v4.19.13 snapshot.
diff --git a/net/qrtr/tun.c b/net/qrtr/tun.c
new file mode 100644
index 0000000..ccff1e5
--- /dev/null
+++ b/net/qrtr/tun.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2018, Linaro Ltd */
+
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/poll.h>
+#include <linux/skbuff.h>
+#include <linux/uaccess.h>
+
+#include "qrtr.h"
+
+struct qrtr_tun {
+ struct qrtr_endpoint ep;
+
+ struct sk_buff_head queue;
+ wait_queue_head_t readq;
+};
+
+static int qrtr_tun_send(struct qrtr_endpoint *ep, struct sk_buff *skb)
+{
+ struct qrtr_tun *tun = container_of(ep, struct qrtr_tun, ep);
+
+ skb_queue_tail(&tun->queue, skb);
+
+ /* wake up any blocking processes, waiting for new data */
+ wake_up_interruptible(&tun->readq);
+
+ return 0;
+}
+
+static int qrtr_tun_open(struct inode *inode, struct file *filp)
+{
+ struct qrtr_tun *tun;
+
+ tun = kzalloc(sizeof(*tun), GFP_KERNEL);
+ if (!tun)
+ return -ENOMEM;
+
+ skb_queue_head_init(&tun->queue);
+ init_waitqueue_head(&tun->readq);
+
+ tun->ep.xmit = qrtr_tun_send;
+
+ filp->private_data = tun;
+
+ return qrtr_endpoint_register(&tun->ep, QRTR_EP_NID_AUTO);
+}
+
+static ssize_t qrtr_tun_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+ struct file *filp = iocb->ki_filp;
+ struct qrtr_tun *tun = filp->private_data;
+ struct sk_buff *skb;
+ int count;
+
+ while (!(skb = skb_dequeue(&tun->queue))) {
+ if (filp->f_flags & O_NONBLOCK)
+ return -EAGAIN;
+
+ /* Wait until we get data or the endpoint goes away */
+ if (wait_event_interruptible(tun->readq,
+ !skb_queue_empty(&tun->queue)))
+ return -ERESTARTSYS;
+ }
+
+ count = min_t(size_t, iov_iter_count(to), skb->len);
+ if (copy_to_iter(skb->data, count, to) != count)
+ count = -EFAULT;
+
+ kfree_skb(skb);
+
+ return count;
+}
+
+static ssize_t qrtr_tun_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+ struct file *filp = iocb->ki_filp;
+ struct qrtr_tun *tun = filp->private_data;
+ size_t len = iov_iter_count(from);
+ ssize_t ret;
+ void *kbuf;
+
+ kbuf = kzalloc(len, GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+
+ if (!copy_from_iter_full(kbuf, len, from))
+ return -EFAULT;
+
+ ret = qrtr_endpoint_post(&tun->ep, kbuf, len);
+
+ return ret < 0 ? ret : len;
+}
+
+static __poll_t qrtr_tun_poll(struct file *filp, poll_table *wait)
+{
+ struct qrtr_tun *tun = filp->private_data;
+ __poll_t mask = 0;
+
+ poll_wait(filp, &tun->readq, wait);
+
+ if (!skb_queue_empty(&tun->queue))
+ mask |= EPOLLIN | EPOLLRDNORM;
+
+ return mask;
+}
+
+static int qrtr_tun_release(struct inode *inode, struct file *filp)
+{
+ struct qrtr_tun *tun = filp->private_data;
+ struct sk_buff *skb;
+
+ qrtr_endpoint_unregister(&tun->ep);
+
+ /* Discard all SKBs */
+ while (!skb_queue_empty(&tun->queue)) {
+ skb = skb_dequeue(&tun->queue);
+ kfree_skb(skb);
+ }
+
+ kfree(tun);
+
+ return 0;
+}
+
+static const struct file_operations qrtr_tun_ops = {
+ .owner = THIS_MODULE,
+ .open = qrtr_tun_open,
+ .poll = qrtr_tun_poll,
+ .read_iter = qrtr_tun_read_iter,
+ .write_iter = qrtr_tun_write_iter,
+ .release = qrtr_tun_release,
+};
+
+static struct miscdevice qrtr_tun_miscdev = {
+ MISC_DYNAMIC_MINOR,
+ "qrtr-tun",
+ &qrtr_tun_ops,
+};
+
+static int __init qrtr_tun_init(void)
+{
+ int ret;
+
+ ret = misc_register(&qrtr_tun_miscdev);
+ if (ret)
+ pr_err("failed to register Qualcomm IPC Router tun device\n");
+
+ return ret;
+}
+
+static void __exit qrtr_tun_exit(void)
+{
+ misc_deregister(&qrtr_tun_miscdev);
+}
+
+module_init(qrtr_tun_init);
+module_exit(qrtr_tun_exit);
+
+MODULE_DESCRIPTION("Qualcomm IPC Router TUN device");
+MODULE_LICENSE("GPL v2");