Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

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;
+}