/*
 * 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) 2015 Intel Corporation. All rights reserved.
 *   Copyright(c) 2017 T-Platforms. 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) 2015 Intel Corporation. All rights reserved.
 *   Copyright(c) 2017 T-Platforms. 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.
 *
 * PCIe NTB Perf Linux driver
 */

/*
 * How to use this tool, by example.
 *
 * Assuming $DBG_DIR is something like:
 * '/sys/kernel/debug/ntb_perf/0000:00:03.0'
 * Suppose aside from local device there is at least one remote device
 * connected to NTB with index 0.
 *-----------------------------------------------------------------------------
 * Eg: install driver with specified chunk/total orders and dma-enabled flag
 *
 * root@self# insmod ntb_perf.ko chunk_order=19 total_order=28 use_dma
 *-----------------------------------------------------------------------------
 * Eg: check NTB ports (index) and MW mapping information
 *
 * root@self# cat $DBG_DIR/info
 *-----------------------------------------------------------------------------
 * Eg: start performance test with peer (index 0) and get the test metrics
 *
 * root@self# echo 0 > $DBG_DIR/run
 * root@self# cat $DBG_DIR/run
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/pci.h>
#include <linux/ktime.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/sizes.h>
#include <linux/workqueue.h>
#include <linux/debugfs.h>
#include <linux/random.h>
#include <linux/ntb.h>

#define DRIVER_NAME             "ntb_perf"
#define DRIVER_VERSION          "2.0"

MODULE_LICENSE("Dual BSD/GPL");
MODULE_VERSION(DRIVER_VERSION);
MODULE_AUTHOR("Dave Jiang <dave.jiang@intel.com>");
MODULE_DESCRIPTION("PCIe NTB Performance Measurement Tool");

#define MAX_THREADS_CNT         32
#define DEF_THREADS_CNT         1
#define MAX_CHUNK_SIZE          SZ_1M
#define MAX_CHUNK_ORDER         20 /* no larger than 1M */

#define DMA_TRIES               100
#define DMA_MDELAY              10

#define MSG_TRIES               500
#define MSG_UDELAY_LOW          1000
#define MSG_UDELAY_HIGH         2000

#define PERF_BUF_LEN 1024

static unsigned long max_mw_size;
module_param(max_mw_size, ulong, 0644);
MODULE_PARM_DESC(max_mw_size, "Upper limit of memory window size");

static unsigned char chunk_order = 19; /* 512K */
module_param(chunk_order, byte, 0644);
MODULE_PARM_DESC(chunk_order, "Data chunk order [2^n] to transfer");

static unsigned char total_order = 30; /* 1G */
module_param(total_order, byte, 0644);
MODULE_PARM_DESC(total_order, "Total data order [2^n] to transfer");

static bool use_dma; /* default to 0 */
module_param(use_dma, bool, 0644);
MODULE_PARM_DESC(use_dma, "Use DMA engine to measure performance");

/*==============================================================================
 *                         Perf driver data definition
 *==============================================================================
 */

enum perf_cmd {
        PERF_CMD_INVAL = -1,/* invalid spad command */
        PERF_CMD_SSIZE = 0, /* send out buffer size */
        PERF_CMD_RSIZE = 1, /* recv in  buffer size */
        PERF_CMD_SXLAT = 2, /* send in  buffer xlat */
        PERF_CMD_RXLAT = 3, /* recv out buffer xlat */
        PERF_CMD_CLEAR = 4, /* clear allocated memory */
        PERF_STS_DONE  = 5, /* init is done */
        PERF_STS_LNKUP = 6, /* link up state flag */
};

struct perf_ctx;

struct perf_peer {
        struct perf_ctx *perf;
        int pidx;
        int gidx;

        /* Outbound MW params */
        u64 outbuf_xlat;
        resource_size_t outbuf_size;
        void __iomem *outbuf;

        /* Inbound MW params */
        dma_addr_t inbuf_xlat;
        resource_size_t inbuf_size;
        void            *inbuf;

        /* NTB connection setup service */
        struct work_struct      service;
        unsigned long           sts;
};
#define to_peer_service(__work) \
        container_of(__work, struct perf_peer, service)

struct perf_thread {
        struct perf_ctx *perf;
        int tidx;

        /* DMA-based test sync parameters */
        atomic_t dma_sync;
        wait_queue_head_t dma_wait;
        struct dma_chan *dma_chan;

        /* Data source and measured statistics */
        void *src;
        u64 copied;
        ktime_t duration;
        int status;
        struct work_struct work;
};
#define to_thread_work(__work) \
        container_of(__work, struct perf_thread, work)

struct perf_ctx {
        struct ntb_dev *ntb;

        /* Global device index and peers descriptors */
        int gidx;
        int pcnt;
        struct perf_peer *peers;

        /* Performance measuring work-threads interface */
        unsigned long busy_flag;
        wait_queue_head_t twait;
        atomic_t tsync;
        u8 tcnt;
        struct perf_peer *test_peer;
        struct perf_thread threads[MAX_THREADS_CNT];

        /* Scratchpad/Message IO operations */
        int (*cmd_send)(struct perf_peer *peer, enum perf_cmd cmd, u64 data);
        int (*cmd_recv)(struct perf_ctx *perf, int *pidx, enum perf_cmd *cmd,
                        u64 *data);

        struct dentry *dbgfs_dir;
};

/*
 * Scratchpads-base commands interface
 */
#define PERF_SPAD_CNT(_pcnt) \
        (3*((_pcnt) + 1))
#define PERF_SPAD_CMD(_gidx) \
        (3*(_gidx))
#define PERF_SPAD_LDATA(_gidx) \
        (3*(_gidx) + 1)
#define PERF_SPAD_HDATA(_gidx) \
        (3*(_gidx) + 2)
#define PERF_SPAD_NOTIFY(_gidx) \
        (BIT_ULL(_gidx))

/*
 * Messages-base commands interface
 */
#define PERF_MSG_CNT            3
#define PERF_MSG_CMD            0
#define PERF_MSG_LDATA          1
#define PERF_MSG_HDATA          2

/*==============================================================================
 *                           Static data declarations
 *==============================================================================
 */

static struct dentry *perf_dbgfs_topdir;

static struct workqueue_struct *perf_wq __read_mostly;

/*==============================================================================
 *                  NTB cross-link commands execution service
 *==============================================================================
 */

static void perf_terminate_test(struct perf_ctx *perf);

static inline bool perf_link_is_up(struct perf_peer *peer)
{
        u64 link;

        link = ntb_link_is_up(peer->perf->ntb, NULL, NULL);
        return !!(link & BIT_ULL_MASK(peer->pidx));
}

static int perf_spad_cmd_send(struct perf_peer *peer, enum perf_cmd cmd,
                              u64 data)
{
        struct perf_ctx *perf = peer->perf;
        int try;
        u32 sts;

        dev_dbg(&perf->ntb->dev, "CMD send: %d 0x%llx\n", cmd, data);

        /*
         * Perform predefined number of attempts before give up.
         * We are sending the data to the port specific scratchpad, so
         * to prevent a multi-port access race-condition. Additionally
         * there is no need in local locking since only thread-safe
         * service work is using this method.
         */
        for (try = 0; try < MSG_TRIES; try++) {
                if (!perf_link_is_up(peer))
                        return -ENOLINK;

                sts = ntb_peer_spad_read(perf->ntb, peer->pidx,
                                         PERF_SPAD_CMD(perf->gidx));
                if (sts != PERF_CMD_INVAL) {
                        usleep_range(MSG_UDELAY_LOW, MSG_UDELAY_HIGH);
                        continue;
                }

                ntb_peer_spad_write(perf->ntb, peer->pidx,
                                    PERF_SPAD_LDATA(perf->gidx),
                                    lower_32_bits(data));
                ntb_peer_spad_write(perf->ntb, peer->pidx,
                                    PERF_SPAD_HDATA(perf->gidx),
                                    upper_32_bits(data));
                mmiowb();
                ntb_peer_spad_write(perf->ntb, peer->pidx,
                                    PERF_SPAD_CMD(perf->gidx),
                                    cmd);
                mmiowb();
                ntb_peer_db_set(perf->ntb, PERF_SPAD_NOTIFY(peer->gidx));

                dev_dbg(&perf->ntb->dev, "DB ring peer %#llx\n",
                        PERF_SPAD_NOTIFY(peer->gidx));

                break;
        }

        return try < MSG_TRIES ? 0 : -EAGAIN;
}

static int perf_spad_cmd_recv(struct perf_ctx *perf, int *pidx,
                              enum perf_cmd *cmd, u64 *data)
{
        struct perf_peer *peer;
        u32 val;

        ntb_db_clear(perf->ntb, PERF_SPAD_NOTIFY(perf->gidx));

        /*
         * We start scanning all over, since cleared DB may have been set
         * by any peer. Yes, it makes peer with smaller index being
         * serviced with greater priority, but it's convenient for spad
         * and message code unification and simplicity.
         */
        for (*pidx = 0; *pidx < perf->pcnt; (*pidx)++) {
                peer = &perf->peers[*pidx];

                if (!perf_link_is_up(peer))
                        continue;

                val = ntb_spad_read(perf->ntb, PERF_SPAD_CMD(peer->gidx));
                if (val == PERF_CMD_INVAL)
                        continue;

                *cmd = val;

                val = ntb_spad_read(perf->ntb, PERF_SPAD_LDATA(peer->gidx));
                *data = val;

                val = ntb_spad_read(perf->ntb, PERF_SPAD_HDATA(peer->gidx));
                *data |= (u64)val << 32;

                /* Next command can be retrieved from now */
                ntb_spad_write(perf->ntb, PERF_SPAD_CMD(peer->gidx),
                               PERF_CMD_INVAL);

                dev_dbg(&perf->ntb->dev, "CMD recv: %d 0x%llx\n", *cmd, *data);

                return 0;
        }

        return -ENODATA;
}

static int perf_msg_cmd_send(struct perf_peer *peer, enum perf_cmd cmd,
                             u64 data)
{
        struct perf_ctx *perf = peer->perf;
        int try, ret;
        u64 outbits;

        dev_dbg(&perf->ntb->dev, "CMD send: %d 0x%llx\n", cmd, data);

        /*
         * Perform predefined number of attempts before give up. Message
         * registers are free of race-condition problem when accessed
         * from different ports, so we don't need splitting registers
         * by global device index. We also won't have local locking,
         * since the method is used from service work only.
         */
        outbits = ntb_msg_outbits(perf->ntb);
        for (try = 0; try < MSG_TRIES; try++) {
                if (!perf_link_is_up(peer))
                        return -ENOLINK;

                ret = ntb_msg_clear_sts(perf->ntb, outbits);
                if (ret)
                        return ret;

                ntb_peer_msg_write(perf->ntb, peer->pidx, PERF_MSG_LDATA,
                                   lower_32_bits(data));

                if (ntb_msg_read_sts(perf->ntb) & outbits) {
                        usleep_range(MSG_UDELAY_LOW, MSG_UDELAY_HIGH);
                        continue;
                }

                ntb_peer_msg_write(perf->ntb, peer->pidx, PERF_MSG_HDATA,
                                   upper_32_bits(data));
                mmiowb();

                /* This call shall trigger peer message event */
                ntb_peer_msg_write(perf->ntb, peer->pidx, PERF_MSG_CMD, cmd);

                break;
        }

        return try < MSG_TRIES ? 0 : -EAGAIN;
}

static int perf_msg_cmd_recv(struct perf_ctx *perf, int *pidx,
                             enum perf_cmd *cmd, u64 *data)
{
        u64 inbits;
        u32 val;

        inbits = ntb_msg_inbits(perf->ntb);

        if (hweight64(ntb_msg_read_sts(perf->ntb) & inbits) < 3)
                return -ENODATA;

        val = ntb_msg_read(perf->ntb, pidx, PERF_MSG_CMD);
        *cmd = val;

        val = ntb_msg_read(perf->ntb, pidx, PERF_MSG_LDATA);
        *data = val;

        val = ntb_msg_read(perf->ntb, pidx, PERF_MSG_HDATA);
        *data |= (u64)val << 32;

        /* Next command can be retrieved from now */
        ntb_msg_clear_sts(perf->ntb, inbits);

        dev_dbg(&perf->ntb->dev, "CMD recv: %d 0x%llx\n", *cmd, *data);

        return 0;
}

static int perf_cmd_send(struct perf_peer *peer, enum perf_cmd cmd, u64 data)
{
        struct perf_ctx *perf = peer->perf;

        if (cmd == PERF_CMD_SSIZE || cmd == PERF_CMD_SXLAT)
                return perf->cmd_send(peer, cmd, data);

        dev_err(&perf->ntb->dev, "Send invalid command\n");
        return -EINVAL;
}

static int perf_cmd_exec(struct perf_peer *peer, enum perf_cmd cmd)
{
        switch (cmd) {
        case PERF_CMD_SSIZE:
        case PERF_CMD_RSIZE:
        case PERF_CMD_SXLAT:
        case PERF_CMD_RXLAT:
        case PERF_CMD_CLEAR:
                break;
        default:
                dev_err(&peer->perf->ntb->dev, "Exec invalid command\n");
                return -EINVAL;
        }

        /* No need of memory barrier, since bit ops have invernal lock */
        set_bit(cmd, &peer->sts);

        dev_dbg(&peer->perf->ntb->dev, "CMD exec: %d\n", cmd);

        (void)queue_work(system_highpri_wq, &peer->service);

        return 0;
}

static int perf_cmd_recv(struct perf_ctx *perf)
{
        struct perf_peer *peer;
        int ret, pidx, cmd;
        u64 data;

        while (!(ret = perf->cmd_recv(perf, &pidx, &cmd, &data))) {
                peer = &perf->peers[pidx];

                switch (cmd) {
                case PERF_CMD_SSIZE:
                        peer->inbuf_size = data;
                        return perf_cmd_exec(peer, PERF_CMD_RSIZE);
                case PERF_CMD_SXLAT:
                        peer->outbuf_xlat = data;
                        return perf_cmd_exec(peer, PERF_CMD_RXLAT);
                default:
                        dev_err(&perf->ntb->dev, "Recv invalid command\n");
                        return -EINVAL;
                }
        }

        /* Return 0 if no data left to process, otherwise an error */
        return ret == -ENODATA ? 0 : ret;
}

static void perf_link_event(void *ctx)
{
        struct perf_ctx *perf = ctx;
        struct perf_peer *peer;
        bool lnk_up;
        int pidx;

        for (pidx = 0; pidx < perf->pcnt; pidx++) {
                peer = &perf->peers[pidx];

                lnk_up = perf_link_is_up(peer);

                if (lnk_up &&
                    !test_and_set_bit(PERF_STS_LNKUP, &peer->sts)) {
                        perf_cmd_exec(peer, PERF_CMD_SSIZE);
                } else if (!lnk_up &&
                           test_and_clear_bit(PERF_STS_LNKUP, &peer->sts)) {
                        perf_cmd_exec(peer, PERF_CMD_CLEAR);
                }
        }
}

static void perf_db_event(void *ctx, int vec)
{
        struct perf_ctx *perf = ctx;

        dev_dbg(&perf->ntb->dev, "DB vec %d mask %#llx bits %#llx\n", vec,
                ntb_db_vector_mask(perf->ntb, vec), ntb_db_read(perf->ntb));

        /* Just receive all available commands */
        (void)perf_cmd_recv(perf);
}

static void perf_msg_event(void *ctx)
{
        struct perf_ctx *perf = ctx;

        dev_dbg(&perf->ntb->dev, "Msg status bits %#llx\n",
                ntb_msg_read_sts(perf->ntb));

        /* Messages are only sent one-by-one */
        (void)perf_cmd_recv(perf);
}

static const struct ntb_ctx_ops perf_ops = {
        .link_event = perf_link_event,
        .db_event = perf_db_event,
        .msg_event = perf_msg_event
};

static void perf_free_outbuf(struct perf_peer *peer)
{
        (void)ntb_peer_mw_clear_trans(peer->perf->ntb, peer->pidx, peer->gidx);
}

static int perf_setup_outbuf(struct perf_peer *peer)
{
        struct perf_ctx *perf = peer->perf;
        int ret;

        /* Outbuf size can be unaligned due to custom max_mw_size */
        ret = ntb_peer_mw_set_trans(perf->ntb, peer->pidx, peer->gidx,
                                    peer->outbuf_xlat, peer->outbuf_size);
        if (ret) {
                dev_err(&perf->ntb->dev, "Failed to set outbuf translation\n");
                return ret;
        }

        /* Initialization is finally done */
        set_bit(PERF_STS_DONE, &peer->sts);

        return 0;
}

static void perf_free_inbuf(struct perf_peer *peer)
{
        if (!peer->inbuf)
                return;

        (void)ntb_mw_clear_trans(peer->perf->ntb, peer->pidx, peer->gidx);
        dma_free_coherent(&peer->perf->ntb->dev, peer->inbuf_size,
                          peer->inbuf, peer->inbuf_xlat);
        peer->inbuf = NULL;
}

static int perf_setup_inbuf(struct perf_peer *peer)
{
        resource_size_t xlat_align, size_align, size_max;
        struct perf_ctx *perf = peer->perf;
        int ret;

        /* Get inbound MW parameters */
        ret = ntb_mw_get_align(perf->ntb, peer->pidx, perf->gidx,
                               &xlat_align, &size_align, &size_max);
        if (ret) {
                dev_err(&perf->ntb->dev, "Couldn't get inbuf restrictions\n");
                return ret;
        }

        if (peer->inbuf_size > size_max) {
                dev_err(&perf->ntb->dev, "Too big inbuf size %pa > %pa\n",
                        &peer->inbuf_size, &size_max);
                return -EINVAL;
        }

        peer->inbuf_size = round_up(peer->inbuf_size, size_align);

        perf_free_inbuf(peer);

        peer->inbuf = dma_alloc_coherent(&perf->ntb->dev, peer->inbuf_size,
                                         &peer->inbuf_xlat, GFP_KERNEL);
        if (!peer->inbuf) {
                dev_err(&perf->ntb->dev, "Failed to alloc inbuf of %pa\n",
                        &peer->inbuf_size);
                return -ENOMEM;
        }
        if (!IS_ALIGNED(peer->inbuf_xlat, xlat_align)) {
                dev_err(&perf->ntb->dev, "Unaligned inbuf allocated\n");
                goto err_free_inbuf;
        }

        ret = ntb_mw_set_trans(perf->ntb, peer->pidx, peer->gidx,
                               peer->inbuf_xlat, peer->inbuf_size);
        if (ret) {
                dev_err(&perf->ntb->dev, "Failed to set inbuf translation\n");
                goto err_free_inbuf;
        }

        /*
         * We submit inbuf xlat transmission cmd for execution here to follow
         * the code architecture, even though this method is called from service
         * work itself so the command will be executed right after it returns.
         */
        (void)perf_cmd_exec(peer, PERF_CMD_SXLAT);

        return 0;

err_free_inbuf:
        perf_free_inbuf(peer);

        return ret;
}

static void perf_service_work(struct work_struct *work)
{
        struct perf_peer *peer = to_peer_service(work);

        if (test_and_clear_bit(PERF_CMD_SSIZE, &peer->sts))
                perf_cmd_send(peer, PERF_CMD_SSIZE, peer->outbuf_size);

        if (test_and_clear_bit(PERF_CMD_RSIZE, &peer->sts))
                perf_setup_inbuf(peer);

        if (test_and_clear_bit(PERF_CMD_SXLAT, &peer->sts))
                perf_cmd_send(peer, PERF_CMD_SXLAT, peer->inbuf_xlat);

        if (test_and_clear_bit(PERF_CMD_RXLAT, &peer->sts))
                perf_setup_outbuf(peer);

        if (test_and_clear_bit(PERF_CMD_CLEAR, &peer->sts)) {
                clear_bit(PERF_STS_DONE, &peer->sts);
                if (test_bit(0, &peer->perf->busy_flag) &&
                    peer == peer->perf->test_peer) {
                        dev_warn(&peer->perf->ntb->dev,
                                "Freeing while test on-fly\n");
                        perf_terminate_test(peer->perf);
                }
                perf_free_outbuf(peer);
                perf_free_inbuf(peer);
        }
}

static int perf_init_service(struct perf_ctx *perf)
{
        u64 mask;

        if (ntb_peer_mw_count(perf->ntb) < perf->pcnt + 1) {
                dev_err(&perf->ntb->dev, "Not enough memory windows\n");
                return -EINVAL;
        }

        if (ntb_msg_count(perf->ntb) >= PERF_MSG_CNT) {
                perf->cmd_send = perf_msg_cmd_send;
                perf->cmd_recv = perf_msg_cmd_recv;

                dev_dbg(&perf->ntb->dev, "Message service initialized\n");

                return 0;
        }

        dev_dbg(&perf->ntb->dev, "Message service unsupported\n");

        mask = GENMASK_ULL(perf->pcnt, 0);
        if (ntb_spad_count(perf->ntb) >= PERF_SPAD_CNT(perf->pcnt) &&
            (ntb_db_valid_mask(perf->ntb) & mask) == mask) {
                perf->cmd_send = perf_spad_cmd_send;
                perf->cmd_recv = perf_spad_cmd_recv;

                dev_dbg(&perf->ntb->dev, "Scratchpad service initialized\n");

                return 0;
        }

        dev_dbg(&perf->ntb->dev, "Scratchpad service unsupported\n");

        dev_err(&perf->ntb->dev, "Command services unsupported\n");

        return -EINVAL;
}

static int perf_enable_service(struct perf_ctx *perf)
{
        u64 mask, incmd_bit;
        int ret, sidx, scnt;

        mask = ntb_db_valid_mask(perf->ntb);
        (void)ntb_db_set_mask(perf->ntb, mask);

        ret = ntb_set_ctx(perf->ntb, perf, &perf_ops);
        if (ret)
                return ret;

        if (perf->cmd_send == perf_msg_cmd_send) {
                u64 inbits, outbits;

                inbits = ntb_msg_inbits(perf->ntb);
                outbits = ntb_msg_outbits(perf->ntb);
                (void)ntb_msg_set_mask(perf->ntb, inbits | outbits);

                incmd_bit = BIT_ULL(__ffs64(inbits));
                ret = ntb_msg_clear_mask(perf->ntb, incmd_bit);

                dev_dbg(&perf->ntb->dev, "MSG sts unmasked %#llx\n", incmd_bit);
        } else {
                scnt = ntb_spad_count(perf->ntb);
                for (sidx = 0; sidx < scnt; sidx++)
                        ntb_spad_write(perf->ntb, sidx, PERF_CMD_INVAL);
                incmd_bit = PERF_SPAD_NOTIFY(perf->gidx);
                ret = ntb_db_clear_mask(perf->ntb, incmd_bit);

                dev_dbg(&perf->ntb->dev, "DB bits unmasked %#llx\n", incmd_bit);
        }
        if (ret) {
                ntb_clear_ctx(perf->ntb);
                return ret;
        }

        ntb_link_enable(perf->ntb, NTB_SPEED_AUTO, NTB_WIDTH_AUTO);
        /* Might be not necessary */
        ntb_link_event(perf->ntb);

        return 0;
}

static void perf_disable_service(struct perf_ctx *perf)
{
        int pidx;

        ntb_link_disable(perf->ntb);

        if (perf->cmd_send == perf_msg_cmd_send) {
                u64 inbits;

                inbits = ntb_msg_inbits(perf->ntb);
                (void)ntb_msg_set_mask(perf->ntb, inbits);
        } else {
                (void)ntb_db_set_mask(perf->ntb, PERF_SPAD_NOTIFY(perf->gidx));
        }

        ntb_clear_ctx(perf->ntb);

        for (pidx = 0; pidx < perf->pcnt; pidx++)
                perf_cmd_exec(&perf->peers[pidx], PERF_CMD_CLEAR);

        for (pidx = 0; pidx < perf->pcnt; pidx++)
                flush_work(&perf->peers[pidx].service);
}

/*==============================================================================
 *                      Performance measuring work-thread
 *==============================================================================
 */

static void perf_dma_copy_callback(void *data)
{
        struct perf_thread *pthr = data;

        atomic_dec(&pthr->dma_sync);
        wake_up(&pthr->dma_wait);
}

static int perf_copy_chunk(struct perf_thread *pthr,
                           void __iomem *dst, void *src, size_t len)
{
        struct dma_async_tx_descriptor *tx;
        struct dmaengine_unmap_data *unmap;
        struct device *dma_dev;
        int try = 0, ret = 0;

        if (!use_dma) {
                memcpy_toio(dst, src, len);
                goto ret_check_tsync;
        }

        dma_dev = pthr->dma_chan->device->dev;

        if (!is_dma_copy_aligned(pthr->dma_chan->device, offset_in_page(src),
                                 offset_in_page(dst), len))
                return -EIO;

        unmap = dmaengine_get_unmap_data(dma_dev, 2, GFP_NOWAIT);
        if (!unmap)
                return -ENOMEM;

        unmap->len = len;
        unmap->addr[0] = dma_map_page(dma_dev, virt_to_page(src),
                offset_in_page(src), len, DMA_TO_DEVICE);
        if (dma_mapping_error(dma_dev, unmap->addr[0])) {
                ret = -EIO;
                goto err_free_resource;
        }
        unmap->to_cnt = 1;

        unmap->addr[1] = dma_map_page(dma_dev, virt_to_page(dst),
                offset_in_page(dst), len, DMA_FROM_DEVICE);
        if (dma_mapping_error(dma_dev, unmap->addr[1])) {
                ret = -EIO;
                goto err_free_resource;
        }
        unmap->from_cnt = 1;

        do {
                tx = dmaengine_prep_dma_memcpy(pthr->dma_chan, unmap->addr[1],
                        unmap->addr[0], len, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
                if (!tx)
                        msleep(DMA_MDELAY);
        } while (!tx && (try++ < DMA_TRIES));

        if (!tx) {
                ret = -EIO;
                goto err_free_resource;
        }

        tx->callback = perf_dma_copy_callback;
        tx->callback_param = pthr;
        dma_set_unmap(tx, unmap);

        ret = dma_submit_error(dmaengine_submit(tx));
        if (ret) {
                dmaengine_unmap_put(unmap);
                goto err_free_resource;
        }

        dmaengine_unmap_put(unmap);

        atomic_inc(&pthr->dma_sync);
        dma_async_issue_pending(pthr->dma_chan);

ret_check_tsync:
        return likely(atomic_read(&pthr->perf->tsync) > 0) ? 0 : -EINTR;

err_free_resource:
        dmaengine_unmap_put(unmap);

        return ret;
}

static bool perf_dma_filter(struct dma_chan *chan, void *data)
{
        struct perf_ctx *perf = data;
        int node;

        node = dev_to_node(&perf->ntb->dev);

        return node == NUMA_NO_NODE || node == dev_to_node(chan->device->dev);
}

static int perf_init_test(struct perf_thread *pthr)
{
        struct perf_ctx *perf = pthr->perf;
        dma_cap_mask_t dma_mask;

        pthr->src = kmalloc_node(perf->test_peer->outbuf_size, GFP_KERNEL,
                                 dev_to_node(&perf->ntb->dev));
        if (!pthr->src)
                return -ENOMEM;

        get_random_bytes(pthr->src, perf->test_peer->outbuf_size);

        if (!use_dma)
                return 0;

        dma_cap_zero(dma_mask);
        dma_cap_set(DMA_MEMCPY, dma_mask);
        pthr->dma_chan = dma_request_channel(dma_mask, perf_dma_filter, perf);
        if (!pthr->dma_chan) {
                dev_err(&perf->ntb->dev, "%d: Failed to get DMA channel\n",
                        pthr->tidx);
                atomic_dec(&perf->tsync);
                wake_up(&perf->twait);
                kfree(pthr->src);
                return -ENODEV;
        }

        atomic_set(&pthr->dma_sync, 0);

        return 0;
}

static int perf_run_test(struct perf_thread *pthr)
{
        struct perf_peer *peer = pthr->perf->test_peer;
        struct perf_ctx *perf = pthr->perf;
        void __iomem *flt_dst, *bnd_dst;
        u64 total_size, chunk_size;
        void *flt_src;
        int ret = 0;

        total_size = 1ULL << total_order;
        chunk_size = 1ULL << chunk_order;
        chunk_size = min_t(u64, peer->outbuf_size, chunk_size);

        flt_src = pthr->src;
        bnd_dst = peer->outbuf + peer->outbuf_size;
        flt_dst = peer->outbuf;

        pthr->duration = ktime_get();

        /* Copied field is cleared on test launch stage */
        while (pthr->copied < total_size) {
                ret = perf_copy_chunk(pthr, flt_dst, flt_src, chunk_size);
                if (ret) {
                        dev_err(&perf->ntb->dev, "%d: Got error %d on test\n",
                                pthr->tidx, ret);
                        return ret;
                }

                pthr->copied += chunk_size;

                flt_dst += chunk_size;
                flt_src += chunk_size;
                if (flt_dst >= bnd_dst || flt_dst < peer->outbuf) {
                        flt_dst = peer->outbuf;
                        flt_src = pthr->src;
                }

                /* Give up CPU to give a chance for other threads to use it */
                schedule();
        }

        return 0;
}

static int perf_sync_test(struct perf_thread *pthr)
{
        struct perf_ctx *perf = pthr->perf;

        if (!use_dma)
                goto no_dma_ret;

        wait_event(pthr->dma_wait,
                   (atomic_read(&pthr->dma_sync) == 0 ||
                    atomic_read(&perf->tsync) < 0));

        if (atomic_read(&perf->tsync) < 0)
                return -EINTR;

no_dma_ret:
        pthr->duration = ktime_sub(ktime_get(), pthr->duration);

        dev_dbg(&perf->ntb->dev, "%d: copied %llu bytes\n",
                pthr->tidx, pthr->copied);

        dev_dbg(&perf->ntb->dev, "%d: lasted %llu usecs\n",
                pthr->tidx, ktime_to_us(pthr->duration));

        dev_dbg(&perf->ntb->dev, "%d: %llu MBytes/s\n", pthr->tidx,
                div64_u64(pthr->copied, ktime_to_us(pthr->duration)));

        return 0;
}

static void perf_clear_test(struct perf_thread *pthr)
{
        struct perf_ctx *perf = pthr->perf;

        if (!use_dma)
                goto no_dma_notify;

        /*
         * If test finished without errors, termination isn't needed.
         * We call it anyway just to be sure of the transfers completion.
         */
        (void)dmaengine_terminate_sync(pthr->dma_chan);

        dma_release_channel(pthr->dma_chan);

no_dma_notify:
        atomic_dec(&perf->tsync);
        wake_up(&perf->twait);
        kfree(pthr->src);
}

static void perf_thread_work(struct work_struct *work)
{
        struct perf_thread *pthr = to_thread_work(work);
        int ret;

        /*
         * Perform stages in compliance with use_dma flag value.
         * Test status is changed only if error happened, otherwise
         * status -ENODATA is kept while test is on-fly. Results
         * synchronization is performed only if test fininshed
         * without an error or interruption.
         */
        ret = perf_init_test(pthr);
        if (ret) {
                pthr->status = ret;
                return;

        }

        ret = perf_run_test(pthr);
        if (ret) {
                pthr->status = ret;
                goto err_clear_test;
        }

        pthr->status = perf_sync_test(pthr);

err_clear_test:
        perf_clear_test(pthr);
}

static int perf_set_tcnt(struct perf_ctx *perf, u8 tcnt)
{
        if (tcnt == 0 || tcnt > MAX_THREADS_CNT)
                return -EINVAL;

        if (test_and_set_bit_lock(0, &perf->busy_flag))
                return -EBUSY;

        perf->tcnt = tcnt;

        clear_bit_unlock(0, &perf->busy_flag);

        return 0;
}

static void perf_terminate_test(struct perf_ctx *perf)
{
        int tidx;

        atomic_set(&perf->tsync, -1);
        wake_up(&perf->twait);

        for (tidx = 0; tidx < MAX_THREADS_CNT; tidx++) {
                wake_up(&perf->threads[tidx].dma_wait);
                cancel_work_sync(&perf->threads[tidx].work);
        }
}

static int perf_submit_test(struct perf_peer *peer)
{
        struct perf_ctx *perf = peer->perf;
        struct perf_thread *pthr;
        int tidx, ret;

        if (!test_bit(PERF_STS_DONE, &peer->sts))
                return -ENOLINK;

        if (test_and_set_bit_lock(0, &perf->busy_flag))
                return -EBUSY;

        perf->test_peer = peer;
        atomic_set(&perf->tsync, perf->tcnt);

        for (tidx = 0; tidx < MAX_THREADS_CNT; tidx++) {
                pthr = &perf->threads[tidx];

                pthr->status = -ENODATA;
                pthr->copied = 0;
                pthr->duration = ktime_set(0, 0);
                if (tidx < perf->tcnt)
                        (void)queue_work(perf_wq, &pthr->work);
        }

        ret = wait_event_interruptible(perf->twait,
                                       atomic_read(&perf->tsync) <= 0);
        if (ret == -ERESTARTSYS) {
                perf_terminate_test(perf);
                ret = -EINTR;
        }

        clear_bit_unlock(0, &perf->busy_flag);

        return ret;
}

static int perf_read_stats(struct perf_ctx *perf, char *buf,
                           size_t size, ssize_t *pos)
{
        struct perf_thread *pthr;
        int tidx;

        if (test_and_set_bit_lock(0, &perf->busy_flag))
                return -EBUSY;

        (*pos) += scnprintf(buf + *pos, size - *pos,
                "    Peer %d test statistics:\n", perf->test_peer->pidx);

        for (tidx = 0; tidx < MAX_THREADS_CNT; tidx++) {
                pthr = &perf->threads[tidx];

                if (pthr->status == -ENODATA)
                        continue;

                if (pthr->status) {
                        (*pos) += scnprintf(buf + *pos, size - *pos,
                                "%d: error status %d\n", tidx, pthr->status);
                        continue;
                }

                (*pos) += scnprintf(buf + *pos, size - *pos,
                        "%d: copied %llu bytes in %llu usecs, %llu MBytes/s\n",
                        tidx, pthr->copied, ktime_to_us(pthr->duration),
                        div64_u64(pthr->copied, ktime_to_us(pthr->duration)));
        }

        clear_bit_unlock(0, &perf->busy_flag);

        return 0;
}

static void perf_init_threads(struct perf_ctx *perf)
{
        struct perf_thread *pthr;
        int tidx;

        perf->tcnt = DEF_THREADS_CNT;
        perf->test_peer = &perf->peers[0];
        init_waitqueue_head(&perf->twait);

        for (tidx = 0; tidx < MAX_THREADS_CNT; tidx++) {
                pthr = &perf->threads[tidx];

                pthr->perf = perf;
                pthr->tidx = tidx;
                pthr->status = -ENODATA;
                init_waitqueue_head(&pthr->dma_wait);
                INIT_WORK(&pthr->work, perf_thread_work);
        }
}

static void perf_clear_threads(struct perf_ctx *perf)
{
        perf_terminate_test(perf);
}

/*==============================================================================
 *                               DebugFS nodes
 *==============================================================================
 */

static ssize_t perf_dbgfs_read_info(struct file *filep, char __user *ubuf,
                                    size_t size, loff_t *offp)
{
        struct perf_ctx *perf = filep->private_data;
        struct perf_peer *peer;
        size_t buf_size;
        ssize_t pos = 0;
        int ret, pidx;
        char *buf;

        buf_size = min_t(size_t, size, 0x1000U);

        buf = kmalloc(buf_size, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        pos += scnprintf(buf + pos, buf_size - pos,
                "    Performance measuring tool info:\n\n");

        pos += scnprintf(buf + pos, buf_size - pos,
                "Local port %d, Global index %d\n", ntb_port_number(perf->ntb),
                perf->gidx);
        pos += scnprintf(buf + pos, buf_size - pos, "Test status: ");
        if (test_bit(0, &perf->busy_flag)) {
                pos += scnprintf(buf + pos, buf_size - pos,
                        "on-fly with port %d (%d)\n",
                        ntb_peer_port_number(perf->ntb, perf->test_peer->pidx),
                        perf->test_peer->pidx);
        } else {
                pos += scnprintf(buf + pos, buf_size - pos, "idle\n");
        }

        for (pidx = 0; pidx < perf->pcnt; pidx++) {
                peer = &perf->peers[pidx];

                pos += scnprintf(buf + pos, buf_size - pos,
                        "Port %d (%d), Global index %d:\n",
                        ntb_peer_port_number(perf->ntb, peer->pidx), peer->pidx,
                        peer->gidx);

                pos += scnprintf(buf + pos, buf_size - pos,
                        "\tLink status: %s\n",
                        test_bit(PERF_STS_LNKUP, &peer->sts) ? "up" : "down");

                pos += scnprintf(buf + pos, buf_size - pos,
                        "\tOut buffer addr 0x%pK\n", peer->outbuf);

                pos += scnprintf(buf + pos, buf_size - pos,
                        "\tOut buffer size %pa\n", &peer->outbuf_size);

                pos += scnprintf(buf + pos, buf_size - pos,
                        "\tOut buffer xlat 0x%016llx[p]\n", peer->outbuf_xlat);

                if (!peer->inbuf) {
                        pos += scnprintf(buf + pos, buf_size - pos,
                                "\tIn buffer addr: unallocated\n");
                        continue;
                }

                pos += scnprintf(buf + pos, buf_size - pos,
                        "\tIn buffer addr 0x%pK\n", peer->inbuf);

                pos += scnprintf(buf + pos, buf_size - pos,
                        "\tIn buffer size %pa\n", &peer->inbuf_size);

                pos += scnprintf(buf + pos, buf_size - pos,
                        "\tIn buffer xlat %pad[p]\n", &peer->inbuf_xlat);
        }

        ret = simple_read_from_buffer(ubuf, size, offp, buf, pos);
        kfree(buf);

        return ret;
}

static const struct file_operations perf_dbgfs_info = {
        .open = simple_open,
        .read = perf_dbgfs_read_info
};

static ssize_t perf_dbgfs_read_run(struct file *filep, char __user *ubuf,
                                   size_t size, loff_t *offp)
{
        struct perf_ctx *perf = filep->private_data;
        ssize_t ret, pos = 0;
        char *buf;

        buf = kmalloc(PERF_BUF_LEN, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        ret = perf_read_stats(perf, buf, PERF_BUF_LEN, &pos);
        if (ret)
                goto err_free;

        ret = simple_read_from_buffer(ubuf, size, offp, buf, pos);
err_free:
        kfree(buf);

        return ret;
}

static ssize_t perf_dbgfs_write_run(struct file *filep, const char __user *ubuf,
                                    size_t size, loff_t *offp)
{
        struct perf_ctx *perf = filep->private_data;
        struct perf_peer *peer;
        int pidx, ret;

        ret = kstrtoint_from_user(ubuf, size, 0, &pidx);
        if (ret)
                return ret;

        if (pidx < 0 || pidx >= perf->pcnt)
                return -EINVAL;

        peer = &perf->peers[pidx];

        ret = perf_submit_test(peer);
        if (ret)
                return ret;

        return size;
}

static const struct file_operations perf_dbgfs_run = {
        .open = simple_open,
        .read = perf_dbgfs_read_run,
        .write = perf_dbgfs_write_run
};

static ssize_t perf_dbgfs_read_tcnt(struct file *filep, char __user *ubuf,
                                    size_t size, loff_t *offp)
{
        struct perf_ctx *perf = filep->private_data;
        char buf[8];
        ssize_t pos;

        pos = scnprintf(buf, sizeof(buf), "%hhu\n", perf->tcnt);

        return simple_read_from_buffer(ubuf, size, offp, buf, pos);
}

static ssize_t perf_dbgfs_write_tcnt(struct file *filep,
                                     const char __user *ubuf,
                                     size_t size, loff_t *offp)
{
        struct perf_ctx *perf = filep->private_data;
        int ret;
        u8 val;

        ret = kstrtou8_from_user(ubuf, size, 0, &val);
        if (ret)
                return ret;

        ret = perf_set_tcnt(perf, val);
        if (ret)
                return ret;

        return size;
}

static const struct file_operations perf_dbgfs_tcnt = {
        .open = simple_open,
        .read = perf_dbgfs_read_tcnt,
        .write = perf_dbgfs_write_tcnt
};

static void perf_setup_dbgfs(struct perf_ctx *perf)
{
        struct pci_dev *pdev = perf->ntb->pdev;

        perf->dbgfs_dir = debugfs_create_dir(pci_name(pdev), perf_dbgfs_topdir);
        if (!perf->dbgfs_dir) {
                dev_warn(&perf->ntb->dev, "DebugFS unsupported\n");
                return;
        }

        debugfs_create_file("info", 0600, perf->dbgfs_dir, perf,
                            &perf_dbgfs_info);

        debugfs_create_file("run", 0600, perf->dbgfs_dir, perf,
                            &perf_dbgfs_run);

        debugfs_create_file("threads_count", 0600, perf->dbgfs_dir, perf,
                            &perf_dbgfs_tcnt);

        /* They are made read-only for test exec safety and integrity */
        debugfs_create_u8("chunk_order", 0500, perf->dbgfs_dir, &chunk_order);

        debugfs_create_u8("total_order", 0500, perf->dbgfs_dir, &total_order);

        debugfs_create_bool("use_dma", 0500, perf->dbgfs_dir, &use_dma);
}

static void perf_clear_dbgfs(struct perf_ctx *perf)
{
        debugfs_remove_recursive(perf->dbgfs_dir);
}

/*==============================================================================
 *                        Basic driver initialization
 *==============================================================================
 */

static struct perf_ctx *perf_create_data(struct ntb_dev *ntb)
{
        struct perf_ctx *perf;

        perf = devm_kzalloc(&ntb->dev, sizeof(*perf), GFP_KERNEL);
        if (!perf)
                return ERR_PTR(-ENOMEM);

        perf->pcnt = ntb_peer_port_count(ntb);
        perf->peers = devm_kcalloc(&ntb->dev, perf->pcnt, sizeof(*perf->peers),
                                  GFP_KERNEL);
        if (!perf->peers)
                return ERR_PTR(-ENOMEM);

        perf->ntb = ntb;

        return perf;
}

static int perf_setup_peer_mw(struct perf_peer *peer)
{
        struct perf_ctx *perf = peer->perf;
        phys_addr_t phys_addr;
        int ret;

        /* Get outbound MW parameters and map it */
        ret = ntb_peer_mw_get_addr(perf->ntb, peer->gidx, &phys_addr,
                                   &peer->outbuf_size);
        if (ret)
                return ret;

        peer->outbuf = devm_ioremap_wc(&perf->ntb->dev, phys_addr,
                                        peer->outbuf_size);
        if (!peer->outbuf)
                return -ENOMEM;

        if (max_mw_size && peer->outbuf_size > max_mw_size) {
                peer->outbuf_size = max_mw_size;
                dev_warn(&peer->perf->ntb->dev,
                        "Peer %d outbuf reduced to %pa\n", peer->pidx,
                        &peer->outbuf_size);
        }

        return 0;
}

static int perf_init_peers(struct perf_ctx *perf)
{
        struct perf_peer *peer;
        int pidx, lport, ret;

        lport = ntb_port_number(perf->ntb);
        perf->gidx = -1;
        for (pidx = 0; pidx < perf->pcnt; pidx++) {
                peer = &perf->peers[pidx];

                peer->perf = perf;
                peer->pidx = pidx;
                if (lport < ntb_peer_port_number(perf->ntb, pidx)) {
                        if (perf->gidx == -1)
                                perf->gidx = pidx;
                        peer->gidx = pidx + 1;
                } else {
                        peer->gidx = pidx;
                }
                INIT_WORK(&peer->service, perf_service_work);
        }
        if (perf->gidx == -1)
                perf->gidx = pidx;

        for (pidx = 0; pidx < perf->pcnt; pidx++) {
                ret = perf_setup_peer_mw(&perf->peers[pidx]);
                if (ret)
                        return ret;
        }

        dev_dbg(&perf->ntb->dev, "Global port index %d\n", perf->gidx);

        return 0;
}

static int perf_probe(struct ntb_client *client, struct ntb_dev *ntb)
{
        struct perf_ctx *perf;
        int ret;

        perf = perf_create_data(ntb);
        if (IS_ERR(perf))
                return PTR_ERR(perf);

        ret = perf_init_peers(perf);
        if (ret)
                return ret;

        perf_init_threads(perf);

        ret = perf_init_service(perf);
        if (ret)
                return ret;

        ret = perf_enable_service(perf);
        if (ret)
                return ret;

        perf_setup_dbgfs(perf);

        return 0;
}

static void perf_remove(struct ntb_client *client, struct ntb_dev *ntb)
{
        struct perf_ctx *perf = ntb->ctx;

        perf_clear_dbgfs(perf);

        perf_disable_service(perf);

        perf_clear_threads(perf);
}

static struct ntb_client perf_client = {
        .ops = {
                .probe = perf_probe,
                .remove = perf_remove
        }
};

static int __init perf_init(void)
{
        int ret;

        if (chunk_order > MAX_CHUNK_ORDER) {
                chunk_order = MAX_CHUNK_ORDER;
                pr_info("Chunk order reduced to %hhu\n", chunk_order);
        }

        if (total_order < chunk_order) {
                total_order = chunk_order;
                pr_info("Total data order reduced to %hhu\n", total_order);
        }

        perf_wq = alloc_workqueue("perf_wq", WQ_UNBOUND | WQ_SYSFS, 0);
        if (!perf_wq)
                return -ENOMEM;

        if (debugfs_initialized())
                perf_dbgfs_topdir = debugfs_create_dir(KBUILD_MODNAME, NULL);

        ret = ntb_register_client(&perf_client);
        if (ret) {
                debugfs_remove_recursive(perf_dbgfs_topdir);
                destroy_workqueue(perf_wq);
        }

        return ret;
}
module_init(perf_init);

static void __exit perf_exit(void)
{
        ntb_unregister_client(&perf_client);
        debugfs_remove_recursive(perf_dbgfs_topdir);
        destroy_workqueue(perf_wq);
}
module_exit(perf_exit);