/*
   comedi/drivers/pcl816.c

   Author:  Juan Grigera <juan@grigera.com.ar>
	    based on pcl818 by Michal Dobes <dobes@tesnet.cz> and bits of pcl812

   hardware driver for Advantech cards:
    card:   PCL-816, PCL814B
    driver: pcl816
*/
/*
Driver: pcl816
Description: Advantech PCL-816 cards, PCL-814
Author: Juan Grigera <juan@grigera.com.ar>
Devices: [Advantech] PCL-816 (pcl816), PCL-814B (pcl814b)
Status: works
Updated: Tue,  2 Apr 2002 23:15:21 -0800

PCL 816 and 814B have 16 SE/DIFF ADCs, 16 DACs, 16 DI and 16 DO.
Differences are at resolution (16 vs 12 bits).

The driver support AI command mode, other subdevices not written.

Analog output and digital input and output are not supported.

Configuration Options:
  [0] - IO Base
  [1] - IRQ	(0=disable, 2, 3, 4, 5, 6, 7)
  [2] - DMA	(0=disable, 1, 3)
  [3] - 0, 10=10MHz clock for 8254
	    1= 1MHz clock for 8254

*/

#include <linux/module.h>
#include "../comedidev.h"

#include <linux/gfp.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/interrupt.h>
#include <asm/dma.h>

#include "comedi_fc.h"
#include "8253.h"

/*
 * Register I/O map
 */
#define PCL816_DO_DI_LSB_REG			0x00
#define PCL816_DO_DI_MSB_REG			0x01
#define PCL816_TIMER_BASE			0x04
#define PCL816_AI_LSB_REG			0x08
#define PCL816_AI_MSB_REG			0x09
#define PCL816_RANGE_REG			0x09
#define PCL816_CLRINT_REG			0x0a
#define PCL816_MUX_REG				0x0b
#define PCL816_MUX_SCAN(_first, _last)		(((_last) << 4) | (_first))
#define PCL816_CTRL_REG				0x0c
#define PCL816_CTRL_DISABLE_TRIG		(0 << 0)
#define PCL816_CTRL_SOFT_TRIG			(1 << 0)
#define PCL816_CTRL_PACER_TRIG			(1 << 1)
#define PCL816_CTRL_EXT_TRIG			(1 << 2)
#define PCL816_CTRL_POE				(1 << 3)
#define PCL816_CTRL_DMAEN			(1 << 4)
#define PCL816_CTRL_INTEN			(1 << 5)
#define PCL816_CTRL_DMASRC_SLOT0		(0 << 6)
#define PCL816_CTRL_DMASRC_SLOT1		(1 << 6)
#define PCL816_CTRL_DMASRC_SLOT2		(2 << 6)
#define PCL816_STATUS_REG			0x0d
#define PCL816_STATUS_NEXT_CHAN_MASK		(0xf << 0)
#define PCL816_STATUS_INTSRC_MASK		(3 << 4)
#define PCL816_STATUS_INTSRC_SLOT0		(0 << 4)
#define PCL816_STATUS_INTSRC_SLOT1		(1 << 4)
#define PCL816_STATUS_INTSRC_SLOT2		(2 << 4)
#define PCL816_STATUS_INTSRC_DMA		(3 << 4)
#define PCL816_STATUS_INTACT			(1 << 6)
#define PCL816_STATUS_DRDY			(1 << 7)

#define MAGIC_DMA_WORD 0x5a5a

static const struct comedi_lrange range_pcl816 = {
	8, {
		BIP_RANGE(10),
		BIP_RANGE(5),
		BIP_RANGE(2.5),
		BIP_RANGE(1.25),
		UNI_RANGE(10),
		UNI_RANGE(5),
		UNI_RANGE(2.5),
		UNI_RANGE(1.25)
	}
};

struct pcl816_board {
	const char *name;
	int ai_maxdata;
	int ao_maxdata;
	int ai_chanlist;
};

static const struct pcl816_board boardtypes[] = {
	{
		.name		= "pcl816",
		.ai_maxdata	= 0xffff,
		.ao_maxdata	= 0xffff,
		.ai_chanlist	= 1024,
	}, {
		.name		= "pcl814b",
		.ai_maxdata	= 0x3fff,
		.ao_maxdata	= 0x3fff,
		.ai_chanlist	= 1024,
	},
};

struct pcl816_private {
	unsigned int dma;	/*  used DMA, 0=don't use DMA */
	unsigned int dmapages;
	unsigned int hwdmasize;
	unsigned long dmabuf[2];	/*  pointers to begin of DMA buffers */
	unsigned int hwdmaptr[2];	/*  hardware address of DMA buffers */
	int next_dma_buf;	/*  which DMA buffer will be used next round */
	long dma_runs_to_end;	/*  how many we must permorm DMA transfer to end of record */
	unsigned long last_dma_run;	/*  how many bytes we must transfer on last DMA page */
	int ai_act_scan;	/*  how many scans we finished */
	unsigned int ai_poll_ptr;	/*  how many sampes transfer poll */
	unsigned int divisor1;
	unsigned int divisor2;
	unsigned int ai_cmd_running:1;
	unsigned int ai_cmd_canceled:1;
};

static void pcl816_start_pacer(struct comedi_device *dev, bool load_counters)
{
	struct pcl816_private *devpriv = dev->private;
	unsigned long timer_base = dev->iobase + PCL816_TIMER_BASE;

	i8254_set_mode(timer_base, 0, 0, I8254_MODE1 | I8254_BINARY);
	i8254_write(timer_base, 0, 0, 0x00ff);
	udelay(1);

	i8254_set_mode(timer_base, 0, 2, I8254_MODE2 | I8254_BINARY);
	i8254_set_mode(timer_base, 0, 1, I8254_MODE2 | I8254_BINARY);
	udelay(1);

	if (load_counters) {
		i8254_write(timer_base, 0, 2, devpriv->divisor2);
		i8254_write(timer_base, 0, 1, devpriv->divisor1);
	}
}

static void pcl816_ai_setup_dma(struct comedi_device *dev,
				struct comedi_subdevice *s)
{
	struct pcl816_private *devpriv = dev->private;
	struct comedi_cmd *cmd = &s->async->cmd;
	unsigned int dma_flags;
	unsigned int bytes;

	bytes = devpriv->hwdmasize;
	if (cmd->stop_src == TRIG_COUNT) {
		/*  how many */
		bytes = cmd->stop_arg * cfc_bytes_per_scan(s);

		/*  how many DMA pages we must fill */
		devpriv->dma_runs_to_end = bytes / devpriv->hwdmasize;

		/* on last dma transfer must be moved */
		devpriv->last_dma_run = bytes % devpriv->hwdmasize;
		devpriv->dma_runs_to_end--;
		if (devpriv->dma_runs_to_end >= 0)
			bytes = devpriv->hwdmasize;
	} else
		devpriv->dma_runs_to_end = -1;

	devpriv->next_dma_buf = 0;
	set_dma_mode(devpriv->dma, DMA_MODE_READ);
	dma_flags = claim_dma_lock();
	clear_dma_ff(devpriv->dma);
	set_dma_addr(devpriv->dma, devpriv->hwdmaptr[0]);
	set_dma_count(devpriv->dma, bytes);
	release_dma_lock(dma_flags);
	enable_dma(devpriv->dma);
}

static void pcl816_ai_setup_next_dma(struct comedi_device *dev,
				     struct comedi_subdevice *s)
{
	struct pcl816_private *devpriv = dev->private;
	struct comedi_cmd *cmd = &s->async->cmd;
	unsigned long dma_flags;

	disable_dma(devpriv->dma);
	if (devpriv->dma_runs_to_end > -1 || cmd->stop_src == TRIG_NONE) {
		/* switch dma bufs */
		devpriv->next_dma_buf = 1 - devpriv->next_dma_buf;
		set_dma_mode(devpriv->dma, DMA_MODE_READ);
		dma_flags = claim_dma_lock();
		set_dma_addr(devpriv->dma,
			     devpriv->hwdmaptr[devpriv->next_dma_buf]);
		if (devpriv->dma_runs_to_end)
			set_dma_count(devpriv->dma, devpriv->hwdmasize);
		else
			set_dma_count(devpriv->dma, devpriv->last_dma_run);
		release_dma_lock(dma_flags);
		enable_dma(devpriv->dma);
	}

	devpriv->dma_runs_to_end--;
}

static void pcl816_ai_set_chan_range(struct comedi_device *dev,
				     unsigned int chan,
				     unsigned int range)
{
	outb(chan, dev->iobase + PCL816_MUX_REG);
	outb(range, dev->iobase + PCL816_RANGE_REG);
}

static void pcl816_ai_set_chan_scan(struct comedi_device *dev,
				    unsigned int first_chan,
				    unsigned int last_chan)
{
	outb(PCL816_MUX_SCAN(first_chan, last_chan),
	     dev->iobase + PCL816_MUX_REG);
}

static void pcl816_ai_setup_chanlist(struct comedi_device *dev,
				     unsigned int *chanlist,
				     unsigned int seglen)
{
	unsigned int first_chan = CR_CHAN(chanlist[0]);
	unsigned int last_chan;
	unsigned int range;
	unsigned int i;

	/* store range list to card */
	for (i = 0; i < seglen; i++) {
		last_chan = CR_CHAN(chanlist[i]);
		range = CR_RANGE(chanlist[i]);

		pcl816_ai_set_chan_range(dev, last_chan, range);
	}

	udelay(1);

	pcl816_ai_set_chan_scan(dev, first_chan, last_chan);
}

static void pcl816_ai_clear_eoc(struct comedi_device *dev)
{
	/* writing any value clears the interrupt request */
	outb(0, dev->iobase + PCL816_CLRINT_REG);
}

static void pcl816_ai_soft_trig(struct comedi_device *dev)
{
	/* writing any value triggers a software conversion */
	outb(0, dev->iobase + PCL816_AI_LSB_REG);
}

static unsigned int pcl816_ai_get_sample(struct comedi_device *dev,
					 struct comedi_subdevice *s)
{
	unsigned int val;

	val = inb(dev->iobase + PCL816_AI_MSB_REG) << 8;
	val |= inb(dev->iobase + PCL816_AI_LSB_REG);

	return val & s->maxdata;
}

static int pcl816_ai_eoc(struct comedi_device *dev,
			 struct comedi_subdevice *s,
			 struct comedi_insn *insn,
			 unsigned long context)
{
	unsigned int status;

	status = inb(dev->iobase + PCL816_STATUS_REG);
	if ((status & PCL816_STATUS_DRDY) == 0)
		return 0;
	return -EBUSY;
}

static bool pcl816_ai_next_chan(struct comedi_device *dev,
				struct comedi_subdevice *s)
{
	struct pcl816_private *devpriv = dev->private;
	struct comedi_cmd *cmd = &s->async->cmd;

	s->async->events |= COMEDI_CB_BLOCK;

	s->async->cur_chan++;
	if (s->async->cur_chan >= cmd->chanlist_len) {
		s->async->cur_chan = 0;
		devpriv->ai_act_scan++;
		s->async->events |= COMEDI_CB_EOS;
	}

	if (cmd->stop_src == TRIG_COUNT &&
	    devpriv->ai_act_scan >= cmd->stop_arg) {
		/* all data sampled */
		s->async->events |= COMEDI_CB_EOA;
		return false;
	}

	return true;
}

static void transfer_from_dma_buf(struct comedi_device *dev,
				  struct comedi_subdevice *s,
				  unsigned short *ptr,
				  unsigned int bufptr, unsigned int len)
{
	int i;

	for (i = 0; i < len; i++) {
		comedi_buf_put(s, ptr[bufptr++]);

		if (!pcl816_ai_next_chan(dev, s))
			return;
	}
}

static irqreturn_t pcl816_interrupt(int irq, void *d)
{
	struct comedi_device *dev = d;
	struct comedi_subdevice *s = dev->read_subdev;
	struct pcl816_private *devpriv = dev->private;
	unsigned short *ptr;
	unsigned int bufptr;
	unsigned int len;

	if (!dev->attached || !devpriv->ai_cmd_running) {
		pcl816_ai_clear_eoc(dev);
		return IRQ_HANDLED;
	}

	if (devpriv->ai_cmd_canceled) {
		devpriv->ai_cmd_canceled = 0;
		pcl816_ai_clear_eoc(dev);
		return IRQ_HANDLED;
	}

	ptr = (unsigned short *)devpriv->dmabuf[devpriv->next_dma_buf];

	pcl816_ai_setup_next_dma(dev, s);

	len = (devpriv->hwdmasize >> 1) - devpriv->ai_poll_ptr;
	bufptr = devpriv->ai_poll_ptr;
	devpriv->ai_poll_ptr = 0;

	transfer_from_dma_buf(dev, s, ptr, bufptr, len);

	pcl816_ai_clear_eoc(dev);

	cfc_handle_events(dev, s);
	return IRQ_HANDLED;
}

static int check_channel_list(struct comedi_device *dev,
			      struct comedi_subdevice *s,
			      unsigned int *chanlist,
			      unsigned int chanlen)
{
	unsigned int chansegment[16];
	unsigned int i, nowmustbechan, seglen, segpos;

	/*  correct channel and range number check itself comedi/range.c */
	if (chanlen < 1) {
		dev_err(dev->class_dev, "range/channel list is empty!\n");
		return 0;
	}

	if (chanlen > 1) {
		/*  first channel is every time ok */
		chansegment[0] = chanlist[0];
		for (i = 1, seglen = 1; i < chanlen; i++, seglen++) {
			/*  we detect loop, this must by finish */
			    if (chanlist[0] == chanlist[i])
				break;
			nowmustbechan =
			    (CR_CHAN(chansegment[i - 1]) + 1) % chanlen;
			if (nowmustbechan != CR_CHAN(chanlist[i])) {
				/*  channel list isn't continuous :-( */
				dev_dbg(dev->class_dev,
					"channel list must be continuous! chanlist[%i]=%d but must be %d or %d!\n",
					i, CR_CHAN(chanlist[i]), nowmustbechan,
					CR_CHAN(chanlist[0]));
				return 0;
			}
			/*  well, this is next correct channel in list */
			chansegment[i] = chanlist[i];
		}

		/*  check whole chanlist */
		for (i = 0, segpos = 0; i < chanlen; i++) {
			    if (chanlist[i] != chansegment[i % seglen]) {
				dev_dbg(dev->class_dev,
					"bad channel or range number! chanlist[%i]=%d,%d,%d and not %d,%d,%d!\n",
					i, CR_CHAN(chansegment[i]),
					CR_RANGE(chansegment[i]),
					CR_AREF(chansegment[i]),
					CR_CHAN(chanlist[i % seglen]),
					CR_RANGE(chanlist[i % seglen]),
					CR_AREF(chansegment[i % seglen]));
				return 0;	/*  chan/gain list is strange */
			}
		}
	} else {
		seglen = 1;
	}

	return seglen;	/*  we can serve this with MUX logic */
}

static int pcl816_ai_cmdtest(struct comedi_device *dev,
			     struct comedi_subdevice *s, struct comedi_cmd *cmd)
{
	struct pcl816_private *devpriv = dev->private;
	int err = 0;
	unsigned int arg;

	/* Step 1 : check if triggers are trivially valid */

	err |= cfc_check_trigger_src(&cmd->start_src, TRIG_NOW);
	err |= cfc_check_trigger_src(&cmd->scan_begin_src, TRIG_FOLLOW);
	err |= cfc_check_trigger_src(&cmd->convert_src, TRIG_EXT | TRIG_TIMER);
	err |= cfc_check_trigger_src(&cmd->scan_end_src, TRIG_COUNT);
	err |= cfc_check_trigger_src(&cmd->stop_src, TRIG_COUNT | TRIG_NONE);

	if (err)
		return 1;

	/* Step 2a : make sure trigger sources are unique */

	err |= cfc_check_trigger_is_unique(cmd->convert_src);
	err |= cfc_check_trigger_is_unique(cmd->stop_src);

	/* Step 2b : and mutually compatible */

	if (err)
		return 2;


	/* Step 3: check if arguments are trivially valid */

	err |= cfc_check_trigger_arg_is(&cmd->start_arg, 0);
	err |= cfc_check_trigger_arg_is(&cmd->scan_begin_arg, 0);

	if (cmd->convert_src == TRIG_TIMER)
		err |= cfc_check_trigger_arg_min(&cmd->convert_arg, 10000);
	else	/* TRIG_EXT */
		err |= cfc_check_trigger_arg_is(&cmd->convert_arg, 0);

	err |= cfc_check_trigger_arg_is(&cmd->scan_end_arg, cmd->chanlist_len);

	if (cmd->stop_src == TRIG_COUNT)
		err |= cfc_check_trigger_arg_min(&cmd->stop_arg, 1);
	else	/* TRIG_NONE */
		err |= cfc_check_trigger_arg_is(&cmd->stop_arg, 0);

	if (err)
		return 3;


	/* step 4: fix up any arguments */
	if (cmd->convert_src == TRIG_TIMER) {
		arg = cmd->convert_arg;
		i8253_cascade_ns_to_timer(I8254_OSC_BASE_10MHZ,
					  &devpriv->divisor1,
					  &devpriv->divisor2,
					  &arg, cmd->flags);
		err |= cfc_check_trigger_arg_is(&cmd->convert_arg, arg);
	}

	if (err)
		return 4;


	/* step 5: complain about special chanlist considerations */

	if (cmd->chanlist) {
		if (!check_channel_list(dev, s, cmd->chanlist,
					cmd->chanlist_len))
			return 5;	/*  incorrect channels list */
	}

	return 0;
}

static int pcl816_ai_cmd(struct comedi_device *dev, struct comedi_subdevice *s)
{
	struct pcl816_private *devpriv = dev->private;
	struct comedi_cmd *cmd = &s->async->cmd;
	unsigned int ctrl;
	unsigned int seglen;

	if (devpriv->ai_cmd_running)
		return -EBUSY;

	pcl816_start_pacer(dev, false);

	seglen = check_channel_list(dev, s, cmd->chanlist, cmd->chanlist_len);
	if (seglen < 1)
		return -EINVAL;
	pcl816_ai_setup_chanlist(dev, cmd->chanlist, seglen);
	udelay(1);

	devpriv->ai_act_scan = 0;
	s->async->cur_chan = 0;
	devpriv->ai_cmd_running = 1;
	devpriv->ai_poll_ptr = 0;
	devpriv->ai_cmd_canceled = 0;

	pcl816_ai_setup_dma(dev, s);

	pcl816_start_pacer(dev, true);

	ctrl = PCL816_CTRL_INTEN | PCL816_CTRL_DMAEN | PCL816_CTRL_DMASRC_SLOT0;
	if (cmd->convert_src == TRIG_TIMER)
		ctrl |= PCL816_CTRL_PACER_TRIG;
	else	/* TRIG_EXT */
		ctrl |= PCL816_CTRL_EXT_TRIG;

	outb(ctrl, dev->iobase + PCL816_CTRL_REG);
	outb((devpriv->dma << 4) | dev->irq, dev->iobase + PCL816_STATUS_REG);

	return 0;
}

static int pcl816_ai_poll(struct comedi_device *dev, struct comedi_subdevice *s)
{
	struct pcl816_private *devpriv = dev->private;
	unsigned long flags;
	unsigned int top1, top2, i;

	spin_lock_irqsave(&dev->spinlock, flags);

	for (i = 0; i < 20; i++) {
		top1 = get_dma_residue(devpriv->dma);	/*  where is now DMA */
		top2 = get_dma_residue(devpriv->dma);
		if (top1 == top2)
			break;
	}
	if (top1 != top2) {
		spin_unlock_irqrestore(&dev->spinlock, flags);
		return 0;
	}

	/*  where is now DMA in buffer */
	top1 = devpriv->hwdmasize - top1;
	top1 >>= 1;		/*  sample position */
	top2 = top1 - devpriv->ai_poll_ptr;
	if (top2 < 1) {		/*  no new samples */
		spin_unlock_irqrestore(&dev->spinlock, flags);
		return 0;
	}

	transfer_from_dma_buf(dev, s,
			      (unsigned short *)devpriv->dmabuf[devpriv->
								next_dma_buf],
			      devpriv->ai_poll_ptr, top2);

	devpriv->ai_poll_ptr = top1;	/*  new buffer position */
	spin_unlock_irqrestore(&dev->spinlock, flags);

	cfc_handle_events(dev, s);

	return comedi_buf_n_bytes_ready(s);
}

static int pcl816_ai_cancel(struct comedi_device *dev,
			    struct comedi_subdevice *s)
{
	struct pcl816_private *devpriv = dev->private;

	if (!devpriv->ai_cmd_running)
		return 0;

	outb(PCL816_CTRL_DISABLE_TRIG, dev->iobase + PCL816_CTRL_REG);
	pcl816_ai_clear_eoc(dev);

	/* Stop pacer */
	i8254_set_mode(dev->iobase + PCL816_TIMER_BASE, 0,
			2, I8254_MODE0 | I8254_BINARY);
	i8254_set_mode(dev->iobase + PCL816_TIMER_BASE, 0,
			1, I8254_MODE0 | I8254_BINARY);

	devpriv->ai_cmd_running = 0;
	devpriv->ai_cmd_canceled = 1;

	return 0;
}

static int pcl816_ai_insn_read(struct comedi_device *dev,
			       struct comedi_subdevice *s,
			       struct comedi_insn *insn,
			       unsigned int *data)
{
	unsigned int chan = CR_CHAN(insn->chanspec);
	unsigned int range = CR_RANGE(insn->chanspec);
	int ret = 0;
	int i;

	outb(PCL816_CTRL_SOFT_TRIG, dev->iobase + PCL816_CTRL_REG);

	pcl816_ai_set_chan_range(dev, chan, range);
	pcl816_ai_set_chan_scan(dev, chan, chan);

	for (i = 0; i < insn->n; i++) {
		pcl816_ai_clear_eoc(dev);
		pcl816_ai_soft_trig(dev);

		ret = comedi_timeout(dev, s, insn, pcl816_ai_eoc, 0);
		if (ret)
			break;

		data[i] = pcl816_ai_get_sample(dev, s);
	}
	outb(PCL816_CTRL_DISABLE_TRIG, dev->iobase + PCL816_CTRL_REG);
	pcl816_ai_clear_eoc(dev);

	return ret ? ret : insn->n;
}

static int pcl816_di_insn_bits(struct comedi_device *dev,
			       struct comedi_subdevice *s,
			       struct comedi_insn *insn,
			       unsigned int *data)
{
	data[1] = inb(dev->iobase + PCL816_DO_DI_LSB_REG) |
		  (inb(dev->iobase + PCL816_DO_DI_MSB_REG) << 8);

	return insn->n;
}

static int pcl816_do_insn_bits(struct comedi_device *dev,
			       struct comedi_subdevice *s,
			       struct comedi_insn *insn,
			       unsigned int *data)
{
	if (comedi_dio_update_state(s, data)) {
		outb(s->state & 0xff, dev->iobase + PCL816_DO_DI_LSB_REG);
		outb((s->state >> 8), dev->iobase + PCL816_DO_DI_MSB_REG);
	}

	data[1] = s->state;

	return insn->n;
}

static void pcl816_reset(struct comedi_device *dev)
{
	unsigned long timer_base = dev->iobase + PCL816_TIMER_BASE;

	outb(PCL816_CTRL_DISABLE_TRIG, dev->iobase + PCL816_CTRL_REG);
	pcl816_ai_set_chan_range(dev, 0, 0);
	pcl816_ai_clear_eoc(dev);

	/* Stop pacer */
	i8254_set_mode(timer_base, 0, 2, I8254_MODE0 | I8254_BINARY);
	i8254_set_mode(timer_base, 0, 1, I8254_MODE0 | I8254_BINARY);
	i8254_set_mode(timer_base, 0, 0, I8254_MODE0 | I8254_BINARY);

	/* set all digital outputs low */
	outb(0, dev->iobase + PCL816_DO_DI_LSB_REG);
	outb(0, dev->iobase + PCL816_DO_DI_MSB_REG);
}

static int pcl816_attach(struct comedi_device *dev, struct comedi_devconfig *it)
{
	const struct pcl816_board *board = dev->board_ptr;
	struct pcl816_private *devpriv;
	struct comedi_subdevice *s;
	int ret;
	int i;

	devpriv = comedi_alloc_devpriv(dev, sizeof(*devpriv));
	if (!devpriv)
		return -ENOMEM;

	ret = comedi_request_region(dev, it->options[0], 0x10);
	if (ret)
		return ret;

	/* we can use IRQ 2-7 for async command support */
	if (it->options[1] >= 2 && it->options[1] <= 7) {
		ret = request_irq(it->options[1], pcl816_interrupt, 0,
				  dev->board_name, dev);
		if (ret == 0)
			dev->irq = it->options[1];
	}

	/* we need an IRQ to do DMA on channel 3 or 1 */
	if (dev->irq && (it->options[2] == 3 || it->options[2] == 1)) {
		ret = request_dma(it->options[2], dev->board_name);
		if (ret) {
			dev_err(dev->class_dev,
				"unable to request DMA channel %d\n",
				it->options[2]);
			return -EBUSY;
		}
		devpriv->dma = it->options[2];

		devpriv->dmapages = 2;	/* we need 16KB */
		devpriv->hwdmasize = (1 << devpriv->dmapages) * PAGE_SIZE;

		for (i = 0; i < 2; i++) {
			unsigned long dmabuf;

			dmabuf = __get_dma_pages(GFP_KERNEL, devpriv->dmapages);
			if (!dmabuf)
				return -ENOMEM;

			devpriv->dmabuf[i] = dmabuf;
			devpriv->hwdmaptr[i] = virt_to_bus((void *)dmabuf);
		}
	}

	ret = comedi_alloc_subdevices(dev, 4);
	if (ret)
		return ret;

	s = &dev->subdevices[0];
	s->type		= COMEDI_SUBD_AI;
	s->subdev_flags	= SDF_CMD_READ | SDF_DIFF;
	s->n_chan	= 16;
	s->maxdata	= board->ai_maxdata;
	s->range_table	= &range_pcl816;
	s->insn_read	= pcl816_ai_insn_read;
	if (devpriv->dma) {
		dev->read_subdev = s;
		s->subdev_flags	|= SDF_CMD_READ;
		s->len_chanlist	= board->ai_chanlist;
		s->do_cmdtest	= pcl816_ai_cmdtest;
		s->do_cmd	= pcl816_ai_cmd;
		s->poll		= pcl816_ai_poll;
		s->cancel	= pcl816_ai_cancel;
	}

	/* Analog OUtput subdevice */
	s = &dev->subdevices[2];
	s->type		= COMEDI_SUBD_UNUSED;
#if 0
	subdevs[1] = COMEDI_SUBD_AO;
	s->subdev_flags = SDF_WRITABLE | SDF_GROUND;
	s->n_chan = 1;
	s->maxdata = board->ao_maxdata;
	s->range_table = &range_pcl816;
#endif

	/* Digital Input subdevice */
	s = &dev->subdevices[2];
	s->type		= COMEDI_SUBD_DI;
	s->subdev_flags	= SDF_READABLE;
	s->n_chan	= 16;
	s->maxdata	= 1;
	s->range_table	= &range_digital;
	s->insn_bits	= pcl816_di_insn_bits;

	/* Digital Output subdevice */
	s = &dev->subdevices[3];
	s->type		= COMEDI_SUBD_DO;
	s->subdev_flags	= SDF_WRITABLE;
	s->n_chan	= 16;
	s->maxdata	= 1;
	s->range_table	= &range_digital;
	s->insn_bits	= pcl816_do_insn_bits;

	pcl816_reset(dev);

	return 0;
}

static void pcl816_detach(struct comedi_device *dev)
{
	struct pcl816_private *devpriv = dev->private;

	if (dev->private) {
		pcl816_ai_cancel(dev, dev->read_subdev);
		pcl816_reset(dev);
		if (devpriv->dma)
			free_dma(devpriv->dma);
		if (devpriv->dmabuf[0])
			free_pages(devpriv->dmabuf[0], devpriv->dmapages);
		if (devpriv->dmabuf[1])
			free_pages(devpriv->dmabuf[1], devpriv->dmapages);
	}
	comedi_legacy_detach(dev);
}

static struct comedi_driver pcl816_driver = {
	.driver_name	= "pcl816",
	.module		= THIS_MODULE,
	.attach		= pcl816_attach,
	.detach		= pcl816_detach,
	.board_name	= &boardtypes[0].name,
	.num_names	= ARRAY_SIZE(boardtypes),
	.offset		= sizeof(struct pcl816_board),
};
module_comedi_driver(pcl816_driver);

MODULE_AUTHOR("Comedi http://www.comedi.org");
MODULE_DESCRIPTION("Comedi low-level driver");
MODULE_LICENSE("GPL");
