To recover from this mode, one needs to flash a valid NVM image to the
host host controller in the same way it is done in the previous chapter.
+
+Forcing power
+-------------
+Many OEMs include a method that can be used to force the power of a
+thunderbolt controller to an "On" state even if nothing is connected.
+If supported by your machine this will be exposed by the WMI bus with
+a sysfs attribute called "force_power".
+
+For example the intel-wmi-thunderbolt driver exposes this attribute in:
+ /sys/devices/platform/PNP0C14:00/wmi_bus/wmi_bus-PNP0C14:00/86CCFD48-205E-4A77-9C48-2021CBEDE341/force_power
+
+ To force the power to on, write 1 to this attribute file.
+ To disable force power, write 0 to this attribute file.
+
+Note: it's currently not possible to query the force power state of a platform.
--- /dev/null
+/*
+ * WMI Thunderbolt driver
+ *
+ * Copyright (C) 2017 Dell Inc. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/acpi.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+#include <linux/wmi.h>
+
+#define INTEL_WMI_THUNDERBOLT_GUID "86CCFD48-205E-4A77-9C48-2021CBEDE341"
+
+static ssize_t force_power_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct acpi_buffer input;
+ acpi_status status;
+ u8 mode;
+
+ input.length = sizeof(u8);
+ input.pointer = &mode;
+ mode = hex_to_bin(buf[0]);
+ if (mode == 0 || mode == 1) {
+ status = wmi_evaluate_method(INTEL_WMI_THUNDERBOLT_GUID, 0, 1,
+ &input, NULL);
+ if (ACPI_FAILURE(status)) {
+ pr_err("intel-wmi-thunderbolt: failed setting %s\n",
+ buf);
+ return -ENODEV;
+ }
+ } else {
+ pr_err("intel-wmi-thunderbolt: unsupported mode: %d", mode);
+ }
+ return count;
+}
+
+static DEVICE_ATTR_WO(force_power);
+
+static struct attribute *tbt_attrs[] = {
+ &dev_attr_force_power.attr,
+ NULL
+};
+
+static const struct attribute_group tbt_attribute_group = {
+ .attrs = tbt_attrs,
+};
+
+static int intel_wmi_thunderbolt_probe(struct wmi_device *wdev)
+{
+ int ret;
+
+ ret = sysfs_create_group(&wdev->dev.kobj, &tbt_attribute_group);
+ kobject_uevent(&wdev->dev.kobj, KOBJ_CHANGE);
+ return ret;
+}
+
+static int intel_wmi_thunderbolt_remove(struct wmi_device *wdev)
+{
+ sysfs_remove_group(&wdev->dev.kobj, &tbt_attribute_group);
+ kobject_uevent(&wdev->dev.kobj, KOBJ_CHANGE);
+ return 0;
+}
+
+static const struct wmi_device_id intel_wmi_thunderbolt_id_table[] = {
+ { .guid_string = INTEL_WMI_THUNDERBOLT_GUID },
+ { },
+};
+
+static struct wmi_driver intel_wmi_thunderbolt_driver = {
+ .driver = {
+ .name = "intel-wmi-thunderbolt",
+ },
+ .probe = intel_wmi_thunderbolt_probe,
+ .remove = intel_wmi_thunderbolt_remove,
+ .id_table = intel_wmi_thunderbolt_id_table,
+};
+
+module_wmi_driver(intel_wmi_thunderbolt_driver);
+
+MODULE_ALIAS("wmi:" INTEL_WMI_THUNDERBOLT_GUID);
+MODULE_AUTHOR("Mario Limonciello <mario.limonciello@dell.com>");
+MODULE_DESCRIPTION("Intel WMI Thunderbolt force power driver");
+MODULE_LICENSE("GPL");
projects / linux.git / commitdiff