/*
 * Copyright (c) 2012 Intel Corporation. All rights reserved.
 * Copyright (c) 2006 - 2012 QLogic Corporation. All rights reserved.
 * Copyright (c) 2006 PathScale, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     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
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/fs_context.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/init.h>
#include <linux/namei.h>

#include "qib.h"

#define QIBFS_MAGIC 0x726a77

static struct super_block *qib_super;

#define private2dd(file) (file_inode(file)->i_private)

static int qibfs_mknod(struct inode *dir, struct dentry *dentry,
                       umode_t mode, const struct file_operations *fops,
                       void *data)
{
        int error;
        struct inode *inode = new_inode(dir->i_sb);

        if (!inode) {
                error = -EPERM;
                goto bail;
        }

        inode->i_ino = get_next_ino();
        inode->i_mode = mode;
        inode->i_uid = GLOBAL_ROOT_UID;
        inode->i_gid = GLOBAL_ROOT_GID;
        inode->i_blocks = 0;
        inode->i_atime = current_time(inode);
        inode->i_mtime = inode->i_atime;
        inode->i_ctime = inode->i_atime;
        inode->i_private = data;
        if (S_ISDIR(mode)) {
                inode->i_op = &simple_dir_inode_operations;
                inc_nlink(inode);
                inc_nlink(dir);
        }

        inode->i_fop = fops;

        d_instantiate(dentry, inode);
        error = 0;

bail:
        return error;
}

static int create_file(const char *name, umode_t mode,
                       struct dentry *parent, struct dentry **dentry,
                       const struct file_operations *fops, void *data)
{
        int error;

        inode_lock(d_inode(parent));
        *dentry = lookup_one_len(name, parent, strlen(name));
        if (!IS_ERR(*dentry))
                error = qibfs_mknod(d_inode(parent), *dentry,
                                    mode, fops, data);
        else
                error = PTR_ERR(*dentry);
        inode_unlock(d_inode(parent));

        return error;
}

static ssize_t driver_stats_read(struct file *file, char __user *buf,
                                 size_t count, loff_t *ppos)
{
        qib_stats.sps_ints = qib_sps_ints();
        return simple_read_from_buffer(buf, count, ppos, &qib_stats,
                                       sizeof(qib_stats));
}

/*
 * driver stats field names, one line per stat, single string.  Used by
 * programs like ipathstats to print the stats in a way which works for
 * different versions of drivers, without changing program source.
 * if qlogic_ib_stats changes, this needs to change.  Names need to be
 * 12 chars or less (w/o newline), for proper display by ipathstats utility.
 */
static const char qib_statnames[] =
        "KernIntr\n"
        "ErrorIntr\n"
        "Tx_Errs\n"
        "Rcv_Errs\n"
        "H/W_Errs\n"
        "NoPIOBufs\n"
        "CtxtsOpen\n"
        "RcvLen_Errs\n"
        "EgrBufFull\n"
        "EgrHdrFull\n"
        ;

static ssize_t driver_names_read(struct file *file, char __user *buf,
                                 size_t count, loff_t *ppos)
{
        return simple_read_from_buffer(buf, count, ppos, qib_statnames,
                sizeof(qib_statnames) - 1); /* no null */
}

static const struct file_operations driver_ops[] = {
        { .read = driver_stats_read, .llseek = generic_file_llseek, },
        { .read = driver_names_read, .llseek = generic_file_llseek, },
};

/* read the per-device counters */
static ssize_t dev_counters_read(struct file *file, char __user *buf,
                                 size_t count, loff_t *ppos)
{
        u64 *counters;
        size_t avail;
        struct qib_devdata *dd = private2dd(file);

        avail = dd->f_read_cntrs(dd, *ppos, NULL, &counters);
        return simple_read_from_buffer(buf, count, ppos, counters, avail);
}

/* read the per-device counters */
static ssize_t dev_names_read(struct file *file, char __user *buf,
                              size_t count, loff_t *ppos)
{
        char *names;
        size_t avail;
        struct qib_devdata *dd = private2dd(file);

        avail = dd->f_read_cntrs(dd, *ppos, &names, NULL);
        return simple_read_from_buffer(buf, count, ppos, names, avail);
}

static const struct file_operations cntr_ops[] = {
        { .read = dev_counters_read, .llseek = generic_file_llseek, },
        { .read = dev_names_read, .llseek = generic_file_llseek, },
};

/*
 * Could use file_inode(file)->i_ino to figure out which file,
 * instead of separate routine for each, but for now, this works...
 */

/* read the per-port names (same for each port) */
static ssize_t portnames_read(struct file *file, char __user *buf,
                              size_t count, loff_t *ppos)
{
        char *names;
        size_t avail;
        struct qib_devdata *dd = private2dd(file);

        avail = dd->f_read_portcntrs(dd, *ppos, 0, &names, NULL);
        return simple_read_from_buffer(buf, count, ppos, names, avail);
}

/* read the per-port counters for port 1 (pidx 0) */
static ssize_t portcntrs_1_read(struct file *file, char __user *buf,
                                size_t count, loff_t *ppos)
{
        u64 *counters;
        size_t avail;
        struct qib_devdata *dd = private2dd(file);

        avail = dd->f_read_portcntrs(dd, *ppos, 0, NULL, &counters);
        return simple_read_from_buffer(buf, count, ppos, counters, avail);
}

/* read the per-port counters for port 2 (pidx 1) */
static ssize_t portcntrs_2_read(struct file *file, char __user *buf,
                                size_t count, loff_t *ppos)
{
        u64 *counters;
        size_t avail;
        struct qib_devdata *dd = private2dd(file);

        avail = dd->f_read_portcntrs(dd, *ppos, 1, NULL, &counters);
        return simple_read_from_buffer(buf, count, ppos, counters, avail);
}

static const struct file_operations portcntr_ops[] = {
        { .read = portnames_read, .llseek = generic_file_llseek, },
        { .read = portcntrs_1_read, .llseek = generic_file_llseek, },
        { .read = portcntrs_2_read, .llseek = generic_file_llseek, },
};

/*
 * read the per-port QSFP data for port 1 (pidx 0)
 */
static ssize_t qsfp_1_read(struct file *file, char __user *buf,
                           size_t count, loff_t *ppos)
{
        struct qib_devdata *dd = private2dd(file);
        char *tmp;
        int ret;

        tmp = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (!tmp)
                return -ENOMEM;

        ret = qib_qsfp_dump(dd->pport, tmp, PAGE_SIZE);
        if (ret > 0)
                ret = simple_read_from_buffer(buf, count, ppos, tmp, ret);
        kfree(tmp);
        return ret;
}

/*
 * read the per-port QSFP data for port 2 (pidx 1)
 */
static ssize_t qsfp_2_read(struct file *file, char __user *buf,
                           size_t count, loff_t *ppos)
{
        struct qib_devdata *dd = private2dd(file);
        char *tmp;
        int ret;

        if (dd->num_pports < 2)
                return -ENODEV;

        tmp = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (!tmp)
                return -ENOMEM;

        ret = qib_qsfp_dump(dd->pport + 1, tmp, PAGE_SIZE);
        if (ret > 0)
                ret = simple_read_from_buffer(buf, count, ppos, tmp, ret);
        kfree(tmp);
        return ret;
}

static const struct file_operations qsfp_ops[] = {
        { .read = qsfp_1_read, .llseek = generic_file_llseek, },
        { .read = qsfp_2_read, .llseek = generic_file_llseek, },
};

static ssize_t flash_read(struct file *file, char __user *buf,
                          size_t count, loff_t *ppos)
{
        struct qib_devdata *dd;
        ssize_t ret;
        loff_t pos;
        char *tmp;

        pos = *ppos;

        if (pos < 0) {
                ret = -EINVAL;
                goto bail;
        }

        if (pos >= sizeof(struct qib_flash)) {
                ret = 0;
                goto bail;
        }

        if (count > sizeof(struct qib_flash) - pos)
                count = sizeof(struct qib_flash) - pos;

        tmp = kmalloc(count, GFP_KERNEL);
        if (!tmp) {
                ret = -ENOMEM;
                goto bail;
        }

        dd = private2dd(file);
        if (qib_eeprom_read(dd, pos, tmp, count)) {
                qib_dev_err(dd, "failed to read from flash\n");
                ret = -ENXIO;
                goto bail_tmp;
        }

        if (copy_to_user(buf, tmp, count)) {
                ret = -EFAULT;
                goto bail_tmp;
        }

        *ppos = pos + count;
        ret = count;

bail_tmp:
        kfree(tmp);

bail:
        return ret;
}

static ssize_t flash_write(struct file *file, const char __user *buf,
                           size_t count, loff_t *ppos)
{
        struct qib_devdata *dd;
        ssize_t ret;
        loff_t pos;
        char *tmp;

        pos = *ppos;

        if (pos != 0 || count != sizeof(struct qib_flash))
                return -EINVAL;

        tmp = memdup_user(buf, count);
        if (IS_ERR(tmp))
                return PTR_ERR(tmp);

        dd = private2dd(file);
        if (qib_eeprom_write(dd, pos, tmp, count)) {
                ret = -ENXIO;
                qib_dev_err(dd, "failed to write to flash\n");
                goto bail_tmp;
        }

        *ppos = pos + count;
        ret = count;

bail_tmp:
        kfree(tmp);
        return ret;
}

static const struct file_operations flash_ops = {
        .read = flash_read,
        .write = flash_write,
        .llseek = default_llseek,
};

static int add_cntr_files(struct super_block *sb, struct qib_devdata *dd)
{
        struct dentry *dir, *tmp;
        char unit[10];
        int ret, i;

        /* create the per-unit directory */
        snprintf(unit, sizeof(unit), "%u", dd->unit);
        ret = create_file(unit, S_IFDIR|S_IRUGO|S_IXUGO, sb->s_root, &dir,
                          &simple_dir_operations, dd);
        if (ret) {
                pr_err("create_file(%s) failed: %d\n", unit, ret);
                goto bail;
        }

        /* create the files in the new directory */
        ret = create_file("counters", S_IFREG|S_IRUGO, dir, &tmp,
                          &cntr_ops[0], dd);
        if (ret) {
                pr_err("create_file(%s/counters) failed: %d\n",
                       unit, ret);
                goto bail;
        }
        ret = create_file("counter_names", S_IFREG|S_IRUGO, dir, &tmp,
                          &cntr_ops[1], dd);
        if (ret) {
                pr_err("create_file(%s/counter_names) failed: %d\n",
                       unit, ret);
                goto bail;
        }
        ret = create_file("portcounter_names", S_IFREG|S_IRUGO, dir, &tmp,
                          &portcntr_ops[0], dd);
        if (ret) {
                pr_err("create_file(%s/%s) failed: %d\n",
                       unit, "portcounter_names", ret);
                goto bail;
        }
        for (i = 1; i <= dd->num_pports; i++) {
                char fname[24];

                sprintf(fname, "port%dcounters", i);
                /* create the files in the new directory */
                ret = create_file(fname, S_IFREG|S_IRUGO, dir, &tmp,
                                  &portcntr_ops[i], dd);
                if (ret) {
                        pr_err("create_file(%s/%s) failed: %d\n",
                                unit, fname, ret);
                        goto bail;
                }
                if (!(dd->flags & QIB_HAS_QSFP))
                        continue;
                sprintf(fname, "qsfp%d", i);
                ret = create_file(fname, S_IFREG|S_IRUGO, dir, &tmp,
                                  &qsfp_ops[i - 1], dd);
                if (ret) {
                        pr_err("create_file(%s/%s) failed: %d\n",
                                unit, fname, ret);
                        goto bail;
                }
        }

        ret = create_file("flash", S_IFREG|S_IWUSR|S_IRUGO, dir, &tmp,
                          &flash_ops, dd);
        if (ret)
                pr_err("create_file(%s/flash) failed: %d\n",
                        unit, ret);
bail:
        return ret;
}

static int remove_file(struct dentry *parent, char *name)
{
        struct dentry *tmp;
        int ret;

        tmp = lookup_one_len(name, parent, strlen(name));

        if (IS_ERR(tmp)) {
                ret = PTR_ERR(tmp);
                goto bail;
        }

        spin_lock(&tmp->d_lock);
        if (simple_positive(tmp)) {
                __d_drop(tmp);
                spin_unlock(&tmp->d_lock);
                simple_unlink(d_inode(parent), tmp);
        } else {
                spin_unlock(&tmp->d_lock);
        }
        dput(tmp);

        ret = 0;
bail:
        /*
         * We don't expect clients to care about the return value, but
         * it's there if they need it.
         */
        return ret;
}

static int remove_device_files(struct super_block *sb,
                               struct qib_devdata *dd)
{
        struct dentry *dir, *root;
        char unit[10];
        int ret, i;

        root = dget(sb->s_root);
        inode_lock(d_inode(root));
        snprintf(unit, sizeof(unit), "%u", dd->unit);
        dir = lookup_one_len(unit, root, strlen(unit));

        if (IS_ERR(dir)) {
                ret = PTR_ERR(dir);
                pr_err("Lookup of %s failed\n", unit);
                goto bail;
        }

        inode_lock(d_inode(dir));
        remove_file(dir, "counters");
        remove_file(dir, "counter_names");
        remove_file(dir, "portcounter_names");
        for (i = 0; i < dd->num_pports; i++) {
                char fname[24];

                sprintf(fname, "port%dcounters", i + 1);
                remove_file(dir, fname);
                if (dd->flags & QIB_HAS_QSFP) {
                        sprintf(fname, "qsfp%d", i + 1);
                        remove_file(dir, fname);
                }
        }
        remove_file(dir, "flash");
        inode_unlock(d_inode(dir));
        ret = simple_rmdir(d_inode(root), dir);
        d_drop(dir);
        dput(dir);

bail:
        inode_unlock(d_inode(root));
        dput(root);
        return ret;
}

/*
 * This fills everything in when the fs is mounted, to handle umount/mount
 * after device init.  The direct add_cntr_files() call handles adding
 * them from the init code, when the fs is already mounted.
 */
static int qibfs_fill_super(struct super_block *sb, struct fs_context *fc)
{
        struct qib_devdata *dd;
        unsigned long index;
        int ret;

        static const struct tree_descr files[] = {
                [2] = {"driver_stats", &driver_ops[0], S_IRUGO},
                [3] = {"driver_stats_names", &driver_ops[1], S_IRUGO},
                {""},
        };

        ret = simple_fill_super(sb, QIBFS_MAGIC, files);
        if (ret) {
                pr_err("simple_fill_super failed: %d\n", ret);
                goto bail;
        }

        xa_for_each(&qib_dev_table, index, dd) {
                ret = add_cntr_files(sb, dd);
                if (ret)
                        goto bail;
        }

bail:
        return ret;
}

static int qibfs_get_tree(struct fs_context *fc)
{
        int ret = get_tree_single(fc, qibfs_fill_super);
        if (ret == 0)
                qib_super = fc->root->d_sb;
        return ret;
}

static const struct fs_context_operations qibfs_context_ops = {
        .get_tree       = qibfs_get_tree,
};

static int qibfs_init_fs_context(struct fs_context *fc)
{
        fc->ops = &qibfs_context_ops;
        return 0;
}

static void qibfs_kill_super(struct super_block *s)
{
        kill_litter_super(s);
        qib_super = NULL;
}

int qibfs_add(struct qib_devdata *dd)
{
        int ret;

        /*
         * On first unit initialized, qib_super will not yet exist
         * because nobody has yet tried to mount the filesystem, so
         * we can't consider that to be an error; if an error occurs
         * during the mount, that will get a complaint, so this is OK.
         * add_cntr_files() for all units is done at mount from
         * qibfs_fill_super(), so one way or another, everything works.
         */
        if (qib_super == NULL)
                ret = 0;
        else
                ret = add_cntr_files(qib_super, dd);
        return ret;
}

int qibfs_remove(struct qib_devdata *dd)
{
        int ret = 0;

        if (qib_super)
                ret = remove_device_files(qib_super, dd);

        return ret;
}

static struct file_system_type qibfs_fs_type = {
        .owner =        THIS_MODULE,
        .name =         "ipathfs",
        .init_fs_context = qibfs_init_fs_context,
        .kill_sb =      qibfs_kill_super,
};
MODULE_ALIAS_FS("ipathfs");

int __init qib_init_qibfs(void)
{
        return register_filesystem(&qibfs_fs_type);
}

int __exit qib_exit_qibfs(void)
{
        return unregister_filesystem(&qibfs_fs_type);
}