[PATCH v7 6/9] drivers: perf: hisi: Add support for Hisilicon Djtag driver

[Anurup M]

From: Tan Xiaojun <tanxiaojun@xxxxxxxxxx>

The Hisilicon Djtag is an independent component which connects
with some other components in the SoC by Debug Bus. This driver
can be configured to access the registers of connecting components
(like L3 cache) during real time debugging.

Signed-off-by: Tan Xiaojun <tanxiaojun@xxxxxxxxxx>
Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
Signed-off-by: Anurup M <anurup.m@xxxxxxxxxx>
---
 drivers/perf/Makefile           |   1 +
 drivers/perf/hisilicon/Makefile |   1 +
 drivers/perf/hisilicon/djtag.c  | 684 ++++++++++++++++++++++++++++++++++++++++
 drivers/perf/hisilicon/djtag.h  |  47 +++
 4 files changed, 733 insertions(+)
 create mode 100644 drivers/perf/hisilicon/Makefile
 create mode 100644 drivers/perf/hisilicon/djtag.c
 create mode 100644 drivers/perf/hisilicon/djtag.h

diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
index ef24833..a1fa1e2 100644
--- a/drivers/perf/Makefile
+++ b/drivers/perf/Makefile
@@ -1,3 +1,4 @@
 obj-$(CONFIG_ARM_PMU) += arm_pmu.o
+obj-$(CONFIG_HISI_PMU) += hisilicon/
 obj-$(CONFIG_QCOM_L2_PMU)	+= qcom_l2_pmu.o
 obj-$(CONFIG_XGENE_PMU) += xgene_pmu.o
diff --git a/drivers/perf/hisilicon/Makefile b/drivers/perf/hisilicon/Makefile
new file mode 100644
index 0000000..be8f093
--- /dev/null
+++ b/drivers/perf/hisilicon/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_HISI_PMU) += djtag.o
diff --git a/drivers/perf/hisilicon/djtag.c b/drivers/perf/hisilicon/djtag.c
new file mode 100644
index 0000000..c1b6475
--- /dev/null
+++ b/drivers/perf/hisilicon/djtag.c
@@ -0,0 +1,684 @@
+/*
+ * Driver for Hisilicon Djtag r/w which use CPU sysctrl.
+ *
+ * Copyright (C) 2017 Hisilicon Limited
+ * Author: Tan Xiaojun <tanxiaojun@xxxxxxxxxx>
+ *         Anurup M <anurup.m@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/bitops.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/idr.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/time64.h>
+
+#include "djtag.h"
+
+/*
+ * Timeout of 100ms is used to retry on djtag access busy condition.
+ * If djtag unavailable event after timeout, it means some serious
+ * hardware condition where we would BUG_ON, as subsequent access
+ * are also likely to FAIL.
+ */
+#define SC_DJTAG_TIMEOUT_US    (100 * USEC_PER_MSEC)
+
+#define DJTAG_PREFIX "hisi-djtag-dev-"
+
+/* for djtag v1 */
+#define SC_DJTAG_MSTR_EN		0x6800
+#define DJTAG_NOR_CFG			BIT(1)	/* normal RW mode */
+#define DJTAG_MSTR_EN			BIT(0)
+#define SC_DJTAG_MSTR_START_EN		0x6804
+#define DJTAG_MSTR_START_EN		0x1
+#define SC_DJTAG_DEBUG_MODULE_SEL	0x680c
+#define SC_DJTAG_MSTR_WR		0x6810
+#define DJTAG_MSTR_W			0x1
+#define DJTAG_MSTR_R			0x0
+#define SC_DJTAG_CHAIN_UNIT_CFG_EN	0x6814
+#define CHAIN_UNIT_CFG_EN		0xFFFF
+#define SC_DJTAG_MSTR_ADDR		0x6818
+#define SC_DJTAG_MSTR_DATA		0x681c
+#define SC_DJTAG_RD_DATA_BASE		0xe800
+
+/* for djtag v2 */
+#define SC_DJTAG_SEC_ACC_EN_EX		0xd800
+#define DJTAG_SEC_ACC_EN_EX		0x1
+#define SC_DJTAG_MSTR_CFG_EX		0xd818
+#define DJTAG_MSTR_RW_SHIFT_EX		29
+#define DJTAG_MSTR_RD_EX		(0x0 << DJTAG_MSTR_RW_SHIFT_EX)
+#define DJTAG_MSTR_WR_EX		(0x1 << DJTAG_MSTR_RW_SHIFT_EX)
+#define DEBUG_MODULE_SEL_SHIFT_EX	16
+#define CHAIN_UNIT_CFG_EN_EX		0xFFFF
+#define SC_DJTAG_MSTR_ADDR_EX		0xd810
+#define SC_DJTAG_MSTR_DATA_EX		0xd814
+#define SC_DJTAG_MSTR_START_EN_EX	0xd81c
+#define DJTAG_MSTR_START_EN_EX		0x1
+#define SC_DJTAG_RD_DATA_BASE_EX	0xe800
+#define SC_DJTAG_OP_ST_EX		0xe828
+#define DJTAG_OP_DONE_EX		BIT(8)
+
+#define DJTAG_SYSCTRL_ADDR_SIZE		0x10000
+
+static DEFINE_IDR(djtag_hosts_idr);
+static DEFINE_IDR(djtag_clients_idr);
+
+struct hisi_djtag_ops {
+	void (*djtag_read)(void __iomem *regs_base, u32 offset,
+			   u32 mod_sel, u32 mod_mask, int chain_id, u32 *rval);
+	void (*djtag_write)(void __iomem *regs_base, u32 offset,
+			    u32 mod_sel, u32 mod_mask, u32 wval, int chain_id);
+};
+
+struct hisi_djtag_host {
+	spinlock_t lock;
+	int id;
+	u32 scl_id;
+	struct device dev;
+	struct list_head client_list;
+	void __iomem *sysctl_reg_map;
+	struct device_node *of_node;
+	const struct hisi_djtag_ops *djtag_ops;
+};
+
+#define to_hisi_djtag_client(d) container_of(d, struct hisi_djtag_client, dev)
+#define to_hisi_djtag_driver(d) container_of(d, struct hisi_djtag_driver, \
+					     driver)
+#define MODULE_PREFIX "hisi_djtag:"
+
+static void hisi_djtag_prepare_v1(void __iomem *regs_base, u32 offset,
+				  u32 mod_sel, u32 mod_mask)
+{
+	/* djtag master enable and support normal mode for R,W */
+	writel(DJTAG_NOR_CFG | DJTAG_MSTR_EN, regs_base + SC_DJTAG_MSTR_EN);
+
+	/* select module */
+	writel(mod_sel, regs_base + SC_DJTAG_DEBUG_MODULE_SEL);
+	writel(mod_mask & CHAIN_UNIT_CFG_EN,
+	       regs_base + SC_DJTAG_CHAIN_UNIT_CFG_EN);
+
+	/* address offset */
+	writel(offset, regs_base + SC_DJTAG_MSTR_ADDR);
+}
+
+static void hisi_djtag_do_operation_v1(void __iomem *regs_base)
+{
+	u32 val;
+	int ret;
+
+	/* start to write to djtag register */
+	writel(DJTAG_MSTR_START_EN, regs_base + SC_DJTAG_MSTR_START_EN);
+
+	/* ensure the djtag operation is done */
+	ret = readl_poll_timeout_atomic(regs_base + SC_DJTAG_MSTR_START_EN,
+					val, !(val & DJTAG_MSTR_EN), 1,
+					SC_DJTAG_TIMEOUT_US);
+	/*
+	 * Djtag access busy even after timeout indicate a serious hardware
+	 * condition. BUG_ON as subsequent access are also likely to go wrong.
+	 */
+	BUG_ON(ret == -ETIMEDOUT);
+}
+
+static void hisi_djtag_prepare_v2(void __iomem *regs_base, u32 offset,
+				  u32 mod_sel, u32 mod_mask)
+{
+	/* djtag mster enable */
+	writel(DJTAG_SEC_ACC_EN_EX, regs_base + SC_DJTAG_SEC_ACC_EN_EX);
+
+	/* address offset */
+	writel(offset, regs_base + SC_DJTAG_MSTR_ADDR_EX);
+}
+
+static void hisi_djtag_do_operation_v2(void __iomem *regs_base)
+{
+	u32 val;
+	int ret;
+
+	/* start to write to djtag register */
+	writel(DJTAG_MSTR_START_EN_EX, regs_base + SC_DJTAG_MSTR_START_EN_EX);
+
+	/* ensure the djtag operation is done */
+	ret = readl_poll_timeout_atomic(regs_base + SC_DJTAG_MSTR_START_EN_EX,
+					val, !(val & DJTAG_MSTR_START_EN_EX), 1,
+					SC_DJTAG_TIMEOUT_US);
+	/*
+	 * Djtag access busy even after timeout indicate a serious hardware
+	 * condition. BUG_ON as subsequent access are also likely to go wrong.
+	 */
+	BUG_ON(ret == -ETIMEDOUT);
+
+	/* wait for the operation to complete */
+	ret = readl_poll_timeout_atomic(regs_base + SC_DJTAG_OP_ST_EX,
+					val, (val & DJTAG_OP_DONE_EX), 1,
+					SC_DJTAG_TIMEOUT_US);
+
+	/*
+	 * Djtag access busy even after timeout indicate a serious hardware
+	 * condition. BUG_ON as subsequent access are also likely to go wrong.
+	 */
+	BUG_ON(ret == -ETIMEDOUT);
+}
+
+/*
+ * hisi_djtag_read_v1/v2: djtag read interface
+ * @reg_base:	djtag register base address
+ * @offset:	register's offset
+ * @mod_sel:	module selection
+ * @mod_mask:	mask to select specific modules for read
+ * @chain_id:	which sub module to read
+ * @rval:	value read from register
+ *
+ * Return - none.
+ */
+static void hisi_djtag_read_v1(void __iomem *regs_base, u32 offset, u32 mod_sel,
+			       u32 mod_mask, int chain_id, u32 *rval)
+{
+	hisi_djtag_prepare_v1(regs_base, offset, mod_sel, mod_mask);
+
+	writel(DJTAG_MSTR_R, regs_base + SC_DJTAG_MSTR_WR);
+
+	hisi_djtag_do_operation_v1(regs_base);
+
+	*rval = readl(regs_base + SC_DJTAG_RD_DATA_BASE + chain_id * 0x4);
+}
+
+static void hisi_djtag_read_v2(void __iomem *regs_base, u32 offset, u32 mod_sel,
+			       u32 mod_mask, int chain_id, u32 *rval)
+{
+	u32 val = DJTAG_MSTR_RD_EX |
+		(mod_sel << DEBUG_MODULE_SEL_SHIFT_EX) |
+		(mod_mask & CHAIN_UNIT_CFG_EN_EX);
+
+	hisi_djtag_prepare_v2(regs_base, offset, mod_sel, mod_mask);
+
+	writel(val, regs_base + SC_DJTAG_MSTR_CFG_EX);
+
+	hisi_djtag_do_operation_v2(regs_base);
+
+	*rval = readl(regs_base + SC_DJTAG_RD_DATA_BASE_EX + chain_id * 0x4);
+}
+
+/*
+ * hisi_djtag_write_v1/v2: djtag write interface
+ * @reg_base:	djtag register base address
+ * @offset:	register's offset
+ * @mod_sel:	module selection
+ * @mod_mask:	mask to select specific modules for write
+ * @wval:	value to write to register
+ * @chain_id:	which sub module to write
+ *
+ * Return - none.
+ */
+static void hisi_djtag_write_v1(void __iomem *regs_base, u32 offset,
+				u32 mod_sel, u32 mod_mask, u32 wval,
+				int chain_id)
+{
+	hisi_djtag_prepare_v1(regs_base, offset, mod_sel, mod_mask);
+
+	writel(DJTAG_MSTR_W, regs_base + SC_DJTAG_MSTR_WR);
+	writel(wval, regs_base + SC_DJTAG_MSTR_DATA);
+
+	hisi_djtag_do_operation_v1(regs_base);
+}
+
+static void hisi_djtag_write_v2(void __iomem *regs_base, u32 offset,
+				u32 mod_sel, u32 mod_mask, u32 wval,
+				int chain_id)
+{
+	u32 val = DJTAG_MSTR_WR_EX |
+		(mod_sel << DEBUG_MODULE_SEL_SHIFT_EX) |
+		(mod_mask & CHAIN_UNIT_CFG_EN_EX);
+
+	hisi_djtag_prepare_v2(regs_base, offset, mod_sel, mod_mask);
+
+	writel(val, regs_base + SC_DJTAG_MSTR_CFG_EX);
+	writel(wval, regs_base + SC_DJTAG_MSTR_DATA_EX);
+
+	hisi_djtag_do_operation_v2(regs_base);
+}
+
+/*
+ * hisi_djtag_writel - write registers via djtag
+ * @client: djtag client handle
+ * @offset:	register's offset
+ * @mod_sel:	module selection
+ * @mod_mask:	mask to select specific modules
+ * @val:	value to write to register
+ *
+ * Return - none.
+ */
+void hisi_djtag_writel(struct hisi_djtag_client *client, u32 offset,
+		       u32 mod_sel, u32 mod_mask, u32 val)
+{
+	struct hisi_djtag_host *host = client->host;
+	void __iomem *reg_map = host->sysctl_reg_map;
+	const struct hisi_djtag_ops *ops = host->djtag_ops;
+	unsigned long flags;
+
+	spin_lock_irqsave(&host->lock, flags);
+	ops->djtag_write(reg_map, offset, mod_sel, mod_mask, val, 0);
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
+/*
+ * hisi_djtag_readl - read registers via djtag
+ * @client: djtag client handle
+ * @offset:	register's offset
+ * @mod_sel:	module type selection
+ * @chain_id:	chain_id number, mostly is 0
+ * @val:	register's value
+ *
+ * Return - none.
+ */
+void hisi_djtag_readl(struct hisi_djtag_client *client, u32 offset,
+		      u32 mod_sel, int chain_id, u32 *val)
+{
+	struct hisi_djtag_host *host = client->host;
+	void __iomem *reg_map = host->sysctl_reg_map;
+	const struct hisi_djtag_ops *ops = host->djtag_ops;
+	unsigned long flags;
+
+	spin_lock_irqsave(&host->lock, flags);
+	ops->djtag_read(reg_map, offset, mod_sel, 0xffff, chain_id, val);
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
+u32 hisi_djtag_get_sclid(struct hisi_djtag_client *client)
+{
+	return client->host->scl_id;
+}
+
+static const struct hisi_djtag_ops djtag_v1_ops = {
+	.djtag_read  = hisi_djtag_read_v1,
+	.djtag_write  = hisi_djtag_write_v1,
+};
+
+static const struct hisi_djtag_ops djtag_v2_ops = {
+	.djtag_read  = hisi_djtag_read_v2,
+	.djtag_write  = hisi_djtag_write_v2,
+};
+
+static const struct of_device_id djtag_of_match[] = {
+	/* for hip05 CPU die */
+	{ .compatible = "hisilicon,hip05-cpu-djtag-v1",	.data = &djtag_v1_ops },
+	/* for hip05 IO die */
+	{ .compatible = "hisilicon,hip05-io-djtag-v1",	.data = &djtag_v1_ops },
+	/* for hip06 CPU die */
+	{ .compatible = "hisilicon,hip06-cpu-djtag-v1",	.data = &djtag_v1_ops },
+	/* for hip06 IO die */
+	{ .compatible = "hisilicon,hip06-io-djtag-v2",	.data = &djtag_v2_ops },
+	/* for hip07 CPU die */
+	{ .compatible = "hisilicon,hip07-cpu-djtag-v2",	.data = &djtag_v2_ops },
+	/* for hip07 IO die */
+	{ .compatible = "hisilicon,hip07-io-djtag-v2",	.data = &djtag_v2_ops },
+	{},
+};
+MODULE_DEVICE_TABLE(of, djtag_of_match);
+
+static ssize_t show_modalias(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct hisi_djtag_client *client = to_hisi_djtag_client(dev);
+
+	return sprintf(buf, "%s%s\n", MODULE_PREFIX, dev_name(&client->dev));
+}
+static DEVICE_ATTR(modalias, 0444, show_modalias, NULL);
+
+static struct attribute *hisi_djtag_dev_attrs[] = {
+	/* modalias helps coldplug:  modprobe $(cat .../modalias) */
+	&dev_attr_modalias.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(hisi_djtag_dev);
+
+static struct device_type hisi_djtag_client_type = {
+	.groups	= hisi_djtag_dev_groups,
+};
+
+static int hisi_djtag_device_probe(struct device *dev)
+{
+	struct hisi_djtag_driver *driver;
+	struct hisi_djtag_client *client;
+	int ret;
+
+	client = to_hisi_djtag_client(dev);
+	if (!client) {
+		dev_err(dev, "could not find client\n");
+		return -ENODEV;
+	}
+
+	driver = to_hisi_djtag_driver(dev->driver);
+	if (!driver) {
+		dev_err(dev, "could not find driver\n");
+		return -ENODEV;
+	}
+
+	ret = driver->probe(client);
+	if (ret < 0) {
+		dev_err(dev, "client probe failed\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int hisi_djtag_device_remove(struct device *dev)
+{
+	struct hisi_djtag_driver *driver;
+	struct hisi_djtag_client *client;
+	int ret;
+
+	client = to_hisi_djtag_client(dev);
+	if (!client) {
+		dev_err(dev, "could not find client\n");
+		return -ENODEV;
+	}
+
+	driver = to_hisi_djtag_driver(dev->driver);
+	if (!driver) {
+		dev_err(dev, "could not find driver\n");
+		return -ENODEV;
+	}
+
+	ret = driver->remove(client);
+	if (ret < 0) {
+		dev_err(dev, "client probe failed\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int hisi_djtag_device_match(struct device *dev,
+				   struct device_driver *drv)
+{
+	/* Attempt an OF style match */
+	if (of_driver_match_device(dev, drv))
+		return true;
+
+	return false;
+}
+
+struct bus_type hisi_djtag_bus = {
+	.name		= "hisi-djtag",
+	.match		= hisi_djtag_device_match,
+	.probe		= hisi_djtag_device_probe,
+	.remove		= hisi_djtag_device_remove,
+};
+
+static struct hisi_djtag_client *
+hisi_djtag_client_alloc(struct hisi_djtag_host *host)
+{
+	struct hisi_djtag_client *client;
+
+	client = kzalloc(sizeof(*client), GFP_KERNEL);
+	if (!client)
+		return NULL;
+
+	client->host = host;
+	client->dev.parent = &client->host->dev;
+	client->dev.bus = &hisi_djtag_bus;
+	client->dev.type = &hisi_djtag_client_type;
+
+	return client;
+}
+
+static int hisi_djtag_get_client_id(struct hisi_djtag_client *client)
+{
+	return idr_alloc(&djtag_clients_idr, client, 0, 0, GFP_KERNEL);
+}
+
+static int hisi_djtag_set_client_name(struct hisi_djtag_client *client,
+				      const char *device_name)
+{
+	char name[DJTAG_CLIENT_NAME_LEN];
+	int id;
+
+	id = hisi_djtag_get_client_id(client);
+	if (id < 0)
+		return id;
+
+	client->id = id;
+	snprintf(name, DJTAG_CLIENT_NAME_LEN, "%s%s_%d", DJTAG_PREFIX,
+		 device_name, client->id);
+	dev_set_name(&client->dev, "%s", name);
+
+	return 0;
+}
+
+static int hisi_djtag_new_of_device(struct hisi_djtag_host *host,
+				    struct device_node *node)
+{
+	struct hisi_djtag_client *client;
+	int ret;
+
+	client = hisi_djtag_client_alloc(host);
+	if (!client) {
+		dev_err(&host->dev, "DT: Client alloc fail!\n");
+		return -ENOMEM;
+	}
+
+	client->dev.of_node = of_node_get(node);
+
+	ret = hisi_djtag_set_client_name(client, node->name);
+	if (ret < 0) {
+		dev_err(&host->dev, "DT: Client set name fail!\n");
+		goto fail;
+	}
+
+	ret = device_register(&client->dev);
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"DT: error adding new device, ret=%d\n", ret);
+		idr_remove(&djtag_clients_idr, client->id);
+		goto fail;
+	}
+
+	list_add(&client->next, &host->client_list);
+
+	return 0;
+fail:
+	of_node_put(client->dev.of_node);
+	kfree(client);
+	return ret;
+}
+
+static void djtag_register_devices(struct hisi_djtag_host *host)
+{
+	struct device_node *node;
+
+	for_each_available_child_of_node(host->of_node, node) {
+		if (of_node_test_and_set_flag(node, OF_POPULATED))
+			continue;
+		if (hisi_djtag_new_of_device(host, node))
+			break;
+	}
+}
+
+static int hisi_djtag_add_host(struct hisi_djtag_host *host)
+{
+	int ret;
+
+	host->dev.bus = &hisi_djtag_bus;
+
+	ret = idr_alloc(&djtag_hosts_idr, host, 0, 0, GFP_KERNEL);
+	if (ret < 0) {
+		dev_err(&host->dev, "No available djtag host ID'!s\n");
+		return ret;
+	}
+	host->id = ret;
+
+	/* Suffix the unique ID and set djtag hostname */
+	dev_set_name(&host->dev, "djtag-host-%d", host->id);
+	ret = device_register(&host->dev);
+	if (ret < 0) {
+		dev_err(&host->dev,
+			"add_host dev register failed, ret=%d\n", ret);
+		idr_remove(&djtag_hosts_idr, host->id);
+		return ret;
+	}
+
+	djtag_register_devices(host);
+
+	return 0;
+}
+
+static int djtag_host_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct hisi_djtag_host *host;
+	const struct of_device_id *of_id;
+	struct resource *res;
+	int ret;
+
+	host = kzalloc(sizeof(*host), GFP_KERNEL);
+	if (!host)
+		return -ENOMEM;
+
+	of_id = of_match_device(djtag_of_match, dev);
+	if (!of_id) {
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	host->djtag_ops = of_id->data;
+	host->of_node = of_node_get(dev->of_node);
+
+	/* Find the SCL ID */
+	ret = device_property_read_u32(dev, "hisilicon,scl-id", &host->scl_id);
+	if (ret < 0)
+		goto fail;
+
+	spin_lock_init(&host->lock);
+	INIT_LIST_HEAD(&host->client_list);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(dev, "No reg resorces!\n");
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	if (resource_size(res) != DJTAG_SYSCTRL_ADDR_SIZE) {
+		dev_err(dev, "Incorrect djtag sysctrl address range!\n");
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	host->sysctl_reg_map = devm_ioremap_resource(dev, res);
+	if (IS_ERR(host->sysctl_reg_map)) {
+		dev_err(dev, "Unable to map sysctl registers!\n");
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	platform_set_drvdata(pdev, host);
+
+	ret = hisi_djtag_add_host(host);
+	if (ret) {
+		dev_err(dev, "add host failed, ret=%d\n", ret);
+		goto fail;
+	}
+
+	return 0;
+fail:
+	of_node_put(dev->of_node);
+	kfree(host);
+	return ret;
+}
+
+static int djtag_host_remove(struct platform_device *pdev)
+{
+	struct hisi_djtag_host *host;
+	struct hisi_djtag_client *client, *tmp;
+	struct list_head *client_list;
+
+	host = platform_get_drvdata(pdev);
+	client_list = &host->client_list;
+
+	list_for_each_entry_safe(client, tmp, client_list, next) {
+		list_del(&client->next);
+		device_unregister(&client->dev);
+		idr_remove(&djtag_clients_idr, client->id);
+		of_node_put(client->dev.of_node);
+		kfree(client);
+	}
+
+	device_unregister(&host->dev);
+	idr_remove(&djtag_hosts_idr, host->id);
+	of_node_put(host->of_node);
+	kfree(host);
+
+	return 0;
+}
+
+static struct platform_driver djtag_dev_driver = {
+	.driver = {
+		.name = "hisi-djtag",
+		.of_match_table = djtag_of_match,
+	},
+	.probe = djtag_host_probe,
+	.remove = djtag_host_remove,
+};
+module_platform_driver(djtag_dev_driver);
+
+int hisi_djtag_register_driver(struct module *owner,
+			       struct hisi_djtag_driver *driver)
+{
+	int ret;
+
+	driver->driver.owner = owner;
+	driver->driver.bus = &hisi_djtag_bus;
+
+	ret = driver_register(&driver->driver);
+	if (ret < 0)
+		pr_err("%s register failed, ret=%d\n", __func__, ret);
+
+	return ret;
+}
+
+void hisi_djtag_unregister_driver(struct hisi_djtag_driver *driver)
+{
+	driver->driver.bus = &hisi_djtag_bus;
+	driver_unregister(&driver->driver);
+}
+
+static int __init hisi_djtag_init(void)
+{
+	int ret;
+
+	ret = bus_register(&hisi_djtag_bus);
+	if (ret) {
+		pr_err("hisi  djtag init failed, ret=%d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+module_init(hisi_djtag_init);
+
+static void __exit hisi_djtag_exit(void)
+{
+	bus_unregister(&hisi_djtag_bus);
+}
+module_exit(hisi_djtag_exit);
+
+MODULE_DESCRIPTION("Hisilicon djtag driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("1.0");
diff --git a/drivers/perf/hisilicon/djtag.h b/drivers/perf/hisilicon/djtag.h
new file mode 100644
index 0000000..8a8471c
--- /dev/null
+++ b/drivers/perf/hisilicon/djtag.h
@@ -0,0 +1,47 @@
+/*
+ * Driver for Hisilicon djtag r/w via System Controller.
+ *
+ * Copyright (c) 2017 Hisilicon Limited
+ * Author: Tan Xiaojun <tanxiaojun@xxxxxxxxxx>
+ *         Anurup M <anurup.m@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __HISI_DJTAG_H
+#define __HISI_DJTAG_H
+
+#include <linux/bitops.h>
+#include <linux/device.h>
+
+#define DJTAG_CLIENT_NAME_LEN 32
+
+/* Get djtag instance or sub-module ID */
+#define DJTAG_GET_CHAIN_ID(x) (ilog2(x))
+
+struct hisi_djtag_client {
+	int id; /* Unique identifier to sufix in client->dev.name */
+	struct hisi_djtag_host *host;
+	struct list_head next;
+	struct device dev;
+};
+
+struct hisi_djtag_driver {
+	struct device_driver driver;
+	int (*probe)(struct hisi_djtag_client *);
+	int (*remove)(struct hisi_djtag_client *);
+};
+
+extern struct bus_type hisi_djtag_bus;
+
+int hisi_djtag_register_driver(struct module *owner,
+			       struct hisi_djtag_driver *driver);
+void hisi_djtag_unregister_driver(struct hisi_djtag_driver *driver);
+void hisi_djtag_readl(struct hisi_djtag_client *client, u32 offset,
+		      u32 mod_sel, int chain_id, u32 *val);
+void hisi_djtag_writel(struct hisi_djtag_client *client, u32 offset,
+		       u32 mod_sel, u32 mod_mask, u32 val);
+u32 hisi_djtag_get_sclid(struct hisi_djtag_client *client);
+#endif /* __HISI_DJTAG_H */
-- 
2.1.4