diff --git a/Documentation/ABI/testing/configfs-stp-policy b/Documentation/ABI/testing/configfs-stp-policy
new file mode 100644
index 0000000..421ce68
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-stp-policy
@@ -0,0 +1,48 @@
+What:		/config/stp-policy
+Date:		June 2015
+KernelVersion:	4.3
+Description:
+		This group contains policies mandating Master/Channel allocation
+		for software sources wishing to send trace data over an STM
+		device.
+
+What:		/config/stp-policy/<device>.<policy>
+Date:		June 2015
+KernelVersion:	4.3
+Description:
+		This group is the root of a policy; its name is a concatenation
+		of an stm device name to which this policy applies and an
+		arbitrary string. If <device> part doesn't match an existing
+		stm device, mkdir will fail with ENODEV; if that device already
+		has a policy assigned to it, mkdir will fail with EBUSY.
+
+What:		/config/stp-policy/<device>.<policy>/device
+Date:		June 2015
+KernelVersion:	4.3
+Description:
+		STM device to which this policy applies, read only. Same as the
+		<device> component of its parent directory.
+
+What:		/config/stp-policy/<device>.<policy>/<node>
+Date:		June 2015
+KernelVersion:	4.3
+Description:
+		Policy node is a string identifier that software clients will
+		use to request a master/channel to be allocated and assigned to
+		them.
+
+What:		/config/stp-policy/<device>.<policy>/<node>/masters
+Date:		June 2015
+KernelVersion:	4.3
+Description:
+		Range of masters from which to allocate for users of this node.
+		Write two numbers: the first master and the last master number.
+
+What:		/config/stp-policy/<device>.<policy>/<node>/channels
+Date:		June 2015
+KernelVersion:	4.3
+Description:
+		Range of channels from which to allocate for users of this node.
+		Write two numbers: the first channel and the last channel
+		number.
+
diff --git a/Documentation/ABI/testing/sysfs-class-stm b/Documentation/ABI/testing/sysfs-class-stm
new file mode 100644
index 0000000..c9aa4f3
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-stm
@@ -0,0 +1,14 @@
+What:		/sys/class/stm/<stm>/masters
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Description:
+		Shows first and last available to software master numbers on
+		this STM device.
+
+What:		/sys/class/stm/<stm>/channels
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Description:
+		Shows the number of channels per master on this STM device.
diff --git a/Documentation/ABI/testing/sysfs-class-stm_source b/Documentation/ABI/testing/sysfs-class-stm_source
new file mode 100644
index 0000000..57b8dd3
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-stm_source
@@ -0,0 +1,11 @@
+What:		/sys/class/stm_source/<stm_source>/stm_source_link
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Description:
+		stm_source device linkage to stm device, where its tracing data
+		is directed. Reads return an existing connection or "<none>" if
+		this stm_source is not connected to any stm device yet.
+		Write an existing (registered) stm device's name here to
+		connect that device. If a device is already connected to this
+		stm_source, it will first be disconnected.
diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
index df1b25e..3785b7e 100644
--- a/Documentation/ioctl/ioctl-number.txt
+++ b/Documentation/ioctl/ioctl-number.txt
@@ -81,6 +81,9 @@
 0x22	all	scsi/sg.h
 '#'	00-3F	IEEE 1394 Subsystem	Block for the entire subsystem
 '$'	00-0F	linux/perf_counter.h, linux/perf_event.h
+'%'	00-0F	include/uapi/linux/stm.h
+					System Trace Module subsystem
+					<mailto:alexander.shishkin@linux.intel.com>
 '&'	00-07	drivers/firewire/nosy-user.h
 '1'	00-1F	<linux/timepps.h>	PPS kit from Ulrich Windl
 					<ftp://ftp.de.kernel.org/pub/linux/daemons/ntp/PPS/>
diff --git a/Documentation/trace/stm.txt b/Documentation/trace/stm.txt
new file mode 100644
index 0000000..ea035f9
--- /dev/null
+++ b/Documentation/trace/stm.txt
@@ -0,0 +1,80 @@
+System Trace Module
+===================
+
+System Trace Module (STM) is a device described in MIPI STP specs as
+STP trace stream generator. STP (System Trace Protocol) is a trace
+protocol multiplexing data from multiple trace sources, each one of
+which is assigned a unique pair of master and channel. While some of
+these masters and channels are statically allocated to certain
+hardware trace sources, others are available to software. Software
+trace sources are usually free to pick for themselves any
+master/channel combination from this pool.
+
+On the receiving end of this STP stream (the decoder side), trace
+sources can only be identified by master/channel combination, so in
+order for the decoder to be able to make sense of the trace that
+involves multiple trace sources, it needs to be able to map those
+master/channel pairs to the trace sources that it understands.
+
+For instance, it is helpful to know that syslog messages come on
+master 7 channel 15, while arbitrary user applications can use masters
+48 to 63 and channels 0 to 127.
+
+To solve this mapping problem, stm class provides a policy management
+mechanism via configfs, that allows defining rules that map string
+identifiers to ranges of masters and channels. If these rules (policy)
+are consistent with what decoder expects, it will be able to properly
+process the trace data.
+
+This policy is a tree structure containing rules (policy_node) that
+have a name (string identifier) and a range of masters and channels
+associated with it, located in "stp-policy" subsystem directory in
+configfs. The topmost directory's name (the policy) is formatted as
+the STM device name to which this policy applies and and arbitrary
+string identifier separated by a stop. From the examle above, a rule
+may look like this:
+
+$ ls /config/stp-policy/dummy_stm.my-policy/user
+channels masters
+$ cat /config/stp-policy/dummy_stm.my-policy/user/masters
+48 63
+$ cat /config/stp-policy/dummy_stm.my-policy/user/channels
+0 127
+
+which means that the master allocation pool for this rule consists of
+masters 48 through 63 and channel allocation pool has channels 0
+through 127 in it. Now, any producer (trace source) identifying itself
+with "user" identification string will be allocated a master and
+channel from within these ranges.
+
+These rules can be nested, for example, one can define a rule "dummy"
+under "user" directory from the example above and this new rule will
+be used for trace sources with the id string of "user/dummy".
+
+Trace sources have to open the stm class device's node and write their
+trace data into its file descriptor. In order to identify themselves
+to the policy, they need to do a STP_POLICY_ID_SET ioctl on this file
+descriptor providing their id string. Otherwise, they will be
+automatically allocated a master/channel pair upon first write to this
+file descriptor according to the "default" rule of the policy, if such
+exists.
+
+Some STM devices may allow direct mapping of the channel mmio regions
+to userspace for zero-copy writing. One mappable page (in terms of
+mmu) will usually contain multiple channels' mmios, so the user will
+need to allocate that many channels to themselves (via the
+aforementioned ioctl() call) to be able to do this. That is, if your
+stm device's channel mmio region is 64 bytes and hardware page size is
+4096 bytes, after a successful STP_POLICY_ID_SET ioctl() call with
+width==64, you should be able to mmap() one page on this file
+descriptor and obtain direct access to an mmio region for 64 channels.
+
+For kernel-based trace sources, there is "stm_source" device
+class. Devices of this class can be connected and disconnected to/from
+stm devices at runtime via a sysfs attribute.
+
+Examples of STM devices are Intel(R) Trace Hub [1] and Coresight STM
+[2].
+
+[1] https://software.intel.com/sites/default/files/managed/d3/3c/intel-th-developer-manual.pdf
+[2] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0444b/index.html
diff --git a/drivers/Kconfig b/drivers/Kconfig
index 46b4a8e..b6e1cea6 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -188,4 +188,6 @@
 
 source "drivers/nvmem/Kconfig"
 
+source "drivers/hwtracing/stm/Kconfig"
+
 endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index b250b36..e71b5e2 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -165,5 +165,6 @@
 obj-$(CONFIG_RAS)		+= ras/
 obj-$(CONFIG_THUNDERBOLT)	+= thunderbolt/
 obj-$(CONFIG_CORESIGHT)		+= hwtracing/coresight/
+obj-$(CONFIG_STM)		+= hwtracing/stm/
 obj-$(CONFIG_ANDROID)		+= android/
 obj-$(CONFIG_NVMEM)		+= nvmem/
diff --git a/drivers/hwtracing/stm/Kconfig b/drivers/hwtracing/stm/Kconfig
new file mode 100644
index 0000000..e101cb4
--- /dev/null
+++ b/drivers/hwtracing/stm/Kconfig
@@ -0,0 +1,8 @@
+config STM
+	tristate "System Trace Module devices"
+	help
+	  A System Trace Module (STM) is a device exporting data in System
+	  Trace Protocol (STP) format as defined by MIPI STP standards.
+	  Examples of such devices are Intel(R) Trace Hub and Coresight STM.
+
+	  Say Y here to enable System Trace Module device support.
diff --git a/drivers/hwtracing/stm/Makefile b/drivers/hwtracing/stm/Makefile
new file mode 100644
index 0000000..adec701
--- /dev/null
+++ b/drivers/hwtracing/stm/Makefile
@@ -0,0 +1,3 @@
+obj-$(CONFIG_STM)	+= stm_core.o
+
+stm_core-y		:= core.o policy.o
diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
new file mode 100644
index 0000000..b79c42c6
--- /dev/null
+++ b/drivers/hwtracing/stm/core.c
@@ -0,0 +1,1029 @@
+/*
+ * System Trace Module (STM) infrastructure
+ * Copyright (c) 2014, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * STM class implements generic infrastructure for  System Trace Module devices
+ * as defined in MIPI STPv2 specification.
+ */
+
+#include <linux/uaccess.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/compat.h>
+#include <linux/kdev_t.h>
+#include <linux/srcu.h>
+#include <linux/slab.h>
+#include <linux/stm.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include "stm.h"
+
+#include <uapi/linux/stm.h>
+
+static unsigned int stm_core_up;
+
+/*
+ * The SRCU here makes sure that STM device doesn't disappear from under a
+ * stm_source_write() caller, which may want to have as little overhead as
+ * possible.
+ */
+static struct srcu_struct stm_source_srcu;
+
+static ssize_t masters_show(struct device *dev,
+			    struct device_attribute *attr,
+			    char *buf)
+{
+	struct stm_device *stm = to_stm_device(dev);
+	int ret;
+
+	ret = sprintf(buf, "%u %u\n", stm->data->sw_start, stm->data->sw_end);
+
+	return ret;
+}
+
+static DEVICE_ATTR_RO(masters);
+
+static ssize_t channels_show(struct device *dev,
+			     struct device_attribute *attr,
+			     char *buf)
+{
+	struct stm_device *stm = to_stm_device(dev);
+	int ret;
+
+	ret = sprintf(buf, "%u\n", stm->data->sw_nchannels);
+
+	return ret;
+}
+
+static DEVICE_ATTR_RO(channels);
+
+static struct attribute *stm_attrs[] = {
+	&dev_attr_masters.attr,
+	&dev_attr_channels.attr,
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(stm);
+
+static struct class stm_class = {
+	.name		= "stm",
+	.dev_groups	= stm_groups,
+};
+
+static int stm_dev_match(struct device *dev, const void *data)
+{
+	const char *name = data;
+
+	return sysfs_streq(name, dev_name(dev));
+}
+
+/**
+ * stm_find_device() - find stm device by name
+ * @buf:	character buffer containing the name
+ *
+ * This is called when either policy gets assigned to an stm device or an
+ * stm_source device gets linked to an stm device.
+ *
+ * This grabs device's reference (get_device()) and module reference, both
+ * of which the calling path needs to make sure to drop with stm_put_device().
+ *
+ * Return:	stm device pointer or null if lookup failed.
+ */
+struct stm_device *stm_find_device(const char *buf)
+{
+	struct stm_device *stm;
+	struct device *dev;
+
+	if (!stm_core_up)
+		return NULL;
+
+	dev = class_find_device(&stm_class, NULL, buf, stm_dev_match);
+	if (!dev)
+		return NULL;
+
+	stm = to_stm_device(dev);
+	if (!try_module_get(stm->owner)) {
+		put_device(dev);
+		return NULL;
+	}
+
+	return stm;
+}
+
+/**
+ * stm_put_device() - drop references on the stm device
+ * @stm:	stm device, previously acquired by stm_find_device()
+ *
+ * This drops the module reference and device reference taken by
+ * stm_find_device().
+ */
+void stm_put_device(struct stm_device *stm)
+{
+	module_put(stm->owner);
+	put_device(&stm->dev);
+}
+
+/*
+ * Internally we only care about software-writable masters here, that is the
+ * ones in the range [stm_data->sw_start..stm_data..sw_end], however we need
+ * original master numbers to be visible externally, since they are the ones
+ * that will appear in the STP stream. Thus, the internal bookkeeping uses
+ * $master - stm_data->sw_start to reference master descriptors and such.
+ */
+
+#define __stm_master(_s, _m)				\
+	((_s)->masters[(_m) - (_s)->data->sw_start])
+
+static inline struct stp_master *
+stm_master(struct stm_device *stm, unsigned int idx)
+{
+	if (idx < stm->data->sw_start || idx > stm->data->sw_end)
+		return NULL;
+
+	return __stm_master(stm, idx);
+}
+
+static int stp_master_alloc(struct stm_device *stm, unsigned int idx)
+{
+	struct stp_master *master;
+	size_t size;
+
+	size = ALIGN(stm->data->sw_nchannels, 8) / 8;
+	size += sizeof(struct stp_master);
+	master = kzalloc(size, GFP_ATOMIC);
+	if (!master)
+		return -ENOMEM;
+
+	master->nr_free = stm->data->sw_nchannels;
+	__stm_master(stm, idx) = master;
+
+	return 0;
+}
+
+static void stp_master_free(struct stm_device *stm, unsigned int idx)
+{
+	struct stp_master *master = stm_master(stm, idx);
+
+	if (!master)
+		return;
+
+	__stm_master(stm, idx) = NULL;
+	kfree(master);
+}
+
+static void stm_output_claim(struct stm_device *stm, struct stm_output *output)
+{
+	struct stp_master *master = stm_master(stm, output->master);
+
+	if (WARN_ON_ONCE(master->nr_free < output->nr_chans))
+		return;
+
+	bitmap_allocate_region(&master->chan_map[0], output->channel,
+			       ilog2(output->nr_chans));
+
+	master->nr_free -= output->nr_chans;
+}
+
+static void
+stm_output_disclaim(struct stm_device *stm, struct stm_output *output)
+{
+	struct stp_master *master = stm_master(stm, output->master);
+
+	bitmap_release_region(&master->chan_map[0], output->channel,
+			      ilog2(output->nr_chans));
+
+	output->nr_chans = 0;
+	master->nr_free += output->nr_chans;
+}
+
+/*
+ * This is like bitmap_find_free_region(), except it can ignore @start bits
+ * at the beginning.
+ */
+static int find_free_channels(unsigned long *bitmap, unsigned int start,
+			      unsigned int end, unsigned int width)
+{
+	unsigned int pos;
+	int i;
+
+	for (pos = start; pos < end + 1; pos = ALIGN(pos, width)) {
+		pos = find_next_zero_bit(bitmap, end + 1, pos);
+		if (pos + width > end + 1)
+			break;
+
+		if (pos & (width - 1))
+			continue;
+
+		for (i = 1; i < width && !test_bit(pos + i, bitmap); i++)
+			;
+		if (i == width)
+			return pos;
+	}
+
+	return -1;
+}
+
+static unsigned int
+stm_find_master_chan(struct stm_device *stm, unsigned int width,
+		     unsigned int *mstart, unsigned int mend,
+		     unsigned int *cstart, unsigned int cend)
+{
+	struct stp_master *master;
+	unsigned int midx;
+	int pos, err;
+
+	for (midx = *mstart; midx <= mend; midx++) {
+		if (!stm_master(stm, midx)) {
+			err = stp_master_alloc(stm, midx);
+			if (err)
+				return err;
+		}
+
+		master = stm_master(stm, midx);
+
+		if (!master->nr_free)
+			continue;
+
+		pos = find_free_channels(master->chan_map, *cstart, cend,
+					 width);
+		if (pos < 0)
+			continue;
+
+		*mstart = midx;
+		*cstart = pos;
+		return 0;
+	}
+
+	return -ENOSPC;
+}
+
+static int stm_output_assign(struct stm_device *stm, unsigned int width,
+			     struct stp_policy_node *policy_node,
+			     struct stm_output *output)
+{
+	unsigned int midx, cidx, mend, cend;
+	int ret = -EINVAL;
+
+	if (width > stm->data->sw_nchannels)
+		return -EINVAL;
+
+	if (policy_node) {
+		stp_policy_node_get_ranges(policy_node,
+					   &midx, &mend, &cidx, &cend);
+	} else {
+		midx = stm->data->sw_start;
+		cidx = 0;
+		mend = stm->data->sw_end;
+		cend = stm->data->sw_nchannels - 1;
+	}
+
+	spin_lock(&stm->mc_lock);
+	/* output is already assigned -- shouldn't happen */
+	if (WARN_ON_ONCE(output->nr_chans))
+		goto unlock;
+
+	ret = stm_find_master_chan(stm, width, &midx, mend, &cidx, cend);
+	if (ret)
+		goto unlock;
+
+	output->master = midx;
+	output->channel = cidx;
+	output->nr_chans = width;
+	stm_output_claim(stm, output);
+	dev_dbg(&stm->dev, "assigned %u:%u (+%u)\n", midx, cidx, width);
+
+	ret = 0;
+unlock:
+	spin_unlock(&stm->mc_lock);
+
+	return ret;
+}
+
+static void stm_output_free(struct stm_device *stm, struct stm_output *output)
+{
+	spin_lock(&stm->mc_lock);
+	if (output->nr_chans)
+		stm_output_disclaim(stm, output);
+	spin_unlock(&stm->mc_lock);
+}
+
+static int major_match(struct device *dev, const void *data)
+{
+	unsigned int major = *(unsigned int *)data;
+
+	return MAJOR(dev->devt) == major;
+}
+
+static int stm_char_open(struct inode *inode, struct file *file)
+{
+	struct stm_file *stmf;
+	struct device *dev;
+	unsigned int major = imajor(inode);
+	int err = -ENODEV;
+
+	dev = class_find_device(&stm_class, NULL, &major, major_match);
+	if (!dev)
+		return -ENODEV;
+
+	stmf = kzalloc(sizeof(*stmf), GFP_KERNEL);
+	if (!stmf)
+		return -ENOMEM;
+
+	stmf->stm = to_stm_device(dev);
+
+	if (!try_module_get(stmf->stm->owner))
+		goto err_free;
+
+	file->private_data = stmf;
+
+	return nonseekable_open(inode, file);
+
+err_free:
+	kfree(stmf);
+
+	return err;
+}
+
+static int stm_char_release(struct inode *inode, struct file *file)
+{
+	struct stm_file *stmf = file->private_data;
+
+	stm_output_free(stmf->stm, &stmf->output);
+	stm_put_device(stmf->stm);
+	kfree(stmf);
+
+	return 0;
+}
+
+static int stm_file_assign(struct stm_file *stmf, char *id, unsigned int width)
+{
+	struct stm_device *stm = stmf->stm;
+	int ret;
+
+	stmf->policy_node = stp_policy_node_lookup(stm, id);
+
+	ret = stm_output_assign(stm, width, stmf->policy_node, &stmf->output);
+
+	if (stmf->policy_node)
+		stp_policy_node_put(stmf->policy_node);
+
+	return ret;
+}
+
+static void stm_write(struct stm_data *data, unsigned int master,
+		      unsigned int channel, const char *buf, size_t count)
+{
+	unsigned int flags = STP_PACKET_TIMESTAMPED;
+	const unsigned char *p = buf, nil = 0;
+	size_t pos;
+	ssize_t sz;
+
+	for (pos = 0, p = buf; count > pos; pos += sz, p += sz) {
+		sz = min_t(unsigned int, count - pos, 8);
+		sz = data->packet(data, master, channel, STP_PACKET_DATA, flags,
+				  sz, p);
+		flags = 0;
+	}
+
+	data->packet(data, master, channel, STP_PACKET_FLAG, 0, 0, &nil);
+}
+
+static ssize_t stm_char_write(struct file *file, const char __user *buf,
+			      size_t count, loff_t *ppos)
+{
+	struct stm_file *stmf = file->private_data;
+	struct stm_device *stm = stmf->stm;
+	char *kbuf;
+	int err;
+
+	/*
+	 * if no m/c have been assigned to this writer up to this
+	 * point, use "default" policy entry
+	 */
+	if (!stmf->output.nr_chans) {
+		err = stm_file_assign(stmf, "default", 1);
+		/*
+		 * EBUSY means that somebody else just assigned this
+		 * output, which is just fine for write()
+		 */
+		if (err && err != -EBUSY)
+			return err;
+	}
+
+	kbuf = kmalloc(count + 1, GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	err = copy_from_user(kbuf, buf, count);
+	if (err) {
+		kfree(kbuf);
+		return -EFAULT;
+	}
+
+	stm_write(stm->data, stmf->output.master, stmf->output.channel, kbuf,
+		  count);
+
+	kfree(kbuf);
+
+	return count;
+}
+
+static int stm_char_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct stm_file *stmf = file->private_data;
+	struct stm_device *stm = stmf->stm;
+	unsigned long size, phys;
+
+	if (!stm->data->mmio_addr)
+		return -EOPNOTSUPP;
+
+	if (vma->vm_pgoff)
+		return -EINVAL;
+
+	size = vma->vm_end - vma->vm_start;
+
+	if (stmf->output.nr_chans * stm->data->sw_mmiosz != size)
+		return -EINVAL;
+
+	phys = stm->data->mmio_addr(stm->data, stmf->output.master,
+				    stmf->output.channel,
+				    stmf->output.nr_chans);
+
+	if (!phys)
+		return -EINVAL;
+
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+	vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
+	vm_iomap_memory(vma, phys, size);
+
+	return 0;
+}
+
+static int stm_char_policy_set_ioctl(struct stm_file *stmf, void __user *arg)
+{
+	struct stm_device *stm = stmf->stm;
+	struct stp_policy_id *id;
+	int ret = -EINVAL;
+	u32 size;
+
+	if (stmf->output.nr_chans)
+		return -EBUSY;
+
+	if (copy_from_user(&size, arg, sizeof(size)))
+		return -EFAULT;
+
+	if (size >= PATH_MAX + sizeof(*id))
+		return -EINVAL;
+
+	/*
+	 * size + 1 to make sure the .id string at the bottom is terminated,
+	 * which is also why memdup_user() is not useful here
+	 */
+	id = kzalloc(size + 1, GFP_KERNEL);
+	if (!id)
+		return -ENOMEM;
+
+	if (copy_from_user(id, arg, size)) {
+		ret = -EFAULT;
+		goto err_free;
+	}
+
+	if (id->__reserved_0 || id->__reserved_1)
+		goto err_free;
+
+	if (id->width < 1 ||
+	    id->width > PAGE_SIZE / stm->data->sw_mmiosz)
+		goto err_free;
+
+	ret = stm_file_assign(stmf, id->id, id->width);
+	if (ret)
+		goto err_free;
+
+	ret = 0;
+
+	if (stm->data->link)
+		ret = stm->data->link(stm->data, stmf->output.master,
+				      stmf->output.channel);
+
+	if (ret) {
+		stm_output_free(stmf->stm, &stmf->output);
+		stm_put_device(stmf->stm);
+	}
+
+err_free:
+	kfree(id);
+
+	return ret;
+}
+
+static int stm_char_policy_get_ioctl(struct stm_file *stmf, void __user *arg)
+{
+	struct stp_policy_id id = {
+		.size		= sizeof(id),
+		.master		= stmf->output.master,
+		.channel	= stmf->output.channel,
+		.width		= stmf->output.nr_chans,
+		.__reserved_0	= 0,
+		.__reserved_1	= 0,
+	};
+
+	return copy_to_user(arg, &id, id.size) ? -EFAULT : 0;
+}
+
+static long
+stm_char_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct stm_file *stmf = file->private_data;
+	struct stm_data *stm_data = stmf->stm->data;
+	int err = -ENOTTY;
+	u64 options;
+
+	switch (cmd) {
+	case STP_POLICY_ID_SET:
+		err = stm_char_policy_set_ioctl(stmf, (void __user *)arg);
+		if (err)
+			return err;
+
+		return stm_char_policy_get_ioctl(stmf, (void __user *)arg);
+
+	case STP_POLICY_ID_GET:
+		return stm_char_policy_get_ioctl(stmf, (void __user *)arg);
+
+	case STP_SET_OPTIONS:
+		if (copy_from_user(&options, (u64 __user *)arg, sizeof(u64)))
+			return -EFAULT;
+
+		if (stm_data->set_options)
+			err = stm_data->set_options(stm_data,
+						    stmf->output.master,
+						    stmf->output.channel,
+						    stmf->output.nr_chans,
+						    options);
+
+		break;
+	default:
+		break;
+	}
+
+	return err;
+}
+
+#ifdef CONFIG_COMPAT
+static long
+stm_char_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	return stm_char_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
+}
+#else
+#define stm_char_compat_ioctl	NULL
+#endif
+
+static const struct file_operations stm_fops = {
+	.open		= stm_char_open,
+	.release	= stm_char_release,
+	.write		= stm_char_write,
+	.mmap		= stm_char_mmap,
+	.unlocked_ioctl	= stm_char_ioctl,
+	.compat_ioctl	= stm_char_compat_ioctl,
+	.llseek		= no_llseek,
+};
+
+static void stm_device_release(struct device *dev)
+{
+	struct stm_device *stm = to_stm_device(dev);
+
+	kfree(stm);
+}
+
+int stm_register_device(struct device *parent, struct stm_data *stm_data,
+			struct module *owner)
+{
+	struct stm_device *stm;
+	unsigned int nmasters;
+	int err = -ENOMEM;
+
+	if (!stm_core_up)
+		return -EPROBE_DEFER;
+
+	if (!stm_data->packet || !stm_data->sw_nchannels)
+		return -EINVAL;
+
+	nmasters = stm_data->sw_end - stm_data->sw_start;
+	stm = kzalloc(sizeof(*stm) + nmasters * sizeof(void *), GFP_KERNEL);
+	if (!stm)
+		return -ENOMEM;
+
+	stm->major = register_chrdev(0, stm_data->name, &stm_fops);
+	if (stm->major < 0)
+		goto err_free;
+
+	device_initialize(&stm->dev);
+	stm->dev.devt = MKDEV(stm->major, 0);
+	stm->dev.class = &stm_class;
+	stm->dev.parent = parent;
+	stm->dev.release = stm_device_release;
+
+	err = kobject_set_name(&stm->dev.kobj, "%s", stm_data->name);
+	if (err)
+		goto err_device;
+
+	err = device_add(&stm->dev);
+	if (err)
+		goto err_device;
+
+	spin_lock_init(&stm->link_lock);
+	INIT_LIST_HEAD(&stm->link_list);
+
+	spin_lock_init(&stm->mc_lock);
+	mutex_init(&stm->policy_mutex);
+	stm->sw_nmasters = nmasters;
+	stm->owner = owner;
+	stm->data = stm_data;
+	stm_data->stm = stm;
+
+	return 0;
+
+err_device:
+	put_device(&stm->dev);
+err_free:
+	kfree(stm);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(stm_register_device);
+
+static void __stm_source_link_drop(struct stm_source_device *src,
+				   struct stm_device *stm);
+
+void stm_unregister_device(struct stm_data *stm_data)
+{
+	struct stm_device *stm = stm_data->stm;
+	struct stm_source_device *src, *iter;
+	int i;
+
+	spin_lock(&stm->link_lock);
+	list_for_each_entry_safe(src, iter, &stm->link_list, link_entry) {
+		__stm_source_link_drop(src, stm);
+	}
+	spin_unlock(&stm->link_lock);
+
+	synchronize_srcu(&stm_source_srcu);
+
+	unregister_chrdev(stm->major, stm_data->name);
+
+	mutex_lock(&stm->policy_mutex);
+	if (stm->policy)
+		stp_policy_unbind(stm->policy);
+	mutex_unlock(&stm->policy_mutex);
+
+	for (i = 0; i < stm->sw_nmasters; i++)
+		stp_master_free(stm, i);
+
+	device_unregister(&stm->dev);
+	stm_data->stm = NULL;
+}
+EXPORT_SYMBOL_GPL(stm_unregister_device);
+
+/**
+ * stm_source_link_add() - connect an stm_source device to an stm device
+ * @src:	stm_source device
+ * @stm:	stm device
+ *
+ * This function establishes a link from stm_source to an stm device so that
+ * the former can send out trace data to the latter.
+ *
+ * Return:	0 on success, -errno otherwise.
+ */
+static int stm_source_link_add(struct stm_source_device *src,
+			       struct stm_device *stm)
+{
+	char *id;
+	int err;
+
+	spin_lock(&stm->link_lock);
+	spin_lock(&src->link_lock);
+
+	/* src->link is dereferenced under stm_source_srcu but not the list */
+	rcu_assign_pointer(src->link, stm);
+	list_add_tail(&src->link_entry, &stm->link_list);
+
+	spin_unlock(&src->link_lock);
+	spin_unlock(&stm->link_lock);
+
+	id = kstrdup(src->data->name, GFP_KERNEL);
+	if (id) {
+		src->policy_node =
+			stp_policy_node_lookup(stm, id);
+
+		kfree(id);
+	}
+
+	err = stm_output_assign(stm, src->data->nr_chans,
+				src->policy_node, &src->output);
+
+	if (src->policy_node)
+		stp_policy_node_put(src->policy_node);
+
+	if (err)
+		goto fail_detach;
+
+	/* this is to notify the STM device that a new link has been made */
+	if (stm->data->link)
+		err = stm->data->link(stm->data, src->output.master,
+				      src->output.channel);
+
+	if (err)
+		goto fail_free_output;
+
+	/* this is to let the source carry out all necessary preparations */
+	if (src->data->link)
+		src->data->link(src->data);
+
+	return 0;
+
+fail_free_output:
+	stm_output_free(stm, &src->output);
+	stm_put_device(stm);
+
+fail_detach:
+	spin_lock(&stm->link_lock);
+	spin_lock(&src->link_lock);
+
+	rcu_assign_pointer(src->link, NULL);
+	list_del_init(&src->link_entry);
+
+	spin_unlock(&src->link_lock);
+	spin_unlock(&stm->link_lock);
+
+	return err;
+}
+
+/**
+ * __stm_source_link_drop() - detach stm_source from an stm device
+ * @src:	stm_source device
+ * @stm:	stm device
+ *
+ * If @stm is @src::link, disconnect them from one another and put the
+ * reference on the @stm device.
+ *
+ * Caller must hold stm::link_lock.
+ */
+static void __stm_source_link_drop(struct stm_source_device *src,
+				   struct stm_device *stm)
+{
+	spin_lock(&src->link_lock);
+	if (WARN_ON_ONCE(src->link != stm)) {
+		spin_unlock(&src->link_lock);
+		return;
+	}
+
+	stm_output_free(src->link, &src->output);
+	/* caller must hold stm::link_lock */
+	list_del_init(&src->link_entry);
+	/* matches stm_find_device() from stm_source_link_store() */
+	stm_put_device(src->link);
+	rcu_assign_pointer(src->link, NULL);
+
+	spin_unlock(&src->link_lock);
+}
+
+/**
+ * stm_source_link_drop() - detach stm_source from its stm device
+ * @src:	stm_source device
+ *
+ * Unlinking means disconnecting from source's STM device; after this
+ * writes will be unsuccessful until it is linked to a new STM device.
+ *
+ * This will happen on "stm_source_link" sysfs attribute write to undo
+ * the existing link (if any), or on linked STM device's de-registration.
+ */
+static void stm_source_link_drop(struct stm_source_device *src)
+{
+	struct stm_device *stm;
+	int idx;
+
+	idx = srcu_read_lock(&stm_source_srcu);
+	stm = srcu_dereference(src->link, &stm_source_srcu);
+
+	if (stm) {
+		if (src->data->unlink)
+			src->data->unlink(src->data);
+
+		spin_lock(&stm->link_lock);
+		__stm_source_link_drop(src, stm);
+		spin_unlock(&stm->link_lock);
+	}
+
+	srcu_read_unlock(&stm_source_srcu, idx);
+}
+
+static ssize_t stm_source_link_show(struct device *dev,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct stm_source_device *src = to_stm_source_device(dev);
+	struct stm_device *stm;
+	int idx, ret;
+
+	idx = srcu_read_lock(&stm_source_srcu);
+	stm = srcu_dereference(src->link, &stm_source_srcu);
+	ret = sprintf(buf, "%s\n",
+		      stm ? dev_name(&stm->dev) : "<none>");
+	srcu_read_unlock(&stm_source_srcu, idx);
+
+	return ret;
+}
+
+static ssize_t stm_source_link_store(struct device *dev,
+				     struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	struct stm_source_device *src = to_stm_source_device(dev);
+	struct stm_device *link;
+	int err;
+
+	stm_source_link_drop(src);
+
+	link = stm_find_device(buf);
+	if (!link)
+		return -EINVAL;
+
+	err = stm_source_link_add(src, link);
+	if (err)
+		stm_put_device(link);
+
+	return err ? : count;
+}
+
+static DEVICE_ATTR_RW(stm_source_link);
+
+static struct attribute *stm_source_attrs[] = {
+	&dev_attr_stm_source_link.attr,
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(stm_source);
+
+static struct class stm_source_class = {
+	.name		= "stm_source",
+	.dev_groups	= stm_source_groups,
+};
+
+static void stm_source_device_release(struct device *dev)
+{
+	struct stm_source_device *src = to_stm_source_device(dev);
+
+	kfree(src);
+}
+
+/**
+ * stm_source_register_device() - register an stm_source device
+ * @parent:	parent device
+ * @data:	device description structure
+ *
+ * This will create a device of stm_source class that can write
+ * data to an stm device once linked.
+ *
+ * Return:	0 on success, -errno otherwise.
+ */
+int stm_source_register_device(struct device *parent,
+			       struct stm_source_data *data)
+{
+	struct stm_source_device *src;
+	int err;
+
+	if (!stm_core_up)
+		return -EPROBE_DEFER;
+
+	src = kzalloc(sizeof(*src), GFP_KERNEL);
+	if (!src)
+		return -ENOMEM;
+
+	device_initialize(&src->dev);
+	src->dev.class = &stm_source_class;
+	src->dev.parent = parent;
+	src->dev.release = stm_source_device_release;
+
+	err = kobject_set_name(&src->dev.kobj, "%s", data->name);
+	if (err)
+		goto err;
+
+	err = device_add(&src->dev);
+	if (err)
+		goto err;
+
+	spin_lock_init(&src->link_lock);
+	INIT_LIST_HEAD(&src->link_entry);
+	src->data = data;
+	data->src = src;
+
+	return 0;
+
+err:
+	put_device(&src->dev);
+	kfree(src);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(stm_source_register_device);
+
+/**
+ * stm_source_unregister_device() - unregister an stm_source device
+ * @data:	device description that was used to register the device
+ *
+ * This will remove a previously created stm_source device from the system.
+ */
+void stm_source_unregister_device(struct stm_source_data *data)
+{
+	struct stm_source_device *src = data->src;
+
+	stm_source_link_drop(src);
+
+	device_destroy(&stm_source_class, src->dev.devt);
+}
+EXPORT_SYMBOL_GPL(stm_source_unregister_device);
+
+int stm_source_write(struct stm_source_data *data, unsigned int chan,
+		     const char *buf, size_t count)
+{
+	struct stm_source_device *src = data->src;
+	struct stm_device *stm;
+	int idx;
+
+	if (!src->output.nr_chans)
+		return -ENODEV;
+
+	if (chan >= src->output.nr_chans)
+		return -EINVAL;
+
+	idx = srcu_read_lock(&stm_source_srcu);
+
+	stm = srcu_dereference(src->link, &stm_source_srcu);
+	if (stm)
+		stm_write(stm->data, src->output.master,
+			  src->output.channel + chan,
+			  buf, count);
+	else
+		count = -ENODEV;
+
+	srcu_read_unlock(&stm_source_srcu, idx);
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(stm_source_write);
+
+static int __init stm_core_init(void)
+{
+	int err;
+
+	err = class_register(&stm_class);
+	if (err)
+		return err;
+
+	err = class_register(&stm_source_class);
+	if (err)
+		goto err_stm;
+
+	err = stp_configfs_init();
+	if (err)
+		goto err_src;
+
+	init_srcu_struct(&stm_source_srcu);
+
+	stm_core_up++;
+
+	return 0;
+
+err_src:
+	class_unregister(&stm_source_class);
+err_stm:
+	class_unregister(&stm_class);
+
+	return err;
+}
+
+module_init(stm_core_init);
+
+static void __exit stm_core_exit(void)
+{
+	cleanup_srcu_struct(&stm_source_srcu);
+	class_unregister(&stm_source_class);
+	class_unregister(&stm_class);
+	stp_configfs_exit();
+}
+
+module_exit(stm_core_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("System Trace Module device class");
+MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");
diff --git a/drivers/hwtracing/stm/policy.c b/drivers/hwtracing/stm/policy.c
new file mode 100644
index 0000000..6498a9d
--- /dev/null
+++ b/drivers/hwtracing/stm/policy.c
@@ -0,0 +1,529 @@
+/*
+ * System Trace Module (STM) master/channel allocation policy management
+ * Copyright (c) 2014, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * A master/channel allocation policy allows mapping string identifiers to
+ * master and channel ranges, where allocation can be done.
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/configfs.h>
+#include <linux/slab.h>
+#include <linux/stm.h>
+#include "stm.h"
+
+/*
+ * STP Master/Channel allocation policy configfs layout.
+ */
+
+struct stp_policy {
+	struct config_group	group;
+	struct stm_device	*stm;
+};
+
+struct stp_policy_node {
+	struct config_group	group;
+	struct stp_policy	*policy;
+	unsigned int		first_master;
+	unsigned int		last_master;
+	unsigned int		first_channel;
+	unsigned int		last_channel;
+};
+
+static struct configfs_subsystem stp_policy_subsys;
+
+void stp_policy_node_get_ranges(struct stp_policy_node *policy_node,
+				unsigned int *mstart, unsigned int *mend,
+				unsigned int *cstart, unsigned int *cend)
+{
+	*mstart	= policy_node->first_master;
+	*mend	= policy_node->last_master;
+	*cstart	= policy_node->first_channel;
+	*cend	= policy_node->last_channel;
+}
+
+static inline char *stp_policy_node_name(struct stp_policy_node *policy_node)
+{
+	return policy_node->group.cg_item.ci_name ? : "<none>";
+}
+
+static inline struct stp_policy *to_stp_policy(struct config_item *item)
+{
+	return item ?
+		container_of(to_config_group(item), struct stp_policy, group) :
+		NULL;
+}
+
+static inline struct stp_policy_node *
+to_stp_policy_node(struct config_item *item)
+{
+	return item ?
+		container_of(to_config_group(item), struct stp_policy_node,
+			     group) :
+		NULL;
+}
+
+static ssize_t stp_policy_node_masters_show(struct stp_policy_node *policy_node,
+					    char *page)
+{
+	ssize_t count;
+
+	count = sprintf(page, "%u %u\n", policy_node->first_master,
+			policy_node->last_master);
+
+	return count;
+}
+
+static ssize_t
+stp_policy_node_masters_store(struct stp_policy_node *policy_node,
+			      const char *page, size_t count)
+{
+	unsigned int first, last;
+	struct stm_device *stm;
+	char *p = (char *)page;
+	ssize_t ret = -ENODEV;
+
+	if (sscanf(p, "%u %u", &first, &last) != 2)
+		return -EINVAL;
+
+	mutex_lock(&stp_policy_subsys.su_mutex);
+	stm = policy_node->policy->stm;
+	if (!stm)
+		goto unlock;
+
+	/* must be within [sw_start..sw_end], which is an inclusive range */
+	if (first > INT_MAX || last > INT_MAX || first > last ||
+	    first < stm->data->sw_start ||
+	    last > stm->data->sw_end) {
+		ret = -ERANGE;
+		goto unlock;
+	}
+
+	ret = count;
+	policy_node->first_master = first;
+	policy_node->last_master = last;
+
+unlock:
+	mutex_unlock(&stp_policy_subsys.su_mutex);
+
+	return ret;
+}
+
+static ssize_t
+stp_policy_node_channels_show(struct stp_policy_node *policy_node, char *page)
+{
+	ssize_t count;
+
+	count = sprintf(page, "%u %u\n", policy_node->first_channel,
+			policy_node->last_channel);
+
+	return count;
+}
+
+static ssize_t
+stp_policy_node_channels_store(struct stp_policy_node *policy_node,
+			       const char *page, size_t count)
+{
+	unsigned int first, last;
+	struct stm_device *stm;
+	char *p = (char *)page;
+	ssize_t ret = -ENODEV;
+
+	if (sscanf(p, "%u %u", &first, &last) != 2)
+		return -EINVAL;
+
+	mutex_lock(&stp_policy_subsys.su_mutex);
+	stm = policy_node->policy->stm;
+	if (!stm)
+		goto unlock;
+
+	if (first > INT_MAX || last > INT_MAX || first > last ||
+	    last >= stm->data->sw_nchannels) {
+		ret = -ERANGE;
+		goto unlock;
+	}
+
+	ret = count;
+	policy_node->first_channel = first;
+	policy_node->last_channel = last;
+
+unlock:
+	mutex_unlock(&stp_policy_subsys.su_mutex);
+
+	return ret;
+}
+
+static void stp_policy_node_release(struct config_item *item)
+{
+	kfree(to_stp_policy_node(item));
+}
+
+struct stp_policy_node_attribute {
+	struct configfs_attribute	attr;
+	ssize_t (*show)(struct stp_policy_node *, char *);
+	ssize_t (*store)(struct stp_policy_node *, const char *, size_t);
+};
+
+static ssize_t stp_policy_node_attr_show(struct config_item *item,
+					 struct configfs_attribute *attr,
+					 char *page)
+{
+	struct stp_policy_node *policy_node = to_stp_policy_node(item);
+	struct stp_policy_node_attribute *pn_attr =
+		container_of(attr, struct stp_policy_node_attribute, attr);
+	ssize_t count = 0;
+
+	if (pn_attr->show)
+		count = pn_attr->show(policy_node, page);
+
+	return count;
+}
+
+static ssize_t stp_policy_node_attr_store(struct config_item *item,
+					  struct configfs_attribute *attr,
+					  const char *page, size_t len)
+{
+	struct stp_policy_node *policy_node = to_stp_policy_node(item);
+	struct stp_policy_node_attribute *pn_attr =
+		container_of(attr, struct stp_policy_node_attribute, attr);
+	ssize_t count = -EINVAL;
+
+	if (pn_attr->store)
+		count = pn_attr->store(policy_node, page, len);
+
+	return count;
+}
+
+static struct configfs_item_operations stp_policy_node_item_ops = {
+	.release		= stp_policy_node_release,
+	.show_attribute		= stp_policy_node_attr_show,
+	.store_attribute	= stp_policy_node_attr_store,
+};
+
+static struct stp_policy_node_attribute stp_policy_node_attr_range = {
+	.attr	= {
+		.ca_owner = THIS_MODULE,
+		.ca_name = "masters",
+		.ca_mode = S_IRUGO | S_IWUSR,
+	},
+	.show	= stp_policy_node_masters_show,
+	.store	= stp_policy_node_masters_store,
+};
+
+static struct stp_policy_node_attribute stp_policy_node_attr_channels = {
+	.attr	= {
+		.ca_owner = THIS_MODULE,
+		.ca_name = "channels",
+		.ca_mode = S_IRUGO | S_IWUSR,
+	},
+	.show	= stp_policy_node_channels_show,
+	.store	= stp_policy_node_channels_store,
+};
+
+static struct configfs_attribute *stp_policy_node_attrs[] = {
+	&stp_policy_node_attr_range.attr,
+	&stp_policy_node_attr_channels.attr,
+	NULL,
+};
+
+static struct config_item_type stp_policy_type;
+static struct config_item_type stp_policy_node_type;
+
+static struct config_group *
+stp_policy_node_make(struct config_group *group, const char *name)
+{
+	struct stp_policy_node *policy_node, *parent_node;
+	struct stp_policy *policy;
+
+	if (group->cg_item.ci_type == &stp_policy_type) {
+		policy = container_of(group, struct stp_policy, group);
+	} else {
+		parent_node = container_of(group, struct stp_policy_node,
+					   group);
+		policy = parent_node->policy;
+	}
+
+	if (!policy->stm)
+		return ERR_PTR(-ENODEV);
+
+	policy_node = kzalloc(sizeof(struct stp_policy_node), GFP_KERNEL);
+	if (!policy_node)
+		return ERR_PTR(-ENOMEM);
+
+	config_group_init_type_name(&policy_node->group, name,
+				    &stp_policy_node_type);
+
+	policy_node->policy = policy;
+
+	/* default values for the attributes */
+	policy_node->first_master = policy->stm->data->sw_start;
+	policy_node->last_master = policy->stm->data->sw_end;
+	policy_node->first_channel = 0;
+	policy_node->last_channel = policy->stm->data->sw_nchannels - 1;
+
+	return &policy_node->group;
+}
+
+static void
+stp_policy_node_drop(struct config_group *group, struct config_item *item)
+{
+	config_item_put(item);
+}
+
+static struct configfs_group_operations stp_policy_node_group_ops = {
+	.make_group	= stp_policy_node_make,
+	.drop_item	= stp_policy_node_drop,
+};
+
+static struct config_item_type stp_policy_node_type = {
+	.ct_item_ops	= &stp_policy_node_item_ops,
+	.ct_group_ops	= &stp_policy_node_group_ops,
+	.ct_attrs	= stp_policy_node_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+/*
+ * Root group: policies.
+ */
+static struct configfs_attribute stp_policy_attr_device = {
+	.ca_owner = THIS_MODULE,
+	.ca_name = "device",
+	.ca_mode = S_IRUGO,
+};
+
+static struct configfs_attribute *stp_policy_attrs[] = {
+	&stp_policy_attr_device,
+	NULL,
+};
+
+static ssize_t stp_policy_attr_show(struct config_item *item,
+				    struct configfs_attribute *attr,
+				    char *page)
+{
+	struct stp_policy *policy = to_stp_policy(item);
+	ssize_t count;
+
+	count = sprintf(page, "%s\n",
+			(policy && policy->stm) ?
+			policy->stm->data->name :
+			"<none>");
+
+	return count;
+}
+
+void stp_policy_unbind(struct stp_policy *policy)
+{
+	struct stm_device *stm = policy->stm;
+
+	if (WARN_ON_ONCE(!policy->stm))
+		return;
+
+	mutex_lock(&stm->policy_mutex);
+	stm->policy = NULL;
+	mutex_unlock(&stm->policy_mutex);
+
+	policy->stm = NULL;
+
+	stm_put_device(stm);
+}
+
+static void stp_policy_release(struct config_item *item)
+{
+	struct stp_policy *policy = to_stp_policy(item);
+
+	stp_policy_unbind(policy);
+	kfree(policy);
+}
+
+static struct configfs_item_operations stp_policy_item_ops = {
+	.release		= stp_policy_release,
+	.show_attribute		= stp_policy_attr_show,
+};
+
+static struct configfs_group_operations stp_policy_group_ops = {
+	.make_group	= stp_policy_node_make,
+};
+
+static struct config_item_type stp_policy_type = {
+	.ct_item_ops	= &stp_policy_item_ops,
+	.ct_group_ops	= &stp_policy_group_ops,
+	.ct_attrs	= stp_policy_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_group *
+stp_policies_make(struct config_group *group, const char *name)
+{
+	struct config_group *ret;
+	struct stm_device *stm;
+	char *devname, *p;
+
+	devname = kasprintf(GFP_KERNEL, "%s", name);
+	if (!devname)
+		return ERR_PTR(-ENOMEM);
+
+	/*
+	 * node must look like <device_name>.<policy_name>, where
+	 * <device_name> is the name of an existing stm device and
+	 * <policy_name> is an arbitrary string
+	 */
+	p = strchr(devname, '.');
+	if (!p) {
+		kfree(devname);
+		return ERR_PTR(-EINVAL);
+	}
+
+	*p++ = '\0';
+
+	stm = stm_find_device(devname);
+	kfree(devname);
+
+	if (!stm)
+		return ERR_PTR(-ENODEV);
+
+	mutex_lock(&stm->policy_mutex);
+	if (stm->policy) {
+		ret = ERR_PTR(-EBUSY);
+		goto unlock_policy;
+	}
+
+	stm->policy = kzalloc(sizeof(*stm->policy), GFP_KERNEL);
+	if (!stm->policy) {
+		ret = ERR_PTR(-ENOMEM);
+		goto unlock_policy;
+	}
+
+	config_group_init_type_name(&stm->policy->group, name,
+				    &stp_policy_type);
+	stm->policy->stm = stm;
+
+	ret = &stm->policy->group;
+
+unlock_policy:
+	mutex_unlock(&stm->policy_mutex);
+
+	if (IS_ERR(ret))
+		stm_put_device(stm);
+
+	return ret;
+}
+
+static struct configfs_group_operations stp_policies_group_ops = {
+	.make_group	= stp_policies_make,
+};
+
+static struct config_item_type stp_policies_type = {
+	.ct_group_ops	= &stp_policies_group_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct configfs_subsystem stp_policy_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf	= "stp-policy",
+			.ci_type	= &stp_policies_type,
+		},
+	},
+};
+
+/*
+ * Lock the policy mutex from the outside
+ */
+static struct stp_policy_node *
+__stp_policy_node_lookup(struct stp_policy *policy, char *s)
+{
+	struct stp_policy_node *policy_node, *ret;
+	struct list_head *head = &policy->group.cg_children;
+	struct config_item *item;
+	char *start, *end = s;
+
+	if (list_empty(head))
+		return NULL;
+
+	/* return the first entry if everything else fails */
+	item = list_entry(head->next, struct config_item, ci_entry);
+	ret = to_stp_policy_node(item);
+
+next:
+	for (;;) {
+		start = strsep(&end, "/");
+		if (!start)
+			break;
+
+		if (!*start)
+			continue;
+
+		list_for_each_entry(item, head, ci_entry) {
+			policy_node = to_stp_policy_node(item);
+
+			if (!strcmp(start,
+				    policy_node->group.cg_item.ci_name)) {
+				ret = policy_node;
+
+				if (!end)
+					goto out;
+
+				head = &policy_node->group.cg_children;
+				goto next;
+			}
+		}
+		break;
+	}
+
+out:
+	return ret;
+}
+
+
+struct stp_policy_node *
+stp_policy_node_lookup(struct stm_device *stm, char *s)
+{
+	struct stp_policy_node *policy_node = NULL;
+
+	mutex_lock(&stp_policy_subsys.su_mutex);
+
+	mutex_lock(&stm->policy_mutex);
+	if (stm->policy)
+		policy_node = __stp_policy_node_lookup(stm->policy, s);
+	mutex_unlock(&stm->policy_mutex);
+
+	if (policy_node)
+		config_item_get(&policy_node->group.cg_item);
+	mutex_unlock(&stp_policy_subsys.su_mutex);
+
+	return policy_node;
+}
+
+void stp_policy_node_put(struct stp_policy_node *policy_node)
+{
+	config_item_put(&policy_node->group.cg_item);
+}
+
+int __init stp_configfs_init(void)
+{
+	int err;
+
+	config_group_init(&stp_policy_subsys.su_group);
+	mutex_init(&stp_policy_subsys.su_mutex);
+	err = configfs_register_subsystem(&stp_policy_subsys);
+
+	return err;
+}
+
+void __exit stp_configfs_exit(void)
+{
+	configfs_unregister_subsystem(&stp_policy_subsys);
+}
diff --git a/drivers/hwtracing/stm/stm.h b/drivers/hwtracing/stm/stm.h
new file mode 100644
index 0000000..cf33bf9
--- /dev/null
+++ b/drivers/hwtracing/stm/stm.h
@@ -0,0 +1,87 @@
+/*
+ * System Trace Module (STM) infrastructure
+ * Copyright (c) 2014, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * STM class implements generic infrastructure for  System Trace Module devices
+ * as defined in MIPI STPv2 specification.
+ */
+
+#ifndef _STM_STM_H_
+#define _STM_STM_H_
+
+struct stp_policy;
+struct stp_policy_node;
+
+struct stp_policy_node *
+stp_policy_node_lookup(struct stm_device *stm, char *s);
+void stp_policy_node_put(struct stp_policy_node *policy_node);
+void stp_policy_unbind(struct stp_policy *policy);
+
+void stp_policy_node_get_ranges(struct stp_policy_node *policy_node,
+				unsigned int *mstart, unsigned int *mend,
+				unsigned int *cstart, unsigned int *cend);
+int stp_configfs_init(void);
+void stp_configfs_exit(void);
+
+struct stp_master {
+	unsigned int	nr_free;
+	unsigned long	chan_map[0];
+};
+
+struct stm_device {
+	struct device		dev;
+	struct module		*owner;
+	struct stp_policy	*policy;
+	struct mutex		policy_mutex;
+	int			major;
+	unsigned int		sw_nmasters;
+	struct stm_data		*data;
+	spinlock_t		link_lock;
+	struct list_head	link_list;
+	/* master allocation */
+	spinlock_t		mc_lock;
+	struct stp_master	*masters[0];
+};
+
+#define to_stm_device(_d)				\
+	container_of((_d), struct stm_device, dev)
+
+struct stm_output {
+	unsigned int		master;
+	unsigned int		channel;
+	unsigned int		nr_chans;
+};
+
+struct stm_file {
+	struct stm_device	*stm;
+	struct stp_policy_node	*policy_node;
+	struct stm_output	output;
+};
+
+struct stm_device *stm_find_device(const char *name);
+void stm_put_device(struct stm_device *stm);
+
+struct stm_source_device {
+	struct device		dev;
+	struct stm_source_data	*data;
+	spinlock_t		link_lock;
+	struct stm_device	*link;
+	struct list_head	link_entry;
+	/* one output per stm_source device */
+	struct stp_policy_node	*policy_node;
+	struct stm_output	output;
+};
+
+#define to_stm_source_device(_d)				\
+	container_of((_d), struct stm_source_device, dev)
+
+#endif /* _STM_STM_H_ */
diff --git a/include/linux/stm.h b/include/linux/stm.h
new file mode 100644
index 0000000..9d0083d
--- /dev/null
+++ b/include/linux/stm.h
@@ -0,0 +1,126 @@
+/*
+ * System Trace Module (STM) infrastructure apis
+ * Copyright (C) 2014 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#ifndef _STM_H_
+#define _STM_H_
+
+#include <linux/device.h>
+
+/**
+ * enum stp_packet_type - STP packets that an STM driver sends
+ */
+enum stp_packet_type {
+	STP_PACKET_DATA = 0,
+	STP_PACKET_FLAG,
+	STP_PACKET_USER,
+	STP_PACKET_MERR,
+	STP_PACKET_GERR,
+	STP_PACKET_TRIG,
+	STP_PACKET_XSYNC,
+};
+
+/**
+ * enum stp_packet_flags - STP packet modifiers
+ */
+enum stp_packet_flags {
+	STP_PACKET_MARKED	= 0x1,
+	STP_PACKET_TIMESTAMPED	= 0x2,
+};
+
+struct stp_policy;
+
+struct stm_device;
+
+/**
+ * struct stm_data - STM device description and callbacks
+ * @name:		device name
+ * @stm:		internal structure, only used by stm class code
+ * @sw_start:		first STP master available to software
+ * @sw_end:		last STP master available to software
+ * @sw_nchannels:	number of STP channels per master
+ * @sw_mmiosz:		size of one channel's IO space, for mmap, optional
+ * @packet:		callback that sends an STP packet
+ * @mmio_addr:		mmap callback, optional
+ * @link:		called when a new stm_source gets linked to us, optional
+ * @unlink:		likewise for unlinking, again optional
+ * @set_options:	set device-specific options on a channel
+ *
+ * Fill out this structure before calling stm_register_device() to create
+ * an STM device and stm_unregister_device() to destroy it. It will also be
+ * passed back to @packet(), @mmio_addr(), @link(), @unlink() and @set_options()
+ * callbacks.
+ *
+ * Normally, an STM device will have a range of masters available to software
+ * and the rest being statically assigned to various hardware trace sources.
+ * The former is defined by the the range [@sw_start..@sw_end] of the device
+ * description. That is, the lowest master that can be allocated to software
+ * writers is @sw_start and data from this writer will appear is @sw_start
+ * master in the STP stream.
+ */
+struct stm_data {
+	const char		*name;
+	struct stm_device	*stm;
+	unsigned int		sw_start;
+	unsigned int		sw_end;
+	unsigned int		sw_nchannels;
+	unsigned int		sw_mmiosz;
+	ssize_t			(*packet)(struct stm_data *, unsigned int,
+					  unsigned int, unsigned int,
+					  unsigned int, unsigned int,
+					  const unsigned char *);
+	phys_addr_t		(*mmio_addr)(struct stm_data *, unsigned int,
+					     unsigned int, unsigned int);
+	int			(*link)(struct stm_data *, unsigned int,
+					unsigned int);
+	void			(*unlink)(struct stm_data *, unsigned int,
+					  unsigned int);
+	long			(*set_options)(struct stm_data *, unsigned int,
+					       unsigned int, unsigned int,
+					       unsigned long);
+};
+
+int stm_register_device(struct device *parent, struct stm_data *stm_data,
+			struct module *owner);
+void stm_unregister_device(struct stm_data *stm_data);
+
+struct stm_source_device;
+
+/**
+ * struct stm_source_data - STM source device description and callbacks
+ * @name:	device name, will be used for policy lookup
+ * @src:	internal structure, only used by stm class code
+ * @nr_chans:	number of channels to allocate
+ * @link:	called when this source gets linked to an STM device
+ * @unlink:	called when this source is about to get unlinked from its STM
+ *
+ * Fill in this structure before calling stm_source_register_device() to
+ * register a source device. Also pass it to unregister and write calls.
+ */
+struct stm_source_data {
+	const char		*name;
+	struct stm_source_device *src;
+	unsigned int		percpu;
+	unsigned int		nr_chans;
+	int			(*link)(struct stm_source_data *data);
+	void			(*unlink)(struct stm_source_data *data);
+};
+
+int stm_source_register_device(struct device *parent,
+			       struct stm_source_data *data);
+void stm_source_unregister_device(struct stm_source_data *data);
+
+int stm_source_write(struct stm_source_data *data, unsigned int chan,
+		     const char *buf, size_t count);
+
+#endif /* _STM_H_ */
diff --git a/include/uapi/linux/stm.h b/include/uapi/linux/stm.h
new file mode 100644
index 0000000..626a8d3
--- /dev/null
+++ b/include/uapi/linux/stm.h
@@ -0,0 +1,50 @@
+/*
+ * System Trace Module (STM) userspace interfaces
+ * Copyright (c) 2014, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * STM class implements generic infrastructure for  System Trace Module devices
+ * as defined in MIPI STPv2 specification.
+ */
+
+#ifndef _UAPI_LINUX_STM_H
+#define _UAPI_LINUX_STM_H
+
+#include <linux/types.h>
+
+/**
+ * struct stp_policy_id - identification for the STP policy
+ * @size:	size of the structure including real id[] length
+ * @master:	assigned master
+ * @channel:	first assigned channel
+ * @width:	number of requested channels
+ * @id:		identification string
+ *
+ * User must calculate the total size of the structure and put it into
+ * @size field, fill out the @id and desired @width. In return, kernel
+ * fills out @master, @channel and @width.
+ */
+struct stp_policy_id {
+	__u32		size;
+	__u16		master;
+	__u16		channel;
+	__u16		width;
+	/* padding */
+	__u16		__reserved_0;
+	__u32		__reserved_1;
+	char		id[0];
+};
+
+#define STP_POLICY_ID_SET	_IOWR('%', 0, struct stp_policy_id)
+#define STP_POLICY_ID_GET	_IOR('%', 1, struct stp_policy_id)
+#define STP_SET_OPTIONS		_IOW('%', 2, __u64)
+
+#endif /* _UAPI_LINUX_STM_H */