[patch v3 1/3] platform/mellanox: Introduce Mellanox hardware platform hotplug driver

[Vadim Pasternak]

It introduces mlxreg-hotplug driver with the generic regmap interface for
hardware access to the programmable device with interrupt controlling
logic. Where the programmable devices can be attached to different
interfaces types, like I2C, LPC, SPI.
Driver has been tested on systems based on x86 and ARM architectures.

Signed-off-by: Vadim Pasternak <vadimp@xxxxxxxxxxxx>
Acked-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
---
v2->v3:
 Fixes added by Vadim for kbuild test robot issue:
 - Disable of_update_property calls if COMPILE_TEST is configured in
   mlxreg-hotplug driver;
v1->v2:
 Fixes added by Vadim:
 - Add include/linux/platform_data/mlxreg.h, which was provided within
   another patch to this patch to allow kbuild testing.
---
 MAINTAINERS                                |   5 +
 drivers/platform/Kconfig                   |   2 +
 drivers/platform/Makefile                  |   1 +
 drivers/platform/mellanox/Kconfig          |  25 +
 drivers/platform/mellanox/Makefile         |   1 +
 drivers/platform/mellanox/mlxreg-hotplug.c | 712 +++++++++++++++++++++++++++++
 include/linux/platform_data/mlxreg.h       | 138 ++++++
 7 files changed, 884 insertions(+)
 create mode 100644 drivers/platform/mellanox/Kconfig
 create mode 100644 drivers/platform/mellanox/Makefile
 create mode 100644 drivers/platform/mellanox/mlxreg-hotplug.c
 create mode 100644 include/linux/platform_data/mlxreg.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 205d397..ccc7fa3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8544,6 +8544,11 @@ W:	http://www.mellanox.com
 Q:	http://patchwork.ozlabs.org/project/netdev/list/
 F:	drivers/net/ethernet/mellanox/mlxsw/
 
+MELLANOX HARDWARE PLATFORM SUPPORT
+M:	Vadim Pasternak <vadimp@xxxxxxxxxxxx>
+S:	Maintained
+F:	drivers/platform/mellanox/
+
 MELLANOX FIRMWARE FLASH LIBRARY (mlxfw)
 M:	Yotam Gigi <yotamg@xxxxxxxxxxxx>
 L:	netdev@xxxxxxxxxxxxxxx
diff --git a/drivers/platform/Kconfig b/drivers/platform/Kconfig
index c11db8b..d4c2e42 100644
--- a/drivers/platform/Kconfig
+++ b/drivers/platform/Kconfig
@@ -8,3 +8,5 @@ endif
 source "drivers/platform/goldfish/Kconfig"
 
 source "drivers/platform/chrome/Kconfig"
+
+source "drivers/platform/mellanox/Kconfig"
diff --git a/drivers/platform/Makefile b/drivers/platform/Makefile
index ca26925..bd87ce0 100644
--- a/drivers/platform/Makefile
+++ b/drivers/platform/Makefile
@@ -3,6 +3,7 @@
 #
 
 obj-$(CONFIG_X86)		+= x86/
+obj-$(CONFIG_MELLANOX_PLATFORM)	+= mellanox/
 obj-$(CONFIG_MIPS)		+= mips/
 obj-$(CONFIG_OLPC)		+= olpc/
 obj-$(CONFIG_GOLDFISH)		+= goldfish/
diff --git a/drivers/platform/mellanox/Kconfig b/drivers/platform/mellanox/Kconfig
new file mode 100644
index 0000000..6df0a56
--- /dev/null
+++ b/drivers/platform/mellanox/Kconfig
@@ -0,0 +1,25 @@
+#
+# Platform support for Mellanox hardware
+#
+
+menuconfig MELLANOX_PLATFORM
+	bool "Platform support for Mellanox hardware"
+	depends on (X86 && !OF) || ARM || COMPILE_TEST
+	---help---
+	  Say Y here to get to see options for platform support for
+	  Mellanox systems. This option alone does not add any kernel code.
+
+	  If you say N, all options in this submenu will be skipped and disabled.
+
+if MELLANOX_PLATFORM
+
+config MLXREG_HOTPLUG
+	tristate "Mellanox platform hotplug driver support"
+	depends on REGMAP
+	depends on HWMON
+	depends on I2C
+	---help---
+	  This driver handles hot-plug events for the power suppliers, power
+	  cables and fans on the wide range Mellanox IB and Ethernet systems.
+
+endif # MELLANOX_PLATFORM
diff --git a/drivers/platform/mellanox/Makefile b/drivers/platform/mellanox/Makefile
new file mode 100644
index 0000000..f58d089
--- /dev/null
+++ b/drivers/platform/mellanox/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_MLXREG_HOTPLUG)	+= mlxreg-hotplug.o
diff --git a/drivers/platform/mellanox/mlxreg-hotplug.c b/drivers/platform/mellanox/mlxreg-hotplug.c
new file mode 100644
index 0000000..69af730
--- /dev/null
+++ b/drivers/platform/mellanox/mlxreg-hotplug.c
@@ -0,0 +1,712 @@
+/*
+ * Copyright (c) 2017 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2017 Vadim Pasternak <vadimp@xxxxxxxxxxxx>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/gpio.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/interrupt.h>
+#include <linux/i2c.h>
+#include <linux/io.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_data/mlxreg.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+
+/* Offset of event and mask registers from status register. */
+#define MLXREG_HOTPLUG_EVENT_OFF	1
+#define MLXREG_HOTPLUG_MASK_OFF		2
+#define MLXREG_HOTPLUG_AGGR_MASK_OFF	1
+
+/* ASIC health parameters. */
+#define MLXREG_HOTPLUG_HEALTH_MASK	0x02
+#define MLXREG_HOTPLUG_RST_CNTR		3
+
+#define MLXREG_HOTPLUG_PROP_OKAY	"okay"
+#define MLXREG_HOTPLUG_PROP_DISABLED	"disabled"
+#define MLXREG_HOTPLUG_PROP_STATUS	"status"
+
+#define MLXREG_HOTPLUG_ATTRS_MAX	24
+
+/**
+ * struct mlxreg_hotplug_priv_data - platform private data:
+ * @irq: platform device interrupt number;
+ * @pdev: platform device;
+ * @plat: platform data;
+ * @dwork: delayed work template;
+ * @lock: spin lock;
+ * @hwmon: hwmon device;
+ * @mlxreg_hotplug_attr: sysfs attributes array;
+ * @mlxreg_hotplug_dev_attr: sysfs sensor device attribute array;
+ * @group: sysfs attribute group;
+ * @groups: list of sysfs attribute group for hwmon registration;
+ * @cell: location of top aggregation interrupt register;
+ * @mask: top aggregation interrupt common mask;
+ * @aggr_cache: last value of aggregation register status;
+ */
+struct mlxreg_hotplug_priv_data {
+	int irq;
+	struct device *dev;
+	struct platform_device *pdev;
+	struct mlxreg_hotplug_platform_data *plat;
+	struct regmap *regmap;
+	struct delayed_work dwork_irq;
+	struct delayed_work dwork;
+	spinlock_t lock; /* sync with interrupt */
+	struct device *hwmon;
+	struct attribute *mlxreg_hotplug_attr[MLXREG_HOTPLUG_ATTRS_MAX + 1];
+	struct sensor_device_attribute_2
+			mlxreg_hotplug_dev_attr[MLXREG_HOTPLUG_ATTRS_MAX];
+	struct attribute_group group;
+	const struct attribute_group *groups[2];
+	u32 cell;
+	u32 mask;
+	u32 aggr_cache;
+	bool after_probe;
+};
+
+#if defined(CONFIG_OF) && !defined(CONFIG_COMPILE_TEST)
+/**
+ * struct mlxreg_hotplug_device_en - Open Firmware property for enabling device
+ *
+ * @name - property name;
+ * @value - property value string;
+ * @length - length of proprty value string;
+ *
+ * The structure is used for the devices, which require some dynamic
+ * selection operation allowing access to them.
+ */
+static struct property mlxreg_hotplug_device_en = {
+	.name = MLXREG_HOTPLUG_PROP_STATUS,
+	.value = MLXREG_HOTPLUG_PROP_OKAY,
+	.length = sizeof(MLXREG_HOTPLUG_PROP_OKAY),
+};
+
+/**
+ * struct mlxreg_hotplug_device_dis - Open Firmware property for disabling
+ * device
+ *
+ * @name - property name;
+ * @value - property value string;
+ * @length - length of proprty value string;
+ *
+ * The structure is used for the devices, which require some dynamic
+ * selection operation disallowing access to them.
+ */
+static struct property mlxreg_hotplug_device_dis = {
+	.name = MLXREG_HOTPLUG_PROP_STATUS,
+	.value = MLXREG_HOTPLUG_PROP_DISABLED,
+	.length = sizeof(MLXREG_HOTPLUG_PROP_DISABLED),
+};
+
+static int mlxreg_hotplug_of_device_create(struct mlxreg_core_data *data)
+{
+	return of_update_property(data->np, &mlxreg_hotplug_device_en);
+}
+
+static void mlxreg_hotplug_of_device_destroy(struct mlxreg_core_data *data)
+{
+	of_update_property(data->np, &mlxreg_hotplug_device_dis);
+	of_node_clear_flag(data->np, OF_POPULATED);
+}
+#else
+static int mlxreg_hotplug_of_device_create(struct mlxreg_core_data *data)
+{
+	return 0;
+}
+
+static void mlxreg_hotplug_of_device_destroy(struct mlxreg_core_data *data)
+{
+}
+#endif
+
+static int mlxreg_hotplug_device_create(struct mlxreg_core_data *data)
+{
+	data->hpdev.adapter = i2c_get_adapter(data->hpdev.nr);
+	if (!data->hpdev.adapter)
+		return -EFAULT;
+
+	data->hpdev.client = i2c_new_device(data->hpdev.adapter,
+					    data->hpdev.brdinfo);
+	if (!data->hpdev.client) {
+		i2c_put_adapter(data->hpdev.adapter);
+		data->hpdev.adapter = NULL;
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
+static void mlxreg_hotplug_device_destroy(struct mlxreg_core_data *data)
+{
+	if (data->hpdev.client) {
+		i2c_unregister_device(data->hpdev.client);
+		data->hpdev.client = NULL;
+	}
+
+	if (data->hpdev.adapter) {
+		i2c_put_adapter(data->hpdev.adapter);
+		data->hpdev.adapter = NULL;
+	}
+}
+
+static int mlxreg_hotplug_dev_enable(struct mlxreg_core_data *data)
+{
+	int err;
+
+	/* Enable and create device. */
+	if (data->np)
+		err = mlxreg_hotplug_of_device_create(data);
+	else
+		err = mlxreg_hotplug_device_create(data);
+
+	return err;
+}
+
+static void mlxreg_hotplug_dev_disable(struct mlxreg_core_data *data)
+{
+	/* Disable and unregister platform device. */
+	if (data->np)
+		mlxreg_hotplug_of_device_destroy(data);
+	else
+		mlxreg_hotplug_device_destroy(data);
+}
+
+static ssize_t mlxreg_hotplug_attr_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct mlxreg_hotplug_priv_data *priv = dev_get_drvdata(dev);
+	struct mlxreg_core_hotplug_platform_data *pdata;
+	int index = to_sensor_dev_attr_2(attr)->index;
+	int nr = to_sensor_dev_attr_2(attr)->nr;
+	struct mlxreg_core_item *item;
+	struct mlxreg_core_data *data;
+	u32 regval;
+	int ret;
+
+	pdata = dev_get_platdata(&priv->pdev->dev);
+	item = pdata->items + nr;
+	data = item->data + index;
+
+	ret = regmap_read(priv->regmap, data->reg, &regval);
+	if (ret)
+		return ret;
+
+	if (item->health) {
+		regval &= data->mask;
+	} else {
+		/* Bit = 0 : functional if item->inversed is true. */
+		if (item->inversed)
+			regval = !(regval & data->mask);
+		else
+			regval = !!(regval & data->mask);
+	}
+
+	return sprintf(buf, "%u\n", regval);
+}
+
+static int
+mlxreg_hotplug_attr_init(struct mlxreg_hotplug_priv_data *priv)
+{
+	struct mlxreg_core_hotplug_platform_data *pdata;
+	struct mlxreg_core_item *item;
+	struct mlxreg_core_data *data;
+	int num_attrs = 0, id = 0, i, j;
+
+	pdata = dev_get_platdata(&priv->pdev->dev);
+	item = pdata->items;
+
+	for (i = 0; i < pdata->counter; i++)
+		num_attrs += (item + i)->count;
+
+	priv->group.attrs = devm_kzalloc(&priv->pdev->dev, num_attrs *
+					 sizeof(struct attribute *),
+					 GFP_KERNEL);
+	if (!priv->group.attrs)
+		return -ENOMEM;
+
+	for (i = 0; i < pdata->counter; i++, item++) {
+		data = item->data;
+		for (j = 0; j < item->count; j++, data++, id++) {
+			priv->mlxreg_hotplug_attr[id] =
+			&priv->mlxreg_hotplug_dev_attr[id].dev_attr.attr;
+			priv->mlxreg_hotplug_attr[id]->name =
+				devm_kasprintf(&priv->pdev->dev, GFP_KERNEL,
+					       data->label);
+
+			if (!priv->mlxreg_hotplug_attr[id]->name) {
+				dev_err(priv->dev, "Memory allocation failed for attr %d.\n",
+					id);
+				return -ENOMEM;
+			}
+
+			priv->mlxreg_hotplug_dev_attr[id].dev_attr.attr.mode =
+									0444;
+			priv->mlxreg_hotplug_dev_attr[id].dev_attr.show =
+						mlxreg_hotplug_attr_show;
+			priv->mlxreg_hotplug_dev_attr[id].nr = i;
+			priv->mlxreg_hotplug_dev_attr[id].index = j;
+			sysfs_attr_init(
+			&priv->mlxreg_hotplug_dev_attr[id].dev_attr.attr);
+		}
+	}
+
+	priv->group.attrs = priv->mlxreg_hotplug_attr;
+	priv->groups[0] = &priv->group;
+	priv->groups[1] = NULL;
+
+	return 0;
+}
+
+static void
+mlxreg_hotplug_work_helper(struct mlxreg_hotplug_priv_data *priv,
+			   struct mlxreg_core_item *item)
+{
+	struct mlxreg_core_data *data;
+	u32 asserted, regval, bit;
+	int ret;
+
+	/*
+	 * Validate if item related to received signal type is valid.
+	 * It should never happen, excepted the situation when some
+	 * piece of hardware is broken. In such situation just produce
+	 * error message and return. Caller must continue to handle the
+	 * signals from other devices if any.
+	 */
+	if (unlikely(!item)) {
+		dev_err(priv->dev, "False signal: at offset:mask 0x%02x:0x%02x.\n",
+			item->reg, item->mask);
+
+		return;
+	}
+
+	/* Mask event. */
+	ret = regmap_write(priv->regmap, item->reg + MLXREG_HOTPLUG_MASK_OFF,
+			   0);
+	if (ret)
+		goto access_error;
+
+	/* Read status. */
+	ret = regmap_read(priv->regmap, item->reg, &regval);
+	if (ret)
+		goto access_error;
+
+	/* Set asserted bits and save last status. */
+	regval &= item->mask;
+	asserted = item->cache ^ regval;
+	item->cache = regval;
+
+	for_each_set_bit(bit, (unsigned long *)&asserted, 8) {
+		data = item->data + bit;
+		if (regval & BIT(bit)) {
+			if (item->inversed)
+				mlxreg_hotplug_dev_disable(data);
+			else
+				mlxreg_hotplug_dev_enable(data);
+		} else {
+			if (item->inversed)
+				mlxreg_hotplug_dev_enable(data);
+			else
+				mlxreg_hotplug_dev_disable(data);
+		}
+	}
+
+	/* Acknowledge event. */
+	ret = regmap_write(priv->regmap, item->reg + MLXREG_HOTPLUG_EVENT_OFF,
+			   0);
+	if (ret)
+		goto access_error;
+
+	/* Unmask event. */
+	ret = regmap_write(priv->regmap, item->reg + MLXREG_HOTPLUG_MASK_OFF,
+			   item->mask);
+	if (ret)
+		goto access_error;
+
+	return;
+
+access_error:
+	dev_err(priv->dev, "Failed to complete workqueue.\n");
+}
+
+static void
+mlxreg_hotplug_health_work_helper(struct mlxreg_hotplug_priv_data *priv,
+				  struct mlxreg_core_item *item)
+{
+	struct mlxreg_core_data *data = item->data;
+	u32 regval;
+	int i, ret;
+
+	for (i = 0; i < item->count; i++, data++) {
+		/* Mask event. */
+		ret = regmap_write(priv->regmap, data->reg +
+				   MLXREG_HOTPLUG_MASK_OFF, 0);
+		if (ret)
+			goto access_error;
+
+		/* Read status. */
+		ret = regmap_read(priv->regmap, data->reg, &regval);
+		if (ret)
+			goto access_error;
+
+		regval &= data->mask;
+		item->cache = regval;
+		if (regval == MLXREG_HOTPLUG_HEALTH_MASK) {
+			if ((data->health_cntr++ == MLXREG_HOTPLUG_RST_CNTR) ||
+			    !priv->after_probe) {
+				mlxreg_hotplug_dev_enable(data);
+				data->attached = true;
+			}
+		} else {
+			if (data->attached) {
+				mlxreg_hotplug_dev_disable(data);
+				data->attached = false;
+				data->health_cntr = 0;
+			}
+		}
+
+		/* Acknowledge event. */
+		ret = regmap_write(priv->regmap, data->reg +
+				   MLXREG_HOTPLUG_EVENT_OFF, 0);
+		if (ret)
+			goto access_error;
+
+		/* Unmask event. */
+		ret = regmap_write(priv->regmap, data->reg +
+				   MLXREG_HOTPLUG_MASK_OFF, data->mask);
+		if (ret)
+			goto access_error;
+	}
+
+	return;
+
+access_error:
+	dev_err(priv->dev, "Failed to complete workqueue.\n");
+}
+
+/*
+ * mlxreg_hotplug_work_handler - performs traversing of device interrupt
+ * registers according to the below hierarchy schema:
+ *
+ *				Aggregation registers (status/mask)
+ * PSU registers:		*---*
+ * *-----------------*		|   |
+ * |status/event/mask|----->    | * |
+ * *-----------------*		|   |
+ * Power registers:		|   |
+ * *-----------------*		|   |
+ * |status/event/mask|----->    | * |
+ * *-----------------*		|   |
+ * FAN registers:		|   |--> CPU
+ * *-----------------*		|   |
+ * |status/event/mask|----->    | * |
+ * *-----------------*		|   |
+ * ASIC registers:		|   |
+ * *-----------------*		|   |
+ * |status/event/mask|----->    | * |
+ * *-----------------*		|   |
+ *				*---*
+ *
+ * In case some system changed are detected: FAN in/out, PSU in/out, power
+ * cable attached/detached, ASIC helath good/bad, relevant device is created
+ * or destroyed.
+ */
+static void mlxreg_hotplug_work_handler(struct work_struct *work)
+{
+	struct mlxreg_hotplug_priv_data *priv = container_of(work,
+			struct mlxreg_hotplug_priv_data, dwork_irq.work);
+	struct mlxreg_core_hotplug_platform_data *pdata;
+	struct mlxreg_core_item *item;
+	unsigned long flags;
+	u32 regval, aggr_asserted;
+	int i;
+	int ret;
+
+	pdata = dev_get_platdata(&priv->pdev->dev);
+	item = pdata->items;
+	/* Mask aggregation event. */
+	ret = regmap_write(priv->regmap, pdata->cell +
+			   MLXREG_HOTPLUG_AGGR_MASK_OFF, 0);
+	if (ret < 0)
+		goto access_error;
+
+	/* Read aggregation status. */
+	ret = regmap_read(priv->regmap, pdata->cell, &regval);
+	if (ret)
+		goto access_error;
+
+	regval &= pdata->mask;
+	aggr_asserted = priv->aggr_cache ^ regval;
+	priv->aggr_cache = regval;
+
+	/* Handle topology and health configuration changes. */
+	for (i = 0; i < pdata->counter; i++, item++) {
+		if (aggr_asserted & item->aggr_mask) {
+			if (item->health)
+				mlxreg_hotplug_health_work_helper(priv, item);
+			else
+				mlxreg_hotplug_work_helper(priv, item);
+		}
+	}
+
+	if (aggr_asserted) {
+		spin_lock_irqsave(&priv->lock, flags);
+
+		/*
+		 * It is possible, that some signals have been inserted, while
+		 * interrupt has been masked by mlxreg_hotplug_work_handler.
+		 * In this case such signals will be missed. In order to handle
+		 * these signals delayed work is canceled and work task
+		 * re-scheduled for immediate execution. It allows to handle
+		 * missed signals, if any. In other case work handler just
+		 * validates that no new signals have been received during
+		 * masking.
+		 */
+		cancel_delayed_work(&priv->dwork_irq);
+		schedule_delayed_work(&priv->dwork_irq, 0);
+
+		spin_unlock_irqrestore(&priv->lock, flags);
+
+		return;
+	}
+
+	/* Unmask aggregation event (no need acknowledge). */
+	ret = regmap_write(priv->regmap, pdata->cell +
+			   MLXREG_HOTPLUG_AGGR_MASK_OFF, pdata->mask);
+	if (ret)
+		goto access_error;
+
+	return;
+
+access_error:
+	dev_err(priv->dev, "Failed to complete workqueue.\n");
+}
+
+static int mlxreg_hotplug_set_irq(struct mlxreg_hotplug_priv_data *priv)
+{
+	struct mlxreg_core_hotplug_platform_data *pdata;
+	struct mlxreg_core_item *item;
+	int i;
+	int ret;
+
+	pdata = dev_get_platdata(&priv->pdev->dev);
+	item = pdata->items;
+
+	for (i = 0; i < pdata->counter; i++, item++) {
+		/* Clear group presense event. */
+		ret = regmap_write(priv->regmap, item->reg +
+				   MLXREG_HOTPLUG_EVENT_OFF, 0);
+		if (ret)
+			goto access_error;
+
+		/* Set group initial status as mask and unmask group event. */
+		if (item->inversed) {
+			item->cache = item->mask;
+			ret = regmap_write(priv->regmap, item->reg +
+					   MLXREG_HOTPLUG_MASK_OFF,
+					   item->mask);
+			if (ret)
+				goto access_error;
+		}
+	}
+
+	/* Keep aggregation initial status as zero and unmask events. */
+	ret = regmap_write(priv->regmap, pdata->cell +
+			   MLXREG_HOTPLUG_AGGR_MASK_OFF, pdata->mask);
+	if (ret)
+		goto access_error;
+
+	/* Invoke work handler for initializing hot plug devices setting. */
+	mlxreg_hotplug_work_handler(&priv->dwork_irq.work);
+
+	enable_irq(priv->irq);
+
+	return 0;
+
+access_error:
+	dev_err(priv->dev, "Failed to set interrupts.\n");
+
+	enable_irq(priv->irq);
+
+	return ret;
+}
+
+static void mlxreg_hotplug_unset_irq(struct mlxreg_hotplug_priv_data *priv)
+{
+	struct mlxreg_core_hotplug_platform_data *pdata;
+	struct mlxreg_core_item *item;
+	struct mlxreg_core_data *data;
+	int count, i, j;
+
+	pdata = dev_get_platdata(&priv->pdev->dev);
+	item = pdata->items;
+	disable_irq(priv->irq);
+	cancel_delayed_work_sync(&priv->dwork_irq);
+
+	/* Mask aggregation event. */
+	regmap_write(priv->regmap, pdata->cell + MLXREG_HOTPLUG_AGGR_MASK_OFF,
+		     0);
+
+	/* Clear topology configurations. */
+	for (i = 0; i < pdata->counter; i++, item++) {
+		data = item->data;
+		/* Mask group presense event. */
+		regmap_write(priv->regmap, data->reg + MLXREG_HOTPLUG_MASK_OFF,
+			     0);
+		/* Clear group presense event. */
+		regmap_write(priv->regmap, data->reg +
+			     MLXREG_HOTPLUG_EVENT_OFF, 0);
+
+		/* Remove all the attached devices in group. */
+		count = item->count;
+		for (j = 0; j < count; j++, data++)
+			mlxreg_hotplug_dev_disable(data);
+	}
+}
+
+static irqreturn_t mlxreg_hotplug_irq_handler(int irq, void *dev)
+{
+	struct mlxreg_hotplug_priv_data *priv =
+				(struct mlxreg_hotplug_priv_data *)dev;
+
+	/* Schedule work task for immediate execution.*/
+	schedule_delayed_work(&priv->dwork_irq, 0);
+
+	return IRQ_HANDLED;
+}
+
+static int mlxreg_hotplug_probe(struct platform_device *pdev)
+{
+	struct mlxreg_core_hotplug_platform_data *pdata;
+	struct mlxreg_hotplug_priv_data *priv;
+	int err;
+
+	pdata = dev_get_platdata(&pdev->dev);
+	if (!pdata) {
+		dev_err(&pdev->dev, "Failed to get platform data.\n");
+		return -EINVAL;
+	}
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	if (pdata->irq) {
+		priv->irq = pdata->irq;
+	} else {
+		priv->irq = platform_get_irq(pdev, 0);
+		if (priv->irq < 0) {
+			dev_err(&pdev->dev, "Failed to get platform irq: %d\n",
+				priv->irq);
+			return priv->irq;
+		}
+	}
+
+	priv->regmap = pdata->regmap;
+	priv->dev = pdev->dev.parent;
+	priv->pdev = pdev;
+
+	err = devm_request_irq(&pdev->dev, priv->irq,
+			       mlxreg_hotplug_irq_handler, IRQF_TRIGGER_FALLING
+			       | IRQF_SHARED, "mlxreg-hotplug", priv);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to request irq: %d\n", err);
+		return err;
+	}
+
+	disable_irq(priv->irq);
+	spin_lock_init(&priv->lock);
+	INIT_DELAYED_WORK(&priv->dwork_irq, mlxreg_hotplug_work_handler);
+	/* Perform initial interrupts setup. */
+	mlxreg_hotplug_set_irq(priv);
+
+	priv->after_probe = true;
+	dev_set_drvdata(&pdev->dev, priv);
+
+	err = mlxreg_hotplug_attr_init(priv);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to allocate attributes: %d\n",
+			err);
+		return err;
+	}
+
+	priv->hwmon = devm_hwmon_device_register_with_groups(&pdev->dev,
+					"mlxreg_hotplug", priv, priv->groups);
+	if (IS_ERR(priv->hwmon)) {
+		dev_err(&pdev->dev, "Failed to register hwmon device %ld\n",
+			PTR_ERR(priv->hwmon));
+		return PTR_ERR(priv->hwmon);
+	}
+
+	return 0;
+}
+
+static int mlxreg_hotplug_remove(struct platform_device *pdev)
+{
+	struct mlxreg_hotplug_priv_data *priv = dev_get_drvdata(&pdev->dev);
+
+	/* Clean interrupts setup. */
+	mlxreg_hotplug_unset_irq(priv);
+
+	return 0;
+}
+
+#if defined(CONFIG_OF)
+static const struct of_device_id mlxreg_hotplug_dt_match[] = {
+	{ .compatible = "mellanox,mlxreg-hotplug" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, mlxreg_hotplug_dt_match);
+#endif
+
+static struct platform_driver mlxreg_hotplug_driver = {
+	.driver = {
+	    .name = "mlxreg-hotplug",
+	    .of_match_table = of_match_ptr(mlxreg_hotplug_dt_match),
+	},
+	.probe = mlxreg_hotplug_probe,
+	.remove = mlxreg_hotplug_remove,
+};
+
+module_platform_driver(mlxreg_hotplug_driver);
+
+MODULE_AUTHOR("Vadim Pasternak <vadimp@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Mellanox regmap hotplug platform driver");
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_ALIAS("platform:mlxreg-hotplug");
diff --git a/include/linux/platform_data/mlxreg.h b/include/linux/platform_data/mlxreg.h
new file mode 100644
index 0000000..456b805
--- /dev/null
+++ b/include/linux/platform_data/mlxreg.h
@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) 2017 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2017 Vadim Pasternak <vadimp@xxxxxxxxxxxx>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __LINUX_PLATFORM_DATA_MLXREG_H
+#define __LINUX_PLATFORM_DATA_MLXREG_H
+
+#define MLXREG_CORE_LABEL_MAX_SIZE	32
+
+/**
+ * struct mlxreg_hotplug_device - I2C device data:
+ *
+ * @adapter: I2C device adapter;
+ * @client: I2C device client;
+ * @brdinfo: device board information;
+ * @nr: I2C device adapter number, to which device is to be attached;
+ *
+ * Structure represents I2C hotplug device static data (board topology) and
+ * dynamic data (related kernel objects handles).
+ */
+struct mlxreg_hotplug_device {
+	struct i2c_adapter *adapter;
+	struct i2c_client *client;
+	struct i2c_board_info *brdinfo;
+	int nr;
+};
+
+/**
+ * struct mlxreg_core_data - attributes control data:
+ *
+ * @label: attribute label;
+ * @label: attribute register offset;
+ * @reg: attribute register;
+ * @mask: attribute access mask;
+ * @bit: attribute effective bit;
+ * @np - pointer to node platform associated with attribute;
+ * @hpdev - hotplug device data;
+ * @health_cntr: dynamic device health indication counter;
+ * @attached: true if device has been attached after good helath indication;
+ */
+struct mlxreg_core_data {
+	char label[MLXREG_CORE_LABEL_MAX_SIZE];
+	u32 reg;
+	u32 mask;
+	u32 bit;
+	struct device_node *np;
+	struct mlxreg_hotplug_device hpdev;
+	u8 health_cntr;
+	bool attached;
+};
+
+/**
+ * struct mlxreg_core_item - same type components controlled by the driver:
+ *
+ * @data: component data;
+ * @aggr_mask: group aggregation mask;
+ * @reg: group interrupt status register;
+ * @mask: group interrupt mask;
+ * @cache: last status value for elements fro the same group;
+ * @count: number of available elements in the group;
+ * @ind: element's index inside the group;
+ * @inversed: if 0: 0 for signal status is OK, if 1 - 1 is OK;
+ * @health: true if device has health indication, false in other case;
+ */
+struct mlxreg_core_item {
+	struct mlxreg_core_data *data;
+	u32 aggr_mask;
+	u32 reg;
+	u32 mask;
+	u32 cache;
+	u8 count;
+	u8 ind;
+	u8 inversed;
+	u8 health;
+};
+
+/**
+ * struct mlxreg_core_led_platform_data - led platform data:
+ *
+ * @led_data: led private data;
+ * @regmap: register map of parent device;
+ * @counter: number of led instances;
+ */
+struct mlxreg_core_led_platform_data {
+	struct mlxreg_core_data *data;
+	void *regmap;
+	int counter;
+};
+
+/**
+ * struct mlxreg_core_hotplug_platform_data - hotplug platform data:
+ *
+ * @items: same type components with the hotplug capability;
+ * @irq: platform interrupt number;
+ * @regmap: register map of parent device;
+ * @counter: number of the components with the hotplug capability;
+ * @cell: location of top aggregation interrupt register;
+ * @mask: top aggregation interrupt common mask;
+ */
+struct mlxreg_core_hotplug_platform_data {
+	struct mlxreg_core_item *items;
+	int irq;
+	void *regmap;
+	int counter;
+	u32 cell;
+	u32 mask;
+};
+
+#endif /* __LINUX_PLATFORM_DATA_MLXREG_H */
-- 
2.1.4