Message-Id: <1476980881-62938-1-git-send-email-vadimp@mellanox.com>
Date:   Thu, 20 Oct 2016 16:28:01 +0000
From:   vadimp@...lanox.com
To:     dvhart@...radead.org
Cc:     davem@...emloft.net, geert@...ux-m68k.org,
        akpm@...ux-foundation.org, kvalo@...eaurora.org,
        gregkh@...uxfoundation.org, mchehab@...nel.org, linux@...ck-us.net,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        jiri@...nulli.us, Vadim Pasternak <vadimp@...lanox.com>
Subject: [patch v3] drivers/platform/x86: introduce support for Mellanox hotplug driver

From: Vadim Pasternak <vadimp@...lanox.com>

Enable system support for the Mellanox Technologies hotplug platform
driver, which provides support for the next Mellanox basic systems:
"msx6710", "msx6720", "msb7700", "msn2700", "msx1410", "msn2410",
"msb7800", "msn2740", "msn2100" and also various number of derivative
systems from the above basic types.
This driver handles hot-plug events for the power suppliers, power
cables and fans for the above systems.

The Kconfig currently controlling compilation of this code is:
driver/platform/x86:config MLX_CPLD_PLATFORM
                       tristate "Mellanox platform hotplug driver support"

Signed-off-by: Vadim Pasternak <vadimp@...lanox.com>
---
v1->v2:
 Comments pointed out by Darren:
 - remove whitespaces in config;
 - remove redundant includes for header files;
 - fix comments styling;
 - fix register value assignment in mlxcpld_hotplug_attr_show;
 - mlxcpld_hotplug_attr_init - use local aliases to reduce line length;
 - Add fields description in the struct mlxcpld_hotplug_device;
v2->v3:
 Comments pointed out by Darren:
  - Fix structures and enum comments in mlxcpld-hotplug.c according to
    Documentation/kernel-documentation.rst guideline;
  - Assign and mask aggregation status in mlxcpld_hotplug_work_handler on
    the same line.
  - Refactor mlxcpld_hotplug_work_handler. Make common helper routine for
    each attribute type.
  - Produce error message in case signal is not expected.
  - Fix header file according to Documentation/kernel-documentation.rst
    guideline;
 Fix added by Vadim:
	Fix re-scheduling flow for possibly missed signals. By mistake it
	was coupled with FAN.
---
 MAINTAINERS                                   |   7 +
 drivers/platform/x86/Kconfig                  |  10 +
 drivers/platform/x86/Makefile                 |   1 +
 drivers/platform/x86/mlxcpld-hotplug.c        | 515 ++++++++++++++++++++++++++
 include/linux/platform_data/mlxcpld-hotplug.h |  99 +++++
 5 files changed, 632 insertions(+)
 create mode 100644 drivers/platform/x86/mlxcpld-hotplug.c
 create mode 100644 include/linux/platform_data/mlxcpld-hotplug.h

diff --git a/MAINTAINERS b/MAINTAINERS
index a306795..cbfe2a8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7649,6 +7649,13 @@ W:	http://www.mellanox.com
 Q:	http://patchwork.ozlabs.org/project/netdev/list/
 F:	drivers/net/ethernet/mellanox/mlxsw/
 
+MELLANOX MLX CPLD HOTPLUG DRIVER
+M:	Vadim Pasternak <vadimp@...lanox.com>
+L:	platform-driver-x86@...r.kernel.org
+S:	Supported
+F:	drivers/platform/x86/mlxcpld-hotplug.c
+F:	include/linux/platform_data/mlxcpld-hotplug.h
+
 SOFT-ROCE DRIVER (rxe)
 M:	Moni Shoua <monis@...lanox.com>
 L:	linux-rdma@...r.kernel.org
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 81b8dcc..c92e2f8 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -1026,4 +1026,14 @@ config INTEL_TELEMETRY
 	  used to get various SoC events and parameters
 	  directly via debugfs files. Various tools may use
 	  this interface for SoC state monitoring.
+
+config MLX_CPLD_PLATFORM
+	tristate "Mellanox platform hotplug driver support"
+	default n
+	depends on MLX_PLATFORM
+	select 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 # X86_PLATFORM_DEVICES
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 2efa86d..1f06b63 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -71,3 +71,4 @@ obj-$(CONFIG_INTEL_TELEMETRY)	+= intel_telemetry_core.o \
 				   intel_telemetry_pltdrv.o \
 				   intel_telemetry_debugfs.o
 obj-$(CONFIG_INTEL_PMC_CORE)    += intel_pmc_core.o
+obj-$(CONFIG_MLX_CPLD_PLATFORM)	+= mlxcpld-hotplug.o
diff --git a/drivers/platform/x86/mlxcpld-hotplug.c b/drivers/platform/x86/mlxcpld-hotplug.c
new file mode 100644
index 0000000..aff3686
--- /dev/null
+++ b/drivers/platform/x86/mlxcpld-hotplug.c
@@ -0,0 +1,515 @@
+/*
+ * drivers/platform/x86/mlxcpld-hotplug.c
+ * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2016 Vadim Pasternak <vadimp@...lanox.com>
+ *
+ * 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/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_data/mlxcpld-hotplug.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+
+/* Offset of event and mask registers from status register */
+#define MLXCPLD_HOTPLUG_EVENT_OFF	1
+#define MLXCPLD_HOTPLUG_MASK_OFF	2
+#define MLXCPLD_HOTPLUG_AGGR_MASK_OFF	1
+
+#define MLXCPLD_HOTPLUG_ATTRS_NUM	8
+
+/**
+ * enum mlxcpld_hotplug_attr_type - sysfs attributes for hotplug events:
+ * @MLXCPLD_HOTPLUG_ATTR_TYPE_PSU: power supply unit attribute;
+ * @MLXCPLD_HOTPLUG_ATTR_TYPE_PWR: power cable attribute;
+ * @MLXCPLD_HOTPLUG_ATTR_TYPE_FAN: FAN drawer attribute;
+ */
+enum mlxcpld_hotplug_attr_type {
+	MLXCPLD_HOTPLUG_ATTR_TYPE_PSU,
+	MLXCPLD_HOTPLUG_ATTR_TYPE_PWR,
+	MLXCPLD_HOTPLUG_ATTR_TYPE_FAN,
+};
+
+/**
+ * struct mlxcpld_hotplug_priv_data - platform private data:
+ * @irq: platform interrupt number;
+ * @pdev: platform device;
+ * @plat: platform data;
+ * @hwmon: hwmon device;
+ * @mlxcpld_hotplug_attr: sysfs attributes array;
+ * @mlxcpld_hotplug_dev_attr: sysfs sensor device attribute array;
+ * @group: sysfs attribute group;
+ * @groups: list of sysfs attribute group for hwmon registration;
+ * @dwork: delayed work template;
+ * @lock: spin lock;
+ * @aggr_cache: last value of aggregation register status;
+ * @psu_cache: last value of PSU register status;
+ * @pwr_cache: last value of power register status;
+ * @fan_cache: last value of FAN register status;
+ */
+struct mlxcpld_hotplug_priv_data {
+	int irq;
+	struct platform_device *pdev;
+	struct mlxcpld_hotplug_platform_data *plat;
+	struct device *hwmon;
+	struct attribute *mlxcpld_hotplug_attr[MLXCPLD_HOTPLUG_ATTRS_NUM + 1];
+	struct sensor_device_attribute_2
+			mlxcpld_hotplug_dev_attr[MLXCPLD_HOTPLUG_ATTRS_NUM];
+	struct attribute_group group;
+	const struct attribute_group *groups[2];
+	struct delayed_work dwork;
+	spinlock_t lock;
+	u8 aggr_cache;
+	u8 psu_cache;
+	u8 pwr_cache;
+	u8 fan_cache;
+};
+
+static ssize_t mlxcpld_hotplug_attr_show(struct device *dev,
+					 struct device_attribute *attr,
+					 char *buf)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct mlxcpld_hotplug_priv_data *priv = platform_get_drvdata(pdev);
+	int index = to_sensor_dev_attr_2(attr)->index;
+	int nr = to_sensor_dev_attr_2(attr)->nr;
+	u8 reg_val = 0;
+
+	switch (nr) {
+	case MLXCPLD_HOTPLUG_ATTR_TYPE_PSU:
+		/* Bit = 0 : PSU is present. */
+		reg_val = !!!(inb(priv->plat->psu_reg_offset) & BIT(index));
+		break;
+
+	case MLXCPLD_HOTPLUG_ATTR_TYPE_PWR:
+		/* Bit = 1 : power cable is attached. */
+		reg_val = !!(inb(priv->plat->pwr_reg_offset) & BIT(index %
+						priv->plat->pwr_count));
+		break;
+
+	case MLXCPLD_HOTPLUG_ATTR_TYPE_FAN:
+		/* Bit = 0 : FAN is present. */
+		reg_val = !!!(inb(priv->plat->fan_reg_offset) & BIT(index %
+						priv->plat->fan_count));
+		break;
+	}
+
+	return sprintf(buf, "%u\n", reg_val);
+}
+
+#define PRIV_ATTR(i) priv->mlxcpld_hotplug_attr[i]
+#define PRIV_DEV_ATTR(i) priv->mlxcpld_hotplug_dev_attr[i]
+static int mlxcpld_hotplug_attr_init(struct mlxcpld_hotplug_priv_data *priv)
+{
+	int num_attrs = priv->plat->psu_count + priv->plat->pwr_count +
+			priv->plat->fan_count;
+	int i;
+
+	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 < num_attrs; i++) {
+		PRIV_ATTR(i) = &PRIV_DEV_ATTR(i).dev_attr.attr;
+
+		if (i < priv->plat->psu_count) {
+			PRIV_ATTR(i)->name = devm_kasprintf(&priv->pdev->dev,
+						GFP_KERNEL, "psu%u", i + 1);
+			PRIV_DEV_ATTR(i).nr = MLXCPLD_HOTPLUG_ATTR_TYPE_PSU;
+		} else if (i < priv->plat->psu_count + priv->plat->pwr_count) {
+			PRIV_ATTR(i)->name = devm_kasprintf(&priv->pdev->dev,
+						GFP_KERNEL, "pwr%u", i %
+						priv->plat->pwr_count + 1);
+			PRIV_DEV_ATTR(i).nr = MLXCPLD_HOTPLUG_ATTR_TYPE_PWR;
+		} else {
+			PRIV_ATTR(i)->name = devm_kasprintf(&priv->pdev->dev,
+						GFP_KERNEL, "fan%u", i %
+						priv->plat->fan_count + 1);
+			PRIV_DEV_ATTR(i).nr = MLXCPLD_HOTPLUG_ATTR_TYPE_FAN;
+		}
+
+		if (!PRIV_ATTR(i)->name) {
+			dev_err(&priv->pdev->dev, "Memory allocation failed for sysfs attribute %d.\n",
+				i + 1);
+			return -ENOMEM;
+		}
+
+		PRIV_DEV_ATTR(i).dev_attr.attr.name = PRIV_ATTR(i)->name;
+		PRIV_DEV_ATTR(i).dev_attr.attr.mode = S_IRUGO;
+		PRIV_DEV_ATTR(i).dev_attr.show = mlxcpld_hotplug_attr_show;
+		PRIV_DEV_ATTR(i).index = i;
+		sysfs_attr_init(&PRIV_DEV_ATTR(i).dev_attr.attr);
+	}
+
+	priv->group.attrs = priv->mlxcpld_hotplug_attr;
+	priv->groups[0] = &priv->group;
+	priv->groups[1] = NULL;
+
+	return 0;
+}
+
+static int mlxcpld_hotplug_device_create(struct device *dev,
+					 struct mlxcpld_hotplug_device *item)
+{
+	item->adapter = i2c_get_adapter(item->bus);
+	if (!item->adapter) {
+		dev_err(dev, "Failed to get adapter for bus %d\n",
+			item->bus);
+		return -EFAULT;
+	}
+
+	item->client = i2c_new_device(item->adapter, &item->brdinfo);
+	if (!item->client) {
+		dev_err(dev, "Failed to create client %s at bus %d at addr 0x%02x\n",
+			item->brdinfo.type, item->bus, item->brdinfo.addr);
+		i2c_put_adapter(item->adapter);
+		item->adapter = NULL;
+		return -EFAULT;
+	}
+
+	return 0;
+}
+
+static void mlxcpld_hotplug_device_destroy(struct mlxcpld_hotplug_device *item)
+{
+	if (item->client) {
+		i2c_unregister_device(item->client);
+		item->client = NULL;
+	}
+
+	if (item->adapter) {
+		i2c_put_adapter(item->adapter);
+		item->adapter = NULL;
+	}
+}
+
+static inline void
+mlxcpld_hotplug_work_helper(struct device *dev,
+			    struct mlxcpld_hotplug_device *item, u8 is_inverse,
+			    u16 offset, u8 mask, u8 *cache)
+{
+	u8 val, asserted;
+	int bit;
+
+	/* Mask event. */
+	outb(0, offset + MLXCPLD_HOTPLUG_MASK_OFF);
+	/* Read status. */
+	val = inb(offset) & mask;
+	asserted = *cache ^ val;
+	*cache = val;
+
+	/*
+	 * 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(dev, "False signal is received: register at offset 0x%02x, mask 0x%02x.\n",
+			offset, mask);
+		return;
+	}
+
+	for_each_set_bit(bit, (unsigned long *)&asserted, 8) {
+		if (val & BIT(bit)) {
+			if (is_inverse)
+				mlxcpld_hotplug_device_destroy(item + bit);
+			else
+				mlxcpld_hotplug_device_create(dev, item + bit);
+		} else {
+			if (is_inverse)
+				mlxcpld_hotplug_device_create(dev, item + bit);
+			else
+				mlxcpld_hotplug_device_destroy(item + bit);
+		}
+	}
+
+	/* Acknowledge event. */
+	outb(0, offset + MLXCPLD_HOTPLUG_EVENT_OFF);
+	/* Unmask event. */
+	outb(mask, offset + MLXCPLD_HOTPLUG_MASK_OFF);
+}
+
+/*
+ * mlxcpld_hotplug_work_handler - performs traversing of CPLD interrupt
+ * registers according to the below hierarchy schema:
+ *
+ *                   Aggregation registers (status/mask)
+ * PSU registers:           *---*
+ * *-----------------*      |   |
+ * |status/event/mask|----->| * |
+ * *-----------------*      |   |
+ * Power registers:         |   |
+ * *-----------------*      |   |
+ * |status/event/mask|----->| * |---> CPU
+ * *-----------------*      |   |
+ * FAN registers:
+ * *-----------------*      |   |
+ * |status/event/mask|----->| * |
+ * *-----------------*      |   |
+ *                          *---*
+ * In case some system changed are detected: FAN in/out, PSU in/out, power
+ * cable attached/detached, relevant device is created or destroyed.
+ */
+static void mlxcpld_hotplug_work_handler(struct work_struct *work)
+{
+	struct mlxcpld_hotplug_priv_data *priv = container_of(work,
+				struct mlxcpld_hotplug_priv_data, dwork.work);
+	u8 val, aggr_asserted;
+	unsigned long flags;
+
+	/* Mask aggregation event. */
+	outb(0, priv->plat->top_aggr_offset + MLXCPLD_HOTPLUG_AGGR_MASK_OFF);
+	/* Read aggregation status. */
+	val = inb(priv->plat->top_aggr_offset) & priv->plat->top_aggr_mask;
+	aggr_asserted = priv->aggr_cache ^ val;
+	priv->aggr_cache = val;
+
+	/* Handle PSU configuration changes. */
+	if (aggr_asserted & priv->plat->top_aggr_psu_mask)
+		mlxcpld_hotplug_work_helper(&priv->pdev->dev, priv->plat->psu,
+					    1, priv->plat->psu_reg_offset,
+					    priv->plat->psu_mask,
+					    &priv->psu_cache);
+
+	/* Handle power cable configuration changes. */
+	if (aggr_asserted & priv->plat->top_aggr_pwr_mask)
+		mlxcpld_hotplug_work_helper(&priv->pdev->dev, priv->plat->pwr,
+					    0, priv->plat->pwr_reg_offset,
+					    priv->plat->pwr_mask,
+					    &priv->pwr_cache);
+
+	/* Handle FAN configuration changes. */
+	if (aggr_asserted & priv->plat->top_aggr_fan_mask)
+		mlxcpld_hotplug_work_helper(&priv->pdev->dev, priv->plat->fan,
+					    1, priv->plat->fan_reg_offset,
+					    priv->plat->fan_mask,
+					    &priv->fan_cache);
+
+	if (aggr_asserted) {
+		spin_lock_irqsave(&priv->lock, flags);
+
+		/*
+		 * It is possible, that some signals have been inserted, while
+		 * interrupt has been masked by mlxcpld_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);
+		schedule_delayed_work(&priv->dwork, 0);
+
+		spin_unlock_irqrestore(&priv->lock, flags);
+
+		return;
+	}
+
+	/* Unmask aggregation event (no need acknowledge). */
+	outb(priv->plat->top_aggr_mask, priv->plat->top_aggr_offset +
+						MLXCPLD_HOTPLUG_AGGR_MASK_OFF);
+}
+
+static void mlxcpld_hotplug_set_irq(struct mlxcpld_hotplug_priv_data *priv)
+{
+	/* Clear psu presense event. */
+	outb(0, priv->plat->psu_reg_offset + MLXCPLD_HOTPLUG_EVENT_OFF);
+	/* Set psu initial status as mask and unmask psu event. */
+	priv->psu_cache = priv->plat->psu_mask;
+	outb(priv->plat->psu_mask, priv->plat->psu_reg_offset +
+						MLXCPLD_HOTPLUG_MASK_OFF);
+
+	/* Clear power cable event. */
+	outb(0, priv->plat->pwr_reg_offset + MLXCPLD_HOTPLUG_EVENT_OFF);
+	/* Keep power initial status as zero and unmask power event. */
+	outb(priv->plat->pwr_mask, priv->plat->pwr_reg_offset +
+						MLXCPLD_HOTPLUG_MASK_OFF);
+
+	/* Clear fan presense event. */
+	outb(0, priv->plat->fan_reg_offset + MLXCPLD_HOTPLUG_EVENT_OFF);
+	/* Set fan initial status as mask and unmask fan event. */
+	priv->fan_cache = priv->plat->fan_mask;
+	outb(priv->plat->fan_mask, priv->plat->fan_reg_offset +
+						MLXCPLD_HOTPLUG_MASK_OFF);
+
+	/* Keep aggregation initial status as zero and unmask events. */
+	outb(priv->plat->top_aggr_mask, priv->plat->top_aggr_offset +
+						MLXCPLD_HOTPLUG_AGGR_MASK_OFF);
+
+	/* Invoke work handler for initializing hot plug devices setting. */
+	mlxcpld_hotplug_work_handler(&priv->dwork.work);
+
+	enable_irq(priv->irq);
+}
+
+static void mlxcpld_hotplug_unset_irq(struct mlxcpld_hotplug_priv_data *priv)
+{
+	int i;
+
+	disable_irq(priv->irq);
+	cancel_delayed_work_sync(&priv->dwork);
+
+	/* Mask aggregation event. */
+	outb(0, priv->plat->top_aggr_offset + MLXCPLD_HOTPLUG_AGGR_MASK_OFF);
+
+	/* Mask psu presense event. */
+	outb(0, priv->plat->psu_reg_offset + MLXCPLD_HOTPLUG_MASK_OFF);
+	/* Clear psu presense event. */
+	outb(0, priv->plat->psu_reg_offset + MLXCPLD_HOTPLUG_EVENT_OFF);
+
+	/* Mask power cable event. */
+	outb(0, priv->plat->pwr_reg_offset + MLXCPLD_HOTPLUG_MASK_OFF);
+	/* Clear power cable event. */
+	outb(0, priv->plat->pwr_reg_offset + MLXCPLD_HOTPLUG_EVENT_OFF);
+
+	/* Mask fan presense event. */
+	outb(0, priv->plat->fan_reg_offset + MLXCPLD_HOTPLUG_MASK_OFF);
+	/* Clear fan presense event. */
+	outb(0, priv->plat->fan_reg_offset + MLXCPLD_HOTPLUG_EVENT_OFF);
+
+	/* Remove all the attached devices. */
+	for (i = 0; i < priv->plat->psu_count; i++)
+		mlxcpld_hotplug_device_destroy(priv->plat->psu + i);
+
+	for (i = 0; i < priv->plat->pwr_count; i++)
+		mlxcpld_hotplug_device_destroy(priv->plat->pwr + i);
+
+	for (i = 0; i < priv->plat->fan_count; i++)
+		mlxcpld_hotplug_device_destroy(priv->plat->fan + i);
+}
+
+static irqreturn_t mlxcpld_hotplug_irq_handler(int irq, void *dev)
+{
+	struct mlxcpld_hotplug_priv_data *priv =
+				(struct mlxcpld_hotplug_priv_data *)dev;
+
+	/* Schedule work task for immediate execution.*/
+	schedule_delayed_work(&priv->dwork, 0);
+
+	return IRQ_HANDLED;
+}
+
+static int mlxcpld_hotplug_probe(struct platform_device *pdev)
+{
+	struct mlxcpld_hotplug_platform_data *pdata;
+	struct mlxcpld_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;
+
+	priv->pdev = pdev;
+	priv->plat = pdata;
+
+	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;
+	}
+
+	err = devm_request_irq(&pdev->dev, priv->irq,
+				mlxcpld_hotplug_irq_handler, 0, pdev->name,
+				priv);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to request irq: %d\n", err);
+		return err;
+	}
+	disable_irq(priv->irq);
+
+	INIT_DELAYED_WORK(&priv->dwork, mlxcpld_hotplug_work_handler);
+	spin_lock_init(&priv->lock);
+
+	err = mlxcpld_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,
+					"mlxcpld_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);
+	}
+
+	platform_set_drvdata(pdev, priv);
+
+	/* Perform initial interrupts setup. */
+	mlxcpld_hotplug_set_irq(priv);
+
+	return 0;
+}
+
+static int mlxcpld_hotplug_remove(struct platform_device *pdev)
+{
+	struct mlxcpld_hotplug_priv_data *priv = platform_get_drvdata(pdev);
+
+	/* Clean interrupts setup. */
+	mlxcpld_hotplug_unset_irq(priv);
+
+	return 0;
+}
+
+static struct platform_driver mlxcpld_hotplug_driver = {
+	.driver = {
+		.name = "mlxcpld-hotplug",
+	},
+	.probe = mlxcpld_hotplug_probe,
+	.remove = mlxcpld_hotplug_remove,
+};
+
+module_platform_driver(mlxcpld_hotplug_driver);
+
+MODULE_AUTHOR("Vadim Pasternak <vadimp@...lanox.com>");
+MODULE_DESCRIPTION("Mellanox CPLD hotplug platform driver");
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_ALIAS("platform:mlxcpld-hotplug");
diff --git a/include/linux/platform_data/mlxcpld-hotplug.h b/include/linux/platform_data/mlxcpld-hotplug.h
new file mode 100644
index 0000000..e4cfcff
--- /dev/null
+++ b/include/linux/platform_data/mlxcpld-hotplug.h
@@ -0,0 +1,99 @@
+/*
+ * include/linux/platform_data/mlxcpld-hotplug.h
+ * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2016 Vadim Pasternak <vadimp@...lanox.com>
+ *
+ * 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_MLXCPLD_HOTPLUG_H
+#define __LINUX_PLATFORM_DATA_MLXCPLD_HOTPLUG_H
+
+/**
+ * struct mlxcpld_hotplug_device - I2C device data:
+ * @adapter: I2C device adapter;
+ * @client: I2C device client;
+ * @brdinfo: device board information;
+ * @bus: I2C bus, where device is attached;
+ *
+ * Structure represents I2C hotplug device static data (board topology) and
+ * dynamic data (related kernel objects handles).
+ */
+struct mlxcpld_hotplug_device {
+	struct i2c_adapter *adapter;
+	struct i2c_client *client;
+	struct i2c_board_info brdinfo;
+	u16 bus;
+};
+
+/**
+ * struct mlxcpld_hotplug_platform_data - device platform data:
+ * @top_aggr_offset: offset of top aggregation interrupt register;
+ * @top_aggr_mask: top aggregation interrupt common mask;
+ * @top_aggr_psu_mask: top aggregation interrupt PSU mask;
+ * @psu_reg_offset: offset of PSU interrupt register;
+ * @psu_mask: PSU interrupt mask;
+ * @psu_count: number of equipped replaceable PSUs;
+ * @psu: pointer to PSU devices data array;
+ * @top_aggr_pwr_mask: top aggregation interrupt power mask;
+ * @pwr_reg_offset: offset of power interrupt register
+ * @pwr_mask: power interrupt mask;
+ * @pwr_count: number of power sources;
+ * @pwr: pointer to power devices data array;
+ * @top_aggr_fan_mask: top aggregation interrupt FAN mask;
+ * @fan_reg_offset: offset of FAN interrupt register;
+ * @fan_mask: FAN interrupt mask;
+ * @fan_count: number of equipped replaceable FANs;
+ * @fan: pointer to FAN devices data array;
+ *
+ * Structure represents board platform data, related to system hotplug events,
+ * like FAN, PSU, power cable insertion and removing. This data provides the
+ * number of hot-pluggable devices and hardware description for event handling.
+ */
+struct mlxcpld_hotplug_platform_data {
+	u16 top_aggr_offset;
+	u8 top_aggr_mask;
+	u8 top_aggr_psu_mask;
+	u16 psu_reg_offset;
+	u8 psu_mask;
+	u8 psu_count;
+	struct mlxcpld_hotplug_device *psu;
+	u8 top_aggr_pwr_mask;
+	u16 pwr_reg_offset;
+	u8 pwr_mask;
+	u8 pwr_count;
+	struct mlxcpld_hotplug_device *pwr;
+	u8 top_aggr_fan_mask;
+	u16 fan_reg_offset;
+	u8 fan_mask;
+	u8 fan_count;
+	struct mlxcpld_hotplug_device *fan;
+};
+
+#endif /* __LINUX_PLATFORM_DATA_MLXCPLD_HOTPLUG_H */
-- 
2.1.4

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