[RFC 7/8] coresight: add CoreSight STM driver

[pratikp@codeaurora.org (pratikp at codeaurora.org)]

From: Pratik Patel <pratikp@codeaurora.org>

This driver manages CoreSight STM (System Trace Macrocell) and
provides apis and user interface to support software
instrumentation based tracing that takes advantage of the STM
hardware.

Signed-off-by: Pratik Patel <pratikp@codeaurora.org>
---
 drivers/coresight/Kconfig         |   19 +
 drivers/coresight/Makefile        |    1 +
 drivers/coresight/coresight-stm.c |  819 +++++++++++++++++++++++++++++++++++++
 include/linux/coresight-stm.h     |   51 +++
 4 files changed, 890 insertions(+), 0 deletions(-)
 create mode 100644 drivers/coresight/coresight-stm.c
 create mode 100644 include/linux/coresight-stm.h

diff --git a/drivers/coresight/Kconfig b/drivers/coresight/Kconfig
index 6905ef2..5a715e8 100644
--- a/drivers/coresight/Kconfig
+++ b/drivers/coresight/Kconfig
@@ -17,4 +17,23 @@ config CORESIGHT_LINKS_AND_SINKS
 	  responsible for transporting and collecting the trace data
 	  respectively.
 
+config CORESIGHT_SOURCE_STM
+	bool "CoreSight System Trace Macrocell driver"
+	select CORESIGHT_LINKS_AND_SINKS
+	help
+	  This driver provides support for hardware assisted software
+	  instrumentation based tracing. This is primarily useful for
+	  logging useful software events or data.
+
+config CORESIGHT_SOURCE_STM_DEFAULT_ENABLE
+	bool "Turn on CoreSight STM tracing by default"
+	depends on CORESIGHT_SOURCE_STM
+	help
+	  Turns on CoreSight STM tracing (hardware assisted software
+	  instrumentation based tracing) by default. Otherwise, tracing is
+	  disabled by default but can be enabled via sysfs.
+
+	  If unsure, say 'N' here to avoid potential power, performance and
+	  memory penalty.
+
 endif
diff --git a/drivers/coresight/Makefile b/drivers/coresight/Makefile
index b385e81..750aa7c 100644
--- a/drivers/coresight/Makefile
+++ b/drivers/coresight/Makefile
@@ -4,3 +4,4 @@
 obj-$(CONFIG_CORESIGHT) += coresight.o
 obj-$(CONFIG_OF) += of_coresight.o
 obj-$(CONFIG_CORESIGHT_LINKS_AND_SINKS) += coresight-tmc.o coresight-tpiu.o coresight-etb.o coresight-funnel.o coresight-replicator.o
+obj-$(CONFIG_CORESIGHT_SOURCE_STM) += coresight-stm.o
diff --git a/drivers/coresight/coresight-stm.c b/drivers/coresight/coresight-stm.c
new file mode 100644
index 0000000..69966ed
--- /dev/null
+++ b/drivers/coresight/coresight-stm.c
@@ -0,0 +1,819 @@
+/* Copyright (c) 2012, 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/platform_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_coresight.h>
+#include <linux/coresight.h>
+#include <linux/coresight-stm.h>
+#include <asm/unaligned.h>
+
+#include "coresight-priv.h"
+
+#define stm_writel(drvdata, val, off)	__raw_writel((val), drvdata->base + off)
+#define stm_readl(drvdata, off)		__raw_readl(drvdata->base + off)
+
+#define STM_LOCK(drvdata)						\
+do {									\
+	mb();								\
+	stm_writel(drvdata, 0x0, CORESIGHT_LAR);			\
+} while (0)
+#define STM_UNLOCK(drvdata)						\
+do {									\
+	stm_writel(drvdata, CORESIGHT_UNLOCK, CORESIGHT_LAR);		\
+	mb();								\
+} while (0)
+
+#define STMDMASTARTR			(0xC04)
+#define STMDMASTOPR			(0xC08)
+#define STMDMASTATR			(0xC0C)
+#define STMDMACTLR			(0xC10)
+#define STMDMAIDR			(0xCFC)
+#define STMHEER				(0xD00)
+#define STMHETER			(0xD20)
+#define STMHEMCR			(0xD64)
+#define STMHEMASTR			(0xDF4)
+#define STMHEFEAT1R			(0xDF8)
+#define STMHEIDR			(0xDFC)
+#define STMSPER				(0xE00)
+#define STMSPTER			(0xE20)
+#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 NR_STM_CHANNEL			(32)
+#define BYTES_PER_CHANNEL		(256)
+#define STM_TRACE_BUF_SIZE		(4096)
+#define STM_USERSPACE_HEADER_SIZE	(8)
+#define STM_USERSPACE_MAGIC1_VAL	(0xf0)
+#define STM_USERSPACE_MAGIC2_VAL	(0xf1)
+
+#define OST_START_TOKEN			(0x30)
+#define OST_VERSION			(0x1)
+
+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)
+
+#ifdef CONFIG_CORESIGHT_SOURCE_STM_DEFAULT_ENABLE
+static int boot_enable = 1;
+#else
+static int boot_enable;
+#endif
+
+module_param_named(
+	boot_enable, boot_enable, int, S_IRUGO
+);
+
+static int boot_nr_channel;
+
+module_param_named(
+	boot_nr_channel, boot_nr_channel, int, S_IRUGO
+);
+
+struct channel_space {
+	void __iomem		*base;
+	unsigned long		*bitmap;
+};
+
+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, OST_ENTITY_MAX);
+};
+
+static struct stm_drvdata *stmdrvdata;
+
+static int stm_hwevent_isenable(struct stm_drvdata *drvdata)
+{
+	int ret = 0;
+
+	spin_lock(&drvdata->spinlock);
+	if (drvdata->enable)
+		if (BVAL(stm_readl(drvdata, STMHEMCR), 0))
+			ret = stm_readl(drvdata, STMHEER) == 0 ? 0 : 1;
+	spin_unlock(&drvdata->spinlock);
+
+	return ret;
+}
+
+static void __stm_hwevent_enable(struct stm_drvdata *drvdata)
+{
+	STM_UNLOCK(drvdata);
+
+	/*
+	 * Program STMHETER to ensure TRIGOUTHETE (fed to CTI) is asserted
+	 * for HW events.
+	 */
+	stm_writel(drvdata, 0xFFFFFFFF, STMHETER);
+	stm_writel(drvdata, 0xFFFFFFFF, STMHEER);
+	stm_writel(drvdata, 0x5, STMHEMCR);
+
+	STM_LOCK(drvdata);
+}
+
+static int stm_hwevent_enable(struct stm_drvdata *drvdata)
+{
+	int ret = 0;
+
+	spin_lock(&drvdata->spinlock);
+	if (drvdata->enable)
+		__stm_hwevent_enable(drvdata);
+	else
+		ret = -EINVAL;
+	spin_unlock(&drvdata->spinlock);
+
+	return ret;
+}
+
+static int stm_port_isenable(struct stm_drvdata *drvdata)
+{
+	int ret = 0;
+
+	spin_lock(&drvdata->spinlock);
+	if (drvdata->enable)
+		ret = stm_readl(drvdata, STMSPER) == 0 ? 0 : 1;
+	spin_unlock(&drvdata->spinlock);
+
+	return ret;
+}
+
+static void __stm_port_enable(struct stm_drvdata *drvdata)
+{
+	STM_UNLOCK(drvdata);
+
+	stm_writel(drvdata, 0x10, STMSPTRIGCSR);
+	stm_writel(drvdata, 0xFFFFFFFF, STMSPER);
+
+	STM_LOCK(drvdata);
+}
+
+static int stm_port_enable(struct stm_drvdata *drvdata)
+{
+	int ret = 0;
+
+	spin_lock(&drvdata->spinlock);
+	if (drvdata->enable)
+		__stm_port_enable(drvdata);
+	else
+		ret = -EINVAL;
+	spin_unlock(&drvdata->spinlock);
+
+	return ret;
+}
+
+static void __stm_enable(struct stm_drvdata *drvdata)
+{
+	__stm_hwevent_enable(drvdata);
+	__stm_port_enable(drvdata);
+
+	STM_UNLOCK(drvdata);
+
+	stm_writel(drvdata, 0xFFF, STMSYNCR);
+	/* SYNCEN is read-only and HWTEN is not implemented */
+	stm_writel(drvdata, 0x100003, STMTCSR);
+
+	STM_LOCK(drvdata);
+}
+
+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(drvdata);
+	drvdata->enable = true;
+	spin_unlock(&drvdata->spinlock);
+
+	dev_info(drvdata->dev, "STM tracing enabled\n");
+	return 0;
+}
+
+static void __stm_hwevent_disable(struct stm_drvdata *drvdata)
+{
+	STM_UNLOCK(drvdata);
+
+	stm_writel(drvdata, 0x0, STMHEMCR);
+	stm_writel(drvdata, 0x0, STMHEER);
+	stm_writel(drvdata, 0x0, STMHETER);
+
+	STM_LOCK(drvdata);
+}
+
+static void stm_hwevent_disable(struct stm_drvdata *drvdata)
+{
+	spin_lock(&drvdata->spinlock);
+	if (drvdata->enable)
+		__stm_hwevent_disable(drvdata);
+	spin_unlock(&drvdata->spinlock);
+}
+
+static void __stm_port_disable(struct stm_drvdata *drvdata)
+{
+	STM_UNLOCK(drvdata);
+
+	stm_writel(drvdata, 0x0, STMSPER);
+	stm_writel(drvdata, 0x0, STMSPTRIGCSR);
+
+	STM_LOCK(drvdata);
+}
+
+static void stm_port_disable(struct stm_drvdata *drvdata)
+{
+	spin_lock(&drvdata->spinlock);
+	if (drvdata->enable)
+		__stm_port_disable(drvdata);
+	spin_unlock(&drvdata->spinlock);
+}
+
+static void __stm_disable(struct stm_drvdata *drvdata)
+{
+	STM_UNLOCK(drvdata);
+
+	stm_writel(drvdata, 0x100000, STMTCSR);
+
+	STM_LOCK(drvdata);
+
+	__stm_hwevent_disable(drvdata);
+	__stm_port_disable(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(drvdata);
+	drvdata->enable = false;
+	spin_unlock(&drvdata->spinlock);
+
+	/* Wait for 100ms so that pending data has been written to HW */
+	msleep(100);
+
+	clk_disable_unprepare(drvdata->clk);
+
+	dev_info(drvdata->dev, "STM tracing disabled\n");
+}
+
+static const struct coresight_ops_source stm_source_ops = {
+	.enable		= stm_enable,
+	.disable	= stm_disable,
+};
+
+static const struct coresight_ops stm_cs_ops = {
+	.source_ops	= &stm_source_ops,
+};
+
+static uint32_t stm_channel_alloc(uint32_t off)
+{
+	struct stm_drvdata *drvdata = stmdrvdata;
+	uint32_t ch;
+
+	do {
+		ch = find_next_zero_bit(drvdata->chs.bitmap,
+					NR_STM_CHANNEL, off);
+	} while ((ch < NR_STM_CHANNEL) &&
+		 test_and_set_bit(ch, drvdata->chs.bitmap));
+
+	return ch;
+}
+
+static void stm_channel_free(uint32_t ch)
+{
+	struct stm_drvdata *drvdata = stmdrvdata;
+
+	clear_bit(ch, drvdata->chs.bitmap);
+}
+
+static int stm_send(void *addr, const void *data, uint32_t size)
+{
+	uint64_t prepad = 0;
+	uint64_t postpad = 0;
+	char *pad;
+	uint8_t off, endoff;
+	uint32_t len = size;
+
+	/*
+	 * Only 64bit writes are supported. We rely on the compiler to
+	 * generate STRD instruction for the casted 64bit assignments.
+	 */
+
+	off = (unsigned long)data & 0x7;
+
+	if (off) {
+		endoff = 8 - off;
+		pad = (char *)&prepad;
+		pad += off;
+
+		while (endoff && size) {
+			*pad++ = *(char *)data++;
+			endoff--;
+			size--;
+		}
+		*(volatile uint64_t __force *)addr = prepad;
+	}
+
+	/* Now we are 64bit aligned */
+	while (size >= 8) {
+		*(volatile uint64_t __force *)addr = *(uint64_t *)data;
+		data += 8;
+		size -= 8;
+	}
+
+	if (size) {
+		pad = (char *)&postpad;
+
+		while (size) {
+			*pad++ = *(char *)data++;
+			size--;
+		}
+		*(volatile uint64_t __force *)addr = postpad;
+	}
+
+	return roundup(len + off, 8);
+}
+
+static int stm_trace_ost_header(unsigned long ch_addr, uint32_t options,
+				uint8_t entity_id, uint8_t proto_id,
+				const void *payload_data, uint32_t payload_size)
+{
+	void *addr;
+	uint8_t prepad_size;
+	uint64_t header;
+	char *hdr;
+
+	hdr = (char *)&header;
+
+	hdr[0] = OST_START_TOKEN;
+	hdr[1] = OST_VERSION;
+	hdr[2] = entity_id;
+	hdr[3] = proto_id;
+	prepad_size = (unsigned long)payload_data & 0x7;
+	*(uint32_t *)(hdr + 4) = (prepad_size << 24) | payload_size;
+
+	/* For 64bit writes, header is expected to be of the D32M, D32M */
+	options |= STM_OPTION_MARKED;
+	options &= ~STM_OPTION_TIMESTAMPED;
+	addr =  (void *)(ch_addr | stm_channel_off(STM_PKT_TYPE_DATA, options));
+
+	return stm_send(addr, &header, sizeof(header));
+}
+
+static int stm_trace_data(unsigned long ch_addr, uint32_t options,
+			  const void *data, uint32_t 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 int stm_trace_ost_tail(unsigned long ch_addr, uint32_t options)
+{
+	void *addr;
+	uint64_t tail = 0x0;
+
+	addr = (void *)(ch_addr | stm_channel_off(STM_PKT_TYPE_FLAG, options));
+
+	return stm_send(addr, &tail, sizeof(tail));
+}
+
+static inline int __stm_trace(uint32_t options, uint8_t entity_id,
+			      uint8_t proto_id, const void *data, uint32_t size)
+{
+	struct stm_drvdata *drvdata = stmdrvdata;
+	int len = 0;
+	uint32_t ch;
+	unsigned long ch_addr;
+
+	/* Allocate channel and get the channel address */
+	ch = stm_channel_alloc(0);
+	ch_addr = (unsigned long)stm_channel_addr(drvdata, ch);
+
+	/* Send the ost header */
+	len += stm_trace_ost_header(ch_addr, options, entity_id, proto_id, data,
+				    size);
+
+	/* Send the payload data */
+	len += stm_trace_data(ch_addr, options, data, size);
+
+	/* Send the ost tail */
+	len += stm_trace_ost_tail(ch_addr, options);
+
+	/* We are done, free the channel */
+	stm_channel_free(ch);
+
+	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
+ * @proto_id: protocol id to distinguish between different binary formats
+ * @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 transfered over STM
+ */
+int stm_trace(uint32_t options, uint8_t entity_id, uint8_t proto_id,
+			const void *data, uint32_t size)
+{
+	struct stm_drvdata *drvdata = stmdrvdata;
+
+	/* 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(options, entity_id, proto_id, data, size);
+}
+EXPORT_SYMBOL_GPL(stm_trace);
+
+static ssize_t stm_write(struct file *file, const char __user *data,
+			 size_t size, loff_t *ppos)
+{
+	struct stm_drvdata *drvdata = container_of(file->private_data,
+						   struct stm_drvdata, miscdev);
+	char *buf;
+	uint8_t entity_id, proto_id;
+	uint32_t options;
+
+	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 (size >= STM_USERSPACE_HEADER_SIZE &&
+	    buf[0] == STM_USERSPACE_MAGIC1_VAL &&
+	    buf[1] == STM_USERSPACE_MAGIC2_VAL) {
+
+		entity_id = buf[2];
+		proto_id = buf[3];
+		options = *(uint32_t *)(buf + 4);
+
+		if (!test_bit(entity_id, drvdata->entities) ||
+		    !(size - STM_USERSPACE_HEADER_SIZE)) {
+			kfree(buf);
+			return size;
+		}
+
+		__stm_trace(options, entity_id, proto_id,
+			    buf + STM_USERSPACE_HEADER_SIZE,
+			    size - STM_USERSPACE_HEADER_SIZE);
+	} else {
+		if (!test_bit(OST_ENTITY_DEV_NODE, drvdata->entities)) {
+			kfree(buf);
+			return size;
+		}
+
+		__stm_trace(STM_OPTION_TIMESTAMPED, OST_ENTITY_DEV_NODE, 0,
+			    buf, size);
+	}
+
+	kfree(buf);
+
+	return size;
+}
+
+static const struct file_operations stm_fops = {
+	.owner		= THIS_MODULE,
+	.open		= nonseekable_open,
+	.write		= stm_write,
+	.llseek		= no_llseek,
+};
+
+static ssize_t stm_show_hwevent_enable(struct device *dev,
+				       struct device_attribute *attr, char *buf)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	unsigned long val = stm_hwevent_isenable(drvdata);
+
+	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t stm_store_hwevent_enable(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;
+
+	if (sscanf(buf, "%lx", &val) != 1)
+		return -EINVAL;
+
+	if (val)
+		ret = stm_hwevent_enable(drvdata);
+	else
+		stm_hwevent_disable(drvdata);
+
+	if (ret)
+		return ret;
+	return size;
+}
+static DEVICE_ATTR(hwevent_enable, S_IRUGO | S_IWUSR, stm_show_hwevent_enable,
+		   stm_store_hwevent_enable);
+
+static ssize_t stm_show_port_enable(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct stm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+	unsigned long val = stm_port_isenable(drvdata);
+
+	return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
+}
+
+static ssize_t stm_store_port_enable(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;
+
+	if (sscanf(buf, "%lx", &val) != 1)
+		return -EINVAL;
+
+	if (val)
+		ret = stm_port_enable(drvdata);
+	else
+		stm_port_disable(drvdata);
+
+	if (ret)
+		return ret;
+	return size;
+}
+static DEVICE_ATTR(port_enable, S_IRUGO | S_IWUSR, stm_show_port_enable,
+		   stm_store_port_enable);
+
+static ssize_t stm_show_entities(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,
+			       OST_ENTITY_MAX);
+
+	if (PAGE_SIZE - len < 2)
+		len = -EINVAL;
+	else
+		len += scnprintf(buf + len, 2, "\n");
+
+	return len;
+}
+
+static ssize_t stm_store_entities(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 >= OST_ENTITY_MAX)
+		return -EINVAL;
+
+	if (val2)
+		__set_bit(val1, drvdata->entities);
+	else
+		__clear_bit(val1, drvdata->entities);
+
+	return size;
+}
+static DEVICE_ATTR(entities, S_IRUGO | S_IWUSR, stm_show_entities,
+		   stm_store_entities);
+
+static struct attribute *stm_attrs[] = {
+	&dev_attr_hwevent_enable.attr,
+	&dev_attr_port_enable.attr,
+	&dev_attr_entities.attr,
+	NULL,
+};
+
+static struct attribute_group stm_attr_grp = {
+	.attrs = stm_attrs,
+};
+
+static const struct attribute_group *stm_attr_grps[] = {
+	&stm_attr_grp,
+	NULL,
+};
+
+static int __devinit stm_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct device *dev = &pdev->dev;
+	struct coresight_platform_data *pdata;
+	struct stm_drvdata *drvdata;
+	struct resource *res;
+	size_t res_size, bitmap_size;
+	struct coresight_desc *desc;
+
+	if (pdev->dev.of_node) {
+		pdata = of_get_coresight_platform_data(dev, pdev->dev.of_node);
+		if (IS_ERR(pdata))
+			return PTR_ERR(pdata);
+		pdev->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 = &pdev->dev;
+	platform_set_drvdata(pdev, drvdata);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	drvdata->base = devm_ioremap(dev, res->start, resource_size(res));
+	if (!drvdata->base)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (!res)
+		return -ENODEV;
+
+	if (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 {
+		res_size = min((resource_size_t)(NR_STM_CHANNEL *
+				 BYTES_PER_CHANNEL), resource_size(res));
+		bitmap_size = NR_STM_CHANNEL * sizeof(long);
+	}
+	drvdata->chs.base = devm_ioremap(dev, res->start, res_size);
+	if (!drvdata->chs.base)
+		return -ENOMEM;
+	drvdata->chs.bitmap = devm_kzalloc(dev, bitmap_size, GFP_KERNEL);
+	if (!drvdata->chs.bitmap)
+		return -ENOMEM;
+
+	spin_lock_init(&drvdata->spinlock);
+
+	drvdata->clk = devm_clk_get(dev, "core_clk");
+	if (IS_ERR(drvdata->clk))
+		return PTR_ERR(drvdata->clk);
+
+	ret = clk_set_rate(drvdata->clk, CORESIGHT_CLK_RATE_TRACE);
+	if (ret)
+		return ret;
+
+	bitmap_fill(drvdata->entities, OST_ENTITY_MAX);
+
+	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 = pdev->dev.platform_data;
+	desc->dev = &pdev->dev;
+	desc->groups = stm_attr_grps;
+	desc->owner = THIS_MODULE;
+	drvdata->csdev = coresight_register(desc);
+	if (IS_ERR(drvdata->csdev))
+		return PTR_ERR(drvdata->csdev);
+
+	drvdata->miscdev.name = ((struct coresight_platform_data *)
+				 (pdev->dev.platform_data))->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");
+
+	if (boot_enable)
+		coresight_enable(drvdata->csdev);
+
+	return 0;
+err:
+	coresight_unregister(drvdata->csdev);
+	return ret;
+}
+
+static int __devexit stm_remove(struct platform_device *pdev)
+{
+	struct stm_drvdata *drvdata = platform_get_drvdata(pdev);
+
+	misc_deregister(&drvdata->miscdev);
+	coresight_unregister(drvdata->csdev);
+	return 0;
+}
+
+static struct of_device_id stm_match[] = {
+	{.compatible = "arm,coresight-stm"},
+	{}
+};
+
+static struct platform_driver stm_driver = {
+	.probe          = stm_probe,
+	.remove         = __devexit_p(stm_remove),
+	.driver         = {
+		.name   = "coresight-stm",
+		.owner	= THIS_MODULE,
+		.of_match_table = stm_match,
+	},
+};
+
+static int __init stm_init(void)
+{
+	return platform_driver_register(&stm_driver);
+}
+module_init(stm_init);
+
+static void __exit stm_exit(void)
+{
+	platform_driver_unregister(&stm_driver);
+}
+module_exit(stm_exit);
+
+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 0000000..15d6f8c
--- /dev/null
+++ b/include/linux/coresight-stm.h
@@ -0,0 +1,51 @@
+#ifndef _LINUX_CORESIGHT_STM_H
+#define _LINUX_CORESIGHT_STM_H
+
+enum {
+	OST_ENTITY_NONE			= 0x00,
+	OST_ENTITY_FTRACE_EVENTS	= 0x01,
+	OST_ENTITY_TRACE_PRINTK		= 0x02,
+	OST_ENTITY_TRACE_MARKER		= 0x04,
+	OST_ENTITY_DEV_NODE		= 0x08,
+	OST_ENTITY_QVIEW		= 0xFE,
+	OST_ENTITY_MAX			= 0xFF,
+};
+
+enum {
+	STM_OPTION_NONE			= 0x0,
+	STM_OPTION_TIMESTAMPED		= 0x08,
+	STM_OPTION_GUARANTEED		= 0x80,
+};
+
+#ifdef __KERNEL__
+#define stm_log_inv(entity_id, proto_id, data, size)			\
+	stm_trace(STM_OPTION_NONE, entity_id, proto_id, data, size)
+
+#define stm_log_inv_ts(entity_id, proto_id, data, size)			\
+	stm_trace(STM_OPTION_TIMESTAMPED, entity_id, proto_id,		\
+		  data, size)
+
+#define stm_log_gtd(entity_id, proto_id, data, size)			\
+	stm_trace(STM_OPTION_GUARANTEED, entity_id, proto_id,		\
+		  data, size)
+
+#define stm_log_gtd_ts(entity_id, proto_id, data, size)			\
+	stm_trace(STM_OPTION_GUARANTEED | STM_OPTION_TIMESTAMPED,	\
+		  entity_id, proto_id, data, size)
+
+#define stm_log(entity_id, data, size)					\
+	stm_log_inv_ts(entity_id, 0, data, size)
+
+#ifdef CONFIG_CORESIGHT_SOURCE_STM
+extern int stm_trace(uint32_t options, uint8_t entity_id, uint8_t proto_id,
+		     const void *data, uint32_t size);
+#else
+static inline int stm_trace(uint32_t options, uint8_t entity_id,
+			    uint8_t proto_id, const void *data, uint32_t size)
+{
+	return 0;
+}
+#endif
+#endif /* __KERNEL__ */
+
+#endif
-- 
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