This MHI client driver allows userspace clients to transfer
raw data between MHI device and host using standard file operations.
Device file node is created with format

/dev/mhi_<controller_name>_<mhi_device_name>

Currently it supports LOOPBACK channel.

Signed-off-by: Hemant Kumar <hema...@codeaurora.org>
---
 drivers/bus/mhi/Kconfig          |   6 +
 drivers/bus/mhi/Makefile         |   1 +
 drivers/bus/mhi/clients/Kconfig  |  15 +
 drivers/bus/mhi/clients/Makefile |   3 +
 drivers/bus/mhi/clients/uci.c    | 662 +++++++++++++++++++++++++++++++++++++++
 5 files changed, 687 insertions(+)
 create mode 100644 drivers/bus/mhi/clients/Kconfig
 create mode 100644 drivers/bus/mhi/clients/Makefile
 create mode 100644 drivers/bus/mhi/clients/uci.c

diff --git a/drivers/bus/mhi/Kconfig b/drivers/bus/mhi/Kconfig
index 6a217ff..927c392 100644
--- a/drivers/bus/mhi/Kconfig
+++ b/drivers/bus/mhi/Kconfig
@@ -20,3 +20,9 @@ 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.
+
+if MHI_BUS
+
+source "drivers/bus/mhi/clients/Kconfig"
+
+endif
diff --git a/drivers/bus/mhi/Makefile b/drivers/bus/mhi/Makefile
index 19e6443..48f6028 100644
--- a/drivers/bus/mhi/Makefile
+++ b/drivers/bus/mhi/Makefile
@@ -1,2 +1,3 @@
 # core layer
 obj-y += core/
+obj-y += clients/
diff --git a/drivers/bus/mhi/clients/Kconfig b/drivers/bus/mhi/clients/Kconfig
new file mode 100644
index 0000000..37aaf51
--- /dev/null
+++ b/drivers/bus/mhi/clients/Kconfig
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+menu "MHI clients support"
+
+config MHI_UCI
+       tristate "MHI UCI"
+       depends on MHI_BUS
+       help
+        MHI based userspace client interface 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.
+
+endmenu
diff --git a/drivers/bus/mhi/clients/Makefile b/drivers/bus/mhi/clients/Makefile
new file mode 100644
index 0000000..cd34282
--- /dev/null
+++ b/drivers/bus/mhi/clients/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+obj-$(CONFIG_MHI_UCI) += uci.o
diff --git a/drivers/bus/mhi/clients/uci.c b/drivers/bus/mhi/clients/uci.c
new file mode 100644
index 0000000..a25d5d0
--- /dev/null
+++ b/drivers/bus/mhi/clients/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_idr_mutex);
+static struct class *uci_dev_class;
+static int uci_dev_major = -1;
+
+/**
+ * struct uci_chan - MHI channel for a uci device
+ * @wq: wait queue for reader/writer
+ * @lock: spin lock
+ * @pending: list of rx buffers userspace is waiting to read
+ * @cur_buf: current buffer userspace is reading
+ * @rx_size: size of the current rx buffer userspace is reading
+ */
+struct uci_chan {
+       wait_queue_head_t wq;
+
+       /* protects pending and cur_buf members */
+       spinlock_t lock;
+
+       struct list_head pending;
+       struct uci_buf *cur_buf;
+       size_t rx_size;
+};
+
+/**
+ * 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
+ * @chan: MHI channel name
+ * @lock: mutex lock
+ * @ul_chan: uplink uci channel object
+ * @dl_chan: downlink uci channel object
+ * @mtu: max tx buffer length
+ * @actual_mtu: maximum size of incoming buffer
+ * @ref_count: uci_dev reference count
+ * @open_count: device node open count
+ * @enabled: uci device probed
+ */
+struct uci_dev {
+       unsigned int minor;
+       struct mhi_device *mhi_dev;
+       const char *chan;
+
+       /* protects uci_dev struct members */
+       struct mutex lock;
+
+       struct uci_chan ul_chan;
+       struct uci_chan dl_chan;
+       size_t mtu;
+       size_t actual_mtu;
+       struct kref ref_count;
+       struct kref open_count;
+       bool enabled;
+};
+
+static int mhi_queue_inbound(struct uci_dev *udev)
+{
+       struct mhi_device *mhi_dev = udev->mhi_dev;
+       struct device *dev = &mhi_dev->dev;
+       size_t mtu = udev->mtu;
+       size_t actual_mtu = udev->actual_mtu;
+       int nr_trbs, i, ret = -EIO;
+       void *buf;
+       struct uci_buf *uci_buf;
+
+       nr_trbs = mhi_get_no_free_descriptors(mhi_dev, DMA_FROM_DEVICE);
+
+       for (i = 0; i < nr_trbs; i++) {
+               buf = kmalloc(mtu, GFP_KERNEL);
+               if (!buf)
+                       return -ENOMEM;
+
+               uci_buf = buf + actual_mtu;
+               uci_buf->data = buf;
+
+               dev_dbg(dev, "Allocated buf %d of %d size %ld\n", i, nr_trbs,
+                       actual_mtu);
+
+               ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, buf, actual_mtu,
+                                   MHI_EOT);
+               if (ret) {
+                       kfree(buf);
+                       dev_err(dev, "Failed to queue buffer %d\n", i);
+                       return ret;
+               }
+       }
+
+       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);
+
+       dev_set_drvdata(&udev->mhi_dev->dev, NULL);
+
+       kfree(udev);
+}
+
+static void mhi_uci_close(struct kref *ref)
+{
+       struct uci_dev *udev =
+               container_of(ref, struct uci_dev, open_count);
+       struct uci_buf *itr, *tmp;
+       struct uci_chan *uchan;
+
+       if (udev->enabled)
+               mhi_unprepare_from_transfer(udev->mhi_dev);
+
+       /* clean inbound channel */
+       uchan = &udev->dl_chan;
+
+       spin_lock_bh(&uchan->lock);
+       list_for_each_entry_safe(itr, tmp, &uchan->pending, node) {
+               list_del(&itr->node);
+               kfree(itr->data);
+       }
+
+       if (uchan->cur_buf)
+               kfree(uchan->cur_buf->data);
+
+       uchan->cur_buf = NULL;
+       spin_unlock_bh(&uchan->lock);
+}
+
+static int mhi_uci_release(struct inode *inode, struct file *file)
+{
+       struct uci_dev *udev = file->private_data;
+
+       kref_put(&udev->open_count, mhi_uci_close);
+       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;
+       __poll_t mask = 0;
+
+       poll_wait(file, &udev->dl_chan.wq, wait);
+       poll_wait(file, &udev->ul_chan.wq, wait);
+
+       if (!udev->enabled) {
+               mask = EPOLLERR;
+       } else {
+               uchan = &udev->dl_chan;
+               spin_lock_bh(&uchan->lock);
+               if (!list_empty(&uchan->pending) || uchan->cur_buf) {
+                       dev_dbg(dev, "Client can read from node\n");
+                       mask |= EPOLLIN | EPOLLRDNORM;
+               }
+               spin_unlock_bh(&uchan->lock);
+       }
+
+       if (!udev->enabled) {
+               mask |= EPOLLERR;
+       } else if (mhi_get_no_free_descriptors(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);
+
+       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->ul_chan;
+       size_t bytes_xfered = 0;
+       int ret, nr_avail = 0;
+
+       if (!buf || !count)
+               return -EINVAL;
+
+       /* confirm channel is active */
+       mutex_lock(&udev->lock);
+       if (!udev->enabled) {
+               ret = -ENODEV;
+               goto err_mtx_unlock;
+       }
+
+       dev_dbg(dev, "%s: to xfer: %lu bytes\n", __func__, count);
+
+       while (count) {
+               size_t xfer_size;
+               void *kbuf;
+               enum mhi_flags flags;
+
+               mutex_unlock(&udev->lock);
+               /* wait for free descriptors */
+               ret = wait_event_interruptible(uchan->wq,
+                                              (!udev->enabled) ||
+                               (nr_avail = mhi_get_no_free_descriptors(mhi_dev,
+                                              DMA_TO_DEVICE)) > 0);
+
+               mutex_lock(&udev->lock);
+               if (ret == -ERESTARTSYS) {
+                       dev_dbg(dev, "Exit signal caught for node\n");
+                       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;
+
+               if (udev->enabled)
+                       ret = mhi_queue_buf(mhi_dev, DMA_TO_DEVICE, kbuf,
+                                           xfer_size, flags);
+               else
+                       ret = -ENODEV;
+
+               if (ret) {
+                       kfree(kbuf);
+                       goto err_mtx_unlock;
+               }
+
+               bytes_xfered += xfer_size;
+               count -= xfer_size;
+               buf += xfer_size;
+       }
+
+       mutex_unlock(&udev->lock);
+       dev_dbg(dev, "%s: bytes xferred: %lu\n", __func__, bytes_xfered);
+
+       return bytes_xfered;
+
+err_mtx_unlock:
+       mutex_unlock(&udev->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->dl_chan;
+       struct device *dev = &mhi_dev->dev;
+       struct uci_buf *ubuf;
+       char *ptr;
+       size_t to_copy;
+       int ret = 0;
+
+       if (!buf)
+               return -EINVAL;
+
+       mutex_lock(&udev->lock);
+       /* confirm channel is active */
+       if (!udev->enabled) {
+               ret = -ENODEV;
+               goto err_mtx_unlock;
+       }
+
+       spin_lock_bh(&uchan->lock);
+       /* No data available to read, wait */
+       if (!uchan->cur_buf && list_empty(&uchan->pending)) {
+               dev_dbg(dev, "No data available to read waiting\n");
+
+               spin_unlock_bh(&uchan->lock);
+               mutex_unlock(&udev->lock);
+               ret = wait_event_interruptible(uchan->wq,
+                                              (!udev->enabled ||
+                                             !list_empty(&uchan->pending)));
+
+               mutex_lock(&udev->lock);
+               if (ret == -ERESTARTSYS) {
+                       dev_dbg(dev, "Exit signal caught for node\n");
+                       goto err_mtx_unlock;
+               }
+
+               if (!udev->enabled) {
+                       ret = -ENODEV;
+                       goto err_mtx_unlock;
+               }
+               spin_lock_bh(&uchan->lock);
+       }
+
+       /* new read, get the next descriptor from the list */
+       if (!uchan->cur_buf) {
+               ubuf = list_first_entry_or_null(&uchan->pending,
+                                               struct uci_buf, node);
+               if (!ubuf) {
+                       ret = -EIO;
+                       goto err_spin_unlock;
+               }
+
+               list_del(&ubuf->node);
+               uchan->cur_buf = ubuf;
+               uchan->rx_size = ubuf->len;
+               dev_dbg(dev, "Got pkt of size: %zu\n", uchan->rx_size);
+       }
+
+       ubuf = uchan->cur_buf;
+
+       /* Copy the buffer to user space */
+       to_copy = min_t(size_t, count, uchan->rx_size);
+       ptr = ubuf->data + (ubuf->len - uchan->rx_size);
+       spin_unlock_bh(&uchan->lock);
+
+       ret = copy_to_user(buf, ptr, to_copy);
+       if (ret) {
+               ret = -EFAULT;
+               goto err_mtx_unlock;
+       }
+
+       spin_lock_bh(&uchan->lock);
+
+       dev_dbg(dev, "Copied %lu of %lu bytes\n", to_copy, uchan->rx_size);
+       uchan->rx_size -= to_copy;
+
+       /* we finished with this buffer, queue it back to hardware */
+       if (!uchan->rx_size) {
+               uchan->cur_buf = NULL;
+
+               if (udev->enabled)
+                       ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE,
+                                           ubuf->data,
+                                           udev->actual_mtu, MHI_EOT);
+               else
+                       ret = -ENODEV;
+
+               if (ret) {
+                       dev_err(dev, "Failed to recycle element: %d\n", ret);
+                       kfree(ubuf->data);
+                       goto err_spin_unlock;
+               }
+       }
+       spin_unlock_bh(&uchan->lock);
+       mutex_unlock(&udev->lock);
+
+       dev_dbg(dev, "%s: Returning %lu bytes\n", __func__, to_copy);
+
+       return to_copy;
+
+err_spin_unlock:
+       spin_unlock_bh(&uchan->lock);
+err_mtx_unlock:
+       mutex_unlock(&udev->lock);
+       return ret;
+}
+
+static int mhi_uci_open(struct inode *inode, struct file *filp)
+{
+       struct uci_dev *udev = NULL;
+       unsigned int minor = iminor(inode);
+       int ret = -EIO;
+       struct uci_buf *buf_itr, *tmp;
+       struct uci_chan *dl_chan;
+       struct mhi_device *mhi_dev;
+       struct device *dev;
+
+       mutex_lock(&uci_idr_mutex);
+       udev = idr_find(&uci_idr, minor);
+       mutex_unlock(&uci_idr_mutex);
+       if (!udev) {
+               pr_err("uci dev: minor %d not found\n", minor);
+               ret = -ENODEV;
+               goto error_no_dev;
+       }
+
+       kref_get(&udev->ref_count);
+
+       mhi_dev = udev->mhi_dev;
+       dev = &mhi_dev->dev;
+
+       mutex_lock(&udev->lock);
+       if (!udev->enabled) {
+               dev_info(dev, "Node exist, but not in active state!\n");
+               goto error_open_chan;
+       }
+
+       if (!kref_get_unless_zero(&udev->open_count)) {
+               dev_dbg(dev, "Starting channel\n");
+               ret = mhi_prepare_for_transfer(udev->mhi_dev);
+               if (ret) {
+                       dev_err(dev, "Error starting transfer channels\n");
+                       goto error_open_chan;
+               }
+
+               ret = mhi_queue_inbound(udev);
+               if (ret)
+                       goto error_rx_queue;
+
+               kref_init(&udev->open_count);
+       }
+
+       dev_dbg(dev, "Node open, ref counts %u\n",
+               kref_read(&udev->open_count));
+
+       filp->private_data = udev;
+       mutex_unlock(&udev->lock);
+
+       return 0;
+
+error_rx_queue:
+       dl_chan = &udev->dl_chan;
+       mhi_unprepare_from_transfer(udev->mhi_dev);
+       list_for_each_entry_safe(buf_itr, tmp, &dl_chan->pending, node) {
+               list_del(&buf_itr->node);
+               kfree(buf_itr->data);
+       }
+error_open_chan:
+       mutex_unlock(&udev->lock);
+       kref_put(&udev->ref_count, mhi_uci_dev_release);
+error_no_dev:
+       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->ul_chan;
+       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->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->dl_chan;
+       struct device *dev = &mhi_dev->dev;
+       struct uci_buf *buf;
+
+       dev_dbg(dev, "status: %d receive_len: %zu\n",
+               mhi_result->transaction_status, mhi_result->bytes_xferd);
+
+       if (mhi_result->transaction_status == -ENOTCONN) {
+               kfree(mhi_result->buf_addr);
+               return;
+       }
+
+       spin_lock_bh(&uchan->lock);
+       buf = mhi_result->buf_addr + udev->actual_mtu;
+       buf->data = mhi_result->buf_addr;
+       buf->len = mhi_result->bytes_xferd;
+       list_add_tail(&buf->node, &uchan->pending);
+       spin_unlock_bh(&uchan->lock);
+
+       wake_up(&uchan->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, dir;
+
+       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(&udev->lock);
+
+       mutex_lock(&uci_idr_mutex);
+       index = idr_alloc(&uci_idr, udev, 0, MAX_UCI_MINORS, GFP_KERNEL);
+       mutex_unlock(&uci_idr_mutex);
+       if (index < 0) {
+               mutex_unlock(&udev->lock);
+               kfree(udev);
+               return index;
+       }
+
+       udev->minor = index;
+
+       /* 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_idr_mutex);
+               idr_remove(&uci_idr, udev->minor);
+               mutex_unlock(&uci_idr_mutex);
+               mutex_unlock(&udev->lock);
+               kfree(udev);
+               return PTR_ERR(dev);
+       }
+
+       for (dir = 0; dir < 2; dir++) {
+               struct uci_chan *uchan = (dir) ?
+                       &udev->ul_chan : &udev->dl_chan;
+               spin_lock_init(&uchan->lock);
+               init_waitqueue_head(&uchan->wq);
+               INIT_LIST_HEAD(&uchan->pending);
+       }
+
+       udev->mtu = min_t(size_t, id->driver_data, MHI_MAX_MTU);
+       udev->actual_mtu = udev->mtu - sizeof(struct uci_buf);
+       dev_set_drvdata(&mhi_dev->dev, udev);
+       udev->enabled = true;
+
+       mutex_unlock(&udev->lock);
+
+       dev_info(&mhi_dev->dev, "probed uci dev: minor %d\n", index);
+
+       return 0;
+};
+
+static void mhi_uci_remove(struct mhi_device *mhi_dev)
+{
+       struct uci_dev *udev = dev_get_drvdata(&mhi_dev->dev);
+
+       mutex_lock(&udev->lock);
+
+       /* disable the node */
+       udev->enabled = false;
+
+       wake_up(&udev->dl_chan.wq);
+       wake_up(&udev->ul_chan.wq);
+
+       /* delete the node to prevent new opens */
+       device_destroy(uci_dev_class, MKDEV(uci_dev_major, udev->minor));
+
+       mutex_lock(&uci_idr_mutex);
+       idr_remove(&uci_idr, udev->minor);
+       mutex_unlock(&uci_idr_mutex);
+
+       mutex_unlock(&udev->lock);
+
+       kref_put(&udev->ref_count, mhi_uci_dev_release);
+}
+
+/* .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 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 -ENODEV;
+       }
+
+       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);
+}
+
+module_init(mhi_uci_init);
+module_exit(mhi_uci_exit);
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MHI UCI Driver");
-- 
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