// SPDX-License-Identifier: GPL-2.0

  /*

   * Thunderbolt driver - control channel and configuration commands

   *
   * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>

   * Copyright (C) 2018, Intel Corporation

   */
  
  #include <linux/crc32.h>

  #include <linux/delay.h>

  #include <linux/slab.h>
  #include <linux/pci.h>
  #include <linux/dmapool.h>
  #include <linux/workqueue.h>

  
  #include "ctl.h"

  #define TB_CTL_RX_PKG_COUNT	10
  #define TB_CTL_RETRIES		4

  
  /**
   * struct tb_cfg - thunderbolt control channel
   */
  struct tb_ctl {
  	struct tb_nhi *nhi;
  	struct tb_ring *tx;
  	struct tb_ring *rx;
  
  	struct dma_pool *frame_pool;
  	struct ctl_pkg *rx_packets[TB_CTL_RX_PKG_COUNT];

  	struct mutex request_queue_lock;
  	struct list_head request_queue;
  	bool running;

  	event_cb callback;

  	void *callback_data;
  };
  
  
  #define tb_ctl_WARN(ctl, format, arg...) \
  	dev_WARN(&(ctl)->nhi->pdev->dev, format, ## arg)
  
  #define tb_ctl_err(ctl, format, arg...) \
  	dev_err(&(ctl)->nhi->pdev->dev, format, ## arg)
  
  #define tb_ctl_warn(ctl, format, arg...) \
  	dev_warn(&(ctl)->nhi->pdev->dev, format, ## arg)
  
  #define tb_ctl_info(ctl, format, arg...) \
  	dev_info(&(ctl)->nhi->pdev->dev, format, ## arg)

  #define tb_ctl_dbg(ctl, format, arg...) \
  	dev_dbg(&(ctl)->nhi->pdev->dev, format, ## arg)

  static DECLARE_WAIT_QUEUE_HEAD(tb_cfg_request_cancel_queue);
  /* Serializes access to request kref_get/put */
  static DEFINE_MUTEX(tb_cfg_request_lock);
  
  /**
   * tb_cfg_request_alloc() - Allocates a new config request
   *
   * This is refcounted object so when you are done with this, call
   * tb_cfg_request_put() to it.
   */
  struct tb_cfg_request *tb_cfg_request_alloc(void)
  {
  	struct tb_cfg_request *req;
  
  	req = kzalloc(sizeof(*req), GFP_KERNEL);
  	if (!req)
  		return NULL;
  
  	kref_init(&req->kref);
  
  	return req;
  }
  
  /**
   * tb_cfg_request_get() - Increase refcount of a request
   * @req: Request whose refcount is increased
   */
  void tb_cfg_request_get(struct tb_cfg_request *req)
  {
  	mutex_lock(&tb_cfg_request_lock);
  	kref_get(&req->kref);
  	mutex_unlock(&tb_cfg_request_lock);
  }
  
  static void tb_cfg_request_destroy(struct kref *kref)
  {
  	struct tb_cfg_request *req = container_of(kref, typeof(*req), kref);
  
  	kfree(req);
  }
  
  /**
   * tb_cfg_request_put() - Decrease refcount and possibly release the request
   * @req: Request whose refcount is decreased
   *
   * Call this function when you are done with the request. When refcount
   * goes to %0 the object is released.
   */
  void tb_cfg_request_put(struct tb_cfg_request *req)
  {
  	mutex_lock(&tb_cfg_request_lock);
  	kref_put(&req->kref, tb_cfg_request_destroy);
  	mutex_unlock(&tb_cfg_request_lock);
  }
  
  static int tb_cfg_request_enqueue(struct tb_ctl *ctl,
  				  struct tb_cfg_request *req)
  {
  	WARN_ON(test_bit(TB_CFG_REQUEST_ACTIVE, &req->flags));
  	WARN_ON(req->ctl);
  
  	mutex_lock(&ctl->request_queue_lock);
  	if (!ctl->running) {
  		mutex_unlock(&ctl->request_queue_lock);
  		return -ENOTCONN;
  	}
  	req->ctl = ctl;
  	list_add_tail(&req->list, &ctl->request_queue);
  	set_bit(TB_CFG_REQUEST_ACTIVE, &req->flags);
  	mutex_unlock(&ctl->request_queue_lock);
  	return 0;
  }
  
  static void tb_cfg_request_dequeue(struct tb_cfg_request *req)
  {
  	struct tb_ctl *ctl = req->ctl;
  
  	mutex_lock(&ctl->request_queue_lock);
  	list_del(&req->list);
  	clear_bit(TB_CFG_REQUEST_ACTIVE, &req->flags);
  	if (test_bit(TB_CFG_REQUEST_CANCELED, &req->flags))
  		wake_up(&tb_cfg_request_cancel_queue);
  	mutex_unlock(&ctl->request_queue_lock);
  }
  
  static bool tb_cfg_request_is_active(struct tb_cfg_request *req)
  {
  	return test_bit(TB_CFG_REQUEST_ACTIVE, &req->flags);
  }
  
  static struct tb_cfg_request *
  tb_cfg_request_find(struct tb_ctl *ctl, struct ctl_pkg *pkg)
  {
  	struct tb_cfg_request *req;
  	bool found = false;
  
  	mutex_lock(&pkg->ctl->request_queue_lock);
  	list_for_each_entry(req, &pkg->ctl->request_queue, list) {
  		tb_cfg_request_get(req);
  		if (req->match(req, pkg)) {
  			found = true;
  			break;
  		}
  		tb_cfg_request_put(req);
  	}
  	mutex_unlock(&pkg->ctl->request_queue_lock);
  
  	return found ? req : NULL;
  }

  /* utility functions */

  
  static int check_header(const struct ctl_pkg *pkg, u32 len,
  			enum tb_cfg_pkg_type type, u64 route)

  {
  	struct tb_cfg_header *header = pkg->buffer;
  
  	/* check frame, TODO: frame flags */
  	if (WARN(len != pkg->frame.size,
  			"wrong framesize (expected %#x, got %#x)
  ",
  			len, pkg->frame.size))
  		return -EIO;
  	if (WARN(type != pkg->frame.eof, "wrong eof (expected %#x, got %#x)
  ",
  			type, pkg->frame.eof))
  		return -EIO;
  	if (WARN(pkg->frame.sof, "wrong sof (expected 0x0, got %#x)
  ",
  			pkg->frame.sof))
  		return -EIO;
  
  	/* check header */
  	if (WARN(header->unknown != 1 << 9,
  			"header->unknown is %#x
  ", header->unknown))
  		return -EIO;

  	if (WARN(route != tb_cfg_get_route(header),

  			"wrong route (expected %llx, got %llx)",

  			route, tb_cfg_get_route(header)))

  		return -EIO;
  	return 0;
  }
  
  static int check_config_address(struct tb_cfg_address addr,
  				enum tb_cfg_space space, u32 offset,
  				u32 length)
  {
  	if (WARN(addr.zero, "addr.zero is %#x
  ", addr.zero))
  		return -EIO;
  	if (WARN(space != addr.space, "wrong space (expected %x, got %x
  )",
  			space, addr.space))
  		return -EIO;
  	if (WARN(offset != addr.offset, "wrong offset (expected %x, got %x
  )",
  			offset, addr.offset))
  		return -EIO;
  	if (WARN(length != addr.length, "wrong space (expected %x, got %x
  )",
  			length, addr.length))
  		return -EIO;

  	/*
  	 * We cannot check addr->port as it is set to the upstream port of the
  	 * sender.
  	 */
  	return 0;
  }

  static struct tb_cfg_result decode_error(const struct ctl_pkg *response)

  {
  	struct cfg_error_pkg *pkg = response->buffer;

  	struct tb_ctl *ctl = response->ctl;

  	struct tb_cfg_result res = { 0 };

  	res.response_route = tb_cfg_get_route(&pkg->header);

  	res.response_port = 0;
  	res.err = check_header(response, sizeof(*pkg), TB_CFG_PKG_ERROR,

  			       tb_cfg_get_route(&pkg->header));

  	if (res.err)
  		return res;

  	if (pkg->zero1)
  		tb_ctl_warn(ctl, "pkg->zero1 is %#x
  ", pkg->zero1);
  	if (pkg->zero2)
  		tb_ctl_warn(ctl, "pkg->zero2 is %#x
  ", pkg->zero2);
  	if (pkg->zero3)
  		tb_ctl_warn(ctl, "pkg->zero3 is %#x
  ", pkg->zero3);

  	res.err = 1;
  	res.tb_error = pkg->error;
  	res.response_port = pkg->port;
  	return res;
  
  }

  static struct tb_cfg_result parse_header(const struct ctl_pkg *pkg, u32 len,

  					 enum tb_cfg_pkg_type type, u64 route)
  {
  	struct tb_cfg_header *header = pkg->buffer;
  	struct tb_cfg_result res = { 0 };
  
  	if (pkg->frame.eof == TB_CFG_PKG_ERROR)
  		return decode_error(pkg);
  
  	res.response_port = 0; /* will be updated later for cfg_read/write */

  	res.response_route = tb_cfg_get_route(header);

  	res.err = check_header(pkg, len, type, route);
  	return res;
  }
  
  static void tb_cfg_print_error(struct tb_ctl *ctl,
  			       const struct tb_cfg_result *res)
  {
  	WARN_ON(res->err != 1);
  	switch (res->tb_error) {
  	case TB_CFG_ERROR_PORT_NOT_CONNECTED:
  		/* Port is not connected. This can happen during surprise
  		 * removal. Do not warn. */
  		return;
  	case TB_CFG_ERROR_INVALID_CONFIG_SPACE:
  		/*
  		 * Invalid cfg_space/offset/length combination in
  		 * cfg_read/cfg_write.
  		 */

  		tb_ctl_dbg(ctl, "%llx:%x: invalid config space or offset
  ",
  			   res->response_route, res->response_port);

  		return;
  	case TB_CFG_ERROR_NO_SUCH_PORT:
  		/*
  		 * - The route contains a non-existent port.
  		 * - The route contains a non-PHY port (e.g. PCIe).
  		 * - The port in cfg_read/cfg_write does not exist.
  		 */
  		tb_ctl_WARN(ctl, "CFG_ERROR(%llx:%x): Invalid port
  ",
  			res->response_route, res->response_port);
  		return;
  	case TB_CFG_ERROR_LOOP:
  		tb_ctl_WARN(ctl, "CFG_ERROR(%llx:%x): Route contains a loop
  ",
  			res->response_route, res->response_port);
  		return;

  	case TB_CFG_ERROR_LOCK:
  		tb_ctl_warn(ctl, "%llx:%x: downstream port is locked
  ",
  			    res->response_route, res->response_port);
  		return;

  	default:
  		/* 5,6,7,9 and 11 are also valid error codes */
  		tb_ctl_WARN(ctl, "CFG_ERROR(%llx:%x): Unknown error
  ",
  			res->response_route, res->response_port);
  		return;
  	}
  }

  static __be32 tb_crc(const void *data, size_t len)

  {
  	return cpu_to_be32(~__crc32c_le(~0, data, len));
  }
  
  static void tb_ctl_pkg_free(struct ctl_pkg *pkg)
  {
  	if (pkg) {
  		dma_pool_free(pkg->ctl->frame_pool,
  			      pkg->buffer, pkg->frame.buffer_phy);
  		kfree(pkg);
  	}
  }
  
  static struct ctl_pkg *tb_ctl_pkg_alloc(struct tb_ctl *ctl)
  {
  	struct ctl_pkg *pkg = kzalloc(sizeof(*pkg), GFP_KERNEL);
  	if (!pkg)

  		return NULL;

  	pkg->ctl = ctl;
  	pkg->buffer = dma_pool_alloc(ctl->frame_pool, GFP_KERNEL,
  				     &pkg->frame.buffer_phy);
  	if (!pkg->buffer) {
  		kfree(pkg);

  		return NULL;

  	}
  	return pkg;
  }
  
  
  /* RX/TX handling */
  
  static void tb_ctl_tx_callback(struct tb_ring *ring, struct ring_frame *frame,
  			       bool canceled)
  {
  	struct ctl_pkg *pkg = container_of(frame, typeof(*pkg), frame);
  	tb_ctl_pkg_free(pkg);
  }
  
  /**
   * tb_cfg_tx() - transmit a packet on the control channel
   *
   * len must be a multiple of four.
   *
   * Return: Returns 0 on success or an error code on failure.
   */

  static int tb_ctl_tx(struct tb_ctl *ctl, const void *data, size_t len,

  		     enum tb_cfg_pkg_type type)
  {
  	int res;
  	struct ctl_pkg *pkg;
  	if (len % 4 != 0) { /* required for le->be conversion */
  		tb_ctl_WARN(ctl, "TX: invalid size: %zu
  ", len);
  		return -EINVAL;
  	}
  	if (len > TB_FRAME_SIZE - 4) { /* checksum is 4 bytes */
  		tb_ctl_WARN(ctl, "TX: packet too large: %zu/%d
  ",
  			    len, TB_FRAME_SIZE - 4);
  		return -EINVAL;
  	}
  	pkg = tb_ctl_pkg_alloc(ctl);
  	if (!pkg)
  		return -ENOMEM;
  	pkg->frame.callback = tb_ctl_tx_callback;
  	pkg->frame.size = len + 4;
  	pkg->frame.sof = type;
  	pkg->frame.eof = type;
  	cpu_to_be32_array(pkg->buffer, data, len / 4);

  	*(__be32 *) (pkg->buffer + len) = tb_crc(pkg->buffer, len);

  	res = tb_ring_tx(ctl->tx, &pkg->frame);

  	if (res) /* ring is stopped */
  		tb_ctl_pkg_free(pkg);
  	return res;
  }
  
  /**

   * tb_ctl_handle_event() - acknowledge a plug event, invoke ctl->callback

   */

  static bool tb_ctl_handle_event(struct tb_ctl *ctl, enum tb_cfg_pkg_type type,

  				struct ctl_pkg *pkg, size_t size)

  {

  	return ctl->callback(ctl->callback_data, type, pkg->buffer, size);

  }
  
  static void tb_ctl_rx_submit(struct ctl_pkg *pkg)
  {

  	tb_ring_rx(pkg->ctl->rx, &pkg->frame); /*

  					     * We ignore failures during stop.
  					     * All rx packets are referenced
  					     * from ctl->rx_packets, so we do
  					     * not loose them.
  					     */
  }

  static int tb_async_error(const struct ctl_pkg *pkg)
  {
  	const struct cfg_error_pkg *error = (const struct cfg_error_pkg *)pkg;
  
  	if (pkg->frame.eof != TB_CFG_PKG_ERROR)
  		return false;
  
  	switch (error->error) {
  	case TB_CFG_ERROR_LINK_ERROR:
  	case TB_CFG_ERROR_HEC_ERROR_DETECTED:
  	case TB_CFG_ERROR_FLOW_CONTROL_ERROR:
  		return true;
  
  	default:
  		return false;
  	}
  }

  static void tb_ctl_rx_callback(struct tb_ring *ring, struct ring_frame *frame,
  			       bool canceled)
  {
  	struct ctl_pkg *pkg = container_of(frame, typeof(*pkg), frame);

  	struct tb_cfg_request *req;

  	__be32 crc32;

  
  	if (canceled)
  		return; /*
  			 * ring is stopped, packet is referenced from
  			 * ctl->rx_packets.
  			 */
  
  	if (frame->size < 4 || frame->size % 4 != 0) {
  		tb_ctl_err(pkg->ctl, "RX: invalid size %#x, dropping packet
  ",
  			   frame->size);
  		goto rx;
  	}
  
  	frame->size -= 4; /* remove checksum */

  	crc32 = tb_crc(pkg->buffer, frame->size);

  	be32_to_cpu_array(pkg->buffer, pkg->buffer, frame->size / 4);

  	switch (frame->eof) {
  	case TB_CFG_PKG_READ:
  	case TB_CFG_PKG_WRITE:
  	case TB_CFG_PKG_ERROR:
  	case TB_CFG_PKG_OVERRIDE:
  	case TB_CFG_PKG_RESET:
  		if (*(__be32 *)(pkg->buffer + frame->size) != crc32) {
  			tb_ctl_err(pkg->ctl,
  				   "RX: checksum mismatch, dropping packet
  ");
  			goto rx;
  		}
  		if (tb_async_error(pkg)) {
  			tb_ctl_handle_event(pkg->ctl, frame->eof,
  					    pkg, frame->size);
  			goto rx;
  		}
  		break;
  
  	case TB_CFG_PKG_EVENT:

  	case TB_CFG_PKG_XDOMAIN_RESP:
  	case TB_CFG_PKG_XDOMAIN_REQ:

  		if (*(__be32 *)(pkg->buffer + frame->size) != crc32) {
  			tb_ctl_err(pkg->ctl,
  				   "RX: checksum mismatch, dropping packet
  ");
  			goto rx;
  		}

  		fallthrough;

  	case TB_CFG_PKG_ICM_EVENT:

  		if (tb_ctl_handle_event(pkg->ctl, frame->eof, pkg, frame->size))
  			goto rx;
  		break;

  
  	default:

  		break;

  	}

  	/*
  	 * The received packet will be processed only if there is an
  	 * active request and that the packet is what is expected. This
  	 * prevents packets such as replies coming after timeout has
  	 * triggered from messing with the active requests.
  	 */
  	req = tb_cfg_request_find(pkg->ctl, pkg);
  	if (req) {
  		if (req->copy(req, pkg))
  			schedule_work(&req->work);
  		tb_cfg_request_put(req);

  	}

  rx:
  	tb_ctl_rx_submit(pkg);
  }

  static void tb_cfg_request_work(struct work_struct *work)
  {
  	struct tb_cfg_request *req = container_of(work, typeof(*req), work);
  
  	if (!test_bit(TB_CFG_REQUEST_CANCELED, &req->flags))
  		req->callback(req->callback_data);
  
  	tb_cfg_request_dequeue(req);
  	tb_cfg_request_put(req);
  }

  /**

   * tb_cfg_request() - Start control request not waiting for it to complete
   * @ctl: Control channel to use
   * @req: Request to start
   * @callback: Callback called when the request is completed
   * @callback_data: Data to be passed to @callback
   *
   * This queues @req on the given control channel without waiting for it
   * to complete. When the request completes @callback is called.

   */

  int tb_cfg_request(struct tb_ctl *ctl, struct tb_cfg_request *req,
  		   void (*callback)(void *), void *callback_data)

  {

  	int ret;

  	req->flags = 0;
  	req->callback = callback;
  	req->callback_data = callback_data;
  	INIT_WORK(&req->work, tb_cfg_request_work);
  	INIT_LIST_HEAD(&req->list);

  	tb_cfg_request_get(req);
  	ret = tb_cfg_request_enqueue(ctl, req);
  	if (ret)
  		goto err_put;
  
  	ret = tb_ctl_tx(ctl, req->request, req->request_size,
  			req->request_type);
  	if (ret)
  		goto err_dequeue;
  
  	if (!req->response)
  		schedule_work(&req->work);
  
  	return 0;
  
  err_dequeue:
  	tb_cfg_request_dequeue(req);
  err_put:
  	tb_cfg_request_put(req);
  
  	return ret;
  }
  
  /**
   * tb_cfg_request_cancel() - Cancel a control request
   * @req: Request to cancel
   * @err: Error to assign to the request
   *
   * This function can be used to cancel ongoing request. It will wait
   * until the request is not active anymore.
   */
  void tb_cfg_request_cancel(struct tb_cfg_request *req, int err)
  {
  	set_bit(TB_CFG_REQUEST_CANCELED, &req->flags);
  	schedule_work(&req->work);
  	wait_event(tb_cfg_request_cancel_queue, !tb_cfg_request_is_active(req));
  	req->result.err = err;

  }

  static void tb_cfg_request_complete(void *data)
  {
  	complete(data);
  }
  
  /**
   * tb_cfg_request_sync() - Start control request and wait until it completes
   * @ctl: Control channel to use
   * @req: Request to start
   * @timeout_msec: Timeout how long to wait @req to complete
   *
   * Starts a control request and waits until it completes. If timeout
   * triggers the request is canceled before function returns. Note the
   * caller needs to make sure only one message for given switch is active
   * at a time.
   */
  struct tb_cfg_result tb_cfg_request_sync(struct tb_ctl *ctl,
  					 struct tb_cfg_request *req,
  					 int timeout_msec)
  {
  	unsigned long timeout = msecs_to_jiffies(timeout_msec);
  	struct tb_cfg_result res = { 0 };
  	DECLARE_COMPLETION_ONSTACK(done);
  	int ret;
  
  	ret = tb_cfg_request(ctl, req, tb_cfg_request_complete, &done);
  	if (ret) {
  		res.err = ret;
  		return res;
  	}
  
  	if (!wait_for_completion_timeout(&done, timeout))
  		tb_cfg_request_cancel(req, -ETIMEDOUT);
  
  	flush_work(&req->work);
  
  	return req->result;
  }

  
  /* public interface, alloc/start/stop/free */
  
  /**
   * tb_ctl_alloc() - allocate a control channel
   *
   * cb will be invoked once for every hot plug event.
   *
   * Return: Returns a pointer on success or NULL on failure.
   */

  struct tb_ctl *tb_ctl_alloc(struct tb_nhi *nhi, event_cb cb, void *cb_data)

  {
  	int i;
  	struct tb_ctl *ctl = kzalloc(sizeof(*ctl), GFP_KERNEL);
  	if (!ctl)
  		return NULL;
  	ctl->nhi = nhi;
  	ctl->callback = cb;
  	ctl->callback_data = cb_data;

  	mutex_init(&ctl->request_queue_lock);
  	INIT_LIST_HEAD(&ctl->request_queue);

  	ctl->frame_pool = dma_pool_create("thunderbolt_ctl", &nhi->pdev->dev,
  					 TB_FRAME_SIZE, 4, 0);
  	if (!ctl->frame_pool)
  		goto err;

  	ctl->tx = tb_ring_alloc_tx(nhi, 0, 10, RING_FLAG_NO_SUSPEND);

  	if (!ctl->tx)
  		goto err;

  	ctl->rx = tb_ring_alloc_rx(nhi, 0, 10, RING_FLAG_NO_SUSPEND, 0xffff,

  				0xffff, NULL, NULL);

  	if (!ctl->rx)
  		goto err;
  
  	for (i = 0; i < TB_CTL_RX_PKG_COUNT; i++) {
  		ctl->rx_packets[i] = tb_ctl_pkg_alloc(ctl);
  		if (!ctl->rx_packets[i])
  			goto err;
  		ctl->rx_packets[i]->frame.callback = tb_ctl_rx_callback;
  	}

  	tb_ctl_dbg(ctl, "control channel created
  ");

  	return ctl;
  err:
  	tb_ctl_free(ctl);
  	return NULL;
  }
  
  /**
   * tb_ctl_free() - free a control channel
   *
   * Must be called after tb_ctl_stop.
   *
   * Must NOT be called from ctl->callback.
   */
  void tb_ctl_free(struct tb_ctl *ctl)
  {
  	int i;

  
  	if (!ctl)
  		return;

  	if (ctl->rx)

  		tb_ring_free(ctl->rx);

  	if (ctl->tx)

  		tb_ring_free(ctl->tx);

  
  	/* free RX packets */
  	for (i = 0; i < TB_CTL_RX_PKG_COUNT; i++)
  		tb_ctl_pkg_free(ctl->rx_packets[i]);

  	dma_pool_destroy(ctl->frame_pool);

  	kfree(ctl);
  }
  
  /**
   * tb_cfg_start() - start/resume the control channel
   */
  void tb_ctl_start(struct tb_ctl *ctl)
  {
  	int i;

  	tb_ctl_dbg(ctl, "control channel starting...
  ");

  	tb_ring_start(ctl->tx); /* is used to ack hotplug packets, start first */
  	tb_ring_start(ctl->rx);

  	for (i = 0; i < TB_CTL_RX_PKG_COUNT; i++)
  		tb_ctl_rx_submit(ctl->rx_packets[i]);

  
  	ctl->running = true;

  }
  
  /**
   * control() - pause the control channel
   *
   * All invocations of ctl->callback will have finished after this method
   * returns.
   *
   * Must NOT be called from ctl->callback.
   */
  void tb_ctl_stop(struct tb_ctl *ctl)
  {

  	mutex_lock(&ctl->request_queue_lock);
  	ctl->running = false;
  	mutex_unlock(&ctl->request_queue_lock);

  	tb_ring_stop(ctl->rx);
  	tb_ring_stop(ctl->tx);

  	if (!list_empty(&ctl->request_queue))
  		tb_ctl_WARN(ctl, "dangling request in request_queue
  ");
  	INIT_LIST_HEAD(&ctl->request_queue);

  	tb_ctl_dbg(ctl, "control channel stopped
  ");

  }
  
  /* public interface, commands */
  
  /**

   * tb_cfg_ack_plug() - Ack hot plug/unplug event
   * @ctl: Control channel to use
   * @route: Router that originated the event
   * @port: Port where the hot plug/unplug happened
   * @unplug: Ack hot plug or unplug

   *

   * Call this as response for hot plug/unplug event to ack it.
   * Returns %0 on success or an error code on failure.

   */

  int tb_cfg_ack_plug(struct tb_ctl *ctl, u64 route, u32 port, bool unplug)

  {
  	struct cfg_error_pkg pkg = {

  		.header = tb_cfg_make_header(route),

  		.port = port,

  		.error = TB_CFG_ERROR_ACK_PLUG_EVENT,
  		.pg = unplug ? TB_CFG_ERROR_PG_HOT_UNPLUG
  			     : TB_CFG_ERROR_PG_HOT_PLUG,

  	};

  	tb_ctl_dbg(ctl, "acking hot %splug event on %llx:%x
  ",
  		   unplug ? "un" : "", route, port);

  	return tb_ctl_tx(ctl, &pkg, sizeof(pkg), TB_CFG_PKG_ERROR);
  }

  static bool tb_cfg_match(const struct tb_cfg_request *req,
  			 const struct ctl_pkg *pkg)
  {
  	u64 route = tb_cfg_get_route(pkg->buffer) & ~BIT_ULL(63);
  
  	if (pkg->frame.eof == TB_CFG_PKG_ERROR)
  		return true;
  
  	if (pkg->frame.eof != req->response_type)
  		return false;
  	if (route != tb_cfg_get_route(req->request))
  		return false;
  	if (pkg->frame.size != req->response_size)
  		return false;
  
  	if (pkg->frame.eof == TB_CFG_PKG_READ ||
  	    pkg->frame.eof == TB_CFG_PKG_WRITE) {
  		const struct cfg_read_pkg *req_hdr = req->request;
  		const struct cfg_read_pkg *res_hdr = pkg->buffer;
  
  		if (req_hdr->addr.seq != res_hdr->addr.seq)
  			return false;
  	}
  
  	return true;
  }
  
  static bool tb_cfg_copy(struct tb_cfg_request *req, const struct ctl_pkg *pkg)
  {
  	struct tb_cfg_result res;
  
  	/* Now make sure it is in expected format */
  	res = parse_header(pkg, req->response_size, req->response_type,
  			   tb_cfg_get_route(req->request));
  	if (!res.err)
  		memcpy(req->response, pkg->buffer, req->response_size);
  
  	req->result = res;
  
  	/* Always complete when first response is received */
  	return true;
  }

  /**
   * tb_cfg_reset() - send a reset packet and wait for a response
   *
   * If the switch at route is incorrectly configured then we will not receive a
   * reply (even though the switch will reset). The caller should check for
   * -ETIMEDOUT and attempt to reconfigure the switch.
   */
  struct tb_cfg_result tb_cfg_reset(struct tb_ctl *ctl, u64 route,
  				  int timeout_msec)
  {

  	struct cfg_reset_pkg request = { .header = tb_cfg_make_header(route) };

  	struct tb_cfg_result res = { 0 };

  	struct tb_cfg_header reply;

  	struct tb_cfg_request *req;
  
  	req = tb_cfg_request_alloc();
  	if (!req) {
  		res.err = -ENOMEM;
  		return res;
  	}
  
  	req->match = tb_cfg_match;
  	req->copy = tb_cfg_copy;
  	req->request = &request;
  	req->request_size = sizeof(request);
  	req->request_type = TB_CFG_PKG_RESET;
  	req->response = &reply;
  	req->response_size = sizeof(reply);

  	req->response_type = TB_CFG_PKG_RESET;

  
  	res = tb_cfg_request_sync(ctl, req, timeout_msec);

  	tb_cfg_request_put(req);

  	return res;

  }
  
  /**
   * tb_cfg_read() - read from config space into buffer
   *
   * Offset and length are in dwords.
   */
  struct tb_cfg_result tb_cfg_read_raw(struct tb_ctl *ctl, void *buffer,
  		u64 route, u32 port, enum tb_cfg_space space,
  		u32 offset, u32 length, int timeout_msec)
  {
  	struct tb_cfg_result res = { 0 };
  	struct cfg_read_pkg request = {

  		.header = tb_cfg_make_header(route),

  		.addr = {
  			.port = port,
  			.space = space,
  			.offset = offset,
  			.length = length,
  		},
  	};
  	struct cfg_write_pkg reply;

  	int retries = 0;

  	while (retries < TB_CTL_RETRIES) {
  		struct tb_cfg_request *req;
  
  		req = tb_cfg_request_alloc();
  		if (!req) {
  			res.err = -ENOMEM;
  			return res;
  		}
  
  		request.addr.seq = retries++;
  
  		req->match = tb_cfg_match;
  		req->copy = tb_cfg_copy;
  		req->request = &request;
  		req->request_size = sizeof(request);
  		req->request_type = TB_CFG_PKG_READ;
  		req->response = &reply;
  		req->response_size = 12 + 4 * length;
  		req->response_type = TB_CFG_PKG_READ;
  
  		res = tb_cfg_request_sync(ctl, req, timeout_msec);
  
  		tb_cfg_request_put(req);
  
  		if (res.err != -ETIMEDOUT)
  			break;
  
  		/* Wait a bit (arbitrary time) until we send a retry */
  		usleep_range(10, 100);
  	}

  	if (res.err)
  		return res;
  
  	res.response_port = reply.addr.port;
  	res.err = check_config_address(reply.addr, space, offset, length);
  	if (!res.err)
  		memcpy(buffer, &reply.data, 4 * length);
  	return res;
  }
  
  /**
   * tb_cfg_write() - write from buffer into config space
   *
   * Offset and length are in dwords.
   */

  struct tb_cfg_result tb_cfg_write_raw(struct tb_ctl *ctl, const void *buffer,

  		u64 route, u32 port, enum tb_cfg_space space,
  		u32 offset, u32 length, int timeout_msec)
  {
  	struct tb_cfg_result res = { 0 };
  	struct cfg_write_pkg request = {

  		.header = tb_cfg_make_header(route),

  		.addr = {
  			.port = port,
  			.space = space,
  			.offset = offset,
  			.length = length,
  		},
  	};
  	struct cfg_read_pkg reply;

  	int retries = 0;

  
  	memcpy(&request.data, buffer, length * 4);

  	while (retries < TB_CTL_RETRIES) {
  		struct tb_cfg_request *req;
  
  		req = tb_cfg_request_alloc();
  		if (!req) {
  			res.err = -ENOMEM;
  			return res;
  		}
  
  		request.addr.seq = retries++;
  
  		req->match = tb_cfg_match;
  		req->copy = tb_cfg_copy;
  		req->request = &request;
  		req->request_size = 12 + 4 * length;
  		req->request_type = TB_CFG_PKG_WRITE;
  		req->response = &reply;
  		req->response_size = sizeof(reply);
  		req->response_type = TB_CFG_PKG_WRITE;
  
  		res = tb_cfg_request_sync(ctl, req, timeout_msec);
  
  		tb_cfg_request_put(req);
  
  		if (res.err != -ETIMEDOUT)
  			break;
  
  		/* Wait a bit (arbitrary time) until we send a retry */
  		usleep_range(10, 100);
  	}

  	if (res.err)
  		return res;
  
  	res.response_port = reply.addr.port;
  	res.err = check_config_address(reply.addr, space, offset, length);
  	return res;
  }

  static int tb_cfg_get_error(struct tb_ctl *ctl, enum tb_cfg_space space,
  			    const struct tb_cfg_result *res)
  {
  	/*
  	 * For unimplemented ports access to port config space may return
  	 * TB_CFG_ERROR_INVALID_CONFIG_SPACE (alternatively their type is
  	 * set to TB_TYPE_INACTIVE). In the former case return -ENODEV so
  	 * that the caller can mark the port as disabled.
  	 */
  	if (space == TB_CFG_PORT &&
  	    res->tb_error == TB_CFG_ERROR_INVALID_CONFIG_SPACE)
  		return -ENODEV;
  
  	tb_cfg_print_error(ctl, res);

  
  	if (res->tb_error == TB_CFG_ERROR_LOCK)
  		return -EACCES;

  	return -EIO;
  }

  int tb_cfg_read(struct tb_ctl *ctl, void *buffer, u64 route, u32 port,
  		enum tb_cfg_space space, u32 offset, u32 length)
  {
  	struct tb_cfg_result res = tb_cfg_read_raw(ctl, buffer, route, port,
  			space, offset, length, TB_CFG_DEFAULT_TIMEOUT);

  	switch (res.err) {
  	case 0:
  		/* Success */
  		break;
  
  	case 1:
  		/* Thunderbolt error, tb_error holds the actual number */

  		return tb_cfg_get_error(ctl, space, &res);

  
  	case -ETIMEDOUT:

  		tb_ctl_warn(ctl, "%llx: timeout reading config space %u from %#x
  ",
  			    route, space, offset);

  		break;
  
  	default:
  		WARN(1, "tb_cfg_read: %d
  ", res.err);
  		break;

  	}

  	return res.err;
  }

  int tb_cfg_write(struct tb_ctl *ctl, const void *buffer, u64 route, u32 port,

  		 enum tb_cfg_space space, u32 offset, u32 length)
  {
  	struct tb_cfg_result res = tb_cfg_write_raw(ctl, buffer, route, port,
  			space, offset, length, TB_CFG_DEFAULT_TIMEOUT);

  	switch (res.err) {
  	case 0:
  		/* Success */
  		break;
  
  	case 1:
  		/* Thunderbolt error, tb_error holds the actual number */

  		return tb_cfg_get_error(ctl, space, &res);

  
  	case -ETIMEDOUT:

  		tb_ctl_warn(ctl, "%llx: timeout writing config space %u to %#x
  ",
  			    route, space, offset);

  		break;
  
  	default:
  		WARN(1, "tb_cfg_write: %d
  ", res.err);
  		break;

  	}

  	return res.err;
  }
  
  /**
   * tb_cfg_get_upstream_port() - get upstream port number of switch at route
   *
   * Reads the first dword from the switches TB_CFG_SWITCH config area and
   * returns the port number from which the reply originated.
   *
   * Return: Returns the upstream port number on success or an error code on
   * failure.
   */
  int tb_cfg_get_upstream_port(struct tb_ctl *ctl, u64 route)
  {
  	u32 dummy;
  	struct tb_cfg_result res = tb_cfg_read_raw(ctl, &dummy, route, 0,
  						   TB_CFG_SWITCH, 0, 1,
  						   TB_CFG_DEFAULT_TIMEOUT);
  	if (res.err == 1)
  		return -EIO;
  	if (res.err)
  		return res.err;
  	return res.response_port;
  }