text: // SPDX-License-Identifier: GPL-2.0
  /*
   * Copyright (c) 2012-2019, Intel Corporation. All rights reserved.
   * Intel Management Engine Interface (Intel MEI) Linux driver
   */
  
  #include <linux/module.h>
  #include <linux/device.h>
  #include <linux/kernel.h>
  #include <linux/sched/signal.h>
  #include <linux/init.h>
  #include <linux/errno.h>
  #include <linux/slab.h>
  #include <linux/mutex.h>
  #include <linux/interrupt.h>
  #include <linux/mei_cl_bus.h>
  
  #include "mei_dev.h"
  #include "client.h"
  
  #define to_mei_cl_driver(d) container_of(d, struct mei_cl_driver, driver)
  
  /**
   * __mei_cl_send - internal client send (write)
   *
   * @cl: host client
   * @buf: buffer to send
   * @length: buffer length
   * @vtag: virtual tag
   * @mode: sending mode
   *
   * Return: written size bytes or < 0 on error
   */
  ssize_t __mei_cl_send(struct mei_cl *cl, const u8 *buf, size_t length, u8 vtag,
  		      unsigned int mode)
  {
  	struct mei_device *bus;
  	struct mei_cl_cb *cb;
  	ssize_t rets;
  
  	if (WARN_ON(!cl || !cl->dev))
  		return -ENODEV;
  
  	bus = cl->dev;
  
  	mutex_lock(&bus->device_lock);
  	if (bus->dev_state != MEI_DEV_ENABLED &&
  	    bus->dev_state != MEI_DEV_POWERING_DOWN) {
  		rets = -ENODEV;
  		goto out;
  	}
  
  	if (!mei_cl_is_connected(cl)) {
  		rets = -ENODEV;
  		goto out;
  	}
  
  	/* Check if we have an ME client device */
  	if (!mei_me_cl_is_active(cl->me_cl)) {
  		rets = -ENOTTY;
  		goto out;
  	}
  
  	if (vtag) {
  		/* Check if vtag is supported by client */
  		rets = mei_cl_vt_support_check(cl);
  		if (rets)
  			goto out;
  	}
  
  	if (length > mei_cl_mtu(cl)) {
  		rets = -EFBIG;
  		goto out;
  	}
  
  	while (cl->tx_cb_queued >= bus->tx_queue_limit) {
  		mutex_unlock(&bus->device_lock);
  		rets = wait_event_interruptible(cl->tx_wait,
  				cl->writing_state == MEI_WRITE_COMPLETE ||
  				(!mei_cl_is_connected(cl)));
  		mutex_lock(&bus->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, NULL);
  	if (!cb) {
  		rets = -ENOMEM;
  		goto out;
  	}
  	cb->vtag = vtag;
  
  	cb->internal = !!(mode & MEI_CL_IO_TX_INTERNAL);
  	cb->blocking = !!(mode & MEI_CL_IO_TX_BLOCKING);
  	memcpy(cb->buf.data, buf, length);
  
  	rets = mei_cl_write(cl, cb);
  
  out:
  	mutex_unlock(&bus->device_lock);
  
  	return rets;
  }
  
  /**
   * __mei_cl_recv - internal client receive (read)
   *
   * @cl: host client
   * @buf: buffer to receive
   * @length: buffer length
   * @mode: io mode
   * @vtag: virtual tag
   * @timeout: recv timeout, 0 for infinite timeout
   *
   * Return: read size in bytes of < 0 on error
   */
  ssize_t __mei_cl_recv(struct mei_cl *cl, u8 *buf, size_t length, u8 *vtag,
  		      unsigned int mode, unsigned long timeout)
  {
  	struct mei_device *bus;
  	struct mei_cl_cb *cb;
  	size_t r_length;
  	ssize_t rets;
  	bool nonblock = !!(mode & MEI_CL_IO_RX_NONBLOCK);
  
  	if (WARN_ON(!cl || !cl->dev))
  		return -ENODEV;
  
  	bus = cl->dev;
  
  	mutex_lock(&bus->device_lock);
  	if (bus->dev_state != MEI_DEV_ENABLED &&
  	    bus->dev_state != MEI_DEV_POWERING_DOWN) {
  		rets = -ENODEV;
  		goto out;
  	}
  
  	cb = mei_cl_read_cb(cl, NULL);
  	if (cb)
  		goto copy;
  
  	rets = mei_cl_read_start(cl, length, NULL);
  	if (rets && rets != -EBUSY)
  		goto out;
  
  	if (nonblock) {
  		rets = -EAGAIN;
  		goto out;
  	}
  
  	/* wait on event only if there is no other waiter */
  	/* synchronized under device mutex */
  	if (!waitqueue_active(&cl->rx_wait)) {
  
  		mutex_unlock(&bus->device_lock);
  
  		if (timeout) {
  			rets = wait_event_interruptible_timeout
  					(cl->rx_wait,
  					mei_cl_read_cb(cl, NULL) ||
  					(!mei_cl_is_connected(cl)),
  					msecs_to_jiffies(timeout));
  			if (rets == 0)
  				return -ETIME;
  			if (rets < 0) {
  				if (signal_pending(current))
  					return -EINTR;
  				return -ERESTARTSYS;
  			}
  		} else {
  			if (wait_event_interruptible
  					(cl->rx_wait,
  					mei_cl_read_cb(cl, NULL) ||
  					(!mei_cl_is_connected(cl)))) {
  				if (signal_pending(current))
  					return -EINTR;
  				return -ERESTARTSYS;
  			}
  		}
  
  		mutex_lock(&bus->device_lock);
  
  		if (!mei_cl_is_connected(cl)) {
  			rets = -ENODEV;
  			goto out;
  		}
  	}
  
  	cb = mei_cl_read_cb(cl, NULL);
  	if (!cb) {
  		rets = 0;
  		goto out;
  	}
  
  copy:
  	if (cb->status) {
  		rets = cb->status;
  		goto free;
  	}
  
  	r_length = min_t(size_t, length, cb->buf_idx);
  	memcpy(buf, cb->buf.data, r_length);
  	rets = r_length;
  	if (vtag)
  		*vtag = cb->vtag;
  
  free:
  	mei_cl_del_rd_completed(cl, cb);
  out:
  	mutex_unlock(&bus->device_lock);
  
  	return rets;
  }
  
  /**
   * mei_cldev_send_vtag - me device send with vtag  (write)
   *
   * @cldev: me client device
   * @buf: buffer to send
   * @length: buffer length
   * @vtag: virtual tag
   *
   * Return:
   *  * written size in bytes
   *  * < 0 on error
   */
  
  ssize_t mei_cldev_send_vtag(struct mei_cl_device *cldev, const u8 *buf,
  			    size_t length, u8 vtag)
  {
  	struct mei_cl *cl = cldev->cl;
  
  	return __mei_cl_send(cl, buf, length, vtag, MEI_CL_IO_TX_BLOCKING);
  }
  EXPORT_SYMBOL_GPL(mei_cldev_send_vtag);
  
  /**
   * mei_cldev_recv_vtag - client receive with vtag (read)
   *
   * @cldev: me client device
   * @buf: buffer to receive
   * @length: buffer length
   * @vtag: virtual tag
   *
   * Return:
   * * read size in bytes
   * *  < 0 on error
   */
  
  ssize_t mei_cldev_recv_vtag(struct mei_cl_device *cldev, u8 *buf, size_t length,
  			    u8 *vtag)
  {
  	struct mei_cl *cl = cldev->cl;
  
  	return __mei_cl_recv(cl, buf, length, vtag, 0, 0);
  }
  EXPORT_SYMBOL_GPL(mei_cldev_recv_vtag);
  
  /**
   * mei_cldev_recv_nonblock_vtag - non block client receive with vtag (read)
   *
   * @cldev: me client device
   * @buf: buffer to receive
   * @length: buffer length
   * @vtag: virtual tag
   *
   * Return:
   * * read size in bytes
   * * -EAGAIN if function will block.
   * * < 0 on other error
   */
  ssize_t mei_cldev_recv_nonblock_vtag(struct mei_cl_device *cldev, u8 *buf,
  				     size_t length, u8 *vtag)
  {
  	struct mei_cl *cl = cldev->cl;
  
  	return __mei_cl_recv(cl, buf, length, vtag, MEI_CL_IO_RX_NONBLOCK, 0);
  }
  EXPORT_SYMBOL_GPL(mei_cldev_recv_nonblock_vtag);
  
  /**
   * mei_cldev_send - me device send  (write)
   *
   * @cldev: me client device
   * @buf: buffer to send
   * @length: buffer length
   *
   * Return:
   *  * written size in bytes
   *  * < 0 on error
   */
  ssize_t mei_cldev_send(struct mei_cl_device *cldev, const u8 *buf, size_t length)
  {
  	return mei_cldev_send_vtag(cldev, buf, length, 0);
  }
  EXPORT_SYMBOL_GPL(mei_cldev_send);
  
  /**
   * mei_cldev_recv - client receive (read)
   *
   * @cldev: me client device
   * @buf: buffer to receive
   * @length: buffer length
   *
   * Return: read size in bytes of < 0 on error
   */
  ssize_t mei_cldev_recv(struct mei_cl_device *cldev, u8 *buf, size_t length)
  {
  	return mei_cldev_recv_vtag(cldev, buf, length, NULL);
  }
  EXPORT_SYMBOL_GPL(mei_cldev_recv);
  
  /**
   * mei_cldev_recv_nonblock - non block client receive (read)
   *
   * @cldev: me client device
   * @buf: buffer to receive
   * @length: buffer length
   *
   * Return: read size in bytes of < 0 on error
   *         -EAGAIN if function will block.
   */
  ssize_t mei_cldev_recv_nonblock(struct mei_cl_device *cldev, u8 *buf,
  				size_t length)
  {
  	return mei_cldev_recv_nonblock_vtag(cldev, buf, length, NULL);
  }
  EXPORT_SYMBOL_GPL(mei_cldev_recv_nonblock);
  
  /**
   * mei_cl_bus_rx_work - dispatch rx event for a bus device
   *
   * @work: work
   */
  static void mei_cl_bus_rx_work(struct work_struct *work)
  {
  	struct mei_cl_device *cldev;
  	struct mei_device *bus;
  
  	cldev = container_of(work, struct mei_cl_device, rx_work);
  
  	bus = cldev->bus;
  
  	if (cldev->rx_cb)
  		cldev->rx_cb(cldev);
  
  	mutex_lock(&bus->device_lock);
  	if (mei_cl_is_connected(cldev->cl))
  		mei_cl_read_start(cldev->cl, mei_cl_mtu(cldev->cl), NULL);
  	mutex_unlock(&bus->device_lock);
  }
  
  /**
   * mei_cl_bus_notif_work - dispatch FW notif event for a bus device
   *
   * @work: work
   */
  static void mei_cl_bus_notif_work(struct work_struct *work)
  {
  	struct mei_cl_device *cldev;
  
  	cldev = container_of(work, struct mei_cl_device, notif_work);
  
  	if (cldev->notif_cb)
  		cldev->notif_cb(cldev);
  }
  
  /**
   * mei_cl_bus_notify_event - schedule notify cb on bus client
   *
   * @cl: host client
   *
   * Return: true if event was scheduled
   *         false if the client is not waiting for event
   */
  bool mei_cl_bus_notify_event(struct mei_cl *cl)
  {
  	struct mei_cl_device *cldev = cl->cldev;
  
  	if (!cldev || !cldev->notif_cb)
  		return false;
  
  	if (!cl->notify_ev)
  		return false;
  
  	schedule_work(&cldev->notif_work);
  
  	cl->notify_ev = false;
  
  	return true;
  }
  
  /**
   * mei_cl_bus_rx_event - schedule rx event
   *
   * @cl: host client
   *
   * Return: true if event was scheduled
   *         false if the client is not waiting for event
   */
  bool mei_cl_bus_rx_event(struct mei_cl *cl)
  {
  	struct mei_cl_device *cldev = cl->cldev;
  
  	if (!cldev || !cldev->rx_cb)
  		return false;
  
  	schedule_work(&cldev->rx_work);
  
  	return true;
  }
  
  /**
   * mei_cldev_register_rx_cb - register Rx event callback
   *
   * @cldev: me client devices
   * @rx_cb: callback function
   *
   * Return: 0 on success
   *         -EALREADY if an callback is already registered
   *         <0 on other errors
   */
  int mei_cldev_register_rx_cb(struct mei_cl_device *cldev, mei_cldev_cb_t rx_cb)
  {
  	struct mei_device *bus = cldev->bus;
  	int ret;
  
  	if (!rx_cb)
  		return -EINVAL;
  	if (cldev->rx_cb)
  		return -EALREADY;
  
  	cldev->rx_cb = rx_cb;
  	INIT_WORK(&cldev->rx_work, mei_cl_bus_rx_work);
  
  	mutex_lock(&bus->device_lock);
  	if (mei_cl_is_connected(cldev->cl))
  		ret = mei_cl_read_start(cldev->cl, mei_cl_mtu(cldev->cl), NULL);
  	else
  		ret = -ENODEV;
  	mutex_unlock(&bus->device_lock);
  	if (ret && ret != -EBUSY) {
  		cancel_work_sync(&cldev->rx_work);
  		cldev->rx_cb = NULL;
  		return ret;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(mei_cldev_register_rx_cb);
  
  /**
   * mei_cldev_register_notif_cb - register FW notification event callback
   *
   * @cldev: me client devices
   * @notif_cb: callback function
   *
   * Return: 0 on success
   *         -EALREADY if an callback is already registered
   *         <0 on other errors
   */
  int mei_cldev_register_notif_cb(struct mei_cl_device *cldev,
  				mei_cldev_cb_t notif_cb)
  {
  	struct mei_device *bus = cldev->bus;
  	int ret;
  
  	if (!notif_cb)
  		return -EINVAL;
  
  	if (cldev->notif_cb)
  		return -EALREADY;
  
  	cldev->notif_cb = notif_cb;
  	INIT_WORK(&cldev->notif_work, mei_cl_bus_notif_work);
  
  	mutex_lock(&bus->device_lock);
  	ret = mei_cl_notify_request(cldev->cl, NULL, 1);
  	mutex_unlock(&bus->device_lock);
  	if (ret) {
  		cancel_work_sync(&cldev->notif_work);
  		cldev->notif_cb = NULL;
  		return ret;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(mei_cldev_register_notif_cb);
  
  /**
   * mei_cldev_get_drvdata - driver data getter
   *
   * @cldev: mei client device
   *
   * Return: driver private data
   */
  void *mei_cldev_get_drvdata(const struct mei_cl_device *cldev)
  {
  	return dev_get_drvdata(&cldev->dev);
  }
  EXPORT_SYMBOL_GPL(mei_cldev_get_drvdata);
  
  /**
   * mei_cldev_set_drvdata - driver data setter
   *
   * @cldev: mei client device
   * @data: data to store
   */
  void mei_cldev_set_drvdata(struct mei_cl_device *cldev, void *data)
  {
  	dev_set_drvdata(&cldev->dev, data);
  }
  EXPORT_SYMBOL_GPL(mei_cldev_set_drvdata);
  
  /**
   * mei_cldev_uuid - return uuid of the underlying me client
   *
   * @cldev: mei client device
   *
   * Return: me client uuid
   */
  const uuid_le *mei_cldev_uuid(const struct mei_cl_device *cldev)
  {
  	return mei_me_cl_uuid(cldev->me_cl);
  }
  EXPORT_SYMBOL_GPL(mei_cldev_uuid);
  
  /**
   * mei_cldev_ver - return protocol version of the underlying me client
   *
   * @cldev: mei client device
   *
   * Return: me client protocol version
   */
  u8 mei_cldev_ver(const struct mei_cl_device *cldev)
  {
  	return mei_me_cl_ver(cldev->me_cl);
  }
  EXPORT_SYMBOL_GPL(mei_cldev_ver);
  
  /**
   * mei_cldev_enabled - check whether the device is enabled
   *
   * @cldev: mei client device
   *
   * Return: true if me client is initialized and connected
   */
  bool mei_cldev_enabled(const struct mei_cl_device *cldev)
  {
  	return mei_cl_is_connected(cldev->cl);
  }
  EXPORT_SYMBOL_GPL(mei_cldev_enabled);
  
  /**
   * mei_cl_bus_module_get - acquire module of the underlying
   *    hw driver.
   *
   * @cldev: mei client device
   *
   * Return: true on success; false if the module was removed.
   */
  static bool mei_cl_bus_module_get(struct mei_cl_device *cldev)
  {
  	return try_module_get(cldev->bus->dev->driver->owner);
  }
  
  /**
   * mei_cl_bus_module_put -  release the underlying hw module.
   *
   * @cldev: mei client device
   */
  static void mei_cl_bus_module_put(struct mei_cl_device *cldev)
  {
  	module_put(cldev->bus->dev->driver->owner);
  }
  
  /**
   * mei_cl_bus_vtag - get bus vtag entry wrapper
   *     The tag for bus client is always first.
   *
   * @cl: host client
   *
   * Return: bus vtag or NULL
   */
  static inline struct mei_cl_vtag *mei_cl_bus_vtag(struct mei_cl *cl)
  {
  	return list_first_entry_or_null(&cl->vtag_map,
  					struct mei_cl_vtag, list);
  }
  
  /**
   * mei_cl_bus_vtag_alloc - add bus client entry to vtag map
   *
   * @cldev: me client device
   *
   * Return:
   * * 0 on success
   * * -ENOMEM if memory allocation failed
   */
  static int mei_cl_bus_vtag_alloc(struct mei_cl_device *cldev)
  {
  	struct mei_cl *cl = cldev->cl;
  	struct mei_cl_vtag *cl_vtag;
  
  	/*
  	 * Bail out if the client does not supports vtags
  	 * or has already allocated one
  	 */
  	if (mei_cl_vt_support_check(cl) || mei_cl_bus_vtag(cl))
  		return 0;
  
  	cl_vtag = mei_cl_vtag_alloc(NULL, 0);
  	if (IS_ERR(cl_vtag))
  		return -ENOMEM;
  
  	list_add_tail(&cl_vtag->list, &cl->vtag_map);
  
  	return 0;
  }
  
  /**
   * mei_cl_bus_vtag_free - remove the bus entry from vtag map
   *
   * @cldev: me client device
   */
  static void mei_cl_bus_vtag_free(struct mei_cl_device *cldev)
  {
  	struct mei_cl *cl = cldev->cl;
  	struct mei_cl_vtag *cl_vtag;
  
  	cl_vtag = mei_cl_bus_vtag(cl);
  	if (!cl_vtag)
  		return;
  
  	list_del(&cl_vtag->list);
  	kfree(cl_vtag);
  }
  
  /**
   * mei_cldev_enable - enable me client device
   *     create connection with me client
   *
   * @cldev: me client device
   *
   * Return: 0 on success and < 0 on error
   */
  int mei_cldev_enable(struct mei_cl_device *cldev)
  {
  	struct mei_device *bus = cldev->bus;
  	struct mei_cl *cl;
  	int ret;
  
  	cl = cldev->cl;
  
  	mutex_lock(&bus->device_lock);
  	if (cl->state == MEI_FILE_UNINITIALIZED) {
  		ret = mei_cl_link(cl);
  		if (ret)
  			goto out;
  		/* update pointers */
  		cl->cldev = cldev;
  	}
  
  	if (mei_cl_is_connected(cl)) {
  		ret = 0;
  		goto out;
  	}
  
  	if (!mei_me_cl_is_active(cldev->me_cl)) {
  		dev_err(&cldev->dev, "me client is not active\n");
  		ret = -ENOTTY;
  		goto out;
  	}
  
  	ret = mei_cl_bus_vtag_alloc(cldev);
  	if (ret)
  		goto out;
  
  	ret = mei_cl_connect(cl, cldev->me_cl, NULL);
  	if (ret < 0) {
  		dev_err(&cldev->dev, "cannot connect\n");
  		mei_cl_bus_vtag_free(cldev);
  	}
  
  out:
  	mutex_unlock(&bus->device_lock);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(mei_cldev_enable);
  
  /**
   * mei_cldev_unregister_callbacks - internal wrapper for unregistering
   *  callbacks.
   *
   * @cldev: client device
   */
  static void mei_cldev_unregister_callbacks(struct mei_cl_device *cldev)
  {
  	if (cldev->rx_cb) {
  		cancel_work_sync(&cldev->rx_work);
  		cldev->rx_cb = NULL;
  	}
  
  	if (cldev->notif_cb) {
  		cancel_work_sync(&cldev->notif_work);
  		cldev->notif_cb = NULL;
  	}
  }
  
  /**
   * mei_cldev_disable - disable me client device
   *     disconnect form the me client
   *
   * @cldev: me client device
   *
   * Return: 0 on success and < 0 on error
   */
  int mei_cldev_disable(struct mei_cl_device *cldev)
  {
  	struct mei_device *bus;
  	struct mei_cl *cl;
  	int err;
  
  	if (!cldev)
  		return -ENODEV;
  
  	cl = cldev->cl;
  
  	bus = cldev->bus;
  
  	mei_cldev_unregister_callbacks(cldev);
  
  	mutex_lock(&bus->device_lock);
  
  	mei_cl_bus_vtag_free(cldev);
  
  	if (!mei_cl_is_connected(cl)) {
  		dev_dbg(bus->dev, "Already disconnected\n");
  		err = 0;
  		goto out;
  	}
  
  	err = mei_cl_disconnect(cl);
  	if (err < 0)
  		dev_err(bus->dev, "Could not disconnect from the ME client\n");
  
  out:
  	/* Flush queues and remove any pending read */
  	mei_cl_flush_queues(cl, NULL);
  	mei_cl_unlink(cl);
  
  	mutex_unlock(&bus->device_lock);
  	return err;
  }
  EXPORT_SYMBOL_GPL(mei_cldev_disable);
  
  /**
   * mei_cl_device_find - find matching entry in the driver id table
   *
   * @cldev: me client device
   * @cldrv: me client driver
   *
   * Return: id on success; NULL if no id is matching
   */
  static const
  struct mei_cl_device_id *mei_cl_device_find(const struct mei_cl_device *cldev,
  					    const struct mei_cl_driver *cldrv)
  {
  	const struct mei_cl_device_id *id;
  	const uuid_le *uuid;
  	u8 version;
  	bool match;
  
  	uuid = mei_me_cl_uuid(cldev->me_cl);
  	version = mei_me_cl_ver(cldev->me_cl);
  
  	id = cldrv->id_table;
  	while (uuid_le_cmp(NULL_UUID_LE, id->uuid)) {
  		if (!uuid_le_cmp(*uuid, id->uuid)) {
  			match = true;
  
  			if (cldev->name[0])
  				if (strncmp(cldev->name, id->name,
  					    sizeof(id->name)))
  					match = false;
  
  			if (id->version != MEI_CL_VERSION_ANY)
  				if (id->version != version)
  					match = false;
  			if (match)
  				return id;
  		}
  
  		id++;
  	}
  
  	return NULL;
  }
  
  /**
   * mei_cl_device_match  - device match function
   *
   * @dev: device
   * @drv: driver
   *
   * Return:  1 if matching device was found 0 otherwise
   */
  static int mei_cl_device_match(struct device *dev, struct device_driver *drv)
  {
  	const struct mei_cl_device *cldev = to_mei_cl_device(dev);
  	const struct mei_cl_driver *cldrv = to_mei_cl_driver(drv);
  	const struct mei_cl_device_id *found_id;
  
  	if (!cldev)
  		return 0;
  
  	if (!cldev->do_match)
  		return 0;
  
  	if (!cldrv || !cldrv->id_table)
  		return 0;
  
  	found_id = mei_cl_device_find(cldev, cldrv);
  	if (found_id)
  		return 1;
  
  	return 0;
  }
  
  /**
   * mei_cl_device_probe - bus probe function
   *
   * @dev: device
   *
   * Return:  0 on success; < 0 otherwise
   */
  static int mei_cl_device_probe(struct device *dev)
  {
  	struct mei_cl_device *cldev;
  	struct mei_cl_driver *cldrv;
  	const struct mei_cl_device_id *id;
  	int ret;
  
  	cldev = to_mei_cl_device(dev);
  	cldrv = to_mei_cl_driver(dev->driver);
  
  	if (!cldev)
  		return 0;
  
  	if (!cldrv || !cldrv->probe)
  		return -ENODEV;
  
  	id = mei_cl_device_find(cldev, cldrv);
  	if (!id)
  		return -ENODEV;
  
  	if (!mei_cl_bus_module_get(cldev)) {
  		dev_err(&cldev->dev, "get hw module failed");
  		return -ENODEV;
  	}
  
  	ret = cldrv->probe(cldev, id);
  	if (ret) {
  		mei_cl_bus_module_put(cldev);
  		return ret;
  	}
  
  	__module_get(THIS_MODULE);
  	return 0;
  }
  
  /**
   * mei_cl_device_remove - remove device from the bus
   *
   * @dev: device
   *
   * Return:  0 on success; < 0 otherwise
   */
  static void mei_cl_device_remove(struct device *dev)
  {
  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
  	struct mei_cl_driver *cldrv = to_mei_cl_driver(dev->driver);
  
  	if (cldrv->remove)
  		cldrv->remove(cldev);
  
  	mei_cldev_unregister_callbacks(cldev);
  
  	mei_cl_bus_module_put(cldev);
  	module_put(THIS_MODULE);
  }
  
  static ssize_t name_show(struct device *dev, struct device_attribute *a,
  			     char *buf)
  {
  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
  
  	return scnprintf(buf, PAGE_SIZE, "%s", cldev->name);
  }
  static DEVICE_ATTR_RO(name);
  
  static ssize_t uuid_show(struct device *dev, struct device_attribute *a,
  			     char *buf)
  {
  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
  	const uuid_le *uuid = mei_me_cl_uuid(cldev->me_cl);
  
  	return sprintf(buf, "%pUl", uuid);
  }
  static DEVICE_ATTR_RO(uuid);
  
  static ssize_t version_show(struct device *dev, struct device_attribute *a,
  			     char *buf)
  {
  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
  	u8 version = mei_me_cl_ver(cldev->me_cl);
  
  	return sprintf(buf, "%02X", version);
  }
  static DEVICE_ATTR_RO(version);
  
  static ssize_t modalias_show(struct device *dev, struct device_attribute *a,
  			     char *buf)
  {
  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
  	const uuid_le *uuid = mei_me_cl_uuid(cldev->me_cl);
  	u8 version = mei_me_cl_ver(cldev->me_cl);
  
  	return scnprintf(buf, PAGE_SIZE, "mei:%s:%pUl:%02X:",
  			 cldev->name, uuid, version);
  }
  static DEVICE_ATTR_RO(modalias);
  
  static ssize_t max_conn_show(struct device *dev, struct device_attribute *a,
  			     char *buf)
  {
  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
  	u8 maxconn = mei_me_cl_max_conn(cldev->me_cl);
  
  	return sprintf(buf, "%d", maxconn);
  }
  static DEVICE_ATTR_RO(max_conn);
  
  static ssize_t fixed_show(struct device *dev, struct device_attribute *a,
  			  char *buf)
  {
  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
  	u8 fixed = mei_me_cl_fixed(cldev->me_cl);
  
  	return sprintf(buf, "%d", fixed);
  }
  static DEVICE_ATTR_RO(fixed);
  
  static ssize_t vtag_show(struct device *dev, struct device_attribute *a,
  			 char *buf)
  {
  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
  	bool vt = mei_me_cl_vt(cldev->me_cl);
  
  	return sprintf(buf, "%d", vt);
  }
  static DEVICE_ATTR_RO(vtag);
  
  static ssize_t max_len_show(struct device *dev, struct device_attribute *a,
  			    char *buf)
  {
  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
  	u32 maxlen = mei_me_cl_max_len(cldev->me_cl);
  
  	return sprintf(buf, "%u", maxlen);
  }
  static DEVICE_ATTR_RO(max_len);
  
  static struct attribute *mei_cldev_attrs[] = {
  	&dev_attr_name.attr,
  	&dev_attr_uuid.attr,
  	&dev_attr_version.attr,
  	&dev_attr_modalias.attr,
  	&dev_attr_max_conn.attr,
  	&dev_attr_fixed.attr,
  	&dev_attr_vtag.attr,
  	&dev_attr_max_len.attr,
  	NULL,
  };
  ATTRIBUTE_GROUPS(mei_cldev);
  
  /**
   * mei_cl_device_uevent - me client bus uevent handler
   *
   * @dev: device
   * @env: uevent kobject
   *
   * Return: 0 on success -ENOMEM on when add_uevent_var fails
   */
  static int mei_cl_device_uevent(struct device *dev, struct kobj_uevent_env *env)
  {
  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
  	const uuid_le *uuid = mei_me_cl_uuid(cldev->me_cl);
  	u8 version = mei_me_cl_ver(cldev->me_cl);
  
  	if (add_uevent_var(env, "MEI_CL_VERSION=%d", version))
  		return -ENOMEM;
  
  	if (add_uevent_var(env, "MEI_CL_UUID=%pUl", uuid))
  		return -ENOMEM;
  
  	if (add_uevent_var(env, "MEI_CL_NAME=%s", cldev->name))
  		return -ENOMEM;
  
  	if (add_uevent_var(env, "MODALIAS=mei:%s:%pUl:%02X:",
  			   cldev->name, uuid, version))
  		return -ENOMEM;
  
  	return 0;
  }
  
  static struct bus_type mei_cl_bus_type = {
  	.name		= "mei",
  	.dev_groups	= mei_cldev_groups,
  	.match		= mei_cl_device_match,
  	.probe		= mei_cl_device_probe,
  	.remove		= mei_cl_device_remove,
  	.uevent		= mei_cl_device_uevent,
  };
  
  static struct mei_device *mei_dev_bus_get(struct mei_device *bus)
  {
  	if (bus)
  		get_device(bus->dev);
  
  	return bus;
  }
  
  static void mei_dev_bus_put(struct mei_device *bus)
  {
  	if (bus)
  		put_device(bus->dev);
  }
  
  static void mei_cl_bus_dev_release(struct device *dev)
  {
  	struct mei_cl_device *cldev = to_mei_cl_device(dev);
  
  	if (!cldev)
  		return;
  
  	mei_me_cl_put(cldev->me_cl);
  	mei_dev_bus_put(cldev->bus);
  	mei_cl_unlink(cldev->cl);
  	kfree(cldev->cl);
  	kfree(cldev);
  }
  
  static const struct device_type mei_cl_device_type = {
  	.release = mei_cl_bus_dev_release,
  };
  
  /**
   * mei_cl_bus_set_name - set device name for me client device
   *  <controller>-<client device>
   *  Example: 0000:00:16.0-55213584-9a29-4916-badf-0fb7ed682aeb
   *
   * @cldev: me client device
   */
  static inline void mei_cl_bus_set_name(struct mei_cl_device *cldev)
  {
  	dev_set_name(&cldev->dev, "%s-%pUl",
  		     dev_name(cldev->bus->dev),
  		     mei_me_cl_uuid(cldev->me_cl));
  }
  
  /**
   * mei_cl_bus_dev_alloc - initialize and allocate mei client device
   *
   * @bus: mei device
   * @me_cl: me client
   *
   * Return: allocated device structur or NULL on allocation failure
   */
  static struct mei_cl_device *mei_cl_bus_dev_alloc(struct mei_device *bus,
  						  struct mei_me_client *me_cl)
  {
  	struct mei_cl_device *cldev;
  	struct mei_cl *cl;
  
  	cldev = kzalloc(sizeof(*cldev), GFP_KERNEL);
  	if (!cldev)
  		return NULL;
  
  	cl = mei_cl_allocate(bus);
  	if (!cl) {
  		kfree(cldev);
  		return NULL;
  	}
  
  	device_initialize(&cldev->dev);
  	cldev->dev.parent = bus->dev;
  	cldev->dev.bus    = &mei_cl_bus_type;
  	cldev->dev.type   = &mei_cl_device_type;
  	cldev->bus        = mei_dev_bus_get(bus);
  	cldev->me_cl      = mei_me_cl_get(me_cl);
  	cldev->cl         = cl;
  	mei_cl_bus_set_name(cldev);
  	cldev->is_added   = 0;
  	INIT_LIST_HEAD(&cldev->bus_list);
  
  	return cldev;
  }
  
  /**
   * mei_cl_bus_dev_setup - setup me client device
   *    run fix up routines and set the device name
   *
   * @bus: mei device
   * @cldev: me client device
   *
   * Return: true if the device is eligible for enumeration
   */
  static bool mei_cl_bus_dev_setup(struct mei_device *bus,
  				 struct mei_cl_device *cldev)
  {
  	cldev->do_match = 1;
  	mei_cl_bus_dev_fixup(cldev);
  
  	/* the device name can change during fix up */
  	if (cldev->do_match)
  		mei_cl_bus_set_name(cldev);
  
  	return cldev->do_match == 1;
  }
  
  /**
   * mei_cl_bus_dev_add - add me client devices
   *
   * @cldev: me client device
   *
   * Return: 0 on success; < 0 on failre
   */
  static int mei_cl_bus_dev_add(struct mei_cl_device *cldev)
  {
  	int ret;
  
  	dev_dbg(cldev->bus->dev, "adding %pUL:%02X\n",
  		mei_me_cl_uuid(cldev->me_cl),
  		mei_me_cl_ver(cldev->me_cl));
  	ret = device_add(&cldev->dev);
  	if (!ret)
  		cldev->is_added = 1;
  
  	return ret;
  }
  
  /**
   * mei_cl_bus_dev_stop - stop the driver
   *
   * @cldev: me client device
   */
  static void mei_cl_bus_dev_stop(struct mei_cl_device *cldev)
  {
  	if (cldev->is_added)
  		device_release_driver(&cldev->dev);
  }
  
  /**
   * mei_cl_bus_dev_destroy - destroy me client devices object
   *
   * @cldev: me client device
   *
   * Locking: called under "dev->cl_bus_lock" lock
   */
  static void mei_cl_bus_dev_destroy(struct mei_cl_device *cldev)
  {
  
  	WARN_ON(!mutex_is_locked(&cldev->bus->cl_bus_lock));
  
  	if (!cldev->is_added)
  		return;
  
  	device_del(&cldev->dev);
  
  	list_del_init(&cldev->bus_list);
  
  	cldev->is_added = 0;
  	put_device(&cldev->dev);
  }
  
  /**
   * mei_cl_bus_remove_device - remove a devices form the bus
   *
   * @cldev: me client device
   */
  static void mei_cl_bus_remove_device(struct mei_cl_device *cldev)
  {
  	mei_cl_bus_dev_stop(cldev);
  	mei_cl_bus_dev_destroy(cldev);
  }
  
  /**
   * mei_cl_bus_remove_devices - remove all devices form the bus
   *
   * @bus: mei device
   */
  void mei_cl_bus_remove_devices(struct mei_device *bus)
  {
  	struct mei_cl_device *cldev, *next;
  
  	mutex_lock(&bus->cl_bus_lock);
  	list_for_each_entry_safe(cldev, next, &bus->device_list, bus_list)
  		mei_cl_bus_remove_device(cldev);
  	mutex_unlock(&bus->cl_bus_lock);
  }
  
  
  /**
   * mei_cl_bus_dev_init - allocate and initializes an mei client devices
   *     based on me client
   *
   * @bus: mei device
   * @me_cl: me client
   *
   * Locking: called under "dev->cl_bus_lock" lock
   */
  static void mei_cl_bus_dev_init(struct mei_device *bus,
  				struct mei_me_client *me_cl)
  {
  	struct mei_cl_device *cldev;
  
  	WARN_ON(!mutex_is_locked(&bus->cl_bus_lock));
  
  	dev_dbg(bus->dev, "initializing %pUl", mei_me_cl_uuid(me_cl));
  
  	if (me_cl->bus_added)
  		return;
  
  	cldev = mei_cl_bus_dev_alloc(bus, me_cl);
  	if (!cldev)
  		return;
  
  	me_cl->bus_added = true;
  	list_add_tail(&cldev->bus_list, &bus->device_list);
  
  }
  
  /**
   * mei_cl_bus_rescan - scan me clients list and add create
   *    devices for eligible clients
   *
   * @bus: mei device
   */
  static void mei_cl_bus_rescan(struct mei_device *bus)
  {
  	struct mei_cl_device *cldev, *n;
  	struct mei_me_client *me_cl;
  
  	mutex_lock(&bus->cl_bus_lock);
  
  	down_read(&bus->me_clients_rwsem);
  	list_for_each_entry(me_cl, &bus->me_clients, list)
  		mei_cl_bus_dev_init(bus, me_cl);
  	up_read(&bus->me_clients_rwsem);
  
  	list_for_each_entry_safe(cldev, n, &bus->device_list, bus_list) {
  
  		if (!mei_me_cl_is_active(cldev->me_cl)) {
  			mei_cl_bus_remove_device(cldev);
  			continue;
  		}
  
  		if (cldev->is_added)
  			continue;
  
  		if (mei_cl_bus_dev_setup(bus, cldev))
  			mei_cl_bus_dev_add(cldev);
  		else {
  			list_del_init(&cldev->bus_list);
  			put_device(&cldev->dev);
  		}
  	}
  	mutex_unlock(&bus->cl_bus_lock);
  
  	dev_dbg(bus->dev, "rescan end");
  }
  
  void mei_cl_bus_rescan_work(struct work_struct *work)
  {
  	struct mei_device *bus =
  		container_of(work, struct mei_device, bus_rescan_work);
  
  	mei_cl_bus_rescan(bus);
  }
  
  int __mei_cldev_driver_register(struct mei_cl_driver *cldrv,
  				struct module *owner)
  {
  	int err;
  
  	cldrv->driver.name = cldrv->name;
  	cldrv->driver.owner = owner;
  	cldrv->driver.bus = &mei_cl_bus_type;
  
  	err = driver_register(&cldrv->driver);
  	if (err)
  		return err;
  
  	pr_debug("mei: driver [%s] registered\n", cldrv->driver.name);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(__mei_cldev_driver_register);
  
  void mei_cldev_driver_unregister(struct mei_cl_driver *cldrv)
  {
  	driver_unregister(&cldrv->driver);
  
  	pr_debug("mei: driver [%s] unregistered\n", cldrv->driver.name);
  }
  EXPORT_SYMBOL_GPL(mei_cldev_driver_unregister);
  
  
  int __init mei_cl_bus_init(void)
  {
  	return bus_register(&mei_cl_bus_type);
  }
  
  void __exit mei_cl_bus_exit(void)
  {
  	bus_unregister(&mei_cl_bus_type);
  }
  