diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-stm b/Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
new file mode 100644
index 000000000000..3ddb676831ab
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
@@ -0,0 +1,62 @@
+What:		/sys/bus/coresight/devices/<memory_map>.stm/enable_source
+Date:		February 2015
+KernelVersion:	3.20
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(RW) Enable/disable tracing on this specific trace macrocell.
+		Enabling the trace macrocell implies it has been configured
+		properly and a sink has been identidifed for it.  The path
+		of coresight components linking the source to the sink is
+		configured and managed automatically by the coresight framework.
+
+What:		/sys/bus/coresight/devices/<memory_map>.stm/entities
+Date:		February 2015
+KernelVersion:	3.20
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(RW) Controls which entities have been allowed to use the
+		stimulus ports, regarless of the channel they were assigned.
+		Entity definition can be found in
+		include/uapi/linux/coresight-stm32.h
+
+What:		/sys/bus/coresight/devices/<memory_map>.stm/hwevent_enable
+Date:		February 2015
+KernelVersion:	3.20
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(RW) Provides access to the HW event enable register, used in
+		conjunction with HW event bank select register.
+
+What:		/sys/bus/coresight/devices/<memory_map>.stm/hwevent_select
+Date:		February 2015
+KernelVersion:	3.20
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(RW) Gives access to the HW event block select register
+		(STMHEBSR) in order to configure up to 256 channels.  Used in
+		conjunction with "hwevent_enable" register as described above.
+
+What:		/sys/bus/coresight/devices/<memory_map>.stm/port_enable
+Date:		February 2015
+KernelVersion:	3.20
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(RW) Provides access to the stimlus port enable register
+		(STMSPER).  Used in conjunction with "port_select" described
+		below.
+
+What:		/sys/bus/coresight/devices/<memory_map>.stm/port_select
+Date:		February 2015
+KernelVersion:	3.20
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(RW) Used to determine which bank of stimulus port bit in
+		register STMSPER (see above) apply to.
+
+What:		/sys/bus/coresight/devices/<memory_map>.stm/status
+Date:		February 2015
+KernelVersion:	3.20
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(R) List various control and status registers.  The specific
+		layout and content is driver specific.
+
+What:		/sys/bus/coresight/devices/<memory_map>.stm/traceid
+Date:		February 2015
+KernelVersion:	3.20
+Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
+Description:	(RW) Holds the trace ID that will appear in the trace stream
+		coming from this trace entity.
diff --git a/Documentation/trace/coresight.txt b/Documentation/trace/coresight.txt
index 02361552a3ea..a041477698d9 100644
--- a/Documentation/trace/coresight.txt
+++ b/Documentation/trace/coresight.txt
@@ -190,8 +190,8 @@ expected to be accessed and controlled using those entries.
 Last but not least, "struct module *owner" is expected to be set to reflect
 the information carried in "THIS_MODULE".
 
-How to use
-----------
+How to use the tracer modules
+-----------------------------
 
 Before trace collection can start, a coresight sink needs to be identify.
 There is no limit on the amount of sinks (nor sources) that can be enabled at
@@ -297,3 +297,87 @@ Info                                    Tracing enabled
 Instruction     13570831        0x8026B584      E28DD00C        false   ADD      sp,sp,#0xc
 Instruction     0       0x8026B588      E8BD8000        true    LDM      sp!,{pc}
 Timestamp                                       Timestamp: 17107041535
+
+How to use the STM module
+-------------------------
+
+Using the System Trace Macrocell module is the same as the tracers - the only
+difference is that components (entities) are driving the trace capture rather
+than the program flow through the code.
+
+As with any other CoreSight component specifics about the STM tracer can be
+found in sysfs, with more information on each entry being found in [1]:
+
+root@genericarmv8:~# ls /sys/bus/coresight/devices/20100000.stm
+enable_source   hwevent_select  power           traceid
+entities        port_enable     status          uevent
+hwevent_enable  port_select     subsystem
+root@genericarmv8:~#
+
+Like any other source a sink needs to be identified and the STM enabled before
+being used:
+
+root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/20010000.etf/enable_sink
+root@genericarmv8:~# echo 1 > /sys/bus/coresight/devices/20100000.stm/enable_source
+
+From there user space applications can request and use channels using the devfs
+interface provided for that purpose:
+
+root@genericarmv8:~# ls -l /dev/20100000.stm
+crw-------    1 root     root       10,  61 Jan  3 18:11 /dev/20100000.stm
+root@genericarmv8:~#
+
+The following sample program provides an example of the supported operations:
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <string.h>
+#include <linux/coresight-stm.h>
+
+#define BUFSIZE	20
+
+int main(int argc, char *argv[])
+{
+	int fd, n;
+	unsigned long options;
+	char buf[BUFSIZE];
+	char data[BUFSIZE] = "this is a test";
+
+	fd = open (argv[1], O_RDWR, 0);
+
+	if (n == -1) {
+		printf("can't open %s\n", argv[1]);
+		return 0;
+	}
+
+	n = read(fd, buf, BUFSIZE);
+	printf("channel_id: %d\n", atoi(buf));
+
+	options = STM_OPTION_TIMESTAMPED;
+	ioctl(fd, STM_IOCTL_SET_OPTIONS, &options);
+	options = 0;
+	ioctl(fd, STM_IOCTL_GET_OPTIONS, &options);
+	printf("options: 0x%x\n", options);
+
+	write(fd, data, strlen(data));
+
+	close(fd);
+
+	return 0;
+}
+
+When opening the devfs entry the first available channel is reserved for the
+requesting application.  That channel will remain the same until close() is
+called where it will go back to the channel pool.  From there calling open()
+again may or may _not_ yield the same channel number.
+
+From user space applications can determine what channel they've been given by
+issueing a read() on the file descriptor returned by open().  An ioctl() call is
+provided to set the channel options and the write() method will inject logging
+information in the channel.  There is no limit on the amount of channels an
+application can reserve, granted they use a different file descriptor for each
+one.
+
+If no more channels are available value of returned channel ID is '-1'.
+
+[1]. Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
diff --git a/drivers/coresight/Kconfig b/drivers/coresight/Kconfig
index fc1f1ae7a49d..08806cc7d737 100644
--- a/drivers/coresight/Kconfig
+++ b/drivers/coresight/Kconfig
@@ -58,4 +58,14 @@ config CORESIGHT_SOURCE_ETM3X
 	  which allows tracing the instructions that a processor is executing
 	  This is primarily useful for instruction level tracing.  Depending
 	  the ETM version data tracing may also be available.
+
+config CORESIGHT_STM
+	bool "CoreSight System Trace Macrocell driver"
+	depends on (ARM && !(CPU_32v4 || CPU_32v4T)) || ARM64 || (64BIT && COMPILE_TEST)
+	select CORESIGHT_LINKS_AND_SINKS
+	help
+	  This driver provides support for hardware assisted software
+	  instrumentation based tracing. This is primarily used for
+	  logging useful software events or data coming from various entities
+	  in the system, possibly running different OSs
 endif
diff --git a/drivers/coresight/Makefile b/drivers/coresight/Makefile
index 4b4bec890ef5..7005b48a33ed 100644
--- a/drivers/coresight/Makefile
+++ b/drivers/coresight/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_CORESIGHT_SINK_ETBV10) += coresight-etb10.o
 obj-$(CONFIG_CORESIGHT_LINKS_AND_SINKS) += coresight-funnel.o \
 					   coresight-replicator.o
 obj-$(CONFIG_CORESIGHT_SOURCE_ETM3X) += coresight-etm3x.o coresight-etm-cp14.o
+obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
diff --git a/drivers/coresight/coresight-stm.c b/drivers/coresight/coresight-stm.c
new file mode 100644
index 000000000000..e59b0fe01d87
--- /dev/null
+++ b/drivers/coresight/coresight-stm.c
@@ -0,0 +1,1090 @@
+/* Copyright (c) 2014-2015, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/clk.h>
+#include <linux/bitmap.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/coresight.h>
+#include <linux/coresight-stm.h>
+#include <linux/amba/bus.h>
+#include <asm/unaligned.h>
+
+#include "coresight-priv.h"
+
+#define STMDMASTARTR			0xc04
+#define STMDMASTOPR			0xc08
+#define STMDMASTATR			0xc0c
+#define STMDMACTLR			0xc10
+#define STMDMAIDR			0xcfc
+#define STMHEER				0xd00
+#define STMHETER			0xd20
+#define STMHEBSR			0xd60
+#define STMHEMCR			0xd64
+#define STMHEMASTR			0xdf4
+#define STMHEFEAT1R			0xdf8
+#define STMHEIDR			0xdfc
+#define STMSPER				0xe00
+#define STMSPTER			0xe20
+#define STMPRIVMASKR			0xe40
+#define STMSPSCR			0xe60
+#define STMSPMSCR			0xe64
+#define STMSPOVERRIDER			0xe68
+#define STMSPMOVERRIDER			0xe6c
+#define STMSPTRIGCSR			0xe70
+#define STMTCSR				0xe80
+#define STMTSSTIMR			0xe84
+#define STMTSFREQR			0xe8c
+#define STMSYNCR			0xe90
+#define STMAUXCR			0xe94
+#define STMSPFEAT1R			0xea0
+#define STMSPFEAT2R			0xea4
+#define STMSPFEAT3R			0xea8
+#define STMITTRIGGER			0xee8
+#define STMITATBDATA0			0xeec
+#define STMITATBCTR2			0xef0
+#define STMITATBID			0xef4
+#define STMITATBCTR0			0xef8
+
+#define STM_32_CHANNEL			32
+#define BYTES_PER_CHANNEL		256
+#define STM_TRACE_BUF_SIZE		4096
+
+/* Register bit definition */
+#define STMTCSR_BUSY_BIT		23
+
+enum stm_pkt_type {
+	STM_PKT_TYPE_DATA	= 0x98,
+	STM_PKT_TYPE_FLAG	= 0xE8,
+	STM_PKT_TYPE_TRIG	= 0xF8,
+};
+
+enum {
+	STM_OPTION_MARKED	= 0x10,
+};
+
+#define stm_channel_addr(drvdata, ch)	(drvdata->chs.base +	\
+					(ch * BYTES_PER_CHANNEL))
+#define stm_channel_off(type, opts)	(type & ~opts)
+
+#ifndef CONFIG_64BIT
+static inline void __raw_writeq(u64 val, volatile void __iomem *addr)
+{
+	asm volatile("strd %1, %0"
+		     : "+Qo" (*(volatile u64 __force *)addr)
+		     : "r" (val));
+}
+
+static inline u64 __raw_readq(const volatile void __iomem *addr)
+{
+	u64 val;
+
+	asm volatile("ldrd %1, %0"
+		     : "+Qo" (*(volatile u64 __force *)addr),
+		       "=r" (val));
+	return val;
+}
+
+#undef readq_relaxed
+#define readq_relaxed(c) ({ u64 __r = le64_to_cpu((__force __le64) \
+					__raw_readq(c)); __r; })
+#undef writeq_relaxed
+#define writeq_relaxed(v, c)	__raw_writeq((__force u64) cpu_to_le64(v), c)
+#endif
+
+static int boot_nr_channel;
+
+module_param_named(
+	boot_nr_channel, boot_nr_channel, int, S_IRUGO
+);
+
+/**
+ * struct channel_space - central management entity for extended ports
+ * @base:		memory mapped base address where channels start.
+ * @bitmap:		tally of which channel is being used.
+ */
+struct channel_space {
+	void __iomem		*base;
+	unsigned long		*bitmap;
+};
+
+/**
+ * struct stm_node - aggregation of channel information for userspace access
+ * @channel_id:		the channel number associated to this file descriptor.
+ * @options:		options for this channel - none, timestamped,
+i			guaranteed.
+ * @drvdata:		STM driver specifics.
+ */
+struct stm_node {
+	int			channel_id;
+	u32			options;
+	struct stm_drvdata	*drvdata;
+};
+
+/**
+ * struct stm_drvdata - specifics associated to an STM component
+ * @ base:		memory mapped base address for this component.
+ * @dev:		the device entity associated to this component.
+ * @csdev:		component vitals needed by the framework.
+ * @miscdev:		specifics to handle "/dev/xyz.stm" entry.
+ * @clk:		the clock this component is associated to.
+ * @spinlock:		only one at a time pls.
+ * @chs:		the channels accociated to this STM.
+ * @enable:		this STM is being used.
+ * @entities:		set of entities allowed to access the STM ports.
+ * @traceid:		value of the current ID for this component.
+ * @write_64bit:	whether this STM supports 64 bit access.
+ * @stmsper:		settings for register STMSPER.
+ * @stmspscr:		settings for register STMSPSCR.
+ * @numsp:		the total number of stimulus port support by this STM.
+ * @stmheer:		settings for register STMHEER.
+ * @stmheter:		settings for register STMHETER.
+ * @stmhebsr:		settings for register STMHEBSR.
+ */
+struct stm_drvdata {
+	void __iomem		*base;
+	struct device		*dev;
+	struct coresight_device	*csdev;
+	struct miscdevice	miscdev;
+	struct clk		*clk;
+	spinlock_t		spinlock;
+	struct channel_space	chs;
+	bool			enable;
+	DECLARE_BITMAP(entities, STM_ENTITY_MAX);
+	u8			traceid;
+	u32			write_64bit;
+	u32			stmsper;
+	u32			stmspscr;
+	u32			numsp;
+	u32			stmheer;
+	u32			stmheter;
+	u32			stmhebsr;
+};
+
+static struct stm_drvdata *stmdrvdata;
+
+static void stm_hwevent_enable_hw(struct stm_drvdata *drvdata)
+{
+	CS_UNLOCK(drvdata->base);
+
+	writel_relaxed(drvdata->stmhebsr, drvdata->base + STMHEBSR);
+	writel_relaxed(drvdata->stmheter, drvdata->base + STMHETER);
+	writel_relaxed(drvdata->stmheer, drvdata->base + STMHEER);
+	writel_relaxed(0x01 |	/* Enable HW event tracing */
+		       0x04,	/* Error detection on event tracing */
+		       drvdata->base + STMHEMCR);
+
+	CS_LOCK(drvdata->base);
+}
+
+static void stm_port_enable_hw(struct stm_drvdata *drvdata)
+{
+	CS_UNLOCK(drvdata->base);
+	/* ATB trigger enable on direct writes to TRIG locations */
+	writel_relaxed(0x10,
+		       drvdata->base + STMSPTRIGCSR);
+	writel_relaxed(drvdata->stmspscr, drvdata->base + STMSPSCR);
+	writel_relaxed(drvdata->stmsper, drvdata->base + STMSPER);
+
+	CS_LOCK(drvdata->base);
+}
+
+static void stm_enable_hw(struct stm_drvdata *drvdata)
+{
+	if (drvdata->stmheer)
+		stm_hwevent_enable_hw(drvdata);
+
+	stm_port_enable_hw(drvdata);
+
+	CS_UNLOCK(drvdata->base);
+
+	/* 4096 byte between synchronisation packets */
+	writel_relaxed(0xFFF, drvdata->base + STMSYNCR);
+	writel_relaxed((drvdata->traceid << 16 | /* trace id */
+			0x02 |			 /* timestamp enable */
+			0x01),			 /* global STM enable */
+			drvdata->base + STMTCSR);
+
+	CS_LOCK(drvdata->base);
+}
+
+static int stm_enable(struct coresight_device *csdev)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+	int ret;
+
+	ret = clk_prepare_enable(drvdata->clk);
+	if (ret)
+		return ret;
+
+	spin_lock(&drvdata->spinlock);
+	stm_enable_hw(drvdata);
+	drvdata->enable = true;
+	spin_unlock(&drvdata->spinlock);
+
+	dev_info(drvdata->dev, "STM tracing enabled\n");
+	return 0;
+}
+
+static void stm_hwevent_disable_hw(struct stm_drvdata *drvdata)
+{
+	CS_UNLOCK(drvdata->base);
+
+	writel_relaxed(0x0, drvdata->base + STMHEMCR);
+	writel_relaxed(0x0, drvdata->base + STMHEER);
+	writel_relaxed(0x0, drvdata->base + STMHETER);
+
+	CS_LOCK(drvdata->base);
+}
+
+static void stm_port_disable_hw(struct stm_drvdata *drvdata)
+{
+	CS_UNLOCK(drvdata->base);
+
+	writel_relaxed(0x0, drvdata->base + STMSPER);
+	writel_relaxed(0x0, drvdata->base + STMSPTRIGCSR);
+
+	CS_LOCK(drvdata->base);
+}
+
+static void stm_disable_hw(struct stm_drvdata *drvdata)
+{
+	u32 val;
+
+	CS_UNLOCK(drvdata->base);
+
+	val = readl_relaxed(drvdata->base + STMTCSR);
+	val &= ~0x1; /* clear global STM enable [0] */
+	writel_relaxed(val, drvdata->base + STMTCSR);
+
+	CS_LOCK(drvdata->base);
+
+	stm_port_disable_hw(drvdata);
+	if (drvdata->stmheer)
+		stm_hwevent_disable_hw(drvdata);
+}
+
+static void stm_disable(struct coresight_device *csdev)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	spin_lock(&drvdata->spinlock);
+	stm_disable_hw(drvdata);
+	drvdata->enable = false;
+	spin_unlock(&drvdata->spinlock);
+
+	/* Wait until the engine has completely stopped */
+	coresight_timeout(drvdata, STMTCSR, STMTCSR_BUSY_BIT, 0);
+
+	clk_disable_unprepare(drvdata->clk);
+
+	dev_info(drvdata->dev, "STM tracing disabled\n");
+}
+
+static int stm_trace_id(struct coresight_device *csdev)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
+
+	return drvdata->traceid;
+}
+
+static const struct coresight_ops_source stm_source_ops = {
+	.trace_id	= stm_trace_id,
+	.enable		= stm_enable,
+	.disable	= stm_disable,
+};
+
+static const struct coresight_ops stm_cs_ops = {
+	.source_ops	= &stm_source_ops,
+};
+
+static int stm_channel_alloc(u32 off)
+{
+	struct stm_drvdata *drvdata = stmdrvdata;
+	int ch = -1;
+
+	do {
+		ch = find_next_zero_bit(drvdata->chs.bitmap,
+					drvdata->numsp, off);
+	} while ((ch < drvdata->numsp) &&
+		 test_and_set_bit(ch, drvdata->chs.bitmap));
+
+	return ch;
+}
+
+static void stm_channel_free(u32 ch)
+{
+	struct stm_drvdata *drvdata = stmdrvdata;
+
+	clear_bit(ch, drvdata->chs.bitmap);
+}
+
+static int stm_send_64bit(void *addr, const void *data, u32 size)
+{
+	u64 prepad = 0;
+	u64 postpad = 0;
+	char *pad;
+	u8 off, endoff;
+	u32 len = size;
+
+	off = (unsigned long)data & 0x7;
+
+	if (off) {
+		endoff = 8 - off;
+		pad = (char *)&prepad;
+		pad += off;
+
+		while (endoff && size) {
+			*pad++ = *(char *)data++;
+			endoff--;
+			size--;
+		}
+		writeq_relaxed(prepad, addr);
+	}
+
+	/* now we are 64bit aligned */
+	while (size >= 8) {
+		writeq_relaxed(*(u64 *)data, addr);
+		data += 8;
+		size -= 8;
+	}
+
+	endoff = 0;
+
+	if (size) {
+		endoff = 8 - (u8)size;
+		pad = (char *)&postpad;
+
+		while (size) {
+			*pad++ = *(char *)data++;
+			size--;
+		}
+		writeq_relaxed(postpad, addr);
+	}
+
+	return len + off + endoff;
+}
+
+static int stm_trace_data_64bit(unsigned long ch_addr, u32 options,
+				const void *data, u32 size)
+{
+	void *addr;
+
+	options &= ~STM_OPTION_TIMESTAMPED;
+	addr = (void *)(ch_addr | stm_channel_off(STM_PKT_TYPE_DATA, options));
+
+	return stm_send_64bit(addr, data, size);
+}
+
+static int stm_send(void *addr, const void *data, u32 size)
+{
+	u32 len = size;
+
+	if (((unsigned long)data & 0x1) && (size >= 1)) {
+		writeb_relaxed(*(u8 *)data, addr);
+		data++;
+		size--;
+	}
+	if (((unsigned long)data & 0x2) && (size >= 2)) {
+		writew_relaxed(*(u16 *)data, addr);
+		data += 2;
+		size -= 2;
+	}
+
+	/* now we are 32bit aligned */
+	while (size >= 4) {
+		writel_relaxed(*(u32 *)data, addr);
+		data += 4;
+		size -= 4;
+	}
+
+	if (size >= 2) {
+		writew_relaxed(*(u16 *)data, addr);
+		data += 2;
+		size -= 2;
+	}
+	if (size >= 1) {
+		writeb_relaxed(*(u8 *)data, addr);
+		data++;
+		size--;
+	}
+
+	return len;
+}
+
+static int stm_trace_data(unsigned long ch_addr, u32 options,
+			  const void *data, u32 size)
+{
+	void *addr;
+
+	options &= ~STM_OPTION_TIMESTAMPED;
+	addr = (void *)(ch_addr | stm_channel_off(STM_PKT_TYPE_DATA, options));
+
+	return stm_send(addr, data, size);
+}
+
+static inline int stm_trace_hw(u32 options, u32 channel, u8 entity_id,
+			       const void *data, u32 size)
+{
+	int len = 0;
+	unsigned long ch_addr;
+	struct stm_drvdata *drvdata = stmdrvdata;
+
+
+	/* get the channel address */
+	ch_addr = (unsigned long)stm_channel_addr(drvdata, channel);
+
+	if (drvdata->write_64bit)
+		len = stm_trace_data_64bit(ch_addr, options, data, size);
+	else
+		/* send the payload data */
+		len = stm_trace_data(ch_addr, options, data, size);
+
+	return len;
+}
+
+/**
+ * stm_trace - trace the binary or string data through STM
+ * @options: tracing options - guaranteed, timestamped, etc
+ * @entity_id: entity representing the trace data
+ * @data: pointer to binary or string data buffer
+ * @size: size of data to send
+ *
+ * Packetizes the data as the payload to an OST packet and sends it over STM
+ *
+ * CONTEXT:
+ * Can be called from any context.
+ *
+ * RETURNS:
+ * number of bytes transferred over STM
+ */
+int stm_trace(u32 options, int channel_id,
+	      u8 entity_id, const void *data, u32 size)
+{
+	struct stm_drvdata *drvdata = stmdrvdata;
+
+	if (channel_id < 0)
+		return 0;
+
+	/* we don't support sizes more than 24bits (0 to 23) */
+	if (!(drvdata && drvdata->enable &&
+	      test_bit(entity_id, drvdata->entities) && size &&
+	      (size < 0x1000000)))
+		return 0;
+
+	return stm_trace_hw(options, (u32)channel_id,
+			    entity_id, data, size);
+}
+EXPORT_SYMBOL(stm_trace);
+
+static int stm_open(struct inode *inode, struct file *file)
+{
+	struct stm_node *node;
+	struct stm_drvdata *drvdata = container_of(file->private_data,
+						   struct stm_drvdata, miscdev);
+
+	node = kmalloc(sizeof(struct stm_node), GFP_KERNEL);
+	if (!node)
+		return -ENOMEM;
+
+	node->drvdata = drvdata;
+	node->options = STM_OPTION_TIMESTAMPED;
+	node->channel_id = stm_channel_alloc(0);
+	if (node->channel_id < 0)
+		return -ENOMEM;
+
+	file->private_data = node;
+	return 0;
+}
+
+static int stm_release(struct inode *inode, struct file *file)
+{
+	struct stm_node *node = file->private_data;
+
+	/* we are done, free the channel */
+	if (node->channel_id >= 0)
+		stm_channel_free((u32)node->channel_id);
+	file->private_data = NULL;
+	kfree(node);
+	return 0;
+}
+
+static ssize_t stm_read(struct file *file, char __user *data,
+			size_t size, loff_t *ppos)
+{
+	char buf[20];
+	struct stm_node *node = file->private_data;
+
+	snprintf(buf, sizeof(buf), "%d", node->channel_id);
+	return simple_read_from_buffer(data, size, ppos,
+				       buf, strlen(buf));
+}
+
+static ssize_t stm_write(struct file *file, const char __user *data,
+			 size_t size, loff_t *ppos)
+{
+	char *buf;
+	struct stm_node *node = file->private_data;
+	struct stm_drvdata *drvdata = node->drvdata;
+
+	if (node->channel_id < 0)
+		return -EINVAL;
+
+	if (!drvdata->enable || !size)
+		return -EINVAL;
+
+	if (size > STM_TRACE_BUF_SIZE)
+		size = STM_TRACE_BUF_SIZE;
+
+	buf = kmalloc(size, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	if (copy_from_user(buf, data, size)) {
+		kfree(buf);
+		dev_dbg(drvdata->dev, "%s: copy_from_user failed\n", __func__);
+		return -EFAULT;
+	}
+
+	if (!test_bit(STM_ENTITY_TRACE_USPACE, drvdata->entities)) {
+		kfree(buf);
+		return size;
+	}
+
+	stm_trace_hw(node->options, (u32)node->channel_id,
+		     STM_ENTITY_TRACE_USPACE, buf, size);
+
+	kfree(buf);
+
+	return size;
+}
+
+static long stm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	u32 options;
+	struct stm_node *node = file->private_data;
+
+	switch (cmd) {
+	case STM_IOCTL_SET_OPTIONS:
+		if (copy_from_user(&options, (void __user *)arg, sizeof(u32)))
+			return -EFAULT;
+
+		options &= (STM_OPTION_TIMESTAMPED | STM_OPTION_GUARANTEED);
+		node->options = options;
+		break;
+	case STM_IOCTL_GET_OPTIONS:
+		options = node->options;
+		if (copy_to_user((void __user *)arg, &options, sizeof(options)))
+			return -EFAULT;
+		break;
+	default:
+		return -EINVAL;
+	};
+
+	return 0;
+}
+
+static const struct file_operations stm_fops = {
+	.owner		= THIS_MODULE,
+	.open		= stm_open,
+	.write		= stm_write,
+	.read		= stm_read,
+	.llseek		= no_llseek,
+	.unlocked_ioctl	= stm_ioctl,
+	.release	= stm_release,
+};
+
+static ssize_t hwevent_enable_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	unsigned long val = drvdata->stmheer;
+
+	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t hwevent_enable_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t size)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	unsigned long val;
+	int ret = 0;
+
+	ret = kstrtoul(buf, 16, &val);
+	if (ret)
+		return -EINVAL;
+
+	drvdata->stmheer = val;
+	/* HW event enable and trigger go hand in hand */
+	drvdata->stmheter = val;
+
+	return size;
+}
+static DEVICE_ATTR_RW(hwevent_enable);
+
+static ssize_t hwevent_select_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	unsigned long val = drvdata->stmhebsr;
+
+	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t hwevent_select_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t size)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	unsigned long val;
+	int ret = 0;
+
+	ret = kstrtoul(buf, 16, &val);
+	if (ret)
+		return -EINVAL;
+
+	drvdata->stmhebsr = val;
+
+	return size;
+}
+static DEVICE_ATTR_RW(hwevent_select);
+
+static ssize_t port_select_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	unsigned long val;
+
+	if (!drvdata->enable) {
+		val = drvdata->stmspscr;
+	} else {
+		spin_lock(&drvdata->spinlock);
+		val = readl_relaxed(drvdata->base + STMSPSCR);
+		spin_unlock(&drvdata->spinlock);
+	}
+
+	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t port_select_store(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf, size_t size)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	unsigned long val, stmsper;
+	int ret = 0;
+
+	ret = kstrtoul(buf, 16, &val);
+	if (ret)
+		return ret;
+
+	spin_lock(&drvdata->spinlock);
+	drvdata->stmspscr = val;
+
+	if (drvdata->enable) {
+		CS_UNLOCK(drvdata->base);
+		/* Process as per ARM's TRM recommendation */
+		stmsper = readl_relaxed(drvdata->base + STMSPER);
+		writel_relaxed(0x0, drvdata->base + STMSPER);
+		writel_relaxed(drvdata->stmspscr, drvdata->base + STMSPSCR);
+		writel_relaxed(stmsper, drvdata->base + STMSPER);
+		CS_LOCK(drvdata->base);
+	}
+	spin_unlock(&drvdata->spinlock);
+
+	return size;
+}
+static DEVICE_ATTR_RW(port_select);
+
+static ssize_t port_enable_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	unsigned long val;
+
+	if (!drvdata->enable) {
+		val = drvdata->stmsper;
+	} else {
+		spin_lock(&drvdata->spinlock);
+		val = readl_relaxed(drvdata->base + STMSPER);
+		spin_unlock(&drvdata->spinlock);
+	}
+
+	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t port_enable_store(struct device *dev,
+				 struct device_attribute *attr,
+				 const char *buf, size_t size)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	unsigned long val;
+	int ret = 0;
+
+	ret = kstrtoul(buf, 16, &val);
+	if (ret)
+		return ret;
+
+	spin_lock(&drvdata->spinlock);
+	drvdata->stmsper = val;
+
+	if (drvdata->enable) {
+		CS_UNLOCK(drvdata->base);
+		writel_relaxed(drvdata->stmsper, drvdata->base + STMSPER);
+		CS_LOCK(drvdata->base);
+	}
+	spin_unlock(&drvdata->spinlock);
+
+	return size;
+}
+static DEVICE_ATTR_RW(port_enable);
+
+static ssize_t entities_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	ssize_t len;
+
+	len = bitmap_scnprintf(buf, PAGE_SIZE, drvdata->entities,
+			       STM_ENTITY_MAX);
+
+	if (PAGE_SIZE - len < 2)
+		len = -EINVAL;
+	else
+		len += scnprintf(buf + len, 2, "\n");
+
+	return len;
+}
+
+static ssize_t entities_store(struct device *dev,
+			      struct device_attribute *attr,
+			      const char *buf, size_t size)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	unsigned long val1, val2;
+
+	if (sscanf(buf, "%lx %lx", &val1, &val2) != 2)
+		return -EINVAL;
+
+	if (val1 >= STM_ENTITY_MAX)
+		return -EINVAL;
+
+	if (val2)
+		__set_bit(val1, drvdata->entities);
+	else
+		__clear_bit(val1, drvdata->entities);
+
+	return size;
+}
+static DEVICE_ATTR_RW(entities);
+
+static ssize_t status_show(struct device *dev,
+			   struct device_attribute *attr, char *buf)
+{
+	int ret;
+	unsigned long flags;
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+	ret = clk_prepare_enable(drvdata->clk);
+	if (ret)
+		return ret;
+
+	spin_lock_irqsave(&drvdata->spinlock, flags);
+
+	CS_UNLOCK(drvdata->base);
+	ret = sprintf(buf,
+		      "STMTCSR:\t0x%08x\n"
+		      "STMTSFREQR:\t0x%08x\n"
+		      "STMTSYNCR:\t0x%08x\n"
+		      "STMSPER:\t0x%08x\n"
+		      "STMSPTER:\t0x%08x\n"
+		      "STMPRIVMASKR:\t0x%08x\n"
+		      "STMSPSCR:\t0x%08x\n"
+		      "STMSPMSCR:\t0x%08x\n"
+		      "STMFEAT1R:\t0x%08x\n"
+		      "STMFEAT2R:\t0x%08x\n"
+		      "STMFEAT3R:\t0x%08x\n"
+		      "STMDEVID:\t0x%08x\n",
+		      readl_relaxed(drvdata->base + STMTCSR),
+		      readl_relaxed(drvdata->base + STMTSFREQR),
+		      readl_relaxed(drvdata->base + STMSYNCR),
+		      readl_relaxed(drvdata->base + STMSPER),
+		      readl_relaxed(drvdata->base + STMSPTER),
+		      readl_relaxed(drvdata->base + STMPRIVMASKR),
+		      readl_relaxed(drvdata->base + STMSPSCR),
+		      readl_relaxed(drvdata->base + STMSPMSCR),
+		      readl_relaxed(drvdata->base + STMSPFEAT1R),
+		      readl_relaxed(drvdata->base + STMSPFEAT2R),
+		      readl_relaxed(drvdata->base + STMSPFEAT3R),
+		      readl_relaxed(drvdata->base + CORESIGHT_DEVID));
+
+	CS_LOCK(drvdata->base);
+	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+	clk_disable_unprepare(drvdata->clk);
+
+	return ret;
+}
+static DEVICE_ATTR_RO(status);
+
+static ssize_t traceid_show(struct device *dev,
+			    struct device_attribute *attr, char *buf)
+{
+	unsigned long val;
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+	val = drvdata->traceid;
+	return sprintf(buf, "%#lx\n", val);
+}
+
+static ssize_t traceid_store(struct device *dev,
+			     struct device_attribute *attr,
+			     const char *buf, size_t size)
+{
+	int ret;
+	unsigned long val;
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+	ret = kstrtoul(buf, 16, &val);
+	if (ret)
+		return ret;
+
+	/* traceid field is 7bit wide on STM32 */
+	drvdata->traceid = val & 0x7f;
+	return size;
+}
+static DEVICE_ATTR_RW(traceid);
+
+static struct attribute *coresight_stm_attrs[] = {
+	&dev_attr_hwevent_enable.attr,
+	&dev_attr_hwevent_select.attr,
+	&dev_attr_port_enable.attr,
+	&dev_attr_port_select.attr,
+	&dev_attr_entities.attr,
+	&dev_attr_status.attr,
+	&dev_attr_traceid.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(coresight_stm);
+
+static int stm_get_resource_byname(struct device_node *np,
+				   char *ch_base, struct resource *res)
+{
+	const char *name = NULL;
+	int index = 0, found = 0;
+
+	while (!of_property_read_string_index(np, "reg-names", index, &name)) {
+		if (strcmp(ch_base, name)) {
+			index++;
+			continue;
+		}
+
+		/* We have a match and @index is where it's at */
+		found = 1;
+		break;
+	}
+
+	if (!found)
+		return -EINVAL;
+
+	return of_address_to_resource(np, index, res);
+}
+
+static u32 stm_fundamental_data_size(struct stm_drvdata *drvdata)
+{
+	u32 stmspfeat2r;
+
+	stmspfeat2r = readl_relaxed(drvdata->base + STMSPFEAT2R);
+	return BMVAL(stmspfeat2r, 12, 15);
+}
+
+static u32 stm_num_stimulus_port(struct stm_drvdata *drvdata)
+{
+	u32 numsp;
+
+	numsp = readl_relaxed(drvdata->base + CORESIGHT_DEVID);
+	/*
+	 * NUMPS in STMDEVID is 17 bit long and if equal to 0x0,
+	 * 32 stimulus ports are supported.
+	 */
+	numsp &= 0x1ffff;
+	if (!numsp)
+		numsp = STM_32_CHANNEL;
+	return numsp;
+}
+
+static void stm_init_default_data(struct stm_drvdata *drvdata)
+{
+	/* Don't use port selection */
+	drvdata->stmspscr = 0x0;
+	/*
+	 * Enable all channel regardless of their number.  When port
+	 * selection isn't used (see above) STMSPER applies to all
+	 * 32 channel group available, hence setting all 32 bits to 1
+	 */
+	drvdata->stmsper = ~0x0;
+
+	/*
+	 * Select arbitrary value to start with.  If there is a conflict
+	 * with other tracers the framework will deal with it.
+	 */
+	drvdata->traceid = 0x20;
+
+	bitmap_zero(drvdata->entities, STM_ENTITY_MAX);
+}
+
+static int stm_probe(struct amba_device *adev, const struct amba_id *id)
+{
+	int ret;
+	void __iomem *base;
+	unsigned long *bitmap;
+	struct device *dev = &adev->dev;
+	struct coresight_platform_data *pdata = NULL;
+	struct stm_drvdata *drvdata;
+	struct resource *res = &adev->res;
+	struct resource ch_res;
+	size_t res_size, bitmap_size;
+	struct coresight_desc *desc;
+	struct device_node *np = adev->dev.of_node;
+
+	if (np) {
+		pdata = of_get_coresight_platform_data(dev, np);
+		if (IS_ERR(pdata))
+			return PTR_ERR(pdata);
+		adev->dev.platform_data = pdata;
+	}
+	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
+
+	/* Store the driver data pointer for use in exported functions */
+	stmdrvdata = drvdata;
+	drvdata->dev = &adev->dev;
+	dev_set_drvdata(dev, drvdata);
+
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+	drvdata->base = base;
+
+	ret = stm_get_resource_byname(np, "stm-channel-base", &ch_res);
+	if (ret)
+		return ret;
+
+	base = devm_ioremap_resource(dev, &ch_res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+	drvdata->chs.base = base;
+
+	ret = clk_prepare_enable(drvdata->clk);
+	if (ret)
+		return ret;
+
+	drvdata->write_64bit = stm_fundamental_data_size(drvdata);
+
+	if (boot_nr_channel) {
+		drvdata->numsp = boot_nr_channel;
+		res_size = min((resource_size_t)(boot_nr_channel *
+				  BYTES_PER_CHANNEL), resource_size(res));
+		bitmap_size = boot_nr_channel * sizeof(long);
+	} else {
+		drvdata->numsp = stm_num_stimulus_port(drvdata);
+		res_size = min((resource_size_t)(drvdata->numsp *
+				 BYTES_PER_CHANNEL), resource_size(res));
+		bitmap_size = drvdata->numsp * sizeof(long);
+	}
+
+	clk_disable_unprepare(drvdata->clk);
+
+	bitmap = devm_kzalloc(dev, bitmap_size, GFP_KERNEL);
+	if (!bitmap)
+		return -ENOMEM;
+	drvdata->chs.bitmap = bitmap;
+
+	spin_lock_init(&drvdata->spinlock);
+
+	drvdata->clk = adev->pclk;
+
+	stm_init_default_data(drvdata);
+
+	desc = devm_kzalloc(dev, sizeof(*desc), GFP_KERNEL);
+	if (!desc)
+		return -ENOMEM;
+
+	desc->type = CORESIGHT_DEV_TYPE_SOURCE;
+	desc->subtype.source_subtype = CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE;
+	desc->ops = &stm_cs_ops;
+	desc->pdata = pdata;
+	desc->dev = dev;
+	desc->groups = coresight_stm_groups;
+	drvdata->csdev = coresight_register(desc);
+	if (IS_ERR(drvdata->csdev))
+		return PTR_ERR(drvdata->csdev);
+
+	drvdata->miscdev.name = pdata->name;
+	drvdata->miscdev.minor = MISC_DYNAMIC_MINOR;
+	drvdata->miscdev.fops = &stm_fops;
+	ret = misc_register(&drvdata->miscdev);
+	if (ret)
+		goto err;
+
+	dev_info(drvdata->dev, "STM initialized\n");
+
+	return 0;
+err:
+	coresight_unregister(drvdata->csdev);
+	return ret;
+}
+
+static int stm_remove(struct amba_device *adev)
+{
+	struct stm_drvdata *drvdata = amba_get_drvdata(adev);
+
+	misc_deregister(&drvdata->miscdev);
+	coresight_unregister(drvdata->csdev);
+	return 0;
+}
+
+static struct amba_id stm_ids[] = {
+	{
+		.id     = 0x0003b962,
+		.mask   = 0x0003ffff,
+	},
+	{ 0, 0},
+};
+
+static struct amba_driver stm_driver = {
+	.drv = {
+		.name   = "coresight-stm",
+		.owner	= THIS_MODULE,
+	},
+	.probe          = stm_probe,
+	.remove         = stm_remove,
+	.id_table	= stm_ids,
+};
+
+module_amba_driver(stm_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("CoreSight System Trace Macrocell driver");
diff --git a/include/linux/coresight-stm.h b/include/linux/coresight-stm.h
new file mode 100644
index 000000000000..98d57eb85adf
--- /dev/null
+++ b/include/linux/coresight-stm.h
@@ -0,0 +1,35 @@
+#ifndef __LINUX_CORESIGHT_STM_H_
+#define __LINUX_CORESIGHT_STM_H_
+
+#include <uapi/linux/coresight-stm.h>
+
+#define stm_log_inv(entity_id, ch_id, data, size)		\
+	stm_trace(STM_OPTION_NONE, ch_id, entity_id, data, size)
+
+#define stm_log_inv_ts(entity_id, ch_id, data, size)		\
+	stm_trace(STM_OPTION_TIMESTAMPED, ch_id, entity_id,	\
+		  data, size)
+
+#define stm_log_gtd(entity_id, ch_id, data, size)		\
+	stm_trace(STM_OPTION_GUARANTEED, ch_id, entity_id,	\
+		  data, size)
+
+#define stm_log_gtd_ts(entity_id, ch_id, data, size)		\
+	stm_trace(STM_OPTION_GUARANTEED | STM_OPTION_TIMESTAMPED,	\
+		  ch_id, entity_id, data, size)
+
+#define stm_log(entity_id, ch_id, data, size)				\
+	stm_log_inv_ts(entity_id, ch_id, data, size)
+
+#ifdef CONFIG_CORESIGHT_STM
+extern int stm_trace(u32 options, int channel_id,
+		     u8 entity_id, const void *data, u32 size);
+#else
+static inline int stm_trace(u32 options, int channel_id,
+			    u8 entity_id, const void *data, u32 size)
+{
+	return 0;
+}
+#endif
+
+#endif
diff --git a/include/uapi/linux/coresight-stm.h b/include/uapi/linux/coresight-stm.h
new file mode 100644
index 000000000000..d39231d50127
--- /dev/null
+++ b/include/uapi/linux/coresight-stm.h
@@ -0,0 +1,23 @@
+#ifndef __UAPI_CORESIGHT_STM_H_
+#define __UAPI_CORESIGHT_STM_H_
+
+enum {
+	STM_ENTITY_NONE			= 0x00,
+	STM_ENTITY_TRACE_PRINTK		= 0x01,
+	STM_ENTITY_TRACE_USPACE		= 0x02,
+	STM_ENTITY_MAX			= 0xFF,
+};
+
+enum {
+	STM_IOCTL_NONE			= 0x00,
+	STM_IOCTL_SET_OPTIONS		= 0x01,
+	STM_IOCTL_GET_OPTIONS		= 0x10,
+};
+
+enum {
+	STM_OPTION_NONE			= 0x0,
+	STM_OPTION_TIMESTAMPED		= 0x08,
+	STM_OPTION_GUARANTEED		= 0x80,
+};
+
+#endif
