Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1322 insertions, 0 deletions

diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
new file mode 100644
index 000000000..9f6682033
--- /dev/null
+++ b/drivers/misc/mei/main.c
@@ -0,0 +1,1322 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2003-2020, Intel Corporation. All rights reserved.
+ * Intel Management Engine Interface (Intel MEI) Linux driver
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/fcntl.h>
+#include <linux/poll.h>
+#include <linux/init.h>
+#include <linux/ioctl.h>
+#include <linux/cdev.h>
+#include <linux/sched/signal.h>
+#include <linux/uuid.h>
+#include <linux/compat.h>
+#include <linux/jiffies.h>
+#include <linux/interrupt.h>
+
+#include <linux/mei.h>
+
+#include "mei_dev.h"
+#include "client.h"
+
+static struct class *mei_class;
+static dev_t mei_devt;
+#define MEI_MAX_DEVS  MINORMASK
+static DEFINE_MUTEX(mei_minor_lock);
+static DEFINE_IDR(mei_idr);
+
+/**
+ * mei_open - the open function
+ *
+ * @inode: pointer to inode structure
+ * @file: pointer to file structure
+ *
+ * Return: 0 on success, <0 on error
+ */
+static int mei_open(struct inode *inode, struct file *file)
+{
+	struct mei_device *dev;
+	struct mei_cl *cl;
+
+	int err;
+
+	dev = container_of(inode->i_cdev, struct mei_device, cdev);
+	if (!dev)
+		return -ENODEV;
+
+	mutex_lock(&dev->device_lock);
+
+	if (dev->dev_state != MEI_DEV_ENABLED) {
+		dev_dbg(dev->dev, "dev_state != MEI_ENABLED  dev_state = %s\n",
+		    mei_dev_state_str(dev->dev_state));
+		err = -ENODEV;
+		goto err_unlock;
+	}
+
+	cl = mei_cl_alloc_linked(dev);
+	if (IS_ERR(cl)) {
+		err = PTR_ERR(cl);
+		goto err_unlock;
+	}
+
+	cl->fp = file;
+	file->private_data = cl;
+
+	mutex_unlock(&dev->device_lock);
+
+	return nonseekable_open(inode, file);
+
+err_unlock:
+	mutex_unlock(&dev->device_lock);
+	return err;
+}
+
+/**
+ * mei_cl_vtag_remove_by_fp - remove vtag that corresponds to fp from list
+ *
+ * @cl: host client
+ * @fp: pointer to file structure
+ *
+ */
+static void mei_cl_vtag_remove_by_fp(const struct mei_cl *cl,
+				     const struct file *fp)
+{
+	struct mei_cl_vtag *vtag_l, *next;
+
+	list_for_each_entry_safe(vtag_l, next, &cl->vtag_map, list) {
+		if (vtag_l->fp == fp) {
+			list_del(&vtag_l->list);
+			kfree(vtag_l);
+			return;
+		}
+	}
+}
+
+/**
+ * mei_release - the release function
+ *
+ * @inode: pointer to inode structure
+ * @file: pointer to file structure
+ *
+ * Return: 0 on success, <0 on error
+ */
+static int mei_release(struct inode *inode, struct file *file)
+{
+	struct mei_cl *cl = file->private_data;
+	struct mei_device *dev;
+	int rets;
+
+	if (WARN_ON(!cl || !cl->dev))
+		return -ENODEV;
+
+	dev = cl->dev;
+
+	mutex_lock(&dev->device_lock);
+
+	mei_cl_vtag_remove_by_fp(cl, file);
+
+	if (!list_empty(&cl->vtag_map)) {
+		cl_dbg(dev, cl, "not the last vtag\n");
+		mei_cl_flush_queues(cl, file);
+		rets = 0;
+		goto out;
+	}
+
+	rets = mei_cl_disconnect(cl);
+	/*
+	 * Check again: This is necessary since disconnect releases the lock
+	 * and another client can connect in the meantime.
+	 */
+	if (!list_empty(&cl->vtag_map)) {
+		cl_dbg(dev, cl, "not the last vtag after disconnect\n");
+		mei_cl_flush_queues(cl, file);
+		goto out;
+	}
+
+	mei_cl_flush_queues(cl, NULL);
+	cl_dbg(dev, cl, "removing\n");
+
+	mei_cl_unlink(cl);
+	kfree(cl);
+
+out:
+	file->private_data = NULL;
+
+	mutex_unlock(&dev->device_lock);
+	return rets;
+}
+
+
+/**
+ * mei_read - the read function.
+ *
+ * @file: pointer to file structure
+ * @ubuf: pointer to user buffer
+ * @length: buffer length
+ * @offset: data offset in buffer
+ *
+ * Return: >=0 data length on success , <0 on error
+ */
+static ssize_t mei_read(struct file *file, char __user *ubuf,
+			size_t length, loff_t *offset)
+{
+	struct mei_cl *cl = file->private_data;
+	struct mei_device *dev;
+	struct mei_cl_cb *cb = NULL;
+	bool nonblock = !!(file->f_flags & O_NONBLOCK);
+	ssize_t rets;
+
+	if (WARN_ON(!cl || !cl->dev))
+		return -ENODEV;
+
+	dev = cl->dev;
+
+
+	mutex_lock(&dev->device_lock);
+	if (dev->dev_state != MEI_DEV_ENABLED) {
+		rets = -ENODEV;
+		goto out;
+	}
+
+	if (length == 0) {
+		rets = 0;
+		goto out;
+	}
+
+	if (ubuf == NULL) {
+		rets = -EMSGSIZE;
+		goto out;
+	}
+
+	cb = mei_cl_read_cb(cl, file);
+	if (cb)
+		goto copy_buffer;
+
+	if (*offset > 0)
+		*offset = 0;
+
+	rets = mei_cl_read_start(cl, length, file);
+	if (rets && rets != -EBUSY) {
+		cl_dbg(dev, cl, "mei start read failure status = %zd\n", rets);
+		goto out;
+	}
+
+	if (nonblock) {
+		rets = -EAGAIN;
+		goto out;
+	}
+
+	mutex_unlock(&dev->device_lock);
+	if (wait_event_interruptible(cl->rx_wait,
+				     mei_cl_read_cb(cl, file) ||
+				     !mei_cl_is_connected(cl))) {
+		if (signal_pending(current))
+			return -EINTR;
+		return -ERESTARTSYS;
+	}
+	mutex_lock(&dev->device_lock);
+
+	if (!mei_cl_is_connected(cl)) {
+		rets = -ENODEV;
+		goto out;
+	}
+
+	cb = mei_cl_read_cb(cl, file);
+	if (!cb) {
+		rets = 0;
+		goto out;
+	}
+
+copy_buffer:
+	/* now copy the data to user space */
+	if (cb->status) {
+		rets = cb->status;
+		cl_dbg(dev, cl, "read operation failed %zd\n", rets);
+		goto free;
+	}
+
+	cl_dbg(dev, cl, "buf.size = %zu buf.idx = %zu offset = %lld\n",
+	       cb->buf.size, cb->buf_idx, *offset);
+	if (*offset >= cb->buf_idx) {
+		rets = 0;
+		goto free;
+	}
+
+	/* length is being truncated to PAGE_SIZE,
+	 * however buf_idx may point beyond that */
+	length = min_t(size_t, length, cb->buf_idx - *offset);
+
+	if (copy_to_user(ubuf, cb->buf.data + *offset, length)) {
+		dev_dbg(dev->dev, "failed to copy data to userland\n");
+		rets = -EFAULT;
+		goto free;
+	}
+
+	rets = length;
+	*offset += length;
+	/* not all data was read, keep the cb */
+	if (*offset < cb->buf_idx)
+		goto out;
+
+free:
+	mei_cl_del_rd_completed(cl, cb);
+	*offset = 0;
+
+out:
+	cl_dbg(dev, cl, "end mei read rets = %zd\n", rets);
+	mutex_unlock(&dev->device_lock);
+	return rets;
+}
+
+/**
+ * mei_cl_vtag_by_fp - obtain the vtag by file pointer
+ *
+ * @cl: host client
+ * @fp: pointer to file structure
+ *
+ * Return: vtag value on success, otherwise 0
+ */
+static u8 mei_cl_vtag_by_fp(const struct mei_cl *cl, const struct file *fp)
+{
+	struct mei_cl_vtag *cl_vtag;
+
+	if (!fp)
+		return 0;
+
+	list_for_each_entry(cl_vtag, &cl->vtag_map, list)
+		if (cl_vtag->fp == fp)
+			return cl_vtag->vtag;
+	return 0;
+}
+
+/**
+ * mei_write - the write function.
+ *
+ * @file: pointer to file structure
+ * @ubuf: pointer to user buffer
+ * @length: buffer length
+ * @offset: data offset in buffer
+ *
+ * Return: >=0 data length on success , <0 on error
+ */
+static ssize_t mei_write(struct file *file, const char __user *ubuf,
+			 size_t length, loff_t *offset)
+{
+	struct mei_cl *cl = file->private_data;
+	struct mei_cl_cb *cb;
+	struct mei_device *dev;
+	ssize_t rets;
+
+	if (WARN_ON(!cl || !cl->dev))
+		return -ENODEV;
+
+	dev = cl->dev;
+
+	mutex_lock(&dev->device_lock);
+
+	if (dev->dev_state != MEI_DEV_ENABLED) {
+		rets = -ENODEV;
+		goto out;
+	}
+
+	if (!mei_cl_is_connected(cl)) {
+		cl_err(dev, cl, "is not connected");
+		rets = -ENODEV;
+		goto out;
+	}
+
+	if (!mei_me_cl_is_active(cl->me_cl)) {
+		rets = -ENOTTY;
+		goto out;
+	}
+
+	if (length > mei_cl_mtu(cl)) {
+		rets = -EFBIG;
+		goto out;
+	}
+
+	if (length == 0) {
+		rets = 0;
+		goto out;
+	}
+
+	while (cl->tx_cb_queued >= dev->tx_queue_limit) {
+		if (file->f_flags & O_NONBLOCK) {
+			rets = -EAGAIN;
+			goto out;
+		}
+		mutex_unlock(&dev->device_lock);
+		rets = wait_event_interruptible(cl->tx_wait,
+				cl->writing_state == MEI_WRITE_COMPLETE ||
+				(!mei_cl_is_connected(cl)));
+		mutex_lock(&dev->device_lock);
+		if (rets) {
+			if (signal_pending(current))
+				rets = -EINTR;
+			goto out;
+		}
+		if (!mei_cl_is_connected(cl)) {
+			rets = -ENODEV;
+			goto out;
+		}
+	}
+
+	cb = mei_cl_alloc_cb(cl, length, MEI_FOP_WRITE, file);
+	if (!cb) {
+		rets = -ENOMEM;
+		goto out;
+	}
+	cb->vtag = mei_cl_vtag_by_fp(cl, file);
+
+	rets = copy_from_user(cb->buf.data, ubuf, length);
+	if (rets) {
+		dev_dbg(dev->dev, "failed to copy data from userland\n");
+		rets = -EFAULT;
+		mei_io_cb_free(cb);
+		goto out;
+	}
+
+	rets = mei_cl_write(cl, cb);
+out:
+	mutex_unlock(&dev->device_lock);
+	return rets;
+}
+
+/**
+ * mei_ioctl_connect_client - the connect to fw client IOCTL function
+ *
+ * @file: private data of the file object
+ * @in_client_uuid: requested UUID for connection
+ * @client: IOCTL connect data, output parameters
+ *
+ * Locking: called under "dev->device_lock" lock
+ *
+ * Return: 0 on success, <0 on failure.
+ */
+static int mei_ioctl_connect_client(struct file *file,
+				    const uuid_le *in_client_uuid,
+				    struct mei_client *client)
+{
+	struct mei_device *dev;
+	struct mei_me_client *me_cl;
+	struct mei_cl *cl;
+	int rets;
+
+	cl = file->private_data;
+	dev = cl->dev;
+
+	if (cl->state != MEI_FILE_INITIALIZING &&
+	    cl->state != MEI_FILE_DISCONNECTED)
+		return  -EBUSY;
+
+	/* find ME client we're trying to connect to */
+	me_cl = mei_me_cl_by_uuid(dev, in_client_uuid);
+	if (!me_cl) {
+		dev_dbg(dev->dev, "Cannot connect to FW Client UUID = %pUl\n",
+			in_client_uuid);
+		rets = -ENOTTY;
+		goto end;
+	}
+
+	if (me_cl->props.fixed_address) {
+		bool forbidden = dev->override_fixed_address ?
+			 !dev->allow_fixed_address : !dev->hbm_f_fa_supported;
+		if (forbidden) {
+			dev_dbg(dev->dev, "Connection forbidden to FW Client UUID = %pUl\n",
+				in_client_uuid);
+			rets = -ENOTTY;
+			goto end;
+		}
+	}
+
+	dev_dbg(dev->dev, "Connect to FW Client ID = %d\n",
+			me_cl->client_id);
+	dev_dbg(dev->dev, "FW Client - Protocol Version = %d\n",
+			me_cl->props.protocol_version);
+	dev_dbg(dev->dev, "FW Client - Max Msg Len = %d\n",
+			me_cl->props.max_msg_length);
+
+	/* prepare the output buffer */
+	client->max_msg_length = me_cl->props.max_msg_length;
+	client->protocol_version = me_cl->props.protocol_version;
+	dev_dbg(dev->dev, "Can connect?\n");
+
+	rets = mei_cl_connect(cl, me_cl, file);
+
+end:
+	mei_me_cl_put(me_cl);
+	return rets;
+}
+
+/**
+ * mei_vt_support_check - check if client support vtags
+ *
+ * Locking: called under "dev->device_lock" lock
+ *
+ * @dev: mei_device
+ * @uuid: client UUID
+ *
+ * Return:
+ *	0 - supported
+ *	-ENOTTY - no such client
+ *	-EOPNOTSUPP - vtags are not supported by client
+ */
+static int mei_vt_support_check(struct mei_device *dev, const uuid_le *uuid)
+{
+	struct mei_me_client *me_cl;
+	int ret;
+
+	if (!dev->hbm_f_vt_supported)
+		return -EOPNOTSUPP;
+
+	me_cl = mei_me_cl_by_uuid(dev, uuid);
+	if (!me_cl) {
+		dev_dbg(dev->dev, "Cannot connect to FW Client UUID = %pUl\n",
+			uuid);
+		return -ENOTTY;
+	}
+	ret = me_cl->props.vt_supported ? 0 : -EOPNOTSUPP;
+	mei_me_cl_put(me_cl);
+
+	return ret;
+}
+
+/**
+ * mei_ioctl_connect_vtag - connect to fw client with vtag IOCTL function
+ *
+ * @file: private data of the file object
+ * @in_client_uuid: requested UUID for connection
+ * @client: IOCTL connect data, output parameters
+ * @vtag: vm tag
+ *
+ * Locking: called under "dev->device_lock" lock
+ *
+ * Return: 0 on success, <0 on failure.
+ */
+static int mei_ioctl_connect_vtag(struct file *file,
+				  const uuid_le *in_client_uuid,
+				  struct mei_client *client,
+				  u8 vtag)
+{
+	struct mei_device *dev;
+	struct mei_cl *cl;
+	struct mei_cl *pos;
+	struct mei_cl_vtag *cl_vtag;
+
+	cl = file->private_data;
+	dev = cl->dev;
+
+	dev_dbg(dev->dev, "FW Client %pUl vtag %d\n", in_client_uuid, vtag);
+
+	switch (cl->state) {
+	case MEI_FILE_DISCONNECTED:
+		if (mei_cl_vtag_by_fp(cl, file) != vtag) {
+			dev_err(dev->dev, "reconnect with different vtag\n");
+			return -EINVAL;
+		}
+		break;
+	case MEI_FILE_INITIALIZING:
+		/* malicious connect from another thread may push vtag */
+		if (!IS_ERR(mei_cl_fp_by_vtag(cl, vtag))) {
+			dev_err(dev->dev, "vtag already filled\n");
+			return -EINVAL;
+		}
+
+		list_for_each_entry(pos, &dev->file_list, link) {
+			if (pos == cl)
+				continue;
+			if (!pos->me_cl)
+				continue;
+
+			/* only search for same UUID */
+			if (uuid_le_cmp(*mei_cl_uuid(pos), *in_client_uuid))
+				continue;
+
+			/* if tag already exist try another fp */
+			if (!IS_ERR(mei_cl_fp_by_vtag(pos, vtag)))
+				continue;
+
+			/* replace cl with acquired one */
+			dev_dbg(dev->dev, "replacing with existing cl\n");
+			mei_cl_unlink(cl);
+			kfree(cl);
+			file->private_data = pos;
+			cl = pos;
+			break;
+		}
+
+		cl_vtag = mei_cl_vtag_alloc(file, vtag);
+		if (IS_ERR(cl_vtag))
+			return -ENOMEM;
+
+		list_add_tail(&cl_vtag->list, &cl->vtag_map);
+		break;
+	default:
+		return -EBUSY;
+	}
+
+	while (cl->state != MEI_FILE_INITIALIZING &&
+	       cl->state != MEI_FILE_DISCONNECTED &&
+	       cl->state != MEI_FILE_CONNECTED) {
+		mutex_unlock(&dev->device_lock);
+		wait_event_timeout(cl->wait,
+				   (cl->state == MEI_FILE_CONNECTED ||
+				    cl->state == MEI_FILE_DISCONNECTED ||
+				    cl->state == MEI_FILE_DISCONNECT_REQUIRED ||
+				    cl->state == MEI_FILE_DISCONNECT_REPLY),
+				   mei_secs_to_jiffies(MEI_CL_CONNECT_TIMEOUT));
+		mutex_lock(&dev->device_lock);
+	}
+
+	if (!mei_cl_is_connected(cl))
+		return mei_ioctl_connect_client(file, in_client_uuid, client);
+
+	client->max_msg_length = cl->me_cl->props.max_msg_length;
+	client->protocol_version = cl->me_cl->props.protocol_version;
+
+	return 0;
+}
+
+/**
+ * mei_ioctl_client_notify_request -
+ *     propagate event notification request to client
+ *
+ * @file: pointer to file structure
+ * @request: 0 - disable, 1 - enable
+ *
+ * Return: 0 on success , <0 on error
+ */
+static int mei_ioctl_client_notify_request(const struct file *file, u32 request)
+{
+	struct mei_cl *cl = file->private_data;
+
+	if (request != MEI_HBM_NOTIFICATION_START &&
+	    request != MEI_HBM_NOTIFICATION_STOP)
+		return -EINVAL;
+
+	return mei_cl_notify_request(cl, file, (u8)request);
+}
+
+/**
+ * mei_ioctl_client_notify_get -  wait for notification request
+ *
+ * @file: pointer to file structure
+ * @notify_get: 0 - disable, 1 - enable
+ *
+ * Return: 0 on success , <0 on error
+ */
+static int mei_ioctl_client_notify_get(const struct file *file, u32 *notify_get)
+{
+	struct mei_cl *cl = file->private_data;
+	bool notify_ev;
+	bool block = (file->f_flags & O_NONBLOCK) == 0;
+	int rets;
+
+	rets = mei_cl_notify_get(cl, block, &notify_ev);
+	if (rets)
+		return rets;
+
+	*notify_get = notify_ev ? 1 : 0;
+	return 0;
+}
+
+/**
+ * mei_ioctl - the IOCTL function
+ *
+ * @file: pointer to file structure
+ * @cmd: ioctl command
+ * @data: pointer to mei message structure
+ *
+ * Return: 0 on success , <0 on error
+ */
+static long mei_ioctl(struct file *file, unsigned int cmd, unsigned long data)
+{
+	struct mei_device *dev;
+	struct mei_cl *cl = file->private_data;
+	struct mei_connect_client_data conn;
+	struct mei_connect_client_data_vtag conn_vtag;
+	const uuid_le *cl_uuid;
+	struct mei_client *props;
+	u8 vtag;
+	u32 notify_get, notify_req;
+	int rets;
+
+
+	if (WARN_ON(!cl || !cl->dev))
+		return -ENODEV;
+
+	dev = cl->dev;
+
+	dev_dbg(dev->dev, "IOCTL cmd = 0x%x", cmd);
+
+	mutex_lock(&dev->device_lock);
+	if (dev->dev_state != MEI_DEV_ENABLED) {
+		rets = -ENODEV;
+		goto out;
+	}
+
+	switch (cmd) {
+	case IOCTL_MEI_CONNECT_CLIENT:
+		dev_dbg(dev->dev, ": IOCTL_MEI_CONNECT_CLIENT.\n");
+		if (copy_from_user(&conn, (char __user *)data, sizeof(conn))) {
+			dev_dbg(dev->dev, "failed to copy data from userland\n");
+			rets = -EFAULT;
+			goto out;
+		}
+		cl_uuid = &conn.in_client_uuid;
+		props = &conn.out_client_properties;
+		vtag = 0;
+
+		rets = mei_vt_support_check(dev, cl_uuid);
+		if (rets == -ENOTTY)
+			goto out;
+		if (!rets)
+			rets = mei_ioctl_connect_vtag(file, cl_uuid, props,
+						      vtag);
+		else
+			rets = mei_ioctl_connect_client(file, cl_uuid, props);
+		if (rets)
+			goto out;
+
+		/* if all is ok, copying the data back to user. */
+		if (copy_to_user((char __user *)data, &conn, sizeof(conn))) {
+			dev_dbg(dev->dev, "failed to copy data to userland\n");
+			rets = -EFAULT;
+			goto out;
+		}
+
+		break;
+
+	case IOCTL_MEI_CONNECT_CLIENT_VTAG:
+		dev_dbg(dev->dev, "IOCTL_MEI_CONNECT_CLIENT_VTAG\n");
+		if (copy_from_user(&conn_vtag, (char __user *)data,
+				   sizeof(conn_vtag))) {
+			dev_dbg(dev->dev, "failed to copy data from userland\n");
+			rets = -EFAULT;
+			goto out;
+		}
+
+		cl_uuid = &conn_vtag.connect.in_client_uuid;
+		props = &conn_vtag.out_client_properties;
+		vtag = conn_vtag.connect.vtag;
+
+		rets = mei_vt_support_check(dev, cl_uuid);
+		if (rets == -EOPNOTSUPP)
+			dev_dbg(dev->dev, "FW Client %pUl does not support vtags\n",
+				cl_uuid);
+		if (rets)
+			goto out;
+
+		if (!vtag) {
+			dev_dbg(dev->dev, "vtag can't be zero\n");
+			rets = -EINVAL;
+			goto out;
+		}
+
+		rets = mei_ioctl_connect_vtag(file, cl_uuid, props, vtag);
+		if (rets)
+			goto out;
+
+		/* if all is ok, copying the data back to user. */
+		if (copy_to_user((char __user *)data, &conn_vtag,
+				 sizeof(conn_vtag))) {
+			dev_dbg(dev->dev, "failed to copy data to userland\n");
+			rets = -EFAULT;
+			goto out;
+		}
+
+		break;
+
+	case IOCTL_MEI_NOTIFY_SET:
+		dev_dbg(dev->dev, ": IOCTL_MEI_NOTIFY_SET.\n");
+		if (copy_from_user(&notify_req,
+				   (char __user *)data, sizeof(notify_req))) {
+			dev_dbg(dev->dev, "failed to copy data from userland\n");
+			rets = -EFAULT;
+			goto out;
+		}
+		rets = mei_ioctl_client_notify_request(file, notify_req);
+		break;
+
+	case IOCTL_MEI_NOTIFY_GET:
+		dev_dbg(dev->dev, ": IOCTL_MEI_NOTIFY_GET.\n");
+		rets = mei_ioctl_client_notify_get(file, &notify_get);
+		if (rets)
+			goto out;
+
+		dev_dbg(dev->dev, "copy connect data to user\n");
+		if (copy_to_user((char __user *)data,
+				&notify_get, sizeof(notify_get))) {
+			dev_dbg(dev->dev, "failed to copy data to userland\n");
+			rets = -EFAULT;
+			goto out;
+
+		}
+		break;
+
+	default:
+		rets = -ENOIOCTLCMD;
+	}
+
+out:
+	mutex_unlock(&dev->device_lock);
+	return rets;
+}
+
+/**
+ * mei_poll - the poll function
+ *
+ * @file: pointer to file structure
+ * @wait: pointer to poll_table structure
+ *
+ * Return: poll mask
+ */
+static __poll_t mei_poll(struct file *file, poll_table *wait)
+{
+	__poll_t req_events = poll_requested_events(wait);
+	struct mei_cl *cl = file->private_data;
+	struct mei_device *dev;
+	__poll_t mask = 0;
+	bool notify_en;
+
+	if (WARN_ON(!cl || !cl->dev))
+		return EPOLLERR;
+
+	dev = cl->dev;
+
+	mutex_lock(&dev->device_lock);
+
+	notify_en = cl->notify_en && (req_events & EPOLLPRI);
+
+	if (dev->dev_state != MEI_DEV_ENABLED ||
+	    !mei_cl_is_connected(cl)) {
+		mask = EPOLLERR;
+		goto out;
+	}
+
+	if (notify_en) {
+		poll_wait(file, &cl->ev_wait, wait);
+		if (cl->notify_ev)
+			mask |= EPOLLPRI;
+	}
+
+	if (req_events & (EPOLLIN | EPOLLRDNORM)) {
+		poll_wait(file, &cl->rx_wait, wait);
+
+		if (mei_cl_read_cb(cl, file))
+			mask |= EPOLLIN | EPOLLRDNORM;
+		else
+			mei_cl_read_start(cl, mei_cl_mtu(cl), file);
+	}
+
+	if (req_events & (EPOLLOUT | EPOLLWRNORM)) {
+		poll_wait(file, &cl->tx_wait, wait);
+		if (cl->tx_cb_queued < dev->tx_queue_limit)
+			mask |= EPOLLOUT | EPOLLWRNORM;
+	}
+
+out:
+	mutex_unlock(&dev->device_lock);
+	return mask;
+}
+
+/**
+ * mei_cl_is_write_queued - check if the client has pending writes.
+ *
+ * @cl: writing host client
+ *
+ * Return: true if client is writing, false otherwise.
+ */
+static bool mei_cl_is_write_queued(struct mei_cl *cl)
+{
+	struct mei_device *dev = cl->dev;
+	struct mei_cl_cb *cb;
+
+	list_for_each_entry(cb, &dev->write_list, list)
+		if (cb->cl == cl)
+			return true;
+	list_for_each_entry(cb, &dev->write_waiting_list, list)
+		if (cb->cl == cl)
+			return true;
+	return false;
+}
+
+/**
+ * mei_fsync - the fsync handler
+ *
+ * @fp:       pointer to file structure
+ * @start:    unused
+ * @end:      unused
+ * @datasync: unused
+ *
+ * Return: 0 on success, -ENODEV if client is not connected
+ */
+static int mei_fsync(struct file *fp, loff_t start, loff_t end, int datasync)
+{
+	struct mei_cl *cl = fp->private_data;
+	struct mei_device *dev;
+	int rets;
+
+	if (WARN_ON(!cl || !cl->dev))
+		return -ENODEV;
+
+	dev = cl->dev;
+
+	mutex_lock(&dev->device_lock);
+
+	if (dev->dev_state != MEI_DEV_ENABLED || !mei_cl_is_connected(cl)) {
+		rets = -ENODEV;
+		goto out;
+	}
+
+	while (mei_cl_is_write_queued(cl)) {
+		mutex_unlock(&dev->device_lock);
+		rets = wait_event_interruptible(cl->tx_wait,
+				cl->writing_state == MEI_WRITE_COMPLETE ||
+				!mei_cl_is_connected(cl));
+		mutex_lock(&dev->device_lock);
+		if (rets) {
+			if (signal_pending(current))
+				rets = -EINTR;
+			goto out;
+		}
+		if (!mei_cl_is_connected(cl)) {
+			rets = -ENODEV;
+			goto out;
+		}
+	}
+	rets = 0;
+out:
+	mutex_unlock(&dev->device_lock);
+	return rets;
+}
+
+/**
+ * mei_fasync - asynchronous io support
+ *
+ * @fd: file descriptor
+ * @file: pointer to file structure
+ * @band: band bitmap
+ *
+ * Return: negative on error,
+ *         0 if it did no changes,
+ *         and positive a process was added or deleted
+ */
+static int mei_fasync(int fd, struct file *file, int band)
+{
+
+	struct mei_cl *cl = file->private_data;
+
+	if (!mei_cl_is_connected(cl))
+		return -ENODEV;
+
+	return fasync_helper(fd, file, band, &cl->ev_async);
+}
+
+/**
+ * trc_show - mei device trc attribute show method
+ *
+ * @device: device pointer
+ * @attr: attribute pointer
+ * @buf:  char out buffer
+ *
+ * Return: number of the bytes printed into buf or error
+ */
+static ssize_t trc_show(struct device *device,
+			struct device_attribute *attr, char *buf)
+{
+	struct mei_device *dev = dev_get_drvdata(device);
+	u32 trc;
+	int ret;
+
+	ret = mei_trc_status(dev, &trc);
+	if (ret)
+		return ret;
+	return sprintf(buf, "%08X\n", trc);
+}
+static DEVICE_ATTR_RO(trc);
+
+/**
+ * fw_status_show - mei device fw_status attribute show method
+ *
+ * @device: device pointer
+ * @attr: attribute pointer
+ * @buf:  char out buffer
+ *
+ * Return: number of the bytes printed into buf or error
+ */
+static ssize_t fw_status_show(struct device *device,
+		struct device_attribute *attr, char *buf)
+{
+	struct mei_device *dev = dev_get_drvdata(device);
+	struct mei_fw_status fw_status;
+	int err, i;
+	ssize_t cnt = 0;
+
+	mutex_lock(&dev->device_lock);
+	err = mei_fw_status(dev, &fw_status);
+	mutex_unlock(&dev->device_lock);
+	if (err) {
+		dev_err(device, "read fw_status error = %d\n", err);
+		return err;
+	}
+
+	for (i = 0; i < fw_status.count; i++)
+		cnt += scnprintf(buf + cnt, PAGE_SIZE - cnt, "%08X\n",
+				fw_status.status[i]);
+	return cnt;
+}
+static DEVICE_ATTR_RO(fw_status);
+
+/**
+ * hbm_ver_show - display HBM protocol version negotiated with FW
+ *
+ * @device: device pointer
+ * @attr: attribute pointer
+ * @buf:  char out buffer
+ *
+ * Return: number of the bytes printed into buf or error
+ */
+static ssize_t hbm_ver_show(struct device *device,
+			    struct device_attribute *attr, char *buf)
+{
+	struct mei_device *dev = dev_get_drvdata(device);
+	struct hbm_version ver;
+
+	mutex_lock(&dev->device_lock);
+	ver = dev->version;
+	mutex_unlock(&dev->device_lock);
+
+	return sprintf(buf, "%u.%u\n", ver.major_version, ver.minor_version);
+}
+static DEVICE_ATTR_RO(hbm_ver);
+
+/**
+ * hbm_ver_drv_show - display HBM protocol version advertised by driver
+ *
+ * @device: device pointer
+ * @attr: attribute pointer
+ * @buf:  char out buffer
+ *
+ * Return: number of the bytes printed into buf or error
+ */
+static ssize_t hbm_ver_drv_show(struct device *device,
+				struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%u.%u\n", HBM_MAJOR_VERSION, HBM_MINOR_VERSION);
+}
+static DEVICE_ATTR_RO(hbm_ver_drv);
+
+static ssize_t tx_queue_limit_show(struct device *device,
+				   struct device_attribute *attr, char *buf)
+{
+	struct mei_device *dev = dev_get_drvdata(device);
+	u8 size = 0;
+
+	mutex_lock(&dev->device_lock);
+	size = dev->tx_queue_limit;
+	mutex_unlock(&dev->device_lock);
+
+	return snprintf(buf, PAGE_SIZE, "%u\n", size);
+}
+
+static ssize_t tx_queue_limit_store(struct device *device,
+				    struct device_attribute *attr,
+				    const char *buf, size_t count)
+{
+	struct mei_device *dev = dev_get_drvdata(device);
+	u8 limit;
+	unsigned int inp;
+	int err;
+
+	err = kstrtouint(buf, 10, &inp);
+	if (err)
+		return err;
+	if (inp > MEI_TX_QUEUE_LIMIT_MAX || inp < MEI_TX_QUEUE_LIMIT_MIN)
+		return -EINVAL;
+	limit = inp;
+
+	mutex_lock(&dev->device_lock);
+	dev->tx_queue_limit = limit;
+	mutex_unlock(&dev->device_lock);
+
+	return count;
+}
+static DEVICE_ATTR_RW(tx_queue_limit);
+
+/**
+ * fw_ver_show - display ME FW version
+ *
+ * @device: device pointer
+ * @attr: attribute pointer
+ * @buf:  char out buffer
+ *
+ * Return: number of the bytes printed into buf or error
+ */
+static ssize_t fw_ver_show(struct device *device,
+			   struct device_attribute *attr, char *buf)
+{
+	struct mei_device *dev = dev_get_drvdata(device);
+	struct mei_fw_version *ver;
+	ssize_t cnt = 0;
+	int i;
+
+	ver = dev->fw_ver;
+
+	for (i = 0; i < MEI_MAX_FW_VER_BLOCKS; i++)
+		cnt += scnprintf(buf + cnt, PAGE_SIZE - cnt, "%u:%u.%u.%u.%u\n",
+				 ver[i].platform, ver[i].major, ver[i].minor,
+				 ver[i].hotfix, ver[i].buildno);
+	return cnt;
+}
+static DEVICE_ATTR_RO(fw_ver);
+
+/**
+ * dev_state_show - display device state
+ *
+ * @device: device pointer
+ * @attr: attribute pointer
+ * @buf:  char out buffer
+ *
+ * Return: number of the bytes printed into buf or error
+ */
+static ssize_t dev_state_show(struct device *device,
+			      struct device_attribute *attr, char *buf)
+{
+	struct mei_device *dev = dev_get_drvdata(device);
+	enum mei_dev_state dev_state;
+
+	mutex_lock(&dev->device_lock);
+	dev_state = dev->dev_state;
+	mutex_unlock(&dev->device_lock);
+
+	return sprintf(buf, "%s", mei_dev_state_str(dev_state));
+}
+static DEVICE_ATTR_RO(dev_state);
+
+/**
+ * dev_set_devstate: set to new device state and notify sysfs file.
+ *
+ * @dev: mei_device
+ * @state: new device state
+ */
+void mei_set_devstate(struct mei_device *dev, enum mei_dev_state state)
+{
+	struct device *clsdev;
+
+	if (dev->dev_state == state)
+		return;
+
+	dev->dev_state = state;
+
+	clsdev = class_find_device_by_devt(mei_class, dev->cdev.dev);
+	if (clsdev) {
+		sysfs_notify(&clsdev->kobj, NULL, "dev_state");
+		put_device(clsdev);
+	}
+}
+
+/**
+ * kind_show - display device kind
+ *
+ * @device: device pointer
+ * @attr: attribute pointer
+ * @buf: char out buffer
+ *
+ * Return: number of the bytes printed into buf or error
+ */
+static ssize_t kind_show(struct device *device,
+			 struct device_attribute *attr, char *buf)
+{
+	struct mei_device *dev = dev_get_drvdata(device);
+	ssize_t ret;
+
+	if (dev->kind)
+		ret = sprintf(buf, "%s\n", dev->kind);
+	else
+		ret = sprintf(buf, "%s\n", "mei");
+
+	return ret;
+}
+static DEVICE_ATTR_RO(kind);
+
+static struct attribute *mei_attrs[] = {
+	&dev_attr_fw_status.attr,
+	&dev_attr_hbm_ver.attr,
+	&dev_attr_hbm_ver_drv.attr,
+	&dev_attr_tx_queue_limit.attr,
+	&dev_attr_fw_ver.attr,
+	&dev_attr_dev_state.attr,
+	&dev_attr_trc.attr,
+	&dev_attr_kind.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(mei);
+
+/*
+ * file operations structure will be used for mei char device.
+ */
+static const struct file_operations mei_fops = {
+	.owner = THIS_MODULE,
+	.read = mei_read,
+	.unlocked_ioctl = mei_ioctl,
+	.compat_ioctl = compat_ptr_ioctl,
+	.open = mei_open,
+	.release = mei_release,
+	.write = mei_write,
+	.poll = mei_poll,
+	.fsync = mei_fsync,
+	.fasync = mei_fasync,
+	.llseek = no_llseek
+};
+
+/**
+ * mei_minor_get - obtain next free device minor number
+ *
+ * @dev:  device pointer
+ *
+ * Return: allocated minor, or -ENOSPC if no free minor left
+ */
+static int mei_minor_get(struct mei_device *dev)
+{
+	int ret;
+
+	mutex_lock(&mei_minor_lock);
+	ret = idr_alloc(&mei_idr, dev, 0, MEI_MAX_DEVS, GFP_KERNEL);
+	if (ret >= 0)
+		dev->minor = ret;
+	else if (ret == -ENOSPC)
+		dev_err(dev->dev, "too many mei devices\n");
+
+	mutex_unlock(&mei_minor_lock);
+	return ret;
+}
+
+/**
+ * mei_minor_free - mark device minor number as free
+ *
+ * @dev:  device pointer
+ */
+static void mei_minor_free(struct mei_device *dev)
+{
+	mutex_lock(&mei_minor_lock);
+	idr_remove(&mei_idr, dev->minor);
+	mutex_unlock(&mei_minor_lock);
+}
+
+int mei_register(struct mei_device *dev, struct device *parent)
+{
+	struct device *clsdev; /* class device */
+	int ret, devno;
+
+	ret = mei_minor_get(dev);
+	if (ret < 0)
+		return ret;
+
+	/* Fill in the data structures */
+	devno = MKDEV(MAJOR(mei_devt), dev->minor);
+	cdev_init(&dev->cdev, &mei_fops);
+	dev->cdev.owner = parent->driver->owner;
+
+	/* Add the device */
+	ret = cdev_add(&dev->cdev, devno, 1);
+	if (ret) {
+		dev_err(parent, "unable to add device %d:%d\n",
+			MAJOR(mei_devt), dev->minor);
+		goto err_dev_add;
+	}
+
+	clsdev = device_create_with_groups(mei_class, parent, devno,
+					   dev, mei_groups,
+					   "mei%d", dev->minor);
+
+	if (IS_ERR(clsdev)) {
+		dev_err(parent, "unable to create device %d:%d\n",
+			MAJOR(mei_devt), dev->minor);
+		ret = PTR_ERR(clsdev);
+		goto err_dev_create;
+	}
+
+	mei_dbgfs_register(dev, dev_name(clsdev));
+
+	return 0;
+
+err_dev_create:
+	cdev_del(&dev->cdev);
+err_dev_add:
+	mei_minor_free(dev);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mei_register);
+
+void mei_deregister(struct mei_device *dev)
+{
+	int devno;
+
+	devno = dev->cdev.dev;
+	cdev_del(&dev->cdev);
+
+	mei_dbgfs_deregister(dev);
+
+	device_destroy(mei_class, devno);
+
+	mei_minor_free(dev);
+}
+EXPORT_SYMBOL_GPL(mei_deregister);
+
+static int __init mei_init(void)
+{
+	int ret;
+
+	mei_class = class_create(THIS_MODULE, "mei");
+	if (IS_ERR(mei_class)) {
+		pr_err("couldn't create class\n");
+		ret = PTR_ERR(mei_class);
+		goto err;
+	}
+
+	ret = alloc_chrdev_region(&mei_devt, 0, MEI_MAX_DEVS, "mei");
+	if (ret < 0) {
+		pr_err("unable to allocate char dev region\n");
+		goto err_class;
+	}
+
+	ret = mei_cl_bus_init();
+	if (ret < 0) {
+		pr_err("unable to initialize bus\n");
+		goto err_chrdev;
+	}
+
+	return 0;
+
+err_chrdev:
+	unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
+err_class:
+	class_destroy(mei_class);
+err:
+	return ret;
+}
+
+static void __exit mei_exit(void)
+{
+	unregister_chrdev_region(mei_devt, MEI_MAX_DEVS);
+	class_destroy(mei_class);
+	mei_cl_bus_exit();
+}
+
+module_init(mei_init);
+module_exit(mei_exit);
+
+MODULE_AUTHOR("Intel Corporation");
+MODULE_DESCRIPTION("Intel(R) Management Engine Interface");
+MODULE_LICENSE("GPL v2");
+