/*
    comedi/drivers/vmk80xx.c
    Velleman USB Board Low-Level Driver

    Copyright (C) 2009 Manuel Gebele <forensixs@gmx.de>, Germany

    COMEDI - Linux Control and Measurement Device Interface
    Copyright (C) 2000 David A. Schleef <ds@schleef.org>

    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 of the License, or
    (at your option) any later version.

    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.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/
/*
Driver: vmk80xx
Description: Velleman USB Board Low-Level Driver
Devices: K8055/K8061 aka VM110/VM140
Author: Manuel Gebele <forensixs@gmx.de>
Updated: Sun, 10 May 2009 11:14:59 +0200
Status: works

Supports:
 - analog input
 - analog output
 - digital input
 - digital output
 - counter
 - pwm
*/
/*
Changelog:

0.8.81	-3-  code completely rewritten (adjust driver logic)
0.8.81  -2-  full support for K8061
0.8.81  -1-  fix some mistaken among others the number of
	     supported boards and I/O handling

0.7.76  -4-  renamed to vmk80xx
0.7.76  -3-  detect K8061 (only theoretically supported)
0.7.76  -2-  code completely rewritten (adjust driver logic)
0.7.76  -1-  support for digital and counter subdevice
*/

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/errno.h>
#include <linux/input.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/usb.h>
#include <linux/uaccess.h>

#include "../comedidev.h"

MODULE_AUTHOR("Manuel Gebele <forensixs@gmx.de>");
MODULE_DESCRIPTION("Velleman USB Board Low-Level Driver");
MODULE_SUPPORTED_DEVICE("K8055/K8061 aka VM110/VM140");
MODULE_VERSION("0.8.01");
MODULE_LICENSE("GPL");

enum {
	DEVICE_VMK8055,
	DEVICE_VMK8061
};

static const struct usb_device_id vmk80xx_id_table[] = {
	{USB_DEVICE(0x10cf, 0x5500), .driver_info = DEVICE_VMK8055},
	{USB_DEVICE(0x10cf, 0x5501), .driver_info = DEVICE_VMK8055},
	{USB_DEVICE(0x10cf, 0x5502), .driver_info = DEVICE_VMK8055},
	{USB_DEVICE(0x10cf, 0x5503), .driver_info = DEVICE_VMK8055},
	{USB_DEVICE(0x10cf, 0x8061), .driver_info = DEVICE_VMK8061},
	{USB_DEVICE(0x10cf, 0x8062), .driver_info = DEVICE_VMK8061},
	{USB_DEVICE(0x10cf, 0x8063), .driver_info = DEVICE_VMK8061},
	{USB_DEVICE(0x10cf, 0x8064), .driver_info = DEVICE_VMK8061},
	{USB_DEVICE(0x10cf, 0x8065), .driver_info = DEVICE_VMK8061},
	{USB_DEVICE(0x10cf, 0x8066), .driver_info = DEVICE_VMK8061},
	{USB_DEVICE(0x10cf, 0x8067), .driver_info = DEVICE_VMK8061},
	{USB_DEVICE(0x10cf, 0x8068), .driver_info = DEVICE_VMK8061},
	{}			/* terminating entry */
};

MODULE_DEVICE_TABLE(usb, vmk80xx_id_table);

#define VMK8055_DI_REG          0x00
#define VMK8055_DO_REG          0x01
#define VMK8055_AO1_REG         0x02
#define VMK8055_AO2_REG         0x03
#define VMK8055_AI1_REG         0x02
#define VMK8055_AI2_REG         0x03
#define VMK8055_CNT1_REG        0x04
#define VMK8055_CNT2_REG        0x06

#define VMK8061_CH_REG          0x01
#define VMK8061_DI_REG          0x01
#define VMK8061_DO_REG          0x01
#define VMK8061_PWM_REG1        0x01
#define VMK8061_PWM_REG2        0x02
#define VMK8061_CNT_REG         0x02
#define VMK8061_AO_REG          0x02
#define VMK8061_AI_REG1         0x02
#define VMK8061_AI_REG2         0x03

#define VMK8055_CMD_RST         0x00
#define VMK8055_CMD_DEB1_TIME   0x01
#define VMK8055_CMD_DEB2_TIME   0x02
#define VMK8055_CMD_RST_CNT1    0x03
#define VMK8055_CMD_RST_CNT2    0x04
#define VMK8055_CMD_WRT_AD      0x05

#define VMK8061_CMD_RD_AI       0x00
#define VMK8061_CMR_RD_ALL_AI   0x01	/* !non-active! */
#define VMK8061_CMD_SET_AO      0x02
#define VMK8061_CMD_SET_ALL_AO  0x03	/* !non-active! */
#define VMK8061_CMD_OUT_PWM     0x04
#define VMK8061_CMD_RD_DI       0x05
#define VMK8061_CMD_DO          0x06	/* !non-active! */
#define VMK8061_CMD_CLR_DO      0x07
#define VMK8061_CMD_SET_DO      0x08
#define VMK8061_CMD_RD_CNT      0x09	/* TODO: completely pointless? */
#define VMK8061_CMD_RST_CNT     0x0a	/* TODO: completely pointless? */
#define VMK8061_CMD_RD_VERSION  0x0b	/* internal usage */
#define VMK8061_CMD_RD_JMP_STAT 0x0c	/* TODO: not implemented yet */
#define VMK8061_CMD_RD_PWR_STAT 0x0d	/* internal usage */
#define VMK8061_CMD_RD_DO       0x0e
#define VMK8061_CMD_RD_AO       0x0f
#define VMK8061_CMD_RD_PWM      0x10

#define VMK80XX_MAX_BOARDS      COMEDI_NUM_BOARD_MINORS

#define TRANS_OUT_BUSY          1
#define TRANS_IN_BUSY           2
#define TRANS_IN_RUNNING        3

#define IC3_VERSION             (1 << 0)
#define IC6_VERSION             (1 << 1)

#define URB_RCV_FLAG            (1 << 0)
#define URB_SND_FLAG            (1 << 1)

#define CONFIG_VMK80XX_DEBUG
#undef CONFIG_VMK80XX_DEBUG

#ifdef CONFIG_VMK80XX_DEBUG
static int dbgvm = 1;
#else
static int dbgvm;
#endif

#ifdef CONFIG_COMEDI_DEBUG
static int dbgcm = 1;
#else
static int dbgcm;
#endif

#define dbgvm(fmt, arg...)                     \
do {                                           \
	if (dbgvm)                             \
		printk(KERN_DEBUG fmt, ##arg); \
} while (0)

#define dbgcm(fmt, arg...)                     \
do {                                           \
	if (dbgcm)                             \
		printk(KERN_DEBUG fmt, ##arg); \
} while (0)

enum vmk80xx_model {
	VMK8055_MODEL,
	VMK8061_MODEL
};

struct firmware_version {
	unsigned char ic3_vers[32];	/* USB-Controller */
	unsigned char ic6_vers[32];	/* CPU */
};

static const struct comedi_lrange vmk8055_range = {
	1, {UNI_RANGE(5)}
};

static const struct comedi_lrange vmk8061_range = {
	2, {UNI_RANGE(5), UNI_RANGE(10)}
};

struct vmk80xx_board {
	const char *name;
	enum vmk80xx_model model;
	const struct comedi_lrange *range;
	__u8 ai_chans;
	__le16 ai_bits;
	__u8 ao_chans;
	__le16 ao_bits;
	__u8 di_chans;
	__le16 di_bits;
	__u8 do_chans;
	__le16 do_bits;
	__u8 cnt_chans;
	__le16 cnt_bits;
	__u8 pwm_chans;
	__le16 pwm_bits;
};

enum {
	VMK80XX_SUBD_AI,
	VMK80XX_SUBD_AO,
	VMK80XX_SUBD_DI,
	VMK80XX_SUBD_DO,
	VMK80XX_SUBD_CNT,
	VMK80XX_SUBD_PWM,
};

struct vmk80xx_usb {
	struct usb_device *udev;
	struct usb_interface *intf;
	struct usb_endpoint_descriptor *ep_rx;
	struct usb_endpoint_descriptor *ep_tx;
	struct usb_anchor rx_anchor;
	struct usb_anchor tx_anchor;
	struct vmk80xx_board board;
	struct firmware_version fw;
	struct semaphore limit_sem;
	wait_queue_head_t read_wait;
	wait_queue_head_t write_wait;
	unsigned char *usb_rx_buf;
	unsigned char *usb_tx_buf;
	unsigned long flags;
	int probed;
	int attached;
	int count;
};

static struct vmk80xx_usb vmb[VMK80XX_MAX_BOARDS];

static DEFINE_MUTEX(glb_mutex);

static void vmk80xx_tx_callback(struct urb *urb)
{
	struct vmk80xx_usb *dev = urb->context;
	int stat = urb->status;

	dbgvm("vmk80xx: %s\n", __func__);

	if (stat && !(stat == -ENOENT
		      || stat == -ECONNRESET || stat == -ESHUTDOWN))
		dbgcm("comedi#: vmk80xx: %s - nonzero urb status (%d)\n",
		      __func__, stat);

	if (!test_bit(TRANS_OUT_BUSY, &dev->flags))
		return;

	clear_bit(TRANS_OUT_BUSY, &dev->flags);

	wake_up_interruptible(&dev->write_wait);
}

static void vmk80xx_rx_callback(struct urb *urb)
{
	struct vmk80xx_usb *dev = urb->context;
	int stat = urb->status;

	dbgvm("vmk80xx: %s\n", __func__);

	switch (stat) {
	case 0:
		break;
	case -ENOENT:
	case -ECONNRESET:
	case -ESHUTDOWN:
		break;
	default:
		dbgcm("comedi#: vmk80xx: %s - nonzero urb status (%d)\n",
		      __func__, stat);
		goto resubmit;
	}

	goto exit;
resubmit:
	if (test_bit(TRANS_IN_RUNNING, &dev->flags) && dev->intf) {
		usb_anchor_urb(urb, &dev->rx_anchor);

		if (!usb_submit_urb(urb, GFP_KERNEL))
			goto exit;

		err("comedi#: vmk80xx: %s - submit urb failed\n", __func__);

		usb_unanchor_urb(urb);
	}
exit:
	clear_bit(TRANS_IN_BUSY, &dev->flags);

	wake_up_interruptible(&dev->read_wait);
}

static int vmk80xx_check_data_link(struct vmk80xx_usb *dev)
{
	unsigned int tx_pipe, rx_pipe;
	unsigned char tx[1], rx[2];

	dbgvm("vmk80xx: %s\n", __func__);

	tx_pipe = usb_sndbulkpipe(dev->udev, 0x01);
	rx_pipe = usb_rcvbulkpipe(dev->udev, 0x81);

	tx[0] = VMK8061_CMD_RD_PWR_STAT;

	/* Check that IC6 (PIC16F871) is powered and
	 * running and the data link between IC3 and
	 * IC6 is working properly */
	usb_bulk_msg(dev->udev, tx_pipe, tx, 1, NULL, dev->ep_tx->bInterval);
	usb_bulk_msg(dev->udev, rx_pipe, rx, 2, NULL, HZ * 10);

	return (int)rx[1];
}

static void vmk80xx_read_eeprom(struct vmk80xx_usb *dev, int flag)
{
	unsigned int tx_pipe, rx_pipe;
	unsigned char tx[1], rx[64];
	int cnt;

	dbgvm("vmk80xx: %s\n", __func__);

	tx_pipe = usb_sndbulkpipe(dev->udev, 0x01);
	rx_pipe = usb_rcvbulkpipe(dev->udev, 0x81);

	tx[0] = VMK8061_CMD_RD_VERSION;

	/* Read the firmware version info of IC3 and
	 * IC6 from the internal EEPROM of the IC */
	usb_bulk_msg(dev->udev, tx_pipe, tx, 1, NULL, dev->ep_tx->bInterval);
	usb_bulk_msg(dev->udev, rx_pipe, rx, 64, &cnt, HZ * 10);

	rx[cnt] = '\0';

	if (flag & IC3_VERSION)
		strncpy(dev->fw.ic3_vers, rx + 1, 24);
	else			/* IC6_VERSION */
		strncpy(dev->fw.ic6_vers, rx + 25, 24);
}

static int vmk80xx_reset_device(struct vmk80xx_usb *dev)
{
	struct urb *urb;
	unsigned int tx_pipe;
	int ival;
	size_t size;

	dbgvm("vmk80xx: %s\n", __func__);

	urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!urb)
		return -ENOMEM;

	tx_pipe = usb_sndintpipe(dev->udev, 0x01);

	ival = dev->ep_tx->bInterval;
	size = le16_to_cpu(dev->ep_tx->wMaxPacketSize);

	dev->usb_tx_buf[0] = VMK8055_CMD_RST;
	dev->usb_tx_buf[1] = 0x00;
	dev->usb_tx_buf[2] = 0x00;
	dev->usb_tx_buf[3] = 0x00;
	dev->usb_tx_buf[4] = 0x00;
	dev->usb_tx_buf[5] = 0x00;
	dev->usb_tx_buf[6] = 0x00;
	dev->usb_tx_buf[7] = 0x00;

	usb_fill_int_urb(urb, dev->udev, tx_pipe, dev->usb_tx_buf,
			 size, vmk80xx_tx_callback, dev, ival);

	usb_anchor_urb(urb, &dev->tx_anchor);

	return usb_submit_urb(urb, GFP_KERNEL);
}

static void vmk80xx_build_int_urb(struct urb *urb, int flag)
{
	struct vmk80xx_usb *dev = urb->context;
	__u8 rx_addr, tx_addr;
	unsigned int pipe;
	unsigned char *buf;
	size_t size;
	void (*callback) (struct urb *);
	int ival;

	dbgvm("vmk80xx: %s\n", __func__);

	if (flag & URB_RCV_FLAG) {
		rx_addr = dev->ep_rx->bEndpointAddress;
		pipe = usb_rcvintpipe(dev->udev, rx_addr);
		buf = dev->usb_rx_buf;
		size = le16_to_cpu(dev->ep_rx->wMaxPacketSize);
		callback = vmk80xx_rx_callback;
		ival = dev->ep_rx->bInterval;
	} else {		/* URB_SND_FLAG */
		tx_addr = dev->ep_tx->bEndpointAddress;
		pipe = usb_sndintpipe(dev->udev, tx_addr);
		buf = dev->usb_tx_buf;
		size = le16_to_cpu(dev->ep_tx->wMaxPacketSize);
		callback = vmk80xx_tx_callback;
		ival = dev->ep_tx->bInterval;
	}

	usb_fill_int_urb(urb, dev->udev, pipe, buf, size, callback, dev, ival);
}

static void vmk80xx_do_bulk_msg(struct vmk80xx_usb *dev)
{
	__u8 tx_addr, rx_addr;
	unsigned int tx_pipe, rx_pipe;
	size_t size;

	dbgvm("vmk80xx: %s\n", __func__);

	set_bit(TRANS_IN_BUSY, &dev->flags);
	set_bit(TRANS_OUT_BUSY, &dev->flags);

	tx_addr = dev->ep_tx->bEndpointAddress;
	rx_addr = dev->ep_rx->bEndpointAddress;
	tx_pipe = usb_sndbulkpipe(dev->udev, tx_addr);
	rx_pipe = usb_rcvbulkpipe(dev->udev, rx_addr);

	/* The max packet size attributes of the K8061
	 * input/output endpoints are identical */
	size = le16_to_cpu(dev->ep_tx->wMaxPacketSize);

	usb_bulk_msg(dev->udev, tx_pipe, dev->usb_tx_buf,
		     size, NULL, dev->ep_tx->bInterval);
	usb_bulk_msg(dev->udev, rx_pipe, dev->usb_rx_buf, size, NULL, HZ * 10);

	clear_bit(TRANS_OUT_BUSY, &dev->flags);
	clear_bit(TRANS_IN_BUSY, &dev->flags);
}

static int vmk80xx_read_packet(struct vmk80xx_usb *dev)
{
	struct urb *urb;
	int retval;

	dbgvm("vmk80xx: %s\n", __func__);

	if (!dev->intf)
		return -ENODEV;

	/* Only useful for interrupt transfers */
	if (test_bit(TRANS_IN_BUSY, &dev->flags))
		if (wait_event_interruptible(dev->read_wait,
					     !test_bit(TRANS_IN_BUSY,
						       &dev->flags)))
			return -ERESTART;

	if (dev->board.model == VMK8061_MODEL) {
		vmk80xx_do_bulk_msg(dev);

		return 0;
	}

	urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!urb)
		return -ENOMEM;

	urb->context = dev;
	vmk80xx_build_int_urb(urb, URB_RCV_FLAG);

	set_bit(TRANS_IN_RUNNING, &dev->flags);
	set_bit(TRANS_IN_BUSY, &dev->flags);

	usb_anchor_urb(urb, &dev->rx_anchor);

	retval = usb_submit_urb(urb, GFP_KERNEL);
	if (!retval)
		goto exit;

	clear_bit(TRANS_IN_RUNNING, &dev->flags);
	usb_unanchor_urb(urb);

exit:
	usb_free_urb(urb);

	return retval;
}

static int vmk80xx_write_packet(struct vmk80xx_usb *dev, int cmd)
{
	struct urb *urb;
	int retval;

	dbgvm("vmk80xx: %s\n", __func__);

	if (!dev->intf)
		return -ENODEV;

	if (test_bit(TRANS_OUT_BUSY, &dev->flags))
		if (wait_event_interruptible(dev->write_wait,
					     !test_bit(TRANS_OUT_BUSY,
						       &dev->flags)))
			return -ERESTART;

	if (dev->board.model == VMK8061_MODEL) {
		dev->usb_tx_buf[0] = cmd;
		vmk80xx_do_bulk_msg(dev);

		return 0;
	}

	urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!urb)
		return -ENOMEM;

	urb->context = dev;
	vmk80xx_build_int_urb(urb, URB_SND_FLAG);

	set_bit(TRANS_OUT_BUSY, &dev->flags);

	usb_anchor_urb(urb, &dev->tx_anchor);

	dev->usb_tx_buf[0] = cmd;

	retval = usb_submit_urb(urb, GFP_KERNEL);
	if (!retval)
		goto exit;

	clear_bit(TRANS_OUT_BUSY, &dev->flags);
	usb_unanchor_urb(urb);

exit:
	usb_free_urb(urb);

	return retval;
}

#define DIR_IN  1
#define DIR_OUT 2

#define rudimentary_check(dir)                             \
do {                                                       \
	if (!dev)                                          \
		return -EFAULT;                            \
	if (!dev->probed)                                  \
		return -ENODEV;                            \
	if (!dev->attached)                                \
		return -ENODEV;                            \
	if ((dir) & DIR_IN) {                              \
		if (test_bit(TRANS_IN_BUSY, &dev->flags))  \
			return -EBUSY;                     \
	} else {  /* DIR_OUT */                            \
		if (test_bit(TRANS_OUT_BUSY, &dev->flags)) \
			return -EBUSY;                     \
	}                                                  \
} while (0)

static int vmk80xx_ai_rinsn(struct comedi_device *cdev,
			    struct comedi_subdevice *s,
			    struct comedi_insn *insn, unsigned int *data)
{
	struct vmk80xx_usb *dev = cdev->private;
	int chan, reg[2];
	int n;

	dbgvm("vmk80xx: %s\n", __func__);

	rudimentary_check(DIR_IN);

	down(&dev->limit_sem);
	chan = CR_CHAN(insn->chanspec);

	switch (dev->board.model) {
	case VMK8055_MODEL:
		if (!chan)
			reg[0] = VMK8055_AI1_REG;
		else
			reg[0] = VMK8055_AI2_REG;
		break;
	case VMK8061_MODEL:
		reg[0] = VMK8061_AI_REG1;
		reg[1] = VMK8061_AI_REG2;
		dev->usb_tx_buf[0] = VMK8061_CMD_RD_AI;
		dev->usb_tx_buf[VMK8061_CH_REG] = chan;
		break;
	}

	for (n = 0; n < insn->n; n++) {
		if (vmk80xx_read_packet(dev))
			break;

		if (dev->board.model == VMK8055_MODEL) {
			data[n] = dev->usb_rx_buf[reg[0]];
			continue;
		}

		/* VMK8061_MODEL */
		data[n] = dev->usb_rx_buf[reg[0]] + 256 *
		    dev->usb_rx_buf[reg[1]];
	}

	up(&dev->limit_sem);

	return n;
}

static int vmk80xx_ao_winsn(struct comedi_device *cdev,
			    struct comedi_subdevice *s,
			    struct comedi_insn *insn, unsigned int *data)
{
	struct vmk80xx_usb *dev = cdev->private;
	int chan, cmd, reg;
	int n;

	dbgvm("vmk80xx: %s\n", __func__);

	rudimentary_check(DIR_OUT);

	down(&dev->limit_sem);
	chan = CR_CHAN(insn->chanspec);

	switch (dev->board.model) {
	case VMK8055_MODEL:
		cmd = VMK8055_CMD_WRT_AD;
		if (!chan)
			reg = VMK8055_AO1_REG;
		else
			reg = VMK8055_AO2_REG;
		break;
	default:		/* NOTE: avoid compiler warnings */
		cmd = VMK8061_CMD_SET_AO;
		reg = VMK8061_AO_REG;
		dev->usb_tx_buf[VMK8061_CH_REG] = chan;
		break;
	}

	for (n = 0; n < insn->n; n++) {
		dev->usb_tx_buf[reg] = data[n];

		if (vmk80xx_write_packet(dev, cmd))
			break;
	}

	up(&dev->limit_sem);

	return n;
}

static int vmk80xx_ao_rinsn(struct comedi_device *cdev,
			    struct comedi_subdevice *s,
			    struct comedi_insn *insn, unsigned int *data)
{
	struct vmk80xx_usb *dev = cdev->private;
	int chan, reg;
	int n;

	dbgvm("vmk80xx: %s\n", __func__);

	rudimentary_check(DIR_IN);

	down(&dev->limit_sem);
	chan = CR_CHAN(insn->chanspec);

	reg = VMK8061_AO_REG - 1;

	dev->usb_tx_buf[0] = VMK8061_CMD_RD_AO;

	for (n = 0; n < insn->n; n++) {
		if (vmk80xx_read_packet(dev))
			break;

		data[n] = dev->usb_rx_buf[reg + chan];
	}

	up(&dev->limit_sem);

	return n;
}

static int vmk80xx_di_rinsn(struct comedi_device *cdev,
			    struct comedi_subdevice *s,
			    struct comedi_insn *insn, unsigned int *data)
{
	struct vmk80xx_usb *dev = cdev->private;
	int chan;
	unsigned char *rx_buf;
	int reg, inp;
	int n;

	dbgvm("vmk80xx: %s\n", __func__);

	rudimentary_check(DIR_IN);

	down(&dev->limit_sem);
	chan = CR_CHAN(insn->chanspec);

	rx_buf = dev->usb_rx_buf;

	if (dev->board.model == VMK8061_MODEL) {
		reg = VMK8061_DI_REG;
		dev->usb_tx_buf[0] = VMK8061_CMD_RD_DI;
	} else
		reg = VMK8055_DI_REG;

	for (n = 0; n < insn->n; n++) {
		if (vmk80xx_read_packet(dev))
			break;

		if (dev->board.model == VMK8055_MODEL)
			inp = (((rx_buf[reg] >> 4) & 0x03) |
			       ((rx_buf[reg] << 2) & 0x04) |
			       ((rx_buf[reg] >> 3) & 0x18));
		else
			inp = rx_buf[reg];

		data[n] = ((inp & (1 << chan)) > 0);
	}

	up(&dev->limit_sem);

	return n;
}

static int vmk80xx_do_winsn(struct comedi_device *cdev,
			    struct comedi_subdevice *s,
			    struct comedi_insn *insn, unsigned int *data)
{

	struct vmk80xx_usb *dev = cdev->private;
	int chan;
	unsigned char *tx_buf;
	int reg, cmd;
	int n;

	dbgvm("vmk80xx: %s\n", __func__);

	rudimentary_check(DIR_OUT);

	down(&dev->limit_sem);
	chan = CR_CHAN(insn->chanspec);

	tx_buf = dev->usb_tx_buf;

	for (n = 0; n < insn->n; n++) {
		if (dev->board.model == VMK8055_MODEL) {
			reg = VMK8055_DO_REG;
			cmd = VMK8055_CMD_WRT_AD;
			if (data[n] == 1)
				tx_buf[reg] |= (1 << chan);
			else
				tx_buf[reg] ^= (1 << chan);

			goto write_packet;
		}

		/* VMK8061_MODEL */
		reg = VMK8061_DO_REG;
		if (data[n] == 1) {
			cmd = VMK8061_CMD_SET_DO;
			tx_buf[reg] = 1 << chan;
		} else {
			cmd = VMK8061_CMD_CLR_DO;
			tx_buf[reg] = 0xff - (1 << chan);
		}

write_packet:
		if (vmk80xx_write_packet(dev, cmd))
			break;
	}

	up(&dev->limit_sem);

	return n;
}

static int vmk80xx_do_rinsn(struct comedi_device *cdev,
			    struct comedi_subdevice *s,
			    struct comedi_insn *insn, unsigned int *data)
{
	struct vmk80xx_usb *dev = cdev->private;
	int chan, reg, mask;
	int n;

	dbgvm("vmk80xx: %s\n", __func__);

	rudimentary_check(DIR_IN);

	down(&dev->limit_sem);
	chan = CR_CHAN(insn->chanspec);

	reg = VMK8061_DO_REG;
	mask = 1 << chan;

	dev->usb_tx_buf[0] = VMK8061_CMD_RD_DO;

	for (n = 0; n < insn->n; n++) {
		if (vmk80xx_read_packet(dev))
			break;

		data[n] = (dev->usb_rx_buf[reg] & mask) >> chan;
	}

	up(&dev->limit_sem);

	return n;
}

static int vmk80xx_cnt_rinsn(struct comedi_device *cdev,
			     struct comedi_subdevice *s,
			     struct comedi_insn *insn, unsigned int *data)
{
	struct vmk80xx_usb *dev = cdev->private;
	int chan, reg[2];
	int n;

	dbgvm("vmk80xx: %s\n", __func__);

	rudimentary_check(DIR_IN);

	down(&dev->limit_sem);
	chan = CR_CHAN(insn->chanspec);

	switch (dev->board.model) {
	case VMK8055_MODEL:
		if (!chan)
			reg[0] = VMK8055_CNT1_REG;
		else
			reg[0] = VMK8055_CNT2_REG;
		break;
	case VMK8061_MODEL:
		reg[0] = VMK8061_CNT_REG;
		reg[1] = VMK8061_CNT_REG;
		dev->usb_tx_buf[0] = VMK8061_CMD_RD_CNT;
		break;
	}

	for (n = 0; n < insn->n; n++) {
		if (vmk80xx_read_packet(dev))
			break;

		if (dev->board.model == VMK8055_MODEL) {
			data[n] = dev->usb_rx_buf[reg[0]];
			continue;
		}

		/* VMK8061_MODEL */
		data[n] = dev->usb_rx_buf[reg[0] * (chan + 1) + 1]
		    + 256 * dev->usb_rx_buf[reg[1] * 2 + 2];
	}

	up(&dev->limit_sem);

	return n;
}

static int vmk80xx_cnt_cinsn(struct comedi_device *cdev,
			     struct comedi_subdevice *s,
			     struct comedi_insn *insn, unsigned int *data)
{
	struct vmk80xx_usb *dev = cdev->private;
	unsigned int insn_cmd;
	int chan, cmd, reg;
	int n;

	dbgvm("vmk80xx: %s\n", __func__);

	rudimentary_check(DIR_OUT);

	down(&dev->limit_sem);

	insn_cmd = data[0];
	if (insn_cmd != INSN_CONFIG_RESET && insn_cmd != GPCT_RESET)
		return -EINVAL;

	chan = CR_CHAN(insn->chanspec);

	if (dev->board.model == VMK8055_MODEL) {
		if (!chan) {
			cmd = VMK8055_CMD_RST_CNT1;
			reg = VMK8055_CNT1_REG;
		} else {
			cmd = VMK8055_CMD_RST_CNT2;
			reg = VMK8055_CNT2_REG;
		}

		dev->usb_tx_buf[reg] = 0x00;
	} else
		cmd = VMK8061_CMD_RST_CNT;

	for (n = 0; n < insn->n; n++)
		if (vmk80xx_write_packet(dev, cmd))
			break;

	up(&dev->limit_sem);

	return n;
}

static int vmk80xx_cnt_winsn(struct comedi_device *cdev,
			     struct comedi_subdevice *s,
			     struct comedi_insn *insn, unsigned int *data)
{
	struct vmk80xx_usb *dev = cdev->private;
	unsigned long debtime, val;
	int chan, cmd;
	int n;

	dbgvm("vmk80xx: %s\n", __func__);

	rudimentary_check(DIR_OUT);

	down(&dev->limit_sem);
	chan = CR_CHAN(insn->chanspec);

	if (!chan)
		cmd = VMK8055_CMD_DEB1_TIME;
	else
		cmd = VMK8055_CMD_DEB2_TIME;

	for (n = 0; n < insn->n; n++) {
		debtime = data[n];
		if (debtime == 0)
			debtime = 1;

		/* TODO: Prevent overflows */
		if (debtime > 7450)
			debtime = 7450;

		val = int_sqrt(debtime * 1000 / 115);
		if (((val + 1) * val) < debtime * 1000 / 115)
			val += 1;

		dev->usb_tx_buf[6 + chan] = val;

		if (vmk80xx_write_packet(dev, cmd))
			break;
	}

	up(&dev->limit_sem);

	return n;
}

static int vmk80xx_pwm_rinsn(struct comedi_device *cdev,
			     struct comedi_subdevice *s,
			     struct comedi_insn *insn, unsigned int *data)
{
	struct vmk80xx_usb *dev = cdev->private;
	int reg[2];
	int n;

	dbgvm("vmk80xx: %s\n", __func__);

	rudimentary_check(DIR_IN);

	down(&dev->limit_sem);

	reg[0] = VMK8061_PWM_REG1;
	reg[1] = VMK8061_PWM_REG2;

	dev->usb_tx_buf[0] = VMK8061_CMD_RD_PWM;

	for (n = 0; n < insn->n; n++) {
		if (vmk80xx_read_packet(dev))
			break;

		data[n] = dev->usb_rx_buf[reg[0]] + 4 * dev->usb_rx_buf[reg[1]];
	}

	up(&dev->limit_sem);

	return n;
}

static int vmk80xx_pwm_winsn(struct comedi_device *cdev,
			     struct comedi_subdevice *s,
			     struct comedi_insn *insn, unsigned int *data)
{
	struct vmk80xx_usb *dev = cdev->private;
	unsigned char *tx_buf;
	int reg[2], cmd;
	int n;

	dbgvm("vmk80xx: %s\n", __func__);

	rudimentary_check(DIR_OUT);

	down(&dev->limit_sem);

	tx_buf = dev->usb_tx_buf;

	reg[0] = VMK8061_PWM_REG1;
	reg[1] = VMK8061_PWM_REG2;

	cmd = VMK8061_CMD_OUT_PWM;

	/*
	 * The followin piece of code was translated from the inline
	 * assembler code in the DLL source code.
	 *
	 * asm
	 *   mov eax, k  ; k is the value (data[n])
	 *   and al, 03h ; al are the lower 8 bits of eax
	 *   mov lo, al  ; lo is the low part (tx_buf[reg[0]])
	 *   mov eax, k
	 *   shr eax, 2  ; right shift eax register by 2
	 *   mov hi, al  ; hi is the high part (tx_buf[reg[1]])
	 * end;
	 */
	for (n = 0; n < insn->n; n++) {
		tx_buf[reg[0]] = (unsigned char)(data[n] & 0x03);
		tx_buf[reg[1]] = (unsigned char)(data[n] >> 2) & 0xff;

		if (vmk80xx_write_packet(dev, cmd))
			break;
	}

	up(&dev->limit_sem);

	return n;
}

static int
vmk80xx_attach(struct comedi_device *cdev, struct comedi_devconfig *it)
{
	int i;
	struct vmk80xx_usb *dev;
	int n_subd;
	struct comedi_subdevice *s;
	int minor;

	dbgvm("vmk80xx: %s\n", __func__);

	mutex_lock(&glb_mutex);

	for (i = 0; i < VMK80XX_MAX_BOARDS; i++)
		if (vmb[i].probed && !vmb[i].attached)
			break;

	if (i == VMK80XX_MAX_BOARDS) {
		mutex_unlock(&glb_mutex);
		return -ENODEV;
	}

	dev = &vmb[i];

	down(&dev->limit_sem);

	cdev->board_name = dev->board.name;
	cdev->private = dev;

	if (dev->board.model == VMK8055_MODEL)
		n_subd = 5;
	else
		n_subd = 6;

	if (alloc_subdevices(cdev, n_subd) < 0) {
		up(&dev->limit_sem);
		mutex_unlock(&glb_mutex);
		return -ENOMEM;
	}

	/* Analog input subdevice */
	s = cdev->subdevices + VMK80XX_SUBD_AI;
	s->type = COMEDI_SUBD_AI;
	s->subdev_flags = SDF_READABLE | SDF_GROUND;
	s->n_chan = dev->board.ai_chans;
	s->maxdata = (1 << dev->board.ai_bits) - 1;
	s->range_table = dev->board.range;
	s->insn_read = vmk80xx_ai_rinsn;

	/* Analog output subdevice */
	s = cdev->subdevices + VMK80XX_SUBD_AO;
	s->type = COMEDI_SUBD_AO;
	s->subdev_flags = SDF_WRITEABLE | SDF_GROUND;
	s->n_chan = dev->board.ao_chans;
	s->maxdata = (1 << dev->board.ao_bits) - 1;
	s->range_table = dev->board.range;
	s->insn_write = vmk80xx_ao_winsn;

	if (dev->board.model == VMK8061_MODEL) {
		s->subdev_flags |= SDF_READABLE;
		s->insn_read = vmk80xx_ao_rinsn;
	}

	/* Digital input subdevice */
	s = cdev->subdevices + VMK80XX_SUBD_DI;
	s->type = COMEDI_SUBD_DI;
	s->subdev_flags = SDF_READABLE | SDF_GROUND;
	s->n_chan = dev->board.di_chans;
	s->maxdata = (1 << dev->board.di_bits) - 1;
	s->insn_read = vmk80xx_di_rinsn;

	/* Digital output subdevice */
	s = cdev->subdevices + VMK80XX_SUBD_DO;
	s->type = COMEDI_SUBD_DO;
	s->subdev_flags = SDF_WRITEABLE | SDF_GROUND;
	s->n_chan = dev->board.do_chans;
	s->maxdata = (1 << dev->board.do_bits) - 1;
	s->insn_write = vmk80xx_do_winsn;

	if (dev->board.model == VMK8061_MODEL) {
		s->subdev_flags |= SDF_READABLE;
		s->insn_read = vmk80xx_do_rinsn;
	}

	/* Counter subdevice */
	s = cdev->subdevices + VMK80XX_SUBD_CNT;
	s->type = COMEDI_SUBD_COUNTER;
	s->subdev_flags = SDF_READABLE;
	s->n_chan = dev->board.cnt_chans;
	s->insn_read = vmk80xx_cnt_rinsn;
	s->insn_config = vmk80xx_cnt_cinsn;

	if (dev->board.model == VMK8055_MODEL) {
		s->subdev_flags |= SDF_WRITEABLE;
		s->maxdata = (1 << dev->board.cnt_bits) - 1;
		s->insn_write = vmk80xx_cnt_winsn;
	}

	/* PWM subdevice */
	if (dev->board.model == VMK8061_MODEL) {
		s = cdev->subdevices + VMK80XX_SUBD_PWM;
		s->type = COMEDI_SUBD_PWM;
		s->subdev_flags = SDF_READABLE | SDF_WRITEABLE;
		s->n_chan = dev->board.pwm_chans;
		s->maxdata = (1 << dev->board.pwm_bits) - 1;
		s->insn_read = vmk80xx_pwm_rinsn;
		s->insn_write = vmk80xx_pwm_winsn;
	}

	dev->attached = 1;

	minor = cdev->minor;

	printk(KERN_INFO
	       "comedi%d: vmk80xx: board #%d [%s] attached to comedi\n",
	       minor, dev->count, dev->board.name);

	up(&dev->limit_sem);
	mutex_unlock(&glb_mutex);

	return 0;
}

static int vmk80xx_detach(struct comedi_device *cdev)
{
	struct vmk80xx_usb *dev;
	int minor;

	dbgvm("vmk80xx: %s\n", __func__);

	if (!cdev)
		return -EFAULT;

	dev = cdev->private;
	if (!dev)
		return -EFAULT;

	down(&dev->limit_sem);

	cdev->private = NULL;
	dev->attached = 0;

	minor = cdev->minor;

	printk(KERN_INFO
	       "comedi%d: vmk80xx: board #%d [%s] detached from comedi\n",
	       minor, dev->count, dev->board.name);

	up(&dev->limit_sem);

	return 0;
}

static int
vmk80xx_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
	int i;
	struct vmk80xx_usb *dev;
	struct usb_host_interface *iface_desc;
	struct usb_endpoint_descriptor *ep_desc;
	size_t size;

	dbgvm("vmk80xx: %s\n", __func__);

	mutex_lock(&glb_mutex);

	for (i = 0; i < VMK80XX_MAX_BOARDS; i++)
		if (!vmb[i].probed)
			break;

	if (i == VMK80XX_MAX_BOARDS) {
		mutex_unlock(&glb_mutex);
		return -EMFILE;
	}

	dev = &vmb[i];

	memset(dev, 0x00, sizeof(struct vmk80xx_usb));
	dev->count = i;

	iface_desc = intf->cur_altsetting;
	if (iface_desc->desc.bNumEndpoints != 2)
		goto error;

	for (i = 0; i < iface_desc->desc.bNumEndpoints; i++) {
		ep_desc = &iface_desc->endpoint[i].desc;

		if (usb_endpoint_is_int_in(ep_desc)) {
			dev->ep_rx = ep_desc;
			continue;
		}

		if (usb_endpoint_is_int_out(ep_desc)) {
			dev->ep_tx = ep_desc;
			continue;
		}

		if (usb_endpoint_is_bulk_in(ep_desc)) {
			dev->ep_rx = ep_desc;
			continue;
		}

		if (usb_endpoint_is_bulk_out(ep_desc)) {
			dev->ep_tx = ep_desc;
			continue;
		}
	}

	if (!dev->ep_rx || !dev->ep_tx)
		goto error;

	size = le16_to_cpu(dev->ep_rx->wMaxPacketSize);
	dev->usb_rx_buf = kmalloc(size, GFP_KERNEL);
	if (!dev->usb_rx_buf) {
		mutex_unlock(&glb_mutex);
		return -ENOMEM;
	}

	size = le16_to_cpu(dev->ep_tx->wMaxPacketSize);
	dev->usb_tx_buf = kmalloc(size, GFP_KERNEL);
	if (!dev->usb_tx_buf) {
		kfree(dev->usb_rx_buf);
		mutex_unlock(&glb_mutex);
		return -ENOMEM;
	}

	dev->udev = interface_to_usbdev(intf);
	dev->intf = intf;

	sema_init(&dev->limit_sem, 8);
	init_waitqueue_head(&dev->read_wait);
	init_waitqueue_head(&dev->write_wait);

	init_usb_anchor(&dev->rx_anchor);
	init_usb_anchor(&dev->tx_anchor);

	usb_set_intfdata(intf, dev);

	switch (id->driver_info) {
	case DEVICE_VMK8055:
		dev->board.name = "K8055 (VM110)";
		dev->board.model = VMK8055_MODEL;
		dev->board.range = &vmk8055_range;
		dev->board.ai_chans = 2;
		dev->board.ai_bits = 8;
		dev->board.ao_chans = 2;
		dev->board.ao_bits = 8;
		dev->board.di_chans = 5;
		dev->board.di_bits = 1;
		dev->board.do_chans = 8;
		dev->board.do_bits = 1;
		dev->board.cnt_chans = 2;
		dev->board.cnt_bits = 16;
		dev->board.pwm_chans = 0;
		dev->board.pwm_bits = 0;
		break;
	case DEVICE_VMK8061:
		dev->board.name = "K8061 (VM140)";
		dev->board.model = VMK8061_MODEL;
		dev->board.range = &vmk8061_range;
		dev->board.ai_chans = 8;
		dev->board.ai_bits = 10;
		dev->board.ao_chans = 8;
		dev->board.ao_bits = 8;
		dev->board.di_chans = 8;
		dev->board.di_bits = 1;
		dev->board.do_chans = 8;
		dev->board.do_bits = 1;
		dev->board.cnt_chans = 2;
		dev->board.cnt_bits = 0;
		dev->board.pwm_chans = 1;
		dev->board.pwm_bits = 10;
		break;
	}

	if (dev->board.model == VMK8061_MODEL) {
		vmk80xx_read_eeprom(dev, IC3_VERSION);
		printk(KERN_INFO "comedi#: vmk80xx: %s\n", dev->fw.ic3_vers);

		if (vmk80xx_check_data_link(dev)) {
			vmk80xx_read_eeprom(dev, IC6_VERSION);
			printk(KERN_INFO "comedi#: vmk80xx: %s\n",
			       dev->fw.ic6_vers);
		} else
			dbgcm("comedi#: vmk80xx: no conn. to CPU\n");
	}

	if (dev->board.model == VMK8055_MODEL)
		vmk80xx_reset_device(dev);

	dev->probed = 1;

	printk(KERN_INFO "comedi#: vmk80xx: board #%d [%s] now attached\n",
	       dev->count, dev->board.name);

	mutex_unlock(&glb_mutex);

	return 0;
error:
	mutex_unlock(&glb_mutex);

	return -ENODEV;
}

static void vmk80xx_disconnect(struct usb_interface *intf)
{
	struct vmk80xx_usb *dev = usb_get_intfdata(intf);

	dbgvm("vmk80xx: %s\n", __func__);

	if (!dev)
		return;

	mutex_lock(&glb_mutex);
	down(&dev->limit_sem);

	dev->probed = 0;
	usb_set_intfdata(dev->intf, NULL);

	usb_kill_anchored_urbs(&dev->rx_anchor);
	usb_kill_anchored_urbs(&dev->tx_anchor);

	kfree(dev->usb_rx_buf);
	kfree(dev->usb_tx_buf);

	printk(KERN_INFO "comedi#: vmk80xx: board #%d [%s] now detached\n",
	       dev->count, dev->board.name);

	up(&dev->limit_sem);
	mutex_unlock(&glb_mutex);
}

/* TODO: Add support for suspend, resume, pre_reset,
 * post_reset and flush */
static struct usb_driver vmk80xx_driver = {
	.name = "vmk80xx",
	.probe = vmk80xx_probe,
	.disconnect = vmk80xx_disconnect,
	.id_table = vmk80xx_id_table
};

static struct comedi_driver driver_vmk80xx = {
	.module = THIS_MODULE,
	.driver_name = "vmk80xx",
	.attach = vmk80xx_attach,
	.detach = vmk80xx_detach
};

static int __init vmk80xx_init(void)
{
	printk(KERN_INFO "vmk80xx: version 0.8.01 "
	       "Manuel Gebele <forensixs@gmx.de>\n");
	usb_register(&vmk80xx_driver);
	return comedi_driver_register(&driver_vmk80xx);
}

static void __exit vmk80xx_exit(void)
{
	comedi_driver_unregister(&driver_vmk80xx);
	usb_deregister(&vmk80xx_driver);
}

module_init(vmk80xx_init);
module_exit(vmk80xx_exit);