/*
 * 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 EMC 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.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *   General Public License for more details.
 *
 *   BSD LICENSE
 *
 *   Copyright (C) 2015 EMC 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.
 *
 * PCIe NTB Debugging Tool Linux driver
 *
 * Contact Information:
 * Allen Hubbe <Allen.Hubbe@emc.com>
 */

/*
 * How to use this tool, by example.
 *
 * Assuming $DBG_DIR is something like:
 * '/sys/kernel/debug/ntb_tool/0000:00:03.0'
 *
 * Eg: check if clearing the doorbell mask generates an interrupt.
 *
 * # Set the doorbell mask
 * root@self# echo 's 1' > $DBG_DIR/mask
 *
 * # Ring the doorbell from the peer
 * root@peer# echo 's 1' > $DBG_DIR/peer_db
 *
 * # Clear the doorbell mask
 * root@self# echo 'c 1' > $DBG_DIR/mask
 *
 * Observe debugging output in dmesg or your console.  You should see a
 * doorbell event triggered by clearing the mask.  If not, this may indicate an
 * issue with the hardware that needs to be worked around in the driver.
 *
 * Eg: read and write scratchpad registers
 *
 * root@peer# echo '0 0x01010101 1 0x7f7f7f7f' > $DBG_DIR/peer_spad
 *
 * root@self# cat $DBG_DIR/spad
 *
 * Observe that spad 0 and 1 have the values set by the peer.
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>

#include <linux/debugfs.h>
#include <linux/dma-mapping.h>
#include <linux/pci.h>
#include <linux/slab.h>

#include <linux/ntb.h>

#define DRIVER_NAME                     "ntb_tool"
#define DRIVER_DESCRIPTION              "PCIe NTB Debugging Tool"

#define DRIVER_LICENSE                  "Dual BSD/GPL"
#define DRIVER_VERSION                  "1.0"
#define DRIVER_RELDATE                  "22 April 2015"
#define DRIVER_AUTHOR                   "Allen Hubbe <Allen.Hubbe@emc.com>"

MODULE_LICENSE(DRIVER_LICENSE);
MODULE_VERSION(DRIVER_VERSION);
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESCRIPTION);

static struct dentry *tool_dbgfs;

struct tool_ctx {
        struct ntb_dev *ntb;
        struct dentry *dbgfs;
};

#define SPAD_FNAME_SIZE 0x10
#define INT_PTR(x) ((void *)(unsigned long)x)
#define PTR_INT(x) ((int)(unsigned long)x)

#define TOOL_FOPS_RDWR(__name, __read, __write) \
        const struct file_operations __name = { \
                .owner = THIS_MODULE,           \
                .open = simple_open,            \
                .read = __read,                 \
                .write = __write,               \
        }

static void tool_link_event(void *ctx)
{
        struct tool_ctx *tc = ctx;
        enum ntb_speed speed;
        enum ntb_width width;
        int up;

        up = ntb_link_is_up(tc->ntb, &speed, &width);

        dev_dbg(&tc->ntb->dev, "link is %s speed %d width %d\n",
                up ? "up" : "down", speed, width);
}

static void tool_db_event(void *ctx, int vec)
{
        struct tool_ctx *tc = ctx;
        u64 db_bits, db_mask;

        db_mask = ntb_db_vector_mask(tc->ntb, vec);
        db_bits = ntb_db_read(tc->ntb);

        dev_dbg(&tc->ntb->dev, "doorbell vec %d mask %#llx bits %#llx\n",
                vec, db_mask, db_bits);
}

static const struct ntb_ctx_ops tool_ops = {
        .link_event = tool_link_event,
        .db_event = tool_db_event,
};

static ssize_t tool_dbfn_read(struct tool_ctx *tc, char __user *ubuf,
                              size_t size, loff_t *offp,
                              u64 (*db_read_fn)(struct ntb_dev *))
{
        size_t buf_size;
        char *buf;
        ssize_t pos, rc;

        if (!db_read_fn)
                return -EINVAL;

        buf_size = min_t(size_t, size, 0x20);

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

        pos = scnprintf(buf, buf_size, "%#llx\n",
                        db_read_fn(tc->ntb));

        rc = simple_read_from_buffer(ubuf, size, offp, buf, pos);

        kfree(buf);

        return rc;
}

static ssize_t tool_dbfn_write(struct tool_ctx *tc,
                               const char __user *ubuf,
                               size_t size, loff_t *offp,
                               int (*db_set_fn)(struct ntb_dev *, u64),
                               int (*db_clear_fn)(struct ntb_dev *, u64))
{
        u64 db_bits;
        char *buf, cmd;
        ssize_t rc;
        int n;

        buf = kmalloc(size + 1, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        rc = simple_write_to_buffer(buf, size, offp, ubuf, size);
        if (rc < 0) {
                kfree(buf);
                return rc;
        }

        buf[size] = 0;

        n = sscanf(buf, "%c %lli", &cmd, &db_bits);

        kfree(buf);

        if (n != 2) {
                rc = -EINVAL;
        } else if (cmd == 's') {
                if (!db_set_fn)
                        rc = -EINVAL;
                else
                        rc = db_set_fn(tc->ntb, db_bits);
        } else if (cmd == 'c') {
                if (!db_clear_fn)
                        rc = -EINVAL;
                else
                        rc = db_clear_fn(tc->ntb, db_bits);
        } else {
                rc = -EINVAL;
        }

        return rc ? : size;
}

static ssize_t tool_spadfn_read(struct tool_ctx *tc, char __user *ubuf,
                                size_t size, loff_t *offp,
                                u32 (*spad_read_fn)(struct ntb_dev *, int))
{
        size_t buf_size;
        char *buf;
        ssize_t pos, rc;
        int i, spad_count;

        if (!spad_read_fn)
                return -EINVAL;

        buf_size = min_t(size_t, size, 0x100);

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

        pos = 0;

        spad_count = ntb_spad_count(tc->ntb);
        for (i = 0; i < spad_count; ++i) {
                pos += scnprintf(buf + pos, buf_size - pos, "%d\t%#x\n",
                                 i, spad_read_fn(tc->ntb, i));
        }

        rc = simple_read_from_buffer(ubuf, size, offp, buf, pos);

        kfree(buf);

        return rc;
}

static ssize_t tool_spadfn_write(struct tool_ctx *tc,
                                 const char __user *ubuf,
                                 size_t size, loff_t *offp,
                                 int (*spad_write_fn)(struct ntb_dev *,
                                                      int, u32))
{
        int spad_idx;
        u32 spad_val;
        char *buf;
        int pos, n;
        ssize_t rc;

        if (!spad_write_fn) {
                dev_dbg(&tc->ntb->dev, "no spad write fn\n");
                return -EINVAL;
        }

        buf = kmalloc(size + 1, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        rc = simple_write_to_buffer(buf, size, offp, ubuf, size);
        if (rc < 0) {
                kfree(buf);
                return rc;
        }

        buf[size] = 0;

        n = sscanf(buf, "%d %i%n", &spad_idx, &spad_val, &pos);
        while (n == 2) {
                rc = spad_write_fn(tc->ntb, spad_idx, spad_val);
                if (rc)
                        break;

                n = sscanf(buf + pos, "%d %i%n", &spad_idx, &spad_val, &pos);
        }

        if (n < 0)
                rc = n;

        kfree(buf);

        return rc ? : size;
}

static ssize_t tool_db_read(struct file *filep, char __user *ubuf,
                            size_t size, loff_t *offp)
{
        struct tool_ctx *tc = filep->private_data;

        return tool_dbfn_read(tc, ubuf, size, offp,
                              tc->ntb->ops->db_read);
}

static ssize_t tool_db_write(struct file *filep, const char __user *ubuf,
                             size_t size, loff_t *offp)
{
        struct tool_ctx *tc = filep->private_data;

        return tool_dbfn_write(tc, ubuf, size, offp,
                               tc->ntb->ops->db_set,
                               tc->ntb->ops->db_clear);
}

static TOOL_FOPS_RDWR(tool_db_fops,
                      tool_db_read,
                      tool_db_write);

static ssize_t tool_mask_read(struct file *filep, char __user *ubuf,
                              size_t size, loff_t *offp)
{
        struct tool_ctx *tc = filep->private_data;

        return tool_dbfn_read(tc, ubuf, size, offp,
                              tc->ntb->ops->db_read_mask);
}

static ssize_t tool_mask_write(struct file *filep, const char __user *ubuf,
                               size_t size, loff_t *offp)
{
        struct tool_ctx *tc = filep->private_data;

        return tool_dbfn_write(tc, ubuf, size, offp,
                               tc->ntb->ops->db_set_mask,
                               tc->ntb->ops->db_clear_mask);
}

static TOOL_FOPS_RDWR(tool_mask_fops,
                      tool_mask_read,
                      tool_mask_write);

static ssize_t tool_peer_db_read(struct file *filep, char __user *ubuf,
                                 size_t size, loff_t *offp)
{
        struct tool_ctx *tc = filep->private_data;

        return tool_dbfn_read(tc, ubuf, size, offp,
                              tc->ntb->ops->peer_db_read);
}

static ssize_t tool_peer_db_write(struct file *filep, const char __user *ubuf,
                                  size_t size, loff_t *offp)
{
        struct tool_ctx *tc = filep->private_data;

        return tool_dbfn_write(tc, ubuf, size, offp,
                               tc->ntb->ops->peer_db_set,
                               tc->ntb->ops->peer_db_clear);
}

static TOOL_FOPS_RDWR(tool_peer_db_fops,
                      tool_peer_db_read,
                      tool_peer_db_write);

static ssize_t tool_peer_mask_read(struct file *filep, char __user *ubuf,
                                   size_t size, loff_t *offp)
{
        struct tool_ctx *tc = filep->private_data;

        return tool_dbfn_read(tc, ubuf, size, offp,
                              tc->ntb->ops->peer_db_read_mask);
}

static ssize_t tool_peer_mask_write(struct file *filep, const char __user *ubuf,
                                    size_t size, loff_t *offp)
{
        struct tool_ctx *tc = filep->private_data;

        return tool_dbfn_write(tc, ubuf, size, offp,
                               tc->ntb->ops->peer_db_set_mask,
                               tc->ntb->ops->peer_db_clear_mask);
}

static TOOL_FOPS_RDWR(tool_peer_mask_fops,
                      tool_peer_mask_read,
                      tool_peer_mask_write);

static ssize_t tool_spad_read(struct file *filep, char __user *ubuf,
                              size_t size, loff_t *offp)
{
        struct tool_ctx *tc = filep->private_data;

        return tool_spadfn_read(tc, ubuf, size, offp,
                                tc->ntb->ops->spad_read);
}

static ssize_t tool_spad_write(struct file *filep, const char __user *ubuf,
                               size_t size, loff_t *offp)
{
        struct tool_ctx *tc = filep->private_data;

        return tool_spadfn_write(tc, ubuf, size, offp,
                                 tc->ntb->ops->spad_write);
}

static TOOL_FOPS_RDWR(tool_spad_fops,
                      tool_spad_read,
                      tool_spad_write);

static ssize_t tool_peer_spad_read(struct file *filep, char __user *ubuf,
                                   size_t size, loff_t *offp)
{
        struct tool_ctx *tc = filep->private_data;

        return tool_spadfn_read(tc, ubuf, size, offp,
                                tc->ntb->ops->peer_spad_read);
}

static ssize_t tool_peer_spad_write(struct file *filep, const char __user *ubuf,
                                    size_t size, loff_t *offp)
{
        struct tool_ctx *tc = filep->private_data;

        return tool_spadfn_write(tc, ubuf, size, offp,
                                 tc->ntb->ops->peer_spad_write);
}

static TOOL_FOPS_RDWR(tool_peer_spad_fops,
                      tool_peer_spad_read,
                      tool_peer_spad_write);

static void tool_setup_dbgfs(struct tool_ctx *tc)
{
        /* This modules is useless without dbgfs... */
        if (!tool_dbgfs) {
                tc->dbgfs = NULL;
                return;
        }

        tc->dbgfs = debugfs_create_dir(dev_name(&tc->ntb->dev),
                                       tool_dbgfs);
        if (!tc->dbgfs)
                return;

        debugfs_create_file("db", S_IRUSR | S_IWUSR, tc->dbgfs,
                            tc, &tool_db_fops);

        debugfs_create_file("mask", S_IRUSR | S_IWUSR, tc->dbgfs,
                            tc, &tool_mask_fops);

        debugfs_create_file("peer_db", S_IRUSR | S_IWUSR, tc->dbgfs,
                            tc, &tool_peer_db_fops);

        debugfs_create_file("peer_mask", S_IRUSR | S_IWUSR, tc->dbgfs,
                            tc, &tool_peer_mask_fops);

        debugfs_create_file("spad", S_IRUSR | S_IWUSR, tc->dbgfs,
                            tc, &tool_spad_fops);

        debugfs_create_file("peer_spad", S_IRUSR | S_IWUSR, tc->dbgfs,
                            tc, &tool_peer_spad_fops);
}

static int tool_probe(struct ntb_client *self, struct ntb_dev *ntb)
{
        struct tool_ctx *tc;
        int rc;

        if (ntb_db_is_unsafe(ntb))
                dev_dbg(&ntb->dev, "doorbell is unsafe\n");

        if (ntb_spad_is_unsafe(ntb))
                dev_dbg(&ntb->dev, "scratchpad is unsafe\n");

        tc = kmalloc(sizeof(*tc), GFP_KERNEL);
        if (!tc) {
                rc = -ENOMEM;
                goto err_tc;
        }

        tc->ntb = ntb;

        tool_setup_dbgfs(tc);

        rc = ntb_set_ctx(ntb, tc, &tool_ops);
        if (rc)
                goto err_ctx;

        ntb_link_enable(ntb, NTB_SPEED_AUTO, NTB_WIDTH_AUTO);
        ntb_link_event(ntb);

        return 0;

err_ctx:
        debugfs_remove_recursive(tc->dbgfs);
        kfree(tc);
err_tc:
        return rc;
}

static void tool_remove(struct ntb_client *self, struct ntb_dev *ntb)
{
        struct tool_ctx *tc = ntb->ctx;

        ntb_clear_ctx(ntb);
        ntb_link_disable(ntb);

        debugfs_remove_recursive(tc->dbgfs);
        kfree(tc);
}

static struct ntb_client tool_client = {
        .ops = {
                .probe = tool_probe,
                .remove = tool_remove,
        },
};

static int __init tool_init(void)
{
        int rc;

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

        rc = ntb_register_client(&tool_client);
        if (rc)
                goto err_client;

        return 0;

err_client:
        debugfs_remove_recursive(tool_dbgfs);
        return rc;
}
module_init(tool_init);

static void __exit tool_exit(void)
{
        ntb_unregister_client(&tool_client);
        debugfs_remove_recursive(tool_dbgfs);
}
module_exit(tool_exit);