drivers/staging/dgrp/dgrp_dpa_ops.c - linux/kernel/git/viro/vfs - Git at Google

 /*
  *
  * 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 <linux/slab.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 *);

 const struct file_operations dgrp_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,
 };

 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 */


 /*
  * 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;

 	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.
 	 */
 	nd = PDE_DATA(inode);
 	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 > 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);
 		strlcpy(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:
 		memset(&vpd, 0, sizeof(vpd));
 		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;
 }

 /**
  * dgrp_dpa() -- send data to the device monitor queue
  * @nd: pointer to a node structure
  * @buf: buffer of data to copy to the monitoring buffer
  * @len: number of bytes to transfer to the buffer
  *
  * Called by the net device routines to send data to the device
  * monitor queue.  If the device monitor buffer is too full to
  * accept the data, it waits until the buffer is ready.
  */
 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);
 }

 /**
  * dgrp_monitor_data() -- builds a DPA data packet
  * @nd: pointer to a node structure
  * @type: type of message to be logged in the DPA buffer
  * @buf: buffer of data to be logged in the DPA buffer
  * @size -- number of bytes in the "buf" buffer
  */
 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);
 }
	/*
	*
	* 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 <linux/slab.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 );

	const struct file_operations dgrp_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,
	};

	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 */


	/*
	* 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;

	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.
	*/
	nd = PDE_DATA(inode);
	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 > 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);
	strlcpy(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:
	memset(&vpd, 0, sizeof(vpd));
	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;
	}

	/**
	* dgrp_dpa() -- send data to the device monitor queue
	* @nd: pointer to a node structure
	* @buf: buffer of data to copy to the monitoring buffer
	* @len: number of bytes to transfer to the buffer
	*
	* Called by the net device routines to send data to the device
	* monitor queue. If the device monitor buffer is too full to
	* accept the data, it waits until the buffer is ready.
	*/
	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);
	}

	/**
	* dgrp_monitor_data() -- builds a DPA data packet
	* @nd: pointer to a node structure
	* @type: type of message to be logged in the DPA buffer
	* @buf: buffer of data to be logged in the DPA buffer
	* @size -- number of bytes in the "buf" buffer
	*/
	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);
	}