thunderbolt: Add USB4 port devices

Create devices for each USB4 port. This is needed when we add retimer
access when there is no device connected but may be useful for other
purposes too following what USB subsystem does. This exports a single
attribute "link" that shows the type of the USB4 link (or "none" if
there is no cable connected).

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 112 insertions, 0 deletions

diff --git a/drivers/thunderbolt/usb4_port.c b/drivers/thunderbolt/usb4_port.c
new file mode 100644
index 000000000000..520bbfd7bf33
--- /dev/null
+++ b/drivers/thunderbolt/usb4_port.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * USB4 port device
+ *
+ * Copyright (C) 2021, Intel Corporation
+ * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/pm_runtime.h>
+
+#include "tb.h"
+
+static ssize_t link_show(struct device *dev, struct device_attribute *attr,
+			 char *buf)
+{
+	struct usb4_port *usb4 = tb_to_usb4_port_device(dev);
+	struct tb_port *port = usb4->port;
+	struct tb *tb = port->sw->tb;
+	const char *link;
+
+	if (mutex_lock_interruptible(&tb->lock))
+		return -ERESTARTSYS;
+
+	if (tb_is_upstream_port(port))
+		link = port->sw->link_usb4 ? "usb4" : "tbt";
+	else if (tb_port_has_remote(port))
+		link = port->remote->sw->link_usb4 ? "usb4" : "tbt";
+	else
+		link = "none";
+
+	mutex_unlock(&tb->lock);
+
+	return sysfs_emit(buf, "%s\n", link);
+}
+static DEVICE_ATTR_RO(link);
+
+static struct attribute *common_attrs[] = {
+	&dev_attr_link.attr,
+	NULL
+};
+
+static const struct attribute_group common_group = {
+	.attrs = common_attrs,
+};
+
+static const struct attribute_group *usb4_port_device_groups[] = {
+	&common_group,
+	NULL
+};
+
+static void usb4_port_device_release(struct device *dev)
+{
+	struct usb4_port *usb4 = container_of(dev, struct usb4_port, dev);
+
+	kfree(usb4);
+}
+
+struct device_type usb4_port_device_type = {
+	.name = "usb4_port",
+	.groups = usb4_port_device_groups,
+	.release = usb4_port_device_release,
+};
+
+/**
+ * usb4_port_device_add() - Add USB4 port device
+ * @port: Lane 0 adapter port to add the USB4 port
+ *
+ * Creates and registers a USB4 port device for @port. Returns the new
+ * USB4 port device pointer or ERR_PTR() in case of error.
+ */
+struct usb4_port *usb4_port_device_add(struct tb_port *port)
+{
+	struct usb4_port *usb4;
+	int ret;
+
+	usb4 = kzalloc(sizeof(*usb4), GFP_KERNEL);
+	if (!usb4)
+		return ERR_PTR(-ENOMEM);
+
+	usb4->port = port;
+	usb4->dev.type = &usb4_port_device_type;
+	usb4->dev.parent = &port->sw->dev;
+	dev_set_name(&usb4->dev, "usb4_port%d", port->port);
+
+	ret = device_register(&usb4->dev);
+	if (ret) {
+		put_device(&usb4->dev);
+		return ERR_PTR(ret);
+	}
+
+	pm_runtime_no_callbacks(&usb4->dev);
+	pm_runtime_set_active(&usb4->dev);
+	pm_runtime_enable(&usb4->dev);
+	pm_runtime_set_autosuspend_delay(&usb4->dev, TB_AUTOSUSPEND_DELAY);
+	pm_runtime_mark_last_busy(&usb4->dev);
+	pm_runtime_use_autosuspend(&usb4->dev);
+
+	return usb4;
+}
+
+/**
+ * usb4_port_device_remove() - Removes USB4 port device
+ * @usb4: USB4 port device
+ *
+ * Unregisters the USB4 port device from the system. The device will be
+ * released when the last reference is dropped.
+ */
+void usb4_port_device_remove(struct usb4_port *usb4)
+{
+	device_unregister(&usb4->dev);
+}