dgrp_dpa_ops.c

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/*
 *
 * Copyright 1999 Digi International (www.digi.com)
 *     James Puzzo <jamesp at digi dot com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY, EXPRESS OR IMPLIED; without even the
 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE.  See the GNU General Public License for more details.
 *
 */

/*
 *
 *  Filename:
 *
 *     dgrp_dpa_ops.c
 *
 *  Description:
 *
 *     Handle the file operations required for the "dpa" devices.
 *     Includes those functions required to register the "dpa" devices
 *     in "/proc".
 *
 *  Author:
 *
 *     James A. Puzzo
 *
 */

#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/tty.h>
#include <linux/poll.h>
#include <linux/cred.h>
#include <linux/sched.h>
#include <linux/ratelimit.h>
#include <asm/unaligned.h>

#include "dgrp_common.h"

/* File operation declarations */
static int dgrp_dpa_open(struct inode *, struct file *);
static int dgrp_dpa_release(struct inode *, struct file *);
static ssize_t dgrp_dpa_read(struct file *, char __user *, size_t, loff_t *);
static long dgrp_dpa_ioctl(struct file *file, unsigned int cmd,
               unsigned long arg);
static unsigned int dgrp_dpa_select(struct file *, struct poll_table_struct *);

static const struct file_operations dpa_ops = {
    .owner   =  THIS_MODULE,
    .read    =  dgrp_dpa_read,
    .poll    =  dgrp_dpa_select,
    .unlocked_ioctl =  dgrp_dpa_ioctl,
    .open    =  dgrp_dpa_open,
    .release =  dgrp_dpa_release,
};

static struct inode_operations dpa_inode_ops = {
    .permission = dgrp_inode_permission
};



struct digi_node {
    uint    nd_state;       /* Node state: 1 = up, 0 = down. */
    uint    nd_chan_count;      /* Number of channels found */
    uint    nd_tx_byte;     /* Tx data count */
    uint    nd_rx_byte;     /* RX data count */
    u8  nd_ps_desc[MAX_DESC_LEN]; /* Description from PS */
};

#define DIGI_GETNODE      (('d'<<8) | 249)  /* get board info */


struct digi_chan {
    uint    ch_port;    /* Port number to get info on */
    uint    ch_open;    /* 1 if open, 0 if not */
    uint    ch_txcount; /* TX data count  */
    uint    ch_rxcount; /* RX data count  */
    uint    ch_s_brate; /* Realport BRATE */
    uint    ch_s_estat; /* Realport ELAST */
    uint    ch_s_cflag; /* Realport CFLAG */
    uint    ch_s_iflag; /* Realport IFLAG */
    uint    ch_s_oflag; /* Realport OFLAG */
    uint    ch_s_xflag; /* Realport XFLAG */
    uint    ch_s_mstat; /* Realport MLAST */
};

#define DIGI_GETCHAN      (('d'<<8) | 248)  /* get channel info */


struct digi_vpd {
    int vpd_len;
    char vpd_data[VPDSIZE];
};

#define DIGI_GETVPD       (('d'<<8) | 246)  /* get VPD info */


struct digi_debug {
    int onoff;
    int port;
};

#define DIGI_SETDEBUG      (('d'<<8) | 247) /* set debug info */


void dgrp_register_dpa_hook(struct proc_dir_entry *de)
{
    struct nd_struct *node = de->data;

    de->proc_iops = &dpa_inode_ops;
    de->proc_fops = &dpa_ops;

    node->nd_dpa_de = de;
    spin_lock_init(&node->nd_dpa_lock);
}

/*
 * dgrp_dpa_open -- open the DPA device for a particular PortServer
 */
static int dgrp_dpa_open(struct inode *inode, struct file *file)
{
    struct nd_struct *nd;
    int rtn = 0;

    struct proc_dir_entry *de;

    rtn = try_module_get(THIS_MODULE);
    if (!rtn)
        return -ENXIO;

    rtn = 0;

    if (!capable(CAP_SYS_ADMIN)) {
        rtn = -EPERM;
        goto done;
    }

    /*
     *  Make sure that the "private_data" field hasn't already been used.
     */
    if (file->private_data) {
        rtn = -EINVAL;
        goto done;
    }

    /*
     *  Get the node pointer, and fail if it doesn't exist.
     */
    de = PDE(inode);
    if (!de) {
        rtn = -ENXIO;
        goto done;
    }
    nd = (struct nd_struct *)de->data;
    if (!nd) {
        rtn = -ENXIO;
        goto done;
    }

    file->private_data = (void *) nd;

    /*
     * Allocate the DPA buffer.
     */

    if (nd->nd_dpa_buf) {
        rtn = -EBUSY;
    } else {
        nd->nd_dpa_buf = kmalloc(DPA_MAX, GFP_KERNEL);

        if (!nd->nd_dpa_buf) {
            rtn = -ENOMEM;
        } else {
            nd->nd_dpa_out = 0;
            nd->nd_dpa_in = 0;
            nd->nd_dpa_lbolt = jiffies;
        }
    }

done:

    if (rtn)
        module_put(THIS_MODULE);
    return rtn;
}

/*
 * dgrp_dpa_release -- close the DPA device for a particular PortServer
 */
static int dgrp_dpa_release(struct inode *inode, struct file *file)
{
    struct nd_struct *nd;
    u8 *buf;
    unsigned long lock_flags;

    /*
     *  Get the node pointer, and quit if it doesn't exist.
     */
    nd = (struct nd_struct *)(file->private_data);
    if (!nd)
        goto done;

    /*
     *  Free the dpa buffer.
     */

    spin_lock_irqsave(&nd->nd_dpa_lock, lock_flags);

    buf = nd->nd_dpa_buf;

    nd->nd_dpa_buf = NULL;
    nd->nd_dpa_out = nd->nd_dpa_in;

    /*
     *  Wakeup any thread waiting for buffer space.
     */

    if (nd->nd_dpa_flag & DPA_WAIT_SPACE) {
        nd->nd_dpa_flag &= ~DPA_WAIT_SPACE;
        wake_up_interruptible(&nd->nd_dpa_wqueue);
    }

    spin_unlock_irqrestore(&nd->nd_dpa_lock, lock_flags);

    kfree(buf);

done:
    module_put(THIS_MODULE);
    file->private_data = NULL;
    return 0;
}

/*
 * dgrp_dpa_read
 *
 * Copy data from the monitoring buffer to the user, freeing space
 * in the monitoring buffer for more messages
 */
static ssize_t dgrp_dpa_read(struct file *file, char __user *buf, size_t count,
                 loff_t *ppos)
{
    struct nd_struct *nd;
    int n;
    int r;
    int offset = 0;
    int res = 0;
    ssize_t rtn;
    unsigned long lock_flags;

    /*
     *  Get the node pointer, and quit if it doesn't exist.
     */
    nd = (struct nd_struct *)(file->private_data);
    if (!nd)
        return -ENXIO;

    /*
     *  Wait for some data to appear in the buffer.
     */

    spin_lock_irqsave(&nd->nd_dpa_lock, lock_flags);

    for (;;) {
        n = (nd->nd_dpa_in - nd->nd_dpa_out) & DPA_MASK;

        if (n != 0)
            break;

        nd->nd_dpa_flag |= DPA_WAIT_DATA;

        spin_unlock_irqrestore(&nd->nd_dpa_lock, lock_flags);

        /*
         * Go to sleep waiting until the condition becomes true.
         */
        rtn = wait_event_interruptible(nd->nd_dpa_wqueue,
            ((nd->nd_dpa_flag & DPA_WAIT_DATA) == 0));

        if (rtn)
            return rtn;

        spin_lock_irqsave(&nd->nd_dpa_lock, lock_flags);
    }

    /*
     *  Read whatever is there.
     */

    if (n > count)
        n = count;

    res = n;

    r = DPA_MAX - nd->nd_dpa_out;

    if (r <= n) {

        spin_unlock_irqrestore(&nd->nd_dpa_lock, lock_flags);
        rtn = copy_to_user((void __user *)buf,
                   nd->nd_dpa_buf + nd->nd_dpa_out, r);
        spin_lock_irqsave(&nd->nd_dpa_lock, lock_flags);

        if (rtn) {
            rtn = -EFAULT;
            goto done;
        }

        nd->nd_dpa_out = 0;
        n -= r;
        offset = r;
    }

    spin_unlock_irqrestore(&nd->nd_dpa_lock, lock_flags);
    rtn = copy_to_user((void __user *)buf + offset,
               nd->nd_dpa_buf + nd->nd_dpa_out, n);
    spin_lock_irqsave(&nd->nd_dpa_lock, lock_flags);

    if (rtn) {
        rtn = -EFAULT;
        goto done;
    }

    nd->nd_dpa_out += n;

    *ppos += res;

    rtn = res;

    /*
     *  Wakeup any thread waiting for buffer space.
     */

    n = (nd->nd_dpa_in - nd->nd_dpa_out) & DPA_MASK;

    if (nd->nd_dpa_flag & DPA_WAIT_SPACE &&
        (DPA_MAX - n) > DPA_HIGH_WATER) {
        nd->nd_dpa_flag &= ~DPA_WAIT_SPACE;
        wake_up_interruptible(&nd->nd_dpa_wqueue);
    }

 done:
    spin_unlock_irqrestore(&nd->nd_dpa_lock, lock_flags);
    return rtn;
}

static unsigned int dgrp_dpa_select(struct file *file,
                    struct poll_table_struct *table)
{
    unsigned int retval = 0;
    struct nd_struct *nd = file->private_data;

    if (nd->nd_dpa_out != nd->nd_dpa_in)
        retval |= POLLIN | POLLRDNORM; /* Conditionally readable */

    retval |= POLLOUT | POLLWRNORM;        /* Always writeable */

    return retval;
}

static long dgrp_dpa_ioctl(struct file *file, unsigned int cmd,
               unsigned long arg)
{

    struct nd_struct  *nd;
    struct digi_chan getchan;
    struct digi_node getnode;
    struct ch_struct *ch;
    struct digi_debug setdebug;
    struct digi_vpd vpd;
    unsigned int port;
    void __user *uarg = (void __user *) arg;

    nd = file->private_data;

    switch (cmd) {
    case DIGI_GETCHAN:
        if (copy_from_user(&getchan, uarg, sizeof(struct digi_chan)))
            return -EFAULT;

        port = getchan.ch_port;

        if (port < 0 || port > nd->nd_chan_count)
            return -EINVAL;

        ch = nd->nd_chan + port;

        getchan.ch_open = (ch->ch_open_count > 0) ? 1 : 0;
        getchan.ch_txcount = ch->ch_txcount;
        getchan.ch_rxcount = ch->ch_rxcount;
        getchan.ch_s_brate = ch->ch_s_brate;
        getchan.ch_s_estat = ch->ch_s_elast;
        getchan.ch_s_cflag = ch->ch_s_cflag;
        getchan.ch_s_iflag = ch->ch_s_iflag;
        getchan.ch_s_oflag = ch->ch_s_oflag;
        getchan.ch_s_xflag = ch->ch_s_xflag;
        getchan.ch_s_mstat = ch->ch_s_mlast;

        if (copy_to_user(uarg, &getchan, sizeof(struct digi_chan)))
            return -EFAULT;
        break;


    case DIGI_GETNODE:
        getnode.nd_state = (nd->nd_state & NS_READY) ? 1 : 0;
        getnode.nd_chan_count = nd->nd_chan_count;
        getnode.nd_tx_byte = nd->nd_tx_byte;
        getnode.nd_rx_byte = nd->nd_rx_byte;

        memset(&getnode.nd_ps_desc, 0, MAX_DESC_LEN);
        strncpy(getnode.nd_ps_desc, nd->nd_ps_desc, MAX_DESC_LEN);

        if (copy_to_user(uarg, &getnode, sizeof(struct digi_node)))
            return -EFAULT;
        break;


    case DIGI_SETDEBUG:
        if (copy_from_user(&setdebug, uarg, sizeof(struct digi_debug)))
            return -EFAULT;

        nd->nd_dpa_debug = setdebug.onoff;
        nd->nd_dpa_port = setdebug.port;
        break;


    case DIGI_GETVPD:
        if (nd->nd_vpd_len > 0) {
            vpd.vpd_len = nd->nd_vpd_len;
            memcpy(&vpd.vpd_data, &nd->nd_vpd, nd->nd_vpd_len);
        } else {
            vpd.vpd_len = 0;
        }

        if (copy_to_user(uarg, &vpd, sizeof(struct digi_vpd)))
            return -EFAULT;
        break;
    }

    return 0;
}

static void dgrp_dpa(struct nd_struct *nd, u8 *buf, int nbuf)
{
    int n;
    int r;
    unsigned long lock_flags;

    /*
     *  Grab DPA lock.
     */
    spin_lock_irqsave(&nd->nd_dpa_lock, lock_flags);

    /*
     *  Loop while data remains.
     */
    while (nbuf > 0 && nd->nd_dpa_buf != NULL) {

        n = (nd->nd_dpa_out - nd->nd_dpa_in - 1) & DPA_MASK;

        /*
         * Enforce flow control on the DPA device.
         */
        if (n < (DPA_MAX - DPA_HIGH_WATER))
            nd->nd_dpa_flag |= DPA_WAIT_SPACE;

        /*
         * This should never happen, as the flow control above
         * should have stopped things before they got to this point.
         */
        if (n == 0) {
            spin_unlock_irqrestore(&nd->nd_dpa_lock, lock_flags);
            return;
        }

        /*
         * Copy as much data as will fit.
         */

        if (n > nbuf)
            n = nbuf;

        r = DPA_MAX - nd->nd_dpa_in;

        if (r <= n) {
            memcpy(nd->nd_dpa_buf + nd->nd_dpa_in, buf, r);

            n -= r;

            nd->nd_dpa_in = 0;

            buf += r;
            nbuf -= r;
        }

        memcpy(nd->nd_dpa_buf + nd->nd_dpa_in, buf, n);

        nd->nd_dpa_in += n;

        buf += n;
        nbuf -= n;

        if (nd->nd_dpa_in >= DPA_MAX)
            pr_info_ratelimited("%s - nd->nd_dpa_in (%i) >= DPA_MAX\n",
                        __func__, nd->nd_dpa_in);

        /*
         *  Wakeup any thread waiting for data
         */
        if (nd->nd_dpa_flag & DPA_WAIT_DATA) {
            nd->nd_dpa_flag &= ~DPA_WAIT_DATA;
            wake_up_interruptible(&nd->nd_dpa_wqueue);
        }
    }

    /*
     *  Release the DPA lock.
     */
    spin_unlock_irqrestore(&nd->nd_dpa_lock, lock_flags);
}

void dgrp_dpa_data(struct nd_struct *nd, int type, u8 *buf, int size)
{
    u8 header[5];

    header[0] = type;

    put_unaligned_be32(size, header + 1);

    dgrp_dpa(nd, header, sizeof(header));
    dgrp_dpa(nd, buf, size);
}