Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

4 files changed, 1265 insertions, 0 deletions

diff --git a/drivers/tty/serdev/Kconfig b/drivers/tty/serdev/Kconfig
new file mode 100644
index 000000000..e6dfe949a
--- /dev/null
+++ b/drivers/tty/serdev/Kconfig
@@ -0,0 +1,32 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Serial bus device driver configuration
+#
+menuconfig SERIAL_DEV_BUS
+	tristate "Serial device bus"
+	help
+	  Core support for devices connected via a serial port.
+
+	  Note that you typically also want to enable TTY port controller support.
+
+config RUST_SERIAL_DEV_BUS_ABSTRACTIONS
+	bool "Rust Serial device bus abstractions"
+	depends on RUST
+	select SERIAL_DEV_BUS
+	help
+	  This enables the Rust abstraction for the serial device bus API.
+
+if SERIAL_DEV_BUS
+
+config SERIAL_DEV_CTRL_TTYPORT
+	bool "Serial device TTY port controller"
+	help
+	  Say Y here if you want to use the Serial device bus with common TTY
+	  drivers (e.g. serial drivers).
+
+	  If unsure, say Y.
+	depends on TTY
+	depends on SERIAL_DEV_BUS != m
+	default y
+
+endif
diff --git a/drivers/tty/serdev/Makefile b/drivers/tty/serdev/Makefile
new file mode 100644
index 000000000..078417e5b
--- /dev/null
+++ b/drivers/tty/serdev/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+serdev-objs := core.o
+
+obj-$(CONFIG_SERIAL_DEV_BUS) += serdev.o
+
+obj-$(CONFIG_SERIAL_DEV_CTRL_TTYPORT) += serdev-ttyport.o
diff --git a/drivers/tty/serdev/core.c b/drivers/tty/serdev/core.c
new file mode 100644
index 000000000..7500efcdf
--- /dev/null
+++ b/drivers/tty/serdev/core.c
@@ -0,0 +1,907 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2016-2017 Linaro Ltd., Rob Herring <robh@kernel.org>
+ *
+ * Based on drivers/spmi/spmi.c:
+ * Copyright (c) 2012-2015, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/acpi.h>
+#include <linux/errno.h>
+#include <linux/idr.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_graph.h>
+#include <linux/of_device.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
+#include <linux/property.h>
+#include <linux/sched.h>
+#include <linux/serdev.h>
+#include <linux/slab.h>
+
+#include <linux/platform_data/x86/apple.h>
+
+static bool is_registered;
+static DEFINE_IDA(ctrl_ida);
+
+static ssize_t modalias_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	int len;
+
+	len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
+	if (len != -ENODEV)
+		return len;
+
+	return of_device_modalias(dev, buf, PAGE_SIZE);
+}
+static DEVICE_ATTR_RO(modalias);
+
+static struct attribute *serdev_device_attrs[] = {
+	&dev_attr_modalias.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(serdev_device);
+
+static int serdev_device_uevent(const struct device *dev, struct kobj_uevent_env *env)
+{
+	int rc;
+
+	/* TODO: platform modalias */
+
+	rc = acpi_device_uevent_modalias(dev, env);
+	if (rc != -ENODEV)
+		return rc;
+
+	return of_device_uevent_modalias(dev, env);
+}
+
+static void serdev_device_release(struct device *dev)
+{
+	struct serdev_device *serdev = to_serdev_device(dev);
+	kfree(serdev);
+}
+
+static const struct device_type serdev_device_type = {
+	.groups		= serdev_device_groups,
+	.uevent		= serdev_device_uevent,
+	.release	= serdev_device_release,
+};
+
+static bool is_serdev_device(const struct device *dev)
+{
+	return dev->type == &serdev_device_type;
+}
+
+static void serdev_ctrl_release(struct device *dev)
+{
+	struct serdev_controller *ctrl = to_serdev_controller(dev);
+	ida_free(&ctrl_ida, ctrl->nr);
+	kfree(ctrl);
+}
+
+static const struct device_type serdev_ctrl_type = {
+	.release	= serdev_ctrl_release,
+};
+
+static int serdev_device_match(struct device *dev, const struct device_driver *drv)
+{
+	if (!is_serdev_device(dev))
+		return 0;
+
+	/* TODO: platform matching */
+	if (acpi_driver_match_device(dev, drv))
+		return 1;
+
+	return of_driver_match_device(dev, drv);
+}
+
+/**
+ * serdev_device_add() - add a device previously constructed via serdev_device_alloc()
+ * @serdev:	serdev_device to be added
+ */
+int serdev_device_add(struct serdev_device *serdev)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+	struct device *parent = serdev->dev.parent;
+	int err;
+
+	dev_set_name(&serdev->dev, "%s-%d", dev_name(parent), serdev->nr);
+
+	/* Only a single slave device is currently supported. */
+	if (ctrl->serdev) {
+		dev_err(&serdev->dev, "controller busy\n");
+		return -EBUSY;
+	}
+	ctrl->serdev = serdev;
+
+	err = device_add(&serdev->dev);
+	if (err < 0) {
+		dev_err(&serdev->dev, "Failed to add serdev: %d\n", err);
+		goto err_clear_serdev;
+	}
+
+	dev_dbg(&serdev->dev, "serdev registered successfully\n");
+
+	return 0;
+
+err_clear_serdev:
+	ctrl->serdev = NULL;
+	return err;
+}
+EXPORT_SYMBOL_GPL(serdev_device_add);
+
+/**
+ * serdev_device_remove(): remove an serdev device
+ * @serdev:	serdev_device to be removed
+ */
+void serdev_device_remove(struct serdev_device *serdev)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+
+	device_unregister(&serdev->dev);
+	ctrl->serdev = NULL;
+}
+EXPORT_SYMBOL_GPL(serdev_device_remove);
+
+int serdev_device_open(struct serdev_device *serdev)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+	int ret;
+
+	if (!ctrl || !ctrl->ops->open)
+		return -EINVAL;
+
+	ret = ctrl->ops->open(ctrl);
+	if (ret)
+		return ret;
+
+	ret = pm_runtime_get_sync(&ctrl->dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(&ctrl->dev);
+		goto err_close;
+	}
+
+	return 0;
+
+err_close:
+	if (ctrl->ops->close)
+		ctrl->ops->close(ctrl);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(serdev_device_open);
+
+void serdev_device_close(struct serdev_device *serdev)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+
+	if (!ctrl || !ctrl->ops->close)
+		return;
+
+	pm_runtime_put(&ctrl->dev);
+
+	ctrl->ops->close(ctrl);
+}
+EXPORT_SYMBOL_GPL(serdev_device_close);
+
+static void devm_serdev_device_close(void *serdev)
+{
+	serdev_device_close(serdev);
+}
+
+int devm_serdev_device_open(struct device *dev, struct serdev_device *serdev)
+{
+	int ret;
+
+	ret = serdev_device_open(serdev);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(dev, devm_serdev_device_close, serdev);
+}
+EXPORT_SYMBOL_GPL(devm_serdev_device_open);
+
+void serdev_device_write_wakeup(struct serdev_device *serdev)
+{
+	complete(&serdev->write_comp);
+}
+EXPORT_SYMBOL_GPL(serdev_device_write_wakeup);
+
+/**
+ * serdev_device_write_buf() - write data asynchronously
+ * @serdev:	serdev device
+ * @buf:	data to be written
+ * @count:	number of bytes to write
+ *
+ * Write data to the device asynchronously.
+ *
+ * Note that any accepted data has only been buffered by the controller; use
+ * serdev_device_wait_until_sent() to make sure the controller write buffer
+ * has actually been emptied.
+ *
+ * Return: The number of bytes written (less than count if not enough room in
+ * the write buffer), or a negative errno on errors.
+ */
+int serdev_device_write_buf(struct serdev_device *serdev, const u8 *buf, size_t count)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+
+	if (!ctrl || !ctrl->ops->write_buf)
+		return -EINVAL;
+
+	return ctrl->ops->write_buf(ctrl, buf, count);
+}
+EXPORT_SYMBOL_GPL(serdev_device_write_buf);
+
+/**
+ * serdev_device_write() - write data synchronously
+ * @serdev:	serdev device
+ * @buf:	data to be written
+ * @count:	number of bytes to write
+ * @timeout:	timeout in jiffies, or 0 to wait indefinitely
+ *
+ * Write data to the device synchronously by repeatedly calling
+ * serdev_device_write() until the controller has accepted all data (unless
+ * interrupted by a timeout or a signal).
+ *
+ * Note that any accepted data has only been buffered by the controller; use
+ * serdev_device_wait_until_sent() to make sure the controller write buffer
+ * has actually been emptied.
+ *
+ * Note that this function depends on serdev_device_write_wakeup() being
+ * called in the serdev driver write_wakeup() callback.
+ *
+ * Return: The number of bytes written (less than count if interrupted),
+ * -ETIMEDOUT or -ERESTARTSYS if interrupted before any bytes were written, or
+ * a negative errno on errors.
+ */
+ssize_t serdev_device_write(struct serdev_device *serdev, const u8 *buf,
+			    size_t count, long timeout)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+	size_t written = 0;
+	ssize_t ret;
+
+	if (!ctrl || !ctrl->ops->write_buf || !serdev->ops->write_wakeup)
+		return -EINVAL;
+
+	if (timeout == 0)
+		timeout = MAX_SCHEDULE_TIMEOUT;
+
+	mutex_lock(&serdev->write_lock);
+	do {
+		reinit_completion(&serdev->write_comp);
+
+		ret = ctrl->ops->write_buf(ctrl, buf, count);
+		if (ret < 0)
+			break;
+
+		written += ret;
+		buf += ret;
+		count -= ret;
+
+		if (count == 0)
+			break;
+
+		timeout = wait_for_completion_interruptible_timeout(&serdev->write_comp,
+								    timeout);
+	} while (timeout > 0);
+	mutex_unlock(&serdev->write_lock);
+
+	if (ret < 0)
+		return ret;
+
+	if (timeout <= 0 && written == 0) {
+		if (timeout == -ERESTARTSYS)
+			return -ERESTARTSYS;
+		else
+			return -ETIMEDOUT;
+	}
+
+	return written;
+}
+EXPORT_SYMBOL_GPL(serdev_device_write);
+
+void serdev_device_write_flush(struct serdev_device *serdev)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+
+	if (!ctrl || !ctrl->ops->write_flush)
+		return;
+
+	ctrl->ops->write_flush(ctrl);
+}
+EXPORT_SYMBOL_GPL(serdev_device_write_flush);
+
+unsigned int serdev_device_set_baudrate(struct serdev_device *serdev, unsigned int speed)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+
+	if (!ctrl || !ctrl->ops->set_baudrate)
+		return 0;
+
+	return ctrl->ops->set_baudrate(ctrl, speed);
+
+}
+EXPORT_SYMBOL_GPL(serdev_device_set_baudrate);
+
+void serdev_device_set_flow_control(struct serdev_device *serdev, bool enable)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+
+	if (!ctrl || !ctrl->ops->set_flow_control)
+		return;
+
+	ctrl->ops->set_flow_control(ctrl, enable);
+}
+EXPORT_SYMBOL_GPL(serdev_device_set_flow_control);
+
+int serdev_device_set_parity(struct serdev_device *serdev,
+			     enum serdev_parity parity)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+
+	if (!ctrl || !ctrl->ops->set_parity)
+		return -EOPNOTSUPP;
+
+	return ctrl->ops->set_parity(ctrl, parity);
+}
+EXPORT_SYMBOL_GPL(serdev_device_set_parity);
+
+void serdev_device_wait_until_sent(struct serdev_device *serdev, long timeout)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+
+	if (!ctrl || !ctrl->ops->wait_until_sent)
+		return;
+
+	ctrl->ops->wait_until_sent(ctrl, timeout);
+}
+EXPORT_SYMBOL_GPL(serdev_device_wait_until_sent);
+
+int serdev_device_get_tiocm(struct serdev_device *serdev)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+
+	if (!ctrl || !ctrl->ops->get_tiocm)
+		return -EOPNOTSUPP;
+
+	return ctrl->ops->get_tiocm(ctrl);
+}
+EXPORT_SYMBOL_GPL(serdev_device_get_tiocm);
+
+int serdev_device_set_tiocm(struct serdev_device *serdev, int set, int clear)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+
+	if (!ctrl || !ctrl->ops->set_tiocm)
+		return -EOPNOTSUPP;
+
+	return ctrl->ops->set_tiocm(ctrl, set, clear);
+}
+EXPORT_SYMBOL_GPL(serdev_device_set_tiocm);
+
+int serdev_device_break_ctl(struct serdev_device *serdev, int break_state)
+{
+	struct serdev_controller *ctrl = serdev->ctrl;
+
+	if (!ctrl || !ctrl->ops->break_ctl)
+		return -EOPNOTSUPP;
+
+	return ctrl->ops->break_ctl(ctrl, break_state);
+}
+EXPORT_SYMBOL_GPL(serdev_device_break_ctl);
+
+static int serdev_drv_probe(struct device *dev)
+{
+	const struct serdev_device_driver *sdrv = to_serdev_device_driver(dev->driver);
+	int ret;
+
+	ret = dev_pm_domain_attach(dev, PD_FLAG_ATTACH_POWER_ON |
+					PD_FLAG_DETACH_POWER_OFF);
+	if (ret)
+		return ret;
+
+	return sdrv->probe(to_serdev_device(dev));
+}
+
+static void serdev_drv_remove(struct device *dev)
+{
+	const struct serdev_device_driver *sdrv = to_serdev_device_driver(dev->driver);
+	if (sdrv->remove)
+		sdrv->remove(to_serdev_device(dev));
+}
+
+static void serdev_drv_shutdown(struct device *dev)
+{
+	const struct serdev_device_driver *sdrv =
+		to_serdev_device_driver(dev->driver);
+
+	if (dev->driver && sdrv->shutdown)
+		sdrv->shutdown(to_serdev_device(dev));
+}
+
+static const struct bus_type serdev_bus_type = {
+	.name		= "serial",
+	.match		= serdev_device_match,
+	.probe		= serdev_drv_probe,
+	.remove		= serdev_drv_remove,
+	.shutdown	= serdev_drv_shutdown,
+};
+
+/**
+ * serdev_device_alloc() - Allocate a new serdev device
+ * @ctrl:	associated controller
+ *
+ * Caller is responsible for either calling serdev_device_add() to add the
+ * newly allocated controller, or calling serdev_device_put() to discard it.
+ */
+struct serdev_device *serdev_device_alloc(struct serdev_controller *ctrl)
+{
+	struct serdev_device *serdev;
+
+	serdev = kzalloc_obj(*serdev);
+	if (!serdev)
+		return NULL;
+
+	serdev->ctrl = ctrl;
+	device_initialize(&serdev->dev);
+	serdev->dev.parent = &ctrl->dev;
+	serdev->dev.bus = &serdev_bus_type;
+	serdev->dev.type = &serdev_device_type;
+	init_completion(&serdev->write_comp);
+	mutex_init(&serdev->write_lock);
+	return serdev;
+}
+EXPORT_SYMBOL_GPL(serdev_device_alloc);
+
+/**
+ * serdev_controller_alloc() - Allocate a new serdev controller
+ * @host:	serial port hardware controller device
+ * @parent:	parent device
+ * @size:	size of private data
+ *
+ * Caller is responsible for either calling serdev_controller_add() to add the
+ * newly allocated controller, or calling serdev_controller_put() to discard it.
+ * The allocated private data region may be accessed via
+ * serdev_controller_get_drvdata()
+ */
+struct serdev_controller *serdev_controller_alloc(struct device *host,
+						  struct device *parent,
+						  size_t size)
+{
+	struct serdev_controller *ctrl;
+	int id;
+
+	if (WARN_ON(!parent))
+		return NULL;
+
+	ctrl = kzalloc(sizeof(*ctrl) + size, GFP_KERNEL);
+	if (!ctrl)
+		return NULL;
+
+	id = ida_alloc(&ctrl_ida, GFP_KERNEL);
+	if (id < 0) {
+		dev_err(parent,
+			"unable to allocate serdev controller identifier.\n");
+		goto err_free;
+	}
+
+	ctrl->nr = id;
+
+	device_initialize(&ctrl->dev);
+	ctrl->dev.type = &serdev_ctrl_type;
+	ctrl->dev.bus = &serdev_bus_type;
+	ctrl->dev.parent = parent;
+	ctrl->host = host;
+	device_set_node(&ctrl->dev, dev_fwnode(host));
+	serdev_controller_set_drvdata(ctrl, &ctrl[1]);
+
+	dev_set_name(&ctrl->dev, "serial%d", id);
+
+	pm_runtime_no_callbacks(&ctrl->dev);
+	pm_suspend_ignore_children(&ctrl->dev, true);
+
+	dev_dbg(&ctrl->dev, "allocated controller 0x%p id %d\n", ctrl, id);
+	return ctrl;
+
+err_free:
+	kfree(ctrl);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(serdev_controller_alloc);
+
+#ifdef CONFIG_OF
+/**
+ * of_find_serdev_controller_by_node() - Find the serdev controller associated
+ *					 with the devicetree node
+ * @node:	Devicetree node
+ *
+ * Return: Pointer to the serdev controller associated with the node. NULL if
+ * the controller is not found. Caller is responsible for calling
+ * serdev_controller_put() to drop the reference.
+ */
+struct serdev_controller *of_find_serdev_controller_by_node(struct device_node *node)
+{
+	struct device *dev = bus_find_device_by_of_node(&serdev_bus_type, node);
+
+	return (dev && dev->type == &serdev_ctrl_type) ? to_serdev_controller(dev) : NULL;
+}
+EXPORT_SYMBOL_GPL(of_find_serdev_controller_by_node);
+#endif
+
+static int of_serdev_register_devices(struct serdev_controller *ctrl)
+{
+	struct device_node *node;
+	struct serdev_device *serdev = NULL;
+	int err;
+	bool found = false;
+
+	for_each_available_child_of_node(ctrl->dev.of_node, node) {
+		if (!of_property_present(node, "compatible"))
+			continue;
+
+		dev_dbg(&ctrl->dev, "adding child %pOF\n", node);
+
+		serdev = serdev_device_alloc(ctrl);
+		if (!serdev)
+			continue;
+
+		device_set_node(&serdev->dev, of_fwnode_handle(node));
+
+		err = serdev_device_add(serdev);
+		if (err) {
+			dev_err(&serdev->dev,
+				"failure adding device. status %pe\n",
+				ERR_PTR(err));
+			serdev_device_put(serdev);
+		} else
+			found = true;
+	}
+
+	/*
+	 * When the serdev controller is connected to an external connector like
+	 * M.2 in DT, then the serdev devices may be created dynamically by the
+	 * connector driver.
+	 */
+	if (!found && !of_graph_is_present(dev_of_node(&ctrl->dev)))
+		return -ENODEV;
+
+	return 0;
+}
+
+#ifdef CONFIG_ACPI
+
+#define SERDEV_ACPI_MAX_SCAN_DEPTH 32
+
+struct acpi_serdev_lookup {
+	acpi_handle device_handle;
+	acpi_handle controller_handle;
+	int n;
+	int index;
+};
+
+/**
+ * serdev_acpi_get_uart_resource - Gets UARTSerialBus resource if type matches
+ * @ares:	ACPI resource
+ * @uart:	Pointer to UARTSerialBus resource will be returned here
+ *
+ * Checks if the given ACPI resource is of type UARTSerialBus.
+ * In this case, returns a pointer to it to the caller.
+ *
+ * Return: True if resource type is of UARTSerialBus, otherwise false.
+ */
+bool serdev_acpi_get_uart_resource(struct acpi_resource *ares,
+				   struct acpi_resource_uart_serialbus **uart)
+{
+	struct acpi_resource_uart_serialbus *sb;
+
+	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
+		return false;
+
+	sb = &ares->data.uart_serial_bus;
+	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_UART)
+		return false;
+
+	*uart = sb;
+	return true;
+}
+EXPORT_SYMBOL_GPL(serdev_acpi_get_uart_resource);
+
+static int acpi_serdev_parse_resource(struct acpi_resource *ares, void *data)
+{
+	struct acpi_serdev_lookup *lookup = data;
+	struct acpi_resource_uart_serialbus *sb;
+	acpi_status status;
+
+	if (!serdev_acpi_get_uart_resource(ares, &sb))
+		return 1;
+
+	if (lookup->index != -1 && lookup->n++ != lookup->index)
+		return 1;
+
+	status = acpi_get_handle(lookup->device_handle,
+				 sb->resource_source.string_ptr,
+				 &lookup->controller_handle);
+	if (ACPI_FAILURE(status))
+		return 1;
+
+	/*
+	 * NOTE: Ideally, we would also want to retrieve other properties here,
+	 * once setting them before opening the device is supported by serdev.
+	 */
+
+	return 1;
+}
+
+static int acpi_serdev_do_lookup(struct acpi_device *adev,
+                                 struct acpi_serdev_lookup *lookup)
+{
+	struct list_head resource_list;
+	int ret;
+
+	lookup->device_handle = acpi_device_handle(adev);
+	lookup->controller_handle = NULL;
+	lookup->n = 0;
+
+	INIT_LIST_HEAD(&resource_list);
+	ret = acpi_dev_get_resources(adev, &resource_list,
+				     acpi_serdev_parse_resource, lookup);
+	if (ret < 0)
+		return -EINVAL;
+
+	acpi_dev_free_resource_list(&resource_list);
+
+	return 0;
+}
+
+static int acpi_serdev_check_resources(struct serdev_controller *ctrl,
+				       struct acpi_device *adev)
+{
+	struct acpi_serdev_lookup lookup;
+	int ret;
+
+	if (acpi_bus_get_status(adev) || !adev->status.present)
+		return -EINVAL;
+
+	/* Look for UARTSerialBusV2 resource */
+	lookup.index = -1;	// we only care for the last device
+
+	ret = acpi_serdev_do_lookup(adev, &lookup);
+	if (ret)
+		return ret;
+
+	/*
+	 * Apple machines provide an empty resource template, so on those
+	 * machines just look for immediate children with a "baud" property
+	 * (from the _DSM method) instead.
+	 */
+	if (!lookup.controller_handle && x86_apple_machine &&
+	    !acpi_dev_get_property(adev, "baud", ACPI_TYPE_BUFFER, NULL))
+		acpi_get_parent(adev->handle, &lookup.controller_handle);
+
+	/* Make sure controller and ResourceSource handle match */
+	if (!device_match_acpi_handle(ctrl->host, lookup.controller_handle))
+		return -ENODEV;
+
+	return 0;
+}
+
+static acpi_status acpi_serdev_register_device(struct serdev_controller *ctrl,
+					       struct acpi_device *adev)
+{
+	struct serdev_device *serdev;
+	int err;
+
+	serdev = serdev_device_alloc(ctrl);
+	if (!serdev) {
+		dev_err(&ctrl->dev, "failed to allocate serdev device for %s\n",
+			dev_name(&adev->dev));
+		return AE_NO_MEMORY;
+	}
+
+	ACPI_COMPANION_SET(&serdev->dev, adev);
+	acpi_device_set_enumerated(adev);
+
+	err = serdev_device_add(serdev);
+	if (err) {
+		dev_err(&serdev->dev,
+			"failure adding ACPI serdev device. status %pe\n",
+			ERR_PTR(err));
+		serdev_device_put(serdev);
+	}
+
+	return AE_OK;
+}
+
+static const struct acpi_device_id serdev_acpi_devices_blacklist[] = {
+	{ "INT3511", 0 },
+	{ "INT3512", 0 },
+	{ },
+};
+
+static acpi_status acpi_serdev_add_device(acpi_handle handle, u32 level,
+					  void *data, void **return_value)
+{
+	struct acpi_device *adev = acpi_fetch_acpi_dev(handle);
+	struct serdev_controller *ctrl = data;
+
+	if (!adev || acpi_device_enumerated(adev))
+		return AE_OK;
+
+	/* Skip if black listed */
+	if (!acpi_match_device_ids(adev, serdev_acpi_devices_blacklist))
+		return AE_OK;
+
+	if (acpi_serdev_check_resources(ctrl, adev))
+		return AE_OK;
+
+	return acpi_serdev_register_device(ctrl, adev);
+}
+
+
+static int acpi_serdev_register_devices(struct serdev_controller *ctrl)
+{
+	acpi_status status;
+	bool skip;
+	int ret;
+
+	if (!has_acpi_companion(ctrl->host))
+		return -ENODEV;
+
+	/*
+	 * Skip registration on boards where the ACPI tables are known to
+	 * contain buggy devices. Note serdev_controller_add() must still
+	 * succeed in this case, so that the proper serdev devices can be
+	 * added "manually" later.
+	 */
+	ret = acpi_quirk_skip_serdev_enumeration(ctrl->host, &skip);
+	if (ret)
+		return ret;
+	if (skip)
+		return 0;
+
+	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
+				     SERDEV_ACPI_MAX_SCAN_DEPTH,
+				     acpi_serdev_add_device, NULL, ctrl, NULL);
+	if (ACPI_FAILURE(status))
+		dev_warn(&ctrl->dev, "failed to enumerate serdev slaves\n");
+
+	if (!ctrl->serdev)
+		return -ENODEV;
+
+	return 0;
+}
+#else
+static inline int acpi_serdev_register_devices(struct serdev_controller *ctrl)
+{
+	return -ENODEV;
+}
+#endif /* CONFIG_ACPI */
+
+/**
+ * serdev_controller_add() - Add an serdev controller
+ * @ctrl:	controller to be registered.
+ *
+ * Register a controller previously allocated via serdev_controller_alloc() with
+ * the serdev core.
+ */
+int serdev_controller_add(struct serdev_controller *ctrl)
+{
+	int ret_of, ret_acpi, ret;
+
+	/* Can't register until after driver model init */
+	if (WARN_ON(!is_registered))
+		return -EAGAIN;
+
+	ret = device_add(&ctrl->dev);
+	if (ret)
+		return ret;
+
+	pm_runtime_enable(&ctrl->dev);
+
+	ret_of = of_serdev_register_devices(ctrl);
+	ret_acpi = acpi_serdev_register_devices(ctrl);
+	if (ret_of && ret_acpi) {
+		dev_dbg(&ctrl->dev, "no devices registered: of:%pe acpi:%pe\n",
+			ERR_PTR(ret_of), ERR_PTR(ret_acpi));
+		ret = -ENODEV;
+		goto err_rpm_disable;
+	}
+
+	dev_dbg(&ctrl->dev, "serdev controller registered: dev:%p\n", &ctrl->dev);
+	return 0;
+
+err_rpm_disable:
+	pm_runtime_disable(&ctrl->dev);
+	device_del(&ctrl->dev);
+	return ret;
+};
+EXPORT_SYMBOL_GPL(serdev_controller_add);
+
+/* Remove a device associated with a controller */
+static int serdev_remove_device(struct device *dev, void *data)
+{
+	struct serdev_device *serdev = to_serdev_device(dev);
+	if (dev->type == &serdev_device_type)
+		serdev_device_remove(serdev);
+	return 0;
+}
+
+/**
+ * serdev_controller_remove(): remove an serdev controller
+ * @ctrl:	controller to remove
+ *
+ * Remove a serdev controller.  Caller is responsible for calling
+ * serdev_controller_put() to discard the allocated controller.
+ */
+void serdev_controller_remove(struct serdev_controller *ctrl)
+{
+	if (!ctrl)
+		return;
+
+	device_for_each_child(&ctrl->dev, NULL, serdev_remove_device);
+	pm_runtime_disable(&ctrl->dev);
+	device_del(&ctrl->dev);
+}
+EXPORT_SYMBOL_GPL(serdev_controller_remove);
+
+static void serdev_legacy_shutdown(struct serdev_device *serdev)
+{
+	struct device *dev = &serdev->dev;
+	struct device_driver *driver = dev->driver;
+
+	driver->shutdown(dev);
+}
+
+/**
+ * __serdev_device_driver_register() - Register client driver with serdev core
+ * @sdrv:	client driver to be associated with client-device.
+ * @owner:	client driver owner to set.
+ *
+ * This API will register the client driver with the serdev framework.
+ * It is typically called from the driver's module-init function.
+ */
+int __serdev_device_driver_register(struct serdev_device_driver *sdrv, struct module *owner)
+{
+	sdrv->driver.bus = &serdev_bus_type;
+	sdrv->driver.owner = owner;
+
+	/* force drivers to async probe so I/O is possible in probe */
+        sdrv->driver.probe_type = PROBE_PREFER_ASYNCHRONOUS;
+
+	if (!sdrv->shutdown && sdrv->driver.shutdown)
+		sdrv->shutdown = serdev_legacy_shutdown;
+
+	return driver_register(&sdrv->driver);
+}
+EXPORT_SYMBOL_GPL(__serdev_device_driver_register);
+
+static void __exit serdev_exit(void)
+{
+	bus_unregister(&serdev_bus_type);
+	ida_destroy(&ctrl_ida);
+}
+module_exit(serdev_exit);
+
+static int __init serdev_init(void)
+{
+	int ret;
+
+	ret = bus_register(&serdev_bus_type);
+	if (ret)
+		return ret;
+
+	is_registered = true;
+	return 0;
+}
+/* Must be before serial drivers register */
+postcore_initcall(serdev_init);
+
+MODULE_AUTHOR("Rob Herring <robh@kernel.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Serial attached device bus");
diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c
new file mode 100644
index 000000000..bab1b143b
--- /dev/null
+++ b/drivers/tty/serdev/serdev-ttyport.c
@@ -0,0 +1,320 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2016-2017 Linaro Ltd., Rob Herring <robh@kernel.org>
+ */
+#include <linux/kernel.h>
+#include <linux/serdev.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/poll.h>
+
+#define SERPORT_ACTIVE		1
+
+struct serport {
+	struct tty_port *port;
+	struct tty_struct *tty;
+	struct tty_driver *tty_drv;
+	int tty_idx;
+	unsigned long flags;
+};
+
+/*
+ * Callback functions from the tty port.
+ */
+
+static size_t ttyport_receive_buf(struct tty_port *port, const u8 *cp,
+				  const u8 *fp, size_t count)
+{
+	struct serdev_controller *ctrl = port->client_data;
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	size_t ret;
+
+	if (!test_bit(SERPORT_ACTIVE, &serport->flags))
+		return 0;
+
+	ret = serdev_controller_receive_buf(ctrl, cp, count);
+
+	dev_WARN_ONCE(&ctrl->dev, ret > count,
+				"receive_buf returns %zu (count = %zu)\n",
+				ret, count);
+	if (ret > count)
+		return count;
+
+	return ret;
+}
+
+static void ttyport_write_wakeup(struct tty_port *port)
+{
+	struct serdev_controller *ctrl = port->client_data;
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty;
+
+	tty = tty_port_tty_get(port);
+	if (!tty)
+		return;
+
+	if (test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags) &&
+	    test_bit(SERPORT_ACTIVE, &serport->flags))
+		serdev_controller_write_wakeup(ctrl);
+
+	/* Wake up any tty_wait_until_sent() */
+	wake_up_interruptible(&tty->write_wait);
+
+	tty_kref_put(tty);
+}
+
+static const struct tty_port_client_operations client_ops = {
+	.receive_buf = ttyport_receive_buf,
+	.write_wakeup = ttyport_write_wakeup,
+};
+
+/*
+ * Callback functions from the serdev core.
+ */
+
+static ssize_t ttyport_write_buf(struct serdev_controller *ctrl, const u8 *data, size_t len)
+{
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty = serport->tty;
+
+	if (!test_bit(SERPORT_ACTIVE, &serport->flags))
+		return 0;
+
+	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+	return tty->ops->write(serport->tty, data, len);
+}
+
+static void ttyport_write_flush(struct serdev_controller *ctrl)
+{
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty = serport->tty;
+
+	tty_driver_flush_buffer(tty);
+}
+
+static int ttyport_open(struct serdev_controller *ctrl)
+{
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty;
+	struct ktermios ktermios;
+	int ret;
+
+	tty = tty_init_dev(serport->tty_drv, serport->tty_idx);
+	if (IS_ERR(tty))
+		return PTR_ERR(tty);
+	serport->tty = tty;
+
+	if (!tty->ops->open || !tty->ops->close) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	ret = tty->ops->open(serport->tty, NULL);
+	if (ret)
+		goto err_close;
+
+	tty_unlock(serport->tty);
+
+	/* Bring the UART into a known 8 bits no parity hw fc state */
+	ktermios = tty->termios;
+	ktermios.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP |
+			      INLCR | IGNCR | ICRNL | IXON);
+	ktermios.c_oflag &= ~OPOST;
+	ktermios.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
+	ktermios.c_cflag &= ~(CSIZE | PARENB);
+	ktermios.c_cflag |= CS8;
+	ktermios.c_cflag |= CRTSCTS;
+	/* Hangups are not supported so make sure to ignore carrier detect. */
+	ktermios.c_cflag |= CLOCAL;
+	tty_set_termios(tty, &ktermios);
+
+	set_bit(SERPORT_ACTIVE, &serport->flags);
+
+	return 0;
+
+err_close:
+	tty->ops->close(tty, NULL);
+err_unlock:
+	tty_unlock(tty);
+	tty_release_struct(tty, serport->tty_idx);
+
+	return ret;
+}
+
+static void ttyport_close(struct serdev_controller *ctrl)
+{
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty = serport->tty;
+
+	clear_bit(SERPORT_ACTIVE, &serport->flags);
+
+	tty_lock(tty);
+	if (tty->ops->close)
+		tty->ops->close(tty, NULL);
+	tty_unlock(tty);
+
+	tty_release_struct(tty, serport->tty_idx);
+}
+
+static unsigned int ttyport_set_baudrate(struct serdev_controller *ctrl, unsigned int speed)
+{
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty = serport->tty;
+	struct ktermios ktermios = tty->termios;
+
+	ktermios.c_cflag &= ~CBAUD;
+	tty_termios_encode_baud_rate(&ktermios, speed, speed);
+
+	/* tty_set_termios() return not checked as it is always 0 */
+	tty_set_termios(tty, &ktermios);
+	return ktermios.c_ospeed;
+}
+
+static void ttyport_set_flow_control(struct serdev_controller *ctrl, bool enable)
+{
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty = serport->tty;
+	struct ktermios ktermios = tty->termios;
+
+	if (enable)
+		ktermios.c_cflag |= CRTSCTS;
+	else
+		ktermios.c_cflag &= ~CRTSCTS;
+
+	tty_set_termios(tty, &ktermios);
+}
+
+static int ttyport_set_parity(struct serdev_controller *ctrl,
+			      enum serdev_parity parity)
+{
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty = serport->tty;
+	struct ktermios ktermios = tty->termios;
+
+	ktermios.c_cflag &= ~(PARENB | PARODD | CMSPAR);
+	if (parity != SERDEV_PARITY_NONE) {
+		ktermios.c_cflag |= PARENB;
+		if (parity == SERDEV_PARITY_ODD)
+			ktermios.c_cflag |= PARODD;
+	}
+
+	tty_set_termios(tty, &ktermios);
+
+	if ((tty->termios.c_cflag & (PARENB | PARODD | CMSPAR)) !=
+	    (ktermios.c_cflag & (PARENB | PARODD | CMSPAR)))
+		return -EINVAL;
+
+	return 0;
+}
+
+static void ttyport_wait_until_sent(struct serdev_controller *ctrl, long timeout)
+{
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty = serport->tty;
+
+	tty_wait_until_sent(tty, timeout);
+}
+
+static int ttyport_get_tiocm(struct serdev_controller *ctrl)
+{
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty = serport->tty;
+
+	if (!tty->ops->tiocmget)
+		return -EOPNOTSUPP;
+
+	return tty->ops->tiocmget(tty);
+}
+
+static int ttyport_set_tiocm(struct serdev_controller *ctrl, unsigned int set, unsigned int clear)
+{
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty = serport->tty;
+
+	if (!tty->ops->tiocmset)
+		return -EOPNOTSUPP;
+
+	return tty->ops->tiocmset(tty, set, clear);
+}
+
+static int ttyport_break_ctl(struct serdev_controller *ctrl, unsigned int break_state)
+{
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+	struct tty_struct *tty = serport->tty;
+
+	if (!tty->ops->break_ctl)
+		return -EOPNOTSUPP;
+
+	return tty->ops->break_ctl(tty, break_state);
+}
+
+static const struct serdev_controller_ops ctrl_ops = {
+	.write_buf = ttyport_write_buf,
+	.write_flush = ttyport_write_flush,
+	.open = ttyport_open,
+	.close = ttyport_close,
+	.set_flow_control = ttyport_set_flow_control,
+	.set_parity = ttyport_set_parity,
+	.set_baudrate = ttyport_set_baudrate,
+	.wait_until_sent = ttyport_wait_until_sent,
+	.get_tiocm = ttyport_get_tiocm,
+	.set_tiocm = ttyport_set_tiocm,
+	.break_ctl = ttyport_break_ctl,
+};
+
+struct device *serdev_tty_port_register(struct tty_port *port,
+					struct device *host,
+					struct device *parent,
+					struct tty_driver *drv, int idx)
+{
+	struct serdev_controller *ctrl;
+	struct serport *serport;
+	int ret;
+
+	if (!port || !drv || !parent)
+		return ERR_PTR(-ENODEV);
+
+	ctrl = serdev_controller_alloc(host, parent, sizeof(struct serport));
+	if (!ctrl)
+		return ERR_PTR(-ENOMEM);
+	serport = serdev_controller_get_drvdata(ctrl);
+
+	serport->port = port;
+	serport->tty_idx = idx;
+	serport->tty_drv = drv;
+
+	ctrl->ops = &ctrl_ops;
+
+	port->client_ops = &client_ops;
+	port->client_data = ctrl;
+
+	ret = serdev_controller_add(ctrl);
+	if (ret)
+		goto err_reset_data;
+
+	dev_info(&ctrl->dev, "tty port %s%d registered\n", drv->name, idx);
+	return &ctrl->dev;
+
+err_reset_data:
+	port->client_data = NULL;
+	port->client_ops = &tty_port_default_client_ops;
+	serdev_controller_put(ctrl);
+
+	return ERR_PTR(ret);
+}
+
+int serdev_tty_port_unregister(struct tty_port *port)
+{
+	struct serdev_controller *ctrl = port->client_data;
+	struct serport *serport = serdev_controller_get_drvdata(ctrl);
+
+	if (!serport)
+		return -ENODEV;
+
+	serdev_controller_remove(ctrl);
+	port->client_data = NULL;
+	port->client_ops = &tty_port_default_client_ops;
+	serdev_controller_put(ctrl);
+
+	return 0;
+}