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
  ...

9 files changed, 1933 insertions, 0 deletions

diff --git a/drivers/gnss/Kconfig b/drivers/gnss/Kconfig
new file mode 100644
index 000000000..d7fe265c2
--- /dev/null
+++ b/drivers/gnss/Kconfig
@@ -0,0 +1,68 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# GNSS receiver configuration
+#
+
+menuconfig GNSS
+	tristate "GNSS receiver support"
+	help
+	  Say Y here if you have a GNSS receiver (e.g. a GPS receiver).
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called gnss.
+
+if GNSS
+
+config GNSS_SERIAL
+	tristate
+
+config GNSS_MTK_SERIAL
+	tristate "Mediatek GNSS receiver support"
+	depends on SERIAL_DEV_BUS
+	select GNSS_SERIAL
+	help
+	  Say Y here if you have a Mediatek-based GNSS receiver which uses a
+	  serial interface.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called gnss-mtk.
+
+	  If unsure, say N.
+
+config GNSS_SIRF_SERIAL
+	tristate "SiRFstar GNSS receiver support"
+	depends on SERIAL_DEV_BUS
+	help
+	  Say Y here if you have a SiRFstar-based GNSS receiver which uses a
+	  serial interface.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called gnss-sirf.
+
+	  If unsure, say N.
+
+config GNSS_UBX_SERIAL
+	tristate "u-blox GNSS receiver support"
+	depends on SERIAL_DEV_BUS
+	select GNSS_SERIAL
+	help
+	  Say Y here if you have a u-blox GNSS receiver which uses a serial
+	  interface.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called gnss-ubx.
+
+	  If unsure, say N.
+
+config GNSS_USB
+	tristate "USB GNSS receiver support"
+	depends on USB
+	help
+	  Say Y here if you have a GNSS receiver which uses a USB interface.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called gnss-usb.
+
+	  If unsure, say N.
+
+endif # GNSS
diff --git a/drivers/gnss/Makefile b/drivers/gnss/Makefile
new file mode 100644
index 000000000..bb2cbada3
--- /dev/null
+++ b/drivers/gnss/Makefile
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the GNSS subsystem.
+#
+
+obj-$(CONFIG_GNSS)			+= gnss.o
+gnss-y := core.o
+
+obj-$(CONFIG_GNSS_SERIAL)		+= gnss-serial.o
+gnss-serial-y := serial.o
+
+obj-$(CONFIG_GNSS_MTK_SERIAL)		+= gnss-mtk.o
+gnss-mtk-y := mtk.o
+
+obj-$(CONFIG_GNSS_SIRF_SERIAL)		+= gnss-sirf.o
+gnss-sirf-y := sirf.o
+
+obj-$(CONFIG_GNSS_UBX_SERIAL)		+= gnss-ubx.o
+gnss-ubx-y := ubx.o
+
+obj-$(CONFIG_GNSS_USB)			+= gnss-usb.o
+gnss-usb-y := usb.o
diff --git a/drivers/gnss/core.c b/drivers/gnss/core.c
new file mode 100644
index 000000000..006f5533e
--- /dev/null
+++ b/drivers/gnss/core.c
@@ -0,0 +1,420 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * GNSS receiver core
+ *
+ * Copyright (C) 2018 Johan Hovold <johan@kernel.org>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cdev.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/gnss.h>
+#include <linux/idr.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/wait.h>
+
+#define GNSS_FLAG_HAS_WRITE_RAW		BIT(0)
+
+#define GNSS_MINORS	16
+
+static DEFINE_IDA(gnss_minors);
+static dev_t gnss_first;
+
+/* FIFO size must be a power of two */
+#define GNSS_READ_FIFO_SIZE	4096
+#define GNSS_WRITE_BUF_SIZE	1024
+
+#define to_gnss_device(d) container_of((d), struct gnss_device, dev)
+
+static int gnss_open(struct inode *inode, struct file *file)
+{
+	struct gnss_device *gdev;
+	int ret = 0;
+
+	gdev = container_of(inode->i_cdev, struct gnss_device, cdev);
+
+	get_device(&gdev->dev);
+
+	stream_open(inode, file);
+	file->private_data = gdev;
+
+	down_write(&gdev->rwsem);
+	if (gdev->disconnected) {
+		ret = -ENODEV;
+		goto unlock;
+	}
+
+	if (gdev->count++ == 0) {
+		ret = gdev->ops->open(gdev);
+		if (ret)
+			gdev->count--;
+	}
+unlock:
+	up_write(&gdev->rwsem);
+
+	if (ret)
+		put_device(&gdev->dev);
+
+	return ret;
+}
+
+static int gnss_release(struct inode *inode, struct file *file)
+{
+	struct gnss_device *gdev = file->private_data;
+
+	down_write(&gdev->rwsem);
+	if (gdev->disconnected)
+		goto unlock;
+
+	if (--gdev->count == 0) {
+		gdev->ops->close(gdev);
+		kfifo_reset(&gdev->read_fifo);
+	}
+unlock:
+	up_write(&gdev->rwsem);
+
+	put_device(&gdev->dev);
+
+	return 0;
+}
+
+static ssize_t gnss_read(struct file *file, char __user *buf,
+				size_t count, loff_t *pos)
+{
+	struct gnss_device *gdev = file->private_data;
+	unsigned int copied;
+	int ret;
+
+	mutex_lock(&gdev->read_mutex);
+	while (kfifo_is_empty(&gdev->read_fifo)) {
+		mutex_unlock(&gdev->read_mutex);
+
+		if (gdev->disconnected)
+			return 0;
+
+		if (file->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+
+		ret = wait_event_interruptible(gdev->read_queue,
+				gdev->disconnected ||
+				!kfifo_is_empty(&gdev->read_fifo));
+		if (ret)
+			return -ERESTARTSYS;
+
+		mutex_lock(&gdev->read_mutex);
+	}
+
+	ret = kfifo_to_user(&gdev->read_fifo, buf, count, &copied);
+	if (ret == 0)
+		ret = copied;
+
+	mutex_unlock(&gdev->read_mutex);
+
+	return ret;
+}
+
+static ssize_t gnss_write(struct file *file, const char __user *buf,
+				size_t count, loff_t *pos)
+{
+	struct gnss_device *gdev = file->private_data;
+	size_t written = 0;
+	int ret;
+
+	if (gdev->disconnected)
+		return -EIO;
+
+	if (!count)
+		return 0;
+
+	if (!(gdev->flags & GNSS_FLAG_HAS_WRITE_RAW))
+		return -EIO;
+
+	/* Ignoring O_NONBLOCK, write_raw() is synchronous. */
+
+	ret = mutex_lock_interruptible(&gdev->write_mutex);
+	if (ret)
+		return -ERESTARTSYS;
+
+	for (;;) {
+		size_t n = count - written;
+
+		if (n > GNSS_WRITE_BUF_SIZE)
+			n = GNSS_WRITE_BUF_SIZE;
+
+		if (copy_from_user(gdev->write_buf, buf, n)) {
+			ret = -EFAULT;
+			goto out_unlock;
+		}
+
+		/*
+		 * Assumes write_raw can always accept GNSS_WRITE_BUF_SIZE
+		 * bytes.
+		 *
+		 * FIXME: revisit
+		 */
+		down_read(&gdev->rwsem);
+		if (!gdev->disconnected)
+			ret = gdev->ops->write_raw(gdev, gdev->write_buf, n);
+		else
+			ret = -EIO;
+		up_read(&gdev->rwsem);
+
+		if (ret < 0)
+			break;
+
+		written += ret;
+		buf += ret;
+
+		if (written == count)
+			break;
+	}
+
+	if (written)
+		ret = written;
+out_unlock:
+	mutex_unlock(&gdev->write_mutex);
+
+	return ret;
+}
+
+static __poll_t gnss_poll(struct file *file, poll_table *wait)
+{
+	struct gnss_device *gdev = file->private_data;
+	__poll_t mask = 0;
+
+	poll_wait(file, &gdev->read_queue, wait);
+
+	if (!kfifo_is_empty(&gdev->read_fifo))
+		mask |= EPOLLIN | EPOLLRDNORM;
+	if (gdev->disconnected)
+		mask |= EPOLLHUP;
+
+	return mask;
+}
+
+static const struct file_operations gnss_fops = {
+	.owner		= THIS_MODULE,
+	.open		= gnss_open,
+	.release	= gnss_release,
+	.read		= gnss_read,
+	.write		= gnss_write,
+	.poll		= gnss_poll,
+};
+
+static struct class *gnss_class;
+
+static void gnss_device_release(struct device *dev)
+{
+	struct gnss_device *gdev = to_gnss_device(dev);
+
+	kfree(gdev->write_buf);
+	kfifo_free(&gdev->read_fifo);
+	ida_free(&gnss_minors, gdev->id);
+	kfree(gdev);
+}
+
+struct gnss_device *gnss_allocate_device(struct device *parent)
+{
+	struct gnss_device *gdev;
+	struct device *dev;
+	int id;
+	int ret;
+
+	gdev = kzalloc_obj(*gdev);
+	if (!gdev)
+		return NULL;
+
+	id = ida_alloc_max(&gnss_minors, GNSS_MINORS - 1, GFP_KERNEL);
+	if (id < 0) {
+		kfree(gdev);
+		return NULL;
+	}
+
+	gdev->id = id;
+
+	dev = &gdev->dev;
+	device_initialize(dev);
+	dev->devt = gnss_first + id;
+	dev->class = gnss_class;
+	dev->parent = parent;
+	dev->release = gnss_device_release;
+	dev_set_drvdata(dev, gdev);
+	dev_set_name(dev, "gnss%d", id);
+
+	init_rwsem(&gdev->rwsem);
+	mutex_init(&gdev->read_mutex);
+	mutex_init(&gdev->write_mutex);
+	init_waitqueue_head(&gdev->read_queue);
+
+	ret = kfifo_alloc(&gdev->read_fifo, GNSS_READ_FIFO_SIZE, GFP_KERNEL);
+	if (ret)
+		goto err_put_device;
+
+	gdev->write_buf = kzalloc(GNSS_WRITE_BUF_SIZE, GFP_KERNEL);
+	if (!gdev->write_buf)
+		goto err_put_device;
+
+	cdev_init(&gdev->cdev, &gnss_fops);
+	gdev->cdev.owner = THIS_MODULE;
+
+	return gdev;
+
+err_put_device:
+	put_device(dev);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(gnss_allocate_device);
+
+void gnss_put_device(struct gnss_device *gdev)
+{
+	put_device(&gdev->dev);
+}
+EXPORT_SYMBOL_GPL(gnss_put_device);
+
+int gnss_register_device(struct gnss_device *gdev)
+{
+	int ret;
+
+	/* Set a flag which can be accessed without holding the rwsem. */
+	if (gdev->ops->write_raw != NULL)
+		gdev->flags |= GNSS_FLAG_HAS_WRITE_RAW;
+
+	ret = cdev_device_add(&gdev->cdev, &gdev->dev);
+	if (ret) {
+		dev_err(&gdev->dev, "failed to add device: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(gnss_register_device);
+
+void gnss_deregister_device(struct gnss_device *gdev)
+{
+	down_write(&gdev->rwsem);
+	gdev->disconnected = true;
+	if (gdev->count) {
+		wake_up_interruptible(&gdev->read_queue);
+		gdev->ops->close(gdev);
+	}
+	up_write(&gdev->rwsem);
+
+	cdev_device_del(&gdev->cdev, &gdev->dev);
+}
+EXPORT_SYMBOL_GPL(gnss_deregister_device);
+
+/*
+ * Caller guarantees serialisation.
+ *
+ * Must not be called for a closed device.
+ */
+int gnss_insert_raw(struct gnss_device *gdev, const unsigned char *buf,
+				size_t count)
+{
+	int ret;
+
+	ret = kfifo_in(&gdev->read_fifo, buf, count);
+
+	wake_up_interruptible(&gdev->read_queue);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gnss_insert_raw);
+
+static const char * const gnss_type_names[GNSS_TYPE_COUNT] = {
+	[GNSS_TYPE_NMEA]	= "NMEA",
+	[GNSS_TYPE_SIRF]	= "SiRF",
+	[GNSS_TYPE_UBX]		= "UBX",
+	[GNSS_TYPE_MTK]		= "MTK",
+};
+
+static const char *gnss_type_name(const struct gnss_device *gdev)
+{
+	const char *name = NULL;
+
+	if (gdev->type < GNSS_TYPE_COUNT)
+		name = gnss_type_names[gdev->type];
+
+	if (!name)
+		dev_WARN(&gdev->dev, "type name not defined\n");
+
+	return name;
+}
+
+static ssize_t type_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct gnss_device *gdev = to_gnss_device(dev);
+
+	return sprintf(buf, "%s\n", gnss_type_name(gdev));
+}
+static DEVICE_ATTR_RO(type);
+
+static struct attribute *gnss_attrs[] = {
+	&dev_attr_type.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(gnss);
+
+static int gnss_uevent(const struct device *dev, struct kobj_uevent_env *env)
+{
+	const struct gnss_device *gdev = to_gnss_device(dev);
+	int ret;
+
+	ret = add_uevent_var(env, "GNSS_TYPE=%s", gnss_type_name(gdev));
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int __init gnss_module_init(void)
+{
+	int ret;
+
+	ret = alloc_chrdev_region(&gnss_first, 0, GNSS_MINORS, "gnss");
+	if (ret < 0) {
+		pr_err("failed to allocate device numbers: %d\n", ret);
+		return ret;
+	}
+
+	gnss_class = class_create("gnss");
+	if (IS_ERR(gnss_class)) {
+		ret = PTR_ERR(gnss_class);
+		pr_err("failed to create class: %d\n", ret);
+		goto err_unregister_chrdev;
+	}
+
+	gnss_class->dev_groups = gnss_groups;
+	gnss_class->dev_uevent = gnss_uevent;
+
+	pr_info("GNSS driver registered with major %d\n", MAJOR(gnss_first));
+
+	return 0;
+
+err_unregister_chrdev:
+	unregister_chrdev_region(gnss_first, GNSS_MINORS);
+
+	return ret;
+}
+module_init(gnss_module_init);
+
+static void __exit gnss_module_exit(void)
+{
+	class_destroy(gnss_class);
+	unregister_chrdev_region(gnss_first, GNSS_MINORS);
+	ida_destroy(&gnss_minors);
+}
+module_exit(gnss_module_exit);
+
+MODULE_AUTHOR("Johan Hovold <johan@kernel.org>");
+MODULE_DESCRIPTION("GNSS receiver core");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/gnss/mtk.c b/drivers/gnss/mtk.c
new file mode 100644
index 000000000..c62b1211f
--- /dev/null
+++ b/drivers/gnss/mtk.c
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Mediatek GNSS receiver driver
+ *
+ * Copyright (C) 2018 Johan Hovold <johan@kernel.org>
+ */
+
+#include <linux/errno.h>
+#include <linux/gnss.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regulator/consumer.h>
+#include <linux/serdev.h>
+
+#include "serial.h"
+
+struct mtk_data {
+	struct regulator *vbackup;
+	struct regulator *vcc;
+};
+
+static int mtk_set_active(struct gnss_serial *gserial)
+{
+	struct mtk_data *data = gnss_serial_get_drvdata(gserial);
+	int ret;
+
+	ret = regulator_enable(data->vcc);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int mtk_set_standby(struct gnss_serial *gserial)
+{
+	struct mtk_data *data = gnss_serial_get_drvdata(gserial);
+	int ret;
+
+	ret = regulator_disable(data->vcc);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int mtk_set_power(struct gnss_serial *gserial,
+			 enum gnss_serial_pm_state state)
+{
+	switch (state) {
+	case GNSS_SERIAL_ACTIVE:
+		return mtk_set_active(gserial);
+	case GNSS_SERIAL_OFF:
+	case GNSS_SERIAL_STANDBY:
+		return mtk_set_standby(gserial);
+	}
+
+	return -EINVAL;
+}
+
+static const struct gnss_serial_ops mtk_gserial_ops = {
+	.set_power = mtk_set_power,
+};
+
+static int mtk_probe(struct serdev_device *serdev)
+{
+	struct gnss_serial *gserial;
+	struct mtk_data *data;
+	int ret;
+
+	gserial = gnss_serial_allocate(serdev, sizeof(*data));
+	if (IS_ERR(gserial)) {
+		ret = PTR_ERR(gserial);
+		return ret;
+	}
+
+	gserial->ops = &mtk_gserial_ops;
+
+	gserial->gdev->type = GNSS_TYPE_MTK;
+
+	data = gnss_serial_get_drvdata(gserial);
+
+	data->vcc = devm_regulator_get(&serdev->dev, "vcc");
+	if (IS_ERR(data->vcc)) {
+		ret = PTR_ERR(data->vcc);
+		goto err_free_gserial;
+	}
+
+	data->vbackup = devm_regulator_get_optional(&serdev->dev, "vbackup");
+	if (IS_ERR(data->vbackup)) {
+		ret = PTR_ERR(data->vbackup);
+		if (ret == -ENODEV)
+			data->vbackup = NULL;
+		else
+			goto err_free_gserial;
+	}
+
+	if (data->vbackup) {
+		ret = regulator_enable(data->vbackup);
+		if (ret)
+			goto err_free_gserial;
+	}
+
+	ret = gnss_serial_register(gserial);
+	if (ret)
+		goto err_disable_vbackup;
+
+	return 0;
+
+err_disable_vbackup:
+	if (data->vbackup)
+		regulator_disable(data->vbackup);
+err_free_gserial:
+	gnss_serial_free(gserial);
+
+	return ret;
+}
+
+static void mtk_remove(struct serdev_device *serdev)
+{
+	struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
+	struct mtk_data *data = gnss_serial_get_drvdata(gserial);
+
+	gnss_serial_deregister(gserial);
+	if (data->vbackup)
+		regulator_disable(data->vbackup);
+	gnss_serial_free(gserial);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id mtk_of_match[] = {
+	{ .compatible = "globaltop,pa6h" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, mtk_of_match);
+#endif
+
+static struct serdev_device_driver mtk_driver = {
+	.driver	= {
+		.name		= "gnss-mtk",
+		.of_match_table	= of_match_ptr(mtk_of_match),
+		.pm		= &gnss_serial_pm_ops,
+	},
+	.probe	= mtk_probe,
+	.remove	= mtk_remove,
+};
+module_serdev_device_driver(mtk_driver);
+
+MODULE_AUTHOR("Loys Ollivier <lollivier@baylibre.com>");
+MODULE_DESCRIPTION("Mediatek GNSS receiver driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/gnss/serial.c b/drivers/gnss/serial.c
new file mode 100644
index 000000000..0e43bf629
--- /dev/null
+++ b/drivers/gnss/serial.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic serial GNSS receiver driver
+ *
+ * Copyright (C) 2018 Johan Hovold <johan@kernel.org>
+ */
+
+#include <linux/errno.h>
+#include <linux/gnss.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+#include <linux/sched.h>
+#include <linux/serdev.h>
+#include <linux/slab.h>
+
+#include "serial.h"
+
+static int gnss_serial_open(struct gnss_device *gdev)
+{
+	struct gnss_serial *gserial = gnss_get_drvdata(gdev);
+	struct serdev_device *serdev = gserial->serdev;
+	int ret;
+
+	ret = serdev_device_open(serdev);
+	if (ret)
+		return ret;
+
+	serdev_device_set_baudrate(serdev, gserial->speed);
+	serdev_device_set_flow_control(serdev, false);
+
+	ret = pm_runtime_get_sync(&serdev->dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(&serdev->dev);
+		goto err_close;
+	}
+
+	return 0;
+
+err_close:
+	serdev_device_close(serdev);
+
+	return ret;
+}
+
+static void gnss_serial_close(struct gnss_device *gdev)
+{
+	struct gnss_serial *gserial = gnss_get_drvdata(gdev);
+	struct serdev_device *serdev = gserial->serdev;
+
+	serdev_device_close(serdev);
+
+	pm_runtime_put(&serdev->dev);
+}
+
+static int gnss_serial_write_raw(struct gnss_device *gdev,
+		const unsigned char *buf, size_t count)
+{
+	struct gnss_serial *gserial = gnss_get_drvdata(gdev);
+	struct serdev_device *serdev = gserial->serdev;
+	int ret;
+
+	/* write is only buffered synchronously */
+	ret = serdev_device_write(serdev, buf, count, MAX_SCHEDULE_TIMEOUT);
+	if (ret < 0 || ret < count)
+		return ret;
+
+	/* FIXME: determine if interrupted? */
+	serdev_device_wait_until_sent(serdev, 0);
+
+	return count;
+}
+
+static const struct gnss_operations gnss_serial_gnss_ops = {
+	.open		= gnss_serial_open,
+	.close		= gnss_serial_close,
+	.write_raw	= gnss_serial_write_raw,
+};
+
+static size_t gnss_serial_receive_buf(struct serdev_device *serdev,
+				       const u8 *buf, size_t count)
+{
+	struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
+	struct gnss_device *gdev = gserial->gdev;
+
+	return gnss_insert_raw(gdev, buf, count);
+}
+
+static const struct serdev_device_ops gnss_serial_serdev_ops = {
+	.receive_buf	= gnss_serial_receive_buf,
+	.write_wakeup	= serdev_device_write_wakeup,
+};
+
+static int gnss_serial_set_power(struct gnss_serial *gserial,
+					enum gnss_serial_pm_state state)
+{
+	if (!gserial->ops || !gserial->ops->set_power)
+		return 0;
+
+	return gserial->ops->set_power(gserial, state);
+}
+
+/*
+ * FIXME: need to provide subdriver defaults or separate dt parsing from
+ * allocation.
+ */
+static int gnss_serial_parse_dt(struct serdev_device *serdev)
+{
+	struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
+	struct device_node *node = serdev->dev.of_node;
+	u32 speed = 4800;
+
+	of_property_read_u32(node, "current-speed", &speed);
+
+	gserial->speed = speed;
+
+	return 0;
+}
+
+struct gnss_serial *gnss_serial_allocate(struct serdev_device *serdev,
+						size_t data_size)
+{
+	struct gnss_serial *gserial;
+	struct gnss_device *gdev;
+	int ret;
+
+	gserial = kzalloc(sizeof(*gserial) + data_size, GFP_KERNEL);
+	if (!gserial)
+		return ERR_PTR(-ENOMEM);
+
+	gdev = gnss_allocate_device(&serdev->dev);
+	if (!gdev) {
+		ret = -ENOMEM;
+		goto err_free_gserial;
+	}
+
+	gdev->ops = &gnss_serial_gnss_ops;
+	gnss_set_drvdata(gdev, gserial);
+
+	gserial->serdev = serdev;
+	gserial->gdev = gdev;
+
+	serdev_device_set_drvdata(serdev, gserial);
+	serdev_device_set_client_ops(serdev, &gnss_serial_serdev_ops);
+
+	ret = gnss_serial_parse_dt(serdev);
+	if (ret)
+		goto err_put_device;
+
+	return gserial;
+
+err_put_device:
+	gnss_put_device(gserial->gdev);
+err_free_gserial:
+	kfree(gserial);
+
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(gnss_serial_allocate);
+
+void gnss_serial_free(struct gnss_serial *gserial)
+{
+	gnss_put_device(gserial->gdev);
+	kfree(gserial);
+}
+EXPORT_SYMBOL_GPL(gnss_serial_free);
+
+int gnss_serial_register(struct gnss_serial *gserial)
+{
+	struct serdev_device *serdev = gserial->serdev;
+	int ret;
+
+	if (IS_ENABLED(CONFIG_PM)) {
+		pm_runtime_enable(&serdev->dev);
+	} else {
+		ret = gnss_serial_set_power(gserial, GNSS_SERIAL_ACTIVE);
+		if (ret < 0)
+			return ret;
+	}
+
+	ret = gnss_register_device(gserial->gdev);
+	if (ret)
+		goto err_disable_rpm;
+
+	return 0;
+
+err_disable_rpm:
+	if (IS_ENABLED(CONFIG_PM))
+		pm_runtime_disable(&serdev->dev);
+	else
+		gnss_serial_set_power(gserial, GNSS_SERIAL_OFF);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gnss_serial_register);
+
+void gnss_serial_deregister(struct gnss_serial *gserial)
+{
+	struct serdev_device *serdev = gserial->serdev;
+
+	gnss_deregister_device(gserial->gdev);
+
+	if (IS_ENABLED(CONFIG_PM))
+		pm_runtime_disable(&serdev->dev);
+	else
+		gnss_serial_set_power(gserial, GNSS_SERIAL_OFF);
+}
+EXPORT_SYMBOL_GPL(gnss_serial_deregister);
+
+#ifdef CONFIG_PM
+static int gnss_serial_runtime_suspend(struct device *dev)
+{
+	struct gnss_serial *gserial = dev_get_drvdata(dev);
+
+	return gnss_serial_set_power(gserial, GNSS_SERIAL_STANDBY);
+}
+
+static int gnss_serial_runtime_resume(struct device *dev)
+{
+	struct gnss_serial *gserial = dev_get_drvdata(dev);
+
+	return gnss_serial_set_power(gserial, GNSS_SERIAL_ACTIVE);
+}
+#endif /* CONFIG_PM */
+
+static int gnss_serial_prepare(struct device *dev)
+{
+	if (pm_runtime_suspended(dev))
+		return 1;
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int gnss_serial_suspend(struct device *dev)
+{
+	struct gnss_serial *gserial = dev_get_drvdata(dev);
+	int ret = 0;
+
+	/*
+	 * FIXME: serdev currently lacks support for managing the underlying
+	 * device's wakeup settings. A workaround would be to close the serdev
+	 * device here if it is open.
+	 */
+
+	if (!pm_runtime_suspended(dev))
+		ret = gnss_serial_set_power(gserial, GNSS_SERIAL_STANDBY);
+
+	return ret;
+}
+
+static int gnss_serial_resume(struct device *dev)
+{
+	struct gnss_serial *gserial = dev_get_drvdata(dev);
+	int ret = 0;
+
+	if (!pm_runtime_suspended(dev))
+		ret = gnss_serial_set_power(gserial, GNSS_SERIAL_ACTIVE);
+
+	return ret;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+const struct dev_pm_ops gnss_serial_pm_ops = {
+	.prepare	= gnss_serial_prepare,
+	SET_SYSTEM_SLEEP_PM_OPS(gnss_serial_suspend, gnss_serial_resume)
+	SET_RUNTIME_PM_OPS(gnss_serial_runtime_suspend, gnss_serial_runtime_resume, NULL)
+};
+EXPORT_SYMBOL_GPL(gnss_serial_pm_ops);
+
+MODULE_AUTHOR("Johan Hovold <johan@kernel.org>");
+MODULE_DESCRIPTION("Generic serial GNSS receiver driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/gnss/serial.h b/drivers/gnss/serial.h
new file mode 100644
index 000000000..621953f78
--- /dev/null
+++ b/drivers/gnss/serial.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Generic serial GNSS receiver driver
+ *
+ * Copyright (C) 2018 Johan Hovold <johan@kernel.org>
+ */
+
+#ifndef _LINUX_GNSS_SERIAL_H
+#define _LINUX_GNSS_SERIAL_H
+
+#include <asm/termbits.h>
+#include <linux/pm.h>
+
+struct gnss_serial {
+	struct serdev_device *serdev;
+	struct gnss_device *gdev;
+	speed_t	speed;
+	const struct gnss_serial_ops *ops;
+	unsigned long drvdata[];
+};
+
+enum gnss_serial_pm_state {
+	GNSS_SERIAL_OFF,
+	GNSS_SERIAL_ACTIVE,
+	GNSS_SERIAL_STANDBY,
+};
+
+struct gnss_serial_ops {
+	int (*set_power)(struct gnss_serial *gserial,
+				enum gnss_serial_pm_state state);
+};
+
+extern const struct dev_pm_ops gnss_serial_pm_ops;
+
+struct gnss_serial *gnss_serial_allocate(struct serdev_device *gserial,
+						size_t data_size);
+void gnss_serial_free(struct gnss_serial *gserial);
+
+int gnss_serial_register(struct gnss_serial *gserial);
+void gnss_serial_deregister(struct gnss_serial *gserial);
+
+static inline void *gnss_serial_get_drvdata(struct gnss_serial *gserial)
+{
+	return gserial->drvdata;
+}
+
+#endif /* _LINUX_GNSS_SERIAL_H */
diff --git a/drivers/gnss/sirf.c b/drivers/gnss/sirf.c
new file mode 100644
index 000000000..79375d14b
--- /dev/null
+++ b/drivers/gnss/sirf.c
@@ -0,0 +1,581 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * SiRFstar GNSS receiver driver
+ *
+ * Copyright (C) 2018 Johan Hovold <johan@kernel.org>
+ */
+
+#include <linux/errno.h>
+#include <linux/gnss.h>
+#include <linux/gpio/consumer.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.h>
+#include <linux/sched.h>
+#include <linux/serdev.h>
+#include <linux/slab.h>
+#include <linux/wait.h>
+
+#define SIRF_BOOT_DELAY			500
+#define SIRF_ON_OFF_PULSE_TIME		100
+#define SIRF_ACTIVATE_TIMEOUT		200
+#define SIRF_HIBERNATE_TIMEOUT		200
+/*
+ * If no data arrives for this time, we assume that the chip is off.
+ * REVISIT: The report cycle is configurable and can be several minutes long,
+ * so this will only work reliably if the report cycle is set to a reasonable
+ * low value. Also power saving settings (like send data only on movement)
+ * might things work even worse.
+ * Workaround might be to parse shutdown or bootup messages.
+ */
+#define SIRF_REPORT_CYCLE	2000
+
+struct sirf_data {
+	struct gnss_device *gdev;
+	struct serdev_device *serdev;
+	speed_t	speed;
+	struct regulator *vcc;
+	struct regulator *lna;
+	struct gpio_desc *on_off;
+	struct gpio_desc *wakeup;
+	int irq;
+	bool active;
+
+	struct mutex gdev_mutex;
+	bool open;
+
+	struct mutex serdev_mutex;
+	int serdev_count;
+
+	wait_queue_head_t power_wait;
+};
+
+static int sirf_serdev_open(struct sirf_data *data)
+{
+	int ret = 0;
+
+	mutex_lock(&data->serdev_mutex);
+	if (++data->serdev_count == 1) {
+		ret = serdev_device_open(data->serdev);
+		if (ret) {
+			data->serdev_count--;
+			goto out_unlock;
+		}
+
+		serdev_device_set_baudrate(data->serdev, data->speed);
+		serdev_device_set_flow_control(data->serdev, false);
+	}
+
+out_unlock:
+	mutex_unlock(&data->serdev_mutex);
+
+	return ret;
+}
+
+static void sirf_serdev_close(struct sirf_data *data)
+{
+	mutex_lock(&data->serdev_mutex);
+	if (--data->serdev_count == 0)
+		serdev_device_close(data->serdev);
+	mutex_unlock(&data->serdev_mutex);
+}
+
+static int sirf_open(struct gnss_device *gdev)
+{
+	struct sirf_data *data = gnss_get_drvdata(gdev);
+	struct serdev_device *serdev = data->serdev;
+	int ret;
+
+	mutex_lock(&data->gdev_mutex);
+	data->open = true;
+	mutex_unlock(&data->gdev_mutex);
+
+	ret = sirf_serdev_open(data);
+	if (ret) {
+		mutex_lock(&data->gdev_mutex);
+		data->open = false;
+		mutex_unlock(&data->gdev_mutex);
+		return ret;
+	}
+
+	ret = pm_runtime_get_sync(&serdev->dev);
+	if (ret < 0) {
+		dev_err(&gdev->dev, "failed to runtime resume: %d\n", ret);
+		pm_runtime_put_noidle(&serdev->dev);
+		goto err_close;
+	}
+
+	return 0;
+
+err_close:
+	sirf_serdev_close(data);
+
+	mutex_lock(&data->gdev_mutex);
+	data->open = false;
+	mutex_unlock(&data->gdev_mutex);
+
+	return ret;
+}
+
+static void sirf_close(struct gnss_device *gdev)
+{
+	struct sirf_data *data = gnss_get_drvdata(gdev);
+	struct serdev_device *serdev = data->serdev;
+
+	sirf_serdev_close(data);
+
+	pm_runtime_put(&serdev->dev);
+
+	mutex_lock(&data->gdev_mutex);
+	data->open = false;
+	mutex_unlock(&data->gdev_mutex);
+}
+
+static int sirf_write_raw(struct gnss_device *gdev, const unsigned char *buf,
+				size_t count)
+{
+	struct sirf_data *data = gnss_get_drvdata(gdev);
+	struct serdev_device *serdev = data->serdev;
+	int ret;
+
+	/* write is only buffered synchronously */
+	ret = serdev_device_write(serdev, buf, count, MAX_SCHEDULE_TIMEOUT);
+	if (ret < 0 || ret < count)
+		return ret;
+
+	/* FIXME: determine if interrupted? */
+	serdev_device_wait_until_sent(serdev, 0);
+
+	return count;
+}
+
+static const struct gnss_operations sirf_gnss_ops = {
+	.open		= sirf_open,
+	.close		= sirf_close,
+	.write_raw	= sirf_write_raw,
+};
+
+static size_t sirf_receive_buf(struct serdev_device *serdev,
+				const u8 *buf, size_t count)
+{
+	struct sirf_data *data = serdev_device_get_drvdata(serdev);
+	struct gnss_device *gdev = data->gdev;
+	int ret = 0;
+
+	if (!data->wakeup && !data->active) {
+		data->active = true;
+		wake_up_interruptible(&data->power_wait);
+	}
+
+	mutex_lock(&data->gdev_mutex);
+	if (data->open)
+		ret = gnss_insert_raw(gdev, buf, count);
+	mutex_unlock(&data->gdev_mutex);
+
+	return ret;
+}
+
+static const struct serdev_device_ops sirf_serdev_ops = {
+	.receive_buf	= sirf_receive_buf,
+	.write_wakeup	= serdev_device_write_wakeup,
+};
+
+static irqreturn_t sirf_wakeup_handler(int irq, void *dev_id)
+{
+	struct sirf_data *data = dev_id;
+	struct device *dev = &data->serdev->dev;
+	int ret;
+
+	ret = gpiod_get_value_cansleep(data->wakeup);
+	dev_dbg(dev, "%s - wakeup = %d\n", __func__, ret);
+	if (ret < 0)
+		goto out;
+
+	data->active = ret;
+	wake_up_interruptible(&data->power_wait);
+out:
+	return IRQ_HANDLED;
+}
+
+static int sirf_wait_for_power_state_nowakeup(struct sirf_data *data,
+						bool active,
+						unsigned long timeout)
+{
+	int ret;
+
+	/* Wait for state change (including any shutdown messages). */
+	msleep(timeout);
+
+	/* Wait for data reception or timeout. */
+	data->active = false;
+	ret = wait_event_interruptible_timeout(data->power_wait,
+			data->active, msecs_to_jiffies(SIRF_REPORT_CYCLE));
+	if (ret < 0)
+		return ret;
+
+	if (ret > 0 && !active)
+		return -ETIMEDOUT;
+
+	if (ret == 0 && active)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static int sirf_wait_for_power_state(struct sirf_data *data, bool active,
+					unsigned long timeout)
+{
+	int ret;
+
+	if (!data->wakeup)
+		return sirf_wait_for_power_state_nowakeup(data, active, timeout);
+
+	ret = wait_event_interruptible_timeout(data->power_wait,
+			data->active == active, msecs_to_jiffies(timeout));
+	if (ret < 0)
+		return ret;
+
+	if (ret == 0) {
+		dev_warn(&data->serdev->dev, "timeout waiting for active state = %d\n",
+				active);
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static void sirf_pulse_on_off(struct sirf_data *data)
+{
+	gpiod_set_value_cansleep(data->on_off, 1);
+	msleep(SIRF_ON_OFF_PULSE_TIME);
+	gpiod_set_value_cansleep(data->on_off, 0);
+}
+
+static int sirf_set_active(struct sirf_data *data, bool active)
+{
+	unsigned long timeout;
+	int retries = 3;
+	int ret;
+
+	if (active)
+		timeout = SIRF_ACTIVATE_TIMEOUT;
+	else
+		timeout = SIRF_HIBERNATE_TIMEOUT;
+
+	if (!data->wakeup) {
+		ret = sirf_serdev_open(data);
+		if (ret)
+			return ret;
+	}
+
+	do {
+		sirf_pulse_on_off(data);
+		ret = sirf_wait_for_power_state(data, active, timeout);
+	} while (ret == -ETIMEDOUT && retries--);
+
+	if (!data->wakeup)
+		sirf_serdev_close(data);
+
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int sirf_runtime_suspend(struct device *dev)
+{
+	struct sirf_data *data = dev_get_drvdata(dev);
+	int ret2;
+	int ret;
+
+	if (data->on_off)
+		ret = sirf_set_active(data, false);
+	else
+		ret = regulator_disable(data->vcc);
+
+	if (ret)
+		return ret;
+
+	ret = regulator_disable(data->lna);
+	if (ret)
+		goto err_reenable;
+
+	return 0;
+
+err_reenable:
+	if (data->on_off)
+		ret2 = sirf_set_active(data, true);
+	else
+		ret2 = regulator_enable(data->vcc);
+
+	if (ret2)
+		dev_err(dev,
+			"failed to reenable power on failed suspend: %d\n",
+			ret2);
+
+	return ret;
+}
+
+static int sirf_runtime_resume(struct device *dev)
+{
+	struct sirf_data *data = dev_get_drvdata(dev);
+	int ret;
+
+	ret = regulator_enable(data->lna);
+	if (ret)
+		return ret;
+
+	if (data->on_off)
+		ret = sirf_set_active(data, true);
+	else
+		ret = regulator_enable(data->vcc);
+
+	if (ret)
+		goto err_disable_lna;
+
+	return 0;
+
+err_disable_lna:
+	regulator_disable(data->lna);
+
+	return ret;
+}
+
+static int __maybe_unused sirf_suspend(struct device *dev)
+{
+	struct sirf_data *data = dev_get_drvdata(dev);
+	int ret = 0;
+
+	if (!pm_runtime_suspended(dev))
+		ret = sirf_runtime_suspend(dev);
+
+	if (data->wakeup)
+		disable_irq(data->irq);
+
+	return ret;
+}
+
+static int __maybe_unused sirf_resume(struct device *dev)
+{
+	struct sirf_data *data = dev_get_drvdata(dev);
+	int ret = 0;
+
+	if (data->wakeup)
+		enable_irq(data->irq);
+
+	if (!pm_runtime_suspended(dev))
+		ret = sirf_runtime_resume(dev);
+
+	return ret;
+}
+
+static const struct dev_pm_ops sirf_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(sirf_suspend, sirf_resume)
+	SET_RUNTIME_PM_OPS(sirf_runtime_suspend, sirf_runtime_resume, NULL)
+};
+
+static int sirf_parse_dt(struct serdev_device *serdev)
+{
+	struct sirf_data *data = serdev_device_get_drvdata(serdev);
+	struct device_node *node = serdev->dev.of_node;
+	u32 speed = 9600;
+
+	of_property_read_u32(node, "current-speed", &speed);
+
+	data->speed = speed;
+
+	return 0;
+}
+
+static int sirf_probe(struct serdev_device *serdev)
+{
+	struct device *dev = &serdev->dev;
+	struct gnss_device *gdev;
+	struct sirf_data *data;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	gdev = gnss_allocate_device(dev);
+	if (!gdev)
+		return -ENOMEM;
+
+	gdev->type = GNSS_TYPE_SIRF;
+	gdev->ops = &sirf_gnss_ops;
+	gnss_set_drvdata(gdev, data);
+
+	data->serdev = serdev;
+	data->gdev = gdev;
+
+	mutex_init(&data->gdev_mutex);
+	mutex_init(&data->serdev_mutex);
+	init_waitqueue_head(&data->power_wait);
+
+	serdev_device_set_drvdata(serdev, data);
+	serdev_device_set_client_ops(serdev, &sirf_serdev_ops);
+
+	ret = sirf_parse_dt(serdev);
+	if (ret)
+		goto err_put_device;
+
+	data->vcc = devm_regulator_get(dev, "vcc");
+	if (IS_ERR(data->vcc)) {
+		ret = PTR_ERR(data->vcc);
+		goto err_put_device;
+	}
+
+	data->lna = devm_regulator_get(dev, "lna");
+	if (IS_ERR(data->lna)) {
+		ret = PTR_ERR(data->lna);
+		goto err_put_device;
+	}
+
+	data->on_off = devm_gpiod_get_optional(dev, "sirf,onoff",
+			GPIOD_OUT_LOW);
+	if (IS_ERR(data->on_off)) {
+		ret = PTR_ERR(data->on_off);
+		goto err_put_device;
+	}
+
+	if (data->on_off) {
+		data->wakeup = devm_gpiod_get_optional(dev, "sirf,wakeup",
+				GPIOD_IN);
+		if (IS_ERR(data->wakeup)) {
+			ret = PTR_ERR(data->wakeup);
+			goto err_put_device;
+		}
+
+		ret = regulator_enable(data->vcc);
+		if (ret)
+			goto err_put_device;
+
+		/* Wait for chip to boot into hibernate mode. */
+		msleep(SIRF_BOOT_DELAY);
+	}
+
+	if (data->wakeup) {
+		ret = gpiod_get_value_cansleep(data->wakeup);
+		if (ret < 0)
+			goto err_disable_vcc;
+		data->active = ret;
+
+		ret = gpiod_to_irq(data->wakeup);
+		if (ret < 0)
+			goto err_disable_vcc;
+		data->irq = ret;
+
+		ret = request_threaded_irq(data->irq, NULL, sirf_wakeup_handler,
+				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+				"wakeup", data);
+		if (ret)
+			goto err_disable_vcc;
+	}
+
+	if (data->on_off) {
+		if (!data->wakeup) {
+			data->active = false;
+
+			ret = sirf_serdev_open(data);
+			if (ret)
+				goto err_disable_vcc;
+
+			msleep(SIRF_REPORT_CYCLE);
+			sirf_serdev_close(data);
+		}
+
+		/* Force hibernate mode if already active. */
+		if (data->active) {
+			ret = sirf_set_active(data, false);
+			if (ret) {
+				dev_err(dev, "failed to set hibernate mode: %d\n",
+						ret);
+				goto err_free_irq;
+			}
+		}
+	}
+
+	if (IS_ENABLED(CONFIG_PM)) {
+		pm_runtime_set_suspended(dev);	/* clear runtime_error flag */
+		pm_runtime_enable(dev);
+	} else {
+		ret = sirf_runtime_resume(dev);
+		if (ret < 0)
+			goto err_free_irq;
+	}
+
+	ret = gnss_register_device(gdev);
+	if (ret)
+		goto err_disable_rpm;
+
+	return 0;
+
+err_disable_rpm:
+	if (IS_ENABLED(CONFIG_PM))
+		pm_runtime_disable(dev);
+	else
+		sirf_runtime_suspend(dev);
+err_free_irq:
+	if (data->wakeup)
+		free_irq(data->irq, data);
+err_disable_vcc:
+	if (data->on_off)
+		regulator_disable(data->vcc);
+err_put_device:
+	gnss_put_device(data->gdev);
+
+	return ret;
+}
+
+static void sirf_remove(struct serdev_device *serdev)
+{
+	struct sirf_data *data = serdev_device_get_drvdata(serdev);
+
+	gnss_deregister_device(data->gdev);
+
+	if (IS_ENABLED(CONFIG_PM))
+		pm_runtime_disable(&serdev->dev);
+	else
+		sirf_runtime_suspend(&serdev->dev);
+
+	if (data->wakeup)
+		free_irq(data->irq, data);
+
+	if (data->on_off)
+		regulator_disable(data->vcc);
+
+	gnss_put_device(data->gdev);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id sirf_of_match[] = {
+	{ .compatible = "fastrax,uc430" },
+	{ .compatible = "linx,r4" },
+	{ .compatible = "wi2wi,w2sg0004" },
+	{ .compatible = "wi2wi,w2sg0008i" },
+	{ .compatible = "wi2wi,w2sg0084i" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, sirf_of_match);
+#endif
+
+static struct serdev_device_driver sirf_driver = {
+	.driver	= {
+		.name		= "gnss-sirf",
+		.of_match_table	= of_match_ptr(sirf_of_match),
+		.pm		= &sirf_pm_ops,
+	},
+	.probe	= sirf_probe,
+	.remove	= sirf_remove,
+};
+module_serdev_device_driver(sirf_driver);
+
+MODULE_AUTHOR("Johan Hovold <johan@kernel.org>");
+MODULE_DESCRIPTION("SiRFstar GNSS receiver driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/gnss/ubx.c b/drivers/gnss/ubx.c
new file mode 100644
index 000000000..23894ff75
--- /dev/null
+++ b/drivers/gnss/ubx.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * u-blox GNSS receiver driver
+ *
+ * Copyright (C) 2018 Johan Hovold <johan@kernel.org>
+ */
+
+#include <linux/errno.h>
+#include <linux/gnss.h>
+#include <linux/gpio/consumer.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regulator/consumer.h>
+#include <linux/serdev.h>
+
+#include "serial.h"
+
+struct ubx_data {
+	struct regulator *vcc;
+};
+
+static int ubx_set_active(struct gnss_serial *gserial)
+{
+	struct ubx_data *data = gnss_serial_get_drvdata(gserial);
+	int ret;
+
+	ret = regulator_enable(data->vcc);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ubx_set_standby(struct gnss_serial *gserial)
+{
+	struct ubx_data *data = gnss_serial_get_drvdata(gserial);
+	int ret;
+
+	ret = regulator_disable(data->vcc);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ubx_set_power(struct gnss_serial *gserial,
+				enum gnss_serial_pm_state state)
+{
+	switch (state) {
+	case GNSS_SERIAL_ACTIVE:
+		return ubx_set_active(gserial);
+	case GNSS_SERIAL_OFF:
+	case GNSS_SERIAL_STANDBY:
+		return ubx_set_standby(gserial);
+	}
+
+	return -EINVAL;
+}
+
+static const struct gnss_serial_ops ubx_gserial_ops = {
+	.set_power = ubx_set_power,
+};
+
+static int ubx_probe(struct serdev_device *serdev)
+{
+	struct gnss_serial *gserial;
+	struct gpio_desc *safeboot;
+	struct gpio_desc *reset;
+	struct ubx_data *data;
+	int ret;
+
+	gserial = gnss_serial_allocate(serdev, sizeof(*data));
+	if (IS_ERR(gserial)) {
+		ret = PTR_ERR(gserial);
+		return ret;
+	}
+
+	gserial->ops = &ubx_gserial_ops;
+
+	gserial->gdev->type = GNSS_TYPE_UBX;
+
+	data = gnss_serial_get_drvdata(gserial);
+
+	data->vcc = devm_regulator_get(&serdev->dev, "vcc");
+	if (IS_ERR(data->vcc)) {
+		ret = PTR_ERR(data->vcc);
+		goto err_free_gserial;
+	}
+
+	ret = devm_regulator_get_enable_optional(&serdev->dev, "v-bckp");
+	if (ret < 0 && ret != -ENODEV)
+		goto err_free_gserial;
+
+	/* Deassert safeboot */
+	safeboot = devm_gpiod_get_optional(&serdev->dev, "safeboot", GPIOD_OUT_LOW);
+	if (IS_ERR(safeboot)) {
+		ret = PTR_ERR(safeboot);
+		goto err_free_gserial;
+	}
+
+	/* Deassert reset */
+	reset = devm_gpiod_get_optional(&serdev->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(reset)) {
+		ret = PTR_ERR(reset);
+		goto err_free_gserial;
+	}
+
+	ret = gnss_serial_register(gserial);
+	if (ret)
+		goto err_free_gserial;
+
+	return 0;
+
+err_free_gserial:
+	gnss_serial_free(gserial);
+
+	return ret;
+}
+
+static void ubx_remove(struct serdev_device *serdev)
+{
+	struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
+
+	gnss_serial_deregister(gserial);
+	gnss_serial_free(gserial);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id ubx_of_match[] = {
+	{ .compatible = "u-blox,neo-6m" },
+	{ .compatible = "u-blox,neo-8" },
+	{ .compatible = "u-blox,neo-m8" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ubx_of_match);
+#endif
+
+static struct serdev_device_driver ubx_driver = {
+	.driver	= {
+		.name		= "gnss-ubx",
+		.of_match_table	= of_match_ptr(ubx_of_match),
+		.pm		= &gnss_serial_pm_ops,
+	},
+	.probe	= ubx_probe,
+	.remove	= ubx_remove,
+};
+module_serdev_device_driver(ubx_driver);
+
+MODULE_AUTHOR("Johan Hovold <johan@kernel.org>");
+MODULE_DESCRIPTION("u-blox GNSS receiver driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/gnss/usb.c b/drivers/gnss/usb.c
new file mode 100644
index 000000000..0d9dde023
--- /dev/null
+++ b/drivers/gnss/usb.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic USB GNSS receiver driver
+ *
+ * Copyright (C) 2021 Johan Hovold <johan@kernel.org>
+ */
+
+#include <linux/errno.h>
+#include <linux/gnss.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+#define GNSS_USB_READ_BUF_LEN	512
+#define GNSS_USB_WRITE_TIMEOUT	1000
+
+static const struct usb_device_id gnss_usb_id_table[] = {
+	{ USB_DEVICE(0x1199, 0xb000) },		/* Sierra Wireless XM1210 */
+	{ }
+};
+MODULE_DEVICE_TABLE(usb, gnss_usb_id_table);
+
+struct gnss_usb {
+	struct usb_device *udev;
+	struct usb_interface *intf;
+	struct gnss_device *gdev;
+	struct urb *read_urb;
+	unsigned int write_pipe;
+};
+
+static void gnss_usb_rx_complete(struct urb *urb)
+{
+	struct gnss_usb *gusb = urb->context;
+	struct gnss_device *gdev = gusb->gdev;
+	int status = urb->status;
+	int len;
+	int ret;
+
+	switch (status) {
+	case 0:
+		break;
+	case -ENOENT:
+	case -ECONNRESET:
+	case -ESHUTDOWN:
+		dev_dbg(&gdev->dev, "urb stopped: %d\n", status);
+		return;
+	case -EPIPE:
+		dev_err(&gdev->dev, "urb stopped: %d\n", status);
+		return;
+	default:
+		dev_dbg(&gdev->dev, "nonzero urb status: %d\n", status);
+		goto resubmit;
+	}
+
+	len = urb->actual_length;
+	if (len == 0)
+		goto resubmit;
+
+	ret = gnss_insert_raw(gdev, urb->transfer_buffer, len);
+	if (ret < len)
+		dev_dbg(&gdev->dev, "dropped %d bytes\n", len - ret);
+resubmit:
+	ret = usb_submit_urb(urb, GFP_ATOMIC);
+	if (ret && ret != -EPERM && ret != -ENODEV)
+		dev_err(&gdev->dev, "failed to resubmit urb: %d\n", ret);
+}
+
+static int gnss_usb_open(struct gnss_device *gdev)
+{
+	struct gnss_usb *gusb = gnss_get_drvdata(gdev);
+	int ret;
+
+	ret = usb_submit_urb(gusb->read_urb, GFP_KERNEL);
+	if (ret) {
+		if (ret != -EPERM && ret != -ENODEV)
+			dev_err(&gdev->dev, "failed to submit urb: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void gnss_usb_close(struct gnss_device *gdev)
+{
+	struct gnss_usb *gusb = gnss_get_drvdata(gdev);
+
+	usb_kill_urb(gusb->read_urb);
+}
+
+static int gnss_usb_write_raw(struct gnss_device *gdev,
+		const unsigned char *buf, size_t count)
+{
+	struct gnss_usb *gusb = gnss_get_drvdata(gdev);
+	void *tbuf;
+	int ret;
+
+	tbuf = kmemdup(buf, count, GFP_KERNEL);
+	if (!tbuf)
+		return -ENOMEM;
+
+	ret = usb_bulk_msg(gusb->udev, gusb->write_pipe, tbuf, count, NULL,
+			GNSS_USB_WRITE_TIMEOUT);
+	kfree(tbuf);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static const struct gnss_operations gnss_usb_gnss_ops = {
+	.open		= gnss_usb_open,
+	.close		= gnss_usb_close,
+	.write_raw	= gnss_usb_write_raw,
+};
+
+static int gnss_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
+{
+	struct usb_device *udev = interface_to_usbdev(intf);
+	struct usb_endpoint_descriptor *in, *out;
+	struct gnss_device *gdev;
+	struct gnss_usb *gusb;
+	struct urb *urb;
+	size_t buf_len;
+	void *buf;
+	int ret;
+
+	ret = usb_find_common_endpoints(intf->cur_altsetting, &in, &out, NULL,
+			NULL);
+	if (ret)
+		return ret;
+
+	gusb = kzalloc_obj(*gusb);
+	if (!gusb)
+		return -ENOMEM;
+
+	gdev = gnss_allocate_device(&intf->dev);
+	if (!gdev) {
+		ret = -ENOMEM;
+		goto err_free_gusb;
+	}
+
+	gdev->ops = &gnss_usb_gnss_ops;
+	gdev->type = GNSS_TYPE_NMEA;
+	gnss_set_drvdata(gdev, gusb);
+
+	urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!urb) {
+		ret = -ENOMEM;
+		goto err_put_gdev;
+	}
+
+	buf_len = max(usb_endpoint_maxp(in), GNSS_USB_READ_BUF_LEN);
+
+	buf = kzalloc(buf_len, GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto err_free_urb;
+	}
+
+	usb_fill_bulk_urb(urb, udev,
+			usb_rcvbulkpipe(udev, usb_endpoint_num(in)),
+			buf, buf_len, gnss_usb_rx_complete, gusb);
+
+	gusb->intf = intf;
+	gusb->udev = udev;
+	gusb->gdev = gdev;
+	gusb->read_urb = urb;
+	gusb->write_pipe = usb_sndbulkpipe(udev, usb_endpoint_num(out));
+
+	ret = gnss_register_device(gdev);
+	if (ret)
+		goto err_free_buf;
+
+	usb_set_intfdata(intf, gusb);
+
+	return 0;
+
+err_free_buf:
+	kfree(buf);
+err_free_urb:
+	usb_free_urb(urb);
+err_put_gdev:
+	gnss_put_device(gdev);
+err_free_gusb:
+	kfree(gusb);
+
+	return ret;
+}
+
+static void gnss_usb_disconnect(struct usb_interface *intf)
+{
+	struct gnss_usb *gusb = usb_get_intfdata(intf);
+
+	gnss_deregister_device(gusb->gdev);
+
+	kfree(gusb->read_urb->transfer_buffer);
+	usb_free_urb(gusb->read_urb);
+	gnss_put_device(gusb->gdev);
+	kfree(gusb);
+}
+
+static struct usb_driver gnss_usb_driver = {
+	.name		= "gnss-usb",
+	.probe		= gnss_usb_probe,
+	.disconnect	= gnss_usb_disconnect,
+	.id_table	= gnss_usb_id_table,
+};
+module_usb_driver(gnss_usb_driver);
+
+MODULE_AUTHOR("Johan Hovold <johan@kernel.org>");
+MODULE_DESCRIPTION("Generic USB GNSS receiver driver");
+MODULE_LICENSE("GPL v2");