bus: mhi: devices: Add snapshot of MHI devices driver

This is a snapshot of MHI devices driver from
msm-5.15 commit 08c9da520628 ("bus: mhi: Add snapshot
of MHI devices").

Change-Id: I1f23afeedaab09f94a411f5b9eb02d2ff31a777a
Signed-off-by: Lazarus Motha <quic_lmotha@quicinc.com>

drivers/bus/mhi/devices/Kconfig

@@ -0,0 +1,47 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+menu "MHI device support"
+
+config MHI_NETDEV
+	tristate "MHI NETDEV"
+	depends on MHI_BUS
+	help
+	  MHI based net device driver for transferring IP traffic
+	  between host and modem. By enabling this driver, clients
+	  can transfer data using standard network interface. Over
+	  the air traffic goes thru mhi netdev interface.
+
+config MHI_UCI
+	tristate "MHI UCI"
+	depends on MHI_BUS && MHI_BUS_MISC
+	help
+	  MHI based uci driver is for transferring data between host and
+	  modem using standard file operations from user space. Open, read,
+	  write, ioctl, and close operations are supported by this driver.
+	  Please check mhi_uci_match_table for all supported channels that
+	  are exposed to userspace.
+
+config MHI_DTR
+	tristate "MHI DTR SIGNALING"
+	depends on MHI_BUS && MHI_BUS_MISC
+	help
+	  MHI device driver for enabling DTR<>RTS UART signaling as IP_CTRL
+	  client for userspace. Data Terminal Ready (DTR) is a control signal
+	  in RS-232 serial communications, transmitted from data terminal
+	  equipment (DTE), or host in this case, to data communications
+	  equipment (DCE), or external modem in this case to indicate that the
+	  terminal/host is ready for communications and the modem may initiate
+	  a communications channel.
+
+config MHI_SATELLITE
+	tristate "MHI SATELLITE"
+	depends on MHI_BUS
+	help
+	  MHI proxy satellite device driver enables NON-HLOS MHI satellite
+	  drivers to communicate with device over PCIe link without host
+	  involvement. Host facilitates propagation of events from device
+	  to NON-HLOS MHI satellite drivers, channel states, and power
+	  management over IPC communication. It helps in HLOS power
+	  savings.
+
+endmenu

drivers/bus/mhi/devices/Makefile

@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+mhi_dev_uci-y := mhi_uci.o
+obj-$(CONFIG_MHI_UCI) += mhi_dev_uci.o
+
+mhi_dev_netdev-y := mhi_netdev.o
+obj-$(CONFIG_MHI_NETDEV) += mhi_dev_netdev.o
+
+mhi_dev_dtr-y := mhi_dtr.o
+obj-$(CONFIG_MHI_DTR) += mhi_dev_dtr.o
+
+mhi_dev_satellite-y := mhi_satellite.o
+obj-$(CONFIG_MHI_SATELLITE) += mhi_dev_satellite.o

drivers/bus/mhi/devices/mhi_dtr.c

@@ -0,0 +1,277 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
+
+#include <linux/device.h>
+#include <linux/dma-direction.h>
+#include <linux/dma-mapping.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/mhi.h>
+#include <linux/mhi_misc.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/slab.h>
+#include <linux/termios.h>
+#include <linux/wait.h>
+
+struct dtr_ctrl_msg {
+	u32 preamble;
+	u32 msg_id;
+	u32 dest_id;
+	u32 size;
+	u32 msg;
+} __packed;
+
+static struct dtr_info {
+	struct completion completion;
+	struct mhi_device *mhi_dev;
+	void *ipc_log;
+} *dtr_info;
+
+static enum MHI_DEBUG_LEVEL dtr_log_level = MHI_MSG_LVL_INFO;
+
+#define MHI_DTR_IPC_LOG_PAGES (5)
+#define DTR_LOG(fmt, ...) do { \
+		dev_dbg(dev, "[I][%s] " fmt, __func__, ##__VA_ARGS__); \
+		if (dtr_info->ipc_log && dtr_log_level <= MHI_MSG_LVL_INFO) \
+			ipc_log_string(dtr_info->ipc_log, "[I][%s] " fmt, \
+				       __func__, ##__VA_ARGS__); \
+	} while (0)
+
+#define DTR_ERR(fmt, ...) do { \
+		dev_err(dev, "[E][%s] " fmt, __func__, ##__VA_ARGS__); \
+		if (dtr_info->ipc_log && dtr_log_level <= MHI_MSG_LVL_ERROR) \
+			ipc_log_string(dtr_info->ipc_log, "[E][%s] " fmt, \
+				       __func__, ##__VA_ARGS__); \
+	} while (0)
+
+#define CTRL_MAGIC (0x4C525443)
+#define CTRL_MSG_DTR BIT(0)
+#define CTRL_MSG_RTS BIT(1)
+#define CTRL_MSG_DCD BIT(0)
+#define CTRL_MSG_DSR BIT(1)
+#define CTRL_MSG_RI BIT(3)
+#define CTRL_HOST_STATE (0x10)
+#define CTRL_DEVICE_STATE (0x11)
+#define CTRL_GET_CHID(dtr) ((dtr)->dest_id & 0xFF)
+
+static int mhi_dtr_tiocmset(struct mhi_controller *mhi_cntrl,
+			    struct mhi_device *mhi_dev,
+			    u32 tiocm)
+{
+	struct device *dev = &mhi_dev->dev;
+	struct dtr_ctrl_msg *dtr_msg = NULL;
+	/* protects state changes for MHI device termios states */
+	spinlock_t *res_lock = &mhi_dev->dev.devres_lock;
+	u32 cur_tiocm;
+	int ret = 0;
+
+	cur_tiocm = mhi_dev->tiocm & ~(TIOCM_CD | TIOCM_DSR | TIOCM_RI);
+
+	tiocm &= (TIOCM_DTR | TIOCM_RTS);
+
+	/* state did not change */
+	if (cur_tiocm == tiocm)
+		return 0;
+
+	dtr_msg = kzalloc(sizeof(*dtr_msg), GFP_KERNEL);
+	if (!dtr_msg) {
+		ret = -ENOMEM;
+		goto tiocm_exit;
+	}
+
+	dtr_msg->preamble = CTRL_MAGIC;
+	dtr_msg->msg_id = CTRL_HOST_STATE;
+	dtr_msg->dest_id = mhi_dev->ul_chan_id;
+	dtr_msg->size = sizeof(u32);
+	if (tiocm & TIOCM_DTR)
+		dtr_msg->msg |= CTRL_MSG_DTR;
+	if (tiocm & TIOCM_RTS)
+		dtr_msg->msg |= CTRL_MSG_RTS;
+
+	reinit_completion(&dtr_info->completion);
+	ret = mhi_queue_buf(dtr_info->mhi_dev, DMA_TO_DEVICE, dtr_msg,
+			    sizeof(*dtr_msg), MHI_EOT);
+	if (ret)
+		goto tiocm_exit;
+
+	ret = wait_for_completion_timeout(&dtr_info->completion,
+				msecs_to_jiffies(mhi_cntrl->timeout_ms));
+	if (!ret) {
+		DTR_ERR("Failed to receive transfer callback\n");
+		ret = -EIO;
+		goto tiocm_exit;
+	}
+
+	DTR_LOG("DTR TIOCMSET update done for %s\n", mhi_dev->name);
+	ret = 0;
+	spin_lock_irq(res_lock);
+	mhi_dev->tiocm &= ~(TIOCM_DTR | TIOCM_RTS);
+	mhi_dev->tiocm |= tiocm;
+	spin_unlock_irq(res_lock);
+
+tiocm_exit:
+	kfree(dtr_msg);
+
+	return ret;
+}
+
+long mhi_device_ioctl(struct mhi_device *mhi_dev, unsigned int cmd,
+		      unsigned long arg)
+{
+	struct device *dev = &mhi_dev->dev;
+	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
+	int ret;
+
+	/* ioctl not supported by this controller */
+	if (!dtr_info->mhi_dev) {
+		DTR_ERR("%s request denied. DTR channels not running\n",
+			mhi_dev->name);
+		return -EIO;
+	}
+
+	switch (cmd) {
+	case TIOCMGET:
+		return mhi_dev->tiocm;
+	case TIOCMSET:
+	{
+		u32 tiocm;
+
+		ret = get_user(tiocm, (u32 __user *)arg);
+		if (ret)
+			return ret;
+
+		return mhi_dtr_tiocmset(mhi_cntrl, mhi_dev, tiocm);
+	}
+	default:
+		break;
+	}
+
+	return -ENOIOCTLCMD;
+}
+EXPORT_SYMBOL(mhi_device_ioctl);
+
+static void mhi_dtr_dl_xfer_cb(struct mhi_device *mhi_dev,
+			       struct mhi_result *mhi_result)
+{
+	struct device *dev = &mhi_dev->dev;
+	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
+	struct dtr_ctrl_msg *dtr_msg = mhi_result->buf_addr;
+	/* protects state changes for MHI device termios states */
+	spinlock_t *res_lock;
+
+	if (mhi_result->bytes_xferd != sizeof(*dtr_msg)) {
+		DTR_ERR("Unexpected length %zu received\n",
+			mhi_result->bytes_xferd);
+		return;
+	}
+
+	DTR_LOG("preamble: 0x%x msg_id: %u dest_id: %u msg: 0x%x\n",
+		dtr_msg->preamble, dtr_msg->msg_id, dtr_msg->dest_id,
+		dtr_msg->msg);
+
+	mhi_dev = mhi_get_device_for_channel(mhi_cntrl, CTRL_GET_CHID(dtr_msg));
+	if (!mhi_dev)
+		return;
+
+	res_lock = &mhi_dev->dev.devres_lock;
+	spin_lock_irq(res_lock);
+	mhi_dev->tiocm &= ~(TIOCM_CD | TIOCM_DSR | TIOCM_RI);
+
+	if (dtr_msg->msg & CTRL_MSG_DCD)
+		mhi_dev->tiocm |= TIOCM_CD;
+
+	if (dtr_msg->msg & CTRL_MSG_DSR)
+		mhi_dev->tiocm |= TIOCM_DSR;
+
+	if (dtr_msg->msg & CTRL_MSG_RI)
+		mhi_dev->tiocm |= TIOCM_RI;
+	spin_unlock_irq(res_lock);
+
+	/* Notify the update */
+	mhi_notify(mhi_dev, MHI_CB_DTR_SIGNAL);
+}
+
+static void mhi_dtr_ul_xfer_cb(struct mhi_device *mhi_dev,
+			       struct mhi_result *mhi_result)
+{
+	struct device *dev = &mhi_dev->dev;
+
+	DTR_LOG("Received with status: %d\n", mhi_result->transaction_status);
+	if (!mhi_result->transaction_status)
+		complete(&dtr_info->completion);
+}
+
+static void mhi_dtr_status_cb(struct mhi_device *mhi_dev, enum mhi_callback cb)
+{
+	struct device *dev = &mhi_dev->dev;
+	int ret;
+
+	if (cb != MHI_CB_DTR_START_CHANNELS)
+		return;
+
+	ret = mhi_prepare_for_transfer(mhi_dev, 0);
+	if (!ret)
+		dtr_info->mhi_dev = mhi_dev;
+
+	DTR_LOG("DTR channels start attempt returns: %d\n", ret);
+}
+
+static void mhi_dtr_remove(struct mhi_device *mhi_dev)
+{
+	dtr_info->mhi_dev = NULL;
+}
+
+static int mhi_dtr_probe(struct mhi_device *mhi_dev,
+			 const struct mhi_device_id *id)
+{
+	struct device *dev = &mhi_dev->dev;
+
+	dtr_info->ipc_log = ipc_log_context_create(MHI_DTR_IPC_LOG_PAGES,
+						   dev_name(&mhi_dev->dev), 0);
+
+	DTR_LOG("Probe complete\n");
+
+	return 0;
+}
+
+static const struct mhi_device_id mhi_dtr_table[] = {
+	{ .chan = "IP_CTRL" },
+	{},
+};
+
+static struct mhi_driver mhi_dtr_driver = {
+	.id_table = mhi_dtr_table,
+	.remove = mhi_dtr_remove,
+	.probe = mhi_dtr_probe,
+	.ul_xfer_cb = mhi_dtr_ul_xfer_cb,
+	.dl_xfer_cb = mhi_dtr_dl_xfer_cb,
+	.status_cb = mhi_dtr_status_cb,
+	.driver = {
+		.name = "MHI_DTR",
+		.owner = THIS_MODULE,
+	}
+};
+
+static int __init mhi_dtr_init(void)
+{
+	dtr_info = kzalloc(sizeof(*dtr_info), GFP_KERNEL);
+	if (!dtr_info)
+		return -ENOMEM;
+
+	init_completion(&dtr_info->completion);
+
+	return mhi_driver_register(&mhi_dtr_driver);
+}
+module_init(mhi_dtr_init);
+
+static void __exit mhi_dtr_exit(void)
+{
+	mhi_driver_unregister(&mhi_dtr_driver);
+	kfree(dtr_info);
+}
+module_exit(mhi_dtr_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("MHI_DTR");
+MODULE_DESCRIPTION("MHI DTR Driver");

drivers/bus/mhi/devices/mhi_uci.c

@@ -0,0 +1,825 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/dma-direction.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/ipc_logging.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/termios.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+#include <linux/uaccess.h>
+#include <linux/mhi.h>
+#include <linux/mhi_misc.h>
+
+#define MHI_UCI_DRIVER_NAME "mhi_uci"
+
+struct uci_chan {
+	wait_queue_head_t wq;
+	spinlock_t lock;
+	struct list_head pending; /* user space waiting to read */
+	struct uci_buf *cur_buf; /* current buffer user space reading */
+	size_t rx_size;
+	struct mutex chan_lock;
+};
+
+struct uci_buf {
+	void *data;
+	size_t len;
+	struct list_head node;
+};
+
+struct uci_dev {
+	struct list_head node;
+	dev_t devt;
+	struct device *dev;
+	struct mhi_device *mhi_dev;
+	const char *chan;
+	struct mutex mutex; /* sync open and close */
+	struct uci_chan ul_chan;
+	struct uci_chan dl_chan;
+	size_t mtu;
+	size_t actual_mtu; /* maximum size of incoming buffer */
+	int ref_count;
+	bool enabled;
+	u32 tiocm;
+	void *ipc_log;
+	enum MHI_DEBUG_LEVEL msg_lvl;
+};
+
+struct mhi_uci_drv {
+	struct list_head head;
+	struct mutex lock;
+	struct class *class;
+	int major;
+	dev_t dev_t;
+};
+
+#ifdef CONFIG_MHI_BUS_DEBUG
+#define MHI_UCI_LOG_LVL MHI_MSG_LVL_VERBOSE
+#else
+#define MHI_UCI_LOG_LVL MHI_MSG_LVL_ERROR
+#endif
+
+#define MHI_UCI_IPC_LOG_PAGES (50)
+#define MSG_VERB(fmt, ...) do { \
+		if (uci_dev->ipc_log && uci_dev->msg_lvl <= MHI_MSG_LVL_VERBOSE) \
+			ipc_log_string(uci_dev->ipc_log, "%s[D][%s] " fmt, \
+				       "", __func__, ##__VA_ARGS__); \
+	} while (0)
+
+#define MSG_LOG(fmt, ...) do { \
+		if (uci_dev->ipc_log && uci_dev->msg_lvl <= MHI_MSG_LVL_INFO) \
+			ipc_log_string(uci_dev->ipc_log, "%s[I][%s] " fmt, \
+				       "", __func__, ##__VA_ARGS__); \
+	} while (0)
+
+#define MSG_ERR(fmt, ...) do { \
+		pr_err("[E][%s] " fmt, __func__, ##__VA_ARGS__); \
+		if (uci_dev->ipc_log && uci_dev->msg_lvl <= MHI_MSG_LVL_ERROR) \
+			ipc_log_string(uci_dev->ipc_log, "%s[E][%s] " fmt, \
+				       "", __func__, ##__VA_ARGS__); \
+	} while (0)
+
+#define MAX_UCI_DEVICES (64)
+
+const char * const mhi_uci_log_level_str[MHI_MSG_LVL_MAX] = {
+	[MHI_MSG_LVL_VERBOSE] = "Verbose",
+	[MHI_MSG_LVL_INFO] = "Info",
+	[MHI_MSG_LVL_ERROR] = "Error",
+	[MHI_MSG_LVL_CRITICAL] = "Critical",
+	[MHI_MSG_LVL_MASK_ALL] = "Mask all",
+};
+#define MHI_UCI_LOG_LEVEL_STR(level) ((level >= MHI_MSG_LVL_MAX || \
+				      !mhi_uci_log_level_str[level]) ? \
+				      "Mask all" : mhi_uci_log_level_str[level])
+
+static DECLARE_BITMAP(uci_minors, MAX_UCI_DEVICES);
+static struct mhi_uci_drv mhi_uci_drv;
+
+static int mhi_queue_inbound(struct uci_dev *uci_dev)
+{
+	struct mhi_device *mhi_dev = uci_dev->mhi_dev;
+	int nr_trbs = mhi_get_free_desc_count(mhi_dev, DMA_FROM_DEVICE);
+	size_t mtu = uci_dev->mtu;
+	size_t actual_mtu = uci_dev->actual_mtu;
+	void *buf;
+	struct uci_buf *uci_buf;
+	int ret = -EIO, i;
+
+	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;
+
+		MSG_VERB("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);
+			MSG_ERR("Failed to queue buffer %d\n", i);
+			return ret;
+		}
+	}
+
+	return ret;
+}
+
+static long mhi_uci_ioctl(struct file *file,
+			  unsigned int cmd,
+			  unsigned long arg)
+{
+	struct uci_dev *uci_dev = file->private_data;
+	struct mhi_device *mhi_dev = uci_dev->mhi_dev;
+	struct uci_chan *uci_chan = &uci_dev->dl_chan;
+	long ret = -ENOIOCTLCMD;
+
+	mutex_lock(&uci_dev->mutex);
+
+	if (cmd == TIOCMGET) {
+		spin_lock_bh(&uci_chan->lock);
+		ret = uci_dev->tiocm;
+		spin_unlock_bh(&uci_chan->lock);
+	} else if (uci_dev->enabled) {
+		ret = mhi_device_ioctl(mhi_dev, cmd, arg);
+		if (!ret) {
+			spin_lock_bh(&uci_chan->lock);
+			uci_dev->tiocm = mhi_dev->tiocm;
+			spin_unlock_bh(&uci_chan->lock);
+		}
+	}
+
+	mutex_unlock(&uci_dev->mutex);
+
+	return ret;
+}
+
+static int mhi_uci_release(struct inode *inode, struct file *file)
+{
+	struct uci_dev *uci_dev = file->private_data;
+
+	mutex_lock(&uci_dev->mutex);
+	uci_dev->ref_count--;
+	if (!uci_dev->ref_count) {
+		struct uci_buf *itr, *tmp;
+		struct uci_chan *uci_chan;
+
+		MSG_LOG("Last client left, closing node\n");
+
+		if (uci_dev->enabled)
+			mhi_unprepare_from_transfer(uci_dev->mhi_dev);
+
+		/* clean inbound channel */
+		uci_chan = &uci_dev->dl_chan;
+		list_for_each_entry_safe(itr, tmp, &uci_chan->pending, node) {
+			list_del(&itr->node);
+			kfree(itr->data);
+		}
+		if (uci_chan->cur_buf)
+			kfree(uci_chan->cur_buf->data);
+
+		uci_chan->cur_buf = NULL;
+
+		if (!uci_dev->enabled) {
+			MSG_LOG("Node is deleted, freeing dev node\n");
+			mutex_unlock(&uci_dev->mutex);
+			mutex_destroy(&uci_dev->mutex);
+			mutex_destroy(&uci_dev->dl_chan.chan_lock);
+			mutex_destroy(&uci_dev->ul_chan.chan_lock);
+			clear_bit(MINOR(uci_dev->devt), uci_minors);
+			kfree(uci_dev);
+			return 0;
+		}
+	}
+
+	MSG_LOG("exit: ref_count:%d\n", uci_dev->ref_count);
+
+	mutex_unlock(&uci_dev->mutex);
+
+	return 0;
+}
+
+static __poll_t mhi_uci_poll(struct file *file, poll_table *wait)
+{
+	struct uci_dev *uci_dev = file->private_data;
+	struct mhi_device *mhi_dev = uci_dev->mhi_dev;
+	struct uci_chan *uci_chan;
+	__poll_t mask = 0;
+
+	poll_wait(file, &uci_dev->dl_chan.wq, wait);
+	poll_wait(file, &uci_dev->ul_chan.wq, wait);
+
+	uci_chan = &uci_dev->dl_chan;
+	spin_lock_bh(&uci_chan->lock);
+	if (!uci_dev->enabled) {
+		mask = EPOLLERR;
+	} else {
+		if (!list_empty(&uci_chan->pending) || uci_chan->cur_buf) {
+			MSG_VERB("Client can read from node\n");
+			mask |= EPOLLIN | EPOLLRDNORM;
+		}
+
+		if (uci_dev->tiocm) {
+			MSG_VERB("Line status changed\n");
+			mask |= EPOLLPRI;
+		}
+	}
+	spin_unlock_bh(&uci_chan->lock);
+
+	uci_chan = &uci_dev->ul_chan;
+	spin_lock_bh(&uci_chan->lock);
+	if (!uci_dev->enabled) {
+		mask |= EPOLLERR;
+	} else if (mhi_get_free_desc_count(mhi_dev, DMA_TO_DEVICE) > 0) {
+		MSG_VERB("Client can write to node\n");
+		mask |= EPOLLOUT | EPOLLWRNORM;
+	}
+	spin_unlock_bh(&uci_chan->lock);
+
+	MSG_LOG("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 *uci_dev = file->private_data;
+	struct mhi_device *mhi_dev = uci_dev->mhi_dev;
+	struct uci_chan *uci_chan = &uci_dev->ul_chan;
+	size_t bytes_xfered = 0;
+	int ret, nr_avail;
+
+	if (!buf || !count)
+		return -EINVAL;
+
+	mutex_lock(&uci_chan->chan_lock);
+
+	/* confirm channel is active */
+	spin_lock_bh(&uci_chan->lock);
+	if (!uci_dev->enabled) {
+		spin_unlock_bh(&uci_chan->lock);
+		ret = -ERESTARTSYS;
+		goto err_mtx_unlock;
+	}
+
+	MSG_VERB("Enter: to xfer:%lu bytes\n", count);
+
+	while (count) {
+		size_t xfer_size;
+		void *kbuf;
+		enum mhi_flags flags;
+
+		spin_unlock_bh(&uci_chan->lock);
+
+		/* wait for free descriptors */
+		ret = wait_event_interruptible(uci_chan->wq,
+			(!uci_dev->enabled) ||
+			(nr_avail = mhi_get_free_desc_count(mhi_dev,
+							DMA_TO_DEVICE)) > 0);
+
+		if (ret == -ERESTARTSYS || !uci_dev->enabled) {
+			MSG_LOG("Exit signal caught for node or not enabled\n");
+			ret = -ERESTARTSYS;
+			goto err_mtx_unlock;
+		}
+
+		xfer_size = min_t(size_t, count, uci_dev->mtu);
+		kbuf = kmalloc(xfer_size, GFP_KERNEL);
+		if (!kbuf) {
+			MSG_ERR("Failed to allocate memory %lu\n", xfer_size);
+			ret = -ENOMEM;
+			goto err_mtx_unlock;
+		}
+
+		ret = copy_from_user(kbuf, buf, xfer_size);
+		if (unlikely(ret)) {
+			kfree(kbuf);
+			goto err_mtx_unlock;
+		}
+
+		spin_lock_bh(&uci_chan->lock);
+
+		/* if ring is full after this force EOT */
+		if (nr_avail > 1 && (count - xfer_size))
+			flags = MHI_CHAIN;
+		else
+			flags = MHI_EOT;
+
+		if (uci_dev->enabled)
+			ret = mhi_queue_buf(mhi_dev, DMA_TO_DEVICE, kbuf,
+					    xfer_size, flags);
+		else
+			ret = -ERESTARTSYS;
+
+		if (ret) {
+			kfree(kbuf);
+			goto sys_interrupt;
+		}
+
+		bytes_xfered += xfer_size;
+		count -= xfer_size;
+		buf += xfer_size;
+	}
+
+	spin_unlock_bh(&uci_chan->lock);
+	mutex_unlock(&uci_chan->chan_lock);
+	MSG_VERB("Exit: Number of bytes xferred:%lu\n", bytes_xfered);
+
+	return bytes_xfered;
+
+sys_interrupt:
+	spin_unlock_bh(&uci_chan->lock);
+err_mtx_unlock:
+	mutex_unlock(&uci_chan->chan_lock);
+
+	return ret;
+}
+
+static ssize_t mhi_uci_read(struct file *file,
+			    char __user *buf,
+			    size_t count,
+			    loff_t *ppos)
+{
+	struct uci_dev *uci_dev = file->private_data;
+	struct mhi_device *mhi_dev = uci_dev->mhi_dev;
+	struct uci_chan *uci_chan = &uci_dev->dl_chan;
+	struct uci_buf *uci_buf;
+	char *ptr;
+	size_t to_copy;
+	int ret = 0;
+
+	if (!buf)
+		return -EINVAL;
+
+	MSG_VERB("Client provided buf len:%lu\n", count);
+
+	mutex_lock(&uci_chan->chan_lock);
+
+	/* confirm channel is active */
+	spin_lock_bh(&uci_chan->lock);
+	if (!uci_dev->enabled) {
+		spin_unlock_bh(&uci_chan->lock);
+		ret = -ERESTARTSYS;
+		goto err_mtx_unlock;
+	}
+
+	/* No data available to read, wait */
+	if (!uci_chan->cur_buf && list_empty(&uci_chan->pending)) {
+		MSG_VERB("No data available to read waiting\n");
+
+		spin_unlock_bh(&uci_chan->lock);
+		ret = wait_event_interruptible(uci_chan->wq,
+				(!uci_dev->enabled ||
+				 !list_empty(&uci_chan->pending)));
+		if (ret == -ERESTARTSYS) {
+			MSG_LOG("Exit signal caught for node\n");
+			ret = -ERESTARTSYS;
+			goto err_mtx_unlock;
+		}
+
+		spin_lock_bh(&uci_chan->lock);
+		if (!uci_dev->enabled) {
+			MSG_LOG("node is disabled\n");
+			ret = -ERESTARTSYS;
+			goto read_error;
+		}
+	}
+
+	/* new read, get the next descriptor from the list */
+	if (!uci_chan->cur_buf) {
+		uci_buf = list_first_entry_or_null(&uci_chan->pending,
+						   struct uci_buf, node);
+		if (unlikely(!uci_buf)) {
+			ret = -EIO;
+			goto read_error;
+		}
+
+		list_del(&uci_buf->node);
+		uci_chan->cur_buf = uci_buf;
+		uci_chan->rx_size = uci_buf->len;
+		MSG_VERB("Got pkt of size:%zu\n", uci_chan->rx_size);
+	}
+
+	uci_buf = uci_chan->cur_buf;
+	spin_unlock_bh(&uci_chan->lock);
+
+	/* Copy the buffer to user space */
+	to_copy = min_t(size_t, count, uci_chan->rx_size);
+	ptr = uci_buf->data + (uci_buf->len - uci_chan->rx_size);
+	ret = copy_to_user(buf, ptr, to_copy);
+	if (ret)
+		goto err_mtx_unlock;
+
+	MSG_VERB("Copied %lu of %lu bytes\n", to_copy, uci_chan->rx_size);
+	uci_chan->rx_size -= to_copy;
+
+	/* we finished with this buffer, queue it back to hardware */
+	if (!uci_chan->rx_size) {
+		spin_lock_bh(&uci_chan->lock);
+		uci_chan->cur_buf = NULL;
+
+		if (uci_dev->enabled)
+			ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE,
+					    uci_buf->data,
+					    uci_dev->actual_mtu, MHI_EOT);
+		else
+			ret = -ERESTARTSYS;
+
+		if (ret) {
+			MSG_ERR("Failed to recycle element\n");
+			kfree(uci_buf->data);
+			goto read_error;
+		}
+
+		spin_unlock_bh(&uci_chan->lock);
+	}
+
+	MSG_VERB("Returning %lu bytes\n", to_copy);
+	mutex_unlock(&uci_chan->chan_lock);
+
+	return to_copy;
+
+read_error:
+	spin_unlock_bh(&uci_chan->lock);
+err_mtx_unlock:
+	mutex_unlock(&uci_chan->chan_lock);
+	return ret;
+}
+
+static int mhi_uci_open(struct inode *inode, struct file *filp)
+{
+	struct uci_dev *uci_dev = NULL, *tmp_dev;
+	int ret = -EIO;
+	struct uci_buf *buf_itr, *tmp;
+	struct uci_chan *dl_chan;
+
+	mutex_lock(&mhi_uci_drv.lock);
+	list_for_each_entry(tmp_dev, &mhi_uci_drv.head, node) {
+		if (tmp_dev->devt == inode->i_rdev) {
+			uci_dev = tmp_dev;
+			break;
+		}
+	}
+
+	/* could not find a minor node */
+	if (!uci_dev)
+		goto error_exit;
+
+	mutex_lock(&uci_dev->mutex);
+	if (!uci_dev->enabled) {
+		MSG_ERR("Node exist, but not in active state!\n");
+		goto error_open_chan;
+	}
+
+	uci_dev->ref_count++;
+
+	MSG_LOG("Node open, ref counts %u\n", uci_dev->ref_count);
+
+	if (uci_dev->ref_count == 1) {
+		MSG_LOG("Starting channel\n");
+		ret = mhi_prepare_for_transfer(uci_dev->mhi_dev, 0);
+		if (ret) {
+			MSG_ERR("Error starting transfer channels\n");
+			uci_dev->ref_count--;
+			goto error_open_chan;
+		}
+
+		ret = mhi_queue_inbound(uci_dev);
+		if (ret)
+			goto error_rx_queue;
+	}
+
+	filp->private_data = uci_dev;
+	mutex_unlock(&uci_dev->mutex);
+	mutex_unlock(&mhi_uci_drv.lock);
+
+	return 0;
+
+ error_rx_queue:
+	dl_chan = &uci_dev->dl_chan;
+	mhi_unprepare_from_transfer(uci_dev->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(&uci_dev->mutex);
+
+error_exit:
+	mutex_unlock(&mhi_uci_drv.lock);
+
+	return ret;
+}
+
+static const struct file_operations mhidev_fops = {
+	.open = mhi_uci_open,
+	.release = mhi_uci_release,
+	.read = mhi_uci_read,
+	.write = mhi_uci_write,
+	.poll = mhi_uci_poll,
+	.unlocked_ioctl = mhi_uci_ioctl,
+};
+
+static ssize_t log_level_show(struct device *dev,
+			      struct device_attribute *attr,
+			      char *buf)
+{
+	struct mhi_device *mhi_dev = to_mhi_device(dev);
+	struct uci_dev *uci_dev = dev_get_drvdata(&mhi_dev->dev);
+
+	if (!uci_dev)
+		return -EIO;
+
+	return scnprintf(buf, PAGE_SIZE,
+			 "IPC log level begins from: %s\n",
+			 MHI_UCI_LOG_LEVEL_STR(uci_dev->msg_lvl));
+}
+
+static ssize_t log_level_store(struct device *dev,
+			       struct device_attribute *attr,
+			       const char *buf,
+			       size_t count)
+{
+	struct mhi_device *mhi_dev = to_mhi_device(dev);
+	struct uci_dev *uci_dev = dev_get_drvdata(&mhi_dev->dev);
+	enum MHI_DEBUG_LEVEL log_level;
+
+	if (kstrtou32(buf, 0, &log_level) < 0)
+		return -EINVAL;
+
+	if (!uci_dev)
+		return -EIO;
+
+	uci_dev->msg_lvl = log_level;
+
+	MSG_LOG("IPC log level changed to: %s\n",
+		MHI_UCI_LOG_LEVEL_STR(log_level));
+
+	return count;
+}
+static DEVICE_ATTR_RW(log_level);
+
+static struct attribute *mhi_uci_attrs[] = {
+	&dev_attr_log_level.attr,
+	NULL,
+};
+
+static const struct attribute_group mhi_uci_group = {
+	.attrs = mhi_uci_attrs,
+};
+
+static void mhi_uci_remove(struct mhi_device *mhi_dev)
+{
+	struct uci_dev *uci_dev = dev_get_drvdata(&mhi_dev->dev);
+
+	MSG_LOG("Enter\n");
+
+
+	mutex_lock(&mhi_uci_drv.lock);
+	mutex_lock(&uci_dev->mutex);
+
+	/* disable the node */
+	spin_lock_irq(&uci_dev->dl_chan.lock);
+	spin_lock_irq(&uci_dev->ul_chan.lock);
+	uci_dev->enabled = false;
+	spin_unlock_irq(&uci_dev->ul_chan.lock);
+	spin_unlock_irq(&uci_dev->dl_chan.lock);
+	wake_up(&uci_dev->dl_chan.wq);
+	wake_up(&uci_dev->ul_chan.wq);
+
+	/* delete the node to prevent new opens */
+	device_destroy(mhi_uci_drv.class, uci_dev->devt);
+	uci_dev->dev = NULL;
+	list_del(&uci_dev->node);
+	sysfs_remove_group(&mhi_dev->dev.kobj, &mhi_uci_group);
+
+	/* safe to free memory only if all file nodes are closed */
+	if (!uci_dev->ref_count) {
+		mutex_unlock(&uci_dev->mutex);
+		mutex_destroy(&uci_dev->mutex);
+		mutex_destroy(&uci_dev->dl_chan.chan_lock);
+		mutex_destroy(&uci_dev->ul_chan.chan_lock);
+		clear_bit(MINOR(uci_dev->devt), uci_minors);
+		kfree(uci_dev);
+		mutex_unlock(&mhi_uci_drv.lock);
+		return;
+	}
+
+	MSG_LOG("Exit\n");
+	mutex_unlock(&uci_dev->mutex);
+	mutex_unlock(&mhi_uci_drv.lock);
+
+}
+
+static int mhi_uci_probe(struct mhi_device *mhi_dev,
+			 const struct mhi_device_id *id)
+{
+	struct uci_dev *uci_dev;
+	char node_name[32];
+	int minor, dir, ret;
+
+	uci_dev = kzalloc(sizeof(*uci_dev), GFP_KERNEL);
+	if (!uci_dev)
+		return -ENOMEM;
+
+	mutex_init(&uci_dev->mutex);
+	uci_dev->mhi_dev = mhi_dev;
+
+	minor = find_first_zero_bit(uci_minors, MAX_UCI_DEVICES);
+	if (minor >= MAX_UCI_DEVICES) {
+		kfree(uci_dev);
+		return -ENOSPC;
+	}
+
+	snprintf(node_name, sizeof(node_name), "%s_pipe_%d",
+		 dev_name(mhi_dev->dev.parent), mhi_dev->ul_chan_id);
+
+	mutex_lock(&uci_dev->mutex);
+	mutex_lock(&mhi_uci_drv.lock);
+
+	uci_dev->devt = MKDEV(mhi_uci_drv.major, minor);
+	uci_dev->dev = device_create(mhi_uci_drv.class, &mhi_dev->dev,
+				     uci_dev->devt, uci_dev, "%s", node_name);
+	if (IS_ERR(uci_dev->dev)) {
+		mutex_unlock(&mhi_uci_drv.lock);
+		mutex_unlock(&uci_dev->mutex);
+		mutex_destroy(&uci_dev->mutex);
+		ret = PTR_ERR(uci_dev->dev);
+		kfree(uci_dev);
+		return ret;
+	}
+
+	set_bit(minor, uci_minors);
+
+	/* create debugging buffer */
+	uci_dev->ipc_log = ipc_log_context_create(MHI_UCI_IPC_LOG_PAGES,
+						  dev_name(&mhi_dev->dev), 0);
+	uci_dev->msg_lvl = MHI_UCI_LOG_LVL;
+	ret = sysfs_create_group(&mhi_dev->dev.kobj, &mhi_uci_group);
+	if (ret)
+		MSG_ERR("Failed to create MHI UCI sysfs group\n");
+
+	for (dir = 0; dir < 2; dir++) {
+		struct uci_chan *uci_chan = (dir) ?
+			&uci_dev->ul_chan : &uci_dev->dl_chan;
+		spin_lock_init(&uci_chan->lock);
+		mutex_init(&uci_chan->chan_lock);
+		init_waitqueue_head(&uci_chan->wq);
+		INIT_LIST_HEAD(&uci_chan->pending);
+	}
+
+	uci_dev->mtu = min_t(size_t, id->driver_data, MHI_MAX_MTU);
+	uci_dev->actual_mtu = uci_dev->mtu -  sizeof(struct uci_buf);
+	dev_set_drvdata(&mhi_dev->dev, uci_dev);
+	uci_dev->enabled = true;
+
+	list_add(&uci_dev->node, &mhi_uci_drv.head);
+	mutex_unlock(&mhi_uci_drv.lock);
+	mutex_unlock(&uci_dev->mutex);
+
+	MSG_LOG("channel:%s successfully probed\n", mhi_dev->name);
+
+	return 0;
+};
+
+static void mhi_ul_xfer_cb(struct mhi_device *mhi_dev,
+			   struct mhi_result *mhi_result)
+{
+	struct uci_dev *uci_dev = dev_get_drvdata(&mhi_dev->dev);
+	struct uci_chan *uci_chan = &uci_dev->ul_chan;
+
+	MSG_VERB("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(&uci_chan->wq);
+}
+
+static void mhi_dl_xfer_cb(struct mhi_device *mhi_dev,
+			   struct mhi_result *mhi_result)
+{
+	struct uci_dev *uci_dev = dev_get_drvdata(&mhi_dev->dev);
+	struct uci_chan *uci_chan = &uci_dev->dl_chan;
+	unsigned long flags;
+	struct uci_buf *buf;
+
+	MSG_VERB("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_irqsave(&uci_chan->lock, flags);
+	buf = mhi_result->buf_addr + uci_dev->actual_mtu;
+	buf->data = mhi_result->buf_addr;
+	buf->len = mhi_result->bytes_xferd;
+	list_add_tail(&buf->node, &uci_chan->pending);
+	spin_unlock_irqrestore(&uci_chan->lock, flags);
+
+	if (mhi_dev->dev.power.wakeup)
+		pm_wakeup_hard_event(&mhi_dev->dev);
+
+	wake_up(&uci_chan->wq);
+}
+
+static void mhi_status_cb(struct mhi_device *mhi_dev, enum mhi_callback reason)
+{
+	struct uci_dev *uci_dev = dev_get_drvdata(&mhi_dev->dev);
+	struct uci_chan *uci_chan = &uci_dev->dl_chan;
+	unsigned long flags;
+
+	if (reason == MHI_CB_DTR_SIGNAL) {
+		spin_lock_irqsave(&uci_chan->lock, flags);
+		uci_dev->tiocm = mhi_dev->tiocm;
+		spin_unlock_irqrestore(&uci_chan->lock, flags);
+		wake_up(&uci_chan->wq);
+	}
+}
+
+/* .driver_data stores max mtu */
+static const struct mhi_device_id mhi_uci_match_table[] = {
+	{ .chan = "LOOPBACK", .driver_data = 0x1000 },
+	{ .chan = "SAHARA", .driver_data = 0x8000 },
+	{ .chan = "DIAG", .driver_data = 0x1000 },
+	{ .chan = "EFS", .driver_data = 0x1000 },
+	{ .chan = "QMI0", .driver_data = 0x1000 },
+	{ .chan = "QMI1", .driver_data = 0x1000 },
+	{ .chan = "TF", .driver_data = 0x1000 },
+	{ .chan = "DCI", .driver_data = 0x1000 },
+	{ .chan = "DUN", .driver_data = 0x1000 },
+	{},
+};
+
+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,
+	.status_cb = mhi_status_cb,
+	.driver = {
+		.name = MHI_UCI_DRIVER_NAME,
+		.owner = THIS_MODULE,
+	},
+};
+
+static int mhi_uci_init(void)
+{
+	int ret;
+
+	ret = register_chrdev(0, MHI_UCI_DRIVER_NAME, &mhidev_fops);
+	if (ret < 0)
+		return ret;
+
+	mhi_uci_drv.major = ret;
+	mhi_uci_drv.class = class_create(THIS_MODULE, MHI_UCI_DRIVER_NAME);
+	if (IS_ERR(mhi_uci_drv.class))
+		return -ENODEV;
+
+	mutex_init(&mhi_uci_drv.lock);
+	INIT_LIST_HEAD(&mhi_uci_drv.head);
+
+	ret = mhi_driver_register(&mhi_uci_driver);
+	if (ret)
+		class_destroy(mhi_uci_drv.class);
+
+	return ret;
+}
+module_init(mhi_uci_init);
+
+static void __exit mhi_uci_exit(void)
+{
+	if (mhi_uci_drv.major) {
+		unregister_chrdev_region(MKDEV(mhi_uci_drv.major, 0),
+				mhi_uci_drv.major);
+		mhi_uci_drv.major = 0;
+	}
+
+	class_destroy(mhi_uci_drv.class);
+
+	mhi_driver_unregister(&mhi_uci_driver);
+}
+module_exit(mhi_uci_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("MHI_UCI");
+MODULE_DESCRIPTION("MHI UCI Driver");