diff --git a/drivers/bus/mhi/Kconfig b/drivers/bus/mhi/Kconfig
index e841c10..476cc55 100644
--- a/drivers/bus/mhi/Kconfig
+++ b/drivers/bus/mhi/Kconfig
@@ -20,3 +20,16 @@ config MHI_BUS_DEBUG
 	  Enable debugfs support for use with the MHI transport. Allows
 	  reading and/or modifying some values within the MHI controller
 	  for debug and test purposes.
+
+config MHI_UCI
+	tristate "MHI UCI"
+	depends on MHI_BUS
+	help
+	  MHI based Userspace Client Interface (UCI) driver is used for
+	  transferring raw data between host and device using standard file
+	  operations from userspace. Open, read, write, and close operations
+	  are supported by this driver. Please check mhi_uci_match_table for
+	  all supported channels that are exposed to userspace.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called mhi_uci.
diff --git a/drivers/bus/mhi/Makefile b/drivers/bus/mhi/Makefile
index 19e6443..80feefb 100644
--- a/drivers/bus/mhi/Makefile
+++ b/drivers/bus/mhi/Makefile
@@ -1,2 +1,6 @@
 # core layer
 obj-y += core/
+
+# MHI client
+mhi_uci-y := uci.o
+obj-$(CONFIG_MHI_UCI) += mhi_uci.o
diff --git a/drivers/bus/mhi/uci.c b/drivers/bus/mhi/uci.c
new file mode 100644
index 0000000..ea73c08
--- /dev/null
+++ b/drivers/bus/mhi/uci.c
@@ -0,0 +1,662 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2018-2020, The Linux Foundation. All rights reserved.*/
+
+#include <linux/kernel.h>
+#include <linux/mhi.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/poll.h>
+
+#define DEVICE_NAME "mhi"
+#define MHI_UCI_DRIVER_NAME "mhi_uci"
+#define MAX_UCI_MINORS 128
+
+static DEFINE_IDR(uci_idr);
+static DEFINE_MUTEX(uci_drv_mutex);
+static struct class *uci_dev_class;
+static int uci_dev_major;
+
+/**
+ * struct uci_chan - MHI channel for a UCI device
+ * @udev: associated UCI device object
+ * @ul_wq: wait queue for writer
+ * @write_lock: mutex write lock for ul channel
+ * @dl_wq: wait queue for reader
+ * @read_lock: mutex read lock for dl channel
+ * @dl_pending_lock: spin lock for dl_pending list
+ * @dl_pending: list of dl buffers userspace is waiting to read
+ * @cur_buf: current buffer userspace is reading
+ * @dl_size: size of the current dl buffer userspace is reading
+ * @ref_count: uci_chan reference count
+ */
+struct uci_chan {
+	struct uci_dev *udev;
+	wait_queue_head_t ul_wq;
+
+	/* ul channel lock to synchronize multiple writes */
+	struct mutex write_lock;
+
+	wait_queue_head_t dl_wq;
+
+	/* dl channel lock to synchronize multiple reads */
+	struct mutex read_lock;
+
+	/*
+	 * protects pending list in bh context, channel release, read and
+	 * poll
+	 */
+	spinlock_t dl_pending_lock;
+
+	struct list_head dl_pending;
+	struct uci_buf *cur_buf;
+	size_t dl_size;
+	struct kref ref_count;
+};
+
+/**
+ * struct uci_buf - UCI buffer
+ * @data: data buffer
+ * @len: length of data buffer
+ * @node: list node of the UCI buffer
+ */
+struct uci_buf {
+	void *data;
+	size_t len;
+	struct list_head node;
+};
+
+/**
+ * struct uci_dev - MHI UCI device
+ * @minor: UCI device node minor number
+ * @mhi_dev: associated mhi device object
+ * @uchan: UCI uplink and downlink channel object
+ * @mtu: max TRE buffer length
+ * @enabled: Flag to track the state of the UCI device
+ * @lock: mutex lock to manage uchan object
+ * @ref_count: uci_dev reference count
+ */
+struct uci_dev {
+	unsigned int minor;
+	struct mhi_device *mhi_dev;
+	struct uci_chan *uchan;
+	size_t mtu;
+	bool enabled;
+
+	/* synchronize open, release and driver remove */
+	struct mutex lock;
+	struct kref ref_count;
+};
+
+static void mhi_uci_dev_chan_release(struct kref *ref)
+{
+	struct uci_buf *buf_itr, *tmp;
+	struct uci_chan *uchan =
+		container_of(ref, struct uci_chan, ref_count);
+
+	if (uchan->udev->enabled)
+		mhi_unprepare_from_transfer(uchan->udev->mhi_dev);
+
+	spin_lock_bh(&uchan->dl_pending_lock);
+	list_for_each_entry_safe(buf_itr, tmp, &uchan->dl_pending, node) {
+		list_del(&buf_itr->node);
+		kfree(buf_itr->data);
+	}
+	spin_unlock_bh(&uchan->dl_pending_lock);
+
+	wake_up(&uchan->ul_wq);
+	wake_up(&uchan->dl_wq);
+
+	mutex_lock(&uchan->read_lock);
+	if (uchan->cur_buf)
+		kfree(uchan->cur_buf->data);
+
+	uchan->cur_buf = NULL;
+	mutex_unlock(&uchan->read_lock);
+
+	mutex_destroy(&uchan->write_lock);
+	mutex_destroy(&uchan->read_lock);
+
+	uchan->udev->uchan = NULL;
+	kfree(uchan);
+}
+
+static int mhi_queue_inbound(struct uci_dev *udev)
+{
+	struct mhi_device *mhi_dev = udev->mhi_dev;
+	struct device *dev = &mhi_dev->dev;
+	int nr_trbs, i, ret = -EIO;
+	size_t dl_buf_size;
+	void *buf;
+	struct uci_buf *ubuf;
+
+	/* dont queue if dl channel is not supported */
+	if (!udev->mhi_dev->dl_chan)
+		return 0;
+
+	nr_trbs = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
+
+	for (i = 0; i < nr_trbs; i++) {
+		buf = kmalloc(udev->mtu, GFP_KERNEL);
+		if (!buf)
+			return -ENOMEM;
+
+		dl_buf_size = udev->mtu - sizeof(*ubuf);
+
+		/* save uci_buf info at the end of buf */
+		ubuf = buf + dl_buf_size;
+		ubuf->data = buf;
+
+		dev_dbg(dev, "Allocated buf %d of %d size %zu\n", i, nr_trbs,
+			dl_buf_size);
+
+		ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, buf, dl_buf_size,
+				    MHI_EOT);
+		if (ret) {
+			kfree(buf);
+			dev_err(dev, "Failed to queue buffer %d\n", i);
+			return ret;
+		}
+	}
+
+	return ret;
+}
+
+static int mhi_uci_dev_start_chan(struct uci_dev *udev)
+{
+	int ret = 0;
+	struct uci_chan *uchan;
+
+	mutex_lock(&udev->lock);
+	if (!udev->uchan || !kref_get_unless_zero(&udev->uchan->ref_count)) {
+		uchan = kzalloc(sizeof(*uchan), GFP_KERNEL);
+		if (!uchan) {
+			ret = -ENOMEM;
+			goto error_chan_start;
+		}
+
+		udev->uchan = uchan;
+		uchan->udev = udev;
+		init_waitqueue_head(&uchan->ul_wq);
+		init_waitqueue_head(&uchan->dl_wq);
+		mutex_init(&uchan->write_lock);
+		mutex_init(&uchan->read_lock);
+		spin_lock_init(&uchan->dl_pending_lock);
+		INIT_LIST_HEAD(&uchan->dl_pending);
+
+		ret = mhi_prepare_for_transfer(udev->mhi_dev);
+		if (ret) {
+			dev_err(&udev->mhi_dev->dev, "Error starting transfer channels\n");
+			goto error_chan_cleanup;
+		}
+
+		ret = mhi_queue_inbound(udev);
+		if (ret)
+			goto error_chan_cleanup;
+
+		kref_init(&uchan->ref_count);
+	}
+
+	mutex_unlock(&udev->lock);
+
+	return 0;
+
+error_chan_cleanup:
+	mhi_uci_dev_chan_release(&uchan->ref_count);
+error_chan_start:
+	mutex_unlock(&udev->lock);
+	return ret;
+}
+
+static void mhi_uci_dev_release(struct kref *ref)
+{
+	struct uci_dev *udev =
+		container_of(ref, struct uci_dev, ref_count);
+
+	mutex_destroy(&udev->lock);
+
+	kfree(udev);
+}
+
+static int mhi_uci_open(struct inode *inode, struct file *filp)
+{
+	unsigned int minor = iminor(inode);
+	struct uci_dev *udev = NULL;
+	int ret;
+
+	mutex_lock(&uci_drv_mutex);
+	udev = idr_find(&uci_idr, minor);
+	if (!udev) {
+		pr_debug("uci dev: minor %d not found\n", minor);
+		mutex_unlock(&uci_drv_mutex);
+		return -ENODEV;
+	}
+
+	kref_get(&udev->ref_count);
+	mutex_unlock(&uci_drv_mutex);
+
+	ret = mhi_uci_dev_start_chan(udev);
+	if (ret) {
+		kref_put(&udev->ref_count, mhi_uci_dev_release);
+		return ret;
+	}
+
+	filp->private_data = udev;
+
+	return 0;
+}
+
+static int mhi_uci_release(struct inode *inode, struct file *file)
+{
+	struct uci_dev *udev = file->private_data;
+
+	mutex_lock(&udev->lock);
+	kref_put(&udev->uchan->ref_count, mhi_uci_dev_chan_release);
+	mutex_unlock(&udev->lock);
+
+	kref_put(&udev->ref_count, mhi_uci_dev_release);
+
+	return 0;
+}
+
+static __poll_t mhi_uci_poll(struct file *file, poll_table *wait)
+{
+	struct uci_dev *udev = file->private_data;
+	struct mhi_device *mhi_dev = udev->mhi_dev;
+	struct device *dev = &mhi_dev->dev;
+	struct uci_chan *uchan = udev->uchan;
+	__poll_t mask = 0;
+
+	poll_wait(file, &udev->uchan->ul_wq, wait);
+	poll_wait(file, &udev->uchan->dl_wq, wait);
+
+	if (!udev->enabled) {
+		mask = EPOLLERR;
+		goto done;
+	}
+
+	spin_lock_bh(&uchan->dl_pending_lock);
+	if (!list_empty(&uchan->dl_pending) || uchan->cur_buf) {
+		dev_dbg(dev, "Client can read from node\n");
+		mask |= EPOLLIN | EPOLLRDNORM;
+	}
+	spin_unlock_bh(&uchan->dl_pending_lock);
+
+	if (mhi_get_free_desc_count(mhi_dev, DMA_TO_DEVICE) > 0) {
+		dev_dbg(dev, "Client can write to node\n");
+		mask |= EPOLLOUT | EPOLLWRNORM;
+	}
+
+	dev_dbg(dev, "Client attempted to poll, returning mask 0x%x\n", mask);
+
+done:
+	return mask;
+}
+
+static ssize_t mhi_uci_write(struct file *file,
+			     const char __user *buf,
+			     size_t count,
+			     loff_t *offp)
+{
+	struct uci_dev *udev = file->private_data;
+	struct mhi_device *mhi_dev = udev->mhi_dev;
+	struct device *dev = &mhi_dev->dev;
+	struct uci_chan *uchan = udev->uchan;
+	size_t bytes_xfered = 0;
+	int ret, nr_avail = 0;
+
+	/* if ul channel is not supported return error */
+	if (!buf || !count || !mhi_dev->ul_chan)
+		return -EINVAL;
+
+	dev_dbg(dev, "%s: to xfer: %zu bytes\n", __func__, count);
+
+	if (mutex_lock_interruptible(&uchan->write_lock))
+		return -EINTR;
+
+	while (count) {
+		size_t xfer_size;
+		void *kbuf;
+		enum mhi_flags flags;
+
+		/* wait for free descriptors */
+		ret = wait_event_interruptible(uchan->ul_wq,
+					       (!udev->enabled) ||
+				(nr_avail = mhi_get_free_desc_count(mhi_dev,
+					       DMA_TO_DEVICE)) > 0);
+
+		if (ret == -ERESTARTSYS) {
+			dev_dbg(dev, "Interrupted by a signal in %s, exiting\n",
+				__func__);
+			goto err_mtx_unlock;
+		}
+
+		if (!udev->enabled) {
+			ret = -ENODEV;
+			goto err_mtx_unlock;
+		}
+
+		xfer_size = min_t(size_t, count, udev->mtu);
+		kbuf = kmalloc(xfer_size, GFP_KERNEL);
+		if (!kbuf) {
+			ret = -ENOMEM;
+			goto err_mtx_unlock;
+		}
+
+		ret = copy_from_user(kbuf, buf, xfer_size);
+		if (ret) {
+			kfree(kbuf);
+			ret = -EFAULT;
+			goto err_mtx_unlock;
+		}
+
+		/* if ring is full after this force EOT */
+		if (nr_avail > 1 && (count - xfer_size))
+			flags = MHI_CHAIN;
+		else
+			flags = MHI_EOT;
+
+		ret = mhi_queue_buf(mhi_dev, DMA_TO_DEVICE, kbuf, xfer_size,
+				    flags);
+		if (ret) {
+			kfree(kbuf);
+			goto err_mtx_unlock;
+		}
+
+		bytes_xfered += xfer_size;
+		count -= xfer_size;
+		buf += xfer_size;
+	}
+
+	mutex_unlock(&uchan->write_lock);
+	dev_dbg(dev, "%s: bytes xferred: %zu\n", __func__, bytes_xfered);
+
+	return bytes_xfered;
+
+err_mtx_unlock:
+	mutex_unlock(&uchan->write_lock);
+
+	return ret;
+}
+
+static ssize_t mhi_uci_read(struct file *file,
+			    char __user *buf,
+			    size_t count,
+			    loff_t *ppos)
+{
+	struct uci_dev *udev = file->private_data;
+	struct mhi_device *mhi_dev = udev->mhi_dev;
+	struct uci_chan *uchan = udev->uchan;
+	struct device *dev = &mhi_dev->dev;
+	struct uci_buf *ubuf;
+	size_t rx_buf_size;
+	char *ptr;
+	size_t to_copy;
+	int ret = 0;
+
+	/* if dl channel is not supported return error */
+	if (!buf || !mhi_dev->dl_chan)
+		return -EINVAL;
+
+	if (mutex_lock_interruptible(&uchan->read_lock))
+		return -EINTR;
+
+	spin_lock_bh(&uchan->dl_pending_lock);
+	/* No data available to read, wait */
+	if (!uchan->cur_buf && list_empty(&uchan->dl_pending)) {
+		dev_dbg(dev, "No data available to read, waiting\n");
+
+		spin_unlock_bh(&uchan->dl_pending_lock);
+		ret = wait_event_interruptible(uchan->dl_wq,
+					       (!udev->enabled ||
+					      !list_empty(&uchan->dl_pending)));
+
+		if (ret == -ERESTARTSYS) {
+			dev_dbg(dev, "Interrupted by a signal in %s, exiting\n",
+				__func__);
+			goto err_mtx_unlock;
+		}
+
+		if (!udev->enabled) {
+			ret = -ENODEV;
+			goto err_mtx_unlock;
+		}
+		spin_lock_bh(&uchan->dl_pending_lock);
+	}
+
+	/* new read, get the next descriptor from the list */
+	if (!uchan->cur_buf) {
+		ubuf = list_first_entry_or_null(&uchan->dl_pending,
+						struct uci_buf, node);
+		if (!ubuf) {
+			ret = -EIO;
+			goto err_spin_unlock;
+		}
+
+		list_del(&ubuf->node);
+		uchan->cur_buf = ubuf;
+		uchan->dl_size = ubuf->len;
+		dev_dbg(dev, "Got pkt of size: %zu\n", uchan->dl_size);
+	}
+	spin_unlock_bh(&uchan->dl_pending_lock);
+
+	ubuf = uchan->cur_buf;
+
+	/* Copy the buffer to user space */
+	to_copy = min_t(size_t, count, uchan->dl_size);
+	ptr = ubuf->data + (ubuf->len - uchan->dl_size);
+
+	ret = copy_to_user(buf, ptr, to_copy);
+	if (ret) {
+		ret = -EFAULT;
+		goto err_mtx_unlock;
+	}
+
+	dev_dbg(dev, "Copied %zu of %zu bytes\n", to_copy, uchan->dl_size);
+	uchan->dl_size -= to_copy;
+
+	/* we finished with this buffer, queue it back to hardware */
+	if (!uchan->dl_size) {
+		uchan->cur_buf = NULL;
+
+		rx_buf_size = udev->mtu - sizeof(*ubuf);
+		ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, ubuf->data,
+				    rx_buf_size, MHI_EOT);
+		if (ret) {
+			dev_err(dev, "Failed to recycle element: %d\n", ret);
+			kfree(ubuf->data);
+			goto err_mtx_unlock;
+		}
+	}
+	mutex_unlock(&uchan->read_lock);
+
+	dev_dbg(dev, "%s: Returning %zu bytes\n", __func__, to_copy);
+
+	return to_copy;
+
+err_spin_unlock:
+	spin_unlock_bh(&uchan->dl_pending_lock);
+err_mtx_unlock:
+	mutex_unlock(&uchan->read_lock);
+	return ret;
+}
+
+static const struct file_operations mhidev_fops = {
+	.owner = THIS_MODULE,
+	.open = mhi_uci_open,
+	.release = mhi_uci_release,
+	.read = mhi_uci_read,
+	.write = mhi_uci_write,
+	.poll = mhi_uci_poll,
+};
+
+static void mhi_ul_xfer_cb(struct mhi_device *mhi_dev,
+			   struct mhi_result *mhi_result)
+{
+	struct uci_dev *udev = dev_get_drvdata(&mhi_dev->dev);
+	struct uci_chan *uchan = udev->uchan;
+	struct device *dev = &mhi_dev->dev;
+
+	dev_dbg(dev, "status: %d xfer_len: %zu\n",
+		mhi_result->transaction_status, mhi_result->bytes_xferd);
+
+	kfree(mhi_result->buf_addr);
+
+	if (!mhi_result->transaction_status)
+		wake_up(&uchan->ul_wq);
+}
+
+static void mhi_dl_xfer_cb(struct mhi_device *mhi_dev,
+			   struct mhi_result *mhi_result)
+{
+	struct uci_dev *udev = dev_get_drvdata(&mhi_dev->dev);
+	struct uci_chan *uchan = udev->uchan;
+	struct device *dev = &mhi_dev->dev;
+	struct uci_buf *ubuf;
+	size_t dl_buf_size = udev->mtu - sizeof(*ubuf);
+
+	dev_dbg(dev, "status: %d receive_len: %zu\n",
+		mhi_result->transaction_status, mhi_result->bytes_xferd);
+
+	if (mhi_result->transaction_status &&
+	    mhi_result->transaction_status != -EOVERFLOW) {
+		kfree(mhi_result->buf_addr);
+		return;
+	}
+
+	ubuf = mhi_result->buf_addr + dl_buf_size;
+	ubuf->data = mhi_result->buf_addr;
+	ubuf->len = mhi_result->bytes_xferd;
+	spin_lock_bh(&uchan->dl_pending_lock);
+	list_add_tail(&ubuf->node, &uchan->dl_pending);
+	spin_unlock_bh(&uchan->dl_pending_lock);
+
+	wake_up(&uchan->dl_wq);
+}
+
+static int mhi_uci_probe(struct mhi_device *mhi_dev,
+			 const struct mhi_device_id *id)
+{
+	struct uci_dev *udev;
+	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
+	struct device *dev;
+	int index;
+
+	udev = kzalloc(sizeof(*udev), GFP_KERNEL);
+	if (!udev)
+		return -ENOMEM;
+
+	kref_init(&udev->ref_count);
+	mutex_init(&udev->lock);
+	udev->mhi_dev = mhi_dev;
+
+	mutex_lock(&uci_drv_mutex);
+	index = idr_alloc(&uci_idr, udev, 0, MAX_UCI_MINORS, GFP_KERNEL);
+	mutex_unlock(&uci_drv_mutex);
+	if (index < 0) {
+		kfree(udev);
+		return index;
+	}
+
+	udev->minor = index;
+
+	udev->mtu = min_t(size_t, id->driver_data, MHI_MAX_MTU);
+	dev_set_drvdata(&mhi_dev->dev, udev);
+	udev->enabled = true;
+
+	/* create device file node /dev/mhi_<cntrl_dev_name>_<mhi_dev_name> */
+	dev = device_create(uci_dev_class, &mhi_dev->dev,
+			    MKDEV(uci_dev_major, index), udev,
+			    DEVICE_NAME "_%s_%s",
+			    dev_name(mhi_cntrl->cntrl_dev), mhi_dev->name);
+	if (IS_ERR(dev)) {
+		mutex_lock(&uci_drv_mutex);
+		idr_remove(&uci_idr, udev->minor);
+		mutex_unlock(&uci_drv_mutex);
+		dev_set_drvdata(&mhi_dev->dev, NULL);
+		kfree(udev);
+		return PTR_ERR(dev);
+	}
+
+	dev_dbg(&mhi_dev->dev, "probed uci dev: %s\n", id->chan);
+
+	return 0;
+};
+
+static void mhi_uci_remove(struct mhi_device *mhi_dev)
+{
+	struct uci_dev *udev = dev_get_drvdata(&mhi_dev->dev);
+
+	/* disable the node */
+	mutex_lock(&udev->lock);
+	udev->enabled = false;
+
+	/* delete the node to prevent new opens */
+	device_destroy(uci_dev_class, MKDEV(uci_dev_major, udev->minor));
+
+	/* return error for any blocked read or write */
+	if (udev->uchan) {
+		wake_up(&udev->uchan->ul_wq);
+		wake_up(&udev->uchan->dl_wq);
+	}
+	mutex_unlock(&udev->lock);
+
+	mutex_lock(&uci_drv_mutex);
+	idr_remove(&uci_idr, udev->minor);
+	kref_put(&udev->ref_count, mhi_uci_dev_release);
+	mutex_unlock(&uci_drv_mutex);
+}
+
+/* .driver_data stores max mtu */
+static const struct mhi_device_id mhi_uci_match_table[] = {
+	{ .chan = "LOOPBACK", .driver_data = 0x1000},
+	{},
+};
+MODULE_DEVICE_TABLE(mhi, mhi_uci_match_table);
+
+static struct mhi_driver mhi_uci_driver = {
+	.id_table = mhi_uci_match_table,
+	.remove = mhi_uci_remove,
+	.probe = mhi_uci_probe,
+	.ul_xfer_cb = mhi_ul_xfer_cb,
+	.dl_xfer_cb = mhi_dl_xfer_cb,
+	.driver = {
+		.name = MHI_UCI_DRIVER_NAME,
+	},
+};
+
+static int __init mhi_uci_init(void)
+{
+	int ret;
+
+	ret = register_chrdev(0, MHI_UCI_DRIVER_NAME, &mhidev_fops);
+	if (ret < 0)
+		return ret;
+
+	uci_dev_major = ret;
+	uci_dev_class = class_create(THIS_MODULE, MHI_UCI_DRIVER_NAME);
+	if (IS_ERR(uci_dev_class)) {
+		unregister_chrdev(uci_dev_major, MHI_UCI_DRIVER_NAME);
+		return PTR_ERR(uci_dev_class);
+	}
+
+	ret = mhi_driver_register(&mhi_uci_driver);
+	if (ret) {
+		class_destroy(uci_dev_class);
+		unregister_chrdev(uci_dev_major, MHI_UCI_DRIVER_NAME);
+	}
+
+	return ret;
+}
+
+static void __exit mhi_uci_exit(void)
+{
+	mhi_driver_unregister(&mhi_uci_driver);
+	class_destroy(uci_dev_class);
+	unregister_chrdev(uci_dev_major, MHI_UCI_DRIVER_NAME);
+	idr_destroy(&uci_idr);
+}
+
+module_init(mhi_uci_init);
+module_exit(mhi_uci_exit);
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MHI UCI Driver");
