Fixed MTP to work with TWRP

drivers/iommu/iommu-sysfs.c

@@ -0,0 +1,134 @@
+/*
+ * IOMMU sysfs class support
+ *
+ * Copyright (C) 2014 Red Hat, Inc.  All rights reserved.
+ *     Author: Alex Williamson <alex.williamson@redhat.com>
+ *
+ * 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.
+ */
+
+#include <linux/device.h>
+#include <linux/iommu.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+/*
+ * We provide a common class "devices" group which initially has no attributes.
+ * As devices are added to the IOMMU, we'll add links to the group.
+ */
+static struct attribute *devices_attr[] = {
+	NULL,
+};
+
+static const struct attribute_group iommu_devices_attr_group = {
+	.name = "devices",
+	.attrs = devices_attr,
+};
+
+static const struct attribute_group *iommu_dev_groups[] = {
+	&iommu_devices_attr_group,
+	NULL,
+};
+
+static void iommu_release_device(struct device *dev)
+{
+	kfree(dev);
+}
+
+static struct class iommu_class = {
+	.name = "iommu",
+	.dev_release = iommu_release_device,
+	.dev_groups = iommu_dev_groups,
+};
+
+static int __init iommu_dev_init(void)
+{
+	return class_register(&iommu_class);
+}
+postcore_initcall(iommu_dev_init);
+
+/*
+ * Create an IOMMU device and return a pointer to it.  IOMMU specific
+ * attributes can be provided as an attribute group, allowing a unique
+ * namespace per IOMMU type.
+ */
+struct device *iommu_device_create(struct device *parent, void *drvdata,
+				   const struct attribute_group **groups,
+				   const char *fmt, ...)
+{
+	struct device *dev;
+	va_list vargs;
+	int ret;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return ERR_PTR(-ENOMEM);
+
+	device_initialize(dev);
+
+	dev->class = &iommu_class;
+	dev->parent = parent;
+	dev->groups = groups;
+	dev_set_drvdata(dev, drvdata);
+
+	va_start(vargs, fmt);
+	ret = kobject_set_name_vargs(&dev->kobj, fmt, vargs);
+	va_end(vargs);
+	if (ret)
+		goto error;
+
+	ret = device_add(dev);
+	if (ret)
+		goto error;
+
+	return dev;
+
+error:
+	put_device(dev);
+	return ERR_PTR(ret);
+}
+
+void iommu_device_destroy(struct device *dev)
+{
+	if (!dev || IS_ERR(dev))
+		return;
+
+	device_unregister(dev);
+}
+
+/*
+ * IOMMU drivers can indicate a device is managed by a given IOMMU using
+ * this interface.  A link to the device will be created in the "devices"
+ * directory of the IOMMU device in sysfs and an "iommu" link will be
+ * created under the linked device, pointing back at the IOMMU device.
+ */
+int iommu_device_link(struct device *dev, struct device *link)
+{
+	int ret;
+
+	if (!dev || IS_ERR(dev))
+		return -ENODEV;
+
+	ret = sysfs_add_link_to_group(&dev->kobj, "devices",
+				      &link->kobj, dev_name(link));
+	if (ret)
+		return ret;
+
+	ret = sysfs_create_link_nowarn(&link->kobj, &dev->kobj, "iommu");
+	if (ret)
+		sysfs_remove_link_from_group(&dev->kobj, "devices",
+					     dev_name(link));
+
+	return ret;
+}
+
+void iommu_device_unlink(struct device *dev, struct device *link)
+{
+	if (!dev || IS_ERR(dev))
+		return;
+
+	sysfs_remove_link(&link->kobj, "iommu");
+	sysfs_remove_link_from_group(&dev->kobj, "devices", dev_name(link));
+}