ntb_transport.c 43.7 KB
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/*
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 *   redistributing this file, you may do so under either license.
 *
 *   GPL LICENSE SUMMARY
 *
 *   Copyright(c) 2012 Intel Corporation. All rights reserved.
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of version 2 of the GNU General Public License as
 *   published by the Free Software Foundation.
 *
 *   BSD LICENSE
 *
 *   Copyright(c) 2012 Intel Corporation. All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copy
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Intel PCIe NTB Linux driver
 *
 * Contact Information:
 * Jon Mason <jon.mason@intel.com>
 */
#include <linux/debugfs.h>
#include <linux/delay.h>
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#include <linux/dmaengine.h>
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#include <linux/dma-mapping.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/ntb.h>
#include "ntb_hw.h"

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#define NTB_TRANSPORT_VERSION	3
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static unsigned int transport_mtu = 0x401E;
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module_param(transport_mtu, uint, 0644);
MODULE_PARM_DESC(transport_mtu, "Maximum size of NTB transport packets");

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static unsigned char max_num_clients;
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module_param(max_num_clients, byte, 0644);
MODULE_PARM_DESC(max_num_clients, "Maximum number of NTB transport clients");

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static unsigned int copy_bytes = 1024;
module_param(copy_bytes, uint, 0644);
MODULE_PARM_DESC(copy_bytes, "Threshold under which NTB will use the CPU to copy instead of DMA");

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struct ntb_queue_entry {
	/* ntb_queue list reference */
	struct list_head entry;
	/* pointers to data to be transfered */
	void *cb_data;
	void *buf;
	unsigned int len;
	unsigned int flags;
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	struct ntb_transport_qp *qp;
	union {
		struct ntb_payload_header __iomem *tx_hdr;
		struct ntb_payload_header *rx_hdr;
	};
	unsigned int index;
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};

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struct ntb_rx_info {
	unsigned int entry;
};

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struct ntb_transport_qp {
	struct ntb_transport *transport;
	struct ntb_device *ndev;
	void *cb_data;
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	struct dma_chan *dma_chan;
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	bool client_ready;
	bool qp_link;
	u8 qp_num;	/* Only 64 QP's are allowed.  0-63 */

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	struct ntb_rx_info __iomem *rx_info;
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	struct ntb_rx_info *remote_rx_info;

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	void (*tx_handler) (struct ntb_transport_qp *qp, void *qp_data,
			    void *data, int len);
	struct list_head tx_free_q;
	spinlock_t ntb_tx_free_q_lock;
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	void __iomem *tx_mw;
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	dma_addr_t tx_mw_phys;
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	unsigned int tx_index;
	unsigned int tx_max_entry;
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	unsigned int tx_max_frame;
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	void (*rx_handler) (struct ntb_transport_qp *qp, void *qp_data,
			    void *data, int len);
	struct tasklet_struct rx_work;
	struct list_head rx_pend_q;
	struct list_head rx_free_q;
	spinlock_t ntb_rx_pend_q_lock;
	spinlock_t ntb_rx_free_q_lock;
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	void *rx_buff;
	unsigned int rx_index;
	unsigned int rx_max_entry;
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	unsigned int rx_max_frame;
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	dma_cookie_t last_cookie;
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	void (*event_handler) (void *data, int status);
	struct delayed_work link_work;
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	struct work_struct link_cleanup;
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	struct dentry *debugfs_dir;
	struct dentry *debugfs_stats;

	/* Stats */
	u64 rx_bytes;
	u64 rx_pkts;
	u64 rx_ring_empty;
	u64 rx_err_no_buf;
	u64 rx_err_oflow;
	u64 rx_err_ver;
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	u64 rx_memcpy;
	u64 rx_async;
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	u64 tx_bytes;
	u64 tx_pkts;
	u64 tx_ring_full;
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	u64 tx_err_no_buf;
	u64 tx_memcpy;
	u64 tx_async;
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};

struct ntb_transport_mw {
	size_t size;
	void *virt_addr;
	dma_addr_t dma_addr;
};

struct ntb_transport_client_dev {
	struct list_head entry;
	struct device dev;
};

struct ntb_transport {
	struct list_head entry;
	struct list_head client_devs;

	struct ntb_device *ndev;
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	struct ntb_transport_mw *mw;
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	struct ntb_transport_qp *qps;
	unsigned int max_qps;
	unsigned long qp_bitmap;
	bool transport_link;
	struct delayed_work link_work;
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	struct work_struct link_cleanup;
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};

enum {
	DESC_DONE_FLAG = 1 << 0,
	LINK_DOWN_FLAG = 1 << 1,
};

struct ntb_payload_header {
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	unsigned int ver;
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	unsigned int len;
	unsigned int flags;
};

enum {
	VERSION = 0,
	QP_LINKS,
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	NUM_QPS,
	NUM_MWS,
	MW0_SZ_HIGH,
	MW0_SZ_LOW,
	MW1_SZ_HIGH,
	MW1_SZ_LOW,
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	MAX_SPAD,
};

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#define QP_TO_MW(ndev, qp)	((qp) % ntb_max_mw(ndev))
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#define NTB_QP_DEF_NUM_ENTRIES	100
#define NTB_LINK_DOWN_TIMEOUT	10

static int ntb_match_bus(struct device *dev, struct device_driver *drv)
{
	return !strncmp(dev_name(dev), drv->name, strlen(drv->name));
}

static int ntb_client_probe(struct device *dev)
{
	const struct ntb_client *drv = container_of(dev->driver,
						    struct ntb_client, driver);
	struct pci_dev *pdev = container_of(dev->parent, struct pci_dev, dev);
	int rc = -EINVAL;

	get_device(dev);
	if (drv && drv->probe)
		rc = drv->probe(pdev);
	if (rc)
		put_device(dev);

	return rc;
}

static int ntb_client_remove(struct device *dev)
{
	const struct ntb_client *drv = container_of(dev->driver,
						    struct ntb_client, driver);
	struct pci_dev *pdev = container_of(dev->parent, struct pci_dev, dev);

	if (drv && drv->remove)
		drv->remove(pdev);

	put_device(dev);

	return 0;
}

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static struct bus_type ntb_bus_type = {
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	.name = "ntb_bus",
	.match = ntb_match_bus,
	.probe = ntb_client_probe,
	.remove = ntb_client_remove,
};

static LIST_HEAD(ntb_transport_list);

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static int ntb_bus_init(struct ntb_transport *nt)
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{
	if (list_empty(&ntb_transport_list)) {
		int rc = bus_register(&ntb_bus_type);
		if (rc)
			return rc;
	}

	list_add(&nt->entry, &ntb_transport_list);

	return 0;
}

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static void ntb_bus_remove(struct ntb_transport *nt)
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{
	struct ntb_transport_client_dev *client_dev, *cd;

	list_for_each_entry_safe(client_dev, cd, &nt->client_devs, entry) {
		dev_err(client_dev->dev.parent, "%s still attached to bus, removing\n",
			dev_name(&client_dev->dev));
		list_del(&client_dev->entry);
		device_unregister(&client_dev->dev);
	}

	list_del(&nt->entry);

	if (list_empty(&ntb_transport_list))
		bus_unregister(&ntb_bus_type);
}

static void ntb_client_release(struct device *dev)
{
	struct ntb_transport_client_dev *client_dev;
	client_dev = container_of(dev, struct ntb_transport_client_dev, dev);

	kfree(client_dev);
}

/**
 * ntb_unregister_client_dev - Unregister NTB client device
 * @device_name: Name of NTB client device
 *
 * Unregister an NTB client device with the NTB transport layer
 */
void ntb_unregister_client_dev(char *device_name)
{
	struct ntb_transport_client_dev *client, *cd;
	struct ntb_transport *nt;

	list_for_each_entry(nt, &ntb_transport_list, entry)
		list_for_each_entry_safe(client, cd, &nt->client_devs, entry)
			if (!strncmp(dev_name(&client->dev), device_name,
				     strlen(device_name))) {
				list_del(&client->entry);
				device_unregister(&client->dev);
			}
}
EXPORT_SYMBOL_GPL(ntb_unregister_client_dev);

/**
 * ntb_register_client_dev - Register NTB client device
 * @device_name: Name of NTB client device
 *
 * Register an NTB client device with the NTB transport layer
 */
int ntb_register_client_dev(char *device_name)
{
	struct ntb_transport_client_dev *client_dev;
	struct ntb_transport *nt;
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	int rc, i = 0;
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	if (list_empty(&ntb_transport_list))
		return -ENODEV;

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	list_for_each_entry(nt, &ntb_transport_list, entry) {
		struct device *dev;

		client_dev = kzalloc(sizeof(struct ntb_transport_client_dev),
				     GFP_KERNEL);
		if (!client_dev) {
			rc = -ENOMEM;
			goto err;
		}

		dev = &client_dev->dev;

		/* setup and register client devices */
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		dev_set_name(dev, "%s%d", device_name, i);
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		dev->bus = &ntb_bus_type;
		dev->release = ntb_client_release;
		dev->parent = &ntb_query_pdev(nt->ndev)->dev;

		rc = device_register(dev);
		if (rc) {
			kfree(client_dev);
			goto err;
		}

		list_add_tail(&client_dev->entry, &nt->client_devs);
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		i++;
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	}

	return 0;

err:
	ntb_unregister_client_dev(device_name);

	return rc;
}
EXPORT_SYMBOL_GPL(ntb_register_client_dev);

/**
 * ntb_register_client - Register NTB client driver
 * @drv: NTB client driver to be registered
 *
 * Register an NTB client driver with the NTB transport layer
 *
 * RETURNS: An appropriate -ERRNO error value on error, or zero for success.
 */
int ntb_register_client(struct ntb_client *drv)
{
	drv->driver.bus = &ntb_bus_type;

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	if (list_empty(&ntb_transport_list))
		return -ENODEV;

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	return driver_register(&drv->driver);
}
EXPORT_SYMBOL_GPL(ntb_register_client);

/**
 * ntb_unregister_client - Unregister NTB client driver
 * @drv: NTB client driver to be unregistered
 *
 * Unregister an NTB client driver with the NTB transport layer
 *
 * RETURNS: An appropriate -ERRNO error value on error, or zero for success.
 */
void ntb_unregister_client(struct ntb_client *drv)
{
	driver_unregister(&drv->driver);
}
EXPORT_SYMBOL_GPL(ntb_unregister_client);

static ssize_t debugfs_read(struct file *filp, char __user *ubuf, size_t count,
			    loff_t *offp)
{
	struct ntb_transport_qp *qp;
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	char *buf;
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	ssize_t ret, out_offset, out_count;

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	out_count = 1000;
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	buf = kmalloc(out_count, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;
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	qp = filp->private_data;
	out_offset = 0;
	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "NTB QP stats\n");
	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "rx_bytes - \t%llu\n", qp->rx_bytes);
	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "rx_pkts - \t%llu\n", qp->rx_pkts);
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	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "rx_memcpy - \t%llu\n", qp->rx_memcpy);
	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "rx_async - \t%llu\n", qp->rx_async);
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	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "rx_ring_empty - %llu\n", qp->rx_ring_empty);
	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "rx_err_no_buf - %llu\n", qp->rx_err_no_buf);
	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "rx_err_oflow - \t%llu\n", qp->rx_err_oflow);
	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "rx_err_ver - \t%llu\n", qp->rx_err_ver);
	out_offset += snprintf(buf + out_offset, out_count - out_offset,
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			       "rx_buff - \t%p\n", qp->rx_buff);
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	out_offset += snprintf(buf + out_offset, out_count - out_offset,
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			       "rx_index - \t%u\n", qp->rx_index);
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	out_offset += snprintf(buf + out_offset, out_count - out_offset,
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			       "rx_max_entry - \t%u\n", qp->rx_max_entry);
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	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "tx_bytes - \t%llu\n", qp->tx_bytes);
	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "tx_pkts - \t%llu\n", qp->tx_pkts);
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	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "tx_memcpy - \t%llu\n", qp->tx_memcpy);
	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "tx_async - \t%llu\n", qp->tx_async);
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	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "tx_ring_full - \t%llu\n", qp->tx_ring_full);
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	out_offset += snprintf(buf + out_offset, out_count - out_offset,
			       "tx_err_no_buf - %llu\n", qp->tx_err_no_buf);
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	out_offset += snprintf(buf + out_offset, out_count - out_offset,
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			       "tx_mw - \t%p\n", qp->tx_mw);
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	out_offset += snprintf(buf + out_offset, out_count - out_offset,
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			       "tx_index - \t%u\n", qp->tx_index);
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	out_offset += snprintf(buf + out_offset, out_count - out_offset,
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			       "tx_max_entry - \t%u\n", qp->tx_max_entry);
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	out_offset += snprintf(buf + out_offset, out_count - out_offset,
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			       "\nQP Link %s\n", (qp->qp_link == NTB_LINK_UP) ?
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			       "Up" : "Down");
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	if (out_offset > out_count)
		out_offset = out_count;
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	ret = simple_read_from_buffer(ubuf, count, offp, buf, out_offset);
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	kfree(buf);
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	return ret;
}

static const struct file_operations ntb_qp_debugfs_stats = {
	.owner = THIS_MODULE,
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	.open = simple_open,
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	.read = debugfs_read,
};

static void ntb_list_add(spinlock_t *lock, struct list_head *entry,
			 struct list_head *list)
{
	unsigned long flags;

	spin_lock_irqsave(lock, flags);
	list_add_tail(entry, list);
	spin_unlock_irqrestore(lock, flags);
}

static struct ntb_queue_entry *ntb_list_rm(spinlock_t *lock,
						struct list_head *list)
{
	struct ntb_queue_entry *entry;
	unsigned long flags;

	spin_lock_irqsave(lock, flags);
	if (list_empty(list)) {
		entry = NULL;
		goto out;
	}
	entry = list_first_entry(list, struct ntb_queue_entry, entry);
	list_del(&entry->entry);
out:
	spin_unlock_irqrestore(lock, flags);

	return entry;
}

static void ntb_transport_setup_qp_mw(struct ntb_transport *nt,
				      unsigned int qp_num)
{
	struct ntb_transport_qp *qp = &nt->qps[qp_num];
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	unsigned int rx_size, num_qps_mw;
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	u8 mw_num, mw_max;
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	unsigned int i;
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	mw_max = ntb_max_mw(nt->ndev);
	mw_num = QP_TO_MW(nt->ndev, qp_num);

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	WARN_ON(nt->mw[mw_num].virt_addr == NULL);
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	if (nt->max_qps % mw_max && mw_num < nt->max_qps % mw_max)
		num_qps_mw = nt->max_qps / mw_max + 1;
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	else
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		num_qps_mw = nt->max_qps / mw_max;
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	rx_size = (unsigned int) nt->mw[mw_num].size / num_qps_mw;
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	qp->rx_buff = nt->mw[mw_num].virt_addr + qp_num / mw_max * rx_size;
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	rx_size -= sizeof(struct ntb_rx_info);

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	qp->remote_rx_info = qp->rx_buff + rx_size;

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	/* Due to housekeeping, there must be atleast 2 buffs */
	qp->rx_max_frame = min(transport_mtu, rx_size / 2);
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	qp->rx_max_entry = rx_size / qp->rx_max_frame;
	qp->rx_index = 0;

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	qp->remote_rx_info->entry = qp->rx_max_entry - 1;
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	/* setup the hdr offsets with 0's */
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	for (i = 0; i < qp->rx_max_entry; i++) {
		void *offset = qp->rx_buff + qp->rx_max_frame * (i + 1) -
			       sizeof(struct ntb_payload_header);
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		memset(offset, 0, sizeof(struct ntb_payload_header));
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	}
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	qp->rx_pkts = 0;
	qp->tx_pkts = 0;
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	qp->tx_index = 0;
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}

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static void ntb_free_mw(struct ntb_transport *nt, int num_mw)
{
	struct ntb_transport_mw *mw = &nt->mw[num_mw];
	struct pci_dev *pdev = ntb_query_pdev(nt->ndev);

	if (!mw->virt_addr)
		return;

	dma_free_coherent(&pdev->dev, mw->size, mw->virt_addr, mw->dma_addr);
	mw->virt_addr = NULL;
}

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static int ntb_set_mw(struct ntb_transport *nt, int num_mw, unsigned int size)
{
	struct ntb_transport_mw *mw = &nt->mw[num_mw];
	struct pci_dev *pdev = ntb_query_pdev(nt->ndev);

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	/* No need to re-setup */
	if (mw->size == ALIGN(size, 4096))
		return 0;

	if (mw->size != 0)
		ntb_free_mw(nt, num_mw);

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	/* Alloc memory for receiving data.  Must be 4k aligned */
	mw->size = ALIGN(size, 4096);

	mw->virt_addr = dma_alloc_coherent(&pdev->dev, mw->size, &mw->dma_addr,
					   GFP_KERNEL);
	if (!mw->virt_addr) {
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		mw->size = 0;
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		dev_err(&pdev->dev, "Unable to allocate MW buffer of size %d\n",
		       (int) mw->size);
		return -ENOMEM;
	}

	/* Notify HW the memory location of the receive buffer */
	ntb_set_mw_addr(nt->ndev, num_mw, mw->dma_addr);

	return 0;
}

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static void ntb_qp_link_cleanup(struct work_struct *work)
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{
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	struct ntb_transport_qp *qp = container_of(work,
						   struct ntb_transport_qp,
						   link_cleanup);
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	struct ntb_transport *nt = qp->transport;
	struct pci_dev *pdev = ntb_query_pdev(nt->ndev);

	if (qp->qp_link == NTB_LINK_DOWN) {
		cancel_delayed_work_sync(&qp->link_work);
		return;
	}

	if (qp->event_handler)
		qp->event_handler(qp->cb_data, NTB_LINK_DOWN);

	dev_info(&pdev->dev, "qp %d: Link Down\n", qp->qp_num);
	qp->qp_link = NTB_LINK_DOWN;

	if (nt->transport_link == NTB_LINK_UP)
		schedule_delayed_work(&qp->link_work,
				      msecs_to_jiffies(NTB_LINK_DOWN_TIMEOUT));
}

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static void ntb_qp_link_down(struct ntb_transport_qp *qp)
{
	schedule_work(&qp->link_cleanup);
}

static void ntb_transport_link_cleanup(struct work_struct *work)
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{
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	struct ntb_transport *nt = container_of(work, struct ntb_transport,
						link_cleanup);
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	int i;

	if (nt->transport_link == NTB_LINK_DOWN)
		cancel_delayed_work_sync(&nt->link_work);
	else
		nt->transport_link = NTB_LINK_DOWN;

	/* Pass along the info to any clients */
	for (i = 0; i < nt->max_qps; i++)
		if (!test_bit(i, &nt->qp_bitmap))
			ntb_qp_link_down(&nt->qps[i]);

	/* The scratchpad registers keep the values if the remote side
	 * goes down, blast them now to give them a sane value the next
	 * time they are accessed
	 */
	for (i = 0; i < MAX_SPAD; i++)
		ntb_write_local_spad(nt->ndev, i, 0);
}

static void ntb_transport_event_callback(void *data, enum ntb_hw_event event)
{
	struct ntb_transport *nt = data;

	switch (event) {
	case NTB_EVENT_HW_LINK_UP:
		schedule_delayed_work(&nt->link_work, 0);
		break;
	case NTB_EVENT_HW_LINK_DOWN:
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		schedule_work(&nt->link_cleanup);
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		break;
	default:
		BUG();
	}
}

static void ntb_transport_link_work(struct work_struct *work)
{
	struct ntb_transport *nt = container_of(work, struct ntb_transport,
						link_work.work);
	struct ntb_device *ndev = nt->ndev;
	struct pci_dev *pdev = ntb_query_pdev(ndev);
	u32 val;
	int rc, i;

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	/* send the local info, in the opposite order of the way we read it */
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	for (i = 0; i < ntb_max_mw(ndev); i++) {
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		rc = ntb_write_remote_spad(ndev, MW0_SZ_HIGH + (i * 2),
					   ntb_get_mw_size(ndev, i) >> 32);
		if (rc) {
			dev_err(&pdev->dev, "Error writing %u to remote spad %d\n",
				(u32)(ntb_get_mw_size(ndev, i) >> 32),
				MW0_SZ_HIGH + (i * 2));
			goto out;
		}
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		rc = ntb_write_remote_spad(ndev, MW0_SZ_LOW + (i * 2),
					   (u32) ntb_get_mw_size(ndev, i));
		if (rc) {
			dev_err(&pdev->dev, "Error writing %u to remote spad %d\n",
				(u32) ntb_get_mw_size(ndev, i),
				MW0_SZ_LOW + (i * 2));
			goto out;
		}
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	}

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	rc = ntb_write_remote_spad(ndev, NUM_MWS, ntb_max_mw(ndev));
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	if (rc) {
		dev_err(&pdev->dev, "Error writing %x to remote spad %d\n",
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			ntb_max_mw(ndev), NUM_MWS);
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		goto out;
	}

	rc = ntb_write_remote_spad(ndev, NUM_QPS, nt->max_qps);
	if (rc) {
		dev_err(&pdev->dev, "Error writing %x to remote spad %d\n",
			nt->max_qps, NUM_QPS);
		goto out;
	}

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	rc = ntb_write_remote_spad(ndev, VERSION, NTB_TRANSPORT_VERSION);
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	if (rc) {
		dev_err(&pdev->dev, "Error writing %x to remote spad %d\n",
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			NTB_TRANSPORT_VERSION, VERSION);
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		goto out;
	}

	/* Query the remote side for its info */
	rc = ntb_read_remote_spad(ndev, VERSION, &val);
	if (rc) {
		dev_err(&pdev->dev, "Error reading remote spad %d\n", VERSION);
		goto out;
	}

	if (val != NTB_TRANSPORT_VERSION)
		goto out;
	dev_dbg(&pdev->dev, "Remote version = %d\n", val);

	rc = ntb_read_remote_spad(ndev, NUM_QPS, &val);
	if (rc) {
		dev_err(&pdev->dev, "Error reading remote spad %d\n", NUM_QPS);
		goto out;
	}

	if (val != nt->max_qps)
		goto out;
	dev_dbg(&pdev->dev, "Remote max number of qps = %d\n", val);

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	rc = ntb_read_remote_spad(ndev, NUM_MWS, &val);
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	if (rc) {
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		dev_err(&pdev->dev, "Error reading remote spad %d\n", NUM_MWS);
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		goto out;
	}

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	if (val != ntb_max_mw(ndev))
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		goto out;
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	dev_dbg(&pdev->dev, "Remote number of mws = %d\n", val);
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	for (i = 0; i < ntb_max_mw(ndev); i++) {
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		u64 val64;
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		rc = ntb_read_remote_spad(ndev, MW0_SZ_HIGH + (i * 2), &val);
		if (rc) {
			dev_err(&pdev->dev, "Error reading remote spad %d\n",
				MW0_SZ_HIGH + (i * 2));
			goto out1;
		}
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		val64 = (u64) val << 32;
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		rc = ntb_read_remote_spad(ndev, MW0_SZ_LOW + (i * 2), &val);
		if (rc) {
			dev_err(&pdev->dev, "Error reading remote spad %d\n",
				MW0_SZ_LOW + (i * 2));
			goto out1;
		}

		val64 |= val;

		dev_dbg(&pdev->dev, "Remote MW%d size = %llu\n", i, val64);

		rc = ntb_set_mw(nt, i, val64);
		if (rc)
			goto out1;
	}
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	nt->transport_link = NTB_LINK_UP;

	for (i = 0; i < nt->max_qps; i++) {
		struct ntb_transport_qp *qp = &nt->qps[i];

		ntb_transport_setup_qp_mw(nt, i);

		if (qp->client_ready == NTB_LINK_UP)
			schedule_delayed_work(&qp->link_work, 0);
	}

	return;

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out1:
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	for (i = 0; i < ntb_max_mw(ndev); i++)
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		ntb_free_mw(nt, i);
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out:
	if (ntb_hw_link_status(ndev))
		schedule_delayed_work(&nt->link_work,
				      msecs_to_jiffies(NTB_LINK_DOWN_TIMEOUT));
}

static void ntb_qp_link_work(struct work_struct *work)
{
	struct ntb_transport_qp *qp = container_of(work,
						   struct ntb_transport_qp,
						   link_work.work);
	struct pci_dev *pdev = ntb_query_pdev(qp->ndev);
	struct ntb_transport *nt = qp->transport;
	int rc, val;

	WARN_ON(nt->transport_link != NTB_LINK_UP);

	rc = ntb_read_local_spad(nt->ndev, QP_LINKS, &val);
	if (rc) {
		dev_err(&pdev->dev, "Error reading spad %d\n", QP_LINKS);
		return;
	}

	rc = ntb_write_remote_spad(nt->ndev, QP_LINKS, val | 1 << qp->qp_num);
	if (rc)
		dev_err(&pdev->dev, "Error writing %x to remote spad %d\n",
			val | 1 << qp->qp_num, QP_LINKS);

	/* query remote spad for qp ready bits */
	rc = ntb_read_remote_spad(nt->ndev, QP_LINKS, &val);
	if (rc)
		dev_err(&pdev->dev, "Error reading remote spad %d\n", QP_LINKS);

	dev_dbg(&pdev->dev, "Remote QP link status = %x\n", val);

	/* See if the remote side is up */
	if (1 << qp->qp_num & val) {
		qp->qp_link = NTB_LINK_UP;

		dev_info(&pdev->dev, "qp %d: Link Up\n", qp->qp_num);
		if (qp->event_handler)
			qp->event_handler(qp->cb_data, NTB_LINK_UP);
	} else if (nt->transport_link == NTB_LINK_UP)
		schedule_delayed_work(&qp->link_work,
				      msecs_to_jiffies(NTB_LINK_DOWN_TIMEOUT));
}

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static int ntb_transport_init_queue(struct ntb_transport *nt,
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				     unsigned int qp_num)
{
	struct ntb_transport_qp *qp;
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	unsigned int num_qps_mw, tx_size;
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	u8 mw_num, mw_max;
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	u64 qp_offset;
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	mw_max = ntb_max_mw(nt->ndev);
	mw_num = QP_TO_MW(nt->ndev, qp_num);
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	qp = &nt->qps[qp_num];
	qp->qp_num = qp_num;
	qp->transport = nt;
	qp->ndev = nt->ndev;
	qp->qp_link = NTB_LINK_DOWN;
	qp->client_ready = NTB_LINK_DOWN;
	qp->event_handler = NULL;

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	if (nt->max_qps % mw_max && mw_num < nt->max_qps % mw_max)
		num_qps_mw = nt->max_qps / mw_max + 1;
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	else
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		num_qps_mw = nt->max_qps / mw_max;
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	tx_size = (unsigned int) ntb_get_mw_size(qp->ndev, mw_num) / num_qps_mw;
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	qp_offset = qp_num / mw_max * tx_size;
	qp->tx_mw = ntb_get_mw_vbase(nt->ndev, mw_num) + qp_offset;
	if (!qp->tx_mw)
		return -EINVAL;

	qp->tx_mw_phys = ntb_get_mw_base(qp->ndev, mw_num) + qp_offset;
	if (!qp->tx_mw_phys)
		return -EINVAL;

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	tx_size -= sizeof(struct ntb_rx_info);
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	qp->rx_info = qp->tx_mw + tx_size;
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	/* Due to housekeeping, there must be atleast 2 buffs */
	qp->tx_max_frame = min(transport_mtu, tx_size / 2);
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	qp->tx_max_entry = tx_size / qp->tx_max_frame;
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	if (ntb_query_debugfs(nt->ndev)) {
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		char debugfs_name[4];

		snprintf(debugfs_name, 4, "qp%d", qp_num);
		qp->debugfs_dir = debugfs_create_dir(debugfs_name,
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						 ntb_query_debugfs(nt->ndev));
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		qp->debugfs_stats = debugfs_create_file("stats", S_IRUSR,
							qp->debugfs_dir, qp,
							&ntb_qp_debugfs_stats);
	}

	INIT_DELAYED_WORK(&qp->link_work, ntb_qp_link_work);
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	INIT_WORK(&qp->link_cleanup, ntb_qp_link_cleanup);
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	spin_lock_init(&qp->ntb_rx_pend_q_lock);
	spin_lock_init(&qp->ntb_rx_free_q_lock);
	spin_lock_init(&qp->ntb_tx_free_q_lock);

	INIT_LIST_HEAD(&qp->rx_pend_q);
	INIT_LIST_HEAD(&qp->rx_free_q);
	INIT_LIST_HEAD(&qp->tx_free_q);
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	return 0;
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}

int ntb_transport_init(struct pci_dev *pdev)
{
	struct ntb_transport *nt;
	int rc, i;

	nt = kzalloc(sizeof(struct ntb_transport), GFP_KERNEL);
	if (!nt)
		return -ENOMEM;

	nt->ndev = ntb_register_transport(pdev, nt);
	if (!nt->ndev) {
		rc = -EIO;
		goto err;
	}

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	nt->mw = kcalloc(ntb_max_mw(nt->ndev), sizeof(struct ntb_transport_mw),
			 GFP_KERNEL);
	if (!nt->mw) {
		rc = -ENOMEM;
		goto err1;
	}

	if (max_num_clients)
		nt->max_qps = min(ntb_max_cbs(nt->ndev), max_num_clients);
	else
		nt->max_qps = min(ntb_max_cbs(nt->ndev), ntb_max_mw(nt->ndev));
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	nt->qps = kcalloc(nt->max_qps, sizeof(struct ntb_transport_qp),
			  GFP_KERNEL);
	if (!nt->qps) {
		rc = -ENOMEM;
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		goto err2;
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	}

	nt->qp_bitmap = ((u64) 1 << nt->max_qps) - 1;

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	for (i = 0; i < nt->max_qps; i++) {
		rc = ntb_transport_init_queue(nt, i);
		if (rc)
			goto err3;
	}
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	INIT_DELAYED_WORK(&nt->link_work, ntb_transport_link_work);
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	INIT_WORK(&nt->link_cleanup, ntb_transport_link_cleanup);
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	rc = ntb_register_event_callback(nt->ndev,
					 ntb_transport_event_callback);
	if (rc)
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		goto err3;
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	INIT_LIST_HEAD(&nt->client_devs);
	rc = ntb_bus_init(nt);
	if (rc)
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		goto err4;
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	if (ntb_hw_link_status(nt->ndev))
		schedule_delayed_work(&nt->link_work, 0);

	return 0;

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err4:
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	ntb_unregister_event_callback(nt->ndev);
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err3:
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	kfree(nt->qps);
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err2:
	kfree(nt->mw);
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err1:
	ntb_unregister_transport(nt->ndev);
err:
	kfree(nt);
	return rc;
}

void ntb_transport_free(void *transport)
{
	struct ntb_transport *nt = transport;
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	struct ntb_device *ndev = nt->ndev;
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	int i;

	nt->transport_link = NTB_LINK_DOWN;

	/* verify that all the qp's are freed */
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	for (i = 0; i < nt->max_qps; i++) {
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		if (!test_bit(i, &nt->qp_bitmap))
			ntb_transport_free_queue(&nt->qps[i]);
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		debugfs_remove_recursive(nt->qps[i].debugfs_dir);
	}
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	ntb_bus_remove(nt);

	cancel_delayed_work_sync(&nt->link_work);

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	ntb_unregister_event_callback(ndev);
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	for (i = 0; i < ntb_max_mw(ndev); i++)
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		ntb_free_mw(nt, i);
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	kfree(nt->qps);
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	kfree(nt->mw);
	ntb_unregister_transport(ndev);
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	kfree(nt);
}

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static void ntb_rx_copy_callback(void *data)
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{
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	struct ntb_queue_entry *entry = data;
	struct ntb_transport_qp *qp = entry->qp;
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	void *cb_data = entry->cb_data;
	unsigned int len = entry->len;
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	struct ntb_payload_header *hdr = entry->rx_hdr;

	/* Ensure that the data is fully copied out before clearing the flag */
	wmb();
	hdr->flags = 0;
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	iowrite32(entry->index, &qp->rx_info->entry);
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	ntb_list_add(&qp->ntb_rx_free_q_lock, &entry->entry, &qp->rx_free_q);
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	if (qp->rx_handler && qp->client_ready == NTB_LINK_UP)
		qp->rx_handler(qp, qp->cb_data, cb_data, len);
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}

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static void ntb_memcpy_rx(struct ntb_queue_entry *entry, void *offset)
{
	void *buf = entry->buf;
	size_t len = entry->len;

	memcpy(buf, offset, len);

	ntb_rx_copy_callback(entry);
}

static void ntb_async_rx(struct ntb_queue_entry *entry, void *offset,
			 size_t len)
{
	struct dma_async_tx_descriptor *txd;
	struct ntb_transport_qp *qp = entry->qp;
	struct dma_chan *chan = qp->dma_chan;
	struct dma_device *device;
	size_t pay_off, buff_off;
	dma_addr_t src, dest;
	dma_cookie_t cookie;
	void *buf = entry->buf;
	unsigned long flags;

	entry->len = len;

	if (!chan)
		goto err;

	if (len < copy_bytes) 
		goto err1;

	device = chan->device;
	pay_off = (size_t) offset & ~PAGE_MASK;
	buff_off = (size_t) buf & ~PAGE_MASK;

	if (!is_dma_copy_aligned(device, pay_off, buff_off, len))
		goto err1;

	dest = dma_map_single(device->dev, buf, len, DMA_FROM_DEVICE);
	if (dma_mapping_error(device->dev, dest))
		goto err1;

	src = dma_map_single(device->dev, offset, len, DMA_TO_DEVICE);
	if (dma_mapping_error(device->dev, src))
		goto err2;

	flags = DMA_COMPL_DEST_UNMAP_SINGLE | DMA_COMPL_SRC_UNMAP_SINGLE |
		DMA_PREP_INTERRUPT;
	txd = device->device_prep_dma_memcpy(chan, dest, src, len, flags);
	if (!txd)
		goto err3;

	txd->callback = ntb_rx_copy_callback;
	txd->callback_param = entry;

	cookie = dmaengine_submit(txd);
	if (dma_submit_error(cookie))
		goto err3;

	qp->last_cookie = cookie;

	qp->rx_async++;

	return;

err3:
	dma_unmap_single(device->dev, src, len, DMA_TO_DEVICE);
err2:
	dma_unmap_single(device->dev, dest, len, DMA_FROM_DEVICE);
err1:
	/* If the callbacks come out of order, the writing of the index to the
	 * last completed will be out of order.  This may result in the
	 * receive stalling forever.
	 */
	dma_sync_wait(chan, qp->last_cookie);
err:
	ntb_memcpy_rx(entry, offset);
	qp->rx_memcpy++;
}

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static int ntb_process_rxc(struct ntb_transport_qp *qp)
{
	struct ntb_payload_header *hdr;
	struct ntb_queue_entry *entry;
	void *offset;

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	offset = qp->rx_buff + qp->rx_max_frame * qp->rx_index;
	hdr = offset + qp->rx_max_frame - sizeof(struct ntb_payload_header);

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	entry = ntb_list_rm(&qp->ntb_rx_pend_q_lock, &qp->rx_pend_q);
	if (!entry) {
		dev_dbg(&ntb_query_pdev(qp->ndev)->dev,
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			"no buffer - HDR ver %u, len %d, flags %x\n",
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			hdr->ver, hdr->len, hdr->flags);
		qp->rx_err_no_buf++;
		return -ENOMEM;
	}

	if (!(hdr->flags & DESC_DONE_FLAG)) {
		ntb_list_add(&qp->ntb_rx_pend_q_lock, &entry->entry,
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			     &qp->rx_pend_q);
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		qp->rx_ring_empty++;
		return -EAGAIN;
	}

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	if (hdr->ver != (u32) qp->rx_pkts) {
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		dev_dbg(&ntb_query_pdev(qp->ndev)->dev,
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			"qp %d: version mismatch, expected %llu - got %u\n",
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			qp->qp_num, qp->rx_pkts, hdr->ver);
		ntb_list_add(&qp->ntb_rx_pend_q_lock, &entry->entry,
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			     &qp->rx_pend_q);
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		qp->rx_err_ver++;
		return -EIO;
	}

	if (hdr->flags & LINK_DOWN_FLAG) {
		ntb_qp_link_down(qp);

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		goto err;
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	}

	dev_dbg(&ntb_query_pdev(qp->ndev)->dev,
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		"rx offset %u, ver %u - %d payload received, buf size %d\n",
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		qp->rx_index, hdr->ver, hdr->len, entry->len);
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	qp->rx_bytes += hdr->len;
	qp->rx_pkts++;
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	if (hdr->len > entry->len) {
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		qp->rx_err_oflow++;
		dev_dbg(&ntb_query_pdev(qp->ndev)->dev,
			"RX overflow! Wanted %d got %d\n",
			hdr->len, entry->len);
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		goto err;
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	}

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	entry->index = qp->rx_index;
	entry->rx_hdr = hdr;

	ntb_async_rx(entry, offset, hdr->len);
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	qp->rx_index++;
	qp->rx_index %= qp->rx_max_entry;

	return 0;

err:
	ntb_list_add(&qp->ntb_rx_pend_q_lock, &entry->entry,
		     &qp->rx_pend_q);
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	/* Ensure that the data is fully copied out before clearing the flag */
	wmb();
	hdr->flags = 0;
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	iowrite32(qp->rx_index, &qp->rx_info->entry);
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	goto out;
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}

static void ntb_transport_rx(unsigned long data)
{
	struct ntb_transport_qp *qp = (struct ntb_transport_qp *)data;
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	int rc, i;
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	/* Limit the number of packets processed in a single interrupt to
	 * provide fairness to others
	 */
	for (i = 0; i < qp->rx_max_entry; i++) {
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		rc = ntb_process_rxc(qp);
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		if (rc)
			break;
	}
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	if (qp->dma_chan)
		dma_async_issue_pending(qp->dma_chan);
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}

static void ntb_transport_rxc_db(void *data, int db_num)
{
	struct ntb_transport_qp *qp = data;

	dev_dbg(&ntb_query_pdev(qp->ndev)->dev, "%s: doorbell %d received\n",
		__func__, db_num);

	tasklet_schedule(&qp->rx_work);
}

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static void ntb_tx_copy_callback(void *data)
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{
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