPORT_SYMBOL_GPL(typec_register_port);
diff --git a/drivers/usb/typec/class.h b/drivers/usb/typec/class.h
index d414be58d122e..52294f7020a8b 100644
--- a/drivers/usb/typec/class.h
+++ b/drivers/usb/typec/class.h
@@ -54,6 +54,11 @@ struct typec_port {

const struct typec_capability *cap;
const struct typec_operations *ops;
+
+ struct list_head port_list;
+ struct mutex port_list_lock; /* Port list lock */
+
+ void *pld;
};

#define to_typec_port(_dev_) container_of(_dev_, struct typec_port, dev)
@@ -72,5 +77,9 @@ extern const struct device_type typec_port_dev_type;
#define is_typec_port(dev) ((dev)->type == &typec_port_dev_type)

extern struct class typec_mux_class;
+extern struct class typec_class;
+
+void *get_pld(struct device *dev);
+void free_pld(void *pld);

#endif /* __USB_TYPEC_CLASS__ */
diff --git a/drivers/usb/typec/port-mapper.c b/drivers/usb/typec/port-mapper.c
new file mode 100644
index 0000000000000..5bee7a97242fe
--- /dev/null
+++ b/drivers/usb/typec/port-mapper.c
@@ -0,0 +1,219 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * USB Type-C Connector Class Port Mapping Utility
+ *
+ * Copyright (C) 2021, Intel Corporation
+ * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/usb.h>
+#include <linux/usb/typec.h>
+
+#include "class.h"
+
+struct port_node {
+ struct list_head list;
+ struct device *dev;
+ void *pld;
+};
+
+static int acpi_pld_match(const struct acpi_pld_info *pld1,
+ const struct acpi_pld_info *pld2)
+{
+ if (!pld1 || !pld2)
+ return 0;
+
+ /*
+ * To speed things up, first checking only the group_position. It seems
+ * to often have the first unique value in the _PLD.
+ */
+ if (pld1->group_position == pld2->group_position)
+ return !memcmp(pld1, pld2, sizeof(struct acpi_pld_info));
+
+ return 0;
+}
+
+void *get_pld(struct device *dev)
+{
+#ifdef CONFIG_ACPI
+ struct acpi_pld_info *pld;
+ acpi_status status;
+
+ if (!has_acpi_companion(dev))
+ return NULL;
+
+ status = acpi_get_physical_device_location(ACPI_HANDLE(dev), &pld);
+ if (ACPI_FAILURE(status))
+ return NULL;
+
+ return pld;
+#else
+ return NULL;
+#endif
+}
+
+void free_pld(void *pld)
+{
+#ifdef CONFIG_ACPI
+ ACPI_FREE(pld);
+#endif
+}
+
+static int __link_port(struct typec_port *con, struct port_node *node)
+{
+ int ret;
+
+ ret = sysfs_create_link(&node->dev->kobj, &con->dev.kobj, "connector");
+ if (ret)
+ return ret;
+
+ ret = sysfs_create_link(&con->dev.kobj, &node->dev->kobj,
+ dev_name(node->dev));
+ if (ret) {
+ sysfs_remove_link(&node->dev->kobj, "connector");
+ return ret;
+ }
+
+ list_add_tail(&node->list, &con->port_list);
+
+ return 0;
+}
+
+static int link_port(struct typec_port *con, struct port_node *node)
+{
+ int ret;
+
+ mutex_lock(&con->port_list_lock);
+ ret = __link_port(con, node);
+ mutex_unlock(&con->port_list_lock);
+
+ return ret;
+}
+
+static void __unlink_port(struct typec_port *con, struct port_node *node)
+{
+ sysfs_remove_link(&con->dev.kobj, dev_name(node->dev));
+ sysfs_remove_link(&node->dev->kobj, "connector");
+ list_del(&node->list);
+}
+
+static void unlink_port(struct typec_port *con, struct port_node *node)
+{
+ mutex_lock(&con->port_list_lock);
+ __unlink_port(con, node);
+ mutex_unlock(&con->port_list_lock);
+}
+
+static struct port_node *create_port_node(struct device *port)
+{
+ struct port_node *node;
+
+ node = kzalloc(sizeof(*node), GFP_KERNEL);
+ if (!node)
+ return ERR_PTR(-ENOMEM);
+
+ node->dev = get_device(port);
+ node->pld = get_pld(port);
+
+ return node;
+}
+
+static void remove_port_node(struct port_node *node)
+{
+ put_device(node->dev);
+ free_pld(node->pld);
+ kfree(node);
+}
+
+static int connector_match(struct device *dev, const void *data)
+{
+ const struct port_node *node = data;
+
+ if (!is_typec_port(dev))
+ return 0;
+
+ return acpi_pld_match(to_typec_port(dev)->pld, node->pld);
+}
+
+static struct device *find_connector(struct port_node *node)
+{
+ if (!node->pld)
+ return NULL;
+
+ return class_find_device(&typec_class, NULL, node, connector_match);
+}
+
+/**
+ * typec_link_port - Link a port to its connector
+ * @port: The port device
+ *
+ * Find the connector of @port and create symlink named "connector" for it.
+ * Returns 0 on success, or errno in case of a failure.
+ *
+ * NOTE. The function increments the reference count of @port on success.
+ */
+int typec_link_port(struct device *port)
+{
+ struct device *connector;
+ struct port_node *node;
+ int ret = 0;
+
+ node = create_port_node(port);
+ if (IS_ERR(node))
+ return PTR_ERR(node);
+
+ connector = find_connector(node);
+ if (!connector)
+ goto remove_node;
+
+ ret = link_port(to_typec_port(connector), node);
+ if (ret)
+ goto put_connector;
+
+ return 0;
+
+put_connector:
+ put_device(connector);
+remove_node:
+ remove_port_node(node);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(typec_link_port);
+
+static int port_match_and_unlink(struct device *connector, void *port)
+{
+ struct port_node *node;
+ struct port_node *tmp;
+ int ret = 0;
+
+ if (!is_typec_port(connector))
+ return 0;
+
+ mutex_lock(&to_typec_port(connector)->port_list_lock);
+ list_for_each_entry_safe(node, tmp, &to_typec_port(connector)->port_list, list) {
+ ret = node->dev == port;
+ if (ret) {
+ unlink_port(to_typec_port(connector), node);
+ remove_port_node(node);
+ put_device(connector);
+ break;
+ }
+ }
+ mutex_unlock(&to_typec_port(connector)->port_list_lock);
+
+ return ret;
+}
+
+/**
+ * typec_unlink_port - Unlink port from its connector
+ * @port: The port device
+ *
+ * Removes the symlink "connector" and decrements the reference count of @port.
+ */
+void typec_unlink_port(struct device *port)
+{
+ class_for_each_device(&typec_class, NULL, port, port_match_and_unlink);
+}
+EXPORT_SYMBOL_GPL(typec_unlink_port);
diff --git a/include/linux/usb/typec.h b/include/linux/usb/typec.h
index 91b4303ca305c..604cd2da15e83 100644
--- a/include/linux/usb/typec.h
+++ b/include/linux/usb/typec.h
@@ -298,4 +298,17 @@ int typec_find_port_data_role(const char *name);
void typec_partner_set_svdm_version(struct typec_partner *partner,
enum usb_pd_svdm_ver svdm_version);
int typec_get_negotiated_svdm_version(struct typec_port *port);
+
+#if IS_ENABLED(CONFIG_ACPI) && IS_REACHABLE(CONFIG_TYPEC)
+int typec_link_port(struct device *port);
+void typec_unlink_port(struct device *port);
+#else
+static inline int typec_link_port(struct device *port)
+{
+ return 0;
+}
+
+static inline void typec_unlink_port(struct device *port) { }
+#endif
+
#endif /* __LINUX_USB_TYPEC_H */
--
2.30.2