drivers/misc/mei/wd.c - maze/linux - Git at Google

 /*
  *
  * Intel Management Engine Interface (Intel MEI) Linux driver
  * Copyright (c) 2003-2012, Intel Corporation.
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
  * version 2, as published by the Free Software Foundation.
  *
  * This program is distributed in the hope it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  * more details.
  *
  */
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/device.h>
 #include <linux/pci.h>
 #include <linux/sched.h>
 #include <linux/watchdog.h>

 #include "mei_dev.h"
 #include "hw.h"
 #include "interface.h"
 #include <linux/mei.h>

 static const u8 mei_start_wd_params[] = { 0x02, 0x12, 0x13, 0x10 };
 static const u8 mei_stop_wd_params[] = { 0x02, 0x02, 0x14, 0x10 };

 const u8 mei_wd_state_independence_msg[3][4] = {
 	{0x05, 0x02, 0x51, 0x10},
 	{0x05, 0x02, 0x52, 0x10},
 	{0x07, 0x02, 0x01, 0x10}
 };

 /*
  * AMT Watchdog Device
  */
 #define INTEL_AMT_WATCHDOG_ID "INTCAMT"

 /* UUIDs for AMT F/W clients */
 const uuid_le mei_wd_guid = UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, 0x89,
 						0x9D, 0xA9, 0x15, 0x14, 0xCB,
 						0x32, 0xAB);

 static void mei_wd_set_start_timeout(struct mei_device *dev, u16 timeout)
 {
 	dev_dbg(&dev->pdev->dev, "wd: set timeout=%d.\n", timeout);
 	memcpy(dev->wd_data, mei_start_wd_params, MEI_WD_PARAMS_SIZE);
 	memcpy(dev->wd_data + MEI_WD_PARAMS_SIZE, &timeout, sizeof(u16));
 }

 /**
  * host_init_wd - mei initialization wd.
  *
  * @dev: the device structure
  * returns -ENENT if wd client cannot be found
  *         -EIO if write has failed
  */
 int mei_wd_host_init(struct mei_device *dev)
 {
 	mei_cl_init(&dev->wd_cl, dev);

 	/* look for WD client and connect to it */
 	dev->wd_cl.state = MEI_FILE_DISCONNECTED;
 	dev->wd_timeout = AMT_WD_DEFAULT_TIMEOUT;

 	/* find ME WD client */
 	mei_find_me_client_update_filext(dev, &dev->wd_cl,
 				&mei_wd_guid, MEI_WD_HOST_CLIENT_ID);

 	dev_dbg(&dev->pdev->dev, "wd: check client\n");
 	if (MEI_FILE_CONNECTING != dev->wd_cl.state) {
 		dev_info(&dev->pdev->dev, "wd: failed to find the client\n");
 		return -ENOENT;
 	}

 	if (mei_connect(dev, &dev->wd_cl)) {
 		dev_err(&dev->pdev->dev, "wd: failed to connect to the client\n");
 		dev->wd_cl.state = MEI_FILE_DISCONNECTED;
 		dev->wd_cl.host_client_id = 0;
 		return -EIO;
 	}
 	dev->wd_cl.timer_count = CONNECT_TIMEOUT;

 	return 0;
 }

 /**
  * mei_wd_send - sends watch dog message to fw.
  *
  * @dev: the device structure
  *
  * returns 0 if success,
  *	-EIO when message send fails
  *	-EINVAL when invalid message is to be sent
  */
 int mei_wd_send(struct mei_device *dev)
 {
 	struct mei_msg_hdr *mei_hdr;

 	mei_hdr = (struct mei_msg_hdr *) &dev->wr_msg_buf[0];
 	mei_hdr->host_addr = dev->wd_cl.host_client_id;
 	mei_hdr->me_addr = dev->wd_cl.me_client_id;
 	mei_hdr->msg_complete = 1;
 	mei_hdr->reserved = 0;

 	if (!memcmp(dev->wd_data, mei_start_wd_params, MEI_WD_PARAMS_SIZE))
 		mei_hdr->length = MEI_START_WD_DATA_SIZE;
 	else if (!memcmp(dev->wd_data, mei_stop_wd_params, MEI_WD_PARAMS_SIZE))
 		mei_hdr->length = MEI_WD_PARAMS_SIZE;
 	else
 		return -EINVAL;

 	return mei_write_message(dev, mei_hdr, dev->wd_data, mei_hdr->length);
 }

 /**
  * mei_wd_stop - sends watchdog stop message to fw.
  *
  * @dev: the device structure
  * @preserve: indicate if to keep the timeout value
  *
  * returns 0 if success,
  *	-EIO when message send fails
  *	-EINVAL when invalid message is to be sent
  */
 int mei_wd_stop(struct mei_device *dev, bool preserve)
 {
 	int ret;
 	u16 wd_timeout = dev->wd_timeout;

 	cancel_delayed_work(&dev->timer_work);
 	if (dev->wd_cl.state != MEI_FILE_CONNECTED || !dev->wd_timeout)
 		return 0;

 	dev->wd_timeout = 0;
 	dev->wd_due_counter = 0;
 	memcpy(dev->wd_data, mei_stop_wd_params, MEI_WD_PARAMS_SIZE);
 	dev->stop = true;

 	ret = mei_flow_ctrl_creds(dev, &dev->wd_cl);
 	if (ret < 0)
 		goto out;

 	if (ret && dev->mei_host_buffer_is_empty) {
 		ret = 0;
 		dev->mei_host_buffer_is_empty = false;

 		if (!mei_wd_send(dev)) {
 			ret = mei_flow_ctrl_reduce(dev, &dev->wd_cl);
 			if (ret)
 				goto out;
 		} else {
 			dev_err(&dev->pdev->dev, "wd: send stop failed\n");
 		}

 		dev->wd_pending = false;
 	} else {
 		dev->wd_pending = true;
 	}
 	dev->wd_stopped = false;
 	mutex_unlock(&dev->device_lock);

 	ret = wait_event_interruptible_timeout(dev->wait_stop_wd,
 					dev->wd_stopped, 10 * HZ);
 	mutex_lock(&dev->device_lock);
 	if (dev->wd_stopped) {
 		dev_dbg(&dev->pdev->dev, "wd: stop completed ret=%d.\n", ret);
 		ret = 0;
 	} else {
 		if (!ret)
 			ret = -ETIMEDOUT;
 		dev_warn(&dev->pdev->dev,
 			"wd: stop failed to complete ret=%d.\n", ret);
 	}

 	if (preserve)
 		dev->wd_timeout = wd_timeout;

 out:
 	return ret;
 }

 /*
  * mei_wd_ops_start - wd start command from the watchdog core.
  *
  * @wd_dev - watchdog device struct
  *
  * returns 0 if success, negative errno code for failure
  */
 static int mei_wd_ops_start(struct watchdog_device *wd_dev)
 {
 	int err = -ENODEV;
 	struct mei_device *dev;

 	dev = pci_get_drvdata(mei_device);
 	if (!dev)
 		return -ENODEV;

 	mutex_lock(&dev->device_lock);

 	if (dev->mei_state != MEI_ENABLED) {
 		dev_dbg(&dev->pdev->dev,
 			"wd: mei_state != MEI_ENABLED  mei_state = %d\n",
 			dev->mei_state);
 		goto end_unlock;
 	}

 	if (dev->wd_cl.state != MEI_FILE_CONNECTED)	{
 		dev_dbg(&dev->pdev->dev,
 			"MEI Driver is not connected to Watchdog Client\n");
 		goto end_unlock;
 	}

 	mei_wd_set_start_timeout(dev, dev->wd_timeout);

 	err = 0;
 end_unlock:
 	mutex_unlock(&dev->device_lock);
 	return err;
 }

 /*
  * mei_wd_ops_stop -  wd stop command from the watchdog core.
  *
  * @wd_dev - watchdog device struct
  *
  * returns 0 if success, negative errno code for failure
  */
 static int mei_wd_ops_stop(struct watchdog_device *wd_dev)
 {
 	struct mei_device *dev;
 	dev = pci_get_drvdata(mei_device);

 	if (!dev)
 		return -ENODEV;

 	mutex_lock(&dev->device_lock);
 	mei_wd_stop(dev, false);
 	mutex_unlock(&dev->device_lock);

 	return 0;
 }

 /*
  * mei_wd_ops_ping - wd ping command from the watchdog core.
  *
  * @wd_dev - watchdog device struct
  *
  * returns 0 if success, negative errno code for failure
  */
 static int mei_wd_ops_ping(struct watchdog_device *wd_dev)
 {
 	int ret = 0;
 	struct mei_device *dev;
 	dev = pci_get_drvdata(mei_device);

 	if (!dev)
 		return -ENODEV;

 	mutex_lock(&dev->device_lock);

 	if (dev->wd_cl.state != MEI_FILE_CONNECTED) {
 		dev_err(&dev->pdev->dev, "wd: not connected.\n");
 		ret = -ENODEV;
 		goto end;
 	}

 	/* Check if we can send the ping to HW*/
 	if (dev->mei_host_buffer_is_empty &&
 		mei_flow_ctrl_creds(dev, &dev->wd_cl) > 0) {

 		dev->mei_host_buffer_is_empty = false;
 		dev_dbg(&dev->pdev->dev, "wd: sending ping\n");

 		if (mei_wd_send(dev)) {
 			dev_err(&dev->pdev->dev, "wd: send failed.\n");
 			ret = -EIO;
 			goto end;
 		}

 		if (mei_flow_ctrl_reduce(dev, &dev->wd_cl)) {
 			dev_err(&dev->pdev->dev,
 				"wd: mei_flow_ctrl_reduce() failed.\n");
 			ret = -EIO;
 			goto end;
 		}

 	} else {
 		dev->wd_pending = true;
 	}

 end:
 	mutex_unlock(&dev->device_lock);
 	return ret;
 }

 /*
  * mei_wd_ops_set_timeout - wd set timeout command from the watchdog core.
  *
  * @wd_dev - watchdog device struct
  * @timeout - timeout value to set
  *
  * returns 0 if success, negative errno code for failure
  */
 static int mei_wd_ops_set_timeout(struct watchdog_device *wd_dev, unsigned int timeout)
 {
 	struct mei_device *dev;
 	dev = pci_get_drvdata(mei_device);

 	if (!dev)
 		return -ENODEV;

 	/* Check Timeout value */
 	if (timeout < AMT_WD_MIN_TIMEOUT || timeout > AMT_WD_MAX_TIMEOUT)
 		return -EINVAL;

 	mutex_lock(&dev->device_lock);

 	dev->wd_timeout = timeout;
 	wd_dev->timeout = timeout;
 	mei_wd_set_start_timeout(dev, dev->wd_timeout);

 	mutex_unlock(&dev->device_lock);

 	return 0;
 }

 /*
  * Watchdog Device structs
  */
 static const struct watchdog_ops wd_ops = {
 		.owner = THIS_MODULE,
 		.start = mei_wd_ops_start,
 		.stop = mei_wd_ops_stop,
 		.ping = mei_wd_ops_ping,
 		.set_timeout = mei_wd_ops_set_timeout,
 };
 static const struct watchdog_info wd_info = {
 		.identity = INTEL_AMT_WATCHDOG_ID,
 		.options = WDIOF_KEEPALIVEPING,
 };

 static struct watchdog_device amt_wd_dev = {
 		.info = &wd_info,
 		.ops = &wd_ops,
 		.timeout = AMT_WD_DEFAULT_TIMEOUT,
 		.min_timeout = AMT_WD_MIN_TIMEOUT,
 		.max_timeout = AMT_WD_MAX_TIMEOUT,
 };


 void  mei_watchdog_register(struct mei_device *dev)
 {
 	dev_dbg(&dev->pdev->dev, "dev->wd_timeout =%d.\n", dev->wd_timeout);

 	dev->wd_due_counter = !!dev->wd_timeout;

 	if (watchdog_register_device(&amt_wd_dev)) {
 		dev_err(&dev->pdev->dev,
 			"wd: unable to register watchdog device.\n");
 		dev->wd_interface_reg = false;
 	} else {
 		dev_dbg(&dev->pdev->dev,
 			"wd: successfully register watchdog interface.\n");
 		dev->wd_interface_reg = true;
 	}
 }

 void mei_watchdog_unregister(struct mei_device *dev)
 {
 	if (dev->wd_interface_reg)
 		watchdog_unregister_device(&amt_wd_dev);
 	dev->wd_interface_reg = false;
 }
	/*
	*
	* Intel Management Engine Interface (Intel MEI) Linux driver
	* Copyright (c) 2003-2012, Intel Corporation.
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms and conditions of the GNU General Public License,
	* version 2, as published by the Free Software Foundation.
	*
	* This program is distributed in the hope it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	* more details.
	*
	*/
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/device.h>
	#include <linux/pci.h>
	#include <linux/sched.h>
	#include <linux/watchdog.h>

	#include "mei_dev.h"
	#include "hw.h"
	#include "interface.h"
	#include <linux/mei.h>

	static const u8 mei_start_wd_params[] = { 0x02, 0x12, 0x13, 0x10 };
	static const u8 mei_stop_wd_params[] = { 0x02, 0x02, 0x14, 0x10 };

	const u8 mei_wd_state_independence_msg[3][4] = {
	{0x05, 0x02, 0x51, 0x10},
	{0x05, 0x02, 0x52, 0x10},
	{0x07, 0x02, 0x01, 0x10}
	};

	/*
	* AMT Watchdog Device
	*/
	#define INTEL_AMT_WATCHDOG_ID "INTCAMT"

	/* UUIDs for AMT F/W clients */
	const uuid_le mei_wd_guid = UUID_LE(0x05B79A6F, 0x4628, 0x4D7F, 0x89,
	0x9D, 0xA9, 0x15, 0x14, 0xCB,
	0x32, 0xAB);

	static void mei_wd_set_start_timeout(struct mei_device *dev, u16 timeout)
	{
	dev_dbg(&dev->pdev->dev, "wd: set timeout=%d.\n", timeout);
	memcpy(dev->wd_data, mei_start_wd_params, MEI_WD_PARAMS_SIZE);
	memcpy(dev->wd_data + MEI_WD_PARAMS_SIZE, &timeout, sizeof(u16));
	}

	/**
	* host_init_wd - mei initialization wd.
	*
	* @dev: the device structure
	* returns -ENENT if wd client cannot be found
	* -EIO if write has failed
	*/
	int mei_wd_host_init(struct mei_device *dev)
	{
	mei_cl_init(&dev->wd_cl, dev);

	/* look for WD client and connect to it */
	dev->wd_cl.state = MEI_FILE_DISCONNECTED;
	dev->wd_timeout = AMT_WD_DEFAULT_TIMEOUT;

	/* find ME WD client */
	mei_find_me_client_update_filext(dev, &dev->wd_cl,
	&mei_wd_guid, MEI_WD_HOST_CLIENT_ID);

	dev_dbg(&dev->pdev->dev, "wd: check client\n");
	if (MEI_FILE_CONNECTING != dev->wd_cl.state) {
	dev_info(&dev->pdev->dev, "wd: failed to find the client\n");
	return -ENOENT;
	}

	if (mei_connect(dev, &dev->wd_cl)) {
	dev_err(&dev->pdev->dev, "wd: failed to connect to the client\n");
	dev->wd_cl.state = MEI_FILE_DISCONNECTED;
	dev->wd_cl.host_client_id = 0;
	return -EIO;
	}
	dev->wd_cl.timer_count = CONNECT_TIMEOUT;

	return 0;
	}

	/**
	* mei_wd_send - sends watch dog message to fw.
	*
	* @dev: the device structure
	*
	* returns 0 if success,
	* -EIO when message send fails
	* -EINVAL when invalid message is to be sent
	*/
	int mei_wd_send(struct mei_device *dev)
	{
	struct mei_msg_hdr *mei_hdr;

	mei_hdr = (struct mei_msg_hdr *) &dev->wr_msg_buf[0];
	mei_hdr->host_addr = dev->wd_cl.host_client_id;
	mei_hdr->me_addr = dev->wd_cl.me_client_id;
	mei_hdr->msg_complete = 1;
	mei_hdr->reserved = 0;

	if (!memcmp(dev->wd_data, mei_start_wd_params, MEI_WD_PARAMS_SIZE))
	mei_hdr->length = MEI_START_WD_DATA_SIZE;
	else if (!memcmp(dev->wd_data, mei_stop_wd_params, MEI_WD_PARAMS_SIZE))
	mei_hdr->length = MEI_WD_PARAMS_SIZE;
	else
	return -EINVAL;

	return mei_write_message(dev, mei_hdr, dev->wd_data, mei_hdr->length);
	}

	/**
	* mei_wd_stop - sends watchdog stop message to fw.
	*
	* @dev: the device structure
	* @preserve: indicate if to keep the timeout value
	*
	* returns 0 if success,
	* -EIO when message send fails
	* -EINVAL when invalid message is to be sent
	*/
	int mei_wd_stop(struct mei_device *dev, bool preserve)
	{
	int ret;
	u16 wd_timeout = dev->wd_timeout;

	cancel_delayed_work(&dev->timer_work);
	if (dev->wd_cl.state != MEI_FILE_CONNECTED \|\| !dev->wd_timeout)
	return 0;

	dev->wd_timeout = 0;
	dev->wd_due_counter = 0;
	memcpy(dev->wd_data, mei_stop_wd_params, MEI_WD_PARAMS_SIZE);
	dev->stop = true;

	ret = mei_flow_ctrl_creds(dev, &dev->wd_cl);
	if (ret < 0)
	goto out;

	if (ret && dev->mei_host_buffer_is_empty) {
	ret = 0;
	dev->mei_host_buffer_is_empty = false;

	if (!mei_wd_send(dev)) {
	ret = mei_flow_ctrl_reduce(dev, &dev->wd_cl);
	if (ret)
	goto out;
	} else {
	dev_err(&dev->pdev->dev, "wd: send stop failed\n");
	}

	dev->wd_pending = false;
	} else {
	dev->wd_pending = true;
	}
	dev->wd_stopped = false;
	mutex_unlock(&dev->device_lock);

	ret = wait_event_interruptible_timeout(dev->wait_stop_wd,
	dev->wd_stopped, 10 * HZ);
	mutex_lock(&dev->device_lock);
	if (dev->wd_stopped) {
	dev_dbg(&dev->pdev->dev, "wd: stop completed ret=%d.\n", ret);
	ret = 0;
	} else {
	if (!ret)
	ret = -ETIMEDOUT;
	dev_warn(&dev->pdev->dev,
	"wd: stop failed to complete ret=%d.\n", ret);
	}

	if (preserve)
	dev->wd_timeout = wd_timeout;

	out:
	return ret;
	}

	/*
	* mei_wd_ops_start - wd start command from the watchdog core.
	*
	* @wd_dev - watchdog device struct
	*
	* returns 0 if success, negative errno code for failure
	*/
	static int mei_wd_ops_start(struct watchdog_device *wd_dev)
	{
	int err = -ENODEV;
	struct mei_device *dev;

	dev = pci_get_drvdata(mei_device);
	if (!dev)
	return -ENODEV;

	mutex_lock(&dev->device_lock);

	if (dev->mei_state != MEI_ENABLED) {
	dev_dbg(&dev->pdev->dev,
	"wd: mei_state != MEI_ENABLED mei_state = %d\n",
	dev->mei_state);
	goto end_unlock;
	}

	if (dev->wd_cl.state != MEI_FILE_CONNECTED) {
	dev_dbg(&dev->pdev->dev,
	"MEI Driver is not connected to Watchdog Client\n");
	goto end_unlock;
	}

	mei_wd_set_start_timeout(dev, dev->wd_timeout);

	err = 0;
	end_unlock:
	mutex_unlock(&dev->device_lock);
	return err;
	}

	/*
	* mei_wd_ops_stop - wd stop command from the watchdog core.
	*
	* @wd_dev - watchdog device struct
	*
	* returns 0 if success, negative errno code for failure
	*/
	static int mei_wd_ops_stop(struct watchdog_device *wd_dev)
	{
	struct mei_device *dev;
	dev = pci_get_drvdata(mei_device);

	if (!dev)
	return -ENODEV;

	mutex_lock(&dev->device_lock);
	mei_wd_stop(dev, false);
	mutex_unlock(&dev->device_lock);

	return 0;
	}

	/*
	* mei_wd_ops_ping - wd ping command from the watchdog core.
	*
	* @wd_dev - watchdog device struct
	*
	* returns 0 if success, negative errno code for failure
	*/
	static int mei_wd_ops_ping(struct watchdog_device *wd_dev)
	{
	int ret = 0;
	struct mei_device *dev;
	dev = pci_get_drvdata(mei_device);

	if (!dev)
	return -ENODEV;

	mutex_lock(&dev->device_lock);

	if (dev->wd_cl.state != MEI_FILE_CONNECTED) {
	dev_err(&dev->pdev->dev, "wd: not connected.\n");
	ret = -ENODEV;
	goto end;
	}

	/* Check if we can send the ping to HW*/
	if (dev->mei_host_buffer_is_empty &&
	mei_flow_ctrl_creds(dev, &dev->wd_cl) > 0) {

	dev->mei_host_buffer_is_empty = false;
	dev_dbg(&dev->pdev->dev, "wd: sending ping\n");

	if (mei_wd_send(dev)) {
	dev_err(&dev->pdev->dev, "wd: send failed.\n");
	ret = -EIO;
	goto end;
	}

	if (mei_flow_ctrl_reduce(dev, &dev->wd_cl)) {
	dev_err(&dev->pdev->dev,
	"wd: mei_flow_ctrl_reduce() failed.\n");
	ret = -EIO;
	goto end;
	}

	} else {
	dev->wd_pending = true;
	}

	end:
	mutex_unlock(&dev->device_lock);
	return ret;
	}

	/*
	* mei_wd_ops_set_timeout - wd set timeout command from the watchdog core.
	*
	* @wd_dev - watchdog device struct
	* @timeout - timeout value to set
	*
	* returns 0 if success, negative errno code for failure
	*/
	static int mei_wd_ops_set_timeout(struct watchdog_device *wd_dev, unsigned int timeout)
	{
	struct mei_device *dev;
	dev = pci_get_drvdata(mei_device);

	if (!dev)
	return -ENODEV;

	/* Check Timeout value */
	if (timeout < AMT_WD_MIN_TIMEOUT \|\| timeout > AMT_WD_MAX_TIMEOUT)
	return -EINVAL;

	mutex_lock(&dev->device_lock);

	dev->wd_timeout = timeout;
	wd_dev->timeout = timeout;
	mei_wd_set_start_timeout(dev, dev->wd_timeout);

	mutex_unlock(&dev->device_lock);

	return 0;
	}

	/*
	* Watchdog Device structs
	*/
	static const struct watchdog_ops wd_ops = {
	.owner = THIS_MODULE,
	.start = mei_wd_ops_start,
	.stop = mei_wd_ops_stop,
	.ping = mei_wd_ops_ping,
	.set_timeout = mei_wd_ops_set_timeout,
	};
	static const struct watchdog_info wd_info = {
	.identity = INTEL_AMT_WATCHDOG_ID,
	.options = WDIOF_KEEPALIVEPING,
	};

	static struct watchdog_device amt_wd_dev = {
	.info = &wd_info,
	.ops = &wd_ops,
	.timeout = AMT_WD_DEFAULT_TIMEOUT,
	.min_timeout = AMT_WD_MIN_TIMEOUT,
	.max_timeout = AMT_WD_MAX_TIMEOUT,
	};


	void mei_watchdog_register(struct mei_device *dev)
	{
	dev_dbg(&dev->pdev->dev, "dev->wd_timeout =%d.\n", dev->wd_timeout);

	dev->wd_due_counter = !!dev->wd_timeout;

	if (watchdog_register_device(&amt_wd_dev)) {
	dev_err(&dev->pdev->dev,
	"wd: unable to register watchdog device.\n");
	dev->wd_interface_reg = false;
	} else {
	dev_dbg(&dev->pdev->dev,
	"wd: successfully register watchdog interface.\n");
	dev->wd_interface_reg = true;
	}
	}

	void mei_watchdog_unregister(struct mei_device *dev)
	{
	if (dev->wd_interface_reg)
	watchdog_unregister_device(&amt_wd_dev);
	dev->wd_interface_reg = false;
	}