[PATCH v2] drivers/coresight: ultrasoc: Add System Memory Buffer driver

[Qi Liu]

This patch adds driver for Ultrasoc SMB(System Memory Buffer)
device. SMB provides a way to buffer messages from ETM, and
store these CPU instructions in system memory.

SMB is developed by Ultrasoc technology, which is acquired by
Siemens, and we still use "Ultrasoc" to name driver.

Signed-off-by: Qi Liu <liuqi115@xxxxxxxxxx>
Tested-by: JunHao He <hejunhao2@xxxxxxxxxxxxx>

---

Change since RFC:
- Move ultrasoc driver to drivers/hwtracing/coresight.
- Remove ultrasoc-axi-com.c, as AXI-COM doesn't need to be configured in
  basic tracing function.
- Remove ultrasoc.c as SMB does not need to register with the ultrasoc core.
- Address the comments from Mathieu and Suzuki.
- Link: https://lists.linaro.org/pipermail/coresight/2021-June/006535.html

Change since v1:
- Drop the document of Ultrasoc according to Mathieu's comment.
- Add comments to explain some private hardware settings.
- Address the comments from Mathieu.
- Link: https://lists.linaro.org/pipermail/coresight/2021-August/006842.html

 drivers/hwtracing/coresight/Kconfig           |   3 +
 drivers/hwtracing/coresight/Makefile          |   2 +
 drivers/hwtracing/coresight/ultrasoc/Kconfig  |  12 +
 drivers/hwtracing/coresight/ultrasoc/Makefile |   6 +
 .../coresight/ultrasoc/ultrasoc-smb.c         | 610 ++++++++++++++++++
 .../coresight/ultrasoc/ultrasoc-smb.h         | 116 ++++
 6 files changed, 749 insertions(+)
 create mode 100644 drivers/hwtracing/coresight/ultrasoc/Kconfig
 create mode 100644 drivers/hwtracing/coresight/ultrasoc/Makefile
 create mode 100644 drivers/hwtracing/coresight/ultrasoc/ultrasoc-smb.c
 create mode 100644 drivers/hwtracing/coresight/ultrasoc/ultrasoc-smb.h

diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
index 514a9b8086e3..603430664729 100644
--- a/drivers/hwtracing/coresight/Kconfig
+++ b/drivers/hwtracing/coresight/Kconfig
@@ -201,4 +201,7 @@ config CORESIGHT_TRBE
 
 	  To compile this driver as a module, choose M here: the module will be
 	  called coresight-trbe.
+
+source "drivers/hwtracing/coresight/ultrasoc/Kconfig"
+
 endif
diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
index b6c4a48140ec..50491d57c500 100644
--- a/drivers/hwtracing/coresight/Makefile
+++ b/drivers/hwtracing/coresight/Makefile
@@ -27,3 +27,5 @@ obj-$(CONFIG_CORESIGHT_CTI) += coresight-cti.o
 obj-$(CONFIG_CORESIGHT_TRBE) += coresight-trbe.o
 coresight-cti-y := coresight-cti-core.o	coresight-cti-platform.o \
 		   coresight-cti-sysfs.o
+
+obj-$(CONFIG_ULTRASOC_SMB) += ultrasoc/
diff --git a/drivers/hwtracing/coresight/ultrasoc/Kconfig b/drivers/hwtracing/coresight/ultrasoc/Kconfig
new file mode 100644
index 000000000000..c18c25bf9df3
--- /dev/null
+++ b/drivers/hwtracing/coresight/ultrasoc/Kconfig
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: MIT
+#
+# ultrasoc configuration
+#
+config ULTRASOC_SMB
+	tristate "Ultrasoc system memory buffer drivers"
+        depends on ARM64 && CORESIGHT
+	help
+	  This enables support for the Ultrasoc system memory buffer
+	  driver that is responsible for receiving the trace data from
+	  Coresight ETM devices and storing them to a system buffer
+	  respectively.
diff --git a/drivers/hwtracing/coresight/ultrasoc/Makefile b/drivers/hwtracing/coresight/ultrasoc/Makefile
new file mode 100644
index 000000000000..8469be50fc6a
--- /dev/null
+++ b/drivers/hwtracing/coresight/ultrasoc/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for ultrasoc drivers.
+#
+
+obj-$(CONFIG_ULTRASOC_SMB) += ultrasoc-smb.o
diff --git a/drivers/hwtracing/coresight/ultrasoc/ultrasoc-smb.c b/drivers/hwtracing/coresight/ultrasoc/ultrasoc-smb.c
new file mode 100644
index 000000000000..f8a4ae705293
--- /dev/null
+++ b/drivers/hwtracing/coresight/ultrasoc/ultrasoc-smb.c
@@ -0,0 +1,610 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright (C) 2021 HiSilicon Limited.
+ *
+ * Code herein communicates with and accesses proprietary hardware which is
+ * licensed intellectual property (IP) belonging to Siemens Digital Industries
+ * Software Ltd.
+ *
+ * Siemens Digital Industries Software Ltd. asserts and reserves all rights to
+ * their intellectual property. This paragraph may not be removed or modified
+ * in any way without permission from Siemens Digital Industries Software Ltd.
+ */
+
+#include <linux/acpi.h>
+#include <linux/circ_buf.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+
+#include "ultrasoc-smb.h"
+
+DEFINE_CORESIGHT_DEVLIST(sink_devs, "sink_smb");
+
+static bool smb_buffer_is_empty(struct smb_drv_data *drvdata)
+{
+	u32 buf_status = readl(drvdata->base + SMB_LB_INT_STS);
+
+	return buf_status & BIT(0) ? false : true;
+}
+
+static bool smb_buffer_cmp_pointer(struct smb_drv_data *drvdata)
+{
+	u32 wr_offset, rd_offset;
+
+	wr_offset = readl(drvdata->base + SMB_LB_WR_ADDR);
+	rd_offset = readl(drvdata->base + SMB_LB_RD_ADDR);
+	return wr_offset == rd_offset;
+}
+
+static void smb_reset_buffer_status(struct smb_drv_data *drvdata)
+{
+	writel(0xf, drvdata->base + SMB_LB_INT_STS);
+}
+
+/* Purge data remaining in hardware path to SMB. */
+static void smb_purge_data(struct smb_drv_data *drvdata)
+{
+	writel(0x1, drvdata->base + SMB_LB_PURGE);
+}
+
+static void smb_update_data_size(struct smb_drv_data *drvdata)
+{
+	struct smb_data_buffer *sdb = &drvdata->sdb;
+	u32 write_offset;
+
+	smb_purge_data(drvdata);
+	if (smb_buffer_cmp_pointer(drvdata)) {
+		if (smb_buffer_is_empty(drvdata))
+			sdb->data_size = 0;
+		else
+			sdb->data_size = sdb->buf_size;
+		return;
+	}
+
+	write_offset = readl(drvdata->base + SMB_LB_WR_ADDR) - sdb->start_addr;
+	sdb->data_size = CIRC_CNT(write_offset, sdb->rd_offset, sdb->buf_size);
+}
+
+static int smb_open(struct inode *inode, struct file *file)
+{
+	struct smb_drv_data *drvdata = container_of(file->private_data,
+			struct smb_drv_data, miscdev);
+
+	if (local_cmpxchg(&drvdata->reading, 0, 1))
+		return -EBUSY;
+
+	return 0;
+}
+
+static ssize_t smb_read(struct file *file, char __user *data, size_t len, loff_t *ppos)
+{
+	struct smb_drv_data *drvdata = container_of(file->private_data,
+			struct smb_drv_data, miscdev);
+	struct smb_data_buffer *sdb = &drvdata->sdb;
+	struct device *dev = &drvdata->csdev->dev;
+	unsigned long flags;
+	int to_copy = 0;
+
+	spin_lock_irqsave(&drvdata->spinlock, flags);
+
+	if (!sdb->data_size) {
+		smb_update_data_size(drvdata);
+		if (!sdb->data_size)
+			goto out;
+	}
+
+	if (atomic_read(drvdata->csdev->refcnt)) {
+		to_copy = -EBUSY;
+		goto out;
+	}
+
+	to_copy = min(sdb->data_size, len);
+
+	/* Copy parts of trace data when the read pointer will wrap around SMB buffer. */
+	if (sdb->rd_offset + to_copy > sdb->buf_size)
+		to_copy = sdb->buf_size - sdb->rd_offset;
+
+	if (copy_to_user(data, (void *)sdb->buf_base + sdb->rd_offset, to_copy)) {
+		dev_dbg(dev, "Failed to copy data to user.\n");
+		to_copy = -EFAULT;
+		goto out;
+	}
+
+	*ppos += to_copy;
+	sdb->data_size -= to_copy;
+	sdb->rd_offset += to_copy;
+	sdb->rd_offset %= sdb->buf_size;
+	writel(sdb->start_addr + sdb->rd_offset, drvdata->base + SMB_LB_RD_ADDR);
+	dev_dbg(dev, "%d bytes copied.\n", to_copy);
+out:
+	if (!sdb->data_size)
+		smb_reset_buffer_status(drvdata);
+	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+	return to_copy;
+}
+
+static int smb_release(struct inode *inode, struct file *file)
+{
+	struct smb_drv_data *drvdata = container_of(file->private_data,
+			struct smb_drv_data, miscdev);
+	local_set(&drvdata->reading, 0);
+	return 0;
+}
+
+static const struct file_operations smb_fops = {
+	.owner		= THIS_MODULE,
+	.open		= smb_open,
+	.read		= smb_read,
+	.release	= smb_release,
+	.llseek		= no_llseek,
+};
+
+smb_simple_func(struct smb_drv_data, read_pos, SMB_LB_RD_ADDR);
+smb_simple_func(struct smb_drv_data, write_pos, SMB_LB_WR_ADDR);
+smb_simple_func(struct smb_drv_data, buf_status, SMB_LB_INT_STS);
+
+static ssize_t buf_size_show(struct device *dev,
+			   struct device_attribute *attr, char *buf)
+{
+	struct smb_drv_data *drvdata = dev_get_drvdata(dev->parent);
+
+	return sysfs_emit(buf, "0x%lx\n", drvdata->sdb.buf_size);
+}
+static DEVICE_ATTR_RO(buf_size);
+
+static struct attribute *smb_sink_attrs[] = {
+	&dev_attr_read_pos.attr,
+	&dev_attr_write_pos.attr,
+	&dev_attr_buf_status.attr,
+	&dev_attr_buf_size.attr,
+	NULL,
+};
+
+static const struct attribute_group smb_sink_group = {
+	.attrs = smb_sink_attrs,
+	.name = "status",
+};
+
+static const struct attribute_group *smb_sink_groups[] = {
+	&smb_sink_group,
+	NULL,
+};
+
+static int smb_set_perf_buffer(struct perf_output_handle *handle)
+{
+	struct cs_buffers *buf = etm_perf_sink_config(handle);
+	u32 head;
+
+	if (!buf)
+		return -EINVAL;
+
+	/* Wrap head around to the amount of space we have */
+	head = handle->head & ((buf->nr_pages << PAGE_SHIFT) - 1);
+
+	/* Find the page to write to and offset within that page */
+	buf->cur = head / PAGE_SIZE;
+	buf->offset = head % PAGE_SIZE;
+
+	local_set(&buf->data_size, 0);
+
+	return 0;
+}
+
+static void smb_enable_hw(struct smb_drv_data *drvdata)
+{
+	writel(0x1, drvdata->base + SMB_GLOBAL_EN);
+}
+
+static void smb_disable_hw(struct smb_drv_data *drvdata)
+{
+	writel(0x0, drvdata->base + SMB_GLOBAL_EN);
+}
+
+static int smb_enable_sysfs(struct smb_drv_data *drvdata)
+{
+	if (drvdata->mode == CS_MODE_PERF)
+		return -EBUSY;
+
+	if (drvdata->mode == CS_MODE_SYSFS)
+		return 0;
+
+	smb_enable_hw(drvdata);
+	drvdata->mode = CS_MODE_SYSFS;
+	return 0;
+}
+
+static int smb_enable_perf(struct smb_drv_data *drvdata, void *data)
+{
+	struct device *dev = &drvdata->csdev->dev;
+	struct perf_output_handle *handle = data;
+	pid_t pid;
+
+	if (drvdata->mode == CS_MODE_SYSFS) {
+		dev_err(dev, "Device is already in used by sysfs.\n");
+		return -EBUSY;
+	}
+
+	/* Get a handle on the pid of the target process*/
+	pid = task_pid_nr(handle->event->owner);
+	if (drvdata->pid != -1 && drvdata->pid != pid) {
+		dev_err(dev, "Device is already in used by other session.\n");
+		return -EBUSY;
+	}
+	/* The sink is already enabled by this session. */
+	if (drvdata->pid == pid)
+		return 0;
+
+	if (smb_set_perf_buffer(handle))
+		return -EINVAL;
+
+	smb_enable_hw(drvdata);
+	drvdata->pid = pid;
+	drvdata->mode = CS_MODE_PERF;
+
+	return 0;
+}
+
+static int smb_enable(struct coresight_device *csdev, u32 mode, void *data)
+{
+	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
+	unsigned long flags;
+	int ret = -EINVAL;
+
+	/* Do nothing if trace data is reading by other interface now. */
+	if (local_read(&drvdata->reading))
+		return -EBUSY;
+
+	spin_lock_irqsave(&drvdata->spinlock, flags);
+
+	if (mode == CS_MODE_SYSFS)
+		ret = smb_enable_sysfs(drvdata);
+
+	if (mode == CS_MODE_PERF)
+		ret = smb_enable_perf(drvdata, data);
+
+	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+
+	if (ret)
+		return ret;
+
+	atomic_inc(csdev->refcnt);
+	dev_dbg(&csdev->dev, "Ultrasoc SMB enabled.\n");
+
+	return 0;
+}
+
+static int smb_disable(struct coresight_device *csdev)
+{
+	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
+	unsigned long flags;
+
+	spin_lock_irqsave(&drvdata->spinlock, flags);
+
+	if (atomic_dec_return(csdev->refcnt)) {
+		spin_unlock_irqrestore(&drvdata->spinlock, flags);
+		return -EBUSY;
+	}
+
+	WARN_ON_ONCE(drvdata->mode == CS_MODE_DISABLED);
+	smb_disable_hw(drvdata);
+
+	/*
+	 * Data remaining in hardware path will be sent to SMB after purge, so needs to
+	 * synchronize the read pointer to write pointer in perf mode.
+	 */
+	smb_purge_data(drvdata);
+	if (drvdata->mode == CS_MODE_PERF)
+		writel(readl(drvdata->base + SMB_LB_WR_ADDR),
+			drvdata->base + SMB_LB_RD_ADDR);
+
+	/* Dissociate from the target process. */
+	drvdata->pid = -1;
+	drvdata->mode = CS_MODE_DISABLED;
+	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+
+	dev_dbg(&csdev->dev, "Ultrasoc SMB disabled.\n");
+	return 0;
+}
+
+static void *smb_alloc_buffer(struct coresight_device *csdev,
+			      struct perf_event *event, void **pages,
+			      int nr_pages, bool overwrite)
+{
+	struct cs_buffers *buf;
+	int node;
+
+	node = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu);
+	buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node);
+	if (!buf)
+		return NULL;
+
+	buf->snapshot = overwrite;
+	buf->nr_pages = nr_pages;
+	buf->data_pages = pages;
+
+	return buf;
+}
+
+static void smb_free_buffer(void *config)
+{
+	struct cs_buffers *buf = config;
+
+	kfree(buf);
+}
+
+static void smb_sync_perf_buffer(struct smb_drv_data *drvdata,
+				 struct cs_buffers *buf, unsigned long data_size)
+{
+	struct smb_data_buffer *sdb = &drvdata->sdb;
+	char **dst_pages = (char **)buf->data_pages;
+	unsigned long buf_offset = buf->offset;
+	unsigned int cur = buf->cur;
+	unsigned long to_copy;
+
+	while (data_size) {
+		/* Copy parts of trace data when the read pointer will wrap around SMB buffer. */
+		if (sdb->rd_offset + PAGE_SIZE - buf_offset > sdb->buf_size)
+			to_copy = sdb->buf_size - sdb->rd_offset;
+		else
+			to_copy = min(data_size, PAGE_SIZE - buf_offset);
+
+		memcpy_fromio(dst_pages[cur] + buf_offset, sdb->buf_base + sdb->rd_offset, to_copy);
+
+		buf_offset += to_copy;
+		if (buf_offset >= PAGE_SIZE) {
+			buf_offset = 0;
+			cur++;
+			cur %= buf->nr_pages;
+		}
+		data_size -= to_copy;
+		/* ensure memcpy finished before update the read pointer */
+		sdb->rd_offset += to_copy;
+		sdb->rd_offset %= sdb->buf_size;
+	}
+
+	sdb->data_size = 0;
+	writel(sdb->start_addr + sdb->rd_offset, drvdata->base + SMB_LB_RD_ADDR);
+	smb_reset_buffer_status(drvdata);
+}
+
+static unsigned long smb_update_buffer(struct coresight_device *csdev,
+				       struct perf_output_handle *handle,
+				       void *sink_config)
+{
+	struct smb_drv_data *drvdata = dev_get_drvdata(csdev->dev.parent);
+	struct smb_data_buffer *sdb = &drvdata->sdb;
+	struct cs_buffers *buf = sink_config;
+	unsigned long data_size = 0;
+	unsigned long flags;
+	bool lost = false;
+
+	if (!buf)
+		return 0;
+
+	spin_lock_irqsave(&drvdata->spinlock, flags);
+
+	/* Don't do anything if another tracer is using this sink. */
+	if (atomic_read(csdev->refcnt) != 1)
+		goto out;
+
+	smb_update_data_size(drvdata);
+	data_size = sdb->data_size;
+	if (data_size > handle->size) {
+		sdb->rd_offset += data_size - handle->size;
+		sdb->rd_offset %= sdb->buf_size;
+		data_size = handle->size;
+		lost = true;
+	}
+
+	smb_sync_perf_buffer(drvdata, buf, data_size);
+	if (!buf->snapshot && lost)
+		perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);
+
+out:
+	spin_unlock_irqrestore(&drvdata->spinlock, flags);
+	return data_size;
+}
+
+static const struct coresight_ops_sink smb_cs_ops = {
+	.enable		= smb_enable,
+	.disable	= smb_disable,
+	.alloc_buffer	= smb_alloc_buffer,
+	.free_buffer	= smb_free_buffer,
+	.update_buffer	= smb_update_buffer,
+};
+
+static const struct coresight_ops cs_ops = {
+	.sink_ops	= &smb_cs_ops,
+};
+
+static int smb_init_data_buffer(struct platform_device *pdev, struct smb_data_buffer *sdb)
+{
+	struct resource *res;
+	void __iomem *base;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (IS_ERR(res)) {
+		dev_err(&pdev->dev, "SMB device without data buffer.\n");
+		return -EINVAL;
+	}
+
+	sdb->start_addr = res->start & SMB_BASE_LOW_MASK;
+	sdb->buf_size = resource_size(res);
+	if (sdb->buf_size == 0)
+		return -EINVAL;
+
+	base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	sdb->buf_base = base;
+
+	return 0;
+}
+
+static void smb_init_hw(struct smb_drv_data *drvdata)
+{
+	u32 value;
+
+	/* First disable smb and clear the status of SMB buffer */
+	smb_reset_buffer_status(drvdata);
+	smb_disable_hw(drvdata);
+	smb_purge_data(drvdata);
+
+	/* Using smb in single-end mode, and set other configures default */
+	value = SMB_BUF_CFG_STREAMING | SMB_BUF_SINGLE_END | SMB_BUF_EN;
+	writel(value, drvdata->base + SMB_LB_CFG_LO);
+	value = SMB_MSG_FILTER(0x0, 0xff);
+	writel(value, drvdata->base + SMB_LB_CFG_HI);
+
+	writel(SMB_GLOBAL_CFG, drvdata->base + SMB_CFG_REG);
+	writel(SMB_GLB_INT_CFG, drvdata->base + SMB_GLOBAL_INT);
+	writel(SMB_BUF_INT_CFG, drvdata->base + SMB_LB_INT_CTRL);
+}
+
+static int smb_register_sink(struct platform_device *pdev,
+			     struct smb_drv_data *drvdata)
+{
+	struct coresight_platform_data *pdata = NULL;
+	struct coresight_desc desc = { 0 };
+	int ret;
+
+	pdata = coresight_get_platform_data(&pdev->dev);
+	if (IS_ERR(pdata))
+		return PTR_ERR(pdata);
+
+	desc.type = CORESIGHT_DEV_TYPE_SINK;
+	desc.subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_BUFFER;
+	desc.ops = &cs_ops;
+	desc.pdata = pdata;
+	desc.dev = &pdev->dev;
+	desc.groups = smb_sink_groups;
+	desc.name = coresight_alloc_device_name(&sink_devs, &pdev->dev);
+	if (!desc.name) {
+		dev_err(&pdev->dev, "Failed to alloc coresight device name.");
+		return -ENOMEM;
+	}
+
+	drvdata->csdev = coresight_register(&desc);
+	if (IS_ERR(drvdata->csdev))
+		return PTR_ERR(drvdata->csdev);
+
+	drvdata->miscdev.name = desc.name;
+	drvdata->miscdev.minor = MISC_DYNAMIC_MINOR;
+	drvdata->miscdev.fops = &smb_fops;
+	ret = misc_register(&drvdata->miscdev);
+	if (ret) {
+		coresight_unregister(drvdata->csdev);
+		dev_err(&pdev->dev, "Failed to register misc, ret=%d.\n", ret);
+	}
+
+	return ret;
+}
+
+static void smb_unregister_sink(struct smb_drv_data *drvdata)
+{
+	misc_deregister(&drvdata->miscdev);
+	coresight_unregister(drvdata->csdev);
+}
+
+/*
+ * Send ultrasoc messge to control hardwares on the tracing path,
+ * using DSM calls to avoid exposing ultrasoc message format.
+ */
+static int smb_config_inport(struct device *dev, bool enable)
+{
+	u32 flag = enable ? 1 : 0;
+	union acpi_object *obj;
+	guid_t guid;
+
+	if (guid_parse("82ae1283-7f6a-4cbe-aa06-53e8fb24db18", &guid)) {
+		dev_err(dev, "Get GUID failed.\n");
+		return -EINVAL;
+	}
+
+	obj = acpi_evaluate_dsm(ACPI_HANDLE(dev), &guid, 0, flag, NULL);
+	if (!obj)
+		dev_err(dev, "ACPI handle failed!\n");
+
+	ACPI_FREE(obj);
+
+	return 0;
+}
+
+static int smb_probe(struct platform_device *pdev)
+{
+	struct smb_drv_data *drvdata;
+	int ret;
+
+	drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
+
+	drvdata->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(drvdata->base)) {
+		dev_err(&pdev->dev, "Failed to ioremap resource.\n");
+		return PTR_ERR(drvdata->base);
+	}
+
+	ret = smb_init_data_buffer(pdev, &drvdata->sdb);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to init buffer, ret = %d.\n", ret);
+		return ret;
+	}
+
+	smb_init_hw(drvdata);
+	spin_lock_init(&drvdata->spinlock);
+	drvdata->pid = -1;
+
+	ret = smb_register_sink(pdev, drvdata);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to register smb sink.\n");
+		return ret;
+	}
+
+	ret = smb_config_inport(&pdev->dev, true);
+	if (ret) {
+		smb_unregister_sink(drvdata);
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, drvdata);
+	return 0;
+}
+
+static int smb_remove(struct platform_device *pdev)
+{
+	struct smb_drv_data *drvdata = platform_get_drvdata(pdev);
+	int ret;
+
+	ret = smb_config_inport(&pdev->dev, false);
+	if (ret)
+		return ret;
+
+	smb_unregister_sink(drvdata);
+	return 0;
+}
+
+static const struct acpi_device_id ultrasoc_smb_acpi_match[] = {
+	{"HISI03A1", 0},
+	{},
+};
+MODULE_DEVICE_TABLE(acpi, ultrasoc_smb_acpi_match);
+
+static struct platform_driver smb_driver = {
+	.driver = {
+		.name = "ultrasoc,smb",
+		.acpi_match_table = ACPI_PTR(ultrasoc_smb_acpi_match),
+		.suppress_bind_attrs = true,
+	},
+	.probe = smb_probe,
+	.remove = smb_remove,
+};
+module_platform_driver(smb_driver);
+
+MODULE_DESCRIPTION("Ultrasoc smb driver");
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_AUTHOR("Jonathan Zhou <jonathan.zhouwen@xxxxxxxxxx>");
+MODULE_AUTHOR("Qi Liu <liuqi115@xxxxxxxxxx>");
diff --git a/drivers/hwtracing/coresight/ultrasoc/ultrasoc-smb.h b/drivers/hwtracing/coresight/ultrasoc/ultrasoc-smb.h
new file mode 100644
index 000000000000..01cb846aeedc
--- /dev/null
+++ b/drivers/hwtracing/coresight/ultrasoc/ultrasoc-smb.h
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright (C) 2021 HiSilicon Limited.
+ *
+ * Code herein communicates with and accesses proprietary hardware which is
+ * licensed intellectual property (IP) belonging to Siemens Digital Industries
+ * Software Ltd.
+ *
+ * Siemens Digital Industries Software Ltd. asserts and reserves all rights to
+ * their intellectual property. This paragraph may not be removed or modified
+ * in any way without permission from Siemens Digital Industries Software Ltd.
+ */
+
+#ifndef _ULTRASOC_SMB_H
+#define _ULTRASOC_SMB_H
+
+#include <linux/coresight.h>
+#include <linux/list.h>
+#include <linux/miscdevice.h>
+
+#include "../coresight-etm-perf.h"
+#include "../coresight-priv.h"
+
+/* Offset of SMB logical buffer registers */
+#define SMB_CFG_REG			0X0
+#define SMB_GLOBAL_EN			0X4
+#define SMB_GLOBAL_INT			0X8
+#define SMB_LB_CFG_LO			0X40
+#define SMB_LB_CFG_HI			0X44
+#define SMB_LB_INT_CTRL			0X48
+#define SMB_LB_INT_STS			0X4C
+#define SMB_LB_LIMIT			0X58
+#define SMB_LB_RD_ADDR			0X5C
+#define SMB_LB_WR_ADDR			0X60
+#define SMB_LB_PURGE			0X64
+
+/* Set SMB_CFG_REG register */
+#define SMB_IDLE_PRD(period)		(((period - 216) & 0xf) << 12)
+#define SMB_MEM_WR(credit, rate)	(((credit) << 16) | ((rate) << 18))
+#define SMB_MEM_RD(credit, rate)	(((credit) << 22) | ((rate) << 24))
+#define SMB_BURST_LEN(len)		((len - 1) << 4)
+#define SMB_GLOBAL_CFG			(SMB_IDLE_PRD(231) | SMB_MEM_WR(0x3, 0x0) |   \
+					 SMB_MEM_RD(0x3, 0x6) | SMB_BURST_LEN(16))
+
+/* Set SMB_GLOBAL_INT register */
+#define SMB_INT_EN			BIT(0)
+#define SMB_INT_TYPE_PULSE		BIT(1)
+#define SMB_INT_POLARITY_HIGH		BIT(2)
+#define SMB_GLB_INT_CFG			(SMB_INT_EN | SMB_INT_TYPE_PULSE | SMB_INT_POLARITY_HIGH)
+
+/* Set SMB_LB_CFG_LO register */
+#define SMB_BUF_EN			BIT(0)
+#define SMB_BUF_SINGLE_END		BIT(1)
+#define SMB_BUF_INIT			BIT(8)
+#define SMB_BUF_CONTINUOUS		BIT(11)
+#define SMB_FLOW_MASK			GENMASK(19, 16)
+#define SMB_BUF_CFG_STREAMING		(SMB_BUF_INIT | SMB_BUF_CONTINUOUS | SMB_FLOW_MASK)
+#define SMB_BASE_LOW_MASK		GENMASK(31, 0)
+
+/* Set SMB_LB_CFG_HI register */
+#define SMB_MSG_FILTER(lower, upper)	((lower & 0xff) | ((upper & 0xff) << 8))
+#define SMB_BUF_INT_EN			BIT(0)
+#define SMB_BUF_NOTE_MASK		GENMASK(11, 8)
+#define SMB_BUF_INT_CFG			(SMB_BUF_INT_EN | SMB_BUF_NOTE_MASK)
+
+/**
+ * struct smb_data_buffer - Details of the buffer used by SMB
+ * @buf_base	: Memory mapped base address of SMB.
+ * @start_addr	: SMB buffer start Physical address.
+ * @buf_size	: Size of the buffer.
+ * @data_size	: Size of Trace data copy to userspace.
+ * @rd_offset	: Offset of the read pointer in the buffer.
+ */
+struct smb_data_buffer {
+	void __iomem *buf_base;
+	u32 start_addr;
+	unsigned long buf_size;
+	unsigned long data_size;
+	unsigned long rd_offset;
+};
+
+/**
+ * struct smb_drv_data - specifics associated to an SMB component
+ * @base:	Memory mapped base address for SMB component.
+ * @csdev:	Component vitals needed by the framework.
+ * @sdb:	Data buffer for SMB.
+ * @miscdev:	Specifics to handle "/dev/xyz.tmc" entry.
+ * @spinlock:	Only one at a time pls.
+ * @reading:	Synchronise user space access to SMB buffer.
+ * @pid:	Process ID of the process being monitored by the session
+ *		that is using this component.
+ * @mode:	how this SMB is being used, perf mode or sysfs mode.
+ */
+struct smb_drv_data {
+	void __iomem *base;
+	struct coresight_device	*csdev;
+	struct smb_data_buffer sdb;
+	struct miscdevice miscdev;
+	spinlock_t spinlock;
+	local_t reading;
+	pid_t pid;
+	u32 mode;
+};
+
+#define smb_simple_func(type, name, offset)				\
+static ssize_t name##_show(struct device *_dev,				\
+			   struct device_attribute *attr, char *buf)	\
+{									\
+	type *drvdata = dev_get_drvdata(_dev->parent);			\
+	u32 val = readl(drvdata->base + offset);				\
+									\
+	return sysfs_emit(buf, "0x%x\n", val);			\
+}									\
+static DEVICE_ATTR_RO(name)
+
+#endif
-- 
2.33.0