thunderbolt: Add support for retimer NVM upgrade when there is no link

With help from platform firmware (ACPI) it is possible to power on
retimers even when there is no USB4 link (e.g nothing is connected to
the USB4 ports). This allows us to bring the USB4 sideband up so that we
can access retimers and upgrade their NVM firmware.

If the platform has support for this, we expose two additional
attributes under USB4 ports: offline and rescan. These can be used to
bring the port offline, rescan for the retimers and put the port online
again. The retimer NVM upgrade itself works the same way than with cable
connected.

Signed-off-by: Rajmohan Mani <rajmohan.mani@intel.com>
Co-developed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 169 insertions, 0 deletions

diff --git a/drivers/thunderbolt/usb4_port.c b/drivers/thunderbolt/usb4_port.c
index 520bbfd7bf33..765c74179598 100644
--- a/drivers/thunderbolt/usb4_port.c
+++ b/drivers/thunderbolt/usb4_port.c
@@ -44,8 +44,166 @@ static const struct attribute_group common_group = {
 	.attrs = common_attrs,
 };
 
+static int usb4_port_offline(struct usb4_port *usb4)
+{
+	struct tb_port *port = usb4->port;
+	int ret;
+
+	ret = tb_acpi_power_on_retimers(port);
+	if (ret)
+		return ret;
+
+	ret = usb4_port_router_offline(port);
+	if (ret) {
+		tb_acpi_power_off_retimers(port);
+		return ret;
+	}
+
+	ret = tb_retimer_scan(port, false);
+	if (ret) {
+		usb4_port_router_online(port);
+		tb_acpi_power_off_retimers(port);
+	}
+
+	return ret;
+}
+
+static void usb4_port_online(struct usb4_port *usb4)
+{
+	struct tb_port *port = usb4->port;
+
+	usb4_port_router_online(port);
+	tb_acpi_power_off_retimers(port);
+}
+
+static ssize_t offline_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	struct usb4_port *usb4 = tb_to_usb4_port_device(dev);
+
+	return sysfs_emit(buf, "%d\n", usb4->offline);
+}
+
+static ssize_t offline_store(struct device *dev,
+	struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct usb4_port *usb4 = tb_to_usb4_port_device(dev);
+	struct tb_port *port = usb4->port;
+	struct tb *tb = port->sw->tb;
+	bool val;
+	int ret;
+
+	ret = kstrtobool(buf, &val);
+	if (ret)
+		return ret;
+
+	pm_runtime_get_sync(&usb4->dev);
+
+	if (mutex_lock_interruptible(&tb->lock)) {
+		ret = -ERESTARTSYS;
+		goto out_rpm;
+	}
+
+	if (val == usb4->offline)
+		goto out_unlock;
+
+	/* Offline mode works only for ports that are not connected */
+	if (tb_port_has_remote(port)) {
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+
+	if (val) {
+		ret = usb4_port_offline(usb4);
+		if (ret)
+			goto out_unlock;
+	} else {
+		usb4_port_online(usb4);
+		tb_retimer_remove_all(port);
+	}
+
+	usb4->offline = val;
+	tb_port_dbg(port, "%s offline mode\n", val ? "enter" : "exit");
+
+out_unlock:
+	mutex_unlock(&tb->lock);
+out_rpm:
+	pm_runtime_mark_last_busy(&usb4->dev);
+	pm_runtime_put_autosuspend(&usb4->dev);
+
+	return ret ? ret : count;
+}
+static DEVICE_ATTR_RW(offline);
+
+static ssize_t rescan_store(struct device *dev,
+	struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct usb4_port *usb4 = tb_to_usb4_port_device(dev);
+	struct tb_port *port = usb4->port;
+	struct tb *tb = port->sw->tb;
+	bool val;
+	int ret;
+
+	ret = kstrtobool(buf, &val);
+	if (ret)
+		return ret;
+
+	if (!val)
+		return count;
+
+	pm_runtime_get_sync(&usb4->dev);
+
+	if (mutex_lock_interruptible(&tb->lock)) {
+		ret = -ERESTARTSYS;
+		goto out_rpm;
+	}
+
+	/* Must be in offline mode already */
+	if (!usb4->offline) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	tb_retimer_remove_all(port);
+	ret = tb_retimer_scan(port, true);
+
+out_unlock:
+	mutex_unlock(&tb->lock);
+out_rpm:
+	pm_runtime_mark_last_busy(&usb4->dev);
+	pm_runtime_put_autosuspend(&usb4->dev);
+
+	return ret ? ret : count;
+}
+static DEVICE_ATTR_WO(rescan);
+
+static struct attribute *service_attrs[] = {
+	&dev_attr_offline.attr,
+	&dev_attr_rescan.attr,
+	NULL
+};
+
+static umode_t service_attr_is_visible(struct kobject *kobj,
+				       struct attribute *attr, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct usb4_port *usb4 = tb_to_usb4_port_device(dev);
+
+	/*
+	 * Always need some platform help to cycle the modes so that
+	 * retimers can be accessed through the sideband.
+	 */
+	return usb4->can_offline ? attr->mode : 0;
+}
+
+static const struct attribute_group service_group = {
+	.attrs = service_attrs,
+	.is_visible = service_attr_is_visible,
+};
+
 static const struct attribute_group *usb4_port_device_groups[] = {
 	&common_group,
+	&service_group,
 	NULL
 };
 
@@ -110,3 +268,14 @@ void usb4_port_device_remove(struct usb4_port *usb4)
 {
 	device_unregister(&usb4->dev);
 }
+
+/**
+ * usb4_port_device_resume() - Resumes USB4 port device
+ * @usb4: USB4 port device
+ *
+ * Used to resume USB4 port device after sleep state.
+ */
+int usb4_port_device_resume(struct usb4_port *usb4)
+{
+	return usb4->offline ? usb4_port_offline(usb4) : 0;
+}